I believe that glass etching, as a minimum to "frost" or micro etch the
glass is needed. Sodium Bifloride and replaced some of the more
aggressive chemistries over the years, but anyone doing a good desmear
and certainly plasma needs to remove the glass left protruding. It is
only on the order of .2 mil, but given the drive to refine the cu
plating processes to support the increasing densities, the copper
thickness in the barrel will be kept to a minimum. Both desmear and
glass etch are critical to maintain a reliable copper barrel.
Jeffrey Bush
Director, Quality Assurance and Technical Support
76 Technology Drive - POB 1890
Brattleboro, Vermont 05302-1890
Tel. 802.257.4571.21 Fax. 802.257.0011
[log in to unmask]
http://www.vtcircuits.com
-----Original Message-----
From: Reeves, Tim R. [mailto:[log in to unmask]]
Sent: Wednesday, March 31, 2004 2:04 PM
To: [log in to unmask]
Subject: Re: [TN] Hole wall quality
Everyone is saying inadequate glass etch but few fabricators these days
are really using a glass etch. Drilling doesn't look good, but I'd say
it's over-aggressive desmear. That's why so much glass fiber protrusion.
Franklin, what was desmear condition? Alkaline permanganate? How long,
what temp.? One-pass or two? Is it ordinary FR-4, high Tg, or more high
performance material? The plating definitely looks thin, based on
comparison with inner foil, whether it's 1 oz. or 1/2 oz.
Tim Reeves
Tyco Printed Circuit Group - Dallas Division
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Werner Engelmaier
Sent: Tuesday, March 30, 2004 9:08 AM
Subject: Re: Hole wall quality
Hi Franklin,
Whether or not these PWBs will give trouble in service depends on the
product appllication--o.k. for benign environments, likely to fail in
servere environments. The certainly are not the prettiest x-sections I
have seen--inadequate glass etch, some glass-fiber rip-out, l plating
rather thin---all resulting in stress risers in thin plating that is
thinner still localized.
Regards,
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting 7
Jasmine Run Ormond Beach, FL 32174 USA
Phone: 386-437-8747, Fax: 386-437-8737
E-mail: [log in to unmask], Website: www.engelmaier.com
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