Hi Bryan,
The STII parameter has been discussed in my reliability column in Global SMT & Packaging magazine in January 2006—I have attached a copy.
It is also discussed, together with lots of other things, in my 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 being much more specific than IPC-4101B, a basic questionnaire for new PCB shops to be qualified meant as a supplement 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 discussed, carefully researched and referenced.
The cost of the report is $495.-; it will be delivered as a pdf-file immediately upon receipt of a check, money transfer or purchase order.
Updates will be sent automatically and at n
o additional cost—I am currently shipping v.08 with some 45 pages and over 80 references; and have started work on update v.09.
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
-----Original Message-----
From: Bryan Montney <[log in to unmask]>
To: [log in to unmask]
Sent: Wed, 12 Nov 2008 4:48 pm
Subject: RE: [TN] Tg specification
Werner,
Would it be possible to send me the STII method that Paul mentioned below. I'm
looking for something concrete possibly in a guideline format that our quality
dept. can use. Do you have something published or know of a good resource for
this?
Regards,
Bryan
-----Original Message-----
From: Paul Reid [mailto:[log in to unmask]]
Sent: Wednesday, November 12, 2008 3:35 PM
To: Bryan Montney
Cc: [log in to unmask]
Subject: RE: [TN] Tg specification
Just write to Werner and request his method.
I'll cc him on this email.
PR
-----Original Message-----
From: Bryan Montney [mailto:[log in to unmask]]
Sent: Tuesday, November 11, 2008 3:57 PM
To: Paul Reid
Subject: RE: [TN] Tg specification
Paul,
Where could I find information on Werner's STII method and the various
parameters you mentioned?
Regards,
Bryan Montney, C.I.D.
Adaptive Micro Systems LLC
Voice: (414) 410-0639
Fax: (414) 357-2028
Internet: http://www.adaptivedisplays.c
om/
Email: [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Paul Reid
Sent: Tuesday, November 11, 2008 1:57 PM
To: [log in to unmask]
Subject: Re: [TN] Tg specification
Just a comment for what it is worth:
Tg is an indicator of material robustness but it is not definitive. There are
high Tg materials (170°C) that are not robust in a tin/lead application if the
board is fabricated with sequential lamination.
Werner's STII method has a three parameter input (I believe) which includes Tg.
His method is much better at quantifying a materials' likely hood to be robust
in a given application than considering Tg alone.
I have not heard of specifying Tg as requirement in an end use environment.
Specifying a Tg minimum may not be in your companies best interest in order to
guarantee a robust product in a given end use environment.
Testing material robustness is readily achieved with thermal cycle testing.
Thermal cycle testing allows one to rank robustness of various materials. I know
from experience they will not lineup in descending order of Tgs.
Sincerely,
Paul Reid
Program Coordinator
PWB Interconnect Solutions Inc.
235 Stafford Rd., West, Unit 103
Nepean, Ontario
Canada, K2H 9C1
613 596 4244 ext. 229
Skype paul_reid_pwb
[log in to unmask] <mailto:[log in to unmask]>
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bryan Montney
Sent: Tuesday, November 11, 2008 1:49 PM
To: [log in to unmask]
Subject:20[TN] Tg specification
I'm looking for a guideline or resource (IPC spec?) on how to select and specify
the proper Tg for a given design? I'm not talking about process wise (Tg140 is
acceptable in our lead-free processes), but design wise.
For example, is Tg140 material sufficient for a board running 80amps through it
and sitting in an enclosure on a hot summer day in Arizona?
Also, I'm looking for how best to test the Tg robustness during production. Any
help would be greatly appreciated.
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