First, beware specifying laminate material for lead free soldering by Tg.
You can spec a 170 Tg material with an epoxy that breaks down at soldering
temperatures, reducing it's Tg to about 130 after a single reflow
operation.  Or you can spec a 140 Tg that maintains it's properties over
multiple passes.  Most reflow profiles are not long enough to cause the Tg
to be significant.  Far more important are the CTE, Td, CAF, non-dicy
curing.....

When this first became an issue, many companies went right to the Isola-410
and comparable materials.  These are 170Tg, but also have higher Td, lower
CTE, are non-dicy, and less susceptible to Cathode-Anode failures.  As a
response to RoHS demand, some suppliers are now marketing a product with
similar properties, but a Tg around 130.  For a normal single heating
operation, they claim these work, and they are a bit cheaper.

We have seen inconsistent price increases, but it's between 10-30%, partly
because we were somewhat underspecified in the past, allowing fabricators
to shop around a bit.

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