Tom,
In my admittedly limited experience using SRT equipment, flexing of the BGA
seems to be almost entirely the result of too much heat on the top side
combined with inadequate or too short preheat. First place I'd look would be
at your profile.

Rick Thompson


> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Thomas C Han
> Sent: Tuesday, October 20, 1998 4:48 PM
> To: [log in to unmask]
> Subject: [TN] BGA Assembly
>
>
> I had a lot of 15 boards that I mounted PBGA388 (35mmX35mm), using
> Conceptronic BGA rework station.  As I was observing the reflow, I
> noticed  bowing of the plastic laminate on the corners of the
> component.
> Once the component was reflowed, it became level with the PCB, but the
> bowing action caused several shorts between the balls under
> the corners.
> Any suggestions on how to correct the problem?  The
> inspection following
> the reflow reveal good wetting and reflow on rest of the balls.
>
>
> Tom Han
> Ardent Systems
>
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