my own pick and place story - Page 1
Forum section: electronics / general

author: jmelson
author_rank: Super Contributor
timestamp: May 11, 2017, 02:05:00 am
content: In 2007, after about a year of watching eBay and talking to a lot of people on SMTNET, I fell into a deal on a Philips CSM84. I already knew from my research this was a pretty good machine for my uses. They guy had 2 new P&P machines coming in in 2 weeks, and had to get rid of the old ones, even if they "put them in the dumpster." Every day he'd call or email and the deal kept getting sweeter. First, just the machine, then the machine and some feeders, then machine plus all the feeders he had, then the mechanical alignment station and a vibratory feeder base, and finally he threw in the guts of the other machine that he was scrapping.So, that cost me $3300, I think, plus shipping. I had about 2 weeks notice to get a doorway big enough to accept the machine into my home BASEMENT. Seehttp://pico-systems.com/CSM84.htmlfor some pics. The CSM84 is 5' x 7' and weighs about 1700 Lbs. It actually cost me more to have the double doors put in than I paid for the machine.This machine does not have the vision option. But, many of the CSMs of that vintage that were on the market had non-working vision boards.The CSM84 is old-school, with mechanical alignment chuck jaws that center the part when the nozzle comes all the way up. I took the jaws off the 3rd head, made a big nozzle with lathe and mill, and use that one for FPGAs and other large chips, with the mechanical aligner.I think they guys that sold me the machine really didn't know what they were doing, the rear feeder and mechanical alignment station offsets were zero, so they couldn't use them.Anyway, within 2 weeks of getting the machine, I was in full production with it. Without vision, programming it is pretty easy. There is a feeder file that holds what is at every feeder position, and tells what size feeder is there, how many pokes to trip the feeder advance lever, what rotation to pick up the part in, how much vacuum is OK, how many times to retry a mis-pick, etc. It also has much more complex fields for tray feeders and such. Although you can generate this file via a program, I generally just edit it on the machine, and then save to a PC.The placement file has some info for board coordinates, location, size and spot vs. hole for fiducials, bad mark, and then one line per part.The part lines are feeder #, X, Y rotation and head to use, and a skip field. I wrote a c program that takes in a component definition file and the P&P file from my CAD package and puts out this file. The component file also tells which head to use, and what the component's rotation in the part tape is vs. how the CAD package defines it, so that the rotation given the machine is correct.I don't know how many boards I've done with it, but it is several thousand.The smallest stuff I do is 0603 passives. I got a board designed by somebody else, and it was all 0603. I had fits with mis-picks. The guy who sold me the machine also gave me a homemade feeder stand which was quite useful when loading feeders. I added a bridge that snaps in over the feeder with a window with crosshairs to view the location of the component pocket. Well, they were all over the place! So, I aligned the crosshairs to the feeder that worked best for the 0603 parts, and then adjusted all the other feeders as close to that one as possible. 0603 parts feed fine now. The only problem was 0603 LEDs, which have a much smaller flat top than the part body. I ended up changing over to use 0805 LEDs, and these fit the board pads just fine, and feed reliably.As for soldering, I use a GE toaster oven with a thermocouple ramp and soak controller from eBay. My first batch were totally fried, the boards absorbed IR was faster than the thermocouple. So, I poked the thermocouple into a PTH in the board, and it worked like a charm!I do mostly lead free with SAC305 solder, but do some PbSn soldering for nuclear instruments. I have done boards as big as 8 x 11" in the oven.I make my own solder stencils. Some years ago I built a laser photoplotter for making PC board artwork. I rarely use my PCB manufacturing gear anymore, as I can get MUCH better boards made so cheaply now. But, a stencil is kind of like a PC board without the fiberglass. So, I make 2 mirror-image artworks on the photoplotter from the CAD/CAM solder stencil Gerber file, and laminate dry-file PCB resist to a piece of .003" brass shim stock, and process it just like a PC board. This makes a great stencil for limited runs. I've used these stencils for up to 300 boards each, and they still look good.Jon