Further to this, I would like to enquire if for 0402 chips, tombstoning
etc... if a straight reduction in the width of the stencil can provide the
same effect as a homeplate. Presummably the homeplate reduces the effect of
the paste being squeezed out by the chip being placed on top of it, causing
solderballs and with 0402s the risk of tombstoning, the reduced solder
volume will lower the surface tension during reflow, thus avoiding pulling
the chip up on it's end. Anyway, can a narrow strip of paste, say 16 thou
(mil) give the same results?
Also, for stencil apertures, CSPs, 0.8 and 0.75mm, what are people using
generally, 14 thou(mil)... 12 thou dia??????
Regards
Edward Brunker
Sendo UK
ph:0121 766 5053
p.s. Keith are you out there???
-----Original Message-----
From: Ramsey's [mailto:[log in to unmask]]
Sent: Thursday, October 28, 1999 12:04 PM
To: [log in to unmask]
Subject: [TN] Solderball / homeplate / chip


Contract Mfg. struggles with solder balls on chip caps.
We can't control the land patterns, but we can change the stencil.
Has anyone out there tried home plate shaped openings in the stencil
even though the lands are rectangular?

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