Quote:
Originally Posted by simplechamp
Pdelcast, is there any way you can give a brief description (in lamen's terms) of what each machine does in the manufacturing process?
I understand what the placer does, but not really sure about the stencil printer and chipshooter.
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Sure --
The solder is printed on the board by the stencil printer. The solder comes in a form called "solder paste" (it has about the consistency of toothpaste -- it's made of microscopic solder balls suspended in a liquid flux, and costs about $80.00 a pound.) We have stencils made for the circuit boards from .005" thick stainless steel in a 29"x29" frame. The stencils are cut by laser. Where ever there is an opening in the stencil, the solder is deposited on the circuit board. The job of the stencil printer is consistency -- it aligns the stencils and the circuit boards to within 2 ten thousandths of an inch, squeegees the solder paste onto the circuit board through the stencil, cleans the stencil, checks the paste on the board to make sure the paste coverage is correct without any excess paste, and then sends the board to the chipshooter by conveyor.
The Chipshooter is a high speed placement machine that uses a 30 position rotary head. Chipshooters are faster than regular placement machines by about a factor of 2 to 3. BUT, they are limited in the type of components they can place on the board (they can't place really heavy or odd-form components.) We have two chipshooters, one with four heads, and one with just one head (our new machine.)
Here's a video of a chipshooter of the same brand as ours. This model has one head. Our new single-head machine is actually FASTER than the machine in this video -- the video shows an older rotary positioning machine (see the big leadscrew above the head? Our machine uses a big linear motor, and accellerates the head faster than this older machine.)
http://www.youtube.com/watch?v=oEz4L34ipYA
Now imagine our BIG chipshooter -- it has FOUR heads, that all work at the same time... :)
After the chipshooter is done placing, (and it places about 95% of the parts on the circuit board) the board moves into the flexible/fine pitch placer. This is a 7 spindle machine with vertical spindles instead of rotary spindles. It can pick and place a wider variety of parts than the chipshooter. So whatever the chipshooter can't handle is placed by the flexible/fine pitch placer.
This is similar to our flexible/fine pitch placer: Again, this is an older, slower machine than what we are using. We have one single head machine, and one dual head machine.
http://www.youtube.com/watch?v=wJ-vG8WcK7Y
Once the board is done in the flexible/fine pitch placer, it moves into the reflow oven, where the temperature is slowly increased as the circuit board moves through the oven, until the solder all melts at one time. Once it comes out of the oven, it gets queued for an AOI (automatic Optical Inspection) machine, where all the solder joints, joint quality, component placement, and component number and value are checked.
Then the boards are depanelized (cut apart -- we build anywhere from 20-120 circuit boards in a single panel) and queued for finish assembly, testing, and packaging.
That's pretty much how it's made.