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Thermo Mechanical Testing of PB's and Laminates

S T and S Group provides laminate and PWB material evaluations using both TMA and DMA analytical techniques and following IPC TM 650 test methods and /or customer specific protocols. IPC tests include the following:

  1. TM 2.4.24C Glass Transition Temperature and Z-Axis Thermal Expansion by TMA

  2. TM Time to Delamination (TMA Method)

  3. TM Glass Transition Temperature of Organic Films – DMA Method

  4. TM Glass Transition Temperature of Organic Films – TMA Method

  5. TM Glass Transition and Modulus of Materials Used in High Density Interconnection (HDI) and Microvias -DMA Method 11/98

TM Glass Transition Temperature and Thermal Expansion of Materials Used In High Density Interconnection (HDI) and Microvias -TMA Method 11/98

A more useful test for the assembly industry is the time to delamination test for finished PWB’s and applicable to laminates. Suppliers of PWB’s continue to quote Tg as the key parameter relative to potential success in assembly and long term use. A better parameter is to evaluate the thermal robustness of both the lamination process AND the decomposition temperature of the material. At S T and S we utilize the T288 time to delamination test from the IPC TM 650 BUT we assign a requirement for survival with NO irreversible event for 2 minutes and no delamination for 10 minutes while the sample is held at 288˚C. This inexpensive but very quick and powerful test will also provide an estimated onset Tg1 for the material. Clients who have been told they are being supplied high grade materials can quickly learn if this is true or not. The images below are from supposed high grade materials with high decomposition temperatures (Td) that were in excess of 320˚C. The fact the material charred and separated at 288˚C confirms that the Td could not in fact be above 288˚C and was most likely well below it.

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