The Analog Reader
Our first "fun" PCB is the Analog Reader. This board only has two SMD components on it, but if you don't have a stencil, it will be a bit tricky to solder.
Components and placement
For this board, you'll need:
| ID | Component | Description | Quantity |
|---|---|---|---|
| 1 | 7-pin JST-PH Connector | Connector towards the Main Board | 1 |
| 2 | 4-pin JST-PH Connector | Connector towards the Paw Board | 4 |
| 3 | 0805 100nF Capacitor | Decoupling capacitor for the chip | 1 |
| 4 | TSSOP-24 74HC4067 Chip | Analog multiplexer chip | 1 |
While placing the components, make sure that:
- The JST-PH & XT30 connectors are oriented correctly, with the connector centered inside the silkscreen markings on the PCB.
- The 74HC4067 chip is placed in the correct orientation, with the little notch on the chip towards the top (where the 7-pin JST-PH connector is).
Soldering the PCB
The SMD Components
All the components should be soldered following the Soldering Guide.
Make sure to apply the proper amount of solder paste to the pads, especially for the 74HC4067 chip, as it has a lot of pins and it's easy to create solder bridges if you apply too much solder.
The JST-PH Connectors
Place All the JST-PH connectors on the PCB, and flip the board over to solder the pins. This way, you can ensure that the connectors are properly aligned and flush with the PCB.
If you have some solder flux, apply it to the pins before soldering to improve the quality of the joints. Use a fine-tipped soldering iron and be careful not to apply too much heat, as the connectors can be sensitive to overheating.
For each connector, solder one pin first to hold it in place, then check the alignment and adjust if necessary before soldering the remaining pins.
Final inspection
After soldering all the components, inspect the PCB carefully to ensure that all joints are solid and there are no solder bridges or cold joints. Use a magnifying glass if necessary to check for any issues.
If you have a multimeter, you can also check for continuity between the pins of the connectors and the corresponding pads on the PCB to ensure that everything is properly connected.
In case you see a solder bridge between two pins, don't panic! Follow the Troubleshooting Section of the Soldering Guide to fix it.
This board is done? Well, let's move on to the next one then!