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Note: This is a preliminary program as of March 28, 1997. Papers on the technical program and order of presentation are subject to change.
General Session I
June 23 (Monday Afternoon)
Session Organizer & Chairman: Harry J. Litsch, CEF-SE, H.J. Litsch Consultants, Inc., Bethlehem, PA
1 p.m.--Plating Development with Pourbaix Diagrams
Gene Calvert, & Dr. Burt Shah, Boeing Commercial Airplane Group, Wichita, KS
Pourbaix Diagrams have long been a method used to explore the thermodynamics of metal. They graphically show regions where the different metals tend to corrode or are stable. This is based on pH and redox potentials. In the past, these diagrams were presented in a static form that required many interpretations. Today, this technology has been married to the power of computers. With this marriage, these diagrams can be tailored to a specific application and become a very powerful tool for understanding electrochemistry. An acid chloride zinc-nickel alloy bath was refined with the use of this tool. These refinements include a tremendous increase in covering power, adhesion to stainless steel without a prior strike, and greater stability of the bath.
1:30 p.m.--Nuts & Bolts of Understanding Balance Sheets
Edward Kittridge, Hawkins International, Harvey, IL
The understanding of the basics of financial balance sheets and how the various aspects impact on businesses will be covered. Also to be discussed are facts that one needs to know when dealing with a banker and/or investor.
2 p.m.--Study on the Chemical Polishing Stain-less Steel
Professor Fang Jing Li , Wu Yong, Han Ke Ping Gul Technologies Singapore PTE LTD, Singapore
Influences of the solution components and operating conditions on the polishing effect during chemical polishing of stainless steel were studied quantitatively with reflective and gravimetric methods. The optimum polishing technology for stainless steel was obtained with a near mirror-bright surface.
2:30 p.m.--Pulsed Electrodeposition of Rough Copper Coatings
Professor Sergei S. Kruglikov, Dr. Sci., Dr. Michael M. Yarlykov & Lyudmila M. Velesevich,Mendeleyev University of Chemical Technology, Moscow, Russia
Copper was deposited from sulfate solutions by alternating high- and low-polarization pulses. In the former, cathode polarization was so high that very fast growth of microprotrusions and the formation of new microdendrites took place as the result of strong antileveling. In the latter, metal microdistribution was uniform, microdendrites thickened and attained the necessary mechanical strength. True surface area and, correspondingly, plastic-to-metal bond strength can be increased many times by depositing a thin microrough metal layer (e.g., copper) on the metal substrate. The deposit's morphology and adhesion properties were shown to depend mainly on the ratio of the quantities of copper deposited during high- and low-polarization pulses.
3 p.m.--Decorative Metallization on Plastics
Dr. Brent Lee & Youguang Liu, Vacuum Plating Technology Corporation, San Jose, CA
Increasing demands for a quality metallic finish over plastic products create a great opportunity for the vacuum coating industry. Over the years, the plastics industry has made many improvements. As a result, plastic products are now light in weight, strong, easy to mold into a desired shape, non-corrosive, and, most of all, low cost factors make plastic the material of choice. Al-though improved, many plastic products still maintain a cheap appearance. A major disadvantage of plastic products is that they deteriorate under ultraviolet light. High quality metal films coated over the plastic can overcome these draw-backs. A method for plasma synthesis of metallic film deposit on a plastic surface will be de-scribed. Cathodic Arc Plasma deposition, a branch of PVD technology, provides an efficient and economical way of producing metal plasma for deposition. In contrast to gaseous plasmas, the metal plasma ion sources are not produced by gaseous ionization, but by micro-explosions at the surface of the solid source material by cathode arcs in a vacuum chamber. The metal plasma deposition technique provides a means for pre-forming surface modification and material synthesis with a range of features and properties that could be valuable in many ways. For plastic substrates, care must be taken to block the heat generated by the vacuum arc source. Production-sized equipment is designed and built to apply metallic coatings to large substrate areas. Advantages are as follows: One-step coating process; super-strong adhesion; various types of metal sources to produce a variety of colors; and can coat complex shapes and large area substrates.
3:30 p.m.--Evaluation of Phosphatability of Steels by an Impedance Technique
Jeong-Real Park, Pohang Iron and Steel Company, Ltd., Chonnam, Republic of Korea
In this work, a phosphated steel surface has been examined by electrochemical impedance spectroscopy at its varying open-circuit potential with time in a neutral salt solution rather than by highly cathodic or anodic polarizations. Its impedance data have been analyzed by comparing with the results of bare surface to yield the surface coverage ratio of the phosphate coating and the charge transfer resistance through the inter-face. The ratio has been proved to be in good agreement with the observations by other methods so suggested to be substituted for conventional evaluations. The resistance has accounted well for the corrosion degradation of the interface.
4 p.m.--A Proposed Investigation into Aerosol Formation at the Surface of Open Tanks
Dennis R. Hanlon & Adam Chmielewski, KCH Services, Inc., Forest City, NC
Recent advances in laser spectroscopy allow researchers to gather data that was unobtainable and gain a detailed understanding of aerosol formation at plating tank surfaces. The focus of this paper will be to characterize emissions and investigate improved control devices for chromium solutions from open plating tanks using this technology.
June 23 (Monday Afternoon)
Session Organizer & Chairman: Myron Browning, CEF, Matrix Technologies, West Hills, CA
1 p.m.--High Speed Ni-W Alloy Electroforming
Professor Chein Llo Huang, Soochow University, Shin-lin, Taipei, Taiwan
Our earlier work showed that the internal stress of nickel or nickel-tungsten electroforms in-creased with increasing current density. There-fore, low current density is necessary to have a low-stress electroform. In this work, optimum organic additives with reduction group were added to the Ni-W electroforming bath to reduce the hydrogen content in the deposit at higher current densities, resulting in a lower internal stress at higher current density. A high-speed electroforming of Ni-W alloy was obtained.
1:30 p.m.--Electrodeposition of Fe-Ni-P Alloys for Wear Resistance
Professor Hetong Guo, Shulan Liu & Hui Liang, Tianjin University, Tianjin , Peoples Republic of China
Fe-Ni-P alloy coatings in which the Fe content is more than 90% can be deposited by adding NiCl2 and NaH2PO2 in an ordinary ferrous chloride bath. It was shown by experiments that the codeposition of Fe with ZP met some difficulties, but indicated deposition of P was easily carried out after a certain amount of Ni salt was added to the bath. These kinds of coatings have the properties of higher hardness, lower residual internal stress, and better wear resistance, when compared with general iron coatings.
2 p.m.--The Preparation of Ni-S Alloy by Electroplating Method
Professor Ruifang Zhuang & Ligong Jing, Nanjing University, Nanjing, Peoples Republic of China
Ni-S alloy containing from 17-23 (wt%) of sulfur was obtained in a weak acidic bath containing Na2S2O3 by electroplating method. The sulfur content and structure of the Ni-S alloy films were studied by SEM observation, X-ray diffraction and XPS. The results showed that films containing about 17-23 (wt%) sulfur consisted of a mixture of microcrystalline and amorphous alloy. Hydrogen overpotentials at Ni-S cathodes have been measured in 1N NaOH solution.
2:30 p.m.--Ecologically Safe Brightener Composition for Tin-Based Alloy Plating
Professor Andrei N. Popov, Mendeleyev University of Chemical Technology of Russia, Moscow, Russia
A new brightener composition for tin-based alloy plating is considered. It is compared to the latest inventions of the same type from point of view of ecology. The brightener is used without formaldehyde. An optimum bath's composition for POS-1 alloy plating and its computer model will be presented. The computer model of brightener bath realizes a 3D-simulation of the Electrodeposition. The scaled presentation of deposits' grain is based on the experimental data obtained with the aid of an electron microscope.
General Session II
June 24 (Tuesday Morning)
Session Organizer: Harry J. Litsch, CEF-SE, H.J. Litsch Consultants, Inc., Bethlehem, PA Session Chairman: Dr. Earl Winters, Consult-ant, Quakertown, PA
8 a.m.--Preliminary Evaluation of Electroplated Aluminum on Steel Substrates
Keith Cramer & J. Peter Ault, P.E., Ocean City Research Corporation, Ocean City, NJ
A non-aqueous electroplating procedure for the deposition of an aluminum coating has recently been commercialized in the United States, The corrosion resistance and some mechanical properties of aluminum-plated steel test specimens have been evaluated. Testing has included natural marine atmospheric exposure, salt fog exposure, fastener torque/tension, and paint coating adhesion. The performance of the aluminum coating material during these tests will be discussed. When applicable, the performance of the aluminum- plated panels will be compared to other coating materials that have been proposed as substitutes for cadmium plating.
