Hi,
I has been wondering that how can I know a magnifier's magnification without reading the numbers on the lens? We have some old magnifiers that have not any number on them. Does anybody have some neat way to verify the magnification?
Jiang Ping
----- Original Message -----
From: Stephen R. Gregory
To: [log in to unmask]
Sent: Saturday, July 21, 2001 6:49 AM
Subject: Re: [TN] Inspection Criteria
Hi John!!
Like Kathy said, magnification for inspection is spelled out in the 610, and
the J-STD too...I would quote them, but I don't have them in front of me...I
do know 30X is pushing things a whole lot!
This issue is a never ending debate. Are your inspectors finding REAL
defects? I go through this stuff quite a bit too...so I understand your
frustrations.
An ol' crusty QA manager told me a while back, is that there are two kinds of
inspectors, those that inspect to accept, and those that inspect to reject.
He also said that if it takes more than just a couple of seconds to decide if
something is good or bad, it's probably good...leave it alone.
I go through this stuff all the time...especially with class-II stuff here.
The latest battle has been with barrel-fill. You're allowed a 75% barrel fill
with class-II stuff...
The inspectors complain that they can't tell if it's 74% or 76%, so they
reject everything that doesn't have a full barrel fill...(where's my
Excedrin?). In turn, this just conditions all our operators to touch-up
things that they don't need to touch-up...and it goes on and on, and on, and
on...
Have tried to talk to them about the issues when re-heating solder joints,
(intermetallics, and that it's NOT increasing the functionality or
reliability of the joints).
But it's like like I'm talking to a wall. Inspectors, as you have learned,
need to feel that they must find something...I've only met a few inspectors
that I can hand a board to, and get it back without red-arrows on it
somewhere...whether there is defects on it or not. That's their job (in their
mind), to find something wrong...if they can't find something wrong, then
they've missed something, and not done their job...
If it sounds like I'm getting down on inspectors, I'm really not. There's
been more than just a few times in my career that I was really glad that
there was a very detailed, picky, inspector, that caught a mistake from
production that was pretty serious before we shipped to the customer...stuff
happens. But on the other hand, there has been times that they've been so
focused on solder joints, that they've totally missed that there were
components installed, that were wrong values, wrong polarity, etc...
I'm not saying that you need a QA inspector to tell you when you load
something wrong, that responsibilty should fall squarely on the set-up and
first article inspection from the people that are running the line, but you
know what I'm driving at...
-Steve Gregory-
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