Plating Blisters, need help

Guest

Hi! Need help in our plating issue regarding blisters. Below are the details!

Blisters were monitored in some of leadtypes processed in one of our
high-speed strip-to-strip MECO plating machines. These blisters became
visible after the 8-hour Temp Cycle process (-65 to 150 degrees Celcius)
and after 2 hours bake at 170 degree Celcius. These blister-affected units
passed Solderability Test at standard preconditions of 2 hours bake at 170
degrees Celcius and 8 hours steam age with marginal pin holes using the Dip
and Look Method.

The leadtypes affected with blisters have either a base material of CDA 151
Cu or Olin Alloy 151. Our pretreatment process includes the Electrodeflash
(using MECO Deflash Chemical), Electroclean (using MECO's Surclean and NaOH
cleaners) and Descale process (using Rohm and Haas Actronal 550).

We've verified that the concentration and life of our pretreatment chemicals
including plating chemicals are within the required specifications and
tolerance. The life of our Deflash chemical is six months, our
Electroclean, one month and our Descale chemical, two weeks. We do carbon
filtration of our plating chemicals every six months.

Guest

When was the last filtration done? Have you done SEM inspection and EDX analysis on the blisters? Any sign of contam?

Dumbledore

Posted: Fri Oct 14, 2026 12:31 pm Post subject:

Thanks Dumbledore! Our plating solution is newly transferred (life is approximately three weeks after carbon filtration). We've tried to do SEM and EDX of area underneath blisters but we're not seeing any possible contaminants. We're talking here of trace contaminants I guess, and so EDX won't detect these surface contaminants even at lower voltage setting (3 - 5). We've acquired outside analysis of blister affected areas through Auger analysis and we're still waiting for the results.

I have some questions though that perhaps you could answer.
1. Do you have any experience where antioxidant and organic additives in the plating solution decomposed. What are usually the decomposition products?

2. If my base material and pretreatment processes are OK, it is highly possible that my problem is in the plating side. To which specific plating component should I consider to evaluate in lab scale to determine effects in the formation of blisters?

Thanks!

Guest

1, In plating solution, the organic additives decompose complicatedly, so it is so hard to say what is those decomposition products.

2, Based on your description, it is possible that there is something wrong with your plating solution. Firstly, you should consider the contaminant including metal and organic if you are sure that the base material and pretreatment process are okay. Maybe you should do one more carbon treatment even though you just did it before three weeks.

3, Why do only the copper 151 have the blister issue on the same plating machine? Others are all okay? What is the difference for 151 compared with other copper material? Maybe you should consider specific setup for this 151 material, including the higher concentration of cleaner and activation, the higher current density, in order to improve the attachment for deposition to base material.

Best regards
Janssen

Posted: Tue Nov 15, 2025 11:10 am Post subject:

Thank you Janssen for the inputs.

Based on our initial results, Sn was present in our pretreated samples. This could be the possible contaminant that is causing our problem. Sn could be coming from the belt (sometimes because of incomplete stripping) or from the plated dummies that we used once unplated dummies are not available. From literature though, metallic contaminants are more likely to manifest blisters right after plating. The blisters that we are seeing on our products manifest only after heat treatment suggesting the contaminants maybe more of an organic one. We are still digging as to the rootcause of the issue. Anyone who has encountered blistering with mettalic contaminants after heat treatment? Anyone who could share their blister problem and how eventually it was solved?

Regarding the use of dummy, our practice is to use before and after a run to have an even thicknes distribution. I am presently reading related literature wherein dummies are not being used and certain control is being done on plating rectifiers to avoid burning/burnt plating. The control is effective in preventing burnt plating as I see it but how can I control the plating distribution? We have strict requirement for Cpk of Plating thickness..... Anyone who has this practice. Please help.....

Janssen, I forgot to mention that we are seeing blisters also on our C 194 base materials.

Thanks and best regards,
Devil's Advocate

Posted: Sat Nov 19, 2025 4:58 pm Post subject:

Hi,

The cause of blister occured only after heat treatment, I think, is poor adhesive force between base material and plating deposite because of the poor treatment including electro clean and descale.

What is the effect if you make up new chemical in both electro clean and descale? As you know, if the grease and oxidation on copper could not be thoroughly removed, the adhesive force of deposite will be poor. Maybe you could think of another chemical for descale, that also comes from rohm and haas company. You could contact with your chemical vendor.

I am also so much interesting in the plating issue without the use of dummy. Regarding the thickness distribution, I believe there is the resolving method. Have you collected enough thickness data without dummy, that result in a poor Cpk compared with the data using dummy.
Do you think of a DOE method to improve the thickness distribution?

By the way, would you like to share your related literature about plating with me? I look forward to learning more about plating. Thanks.

Best Regards
Janssen