8:30 a.m.--Electrochemical Surface Treatment of Stainless Steels
Dr. Rustem A. Kaidrikov & Professor Boris L. Juravlev, Kazan State Technological University, Kazan, Russian Federation
It is known that the electrochemical treatment of stainless steels by using solutions containing Pt or Pd ions provides the best corrosion resistance. Corrosion resistance of stainless steels depends on the content of Pt or Pd on the surface of the steel. In this paper, a new electrochemical regime is suggested that allows a decrease in the solution concentration of the alloyed ions (Pt and Pd) at constant corrosion resistance. For example, 18Cr10Ni stainless steel was electrochemically treated in a solution containing 5.85 g/L NaCl + 0.05 - 1.0 g/L PdCl2 and corrosion tested in 30% H2SO4.
9 a.m.--On the Kinetics of Chromium Electroreduction from Cr(III) Electrolyte
Professor V. N. Kudryavtsev, E. G. Vinkurov & V. V. Kuzentsov, Mendeleyev University of Chemical Technology of Russia, Moscow, Russia, & S. R. Schachamayer, Eaton Corporation, Milwaukee, WI
The aim of the present work was to understand why electrodeposition of chromium from the usual trivalent chromium baths ceases altogether after a certain time of electrolysis, but lasts in-definitely from a newly developed bath. Kinetics of Cr+3 ions discharged from a Cr(III) plating bath was studied by potentiostatic method. Limiting stages for the reduction of Cr+3 to Cr+2 and to metal chromium have been determined. In both cases, reaction rates for Cr+3 discharge are expressed by kinetic equations of mixed control (i.e., electron transfer and diffusion of Cr+3 ions are limiting stages).
The effect of the new bath pH on the rates of different reactions was investigated. At certain potential that corresponds to diffusion, c.d. of metal chromium stops and all the cathodic cur-rent is spent for hydrogen ion discharge, leading to the formation of chromium hydroxide. This potential changes from -1.32 to -1.28 V when the pH of the solution is increased from 1.4 to 1.8. This effect is ascribed to an increasing rate of OH- ions formation resulting from water molecules cathodic reduction. The results will be compared with ones received at studying a typical Cr(III) bath.
9:30 a.m.--Acceleration Mechanism of Thiourea for Electroless Nickel Deposition
Professor Fang Jing Li, Gul Technologies Singapore PTE LTD, Singapore
The influence of thiourea on the reduction rate of nickel and hydrogen were determined. The results indicated that thiourea can accelerate the reduction rate of Ni++ and H+ simultaneously, and decrease the activation energy. The anodic and cathodic polarization curves showed that thiourea does not affect the cathode process and only accelerates the anodic oxidation rate of H2PO s . The results of XPS and AES showed that the element composition of the Ni-P deposit (A.C. %) were Ni (75.8%), P (22.7%), O (0.1%), and S (0.4%), respectively.
10 a.m.--Abrasive Wear Resistance & Microhardness as a Function of Heat Treatment
Jim Harrison & Dr. Jean Rasmussen, Research & Development, Pioneer Metal Finishing, Green Bay, WI
The microhardness and abrasive wear resistance of EN-plated parts improves when heat-treated at high temperature. The temperature itself and the treatment time are two important parameters determining the end result. A three-dimensional correlation between heat-treatment conditions and the technical quality of EN-plated parts are not linear. This paper contains results from abrasive wear testing and microhardness of heat-treated EN-plated panels. The experimental design is based on statistical planning using Taguchi orthogonal arrays.
10:30 a.m.--The Effect of Phosphorus Distribution in Copper Anodes Upon Anode Sludging & Current Efficiency in Acid Copper Plating
Richard W. Strachan, CEF-SE, The International Metals & Chemicals Group, Shelby, North Carolina
Phosphorus distribution has been measured in copper anodes of various sizes and shapes manufactured by producers from around the world. Scanning electron microscopy reveals phosphorus segregation in all anodes, reflecting solidification and anode fabrication processes. Laboratory electroplating tests have been performed on these anodes to measure anode sludging and current efficiency. There appears to be little correlation between anode performance in plating tests and phosphorus distribution. This seems likely to be the result of the fine scale of the phosphorus variations relative to the phosphorus-copper film formation on the surface of the anode during the plating process. The acceleration mechanism of thiourea from the above results can attribute to the adsorption and interaction of thiourea and H2POs on the active metal surface. As the results show, the cleavage of the P-H bond of H2POs was accelerated and the electrons were easily transported to the metal surface through atomic S of thiourea and atomic H. Therefore, the reductions of Ni++ , H+ , and H2PO s on the metal surface were accelerated simultaneously.
11 a.m.--Utilizing Lead Assessor Training to Facilitate ISO 9000 Certification
Fred Mueller, CEF, Pottstown Plating Works, Inc., Pottstown, PA & William Stokes, Hood & Co.
Many surface finishers have customers who have obtained International Standards Organization (ISO) certification. Lead Assessor training is a key function for a member of the quality department of an ISO-dedicated facility in obtaining and maintaining ISO certification. Pottstown Plating Works customers have key people in their organizations trained or in training as Lead Assessors. Surface finishers can benefit by opening their facilities to peer review that is part of the training required to become a Lead Assessor. Finishers and their customers can assist each other by helping the finisher's quality department conform to ISO standards. This paper presents a case study of the cooperation in an ISO-audit/ peer review of Pottstown Plating Works, Inc., by William C. Stokes of Hood & Co.
Electronics Finishing I
June 24 (Tuesday Morning)
Session Organizers: Linda Mayer, Lucent Technologies, Inc., Murray Hill, NJ, & James M. Meade, Fidelity Chemical Products, Newark, NJ Session Chairman: Linda Mayer
8 a.m.--Critical Evaluations of Lead-Free Solder Alloys & Performance Comparisons
T. T. Hitch, K. Palif & A. N. Prabhu, David Sarnoff Research Center, Princeton, NJ
The David Sarnoff Research Center has conducted extensive evaluations on lead-free solders during the last three years. The approach was to review many of the potential lead-free solders and to select those for which were calculated a higher weighted sum of desirable property values. By this means, we initially selected six solders. Solder pastes were prepared of those alloys, along with crucible melts. Experimental evaluations included solder wettability as a function of temperature and flux activity, fatigue resistance (thermal and isothermal), and melting point determinations.
The principle solder alloys studied experimentally included the following: 96.5Sn-3.6Ag, 92Sn-3.5Ag- 4.5Bi, 90Sn-7.5Bi-2.0Ag-0.5Cu, a Sn-AgCu alloy, 42Sn-58Bi, and 99.5Sn-0.5Cu. Throughout the work, 63Sn-37Pb was used as a control. (All comparisons are in wt. pct.) The work also included limited experiments on three Zn-containing alloys: 91Sn-9Zn, 66.5Sn-31.5Bi-3Zn, and 95.5Sn-3.5Ag-1Zn. This paper discusses the methodology for solder alloy selection, solder preparation processes, test selection, results, and conclusions.
8:30 a.m.--Throwing & Covering Power Evaluations of a Tin Electroplating Chemistry by Hydrodynamically Controlled Rotating Cylinder Throwing Power Electrodes and Hull Cells
Y. Zhang, F. Humiec, K. Murski, I. Kadija & J. A. Abys, Lucent Technologies, Murray Hill, NJ
Throwing power and covering power are important properties of an electroplating chemistry. Throwing power has been determined by theoretical calculations and empirical methods. Equipment such as the Haring-Blum cell is available to evaluate throwing power for different plating solutions. It has some limitations, however, which mostly result because of low agitation rates and irreproducible hydrodynamic conditions.
Hydrodynamically controlled rotating cylinder throwing power electrodes (RCTPE) and Hull cells (HCHC) were developed recently to overcome the limitations mentioned above. Both provide a wide range of agitation and reproducible hydrodynamic conditions. Utility of RCTPE and HCHC is demonstrated by applying them to an electroplating tin chemistry. Results will be presented in detail in comparison with conventional approaches.
