Hello Guenter,
    This may not be your problem but I used to work for a company where we
experienced the very same thing.  Hopefully you don't have the same problem
though.  Our problem wasn't the soldering of the BGA, we thought so and kept
beating on manufacturing.  Our problem turned out to be floating I/O pins.
There were two pins that should of had a pull-up or pull-down (an
oversight).  Anyway, the boards were intermittent until the BGA processor
was touched.  We thought it was the soldering but we were just adding some
capacitance.

Good luck,

Roger Alexander

----- Original Message -----
From: "Guenter Grossmann" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, April 07, 2004 5:05 AM
Subject: [TN] Antw: [TN] BGA soldering issue


> SenJoon
>
> 2 Reasons are possible for this kind of failure
> 1) Popcorning: Delamination of the molding from the chip ripping off
> the bonds
> 2) bad soldering
>
> Solutions:
> 1) Dry all BGAs before soldering, keep temperature as low as possible,
> control heat up rate.
> 2) Difficult to say, need first to find out why the beggars don't
> solder.
>
> --> Reason 1 is quite common.
>
> Best regards
>
> Guenter
>
>
>
>
> EMPA
> Swiss Federal Laboratories  for Materials Testing and Research
> Centre for Reliability
> Guenter Grossmann,  Senior Engineer
>
> 8600 Duebendorf
> Switzerland
>
> Phone: xx41 1 823 4279
> Fax :     xx41 1 823 4054
> mail:     [log in to unmask]
>
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