Regarding pores in Au-platings for cardege contacts


David

My name is Per Carlsson and working at the Swedish Institute for Production 
Engineering
Research. I have  worked with a project there we evaluated the Commercially 
available
Gold-Plated Printed Circuit Boards. In this project we analyzed porosity and 
correlate it with the
solderability. To our surprise we did not found any correlation. In your 
case you asked about
porosity on card edge contacts and  I don?t think there is any straight 
answer on this question. I
suppose that it is thicker electrodeposited gold you talk about and your 
demand on the gold is that
it should give you a good electrical contact and a good corrosion 
protection. If this is your
requirement it is really a question about the environmental load your 
equipment will experience
during service life. If the environment is corrosive, pores in the gold 
layer will lead to oxidation
of the nickel and it could result in contact failure. In this case will the 
acceptance limits be very
low. If you are interested in this matter there is a little handbook about 
corrosion of electronics
that could give you more information. "Corrosion of Electronics" Published 
by The Swedish
Corrosion Institute Bulletine 102. (Fax +46 8 16 72 70). If you are 
interested in solderability
of  Gold-Plate PWBs, we start a project about this matter in December.


Regards


Per Carlsson
IVF/EP
e-mail: [log in to unmask]


     There are plating specifications and test methods for gold over nickel
plating on printed circuit board edge connectors. Verifying plating
thickness is straight forward but what pass/fail criteria are used in the
industry for porosity of gold over nickel? How many pores per CM*CM are
allowed?
     Any sources of information/specifications would be appreciated.
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