Paul
In the application I am familiar with the copper thickness of the barrels was a nominal of one mil. Even after cycling the pins in and out of the barrels we did not break through the copper. We did 40 year life testing and found press fit pins in bard copper was a very robust design. many of these boards have been in uncontrolled environments for 30 years and I am not aware of any issues.
Best regards
Lee
J. L. Parker Ph. D.
JLP Consultants LLC
804 779 3389
----- Original Message -----
From: Paul Edwards<mailto:[log in to unmask]>
To: [log in to unmask]<mailto:[log in to unmask]>
Sent: Monday, January 11, 2010 5:06 PM
Subject: Re: [TN] Using Pressfit connectors on an Immersion Silver PWB
Since you have used press-fit connectors with ImAg in other applications, then I can assume you are using press-fits designed for thinly plated Cu barrels...
But is mil apps since the environments are typically more extreme I would consider something other than ImAg... The Press-fit will cut through to the Cu and provide an exposed channel of Cu and Ag... This gives moisture a way to penetrate not only the barrel but also the solid-solid metal joint interface from the weakest plane, the sliding plane...Mechanical movement then will leverage this plane generating micro-cracks then micro-voids which in the presence of moisture and current would cause corrosion... This will lead to joint failure, or at worst case, an intermittent failure...
I would stick with solder first then Ag-Ni...
Paul
Paul Edwards
Surface Art Engineering
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Monday, January 11, 2010 1:11 PM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: [TN] Using Pressfit connectors on an Immersion Silver PWB
Has anyone experienced any issues with using pressfit connectors on a
circuit board that has Immersion silver finish? Do I need to worry about
any tarnishing inside the pressfit connector holes? Since there will be
no solder, the holes will remain open, and thus I was wondering if there
have been any issues with this.
I am considering using immersion silver as a finish for a high
reliability design, and I have never had issues using it with thousands
of medical and military and other applications, including
telecommunication blades where pressfit connectors were used. However,
this is a military application, and I want to know if there are any
potential issues before I commit to using it for this application.
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