PCBA Factory Tour @ WAi

Yesterday Spencer and I drove to South Deerfield, MA and visited Worthington Assemblies - the printed circuit board assembly house who will be soldering together 2,500 circuit boards for the Public Radio over the next 6-8 weeks.  Chris Denny - the CTO - gave us a tour of the production floor, which was really awesome. It was the second time I'd visited an assembly house, and a lot of the workflow is still new to me so it was great seeing it first hand. 

The entire space is configured around the production line, parts and boards are received at one end and inspection and shipping is at the opposite side of the room with the pick and place machine, main conveyor, and oven in the middle.  

Everyone on the floor wears these blue anti-static vests, metal bracelets, and funny shoe straps to ground their bodies while handling electronics.  Additionally, the floor gets a coat of conductive wax once a month to allow any static voltages to pass through to the real ground. 


As WAi receives shipments from suppliers, a thermal printer spits out barcodes for reels of parts and panels of pcbs, which are then accounted for in an in-house inventory system and shelved until they're ready to be assembled. 

Next, parts get placed in a kit according to the number of boards they'll be assembling that day, and reels of components are loaded onto the feeders for the pick and place machine.  

Depending on the number of boards being assembled and the pitch and complexity of SMT footprints, a manual or automated solder paste machine is used to align the stencil and roll on a layer of solder.  The automated version is pretty neat, it aligns the pcb with the stencil using a camera, and is accurate to within 8 microns!  


WAi has two pick and place machines - one that they use for small runs and odd jobs, which is physically located off of the conveyor belt line, and another which is located just after the automated solder dispenser. 

Chris showed us the inside of one of them which has two main heads that pick and place the components using a fancy vacuum nozzle, and a set of claws which align the component to the center of the nozzle. There's also a secondary head which can grab and align six or so components at the same time.  


The last machine on the line is the oven, which is essentially a really, really fancy oven.  You input the weight and dimensions of the PCBs and it calculates the thermal mass to adjust the heating profile according to the solder being used.  There's a good video of Chris talking about it here.  

The rest of the floor is filled with carts of finished boards waiting to be tested and shipped out.  

All and all, a super interesting visit!