It depends....(sorry, Doug, can't help it)
I have seen many delamination issues with standard FR4-4 and other
laminate grades outside of GD when attempts were made to use them for
high-temp solder applications. Some pwb pre-pregs have different
material classifications that may hold up to the higher temps. Others
will not, as the higher (~250C) temps will cause that particular board
design to approach its Tg, or even its Td, while it is attempting to go
through the process window where all of the components are soldered
satisfactorily, whereas the same substrate material will hold up just
fine as part of a different circuit board design. It depends on a lot of
different factors, the weight of the copper required, the overall size
of the pwb, the number of layers, the number of components and the type
of the components, and most basically, the amount of time required
within the reflow tunnel. I am sure there are a few dozen other factors.
There are some pwb materials that are designed just for these higher
temperatures, but you cannot simply swap them out with the same design
and component set and assume they will work, as they may have different
dielectric constants and other properties.
For many applications, you may have to first choose a material that best
fits your particular design and service environment, etc., and then go
through a complete requalification of the product, both from a
funtionality standpoint and from a process standpoint.
For any new pwb, I strongly recommend you run it through the reflow
process first and give it a good inspection as a minimum, before you
jump in and populate dozens of boards and reflow them only to find that
the pwb cannot withstand the lowest reflow temperature required to
obtain a good solder joint across the board. Check with your local
friendly pwb house, they can help you with appropriate material
selection, and most are very appreciative of a customer who takes the
time to get their input.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of James TerVeen
Sent: Wednesday, November 02, 2005 1:14 PM
To: [log in to unmask]
Subject: [TN] board material for high temp
What does everyone us for board material for High temperature solder
applications. We have a new product that will require the use of high
temperature solder. Will the use of conventional FR4 be sufficient.
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