Albert

How long is a piece of string? It depends on how quickly the
contaminants dissolve. I suggest you do two or three tests for an hour.
You will observe that the resistivity drops fairly rapidly and then very
slowly. Draw a straight line approximating the last 15 minutes backwards
to zero time. Draw another straight line approximating, say, the first
five minutes. Note the value and the time where the two lines intersect.
If the value is > 3/4 of the final value, then double the time to
intersection. If >1/2, then quadruple the time. If >1/4 then octuple the
time, if <1/4 then 16 times the time. This is only a **very** rough
guideline until you acquire sufficient experience to judge when you
approach asymptote.

Brian

> ¿àÁJ·½( sylai ) Q80_5381 wrote:
>
> Hi TechNetters,
>     I need some help regarding Cleanliness. Now I have an automatical
> test machine whose name is omega 600. I usually test 10 minutes
> for cleanliness of PCB. Can anyone give me the best advice about the
> test time of omega 600 machine which is used in PCB and tell me the
> cause ?
> Thanks,
>
> Best Regards,
>
> >Albert Lai
> > TEL : 886-3-323-1111 ext 5381
> > FAX : 886-3-323-6611
> > E-MAIL : [log in to unmask]

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