Classification:
Prologue:
Epilogue:

Rudy:

You really want to measure the process settings, and do enough process
experiments to know that within x sigma of  nominal process condition, all of
your product will be within product spec.  The principal is to build in the
quality, not inspect it in.  This principal is well documented behind the
"6-sigma" initiative at Motorola.  SPC  is statistical "process" control.
Measuring the product variables occasionally in detail is good, but with a good
SPC program you should be able to use inspection audits on a few critical
product parameters, and focus on keeping your processes within specific
windows.  The windows that you chose will be based upon your own Design of
Experiments for your processes  (things like solder paste age, reflow
temperatures, Cu plate times and temps, etc, depending upon your business and
your processes).

Hope this helps

Jim Herard
IBM Microelectronics
PCB Quality Engineering
---------------------- Forwarded by Jim Herard/Endicott/IBM on 03-17-97 01:48 PM
 ---------------------------

        TechNet-request @ ipc.ipc.org
        03-16-97 11:57 AM


To: TechNet @ ipc.org@internet
cc:
Subject: Re: REQUESTED SPC INFO ( 5 PAGES)

To this end, would like to ask what may be naive question, but oh well...

In the ideal world, does SPC want to measure results of a process, such as
line width produced in a developer or etcher, or does it want to measure
process conditions, such as pH in a developer or etcher?

Guess the reason why I ask is that if measuring process conditions is at
least partly the answer, we should likely have some input as to what is best
things that should be measured in each process.   The industry is moving
towards new areas here.

Rudy Sedlak

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