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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