TECHNET Archives

September 2002

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Tim Reeves <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 19 Sep 2002 10:41:01 -0700
Content-Type:
text/plain
Parts/Attachments:
text/plain (74 lines)
Mark,
TMA is thermo-mechanical analysis. It consists basically of measuring a mechanical property (the length) of the material as it is heated up. When the material reaches the glass transition temperature (Tg), the rate of change (slope) of the modulus changes, showing where the Tg is.

The Tg is dependent on cure, and repeating the test after exposing the sample to additional heat (which would advance the cure of the material if it is not yet fully cured) will change the Tg. It is this change in Tg which indicates the degree of curing. If the material is fully cured, the delta Tg should ideally be zero.

DSC (differential scanning calorimetry) does Tg measurement by measuring the *heat capacity of the material as its temperature is raised, giving similar information by a different method. Sometimes one method works better for some materials than another method. 

[the following is from  http://www.impactanalytical.com/tma.html]

Thermomechanical Analysis (TMA) is a thermal analysis technique used to measure changes in the physical dimensions (length or volume) of a sample as a function of temperature and/or time. TMA is commonly used to determine thermal expansion coefficients and the glass transition temperature of polymer or composite materials. 

A simplified explanation of the TMA technique may be described as follows. A specimen is placed onto the base of a quartz sample holder and a suspended quartz probe is lowered down and positioned so that it just touches the top surface of the sample. Different probe types of varying tip geometry may be used and, typically, the probe is loaded with some finite weight. The TMA sample holder assembly is then placed into a furnace unit and the vertical movement of the quartz probe is continuously monitored. Typically, TMA tests are run in a heating mode at some controlled heating rate. Probe displacement profiles are subsequently analyzed in terms of thermal expansion coefficients, softening temperatures, and/or the glass transition temperature. 

Timothy Reeves
Technical Service Engineer - Matsushita Electronic Materials, Inc.
4114 Heather Street, Forest Grove, Oregon, 97116
Main (503) 357-8695   Fax (503) 357-8868

* a slight simplification.



-----Original Message-----
From: Mark Hargreaves [mailto:[log in to unmask]]
Sent: Wednesday, September 18, 2002 5:07 AM
Subject: Re: Poyimide cure


Mark,
Sorry, no answer here, just another question.  What sort of cure tests are
the TMA & DSC ?

Thanks,
Mark Hargreaves
EMDS

        -----Original Message-----
        From:   [log in to unmask] [SMTP:[log in to unmask]]
        Sent:   Wednesday, September 18, 2002 1:09 AM
        To:     [log in to unmask]
        Subject:        [TN] Poyimide cure

        Technetters:
        I'm looking for information on the best way to confirm cure on a
polyimide board.  The particular part is a sequential lamination structure.

        My questions include:
        1.  Is the best time to confirm cure of polyimide immediately after
final lamination?
        2.  Do the polymers created require a specific cure test, e.g. is
TMA best, DSC, or other method?

        Also, can overcure be a problem with Polyimide?

        And, does this material offer special challenges with respect to gel
time, resin flow, etc?

        I've already heard differences of opinions, and am looking forward
to more avenues of knowledge from Polyimide experienced folks.

        Mark Julstrom
        Multek

---------------------------------------------------------------------------------
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
---------------------------------------------------------------------------------

ATOM RSS1 RSS2