It seems all I am able to get on this one is opinions no scientific inf.
What I'm looking for is what will be the mean time to failure if a board is
not tested at the 550° temp. I am not challenging the need for the test or
the temperatures associated with it.

More background inf. It does not seem to matter how much copper is in the
hole, we have seen cracking with .00062 to .0017 copper thickness. I am
pretty sure that the problem here is that the MC-3D Z axis expansion is
greater than the copper being plated. The Z-Axis Expansion Coefficient
RT-Tg = 100ppm/°C and the Z-Axis Expansion Coefficiant Tg-260°C =
360ppm/°C. What I'm unsure of is what is the CTE for the Black hole process
or the resulting electroplated copper. My vendor is checking for this inf.
but in the meantime our lines will go down today unless I can get some
answers.


Original Question:

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

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information.
For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311
################################################################