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Date: | Mon, 16 Nov 2009 11:04:32 -0500 |
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Hi Inge,
Certainly have. This is not new, and it is not very surprising.
You may be interested in my White Paper on how to design PCBs for reiability given Pb'free soldering.
Werner
-----Original Message-----
From: Hernefjord Ingemar <[log in to unmask]>
To: [log in to unmask]
Sent: Mon, Nov 16, 2009 3:22 pm
Subject: Re: [TN] Microvia reliability vs Lead free
any relationships are described, one of which is a Curtiss-Wright report. They
ave exposed identical boards to SnPb soldering/repair and compared with same
or SACs, and found a significant difference in time to failure.
1st thermal cycle to failure
As Received 6 x 230 Celcius 6 x 260
elcius
Mean 788 443 4
That is a dramatic change in via failures. We have seen some failures recently
n ordinary double sided FR-4 boards, which were exposed to several heat
xposures in conjunction with electrical testing. Far from 260 Celcius, think
nly 125 Celcius. If we got microvia issues with only 125 C, what if we use 260
(e.g. repeated repair)?
Has anyone seen any signs of via failure due to increased heat exposure in
ractice?
nge
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