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October 2007

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Subject:
From:
"Whittaker, Dewey (EHCOE)" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Whittaker, Dewey (EHCOE)
Date:
Mon, 29 Oct 2007 10:26:08 -0700
Content-Type:
text/plain
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text/plain (127 lines)
To bake or not to bake? Agh, that's the question, whether it's nobler in
the mind's eye to bake and suffer the slings and arrows of solderability
uncertainties or oxidental poisonings; or not to bake and go gently to
that thermal excursion and watery grave of moisture ingression.

 

The old dicy cured FR4s lulled too many people to idyllic complacencies.
The times are changing and the newer engineered laminates demand proper
attention to detail. Proper handling and storage conditions are
mandatory. Baking protocols will need to consider some of the following:

*         Laminate type

*         Cure system

*         Tg of the laminate

*         Design robustness

*         PB layer count and thickness

*         Final surface finish

*         Processing window

*         Processing profile(including ramp rate, max. temp., and TAL)

*         Compensating factors

 

Laminates that are destined for High-rel, Lead-free applications will
probably require baking. To paraphrase;

If in doubt

Bake it out

If not

Lose the lot

 

Dewey

 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joel Alexander
Sent: Tuesday, October 23, 2007 9:23 AM
To: [log in to unmask]
Subject: [TN] Delamination of lead free PCBs

 

Has anyone experienced an increase of delamination when processing in a 

lead free environment. Typically 4 to 6 layer pcbs during SMT reflow. We


are using the high temp laminate suggested for our process. When we 

contacted the supplier and they indicated that any PCBs that are over
six 

months old should be baked prior to processing. This was never required 

with leaded PCBs. 

 

Is anyone seeing the same condition and similar feedback from your PCB 

suppliers

 

 

 

Joel Alexander

Quality Assurance Manager

TT APSCO, INC. 

 

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