I always had this impression that almost everything was made by a machine. Of course, the tours of the textile factories corrected my impression of that very quickly, but still, high-tech stuff like electronics assembly tends to be heavily automated even in China. The only exceptions were, ironically, in the lowest cost sectors, such as toys. These shops are still dominated by lines of workers still stuffing and dip-soldering circuit boards by hand.
On the topic of toy factories, one interesting dichotomy to me is the bimodal distribution of products that use chip-on-board (CoB) technology. CoB assembly directly bonds a silicon die to a PCB. Finished CoB assemblies have the distinctive “glob of epoxy” look to them, as opposed to the finished plastic package look.
At the high end of things, dense electronics assemblies will employ CoB technologies. I’ve done a couple of CoB designs for some 10 Gb optical transceivers in my time, and they were not cheap. At the other end of things, almost all toys use CoB technology, to save the cost of the package! It’s a testament to the tenacity of the cost reduction in China that a toy factory would buy an automated wirebonder and stick it next to lines molding doll heads and sewing up stuffed animals because it saves that nickel.
For those who are not familiar with wirebonders, a typical bonder takes a wire as thin as a human hair and bonds it to a site on a silicon chip not much larger than the wire diameter, and it does this several times a second. It’s a very fast, precise piece of equipment, as you can see below. The bonding happens so quickly that the board seems to swivel smoothly around in the video, but in fact the board stops 16 times as it spins around, each time getting a wire bonded between the chip and the board.
Immediately before bonding, the chip is glued very carefully to the board by hand, and immediately after bonding, the chip is encapsulated by an operator dispensing epoxy very carefully by hand–so this is the only automated piece of equipment on the line. Gives me a new sense for what goes into those talking Barney dolls that sell for $10 in Target.
Back to the general topic of automation. I think it’s absolutely mesmerizing to see a chip shooter in action. The chumby PCB assembly factory in China has dozens of lines filled with tried and true Fuji chip shooters.
The chip shooters are capable of placing something on the order of 10,000-20,000 components per hour per machine. This means that each machine can put down about 3-6 components per second–the robotic assemblies move faster than the eye can see, and it all turns into an awe-inspiring blur. In the video below, you can see the chip shooter in action. It has a “gatling gun” style action. The gun itself is fixed, and the board dances around beneath the gun. The chip shooter actually “looks at” each chip and rotates it to the correct orientation before putting it down on the board. I wish bandwidth were a bit cheaper so I could encode this video at a rate where you can really see all the detail going on here.
Chip shooters do the fast and furious work of putting down the simpler components, such as capacitors, which are quite numerous in a typical design. For the more complex/expensive devices that demand a greater precision of placement, a pick and place machine is used. Instead of a gatling-gun style head, a pair of robotic arms with pneumatic plungers pick components out of their trays and very accurately places them on the PCB.
The particular factory shown here also produces name-brand PC motherboards, and they seem to have no problem pushing out well over 10,000 such complex assemblies each day.
The end of the line for this chumby core board assembly….