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Difference between tin-lead and tin-bismuth plating?
An ongoing discussion from 1996 through 2015 . . .(1996)
Q. Does anyone plate Bismuth or bismuth-tin? Can anyone give me practical advise on such plating?
I am very anxious to get the answer. This service is great!
A. Atotech supplies a tin bismuth alloy solution "Tinsol B", this is an alkaline potassium stannate based solution, particularly for use with insoluble anodes, as the tin is replenished using a liquid replenisher, the bismuth concentration is quite low. But sufficient to prevent the formation of "tin pest" in cold conditions. We've used it on oilfield couplers putting down 0.003" in 45 minutes! It's pretty expensive though (in England anyway).
- Lowestoft, U.K.
A. Schlotter Co. in Germany produce a Tin/Bismuth (5-10% Bi.) Also a Tin/Silver. Both used as a whisker free replacement for tin on components in lead-free manufacturing.Ian Walton
December 1, 2010
Q. Did anyone find a supplier for electroplating eutectic tin-bismuth?George Carson
supplier - Irvine, California USA
Q. I'm really interested in this project. As you know, Sn/Pb plating will be transferred to Sn/Bi or Sn/Ag in the Semiconductor industry. So, I also want to know where can I get any information or theory about Sn/Bi. Do you know any Book name about that? I am sorry because I can't help you.kim young chol
A. I am interested in electroplating of bismuth from aqueous solutions, so what would you like to know about it.Mohamed Ghanem
university of Southampton, chemistry department Southampton- UK
Q. Share me info about tin bismuth plating in semiconductor industry.Santanadass
There is also a growing interest in high speed pure-tin plating on lead frames that do not have "whiskers" problem. A number of companies have done intensive testing and to-date results have been encouraging.K M Tang
Q. What type of tools are being used to polish or de-flash tin-bismuth?Walter Cunial
I'm working in an electronics company. We are using Tin bismuth plating solution. I just want to know the difference between tin-lead and tin-bismuth and what special characteristic does they have (if any)?Jay Balingit
Operator - Tarlac, Philippines
A. Your question can only be answered in general terms because you do not give any details about the exact compositions of your tin-lead and tin-bismuth alloys. The first simple answer is that one contains lead and the other bismuth. Seriously, though, it has long been the desire of the electronics industry and many others, to eliminate lead from their product range (especially solders) as it is very toxic and can cause the industry's workers many long term health problems. One safe common substitute for lead is silver, but this is expensive. Another one is bismuth, which is cheaper but not so widely available. Bismuth and tin will produce usable solders and alloys, but they may well have slightly different characteristics to tin-lead; for instance, the ratio of bismuth to tin will be different to that for lead and tin for any given melting point alloy. It will also have different surface tension and viscosity characteristics. You may also see a difference in its tendency to form whiskers.
R&D practical scientist
Chesham, Bucks, UK
A. Tin Bismuth as a plating material is interesting. However, there are concerns when soldering these things with Ti- Lead solder since this forms an alloy that melts at 96 °C. I heard something that less than 3 % Bi is no problem. Does anyone have literature regarding this item? I am especially interested in platings with low Bi- content and the effect of local concentration build up leading to areas with more than 3% Bi concentration.Guenter Grossmann
EMPA - Uebendorf, Switzerland
To minimize searching and thrashing, and to provide multiple points of view, Finishing.com combined formerly separate threads into the single dialog you are now viewing. Please forgive any resultant repetition.
Alkaline Tin Bismuth Plating(2007)
Q. My question involves alkaline tin plating alloyed with 0.3 % to 3.0% bismuth. The bath is a 320 gallon potassium stannate process. Tin metal 5.3 - 10.6 oz/gal, free KOH 2 - 8 oz/gal, soluble bismuth 20 - 40 ppm, temperature 170 F, eductors for mild solution circulation, cathode bar agitation, and stainless steel anodes. I plate at 10 - 20 ASF to 0.00015 inch minimum, with 0.0006 inch minimum copper underplate. My coating composition must be IAW ASTM B545 [link by ed. to spec at TechStreet] except 0.3 to 3.0 wt.% bismuth is co-deposited with the tin. My problem is roughness. This is a new bath make up. Analytical analysis shows my tin metal at 5.8 oz/gal, free KOH at 2.5 oz/gal, and Bi at 20 ppm. The roughness looks to be dark, almost black, and is more likely to be found in HCD, and shelf areas. I'm thinking we plated at too high a current density and polarized the anodes, and started producing stannic tin. I can see a few very small black specs circulating in the solution. The deposit looks good with the exception of the roughness, and Bi in the deposit is approximately 1.0 %. I've added about 1.5 gallons H202 to oxidize the tin. I did this at 120 F (temperature too high ?). Am I on the right track here, or should I be looking elsewhere? Parts look good out of the copper. Thanks for any and all replies.Stewart Holloway
Sr. Materials & Process Eng. - Cedar Rapids, Iowa, USA
January 24, 2012
Q. I am interested to know the method of analyzing the solution of Sn-Bi plating Bath. I am particular about finding out content of Bismuth Nitrate (less than 0.5 g/l) in the solution. Expecting to get answer from plating experts I am posting my question in this forum. Thank you.Amit k Singh
- Hyderabad, AP, India
October 11, 2012
Q. Bismuth tin plating on aluminum -- Why am I getting blisters after the parts are baked? I have flushed the blind holes very good while prepping my parts and still I end up with blisters.Caleb Shiltz
- Coon Rapids, Minnesota, USA
A. What is your process? No one can tell you what is going wrong if we don't know what you are doing!
R&D practical scientist
Chesham, Bucks, UK
October 22, 2012
A. You may have a problem with stannite tin in the bath causing the dark deposits. Your anode current density may be too low causing tin to dissolve as stannite instead of stannate. The anodes should have a yellowish film when in operation.
Small blisters on aluminum after baking are very common. You should first determine whether the tin is blistering over a sound copper deposit (unlikely) or if the blister is between the copper and the aluminum. Also, you should enter the tin bath with current on.
consultant - Cleveland, Ohio
April 4, 2015 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
I want to know the process details and manufacturer (metal finisher) for tin/bismuth plating since we have a requirement for tin/bismuth plating. Base metal is steel.
- chennai, india
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