Increases solder volume by about 10-20 percent in the package you are
using. Increases likelyhood of bridging. Reduces effects of co-planarity
problems. Will not increase clearance that much.

Baking out the part was good advice. Verify temperature profile on the
component, set ramp rate at 2?C per second. Don't exceed 220?C on the
package, give the system time, stay above reflow for at least 30 seconds
(measured under the part). And watch the cooling rate, not too fast on
the way back down to 180?C.


> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Peter Lee
> Sent: Tuesday, September 10, 2002 10:35 AM
> To: [log in to unmask]
> Subject: Re: [TN] BGA rework - excessive collapsing
>
>
> What would be the impact of using mini-stencil to paste the
> board for BGA rework?
>
> Would it increase the chance of bridging or minimize it
> through increased clearance and solder volume?
>
> Rgds,
> Peter
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Earl Moon
> Sent: Monday, September 09, 2002 4:53 PM
> To: [log in to unmask]
> Subject: Re: [TN] BGA rework - excessive collapsing
>
> With respect to PCB heating, some rework stations do a pretty
> good job of preheating the board when the profile is
> carefully planned and used. With that, the board most often
> is not subject to warpage as you speak.
>
> Earl
>

>

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