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March 2000

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Subject:
From:
"Richard D. Jackson" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 10 Mar 2000 11:45:52 -0600
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Oh man let me tell you the nightmare you are about to embark on.

At my last employer they allowed the board house to set panel count and
size. Now this is not to much of a problem if you only deal with one board
shop but we used 4 board shops. And of course every one of them did
something different. So for the same Assembly I had to have 4 stencils (
one for each of the different board shops ) 4 pick and place programs (
every one of them used different rail and step and repeat sizes ). Talk
about a major nightmare and this doesn't count for the times they needed a
quick turn on boards and did not tell you about it until they wanted to run
the boards that is. The process group was constantly writing new programs
and buying stencils.

Now how did they get into this mess and what did I do to fix it? Well they
got into this by letting the sales department drive purchasing and
manufacturing. The whole reason for doing this from the sale's departments
perspective was that by letting the board shop set the panel and rail
widths we got better pricing ( any where from 10 to 50 cents per board) and
hey we all know what the sales people did they let the board house do what
they wanted. But what nobody did until I got there was explain how much
this was costing us in down time and tooling. After I got though with
collecting all of the data my conclusions  were  we ended up spending about
$1.00 per board to save 50 cents per board. This former employer no longer
lets there board house set the rules. But they do let the board house that
will be the primary supplier for the particular board have input into how
we layout our panels before we set it into stone. That way sales gets what
they want, a cheaper board, and manufacturing gets what they want a
consistent board layout across venders.

So what I would do if I were you, get the primary board supplier's input
for a optimal panel layout. Then take that and put it on your drawing and
fab instructions that way if you do go to another board shop they will have
to make the board to your drawing that now includes the panel layout. I
always include a panel layout in fab instructions but I also ask the board
house for input before laying it in stone. With the board shops help I can
get a lower cost board.

Later
Richard Jackson




                    Ken Patel
                    <[log in to unmask]        To:     [log in to unmask]
                    COM>                 cc:
                    Sent by:             Subject:     [TN] Single v/s panel info on drawing & gerber
                    TechNet
                    <[log in to unmask]
                    ORG>


                    03/10/2000
                    11:21 AM
                    Please
                    respond to
                    "TechNet
                    E-Mail
                    Forum.";
                    Please
                    respond to
                    Ken Patel






Assembly folks / layout guys / Stencil guys,
We received a fab drawing and gerber for single board but in reality it's a
panel or an array. My design guy says that leave it to fab house on
selection of panel size. It's a common practice. He thinks that different
fabs work with different materials and processes.

I do not agree with him for the following reasons. What do you think guys,
particularly in assembly house!
(1) Stencil making will be a trouble one as person is going to order based
on gerber unless someone tell him else he has to order another one.
(2) What if the job is shifted to different fab vendor. We have to start
complete process again if panel size is different.
(3) Machine programming modification,
(4) New wave fixturing.....and many more

Any valuable inputs will be appreciated.

re,
ken patel
______________________________________________________
Ken Patel                       Phone:  (408) 490-6804
1708 McCarthy Blvd.             Fax:    (408) 490-6859
Milpitas, CA 95035              Beeper: (888) 769-1808

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