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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