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ORS has developed a method
to characterize the outgassing of a large variety of
samples. This method could be described as follow.
The Raw Sample may have many forms like :
Metal
(Kovar, ...)
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Adhesives (Epoxy, ...)
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End
products (Microelectronics packages , ...)
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Typical
study procedure:
1. The sample is hermetically sealed in a clean and
dry glass ampoule under controlled atmosphere (dry Nitrogen
for example).
2.
A thermal stress is then applied and the sample outgasses
in the hermetic enclosure.
3.
Finally, an IVA™ test
is performed on the ampoule.
4.
The test results give the complete gas picture (sealing
atmosphere + outgassed substances).
Application
Examples:
Hydrogen Outgassing from Package Kovar
Hydrogen is known to outgass from Kovar alloy when submitted
to high temperatures.
This phenomenon is particularly
critical in AsGa technology, for example, where
hydrogen
can lead to failures. Therefore, focus is put on lowering
and controlling
the hydrogen level.
The
glass ampoule sealing can prove very valuable to characterize
Hydrogen
outgassing from metal packages. The various
package elements (lid, walls, …)
can be separated
and outgassed individually. Various bake time and temperatures
can be used to optimize pre-seal prebakes.
Note:
It is possible to seal a sample several times. A possible
application is to draw an outgassing curve as a function
of time for a specific temperature.
Epoxy Outgassing
Moisture and CO2 are generally the main compounds outgassed
from epoxy materials mainly because of under curing
or over curing problems.
Epoxy
materials have specific outgassing signatures which
are easily identified and quantitated with the use of
glass ampoules; this technique is useful to optimize
pre-seal bakeout and to identify thermal stress by-products.
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