PCB VACUUM SYSTEM DESCRIPTION
I have been using the above system for holding down my circuit boards while I machine the traces and drill the holes.
This is the vacuum chuck. Constructed from 3/8 inch thick by 4 inch wide by 6 inch long aluminum it has .07 inch wide by .065 inch deep
air channels. It also has an oring around the outside contour. The board must overlap the oring inorder to maintain a vacuum seal. I cut
my circuit board blanks to 4 x 6 inches before I place them on the chuck for circuit routing.
air channels. It also has an oring around the outside contour. The board must overlap the oring inorder to maintain a vacuum seal. I cut
my circuit board blanks to 4 x 6 inches before I place them on the chuck for circuit routing.
The next component is the vacuum pump. This pump is made by GAST and is a rotary vane style pump. I like the rotary vane pumps
because they are quiet and durable. This pump is rated for 20 inches of mercury vacuum, and a flow rate of 1.5 cfm. You dont need to
use the same exact pump for your system, but having 20 inches of mercury vacuum is about the minimum I would recamend. You can
find pumps that pull more vacuum and that will be an advantage if you can find one in your price range.
because they are quiet and durable. This pump is rated for 20 inches of mercury vacuum, and a flow rate of 1.5 cfm. You dont need to
use the same exact pump for your system, but having 20 inches of mercury vacuum is about the minimum I would recamend. You can
find pumps that pull more vacuum and that will be an advantage if you can find one in your price range.
As you can see in this photo, I have designed the chuck with holes in the side and on both ends. This is a feature that has made circuit
board fabrication much less frustrating for me.
I designed the chuck to be precisely 6 inches long. Knowing this length I can place screws in the holes in the edges of the chuck, and use
them as board stops. These stops effectively locate the board on the chuck. This makes it possible for me to remove the board from the
chuck, and then place the board back on the chuck and know that I am in the same position I was when I started. At times it is nessasary
to rerun part of the board, or fix somthing, so this is a great advantage.
The next thing the board stops do is assist in the process of making double sided boards. After I mill side one, I drill all the holes only half
way through the board from side one. Now I apply contact paper to side one and flip the board over. Now I can move the board stop
that was on the left end of the chuck to the right end of the chuck. I dont have to pick up my board zero location because I know its 6
inches from the other end exactly.
Now after I mill the traces on side two, its time to drill all the holes again, and this time just drill past center of the board, and you now have
through holes in your board without drilling into the vacuum chuck. The contact paper that was applied to side one is now preventing the
loss of vacuum that would occurr through the holes.
board fabrication much less frustrating for me.
I designed the chuck to be precisely 6 inches long. Knowing this length I can place screws in the holes in the edges of the chuck, and use
them as board stops. These stops effectively locate the board on the chuck. This makes it possible for me to remove the board from the
chuck, and then place the board back on the chuck and know that I am in the same position I was when I started. At times it is nessasary
to rerun part of the board, or fix somthing, so this is a great advantage.
The next thing the board stops do is assist in the process of making double sided boards. After I mill side one, I drill all the holes only half
way through the board from side one. Now I apply contact paper to side one and flip the board over. Now I can move the board stop
that was on the left end of the chuck to the right end of the chuck. I dont have to pick up my board zero location because I know its 6
inches from the other end exactly.
Now after I mill the traces on side two, its time to drill all the holes again, and this time just drill past center of the board, and you now have
through holes in your board without drilling into the vacuum chuck. The contact paper that was applied to side one is now preventing the
loss of vacuum that would occurr through the holes.
As you can see from the above
photos, its possible to make large
and small boards, even boards with
complex contours can be made on
this chuck. The key is to start with
a 4 x 6 inch blank of circuit board
material, then when the board is
completed use the machine to route
the outside contour of the board
while it is on the chuck. As you
route the ouside of the board dont
go through the board, but leave a
few thou of material and then when
you remove the board from the
chuck, just break off the unwanted
material around the outside.
I have been using eagle to design
the boards, and then a ulp for eagle
called PCB-GCODE. This
program allows you to generate all
the nessasary gcode for your circuit
board. Big thanks to the developer
of PCB-GCODE John Jonhson:)
If you have questions about this
article, dont hesitate to send an
email to:
kn6za@hotmail.com
thanks,
Andrew