9 a.m.--Uncertainty Estimation in Layer Thickness Analysis by XRF
& Optical Cross Section
Glenn E. Staudt, AMP Inc., Harrisburg, PA
Understanding of uncertainty is requisite for proper interpretation of results from coating thickness analysis. This has practical consequences for process control, product disposition, and measurement correlation. Traditional assessments typically exclude major sources of uncertainty, however. Consequently, detailed theoretical development is undertaken for two common methods: X-ray fluorescence and optical observation of cross sections. Many sources contribute to uncertainty of x-ray results, but the effect of calibration predominates under many practical circumstances. The uncertainty of optical measurement of thin coatings is dominated by the inherent precision of optical observation. These theoretical treatments are confirmed by empirical results.
9:30 a.m.--Control of Electroforming Solutions by Stripping Voltammetry
P. Bratin, G. Chalyt & M. Pavlov, ECI Technology, East Rutherford, NJ
One of the key parameters in controlling mechanical properties of an electroformed deposit is the concentration of organic additives. High current density and operation temperature cause the rapid breakdown of additives, which requires their continuous replenishment. The additives employed for electroforming are usually natural multi-component products (derivatives of gelatin, cellulose, etc.) that undergo multiple transformations during the plating process. It is hardly feasible to determine separately the absolute concentration of each individual component. Be-sides, such information will have no practical use because the replenishment is done with pre-mixed additives.
The alternative way is to measure the effective concentration of additives in the production solution through their effect on the plating process. CVS (Cyclic Voltammetry Stripping) is a well-known analytical technique for control of additives in PCB plating. This paper will discuss a new application of CVS technique for the monitoring of organic additives in electroforming solutions. Results of analysis of both synthetic and production solutions will be shown. Application of CVS for the kinetic study of additive break-down will be discussed.
10 a.m.--Low-boron Electroless Nickel Plated Through-hole Process for Printed & Flexible Circuit Application: Advancements in Quality, Productivity & Reliability
Frank Cane, Dr. Saad Doss & Hiroyuki Ikeda, Fidelity Chemical Products Corporation, Newark, NJ
Low-boron electroless nickel can be used to provide through metallization amenable to the electrolytic copper process. The Ni-B deposit has physical and electrical properties characteristic of conventional electroless copper processes with the absence of environmentally hazardous formaldehyde. Practical application of low-boron electroless nickel through-hole metallization has been demonstrated in the fabrication of both rigid and flexible circuits compared to conventional electroless copper and direct metallization processes. It has been confirmed that the low-boron electroless nickel through-hole metallization process exhibits improved electrical resistivity, surface-to-hole electrolytic plating ratio, thermal stability, and reliability in comparison to the carbon-based direct metallization process.
10:30 a.m.--Electroless Copper Metallization on Ceramic Circuit Substrates
Xia Chuan Yi, Senior Engineer, The 13th Research Institute of the Ministry of Electronics Industry, HeBei, Peoples Republic of China
Electroless copper metallization technology for ceramic circuit substrates that has advantages for both thick and thin film processes has been developed. The etching behavior of ceramic substrates was studied by SEM. The adhesion strength, sheet resistance, thermal conductivity, and loss at microwave frequencies were determined. Furthermore, temperature cycling, aging, and other reliability tests were performed. The results of the tests and application show that, by using this technology, copper circuit patterns with strong adhesion can be fabricated onto alumina ceramic substrates, with excellent mechanical, electrical, thermal performance, and good reliability, which opens a new way for metallization technology of microwave and hybrid IC substrates
Light Metals Finishing I
June 24 (Tuesday Morning)
Session Organizers: Patrick Scalera, Parker+Amchem, Madison Heights, MI & Charles Grubbs, CEF, METALAST International, Minden, NV
Session Chairman: Charles Grubbs, CEF
8 a.m.--Using Casting for Surface Treatment (CAST) on an Al-Mg Alloy
Anne Deacon Juhl, M. Sci. & Per Møller, PhD, Technical University of Denmark, Lyngby, Denmark
The term cast is used to see the correlation in casting condition and anodizing behavior on an Al-Mg alloy. The sand-cast Al-Mg alloy is anodized, and afterward the microstructure and oxide is examined to see how this alloy is behaving in relation to a sand-cast aluminum-silicon alloy. Also, the voltage-time response is compared for the two alloys. The corrosion resistance of these oxide layers is investigated by atomic spectrophotometry to see which one gives the best result.
8:30 a.m.--Aluminum Wire Enameling: A New Surface Preparation
J. S.. Safrany, Pechiney, Voreppe, France, & G. Golombler & B. Loreau, Aluminum Pechiney, Paris, France
In many applications where the weight is an important factor, aluminum has proved to be a good solution. In the electrical industry, for example, aluminum has successfully replaced cop-per in many cases. In addition, new surface treatments have helped to penetrate some markets, such as enameled wire for electrical windings. This paper will present a new surface preparation for aluminum wire. This high-speed and easy-to-use process simultaneously removes wiredrawing soils from the wire and prepares the surface for enameling. It allows for excellent bonding of enamels, better than with conventional cleaning processes.
9 a.m.--Metal Quality and Finishing
Richard W. Mahn, Novamax Technologies (U.S.), Inc., Atlanta, GA
Metal quality prior to finishing of any aluminum product cannot be over stressed. This is a constantly growing problem as costs have been pushed downward, production rates have been pushed upward, and more sources exist for metal in a free world environment. This competition has created difficulty in obtaining high-quality, consistent and uniform metal. This paper will discuss the principal quality needs of the various types of fabricated products requiring some kind of finishing, whether sheets, extrusions, or cast parts, and whether anodized, painted or plated. The success of the finish is directly dependent upon the quality of the metal surface to be treated. While proper surface pretreatment is crucial, it highlights the actual superficial and/or internal structural characteristics of the base metal. The significance of this result on the final appearance of whatever finish is used cannot be stated too often or too vigorously.
9:30 a.m.--Solution Agitation in Sulfuric Acid Anodizing
Donald G. W. Ytterberg, Swiss Lenox, Inc., Arvada, CO
For 29 years, we have used mechanical mixers to provide solution agitation for Type II and Type III anodizing tanks. In 1996 we installed new Type II and Type III anodizing systems. Stainless steel heat exchangers have replaced lead cooling coils, aluminum cathodes have replaced lead plate, and eductor agitation systems have been installed to provide solution agitation. Simultaneously, constant voltage anodizing has been replaced by constant current anodizing using a proprietary process. This paper explains the steps needed to design and install a solution agitation system with consideration given to anodizing with high current density.
10 a.m.--Additives and Type III Anodizing-- Fact or Fiction?
Dr. Jean Rasmussen, Director/Research & Development, Pioneer Metal Finishing, Green Bay, WI
Heat production during anodizing is closely replated to the coating quality. The functionality of anodizing additives are endothermic reactions, which adds an extra heat-removing mechanism to the total process complexity. The use of additives is always correlated with some other functional changes of the anodizing conditions; very often both process temperature and the content of sulfuric acid are changed. Therefore, it is natural to ask: Are quality improvements really caused by the additives? This presentation contains results from anodizing under various temperatures and concentrations of sulfuric acid, with and without additive. It will be shown that some of the quality improvements claimed to be caused by the additive, can be obtained by just changing temeprature and sulfuric acid concentration.
10:30 a.m.--New Electrolytic Two-Step Coloring Process
Chris Hanthorn, Novamax Technologies (U.S.), Inc., Atlanta, GA
The process of two-step electrolytic coloring has long been commercially popular because of its durability, economics and ease of operation. The process has distinct cost advantages over integral coloring processes and has superior outdoor durability over organic dyeing or over-dyeing processes. The two-step electrolytic process, how-ever, has been limited in the range of colors it can offer. Traditionally, the only stable colors have been in the champagne to black range. Today's technological advances have enabled the offering of a rainbow of colors in a wide range of finishes. The main advantage of these new colors is their durability. These new finishes will not fade, peel, chalk, or corrode as organic dyes and paints often do.
