Life-time test investigation of joints formed by IR and Vapour Phase reflow soldering

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Supervisor:
Dr. Krammer Olivér
Department of Electronics Technology

The dissertation deals with the expected lifetime analysis of the solder joints made with infrared and vapor phase reflow soldering. Based on the literature, I reviewed the accelerated lifetime test methods, and also the models which describe them. Furthermore the phisycal proccesses of the different reflow soldering. Based on the literature survey, I expect the vapor phase reflow soldering technology to be better. In the experiment, I set the thermal profile of both types of soldering, that the heating factor should be around 1000 °C∙ s. I used HAST and TS accelerating lifetime test to determine the expected lifetime. The surface of the solder joint was investigated by stereo-microscope, and then I made shear strength measurements.

The initial shear strength of the solder joints were made with vapor phase soldering was 22,5 N, and after 200 cycles of TS test and 1600 hours of HAST that decreased to 19 N (16% decrement). By infrared technology, the initial shear strength was 24,8 N and after the accelerated lifetime tests, that value lowered to 17 N (32% decrement). After 200 cycles of TS and 2000 hours of HAST both types of soldering, in all case PAD lifting occured.

The calculated accelerated factor of HAST is 493, and the TS test’s factor is 90,2. The expected lifetime of the solders were made with VPS is 811097 hours (93 years), and the ones, which were made with IR technology is 612695 hours (70 years).

In case of both types of reflow soldering technology, the solder joints can be qualified as good. Based on the the shear strength values after the accelerated lifetime test, and by the calculated expected lifetime, the quality and reliability of the solder joints made with VPS is better.

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