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

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Franklin D Asbell
Sent: 23 October 2007 21:19
To: [log in to unmask]
Subject: Re: [TN] Delamination of lead free PCBs

I wrote my comments with the silly assumption that companies would apply
finishes properly. When immersion tin or silver are applied properly
they should be able to withstand the baking necessary to remove
moisture. 

This is the part where the Disclaimer goes "know your processes,
limitations, and those of your customers/suppliers".

Franklin D Asbell

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey
Sent: Tuesday, October 23, 2007 2:51 PM
To: [log in to unmask]
Subject: Re: [TN] Delamination of lead free PCBs

It should be noted that immersion tin and immersion silver may not
respond well to baking. Reckless methods can render the boards
unsolderable. 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Franklin D Asbell
Sent: Tuesday, October 23, 2007 1:39 PM
To: [log in to unmask]
Subject: Re: [TN] Delamination of lead free PCBs

Joel,

Baking was indeed required for leaded PCBs, the nature of most laminates
is to suck up moisture regardless of the Tg or final finish. Also,
depending upon the laminate type, baking may be necessary immediately
upon receipt from the board supplier. I always caution assemblers to
bake boards regardless, it just makes good sense.

Franklin D Asbell

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joel Alexander
Sent: Tuesday, October 23, 2007 11:23 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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