This paper will discuss the new two-step coloring process and compare it to the traditional two-step electrolytic processes in terms of ease of operation and performance characteristics. The advantages over organic dyeing, enabling these new colors to be used outdoors, will be highlighted.
Light Metals Finishing II
June 24 (Tuesday Afternoon)
1 p.m.--Seal Performance Standards & Specifications for Anodized Aluminum
Anthony Ita, Henkel Novamax Technologies (US), Inc., Atlanta, GA
Several specifications and performance standards are utilized to evaluate seal quality in the aluminum anodizing industry. This article reviews existing test protocols and performance mandates designed to predict field reliability. A Relevance Index Analysis criteria is presented as a comprehensive and effective quality assurance program for consistent field performance.
1:30 p.m.--Microbump Formation on Aluminum Substrate
Takeshi Kobayashi, Hideto Watanabe & Hideo Honma, Kanto Gakuin University, Kanagawa, Japan
Fabrication of nickel bumps on an aluminum electrode with direct electroless nickel plating process has been investigated. Electroless nickel deposition with hypophosphite as a reducing agent is not started on the aluminum substrate (does not have a catalytic action). Accordingly, nickel is initially deposited on the aluminum using nickel displacement plating for the initiation of electroless nickel plating. Activation of the aluminum surface is also an indispensable process to initiate the electroless nickel plating. Uniform bumps on the aluminum can be obtained by electroless nickel plating after being activated with DMAB. Furthermore, nickel bumps can be obtained without photoresist.
2 p.m.--Non-Chromium Conversion Coating Technologies for Aluminum Alloys
Shawn E. Dolan, Lawrence R. Carlson, CEF, Parker+Amchem, Henkel Corporation, Madison Heights, MI
This paper will present new conversion coating technologies for treating aluminum alloys for both bare and painted surfaces. Examples of commercial applications in various industries, such as aluminum wheels, aerospace, extrusions, and marine applications, will be discussed.
2:30 p.m.--Chemical Recovery Systems for the Aluminum Anodizer
Paul Pajunen, P. Eng, ECO-TEC, Inc., Pickering, Ontario, Canada
Although anodizing wastes are relatively simple to treat, many plants use recovery equipment to reduce costs. Two recovery techniques that are commonly used regenerate the etch and purify the anodizing acid. This is due, in part, to the large amount of solid waste (aluminum hydroxide sludge) that etching and anodizing generates. Recycling this waste reduces chemical costs and, frequently, improves product quality.
Regeneration of caustic soda etchants can dramatically reduce an anodizing plants' solid waste by more than 80% while lowering caustic soda usage by more than 70%. The alumina crystals that are removed can be put to a variety of uses as an alumina substitute. Sulfuric acid anodizing acids are considered spent and need to be discarded when they reach a certain level of aluminum contamination, even though they may still contain unused free acid. Recovery of this free acid has been practiced for a number of years in a variety of applications. A popular method of acid recovery employs a process called acid sorption. This presentation will review the etch regeneration and acid sorption processes; outline critical design features; and provide field performance data and operation experiences.
3 p.m.--Nickel is Class
Ralph V. Dixon, MacDermid, Inc., East Berlin, PA
There is a new demand for high-quality nickel and chromium finishes on aluminum, brought about by the cast automotive wheel and motor-cycle industries. Satisfying these demands is not as easy as one might imagine. We will explore the requirements, problems, and some of the corrective measures required to produce these class finishes.
3:30 p.m.--Aluminum New Developments: Anodizing Methods - Hard Anodizing and Integral Color --Electrocoloring
Dr. Xavier Albert Ventura, Integral Centre of Barcelona Spain, Barcelona, Spain
Some statistics of aluminum consumption will be given for conventional anodizing. Sulfuric acid, oxalic acid, chromic acid, integral and hard anodizing, modulated current anodizing for thyristor controlled rectifiers, electrocoloring topics of sealing hot and cold, electrophoretic and dip painting will all be discussed. Some novel applications, such as solid-type lubrication, pre-coated finishings and functional uses for electronics (in which Spain and the European Community are fairly advanced) will be introduced. Finally, applications of an alpha-alumina coating will be reviewed.
Electronics Finishing II
June 24 (Tuesday Afternoon)
Session Organizers: Linda Mayer, Lucent Technologies, Inc., Murray Hill, NJ & James M. Meade, Fidelity Chemical Products, Newark, NJ
Session Chairman: Chwan-Tsann Wang, Lucent Technologies, Inc., Holmdel, NJ
1 p.m.--Surface Finish Requirements for Advanced Bonding Techniques
James P. Langan, Langan Associates, Red Bank, NJ
The high I/O interconnections required by recent innovations in component technology are causing electronic manufacturers to re-evaluate existing assembly techniques. As 0.4 and 0.3 mm pitch pads become customary, the presently preferred MO of applying solder paste to hold components in place prior to reflow soldering may no longer be yield or cost-effective. Prevalent practices for attaching components to hybrid circuits (thermocompression, thermosonic, ultrasonic, and eutectic bonding) could yield the answer for attachment of ultra-fine pitch components to printed circuits.
Surface finishes currently employed or being investigated for these bonding procedures are tin, silver, nickel/gold, and nickel/palladium. This paper details advantages/disadvantages of electroless and electroplating processes and attempts to clarify the pragmatism of selective finishes to maximize applicability when several attachment techniques are required to obtain high first-pass yields.
1:30 p.m.--Study of a Very Stable Alloy-Ratio Deposit from Different Current Density Areas in Palladium-Nickel Electrolytic Deposition
Kazuyoshi Okuno, Okuno Chemical Industries Company, Inc., Osaka, Japan
2 p.m.--Applications of Electroless & Electrolytic Palladium in PWB Manufacturing
Bruce Stacy, I. V. Kadija, L. J. Mayer, C. Pan, J. A. Abys & H. K. Straschil, Lucent Technologies, Murray Hill, NJ
The emerging demand for surface-mounted components and the increasing cost of environmental compliance encourages the PWB industry to evaluate new surface finishes. The requirements include: uniform thickness distribution, solder-ability, bondability, non-lead bearing, environ-mentally acceptable and economically favorable. Palladium meets all these requirements and more. Palladium plating processes are production proven in connector and semiconductor packaging applications. This paper will describe how palladium can simplify and improve the manufacture of printed wiring boards. Characteristics of both electrolytic and electroless palladium processes and their deposit properties will be presented. Emphasis will be placed on solderability and wire bonding results before and after accelerated age testing.
2:30 p.m.--Surface Evaluation of the Silver Finishes via Sequential Electrochemical Reduction Analysis
P. Bratin, M. Pavlov & G. Chalyt, ECI Technology, East Rutherford, NJ
Currently, tin/lead and gold coatings are the main metal finishes employed in the manufacturing of the printed circuit boards, providing protection of the substrate from oxidation and successful wire bonding. With the industry trend to miniaturize the interconnections, both printed circuit board fabricators and assemblers are searching for the lower cost alternatives. One of the commercially available alternatives to these finishes is an immersion silver coating coupled with an extremely thin organic film. Because the silver can be tarnished in the production environment, the monitoring of the surface conditions is one of the major concerns for soldering and wire bonding. Sequential Electrochemical Reduction Analysis (SERA) was developed for the solderability assessment of tin/lead coatings, and later has been extended to the identification of the oxides and other reducible species, as well as the measurement of their thicknesses. This paper will discuss the new application of the SERA technique to assess the surface conditions of the silver finish. The tarnishing products of the silver formed under ambient and artificially created conditions will be analyzed. The protective effect of an anti-tarnishing film will be evaluated. The influence of the elevated temperatures (reflow) on the stability of the organic inhibitor and the formation of the tarnishing film will be shown.
3 p.m.--Ductile Nickel/Palladium Multilayer Surface Finishes Designed for Leadframe Packaging
Dr. Chonglun Fan, V. Kadija, J. A. Abys & J. J. Maisano, Lucent Technologies , Murray Hill, NJ
Electrolytic palladium surface finishes have been continuously improved for leadframe applications. Today, these finishes can be employed at costs comparable to tin-lead surface finish with extra advantages, such as superior functional performance and considerable environmental impact reduction. In our developmental efforts, we have optimized the palladium multilayer surface finishes in both functional and environmental aspects by introducing a ductile nickel underplate. Functionally, the solderability of the leadframes are dramatically increased compared with using typical nickel plate. High solder coverage and wetting speed are maintained on crack-free surface finishes after trim-and-form operations and steam or thermal aging. Environmentally, the need for activated fluxes is eliminated in assembly. This significantly reduces the solvent and rinsing requirements and minimizes contamination. In this paper, we will introduce our recently obtained solderability and wire bonding results on the palladium pre-plated leadframes and com-pare them with the leadframes plated with typical nickel coating.
