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Subject:	Re: CGA attachment on BGA pattern
From:	[log in to unmask]
Reply To:	TechNet E-Mail Forum.
Date:	Wed, 3 Nov 1999 10:18:04 -0500
Content-Type:	text/plain
Parts/Attachments:	text/plain (63 lines)

Date:    Tue, 2 Nov 1999 19:17:59 -0500
From:    jong s kadesch <[log in to unmask]>
Subject: CGA attachment on BGA pattern

Dear TechNetters,

I have a substrate with BGA pattern where BGA is fanned out for vias.
Dimensions are following:

Diameter of the ball: 30 mil
Pitch: 50 mil
via drill size: 6 mil
via with annular ring: 10 mil

The substrate is solder masked for CGA attachment but exposing all the vias
(no solder mask on vias) and of course, BGA pattern.  CGA attachment cannot
be done because one BGA pad is too close to the via fanned out from another
BGA pad (average distance between two is 5 mil) which will cause short in
the event of solder bridge between the BGA pad and the via during eutectic
solder reflow process.

Is there any way that i can fix this problem without sending these
substrates back to manufacturer for remasking?
Thanks in advance.

Jong Kadesch
***************************************

Jong,

You might try "reballing" the devices using "hi-temp" spheres (Sn90 Pb10) utilizing eutectic
solder paste underprinted by 20%. This will minimize the probability of encroaching liquidus
material during reflow. If you have interest in persuing this process on a "test" basis, please
feel free to contact me directly.

Regards,

Ed Popielarski

QTA Machine
10 McLaren, Ste. D
Irvine, Ca. 92618

949-581-6601 Ph
949-581-2448 Fx
http://www.qta.net
Ask about our BGA Reballing system!

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