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September 1998

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Subject:
From:
Jim Marsico 516-595-5879 <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 29 Sep 1998 08:00:00 -0400
Content-Type:
TEXT/PLAIN
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TEXT/PLAIN (41 lines)
Are these "dimpled" BGAs?  Are the component pads recessed below the bottom
surface?  If so, perhaps you might try screening the flux instead of
dispensing.  This might give you a better flux deposit without voids.

Jim Marsico
AIL Systems Inc.
(516) 595-5879
[log in to unmask]



Fumiaki Shigeoka wrote:

My problem is dropping solder ball from BGA devices after ball attachment
process.
First, I suspected the temperature of reflow oven, but that was sufficient to
melt
solder ball. After reflow, some balls(5-10% of strip) are missing, and empty
pads
are not wetting or partially wetting.
I found voids in flux on pad before placing ball, so I guess the void will
expand
in reflow furnace, and ball doesn't touch to pad. I use dispensing system to
provide
flux, which sometimes contaminates air void to flux on pad.
Does anyone have any experiences and suggestions to solve this problem ?

Thanks in advance.

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