Socketing your microcontroller has several benefits, which you can read at Why would I want to socket my microcontroller? In this short guide I'll teach you how to socket your microcontroller. The steps in this guide use a Minidox kit as an example, but the steps will be the same on any keyboard that uses a Pro Micro, Elite C, Proton C or similar controller.
Installing sockets has the following steps:
Take a break! Many people run into issues at this step, so read over the instructions entirely before soldering, and make sure you place the controller on the correct side of the PCB with the controller facing the correct way. Of all the components in a keyboard build, the microcontroller is the most difficult to desolder if you make a mistake. Soldering it on won't be difficult if you follow the steps right, just take your time.
If you're using the Mill Max Low Profile Sockets with pins, you may skip ahead to Installing the sockets.
Gather the diode legs
First, when installing the diodes, you should clip off the diode legs and save them for this step. You'll use these diode legs later since they fit perfectly into the sockets.
Installing the sockets
Now we're ready to socket the microcontroller. You'll need your controller, a pair of sockets, diode legs and some tape.
Using the tape, fix the sockets to the PCB temporarily. This makes installing the sockets much easier.
Where you place the sockets matters. On splitkb.com keyboards, you need to place the sockets within the white outline, and this means that you'll be soldering on the other side of the keyboard, where the solder joints are not in a white outline. Please take the time to refer to the build guide of your keyboard to see more information on controller placement, getting this right will save you a lot of time and headaches.
Solder one of the socket pins first. Flip over the PCB and check if the socket sits flush with the PCB. If not, you can reheat the pin and realign the socket. Then, once you're happy with the alignment, solder the remainder of the socket pins.
Seating the legs
With the sockets installed, it's now time to insert the legs into the sockets.
You can choose to apply some tape over the sockets before inserting the legs. This makes the insertion of the legs more difficult, but will prevent solder from leaking into the sockets, which makes removal later on harder. In this example, I used simple scotch tape, but if you have Kapton or other heat resistant tape, it will be better suited to the purpose.
When you're using diode legs, insert two of the diode legs into the sockets, one in each socket. Slide over the microcontroller, taking care of the orientation. Then, insert the rest of the diode legs. You'll feel a sort of "click" when inserting the legs, which signals that it's inserted correctly.
When you're using Mill Max socket pins, first insert all of the pins using pliers. They'll "click" into place. All the pins should be inserted the same depth, so when you look at the socket from the side and see one or more pins sit higher than the rest, use pliers to push them down. You shouldn't need to force this, but you should feel the legs click into place.
Take care of the microcontroller orientation. On some boards, the Pro Micro will face up, on others, it will face down. The build guide for your keyboard will note which side the Pro Micro should face. Some PCBs will have pin markings next to the sockets: these should match up with the pin markings of your Pro Micro. For example, on the Kyria, both microcontrollers will face with their USB jack down.
When inserting the diodes into the sockets, please consider using pliers. The socket legs can be very sharp and you may pierce the skin of your finger accidentally. Pliers allow you to maintain a better grip and a safe distance from the sharp pins.
Clipping the legs
After soldering the legs, you can cut off the excess length using flush cutters.
If you've used Mill Max pins, you don't need to do any clipping.
When trimming the legs, take care to wear eye protection. I prefer to wear a protective working glove, and place my hand close above the cutting area to prevent tiny sharp bits of metal from flying around. The glove will keep my hand from being hit by the pieces. They can be quite sharp!
If you used tape between the controller and the sockets, you can carefully place your pliers between the controller and the PCB, and wedge up the controller slowly but surely. Take care not to damage other components by doing this: the glass diodes can be rather fragile. When removed, you can remove the tape, bend straight any bent legs with the pliers, and carefully insert the microcontroller again.
Congratulations! You've socketed your microcontroller. If you have a split keyboard with two controllers, you'll need to do this once more for the other side. Continue with the build guide for your keyboard to finish the build.