Hi Carl,
If you look in IPC-7525, you will find some guidelines to reduce
solder-balling.
Look in 3.2.2 and beyond (3.2.2.5). My personal preference is modifying the
necessary apertures to oblongs. It is the simplest solution from a data
processing point of view because an oblong is a standard Gerber shape.
Besides, some tests have shown better paste release so the results become
more uniform.

Have fun,
Ahne Oosterhof
503-641-9428


-----Original Message-----
From:   TechNet [mailto:[log in to unmask]] On Behalf Of Carlr Ray
Sent:   Thursday, January 16, 2003 11:41
To:     [log in to unmask]
Subject:        [TN] Stencil Aperture Mod

How many of you guys still run product with 1:1 apertures? How many
commonly use reduced or modified apertures?

I have an issue where I can not convince some other Engineers that
modifying the apertures to correct for solder balling is a good
solution.

The process is a no clean process and the profile meets the solder
paste manufactures recommended parameters.

The solder ball appear on next to the middle of the parts (like solder
escapement) and some are trapped by the flux others or not.

Do you guys know of any standards that address these issues?

Carl Ray
Sr. Manufacturing Engineer
Huntsville, AL 35807
Phone: 256-882-4800 ext. 8845
Cell: 256-990-1990

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