Waste Treatment & Recovery I
June 24 (Tuesday Afternoon)
Session Organizer & Chairman: Thomas Baker, Kinetico, Newbury, OH
1 p.m.--Zero Discharge in the Metal Plating Industry Using an Improved Ion Exchange Process
Juzer Jangbarwala, Hydromatix, Inc., Chino, CA
A recent pollution prevention assessment of California's metal plating industry showed that businesses are implementing or researching technologies to "close the loop" on their rinsewater systems and to achieve zero water discharge to the sewer. According to this assessment, ion exchange technology is one of the preferred technologies to achieve "closed loop" conditions. Unfortunately, the traditional ion exchange process does not economically achieve "zero water discharge" because the regeneration of the spent resin beds produces a significant quantity of hazardous aqueous waste. This aqueous waste is typically treated and discharged to the sewer. The rinsewater recycling system discussed in this paper combines various aspects of ion exchange and evaporation to achieve zero water discharge. Although ion exchange and evaporation are not new technologies, the ion exchange regeneration process has been improved by reusing portions of the regenerants. The reuse of regenerants drastically reduces the volume of generated aqueous wastes.
1:30 p.m.--Automated Waste Treatment
Stephen Koelzer, K & K Products, Sunnyvale, CA
Physical and chemical changes invariably follow established laws. Just as with plating, changing (mixed aqueous) wastes states has empirically graduated into science from art. Precipitation/ adsorption of cations/anions can be effected by the same reactant. Therefore, separation by differential crystallization, speciation of crystal forms (by manipulating valence states) and less-than- equilibrium discharges are achievable within the same tank. Crucial to processing is endpoint detection. Instrumentation is used to efficiently control/automate treatment/purification, recycling, reclamation. Results are facile solids settling/ filtration/dewatering, minimized POTW loading and toxicity reduction. Applications are cited from photochemical machining, aluminum, printed circuit board, nickel and cyanide waste streams processing. Wastes may now follow a simple programming decision tree as fundamental methods and techniques have become integrated.
2 p.m.--Technical & Economic Aspects of Electrochemical Regeneration of Zinc Chromating Solutions
Professor Sergei S. Kruglikov, Dr. Sci., Mendeleyev University of Chemical Technology, Moscow, Russia, & Dr. Vasili V. Okulov, AVTOVAZ, Togliatti, Russia
All chloride-free chromate solutions can be re-generated electrochemically. Dissolved zinc is completely recovered, trivalent chromium is re-oxidized to chromate and acidity (pH) of the solution is restored. Batch operation is possible, but continuous process is preferable because it allows the maintenance of constant solution composition and properties of the chromate films. The regeneration unit occupies 0.5 to 1 m 2 of floor space or is placed directly inside the chromating tank close to one of its walls as a compact (10-15-cm thick) electrochemical module. Savings were more than $10,000 p.a. for one 500-gal plating tank with a black zinc chromating solution. (Evaluation was based only on the cost reductions resulting from the elimination of making up fresh solutions every five weeks.)
2:30 p.m.--Water Recycling at Hughes Missile Systems Company
Paul W. Fecsik, Hughes Missile Systems Company, Tucson, AZ
This paper discusses a plant-site water recycling system in use that services a large number of customers with varying water quality needs-- PWB shop, general finishing shop, prototype shops, and maintenance area (scrubber systems, air handling systems). Approximately 90% of the water is continuously recycled. Elements of the system include an industrial waste treatment plant (IWTP) that produces a reclaimed water product suitable for most areas of the plant, a deionization area to supply higher purity water, and local metal removal and deionization systems within process shops for chrome and nickel removal with deionization for in-process recycling (cop-per, tin and lead systems planned for 1997).
3 p.m.--Electrolytic Capture & Recycle of Ni & Zn from Plating Waste
Professor David H. Swenson, Bruce Hart,Michelle Vogtmann, Professor Albert Plausch, Professor George W. Eastland, Jr., Kevin Wiese & Tom Vivian, Saginaw Valley State University, University Center, MI; & Kevin T. Jungquist, Tawas Plating & Powder Coating Company
Saginaw Valley University, in collaboration with Tawas Plating and Powder Coating Company, has recently initiated a project funded by the Michigan Department of Environmental Quality on methods for electrolytic capture of Ni and Zn wastes from plating solutions. A split cell design was previously found to be optimal for capture of Ni, and preliminary studies suggest that a single cell for Zn capture may provide optimum capture. Because market price for scrap Ni and Zn is relatively poor, we are investigating the economics of dissolution of the metals to their sulfate forms for reincorporation into the plating baths.
3:30 p.m.--Chemical Conservation/Waste Minimization
Paul G. Page, P.E., TOLTEST, Inc., Plymouth, MI
Many facilities in the electroplating and surface finishing industry have implemented techniques to reduce rinse water consumption and wastewater discharge. These techniques include spray rinsing and counterflow rinsing. These methods do not reduce chemical losses resulting from drag out, concentration of wastewater contaminants, chemical usage for wastewater treatment, and wastes generated from wastewater treatment, however. Chemical conversion and waste minimization can be achieved through in-line modifications of electroplating and other surface finishing operations. The cost savings resulting from reduced chemical usage and waste disposal can offset the capital costs of installing these modifications within 1 to 2 years. Finally, a means of being environmentally conscious can be a way to save money.
4 p.m.--Legislation for the European Community on Waste Characteristics: Lixiviation Tests for Electroplating Muds
Dr. Xavier Albert Ventura, Integral Centre of Barcelona Spain, Barcelona, Spain
Industrial waste is subject to two categories of test for lixiviation of extraction: Dynamic and static tests. The first one is adequate to predict waste behavior at long-term deposition sites, taking into consideration that study of the lixiviation speed of its components is determined by the chemical properties, which includes factors determining the contaminating agents' solubility and by the transport properties that affect the ions' diffusion in the solid, as well as the hydro-dynamic system. This study is centered on the static lixiviation tests, given the fact that this is the most usual mechanism for the different legal frames to characterize and identify an industrial waste as a dangerous and toxic waste (RTP). These type of extraction tests essentially consist in putting the waste in contact with an extractor fluid in a high relation liquid/solid (waste) by means of a vigorous agitation during a defined time at room temperature.
Electronics Finishing III
June 25 (Wednesday Morning)
Session Organizers: Linda Mayer, Lucent Technologies, Inc., Murray Hill, NJ, & James M. Meade, Fidelity Chemical Products, Newark, NJ
Session Chairman: James M. Meade
8 a.m.--The Trend Toward Pd/Ni Contacts in High Density Interconnects
Lawson Williams, Ranoda Electronics, Inc., Miami, FL
Quality is the number-one requirement for high-density interconnects, but competitive cost reduction is the second most important factor. Explosive growth in demand for high density connections in personal computers, disk drives, and communication products is moving connector suppliers to shift from hard gold plating to state-of-the-art palladium-nickel contact faces with a low-cost gold flash. For high density interconnects with contact pitches as close as 1 mm for use in surface mount products, the benefits of palladium-nickel contacts can be superior to hard gold. Fully 85% of Ranoda's products now use Pd/Ni contacts. This paper reports on the three trends: The use of Pd/ Ni for high-density interconnects in low-cost, high-end products; concurrent team efforts among connector specifiers, connector suppliers, and material suppliers; and the development efforts toward even lower-cost materials, including cobalt.
8:30 a.m.--Extended Thermal Aging of Precious Metal Finishes Used in Automotive Connectors
Gerald R. English & Therese R. Souza, Handy & Harmon, North Attleboro, MA The contact resistance of cobalt-hardened gold, nickel-hardened gold, gold-flashed palladium, and gold-flashed palladium-nickel before and after thermal aging at 135 o C was measured. Con-tact resistance readings were taken at 0, 1,000, 2,000, and 3,000 hr at loads ranging from 0.49 to 2.94 Newtons (50 to 300 gf). The total precious metal thickness was less than one micron. The porosity of the samples was measured with standard porosity testing techniques. The surface chemistry was examined before and after aging. Additionally, Auger electron analysis was conducted after sputtering 25 nm into the surface on samples that were aged 3,000 hr. This paper will discuss causes of observed changes in contact resistance.
