The paper just needs to be sulfur free with an antioxidant layer apply
to one or both sides.
Jeffrey Bush
Director, Quality Assurance and Technical Support
VERMONT CIRCUITS INCORPORATED
76 Technology Drive - POB 1890
Brattleboro, Vermont 05302
Voice - 802.257.4571 ext 21
Fax - 802.257.0011
<http://www.vtcircuits.com/>
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Genny Gibbard
Sent: Thursday, June 01, 2006 2:46 PM
To: [log in to unmask]
Subject: Re: [TN] Packaging requirements for IAg Finished PWBs
I'm not trying to get advertisements, etc, here, but I've spent the last
30-45 minutes searching the internet and trying to figure out what to
search on to find all this special packaging material.
Where do you buy this stuff, and what is it called?
I think I've determined that "silver saver" is actually a brand name,
but there have to be other sources or a more generic name, right?
Where do you get just the straight neutral pH paper?
And what about boxes and bags?
Thanks,
G.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Franklin D Asbell
Sent: June 1, 2006 9:53 AM
To: [log in to unmask]
Subject: Re: [TN] Packaging requirements for IAg Finished PWBs
The same method may be used for immersion tin, I would add a desiccant
package to those.
Silver saver paper has a coating of zinc oxide and in my opinion a waste
of money.
The purpose of wrapping these into paper are 1) prevent rub or abrasion
marks, and prevent exposure to atmosphere. Zinc oxide does this but cost
probably 5 times as much as neutral pH tissue paper. The silver finish
begins to tarnish when exposed to chlorides (high pH) or sulfides (low
pH) either by direct contact or atmospheric exposure. The neutral pH
prevents such exposure without ridiculous cost.
Packaging in smaller bundles is good for the assembler as well, it
allows more flexibility during processing, ensuring large quantities of
product are not opened to the atmosphere until they are actually needed.
Franklin
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Genny Gibbard
Sent: Thursday, June 01, 2006 10:20 AM
To: [log in to unmask]
Subject: Re: [TN] Packaging requirements for IAg Finished PWBs
This is very timely. We have just been realizing that we have no formal
handling procedures in place for the newer finishes, either. We have
used the robust HASL finish for so long, I don't think people realize
how different these PCB's can be.
Can you tell me if you have any guidelines for Immersion white Sn
finish, as well? Or is the information below applicable to that as
well? We had a board supplier tell us that ImmSn needs silver saver
paper as well.
The idea of getting them packaged in small quant's from the manufacturer
is a great idea, as well.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Franklin D Asbell
Sent: June 1, 2006 9:00 AM
To: [log in to unmask]
Subject: Re: [TN] Packaging requirements for IAg Finished PWBs
Yes, we use a neutral pH paper, almost like tissue paper and fold 10 bds
max into bundles, then package these in neutral pH plastic bags.
Scratches are not so much this issue, it's more of abrasion prevention
as well as protection from the environment. We have customer's however
that once the product is received they completely remove the product
from the packaging and place them open in bins until use.
As a practice we pass along assembly and handling guidelines to all
customers who request silver finish for the first time, and with new
customers order silver finish product.
Silver finish reacts to atmosphere more dramatic than tin-lead, the
tin-lead finish is also more durable and less affected by handling,
contaminates, etc so more controlled measures must be taken with silver
finish.
Also, it is best to perform the silver finish process as close to the
end of the fabrication process as possible. We typically perform this
process after rout and final inspection. Silver finish is applied, tape
testing and visual inspection is performed and the product is
immediately packaged.
The following is an excerpt from such a procedure.
==============
5.0 Handling, packaging, and storage
5.1 It is recommended that gloves be used for all handling after the
immersion silver process.
5.2 Salts and acids from fingerprints may tarnish the silver finish.
5.3 Surfactants and/or acid cleaners should not be used on silver
finish
boards. Clean only with DI water rinses.
5.4 Silver plated boards should be packaged as soon as possible to
avoid
exposure to sulfides and chlorides in the air.
5.5 Bundle wrap silver parts in clean acid/sulfur free paper.
Neutral pH
paper is sufficient.
5.6 Storage should be in sealed neutral pH plastic bags to eliminate
direct contact with the air.
5.7 Do not allow sulfur bearing plastic to contact the silver
finish.
5.8 Do not use desiccant in the packages with silver plated boards.
5.9 Do not use rubber bands on boards. Most rubber bands contain
Sulfur
compounds.
==============
Franklin
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gary Camac
Sent: Thursday, June 01, 2006 9:47 AM
To: [log in to unmask]
Subject: [TN] Packaging requirements for IAg Finished PWBs
Good morning all,
I am struggling through a rewrite of our material specification for
PWBs. I have seen the recommendation that cover sheets and interleaf
sheets should be used to prevent scratches on IAg finished PWBs. Have
those that are using IAg seen this as necessary? We eliminated this
requirement on Sn/Pb finished PWBs some time ago without any negative
effects.
Thanks,
Gary Camac
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