Valerie,
the TMA is much sensitive method to detect the Tg.  The DSC normally detect
heat release upon phase transformation, it is normally +5C above the TMA
detected Tg.  The insufficent cure at small degree will not be easily
detected by DSC for solid cured samples(depend upon the scan rate as well...
many expert can write about this more), but much easy to be detected by TMA
(CTE change... if your sample prep and equipment are good and vibration
free).  Just my 2 cents... (of course, the new equipment of DSC possibly can
detect smallest change... so don't kill me ... DSC expert).  It all depends
what you have in house.
Best regards,
                    jk

abcd

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of valerie St. Cyr
Sent: Thursday, November 16, 2006 2:57 PM
To: [log in to unmask]
Subject: [TN] TMA recommendation


Dear Tech Netters,

I have read that "IPC recommends" TMA for Tg determination (vs DSC or
DMA).

I have searched the site for a White Paper without finding one; I have
reread both specs looking for any language which would seem to imply one
is better than the other for determination of Tg given that the test is
one that reacts to thermal inputs, making it perhaps a more useful test
wrt to assessing thermal robustness given lead free assembly.

I am not trying to establish the differences between the tests. I am
trying to establish if IPC is on record somewhere with a recommendation or
preference.

Anyone know?

Thanks, Valerie

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