9 a.m.--Palladium-Nickel Electrodeposits-- Properties & Selection
Michael Toben, LeaRonal, Inc., Hauppauge, NY
Palladium-nickel alloy electrodeposits comprising between 70 and 85% palladium are becoming increasingly accepted as viable connector finishes. Within this range of alloy compositions, notable differences in the metallurgical and functional properties of the deposit exist. The current work describes the influence of alloy composition on deposit grain structure, wear resistance, internal stress and ductility as a means to assist the user in selecting the best composition to satisfy a particular end-use requirement. A historical review of electrodeposited palladium and palladium alloys in the electronics industry is also presented.
9:30 a.m.--New Pd/Ni Plating Bath: Chemically Benign & Environmentally Friendly
Irina Boguslavsky, J. A. Abys, H. Straschil, J. J. Maisano & V. Eckert, Lucent Technologies, Murray Hill, NJ
Most conventional Pd and Pd/Ni plating chemistries contain ingredients that make them very corrosive towards base metals and stainless steel components. Typically, they also operate at high pH, which causes strong chemical odor and requires frequent pH adjustment. This can make the Pd plating process costly and environmentally hostile. A new Pd/Ni plating chemistry was designed with the objective of reducing the bath corrosiveness towards stainless steel and copper alloys, decrease chemical odor and ph adjustment. Characterization of the bath is presented in the paper. The effect of the bath components and plating conditions on Pd/Ni alloy composition and material properties is described. The bath plates Pd/Ni deposits with excellent appearance, ductility, corrosion and wear resistance. The chemistry causes negligible corrosion of stain-less steel and copper; it has practically no chemical odor and requires minimum pH adjustment. The material properties of the Pd/Ni deposits plated from this bath are demonstrated as well.
10 a.m.--Switch-mode Power Supplies & Their Application in the Electroplating Industry
Peter Cambria, Rapid Power Technologies, Inc., Brookfield, CT
High power switch mode power supplies have been available for more than 15 years, but their primary use was for the semi-conductor testing industry. Only recently--within the past four years--have manufacturers begun selling them as an alternative to other power supplies in the electroplating market. The advantages of this type of unit are many, including: Smaller size, less weight, extremely low ripple, and precise regulation.
There are drawbacks, however, to taking equipment primarily designed to be used in clean, air-conditioned rooms and putting it in a plating atmosphere. The second generation of switch mode power supplies, totally sealed and designed specifically for the corrosive atmosphere of a plating shop, is now available, with many state-of-the-art features.
WINDOW OF OPPORTUNITY
Wednesday, June 25
11 a.m.-2 p.m.
No papers scheduled; Please visit the exhibit.
Environmental Technology In Latin America
June 25 (Wednesday Morning)
Session Chairman & Workshop Leader: Peter A. Gallerani, CEF, Integrated Tech., Inc., Danville, VT
8 a.m.--Opportunities in the Metal Finishing Markets of Brazil
Brazil and Mexico are major centers of the metal finishing industry, accounting for more than 8 billion of annual output -- even excluding the automotive sector. Metal finishing industries in these countries are in rapid transition as they face fierce world-wide competition, falling tariff barriers and pressures from new health, safety, and environmental regulations. These challenges are driving demand for new equipment, processes, services, and investment. This workshop will assist U. S. suppliers to participate in these markets by providing information about available opportunities and practical advice. The workshop will include representatives from the metal finishing industries of Latin America, as well as experienced U. S. practitioners, who will share their knowledge and outline strategies for penetrating these major markets.
The "Corrosion in Electronics" Session, scheduled for Wednesday afternoon and organized/chaired by Dr. I-yuan Wei, AMP, Inc., Harrisburg, PA, is dedicated to the honor of Richard E. Baker, CEF-SE, of Baker Consultants, Winter Springs, FL. Mr. Baker's career of more than 40 years in the telecommunications industry focused on the study of corrosion in electronics. He is a technical specialist for educational development for the AESF and has been one of the Society's key instructors, organizers of technical conferences, and author/reviewer of educational materials for more than 17 years. He received the AESF Order of Past Presidents' Award in 1989.
Corrosion in Electronics
June 25 (Wednesday Afternoon)
Session Organizer & Chairman: Dr. I-yuan Wei, AMP, Inc., Harrisburg, PA
This session is dedicated to the honor of Richard E. Baker, CEF-SE, of Baker Consultants, Winter Springs, FL. Mr. Baker's career of more than 40 years in the telecommunications industry focused on the study of corrosion in electronics. He is a technical specialist for educational development for the AESF and has been one of the Society's key instructors, organizers of technical conferences, and author/reviewer of educational materials for more than 17 years. He received the AESF Order of Past Presidents' Award in 1989.
1 p.m.--Corrosion in Electronics--A Historical Perspective
Richard G. Baker, CEF-SE, Baker Consultants, Inc., Winter Springs, FL
Over the years, electronic devices and equipment have been shown to be susceptible to the deleterious effects of a wide variety of atmospheric contaminants. This paper will give the results of number of investigations associated with those corrosion- related failure mechanisms that the author has found electronic devices to be susceptible. It is hoped that these may serve to alert the finisher to the types of corrosion-related problems he or she may not have considered. The effects of a number of environmental contaminants on the unexpected premature corrosion induced failures in electronic equipment and/or devices will be discussed from a historical perspective. The remedial actions necessary to prevent such failures are also addressed.
1:30 p.m.--Properties of Electroless Nickel Deposits: Specifying
& Measuring Problems
Dr. Jack Horner, Milford, MI, & Brad Durkin, MacDermid
In specifying EN deposits, it should be recognized that the properties of the deposits can vary widely with the phosphorus content, along with other less well-known factors. It also should be recognized that the measurement of these proper-ties is subject to wide variations, some known and some less well-known. This paper discusses some of the experiences of the authors in the use of some of these test methods. Among the test methods discussed are microhardness, corrosion resistance and the resistance to the salt spray (fog) test, ductility, tensile strength, bend tests, and internal stress tests. Those who specify, produce, or use electroless nickel deposits should find this of interest.
2 p.m.--Corrosion of Joints Used in Electronics
Dr. Richard Haynes, Richard Haynes Consult-ants, Princeton, NJ
Plating and surface finishing technologies are essential to the electromagnetic compliance industries (EMC). One of the most common failure modes in electronic products is corrosion of the joints between conductive materials. Galvanic corrosion of these joints can cause electromagnetic interference (EMI), electrostatic discharge (ESD), electrical overstress (EOS), and increase susceptibility of electronic products to externally generated electronic noise. This paper reviews the conductive materials and surface finishes commonly used in making joints and the technical principles used in the proper choice of materials, discusses design guidelines for joints that should be used in electronic products, and summarizes implications regarding the selection of conductive materials and surface finishes that could increase the life of the electronic products. New developments are needed in plating materials and surface finishes in present and future electronic products.
2:30 p.m.--Practical Aspects of Porosity Testing of Electronic Contacts
Robert A. Michelson, AMP, Incorporated, Harrisburg PA
Numerical values of pore counts are not as significant as determining the root causes of the porosity and applying the knowledge to improve the manufacturing process. This paper will deal with the porosity testing process and how to apply failure analysis to determine the root cause of the porosity. Comparisons between different porosity test methods and the need to have well-trained porosity test technicians will be discussed.
3 p.m.--Corrosion Control for Metallized MCMs & Hybrid Circuits
Donald W. Baudrand, Consultant for MacDermid, Inc., Waterbury, CT
Corrosion is defined and described for electronic devices. The results of corrosion, including oxidation, loss of contact resistance, current leak-age, shorts, and diffusion changes in hybrid circuits are discussed. Diffusion of metals resulting in nickel, copper, or silver in the surface layer which corrode or change the surface characteristics is discussed. Diffusion barriers and corrosion protection methods are suggested.
