Just some thoughts,
Process control usually is driven by two components of a board shop.
Those two are the Customer's and the Internal Quality Org. Therefore it
would be very difficult to agree on what would be critical for every shop.
You may be able to highlight some "generic" critical variables that would
be consistent throughout the board shops.
When I was involved in setting up these major, minor, critical variable
in a board shop it became overwhelming with the number of variable to
monitor. I ended up implementing in phases. This allowed certain variable
to be monitored to see if really they would be beneficial. This process
took 2 years to come up to speed and even then it was still being worked on.
Even though it took some time, throughout the company was benefitting all a
long. These tools were the best for process controlling and predicting.
Todd Campbell
----------
From: TechNet-request
To: [log in to unmask]
Cc: [log in to unmask]
Subject: RE: Response to SPC Question.
Date: Tuesday, March 18, 1997 8:55AM
Rudy,
You know, this is a very good question. I would think that technical =
representatives from various suppliers and board manufactures should =
convene with the intent of specifically discussing and concluding what =
elements are critical to monitor and those that are not.=20
>From the conclusion reached, a process control presentation could be =
given to a larger group of board manufacturers that focuses on what =
really needs to be controlled. This could be part of an IPC forum or an =
independent seminar.=20
What I would really be concerned with is:
1. Would the various suppliers agree with one another regarding what is =
critical and what is =20
not?
2. How do you stop individuals from using the initial meeting as a
sales
=
objective? Do you =20
allow the sales representatives to attend the initial meeting?
3. How do cover the costs of such an adventure? =20
4. How many people would really be interesting in attending a =
presentation or seminar such=20
as this?=20
Just my thoughts,
Ed Cosper
Director Quality Assurance and Engineering
Graphic Electronics,
Tulsa, OK
----------
From: [log in to unmask][SMTP:[log in to unmask]]
Sent: Monday, March 17, 1997 3:40 PM
To: [log in to unmask]
Subject: Re: Response to SPC Question.=20
In a message dated 97-03-17 15:40:07 EST, you write:
>Simply put, we know that in etching, the speed, pressure, pH, =
temperature,
>and copper content has the most significant effect on the end item line
>width,
>
In reponse to above Rudy wrote:>
And one other really crucial item, which is rarely discussed, as it is =
so
hard to mearsure or control, that is the Cuprous ion content. However, =
the
Cuprous ion content,which is a function of the air throughput, can be
monitored by measuring the ORP. ORP is normally only measured on Cupric
Chloride etches, but I predict will be monitored on ammoniacal also. =
ORP, or
Cuprous ion content, is a VERY strong determiner of etch speed.
And this is my point, most folks are unaware of things like this. Also, =
most
folks think that measuring the titrated concentration of a resist =
stripper is
the best way to measure its strip speed. Not true. Much better is to
measure pH.
And so it goes.
The suppliers of chemistry should be advising the industry what to =
monitor.
You have any ideas on how this should happen? The mechanism to date =
has
been not great.
Rudy Sedlak
RD Chemical Company
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