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Photoresist and plating

 

We are setting up a small workshop for fabricating printed circuits boards using the pattern plating process. One of the problems we have come across is photoresist residues remaining after the developing stage. This residue on the copper is invisible and prohibits electroplating. Over developing will help remove the residue but this causes problems with photoresist jagged edges and lifting. Etching on the other hand is only slightly effected as the residue breaks down during the first minute or so and then continues to etch normally. Therefore the only way we could successfully plate is after etching the copper surface to remove all traces of residue.

I'd be interested knowing whats involved with pre plate cleaning for selective plating with photoresist and if microetch is an essential part of this ?

Adam Seychell
- Melbourne, Australia

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The typical pattern plating line for pcb's is:

acid cleaner
rinses
microetch
rinses
10% sulfuric acid dip
pattern plate

The microetch step usually used is very mild (5 microinches) unless a flash plate is used after electroless.

James Totter, CEF
- Tallahassee, Florida

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Adam,

In my opinion the easiest way to solve your problem is to contact the manufacturer or seller of your resist to give you support. There are several solution you can dip in before plating to remove the residue on the copper and your manufacturer should know the ones which work best.

Regards,

Marcus Hahn
- Sachseln, Switzerland