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Au Plating with Dry Film

2007

Hi All,

Currently I am encountering this problem:

My product requires me to do Pattern Au Plating first , followed by Ni Pattern Plating.
Both the Au & Ni share the same pattern.
However, the headache problem is that the Dry Film doesn't really hold after Au Plating.
Sometimes, it will peel off from the board; while sometimes, it will have seepage.

May I request any good suggestion to make this dry film stand as it is from the beginning till end of the process?

Eve Wong
Product Engineer - Singapore

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First of two simultaneous responses --

Eve
Probably the most important things to control for good adhesion are pre-cleaning the substrate and correct exposure of the resist.
Exposure is very important. If you are using a negative resist, it is common to cross link the polymer sufficiently to get what looks like a good image but it is not strong enough to stand plating conditions. If you do not have a method of control, ask your resist supplier about an exposure step wedge.

Geoff Smith
Hampshire, England
2007

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Second of two simultaneous responses --

Try flood exposing the boards after developing the patterns and prior to your plating process. This works with many negative photosensitive resists in increasing their durability during subsequent processing.

Kevin Dowhower
- Lompoc, California, USA
2007