Hot Air Station Amateur Hour

A hot air station is one of the standard tools for working with surface-mount electronics, mostly in the context of rework to fix problems rather than initial assembly. In addition to manuals for individual pieces of equipment, there are guides like this one from Sparkfun. My projects haven’t really needed me to buy one, though that’s debatable whether that’s a cause or an effect: perhaps I design my projects so I don’t need one, because I don’t have one!

Either way I knew some level of dexterity and skill are required to use the tool well, and the best way to get started is to start playing with one in a non-critical environment. Shortly before the pandemic lockdown, I had the opportunity when Emily Velasco offered to bring her unit to one of our local meetups for me to play with. I had a large collection of circuit boards removed from tearing down various pieces of equipment. I decided to bring the mainboard from an Acer Aspire Switch 10, which was a small Windows 8 laptop/tablet convertible that I had received in an as-is nonfunctional state. I was able to get it up and running briefly but I think my power supply hack had provided the wrong voltage. Because a few months later, it no longer powered up.

Using the hot air rework station, I started with small SMD components. A few capacitors, transistors, things of that nature. I could take them off, and put them back on. I have no idea if they remained functional, that will be a future test at some point.

The USB ports and mini HDMI port on this device were surface mounted and I tried them next. I could remove them with the hot air rework station, but I couldn’t reinstall them. I got close so I believe this is a matter of practice and improving my technique.

Those connectors had relatively few large connection points, I tried my luck with larger chip packages on board. These were memory modules and flash storage modules, fairly large chips with electrical connections underneath where no soldering iron could reach them. My success rate here is similar, of being able to pull them off but not put them back on. I was less optimistic I could get this to work with practice, since these are ball grid array (BGA) modules and I would have to re-ball them to reinstall properly.

The largest chip on the board was the Intel CPU. I suspect there are heat dissipation measures in circuit board copper layers, similar to how a DRV8833 handles cooling with PowerPAD. Whatever is going on, I could not remove the CPU at all with this hot air rework station.

This was a fun introductory hot air play session, I look forward to more opportunities to learn how to use hot air once we can safely hold hacker meetups again. Here’s the final dissected cadaver:

Hot air rework session end

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