3:30 p.m.--Enhanced Solderability of PWB Substrates with Improved Organic Solderability Preservatives (OSP)
Michael Carano, Electrochemicals, Inc., Maple Plain, MN
A critical success factor in achieving sufficient solderability of surface mount and through de-vices is the ability to preserve the solderability of the surface finish. OSPs have been known to provide excellent protection against the oxidation of the base metal. There are concerns from assemblers and bare board fabricators, however, that these coatings are not capable of maintaining sufficient solderability of the base metal on multiple thermal pass assembling operations such as required by mixed technology boards. Other concerns relate to the consistency of the applied coating during normal processing, as well as the actual thickness of the OSP. Compatibility with no clean fluxes is also a major requirement. This paper will address these and other concerns, including the electrical testing considerations, reliability, shelf life/solderability retention under aging conditions, and compatibility with the soldering operation and soldering materials.
June 25 (Wednesday Afternoon)
Session Organizer & Chairman: Dr. James H. Lindsay, Jr., General Motors Research Laboratories, Warren, MI
1 p.m.--Electroplating of Thin Films of Zn-Ni- SiO 2 Composites onto Steel to Prevent Corrosion & Hydrogen Embrittlement
Professor Branko N. Popov, M. Ramasu-bramanian & R. E. White, University of South Carolina, Columbia, SC, & K. S. Chen, Sandia National Laboratories, Albuquerque, NM
It was found that Zn-Ni-SiO2 composites in-crease the corrosion resistance by enhancing the kinetic limitations on hydrogen discharge reaction on deposited composite layers. The hydrogen permeation rates were evaluated as a function of: (a) alloy composition; (b) deposition parameters; and (c) concentration of inert SiO2 particles in the electrolyte. The optimum experimental conditions for the deposition of Zn-Ni-SiO2 alloy, which provides good corrosion and hydrogen permeation resistance, will be reported.
1:30 p.m.--Electroless Deposition of Copper on Polyimide Substrate: Mathematical Model Development & Experimental Validation
Professor Branko N. Popov, M. Ramasubramanian, R. E. White & K. S. Chen, University of South Carolina, Columbia, SC
The technology of electroless copper deposition on a palladium- catalyzed polymer matrix is being studied. This polymeric matrix, which has the palladium catalyst dispersed in it, promotes better adhesion between the metal coating and substrate when compared to the conventional PdCl 2 /SnCl 2 activation process. The objective of this effort is to develop a mathematical model for the electroless copper deposition on these palladium- catalyzed polyimide substrates. The solution chemistry of the electroless copper bath is studied as a function of the pH. The mathematical model takes into account (a) the solution concentration profile in the diffusion layer; (b) mixed potential theory; (c) mass transfer to the polyimide substrate-electrolyte interface; and (d) chemical reactions occurring at the substrate surface. The results obtained from the experiments carried out for electroless copper deposition under various operating conditions will be reported. The effect of experimental parameters such as pH of the electrolyte, catalytic activity of the substrate, bath temperature, and concentration ratio of the reducing agent and copper ion concentration on the rate of the metal deposition, will be discussed.
2 p.m.--A Model of Copper Electrodeposition from Cyanide Electrolyte, Part II--Current Distribution on a Disk Electrode (AESF Project #91)
David A. Dudek & Professor Peter S. Fedkiw, Department of Chemical Engineering, North Carolina University Raleigh, NC
In previous work, we developed a theoretical model of copper deposition from cyanide electrolyte on a planar electrode to provide quantitative framework for investigating the deposition mechanism. We now extend this model to the disk electrode, which has an inherently non-uniform current distribution. In this paper, we present results from the model that describes mass transport by diffusion and migration of all complexes formed by cuprous and cyanide (CuCN aq , Cu(CN)2 - , Cu(CN)3--, and Cu(CN)4--- ). The results investigate the effects of varying solution composition (pH and stoichiometric con-centrations of CuCN, NaCN, Na2CO3 ) and electrochemical constants (exchange current density, transfer coefficients) on current distribution, electrode potential, and species concentrations at the electrode surface. This work is part of a larger program that aims to find bath formulations with-out cyanide that yield current distributions of similar uniformity to that obtained in cyanide plating baths.
2:30 p.m.--Leveling Performance of Bright D-C or Pulse-Electrodeposited Coatings as a Criterion of the Property Estimation (AESF Research Project 97)
Dr. Mois Aroyo & N. Tzonev, Technical University, Department of Chemistry, Sofia, Bulgaria
In its essence, the current work is based on the thesis that those d-c or pulse plating parameters and hydrodynamic conditions at which a maximum value of leveling power is obtained can unambiguously define the regime of electrodeposition of high quality metal coatings. In order to sustain this argument, we examine the role of a number of factors for the crystallization mechanism and leveling performance of electrodeposited metal coatings: Pulse frequency, cathodic polarization, diffusion and adsorption of brightener species.
The leveling performance of nickel coatings, which have been d-c or pulse-deposited from Watts and sulfamate electrolytes containing brighteners and a hydrodynamically active agent, are given. The leveling power dependence on pulse frequency has been established under different hydrodynamical conditions of rotation and/ or vibration of the disk electrode. Theoretical modeling considerations regarding the adsorption- diffusion mechanism of leveling in low-frequency pulse plating with brightener additives are given, too. The electrochemical porosity measurements performed for these deposits have proven the existing correlation between leveling performance and coating properties.
3 p.m.--Codeposition of Copper & Tin from Sulfate Solutions Involving Surface-Active Substances
Dr. Professor Arvydas Survila, Dr. Zenius Mochus & Dr. Ona Galdikiene (now deceased), Institute of Chemistry, Vilnius, Lithuania
The sequence of partial electrochemical processes was established in solutions involving Cu (II), Sn (II), Laprol 2402-C (co-polymer of ethene and propene oxides) and other surface-active substances. While increasing the cathodic polarization, the electroreduction of copper, tin, and evaluation of hydrogen proceeds. Laprol 2402-C acts as an inhibitor because of its adsorption in the certain range of potentials where the deep minimum on voltammograms arises. The so-called "reverse peaks" are observed with reverse potential scan as a result of the variations of phase composition of the deposits with electrode potential. Adsorption phenomena are responsible for current oscillations taking part in the region where the transition from active to passive steady state is possible.
3:30 p.m.--Process Optimization & Pollution Prevention via OP2EP-Advisor
J.P. Gong, K.Q. Luo & Prof. Yinlun Huang, Wayne State University, Detroit, MI
Process optimization is a necessary step in effective pollution prevention (P2) in a plating plant. The optimization requires a comprehensive evaluation of process design and operational strategies. In the current work, a computer-aided tool, namely OP2EP-Advisor, is developed. This Windows®- based tool integrates various process models and engineers' experience, and is capable of identifying the bottleneck of waste reduction and providing valuable decisions on production optimization and P2. The practicality of the tool is demonstrated by optimizing a cleaning/rinsing system. The optimization leads to a significant reduction of chemical and water usage and an improvement of cleaning and rinsing efficiency, thereby effectively minimizing wastes.
4 p.m.--Computational Evaluation of Influence on Major Factors of Process of an Electrodeposition on Distribution of a Current in a Loading of a Drum
Illia Andreev & Ganna Megevich, Kazan State Technological University, Russia
This paper is a consideration of methods and outcomes of calculations of distribution of a current on the cathode of a mesh with mutually perpendicular electrodes.
Zinc & Cadmium Processes
June 26 (Thursday Morning)
Session Organizer & Chairman: Douglas Lay, CEF, Taskem, Inc., Cleveland, OH
8 a.m.--Elimination of Solution Growth in Chloride Zinc Solutions
Richard Painter, Pavco, Inc., Cleveland, OhioSolution growth is a perennial problem with chloride zinc electrolytes. The surfactants used in chloride zinc plating affect surface tension so that the volume of rinse water dragged into the bath is more than the volume of bath dragged out. The excess solution is typically decanted and waste-treated. The economic pressure on platers has resulted in several strategies to eliminate solution growth. This paper will look at the use of evaporators, higher solution temperatures, and inert anodes in order to abate solution growth. The cost advantages of stopping solution growth will be discussed.
