Per IPC-HDBK-830 Appendix D;

(b) Differential Scanning Calorimetry (DSC)
Differential Scanning Calorimetry (DSC) is a technique for determining the Tg of a coating. DSC measures heats and temperatures of transitions, i.e. the amount of energy absorbed or released by a sample as it is heated, cooled, or held at a constant temperature through thermodynamic events such as melting or crystallization. Properties that can
be measured via DSC are Glass Transition Temperature (Tg), Melting Temperature (Tm), Heat of Fusion, Degree of Cure, and Crystallization Temperature.

(d) Dynamic Mechanical Analysis (DMA)
Dynamic Mechanical Analysis (DMA) is a technique for determining CTE and Tg. DMA measures changes in the mechanical (viscoelastic) behavior (modulus and damping) of polymeric materials as a function of temperature, time, frequency, stress, or combinations of these parameters. Film, fiber, and bulk material samples can be measured. The DMA also operates in a constant force mode to perform TMA Testing. Properties that can be
measured via DMA are Elastic Modulus, Flexural Modulus, Poisson's Ratio, Tg, CTE, Creep/Recovery, Gel Point, and Heat Deflection.

I hope this helps!

David A. Douthit
Manager
LoCan LLC

Gary McCauley wrote:

One is measuring heat absorption and the
other mechanical movement?

gary mccauley

-----Original Message-----
From: Gerard O'Brien [mailto:[log in to unmask]]
Sent: Thursday, September 20, 2001 10:23 AM
To: [log in to unmask]
Subject: [TN] Tg measurements by DMA

When testing Tg with DSC, the TM-650 test method calls out for the test to
be run with the copper clad still attached and that if removed to expect an
8 to 15 degree reduction in values. For DMA it does not reference testing
with copper clad or removed. Can anyone give me the reason why?

Regards

Gerard O'Brien

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