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SMT stage

Just one small part of the SMT floor

The SMT floor is filled with machines that autonomously handle most of the steps in this initial stage of production. The first of these machines is the solder paste printer, which prepares the traced PCB for component placement by spreading a thin layer of conductive solder onto the substrate through a stencil.

Solder paste printing

The next stop is the component gun, which places up to 10 components per second on each board in a dizzying display of mechanical engineering at its finest.

Check out the speed of the component gun

Components are loaded into the gun on reels, just like bullets in an ammo belt. Keep in mind that each of these resistors or microchips is only a few millimeters across; every reel pictured below contains thousands of parts.

The speed at which each reel spins gives you a good idea of how quickly components are placed

During the reflow soldering process, components placed by the rapid-fire gun are loosely soldered into place so basic testing can be done. If you want a good read on the details of this stage of the process, Wikipedia has a nice article on the subject.

Time for some inspections

After surface-mounted components are loosely anchored, it's time for the boards to be inspected. The first step of this process is done by hand, with a relatively small group of people performing a visual inspection of each board to ensure that nothing is obviously wrong.

These technicians took their time with each piece

Our tour guide explained that while automation in testing has come a very long way in this industry, there are certain things that humans are simply better at detecting quickly, like a burnt area of a PCB or a component that has been rotated slightly. For this reason, visual inspections are still an integral part of the assembly procedure. Certain machines are used in conjunction with these inspections to minimize defective boards, though.

This optical testing unit looks for problems with its own set of eyes

One of those machines is the optical tester, which takes many pictures of a board and uses specialized optical recognition software to analyze the photos for missing or improperly installed components.

It's short, but this little clip gives you an idea how the optical tester does its job

Instead of simply flagging boards as good or bad, the optical tester produces a detailed report of problem areas for a quick diagnosis.

One of the other automated board testers, this unit actually tests the components electrically

Large testing devices like the Miko-Kings TR-518FE check boards against a given template to ensure that each component is electrically connected.