IRG4BC40FD IRF [International Rectifier], IRG4BC40FD Datasheet - Page 5

• Manufacturer Part Number: IRG4BC40FD
• Description: Fit Rate / Equivalent Device Hours
• Manufacturer: IRF [International Rectifier]

IGBT / CoPack
Quarterly Reliability Report
Traditionally, reliability results have been presented in terms of Mean-Time-To-Failure
or Median-Time-To-Failure. While these results have their value, they do not
necessarily tell the designer what he most needs to know. For example, the Median-
Time-To-Failure tells the engineer how long it will take for half a particular lot of
devices to fail. Clearly no designer wishes to have a 50% failure rate within a
reasonable equipment lifetime. Of greater interest, therefore, is the time to failure of a
much smaller percentage of devices say 1% or 0.1%. For example, in a given
application one failure per hundred units over five years is an acceptable failure rate
for the equipment, the designer knows that time to accumulate 1% failure of that
components per unit, then no more than 0.1% of the components may fail in five
years. Therefore, the IGBT / CoPack reliability or operating-life data is presented in
terms of the time it will take to produce a prescribed number of failures under given
operating conditions.
To obtain a perspective of failure rate from an example, let us assume that an
electronic system contains 1,000 semiconductor devices, and that it can tolerate 1%
system failures per month. The equation for the device failure is:
In the case of the example,
or 14 FITs or 14 failures per 10
= Proportion allowed system failures
=
0.01 Failures
Time period
720 Hours
Fit Rate / Equivalent Device Hours
9
devices hours.
X
X
No. of devices
1000 Devices
1
1
X
=
10
10
9
9
=
=
14 FITS
FITS
Page 5 of 35