Hi All,
The responses so far have talked about different damage mechanisms/failure
modes.
The damage mechanism described by Chris Robertson relates to the degradation
of the resin/reinforcement matrix itself. It depends on the resin system, Tg,
quality of bond to reinforcement fibers, and moisture content.
The other, of which Robert Tarzwell wrote, relates to the failure of the
interconnect structure of plated-through vias/holes. This mechanism, actually
mechanisms, because barrel cracking and inner-layer separation depend on different
mechanisms, have been extensively addressed in IPC-D-279 "Design Guidelines
for Reliable Surface Mount Technology Printed Board Assemblies," IPC-TR-579
"Round Robin Reliability Evaluation of Small Diameter Plated Through Holes in
Printed Wiring Boards," IPC-TR-486 "Report On Round Robin Study To Correlate
Interconnect Stress Test (IST) With Thermal Stress/Microsectioning Evaluations For
Detecting The Presence Of Inner-Layer Separations" and in my workshops.
Besides copper plating thickness, copper quality, PCB thickness, resin Tg, resin
content, hole diameter, hole quality, and other design details play a major role
in the temperature excursions and their numbers that can be withstood.
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, Fax: 386-437-8737, Cell: 386-316-5904
E-mail: [log in to unmask], Website: www.engelmaier.com
---------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------
|