8:30 a.m.--Change in Surface Color of the Chromated Film Under High Humidity Environment
Yon-Kyun Song, Hyung-Joon Kim, Pohang Iron and Steel Company, Kyungbuk, Korea
Chromate conversion coatings are widely used for enhancement of corrosion resistance. The color of the chromated film on galvanized steel sheet depends on the solution composition. One of the common colors is blue. The color of the chromated film on electrogalvanized sheet is changed from blue to black in a high humidity environment. Even though the quality of chromated films is not deteriorated by color changes, the end user complained about its appearance. In this study, to help identify the cause of the color changes from blue to black, the chemical state of the chromium and zinc were investigated by using the electrical analysis tools (SEM, SAM, XPS and XRD). A new chromating solution was developed to reduce the color change of the chromated film in a high humidity environment.
9 a.m.--The Role of Lubricant for Lubricant-Coated Steel Sheet
Chan-Sup Park & Joon-Hyung Jo, Pohang Iron and Steel Company, Pohang, Korea
Lubricating resin (mainly composed of resin co-polymer, hardener, lubricant, and colloidal silica, etc.) for zinc-coated steel sheet was developed for the application at in-line. Adding the lubricant to the resin is important to control the quality of the lubricant-coated steel sheet. Its quality was characterized with respect to kinds, melting temperature, amount and mixing ration of lubricant. Pretreatment, baking temperature and kinds of resin were also taken into account to evaluate the quality properties.
9:30 a.m.--A New Alkaline Zinc-Nickel Electrolyte
Victor G. Roev & R. A. Kaidrikov, Kazan State Technological University, Kazan, Russian Federation
For many years, electrodeposited zinc coatings have found extensive used for the corrosion protection of steel. The processes for plating from zincate electrolytes are very useful in the auto-mobile industry. On the other hand, the alkaline zinc-nickel (12-13% Ni) alloy plating is attractive in order to obtain the best quality of coatings with the best corrosion resistance. In this work, some results relating to the study of a new zinc-nickel (12-13% Ni) zincate-type electrolyte will be described. Results show that Zn-Ni alloy coatings have an almost constant thickness over intricate shapes combined with an almost constant nickel content. Research and performance data will be presented.
10 a.m.--Corrosion of Zn in Chromating Solution: The Composition Model of Diffusion Layer
Professor R. Sarmaitis, Dr. V. Dikinis, Dr. V. Rezaite Institute of Chemistry, Vilnius, Lithuania
The concentration profiles of the components of the chromating solution were calculated on the basis of mass transfer model, taking into account the dynamic chemical equilibriums. The data of the composition model of the diffusion layer alongside the analysis of the solubility of the series of Cr (III), Zn (II) and Cu (II) compounds allowed the determination of the composition of conversion coatings formed on the surface of Zn in the chromating solutions. The presented data led to the conclusion that anions of inorganic and organic acids facilitate the Zn corrosion in chromating solution as a result of the easy contact of the solution components with the surface and contributing to the reduction of Cr(IV) to Cr (III).
June 26 (Thursday Morning)
Session Organizer & Chairman: Thomas Foulds, Boeing Commercial Airplane Group, Seattle, WA
8 a.m.--Thiosulfate--An Unwelcome Member in the Aluminum Chemical Milling Bath
T. D. Brown & L. E. Bruce, McDonnell Douglas, Long Beach, CA
A major problem of the 104,400-gal type 1 aluminum chemical milling tank was surface roughness with etch rate decline. The tank, DC-05, was installed in 1988 when aerospace was entering a major retrenchment. Preliminary investigation revealed that the root cause of the problem was that DC-05 was not operating at peak capacity. Ten-thousand gallons of sulfur concentrate was added during the year which, with the initial charge, equaled 20 tons of sulfur in the bath, with short-term improvements. By 1989, analyses of the bath showed that the N 1 (caustic concentration) and N 2 (aluminum concentration) were in range, but the sulfur concentration was surprisingly low. Once again, the tank produced rough surfaces and a slow etch rate. We began to question adding more sulfur concentrate. Laboratory testing found that the best cure was to discard a portion of the bath and replace with water. The 1991 lab report, LR-15233, determined the relationship of the chemical milling bath condition and sodium thiosulfate. DC-05 was drained and refurbished in the spring of 1996 and the rate/ surface problem appeared again on etched production parts within a few months. Analyses showed excess thiosulfate present. This paper will follow the investigations, testing, findings, and solutions to returning tank DC-05 to proper operating conditions. We found that while sulfur is good for a chemical milling bath, when it converts to thiosulfate, the surface roughness will increase and the etch rate will approach zero.
8:30 a.m.--Effect of Sulfur Components on Surface Roughness from Aluminum Chemical Mill Etch Tanks
Thomas Foulds, Boeing Commercial Airplane Group, Renton, WA
In 1996 Boeing replaced a 1950s era aluminum chemical milling shop with a new one in Auburn, WA. At the original Plant 2 location, etch tanks lasted three weeks before dumping because of a low etch rate or because the tank began producing rough 7075 alloy fillets. Chem-mill etch tanks normally work this way. The larger tanks at Auburn lasted a little longer, but failed for different reasons. They had to be dumped because of end-grain pitting or a very rough surface on the flat portion of a 2024 alloy pocket. This paper relates the different failure mode to the effect of sulfur compounds (sulfite, sulfate, thiosulfate and polysulfides) formed in the etch tank from sodium sulfide. Sodium sulfide is a standard Type II etch solution ingredient.
9 a.m.--Chemical Milling Bath Caustic Recycling & Aluminum By-Product Recovery Using Diffusion Dialysis
Mark Jaffari, Malek, Inc., San Diego, CA
This paper describes the successful application of diffusion dialysis to enhance efficient caustic regeneration and high- quality aluminum by-product recovery. Advantages of this approach over traditional methods include more precise chemical milling bath control and lower energy requirements, as well as production of a more valuable aluminum by-product.
9:30 a.m.--Comparison of Chemical Maintenance Methods for Nitric/HF Milling Solutions
Dr. Thomas Hanlon, United Technologies Research Center, East Hartford, CT & Peter Johnson, Sikorsky Aircraft, Stratford, CT
Chemistry control methods for nitric/hydrofluoric milling solutions are compared. Standard methods add acids weekly, based on analyses. This necessitates periodic decanting to maintain titanium below 32 gL. Production interruptions and inherent EH&S risks of transferring large acid volumes are disadvantageous. Feed and bleed is another control method. Advantages are level maintenance of acid/metal concentrations and steady, low-volume waste flow. Third control method treats a side stream using ion exchange, partially removing metal while discarding proportionally lower acid volumes. The advertised result is constant chemistry with no process stop-pages. In practice, more frequent solution analyses/ additions and periodic decanting are required.
10 a.m.--Quality Improvement of the Chemical Milling Process
Bruce Griffin, McDonnell Douglas, St. Louis, MO
The chemical milling process is used extensively in the manufacture of aluminum, titanium, and steel components for the aerospace industry. The process is employed to reduce airframe weight by selective and controlled metal dissolution from airframe components. When chemically milled parts are assembled, however, part-to-part interference frequently occurs. This situation suggests that current standards for part quality are not sufficient.
Quality control techniques currently used in the chemical milling process are based on the concept of zero defects. Process output that falls within a specified engineering tolerance is acceptable and is shipped to the customer. Components or parts that are acceptable by the zero defects philosophy may actually require rework. As a result, the parts cause a loss to the customer. This study identified chem-mill undercut ratio as the process characteristic with the greatest effect on chem-mill part quality.
This study demonstrates application of quality engineering techniques to the chemical milling process for improvement of the quality of chemically milled parts. Quality engineering tools demonstrated include Pareto, Cause and Effect Diagrams, Taguchi/Design of Experiment Techniques, Regression Analysis of experiment data, and Tauchi Loss Function.
10:30 a.m.--Comparison of Water-based Maskants to Solvent-based Maskants with Recovery
Jim Wichman, AC Products, Placenta, CA
Traditional chemical milling maskants require significant usage of toluene, xylene and perchloroethylene, etc., for their application to aircraft fuselage skins and structural components. They must be used in conjunction with a solvent recovery system to comply with current and future air quality regulations. Water-based chemical milling maskants provide compliance to air quality regulations without the use of a solvent recovery system. This paper discusses the advantages and disadvantages for each method of compliance.