Estimated reading time: 5 minutes
The following is a complete guide to making a simple PCB-based LED lamp project from scratch, covering all aspects such as selection, schematic design, PCB drawing, proofing, soldering, and testing.
Determine what your project needs are：
At the beginning of the design, you need to identify the core goals. First, think about how many LEDs there are and how they are arranged. Is it just one light, a few light strips, or a more complex display? The choice of power supply will impact the design. USB 5V is easy to connect. 12V works well for more LEDs in series.
If space is tight, you can choose battery power. If you want to create flashing or gradient effects, you need to use a microcontroller. This can be an ATtiny or an Arduino. Finally, determine the shape and size of the PCB to ensure that it meets the predetermined mechanical installation requirements.
Choosing the right device
Use a 3 mm or 5 mm round head high brightness LED. It should have a forward voltage drop of about 2 V for red or green. For white or blue, the drop should be about 3 V. You can also use a surface mount LED, like the 5050 SMD.
Current limiting resistor: Calculate based on the supply voltage.
If a 5 V power supply, white light LED (Vf≈3 V), target current 20 mA: R≈100 Ω.
Constant current driver (optional): such as AMC7135, a 350 mA low-power constant current IC, suitable for 1~3 LEDs in series.
MCU (optional): If you need flashing or breathing light effects, you can choose STM32F0, ATtiny13A, Arduino Nano, etc.
The following design schematic
Select EDA tools
KiCad (free and open source), Eagle, Altium Designer, etc.
Draw schematics
Connect by device: power → current limiting resistor → LED → ground.
If using MCU: MCU with Vcc, GND, IO port → current limiting → LED.
Create PCB layout
Add packages from component library to PCB.
Arrange LEDs reasonably, keep at least 2 mm spacing to ensure heat dissipation.
The width of the power line depends on the current demand: 0.2 mm can be used for 20 mA, and it can be appropriately widened if the current is large.
In most LED light designs, it is highly recommended to use connectors. They can simplify assembly and maintenance. A pluggable connector lets you easily connect or remove the LED module without soldering. This is helpful when you need to replace an LED or update firmware on an embedded controller.
Routing rules
Layer or partition the signal line and the power line to avoid interference.
Set the pad size in the solder paste layer.
Add vias and heat dissipation copper surfaces near the LED (such as high-power LEDs).
PCB file output and proofing
Configure the board thickness (1.6 mm), copper thickness (1 oz), solder mask color, and silk screen content in the manufacturing settings of the design software, and export the Gerber file. Upload the file through platforms such as Jinxinyang and place an order for a common FR4 double-layer PCB. The sample cycle is usually one to two weeks.
Component procurement and welding
Buy components: LED, resistor, microcontroller, etc.
SMD/Through-hole soldering
- Through-hole (3mm/5mm LED): solder one pin first, adjust the position, and then solder the other pin.
- SMD: You can use a soldering iron and solder paste, reflow soldering, or hot air soldering.
Check solder joints: Make sure there is no false soldering or short circuit.
Power on and functional test
Continuity test: first apply low voltage (such as USB 5 V) to test whether the LED lights up.
Measure current and voltage: make sure they are not exceeded to prevent the LED from overheating.
MCU program download (if any):
// ATtiny13A simple flashing example
#include <avr/io.h>
#include <util/delay.h>
int main(void) {
DDRB |= (1 << PB0); // PB0 is set as output
while (1) {
PORTB ^= (1 << PB0); // Flip PB0 pin level
_delay_ms(500);
}
}Debugging and optimization: adjust the flashing interval, current size, or add buttons, photosensitive controls, etc.
Shell design and heat dissipation solution
The shell is made according to the final application scenario. An acrylic or polycarbonate diffuser can be selected to improve light uniformity.
If the LED uses a lot of power, it is best to use a metal substrate. You can also add an aluminum heat sink to the backplane. Make sure to fix it with screws or thermal conductive glue.
Functional expansion
On this basis, the PWM capability of the MCU can be used to achieve breathing lights or color gradients. If you need wireless control, you can add a Bluetooth or Wi-Fi module.
Then, you can write firmware to let the mobile app control the lighting effect. In addition, after adding a photosensitive element, the system can automatically adjust the brightness according to the ambient light intensity.
Tools you may need: LED resistance calculator.
Through the above steps, you can complete a simple PCB LED light project alone. I hope this article can help you smoothly.
FAQ
This can result from miswired programming pins or missing reset pull-ups. Double-check your ISP/SWD header wiring and confirm VCC/GND levels. If your MCU requires a pull-up on the RESET line, add it (typically 10 kΩ). You can also test your programmer on a known-good breakout board to isolate the issue.
Shorts often come from solder bridges or a manufacturing defect. Inspect the board under bright, low-angle lighting to spot bridges. If the short continues, power the board with a current-limited supply. Then, check for a hot spot. You can also use solder wick to remove extra solder.
Overheating means you are driving them above their rated current or lacking proper heat dissipation. Increase the series resistor value or switch to a constant-current driver. For high-power LEDs, consider a metal-core PCB or attach small aluminum heat sinks directly beneath each LED.
