TEMPERATURE CYCLING (T/C) Unbiased

Conditions

Temperature:

Tmin = - 55°C

Tmax = + 150°C

Bias:

Unbiased

Duration:

2000 Cycles

Test points:

250,500,1000,1500,2000 Nominal

Purpose

Failure Modes

Sensitive Parameters

Temperature Cycling simulates the extremes of thermal stresses which devices will

encounter in the actual circuit applications in combination with potentially extreme

operating ambient temperatures. Some equipment is destined to be used in extreme

environments, and subject to daily temperature cycles.

The primary failure mode for temperature cycling is a thermal fatigue of the silicon / metal

interfaces and metal / metal interfaces. The fatigue results from thermomechanical

stresses due to heating and cooling and will cause electrical or thermal performance to

degrade.

will begin to increase well before any electrical effect is seen.

If the degradation occurs at the wire bond / die interface or the wire bond / bond post

The thermal impedance, when measured during this time, may appear to decrease or

change erratically.

The mechanical stresses from the temperature can also propagate fractures in the silicon

when the die is thermally mismatched to the solder / heat sink system. These fractures

will manifest themselves in the form of shorted gates or degraded breakdown

IGBT / CoPack

Quarterly Reliability Report

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