I'm still pushing for a recommended land pattern--but the datasheet on
the part shows 0.2mm balls on a 0.5mm grid.  I think the CSP has 0.25mm
diam pads on it, so for the moment my PCB design shows 0.25mm diameter
pads also.

I know I could do microvias or down to 1mil wide trace--but wanted to
avoid the cost of going to a high technology board, at least for now.
The PCB is a low cost 2 sided board at the moment, so I set my rules to
5mil x 5mil.  I took off the unused pad, and routed the trace as far
away as possible; but the ball (if it melted properly) would be counting
on the soldermask to avoid contact.  The PCB is also low quantity, so if
I had to, I can justify higher costs (I think).

Shawn Upton, KB1CKT
Test Engineer
Allegro MicroSystems, Inc
[log in to unmask]
603.626.2429/fax: 603.641.5336

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Eric CHRISTISON
Sent: Tuesday, March 13, 2007 10:10 AM
To: [log in to unmask]
Subject: Re: [TN] Chip Scale Packagine (CSP)

Presumably the balls are too close together to get a track through to
the centre? Why don't you ask the manufacturer how you're supposed to do
it?

It might make them come up with a better layout next around (this wasn't
made by my company I hope?).

Regards,

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