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June 2006

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Subject:
From:
"Tempea, Ioan" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Tempea, Ioan
Date:
Thu, 29 Jun 2006 10:02:36 -0400
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text/plain (59 lines)
Poh,

I can see 2 reasons:
you are not heating enough. Are you measuring the temperature under the BGA? You need to peak at about 240C. Of course, if your PCB is not capable, it might get damaged.
you are not using the right tacky flux. You need lead-free capable flux, the SnPb one will decompose at these high temps.

Regards,

Ioan

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Poh Kong Hui
Sent: Thursday, June 29, 2006 9:55 AM
To: [log in to unmask]
Subject: Re: [TN] LEADFREE BGA - electrical continuity issue


Hi Technetter,

I recently faced issues with BGA of leadfree.
In the past, when we rework BGA (tine-lead), we sometime make short cut by
simply applying some paste flux, mount the BGA and reflow, it works
perfectly well on the electrical continuity.

Somehow, it seems using the same method does not work well on leadfree BGA.
Sometime, there is no issue with the electrical continuity, and sometime
there is problem with it.

We also do sometime apply (tin-lead) paste on the BGA pads, but it has the
same symptom.

We do X-ray, but not able to determine much from the X-ray picture.

Can someone advise me what had happened & how to solve such problem.

Thanks in advance.

KH Poh

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