Dot Matrix Business Card

Step 3 Soldering Starts!

Solder the components onto the board, starting with the smallest first (Refer to photos). A pair of tweezers is useful here - by putting a blob of solder on a pad, and then re-melting it whilst positioning the resistors or capacitors with the tweezers, you can neatly add these small components. It doesn't matter which way around these components go, but it does for the PIC (which should read with the writing the correct way up as shown in these photos), and also the LEDs must be put around the right way. It is harder to tell with the LEDs which way around they should go - the top connection should be the positive (or "anode"). You can tell by consulting the datasheet for the LED - one of the two leads will usually be marked in some way. An easier way is sometimes to test one of them by attaching a couple of wires to a small 1.5V battery, and then touching the leads on the ends of the LEDs - if it is the right way around, you should see a glow, but if using a single 1.5V battery, it will be extremely faint, so you will have to observe carefully. Again, a tutorial on soldering is not within the scope of this article - I did warn you that this isn't a beginner's project, so don't make this one your first venture into surface mount soldering! Note that the LEDs are only initially soldered on their bottom lead - we will use some wires later to connect their top leads.