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. 
>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. 

What I would really be concerned with is:

1.  Would the various suppliers agree with one another regarding what is critical and what is    
     not?

2.	How do you stop individuals from using the initial meeting as a sales objective?  Do you   
      allow the sales representatives to attend the initial meeting?

3.   How do cover the costs of such an adventure?  

4.   How many people would really be interesting in attending a presentation or seminar such 
      as this? 

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. 

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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