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DPRG: multiple different pcbs in one order?
Subject: DPRG: multiple different pcbs in one order?
From: Daniel Herrington
daniel at adc.nsc.com
Date: Fri May 1 10:29:56 CDT 1998
Has the group considered doing a PCB order that includes several
different boards? In other words, have a group board order that
anyone can add their small board to and save on the cost of the
tooling?
Example:
- --------
Jim Brown wants 24 of the H-Bridge boards fabbed.
Daniel Herrington wants 20 of the sonar boards fabbed.
Ed Koffeman wants 16 of the pic video boards fabbed.
???? wants 4 of the ??? boards fabbed.
The gerber plots for each board are stepped and placed on a single
layout for fabrication. Then each person only pays a percentage of
the cost of tooling:
Assume fab layout includes the following configuration:
6 H-bridge boards at 4 sq. in. each = 24 sq. in. total
5 sonar boards at 4 sq. in. each = 20 sq. in. total
4 pic video boards at 5 sq. in. each = 20 sq. in. total
1 ??? board at 10 sq. in. each = 10 sq. in. total
- -----------------------------------------------------------
Total area per large board: = 74 sq. in.
Number of large boards (each one having the configuration listed
above) to be fabbed would be 4.
Total area: = 74 sq. in. x 4 = 296 sq. in.
So the cost would be divided up as follows:
Jim pays 24/74 of the tooling cost and cost of sq. in.
Daniel pays 20/74 of the tooling cost and cost of sq. in.
Ed pays 20/74 of the tooling cost and cost of sq. in.
???? pays 10/74 of the tooling cost and cost of sq. in.
(Plus some small percentage for wasted space on the overall layout.)
The individual boards would have to be cut apart from each large
board upon fab completion.
Here are my calculations of actual cost, based on AP Circuits pricing:
Cost Equation:
- --------------
(sq. in. cost) (tooling cost)
TOTAL AREA x $0.68 + $48.00 = THE COST IN US$
Therefore,
296 x $0.68 + $48.00 = $201.28 + $48.00 = $249.28 + shipping
So we have the following totals:
Together: Alone: Savings:
--------- ------ --------
Jim pays $80.85 instead of $113.28. $32.43
Daniel pays $67.38 instead of $102.40. $35.02
Ed pays $67.38 instead of $102.40. $35.02
???? pays $33.69 instead of $75.20. $41.51
(Not considering shipping and a few dollars more for wasted space
between boards.)
Has anything like this been proposed/done before? I would guess there
are disadvantages to doing it this way, including the following:
1. You have to wait longer for others to put the finishing touches on
their individual boards before placing the order.
2. Someone (hopefully Jim or some other PCB-knowledgeable person) would
have to put the overall layout together in a gerber processing
tool, and make sure that there were no errors in the overall
layout. Of course, each person would want to review the layout
before the job is sent out.
3. The pricing would have to be approximate, no squabbles over a few
dollars difference in each person's cost calculations.
4. The boards would have to be cut apart, preferably with a bandsaw
or other precise tool (router?).
5. There would be no guarantees that individual boards would work
100%.
6. There would be a maximum allowable area for the large board, based
on AP Circuits' requirements.
7. Each person would have to choose a total number of his/her boards
to allow the total number of large boards to come out to a
multiple of two (a requirement of AP Circuits).
What do you think? Is anyone interested in pursuing this? Has it
been done before, successfully or unsuccessfully? Is it worth the
trouble?
Best Regards,
Daniel Herrington
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