Sira,

If your spec demands that you do not have solder balls, and you do ask how
to remove them - try cleaning after soldering!

I do not want to appear flippant, but if you are running no-clean with inert
gas, then the propensity of solder balls generally increases. If the product
is safety critical - clean it, it is usually cheaper and quicker.

We have many customers who profess to run no-clean but who have many
cleaners - to clean stencils, misprints and pallets and because they use a
no clean flux/wire/paste, the cleaning bill is higher.

Just some thoughts for consideration...

Regards, Graham Naisbitt

[log in to unmask]

Concoat Limited
Alasan House, Albany Park      Phone +44 (0) 1276 691100
CAMBERLEY GU15 2PL UK     Fax       +44 (0) 1276 691227
-----Original Message-----
From: Sira Rikulsurakan <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: 14 October 1998 22:01
Subject: [TN] No-Clean Solder Ball.


>Dear Technetter.
>        We are facing Solder Ball problem for SMT No-Clean process. The
>balls are always in contact with 0603 Chip capacitor and resistor and also
>fixed by flux. Diameter of the balls is less than 5 mils.
>        Stencil thick is 6 mils. Stencil apertures of the 0603 component
are
>“ Home plate “ shapes. Solder paste thickness is about 7.4 mils.
>        We had extended “Preheat” portion of reflow profile to cure solder
>paste and reduce peak temperature of “Reflow” portion to stop splash but
>solder balls are still found after reflow.
>        Would anybody please suggest us how to eliminate the solder balls.
>Thank you.
>Mark.
>
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