~bowing in awe at your wisdom and insight, ok, well sort of~
I wish I could have stated my thoughts so well, I am in agreement with you.
Franklin
----- Original Message -----
From: Jack Crawford <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, November 10, 1999 12:39 PM
Subject: Re: [TN] Nonconforming process indicators
Just a few words on terminology.
The term "nonconforming" is used in several IPC published documents and
unfortunately don't always have the same intent. Some docs (particularly
those dealing with boards) only identify two conditions - acceptable and
nonconforming. In that case, nonconforming means defect and requires
dispostion. IPC-A-610B added "nonconforming" with every occurrence of either
the Process Indicator or Defect conditions. In 610B then, the official
interpretation nonconforming
Except for some explanatory words up front, the C revision to 610 will not
use the word "nonconforming". In the case of 610B, I would encourage you to
put a filter on the word and ignore it.
Because 610B is still the most current published assembly acceptance
document, you are stuck with that word all the way through, and your request
for clarification is not the first one we've received.
Now to the main part of your question. Of course, you are aiming towards the
Target condition of everything you build, and you're comfortable with
Acceptable. Defect is understood--it requires disposition to determine what
to do with the "bad hardware". But what about the hardware that doesn't meet
Acceptable, but isn't so bad as to be a defect, or that a rework operation
is likely to generate more failure mechanisms than are corrected? The most
common option is to identify them a name that reflects the process may be
slipping--a process indicator.
Of course, identification of an indicator suggests you would do something
with the knowledge that the process is potentially going out of control. If
you have a functioning process control program, you would track those
process indicators and the process engineers would use them to tweak as
necessary. Ideally, if the program is working, process indicator counts
slowly increase until a threshold is reached, corrective action is taken,
and process indicator counts reduce substantially. Continuous process
improvement comes to mind.
So now we watch the TechNet responses and see if anyone is willing to state
they actually track and use process indicators like J-STD-001 says you
should.
Jack
==========================================
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Manufacturing, March 12-16, 2000, Long Beach, California.
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-----------
Jack Crawford, IPC Director of Assembly Standards and Technology
2215 Sanders Road, Northbrook IL 60062-6135
[log in to unmask]
847-790-5393
fax 847-509-9798
>>> Tim Devaul <[log in to unmask]> 11/10/99 12:08PM >>>
I am in the process of switching from my company's internally developed
standards to IPC, the only outlying issue is how we are going to handle
nonconforming process indicators as they arise. Could I get some feedback as
to how your companies handle
them?
Thanks, Tim
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