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December 1998

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Subject:
From:
Matt Curtis <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 2 Dec 1998 13:46:08 -0600
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Jim:
I think you have a good point about J-STD 001B, although I do believe that can cause problems when using multiple-vendors. 
Matthew Curtis
Burnett Technical Training Center
Austin, Texas 78752
512-459-1110

>>> <[log in to unmask]> 12/02/98 12:52PM >>>
Bill Dasprzak:
- I think that you need to consider accumulating defect data on multiple pwb's
(of the same p/n) that you are processing.  Folks running small pwa's with a
small number of connections would have a devil of a time (for example one
defect on a pwa with 300 connections probably puts you over the 0.3%
threshold).
- Re par. 9.1.2, I always thought that the intent of that paragraph was to
make sure that the defect rate calculations were based on a standardized
method of determining the number of opportunities (instead of counting a pth
as 2 defect sites - one on top of the pwb and one on the bottom of the pwb)
and telling everyone to just count each interconnection site once (whether
thru-hole or not).
- "Touching up" a solder joint after machine soldering should not be necessary
if the process is in control.  If you don't record the number of "touch-ups"
as defects (and feed that information up-stream) you may never discover that
you are dealing with a component lot which has poor solderability.  In
addition, and more likely, the folks will be touching up things that "just
don't look right to me" and spending a lot of time and money to reduce the
reliability of the product (if it ain't a real defect, leave it alone).  Hand
soldering (add parts) after machine soldering is usually done in such limited
quantity that classic SPC is seldom applicable.
- Re corrective action system, paper work and record keeping.  One of the
great things about the J-STD-001B is that it lets you do what ever makes sense
to you, as long as your customer agrees.  I've never seen identical methods
used in different companies, so I don't know if there is a "typical way" to
perform/document corrective actions.  Generating a "corrective action report"
for a single defect confuses me a little.  Some method of identifying the
defect should exist and be factored into the process control system.
Hopefully the "corrective action report" you refer to is a "PRODUCT"
corrective action and not a PROCESS corrective action.
Jim Moffitt, Moffitt Enterprises Consulting

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