The ONLY reason that I can see to change this finish is because of brittle
fracture at the interface between BGA packages and the board.

The reason for this is that an ENIG joint has approximately half of the
shear strength of an AG or HASL joint and the much higher thermal transition
temperature from solidus to room temp can set up destructive shear forces.

It has been very noticeable that a large number of BGA manufacturers have
moved away from ENIG as a finish on the component substrate over the last 2
years.

John

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dave Seymour
Sent: Monday, August 14, 2006 10:33 AM
To: [log in to unmask]
Subject: [TN] Immerison Au vs Immersion Ag

We are having a little talk about surface finish for
RoHS compliance.

We have been doing Immersion Gold for 10+ years and
are starting to switch to Immersion Silver because some feel
that Silver is a better finish for RoHS compliance.

I can't find anything that says one can not be compliant with
Immersion Gold and I'm trying to figure out why the surface finish
should change at all.

Could someone point to some articles, opinions or sources that
might help resolve the issue?

I'm out doing some web looking now.

Thanks
Dave



--
Dave Seymour, CID+
Catapult Communications Inc.
800 Perimeter Park Dr, Suite A
Morrisville, NC 27560

Direct: (919)653-4249
Main: (919)653-4180
Fax: (919)653-4297

[log in to unmask]

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