LED Flower
PCB
BOM
Necessary
| Designator | Value | Part-No | Price / EUR | Count | Sum / EUR |
|---|---|---|---|---|---|
| R1 | 3.6 kΩ, 1206 | R: | 0.01 | 1 | 0.01 |
| R2 | 2.7 kΩ, 1206 | R: | 0.01 | 1 | 0.01 |
| R3, R4 | 68 Ω, 1%, 1206 | CSD: 10-120068 | 0.01 | 2 | 0.02 |
| R5..R19, R38..R40 | 3.6 kΩ, 1206 | R: | 0.01 | 18 | 0.18 |
| R20..R31 | 100 Ω, 1206 | R: | 0.01 | 12 | 0.12 |
| R32..R37 | 150 Ω, 1206 | R: | 0.01 | 6 | 0.06 |
| B1..B3 | 0 Ω, 1206 | R: | 0.01 | 3 | 0.03 |
| T1..T18 | BC807-25, SOT23 | R: BC 807-25 SMD | 0.04 | 18 | 0.72 |
| C1, C2, C3 | 100 nF, 16 V, 0603 | R: X7R-G0603 100N | 0.05 | 3 | 0.15 |
| C4, C5 | 22 pF, 0603 | R: NPO-G0603 22P | 0.05 | 2 | 0.10 |
| C6 | 10 uF, 10 V, 0805 | R: X5R-G0805 10/16 | 0.07 | 1 | 0.07 |
| C9 | 100 nF, 63 V, 1206 | R: X7R-G1206 100N | 0.05 | 1 | 0.05 |
| D2, D3 | 3.6 V Zener Diode, MiniMELF | R: SMD ZF 3,6 | 0.05 | 2 | 0.10 |
| X1 | 20 MHz | R: 20,0000-HC49U-S | 0.18 | 1 | 0.18 |
| ISP, ADC, PWR | 12-pin break-away connector (from a 36-pin strip) | R: SL 1X36W 2,54 | 0.27 | 1 | 0.27 |
| CONN_USB | USB B connector | R: USB BW | 0.21 | 1 | 0.21 |
| U1 | ATmega88-20AU | R: ATMEGA 88-20 AU | 2.95 | 1 | 2.95 |
| LED1..LED6 | RGB LED | ? | 0.30 | 6 | 1.80 |
| 24 Copper wires | 40 cm copper wire cutoff | R: CUL 500/0,63 | 13.90 | 0.058 | 0.81 |
| Sum | 7.84 | ||||
Version 1: USB Powered
| Designator | Value | Part-No | Price / EUR | Count | Sum / EUR |
|---|---|---|---|---|---|
| L1 | 10 uH, 450 mA, 1210 | CSD: 146-121R010 | 0.22 | 1 | 0.22 |
| U2, C7, C8 | Do not populate | 0.00 | 0 | 0.00 | |
| Sum | 0.22 | ||||
Version 2: Externally powered
| Designator | Value | Part-No | Price / EUR | Count | Sum / EUR |
|---|---|---|---|---|---|
| U2 | LM1117-5.0 | CSD: LM1117DT-5,0V | 0.95 | 1 | 0.95 |
| C7, C8 | 10 uF, 10 V, 0805 | R: X5R-G0805 10/16 | 0.07 | 3 | 0.21 |
| D1 | 1N4001, MELF | R: X7R-G1206 100N | 0.04 | 1 | 0.04 |
| L1 | Do not populate | 0.00 | 0 | 0.00 | |
| Sum | 1.20 | ||||
Option: Button
| Designator | Value | Part-No | Price / EUR | Count | Sum / EUR |
|---|---|---|---|---|---|
| R41 | 3.6 kΩ, 1206 | R: | 0.01 | 1 | 0.01 |
| BTN | Pushbutton | ? | 0.10 | 1 | 0.10 |
| Sum | 0.11 | ||||
Tutorial
Microcontroller
The first step in soldering this board is also the most difficult: Soldering the microcontroller. We are going to use the drag soldering technique. To do so, we first place the microcontroller on the board to get an idea of how it should be placed afterwards. Note the pin one mark which is a small dip in one corner of the IC. This is used to orient it correctly:
Now remove the microcontroller again, select one pad of the pcb and tin it. For this and the next two steps, you don't have to worry about any solder bridges, we will remove them afterwards.
Now grab the microcontroller with a pair of tweezers, heat up the tinned pad and place the microcontroller correctly. Do not overheat the microcontroller: If you are not able to position the microcontroller within about 10 seconds remove the soldering iron and try again after waiting a short amount of time.
To further secure it, also solder one pin on the opposite corner.
Now select one edge of the microcontroller that has not been used in the previous steps and add some Flux to pins. What comes now is not easy and probably may require multiple attempts: Solder some pins one on side of the edge at once and then just slide the soldering iron slowly and without any pressure to the other side:
If you have done everything right (right speed, correct amound of solder and flux) all pins will be soldered to the board and there will be no bridges between them:
If you have created any bridges, there are two ways to get rid of them:
- Drag the solder away from the microcontroller.
- Use a desoldering gun or desoldering wig.
However, repeat this process for the three other edges that are not yet soldered completely:
Decoupling Capacitors
To operate, the microcontroller needs a set of decoupling capacitors. These are two-padded components, so we will esentially replicate the first steps of the microcontroller soldering process:
- Tin one pad,
- add the component and
- solder the other side.
This it what it looks like for C?:
