I would hope your using an underfill material to prevent the shear stresses when a large heat sink is used.
-------------- Original message --------------
From: Cong He <[log in to unmask]>
> 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."
> 发件人: TechNet
> 2008-12-05 10:57
> 请答复 给
> TechNet E-Mail Forum ; 请答复 给
> "Wenger, George M."
>
>
> 收件人
> [log in to unmask]
> 抄送
>
> 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 open 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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