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Subject:
From:
Werner Engelmaier <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Werner Engelmaier <[log in to unmask]>
Date:
Tue, 17 Nov 2009 10:58:28 -0500
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text/plain (171 lines)
 Hi Inge,
Bucks are green.
But you should know, nothing good is for nothing. 
I take it, you work pro bono for Saab ;-)
Werner

 

 

-----Original Message-----
From: Inge <[log in to unmask]>
To: TechNet E-Mail Forum <[log in to unmask]>; Werner Engelmaier <[log in to unmask]>
Sent: Mon, Nov 16, 2009 11:14 pm
Subject: Re: [TN] Microvia reliability vs Lead free









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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