In the previous Monkeyprint board tutorial I showed you how to etch the PCB. In this follow up, you will be soldering the components to get your board going.
The procedure for soldering surface mount or through hole components is always the same. I will describe how I do it in the following paragraphs.
- Soldering iron.
- Solder. I use 0.5 mm SN62Pb36Cu2 with internal flux.
- Pointy tweezers.
- First, heat up the pad and/or the component.
- Then, and only then, apply the solder.
- Do not put the solder on the iron tip as the internal flux will evaporate before you manage to apply the solder to the pad.
- All soldering actions should only take some seconds.
To solder a component follow these steps.
Step 1: Surface mount components
Now that you know how to do the soldering, let’s find out what belongs where. There is a component placement guide in the Monkeyprint hardware folder:
Start by soldering the resistors and ceramic capacitors. They do not have a polarity, so as long as you follow the placement guide you will be fine.
For the 0 Ω resistors I use a piece of wire. Simply cut it off from one of the large through hole capacitors’ legs.
The small MosFET fits one way only. Make sure not to heat it up to long. As mentioned before, all soldering actions should only take some seconds.
Carry on with the large Schottky diode. This one — like all diodes — has a polarity, so make sure not to flip it. The white bar on the package is the negative side. Think of it as a big minus sign.
The Schottky diode is the last surface mount component to be soldered. Once you’re done with it, let’s carry on with the connectors.
Step 2: Solder the connectors
This is the easiest step. Simply follow these instructions:
Once all the connectors are soldered you can continue with the next step…
Step 3: Solder the remaining components
The rest of the components like the electrolyte capacitors is easy to solder. Simply stick the legs through the holes, hold the component firmly against the board and solder the pads.
The tricky part is the step down converter. It has to go onto the board in an upright position in order the fit the Raspberry Pi A+ footprint.
To mount the converter upright, cut two pairs of wire (diameter about 0.8 mm) to a length of 10 mm and 30 mm respectively. Solder the long ones to the (+) pads so that they are pointing into the non-populated side of the converter board. Then, solder the short wires the the (-) pads of the board so that they point to the populated side. Bend both pairs of wire down like shown in the pictures below. The converter board is now ready to be soldered onto the board.
Then, simply solder the converter onto the board. The populated side should point outwards.
Step 4: Solder the wire bridges
- Some insulated, flexible thin wire. I use 0.14 mm² wire. Black, red and another color would be nice but is not necessary.
- Some blank, stiff wire that I cut off from the larger through hole capacitors.
Connect the remaining pads following the component placement guide in the hardware folder.
Use red for 5 V, black for GND and another color for the other signals.
For short bridges use the stiff wire and bend a U-shaped connection.
There are holes in the wire bridge pads but I tend to solder them to the copper side just like surface mount components. This way you do not have to work your way around all the components on the top side.
Step 4: Pat your shoulder: Monkeyprint board almost done
You have almost completed the Monkeyprint board! In a follow-up tutorial I will show you the steps to connect your Monkeyprint board to all the other components like stepper motors, end switches and the Raspberry Pi.
If you like this or if you have questions or remarks, please comment below!
Good luck and happy soldering,