Dear BGA Reliabilty Experts:

I have done FEM simulations for BGAs and have found some results I cannot
explain. Hope you can enlighten me on it.

I modeled BT-based BGAs and tape-based BGAs (both cavity up) under 0-100C
1 cycle per hour condition. For BT BGAs, with the same die size, the
larger the package, the better the mean fatigue life. This phenomina may
be attributed to die/package ratio, the bigger the die/package ratio, the
worse the fatigue life. However, for tape BGAs (tape substrate is much
thinner than BT substrate), the result is the opposite. With the same die
size, the larger the package, the worse the fatigue life.

Can someone explain why the difference between BT and Tape BGAs?

Best regards,


Yuan Li

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