Walk the assembly line and learn with Particle Co-Founder and CEO Zach Supalla as he covers the typical process for manufacturing hardware. This short video filmed on Zach’s recent visit to China covers the basics of a surface-mount technology (SMT) assembly line. From paste to final inspection, you’ll see the entire process.
As you’ll hear in the video, this particular line is getting ready to produce our new E Series LTE modules.
Pasting the PCBs
The process of manufacturing hardware beings in the solder paste machine. A printed circuit board (PCB) goes into the paste machine, and then a stencil is placed on top of it. This stencil ensures that paste only goes on the parts of the PCB where solder joints are necessary. Once paste is applied it is then spread with a squeegee-like device.
In the image above, you can see Will doing the manual version of that same solder paste process.
Picking and placing
[00:40] Once solder paste is applied to the PCB, the board is conveyed to a pick-and-place machine. The name says it all with this machine: it picks up minuscule surface-mount components (shown below) and precisely places them on the pads of the PCB that just received solder paste.
The assembly line in the video has multiple pick-and-place machines to accommodate the large number of components necessary for the PCB. The use of multiple machines varies from line to line and depends on the factory’s equipment capabilities and the complexity of PCB design.
Pick-and-place machines save an enormous amount of time. Trying to place an SMT component by hand is no easy task. Placing hundreds by hand is daunting. Above you can see how much concentration is required to place a tiny SMT component by hand.
[01:24] After the paste and components positioned on the board, the PCB is visually inspected to ensure that the pick-and-place machine put the tiny components where they need to be. Astonishingly, at this point in the process, the components are held in place by surface tension with the paste.
[01:30] Once the PCBs pass inspection, they are placed on a conveyor and run through a reflow oven. These machines are a bit like your conventional home oven, except they modulate their temperature based on the heat characteristics of the components and paste. Heating too quickly could damage the parts, but not supplying enough heat could result in bad solder joints.
Desktop reflow ovens like the one above can be great for small jobs. But production lines of designed to produce the E Series need much larger capacity than a desktop unit can provide.
After the PCBs exit the reflow oven, another round of visual inspection takes place. This review is to confirm that the solder joints (the connection between the PCB and the component created by heating solder paste) are solid.