Hello,
First of all, thanks for the valuable advice from all
contributors.
May be I had some misleading, (actually I was being
misleaded after reading my previous post mail). I would like to
clarify that:
I have seen some test results of surface insulation done by
other people (not me) that the resistance readings decrease initially
in the first few hours (say 24 hours) and then increased
slowly. Based on all of your comments, can I assume that there may have
comtaminants on the board surface initially and caused decrease in resistance
readings. The contaminants then evaporate out and resulted in
gradually increase in resistance reading, is it? I have forgot the
testing temperature of this test result, as per advise, the resistance
will not increase if we decrease the testing temperature? please help to
advise. I want to ask this because it is strangle for me that some test
results showed decrease in resistance reading during the whole test period while
some showed as above mentioned.
Brian, would you please help to elaborate the difference
between true SIR and ECM and what is ECM, as I am not familiar with
these tests actually. What is bias voltage mean? Do we need to
apply it on coupons throughout the test period in ECM or just when we
need to measure resistance.
Condensation on coupons shall be prevented because of ionize
the contaminants?
Thanks
Leecp