Summary for nickel-boron plating pitting problem Discussion
Nickel-boron plating pitting problem is the issue Kim raises for an acid Ni-B electroplating line used on MEMS probe cards. He reports circular pits that appear on some lots but not others, even after remaking the bath, while pH, boron content, temperature, and current density are within spec. Kim also notes that adding the Ni-B wetting/leveling additive reduces, but does not eliminate, the defect, and asks whether Hull-cell testing, surface-tension checks, CVS, lower current density, or pulse/pulse-reverse plating might help. The excerpt provided does not include any replies or final diagnosis, so no answerer-specific guidance is available from the source. The main takeaway from the question itself is that the problem seems intermittent and may be tied to wetting or current-distribution effects rather than a simple bulk bath chemistry failure.
Q. Hello I am Kim.
I am currently working as a plating engineer in a manufacturer of probe cards based on MEMS (micro electro-mechanical systems) manufacturing technology.
I’m looking for guidance on an intermittent pitting defect that has appeared in our acid nickel-boron (Ni-B) electroplating line.
• Process parameters
– Bath pH : 3.9 (spec 3.9-4.1)
– Temperature: 45-50 °C
– Current density : 2.0 ASD (0.50 A)
• Defect description
– Circular pits across the surface (see photos).
– Defect appears on some lots, not all.
– A completely new bath showed the same issue <2 months after make-up.
• Troubleshooting done so far
1. Re-made the bath – pits returned.
2. pH, boron content, and temperature within spec.
3. Adding the Ni-B wetting/leveling additive reduces, but does not eliminate, the defect.
• Questions
1. Which additional checks would you recommend (Hull-cell, surface-tension, CVS, etc.)?
2. Could marginal wetting-agent depletion, combined with current crowding, explain the lot-to-lot behaviour?
3. Would lowering the current density or using pulse/pulse-reverse plating be an effective fix?
Any insights or similar experiences would be greatly appreciated.
Thank you in advance!
Kim
Bomin Kim
– Korea
July 30, 2025