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December 2007

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Subject:
From:
Genny Gibbard <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Genny Gibbard <[log in to unmask]>
Date:
Mon, 3 Dec 2007 11:13:09 -0600
Content-Type:
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How does incomplete cure delam look as compared to moisture delam?
Does one appear as prepreg separation and one appear as resin breakdown?
Which is which?

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Lee parker
Sent: December 3, 2007 11:03 AM
To: [log in to unmask]
Subject: Re: [TN] Delamination of lead free PCBs

Genny

At the AT&T PCB fab shop in Richmond (very high humidity outside,
reasonable
inside) we shipped mega millions of ImAg boards without a desiccant;
they were shrink wrapped, but this was not impervious to moisture. From
time to time we did bake the boards prior to shipping. Occasionally, the
customers found it necessary to bake the boards before assembly (without
tinfoil). 
From my experience, if the boards are free of moisture when they leave
the fab house a desiccant is not necessary. Baking prior to assembly,
may be necessary because of moisture, but it may also be caused by
incomplete curing during lamination.

Best regards

Lee

J. Lee Parker, Ph.D.
JLP Consultants LLC
804 779 3389



----- Original Message -----
From: "Genny Gibbard" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, December 03, 2007 11:01 AM
Subject: Re: [TN] Delamination of lead free PCBs


I am dragging up this 5 week old thread due to our fabricator just sent
us the Isola doc and told us we need to bake our boards.
I have two questions regarding this document in relation to Immersion
Silver.

It mentions packing with desiccant, but ImmAg docs always recommend no
desiccant, due to the potential for tarnish.  How do you resolve this?
We live on the frigid prairies, so humidity is generally WELL under 20%
at this time of year around here.  I am thinking, allow the manufacturer
to use desiccant if they package the boards with silver saver paper, and
then we remove the desiccant as soon as it arrives here, and just
repackage in MBB with a humidity card only?

Second dilemma:  The Imm Ag recommendations say to bake boards with this
finish tightly wrapped in tinfoil.  Wouldn't that inhibit the moisture
even getting out of the boards during baking?

Thanks for your time

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Franklin D Asbell
Sent: October 24, 2007 11:53 AM
To: [log in to unmask]
Subject: Re: [TN] Delamination of lead free PCBs

The information in that document contains very best practices that the
better board shops have been applying for years...I don't get how this
is being viewed and/or received as "new methods or requirements" for
board shops and assemblers???


I've read the Isola document, it does not contain anything new, it just
looks like someone (industry leader et al) finally wrote down what many
shops have been doing, and all shops should be doing...

I'm curious Ian, are you getting a stipend for pushing Isolas article?
(this was just a joke)

Franklin D Asbell

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ian Hanna
Sent: Wednesday, October 24, 2007 8:13 AM
To: [log in to unmask]
Subject: Re: [TN] Delamination of lead free PCBs

The Isola document referenced by Cheryl Tulkoff a few posts ago --
09-12-07 is a clue

<http://www.isola-group.com/images/file/TechnicalBulletinleadfreeprocedu
res091207.pdf>

I've heard talk of this from other laminate vendors but Isola has been
the first to bring this formally to the fabricators attention.

Ian


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joel Alexander
Sent: Wednesday, October 24, 2007 8:54 AM
To: [log in to unmask]
Subject: Re: [TN] Delamination of lead free PCBs


Can you provide the document names that were published in August



Joel Alexander
Quality Assurance Manager
TT APSCO, INC.




Ian Hanna <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
10/24/2007 08:47 AM

Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to Ian Hanna
<[log in to unmask]>


To
[log in to unmask]
cc

Subject
Re: [TN] Delamination of lead free PCBs


These specific guidelines for lead-free were first published in august
of this year  -- this guidance is a departure from that given for modern
laminates, from roughly 1990 on up...

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]
Sent: Wednesday, October 24, 2007 6:26 AM
To: [log in to unmask]
Subject: Re: [TN] Delamination of lead free PCBs


(chuckle) A recent requirement!!!

If your board supplier told you baking to remove moisture is a 'recent
requirement' then they are either very unknowledgeable about their
laminates or just plain deceiving you.

In either respect, good luck on being reimbursed.

Franklin D Asbell

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]
Sent: Wednesday, October 24, 2007 2:46 AM
To: [log in to unmask]
Subject: Re: [TN] Delamination of lead free PCBs

We just had a similar thing happen, with FR4 HR370.  Before we did'nt
bake prior to assembly as the boards came direct from the board house,
now we are seeing de-lam.  They told us that it is a recent requirement
that came from the material supplier that they forgot to inform us of.
Ours are 12 layer, stacked vias.  Currently we trying to get some money
back!

Ian Thomas

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