Nee hao Hechong,
BGAs with heatsinks have been shown to warp and thus loading the SJs in tension.

Werner


 


 

-----Original Message-----
From: Cong He <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, 4 Dec 2008 10:08 pm
Subject:  [TN] 答复: Re: [TN] BGA soldering open issue










surface finish is hasl. 

after analysed parts of the board, we found some balls of the bga rupture.
Could it be the material of the ball(BGA) cause the problem?

by the way, there is a heatsink which is double size lager than the chip 
stick on it without other fixture.
will the heatsink be the reason?






Hechong





"Wenger, George M." <[log in to unmask]> 
发件人:  TechNet <[log in to unmask]>
2008-12-05 10:57
请答复 给
TechNet E-Mail Forum <[log in to unmask]>; 请答复 给
"Wenger, George M." <[log in to unmask]>


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主题
Re: [TN] BGA soldering open issue






What is the surface finish on your PCBA?



Necong,

What is the surface finish on your PCBA?

Regards,
George
George M. Wenger
Andrew Wireless Solutions
Senior Principal FMA / Reliability Engineer
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 [Office]  (732) 309-8964 [Cell]
[log in to unmask]
 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Cong He
Sent: Thursday, December 04, 2008 9:09 PM
To: [log in to unmask]
Subject: [TN] BGA soldering ope
n issue

dear all:

I am facing a problem of bga soldering.

when the board have just soldered ,it pass all test.
But after sometime, maybe for a few weeks,
some of the bga balls opened. the function became normal if i press the 
chip on the top side.

It seems that the pcb didn't warp much,it seems even no warp at all.
Does any of you know why? And how to improve? 






Hechong

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