Hi Krishnan,
Much of whether PCBs survive the soldering processes depends on how you have
specified your PCBs. TM-650 Section 2.4.24C - Glass Transition Temperature &
Z-Axis Thermal Expansion by TMA & Section 2.4.24.1 - Time To Delamination (TMA
Method) & Section 2.4.25C - Glass Transition Temperature & Cure Factor By DSC
are indeed very important; however, they are only part of the story.
The White Paper below can be of great help, because it not only fully
explains the need for the above properties, but also explains the differences between
Tg by TMA, DSC and DMA test methods. Of course, it also details all the other
parameters that are important for properly spec'ing PCBs.
Engelmaier Associates, L.C. just finished a multi-client study/white paper
titled: "WHITE PAPER REPORT: Recommendations for PCB FAB Notes and
Specifications in Printed Circuit Board Drawings for SnPb and Lead-Free Soldering
Assemblies, the Qualification of PCB Shops and Activities to Assure Continued Quality."
As indicated by the title, in this report recommendations are made regarding
appropriate specifications and ‘FAB Notes’ on drawings for printed circuit
boards (PCBs), general procedures to qualify PCB shops and to assure they would
be producing PCBs of good quality, and testing procedures to verify quality
and reliability. It contains examples—one for SnPb solder assemblies and one
for RoHS-compliant Pb-free solder assemblies—of ‘FAB Notes’ serving as general
specifications on PCB drawings, a basic questionnaire for new PCB shops to be
qualified meant as a suppliment to IPC-1710, as well as recommendations for
ongoing activities to assure that qualified PCB shops maintain the quality of
the PCBs produced by them. All the recommendations are fully researched and
referenced with 51 references.
The cost of the 25-page report is $495.-; it will be delivered as a pdf-file
upon receipt of a check or purchase order.
Attached please find a report outline together with part of a report section
to provide you with a sample of the report contents.
Regards,
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 386-437-8747, Cell: 386-316-5904
E-mail: [log in to unmask], Website: www.engelmaier.com
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