Sure,Werner, with black payment?
/Inge


----- Original Message ----- 
From: "Werner Engelmaier" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, November 16, 2009 5:04 PM
Subject: Re: [TN] Microvia reliability vs Lead free


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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