IPC Committee Revises DSC Test Method for Tg


Reading time ( words)

IPC’s 3-11 Laminate/Prepreg Materials Subcommittee has announced the publication of the latest revision of the test method for the determination of glass transition temperature (Tg) of copper-clad laminates (CCL). IPC-TM-650 Method 2.4.25 utilizes Differential Scanning Calorimetry (DSC) to measure the Tg of the base materials for rigid printed circuit boards. The Tg is one of the characteristics used to estimate the thermal reliability of materials used in electronics.

The key change in the document clarifies what is and what is not a phase transition as the temperature approaches the Tg for the first time. In the past, the unusual exotherms or endotherms could be interpreted as being a Tg. There are a number of reasons cited for these spurious events including stress relief, release of moisture and evaporation of residual solvent. The Pre-Scan step is needed to make the baseline more stable for the calculation of Tg1 and Tg2. The Pre-Scan takes the temperature to about 10°C above the predicted Tg1, then the sample is cooled immediately back to the starting point temperature. The determination of Tg1 is then carried out by a second scan which terminates at either 175°C or 190°C depending of the type of epoxy resin system. At the termination temperature, the specimen is held at isothermal conditions for 15 minutes before cooling again to the starting point temperature. Finally, a third scan is conducted to determine Tg2. It is Tg1 and Tg2 that are used to calculate either the cure factor or the delta Tg.

All of the IPC-TM-650 test methods can be found free of charge at the IPC website, www.IPC.org under the “Knowledge” tab. 

Share


Suggested Items

In Terms of Experience, a 10,000-foot View of China

01/17/2018 | Barry Matties, I-Connect007
In the past 30+ years of PCB manufacturing in China, you would be hard-pressed to find someone more connected to the pulse of the Asian market than Gene Weiner. Barry Matties met with the industry veteran at HKPCA to get his take on the show, the current and future market conditions of China, and any effect the new U.S. administration might have on trade relations going forward.

The Benefits of Coming Together to Form a Global Reach

01/16/2018 | Patty Goldman, I-Connect007
At productronica, MacDermid Enthone Electronics Solutions and Alpha Assembly Solutions had one large combined booth to promote the companies’ integration. Over a buttered pretzel (don’t knock it until you’ve tried it), we talked about the newly amalgamated company, something everyone in the company is quite enthusiastic about.

Weiner’s World—December 2017

01/02/2018 | Gene Weiner, Weiner International Inc.
Hold on to your seats! 2018 will be a year full of rapid changes, surprises, and growth. M&A activities will flourish. The supply chain will suffer shortages and changes as demand increases, copycats will rush to market, and new markets and potential suppliers will vanish before they are established.



Copyright © 2018 I-Connect007. All rights reserved.