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Determining pH and Orthophosphite level in Electroless Nickel Plating Process
We deal with Electroless Nickel plating of large parts.We use pH papers for finding pH level in the solution.The pH papers are not reliable and subjective.I would like to know if there is any other methods or instruments that we can use for it.I would also like to know about orthophosphite analysis procedure.It would be great if anyone could provide a useful input.
Thanks
Engineer - Mansfield, Texas
2004
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We've worked for over 10 years using pH papers on the floor w/o problems (0.2-0.3 pH unit increment is what we use). Electrodes are OK in the lab, but too delicate, slow and sometimes misleading for production people. Now, about the ortho question please see letter 27316 and make your choice which one you ask. Guillermo MarrufoMonterrey, NL, Mexico Some pH papers are better than others and most experienced EN applicators know two brand names that really work. We cannot give the brand names here. Your EN supplier should give you the titration procedure for Ortho and Hypo. It is too long to list here. If your supplier will not get it for you come back and I will copy the procedure and slow mail it to you.  Robert H Probert Robert H Probert Technical Services  Garner, North Carolina  With most EN baths, pH is measured using colorimetric indicating papers. However, if this is not adequate, electrometric measurements using pH meters can be used. A quality pH meter will provide a result about 0.2 pH units higher than most papers, but will be more accurate. The meter should be calibrated with two buffers over the expected pH range. A cooled bath sample should be used for the test. Most pH probes are not accurate or last long at temperatures over 180° F. Unless the samples are always cooled to the same low temperature, the meter should include a temperature compensation probe. Temperature can have a significant effect on apparent pH. Also, a fast-flow reference electrode works best for older electroless nickel baths.  Ron Duncan [deceased] - LaVergne, Tennessee It is our sad duty to note Ron's passing on Dec. 15, 2006. A brief obituary opens Episode 13 of our Podcast. |
We currently plate PC/ABS and ABS with an electroless nickel bath. We have recently increased production by about 30%. Since this time we have not been able to obtain steady pH readings of the electroless bath. The bath normally operates at 9-9.2 pH. We have used 3 different pH meters with 3 different probes. The pH did check at a normal level when we started using a particular probe/meter and additions were made in a timely manner through the use of a feeder pump. The more checks done on a meter the lower it reads, even with constant calibration. The bath would normally consume 15 gallons of ammonia
[on
eBay or
Amazon] per 24 hours of run time. Has anyone else seen this issue? Is this simply a sign of bath degradation that will necessitate dumping this bath and formulating a new one?
Any help would be greatly appreciated.
employee - Michigan
April 27, 2011
Heat in an EN solution can cause loss of ammonia. Try using pH paper strips. They are likely be more accurate in ammonium environments. Use pH papers designed for the electroplating industry. Most chemical suppliers supply pH papers. Designate the pH range you need.
Don Baudrand
Consultant - Poulsbo, Washington
(Don is co-author of "Plating on Plastics" [on Amazon or AbeBooks affil links]
and "Plating ABS Plastics" [on Amazon or eBay or AbeBooks affil links])
May 27, 2011
High temp of an EN bath is very hard on any pH probe. Use a narrow range pH paper as Don suggested. A clue, use a quick dip and read it as quick as you can- Like 5-10 seconds as the chemicals attack the color indicating materials in the paper.
James Watts- Navarre, Florida
June 1, 2011
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