I am resending this massage to the Technet because I can not believe no one
out there wants to tackle this one.

Does anyone know of any individuals associated with IPC who would be able
to answer these questions (see below). We are experiencing Barrel Cracking
on the MC-3D material from our vendors but it seems the cracking is only
occurring after the IPC-TM-650 2.6.8 Thermal Stress, Plated Through Holes
test is done at the 550° F temp. If we lower the temperature to say 475°F
to 500°F the barrel cracks do not seem to appear after cross-sectioning.
The material survives this test when the laminate supplier tests per this
spec due to the fact that there are no holes in the material. They are only
looking for material separation (copper from substrate), measling and that
sort of things. This is not a problem with FR-4 from the same vendors. We
have requested an elongation test be preformed to check the copper for Z
axis expansion. We have some boards that were known not to have not passed
this test but because they were needed in house ASAP our purchasing
department had them shipped in now our PMI department is sitting on them
until I can get answers to the questions below.
 
Is the temperature called out in IPC-TM-650 2.6.8 specific to FR-4?

Is this test valid for Composite material such as MC-3D material from
Glassteel Industrial Laminates?
 
What is the reason for specifying 550°C temperature?
 
What kind of acceleration factors or failure rates can been expected from
this test?
 
If test is run at 475°C to 500°C and boards pass test what kind of life
expectancy can be expected Vs testing at 550°C?
 
Is this test designed to be a destructive test for composite materials?
 
Steve Collins
Antec Corporation

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