Electronics Production

Goals

group assignment

• characterize the design rules for your in-house PCB production process
• submit a PCB design to a board house

Individual Assignment

• make and test a microcontroller development board that you designed
• extra credit: make it with another process

Group Assignment

Design Rules for in-house PCB production process

Machines and Tools

The equipment used in Litchee’s studio for PCB fabrication is the Snapmaker.
Official website: https://www.snapmaker.cn/

Snapmaker is a versatile 3-in-1 desktop manufacturing tool that integrates 3D printing, laser engraving, and CNC carving in one machine. With its sleek design and intuitive operation, it is ideal for makers, designers, educators, and labs. Its innovative modular design allows users to easily switch between different work modules to meet a wide range of creative needs.

Key Features

3D Printing Function:

• Supports FDM (Fused Deposition Modeling) technology, capable of printing with various plastic materials such as PLA, ABS, and TPU.
• High printing precision, suitable for producing small, accurate models, prototypes, and complex designs.
• Equipped with an automatic bed leveling function to ensure accurate prints every time.

Laser Engraving Function:

• Supports high-precision laser engraving on wood, leather, plastic, and other materials.
• Adjustable laser power to accommodate different materials and engraving depths.
• Fine laser control system enables detailed engraving, ideal for artistic work, personalized designs, and creative gifts.

CNC Carving Function:

• Supports computer numerical control (CNC) carving for materials like wood, plastic, and aluminum.
• High-precision cutting capability suitable for delicate craftwork or small-batch production.
• Equipped with a powerful drive system, capable of handling complex engraving tasks.

Snapmaker Product Specifications

Basic Parameters

• Machine Size: 335 × 272 × 289 mm
• Net Weight: 5.7 kg
• Body Material: Aluminum Alloy
• File Transfer: USB Drive, USB Cable
• Power Input: 100–240 VAC
• Operating System: macOS, Windows
• Touchscreen: 3.5 inch

3D Printing

• Heated Bed Temperature: Up to 80°C
• Build Volume: 125 × 125 × 125 mm
• Head Movement Speed: Up to 100 mm/s
• Nozzle Diameter: 0.4 mm
• Nozzle Temperature: Up to 250°C
• Layer Thickness: 0.05 – 0.3 mm
• Supported Materials: 1.75 mm PLA, ABS, etc.
• Unsupported Materials: Nylon with aluminum powder, graphite, etc.
• Supported File Types: STL, OBJ
• Software: Snapmakerjs, Cura, Simplify 3D, Slic3r, etc.

Laser Engraving

• Working Area: 125 × 125 mm
• Laser Power: 200 mW
• Laser Wavelength: 405 nm
• Laser Safety Class: Class 3B
• Supported File Types: SVG, JPEG, PNG, etc.
• Supported Materials: Wood, bamboo, leather, plastic, paper, fabric, non-transparent acrylic, etc.
• Unsupported Materials: Metal, glass, gemstones, transparent or reflective materials
• Software: Snapmakerjs

CNC Carving / Cutting

• Working Area: 90 × 90 × 50 mm
• Tool Shank Diameter: 3.175 mm
• Supported Materials: Wood, acrylic, PCB, carbon fiber board
• Unsupported Materials: Metal, glass, gemstones, etc.
• Spindle Speed: 19,000 RPM
• Supported File Types: SVG, STEP, IGES, IGS, DWG, DXF
• Software: Snapmakerjs, Autodesk Fusion 360, ArtCAM, etc.

*Note: Users can use third-party software such as Autodesk Fusion 360 to convert supported file formats.

Snapmaker PCB Milling Process

As a 3-in-1 desktop manufacturing tool, Snapmaker integrates 3D printing, laser engraving, and CNC carving. Beyond its standard features, Snapmaker can also be used to mill PCBs (Printed Circuit Boards) using the CNC module. The machine provides high precision for operations such as trace isolation and drilling. Below are the steps and principles for milling PCBs with Snapmaker:

Steps to Mill a PCB with Snapmaker

1. Prepare the PCB Design Files:

• Use PCB design software (such as KiCad or Eagle) to create your circuit and export the Gerber files.
• Make sure the files include traces, component placements, and drill holes.

2. Install the CNC Module:

• Attach the CNC carving module to the Snapmaker machine.
• Use a suitable tool head, such as a fine engraving bit or micro drill.
• Adjust the module height to ensure the bit can precisely contact the PCB surface.

3. Secure the PCB:

• Use Snapmaker’s built-in clamps or custom fixtures to hold the PCB in place.
• Ensure the board is flat and stable to avoid any shift during milling.

4. Choose the Right Bits and Tools:

• Select the appropriate tools based on your Gerber files.
• Use fine bits for trace isolation and drill bits for hole making.

5. Set the Machining Parameters:

• Download and install the control software Snapmaker Luban: Download here
• In the software, set parameters such as feed rate, cutting depth, and tool path.
• Adjust settings according to the PCB material and desired precision.

6. Start CNC Milling:

• Load the Gerber files into Luban and start the job.
• Snapmaker will automatically execute the engraving and drilling tasks according to the design.
• It will accurately remove unwanted copper and leave behind the desired circuit paths.

7. Post-processing and Cleaning:

• Inspect the final PCB for clean traces and accurate drill holes.
• Use a brush to remove any remaining debris from the board.

Producing PCB at PCB-house

In the previous week 6 assignment, I created the schematic in JLCPCB EDA.

Introduction to JLCPCB:

JLCPCB (JLC Electronics) is a company that provides one-stop infrastructure services for the electronics industry, headquartered in Shenzhen. Since its establishment in 2006, JLCPCB has been committed to providing cost-effective PCB prototyping, small batch production, SMT assembly, laser stencil, FA mechanical parts, and other services to electronic engineers, research institutions, and enterprises around the world.

Therefore, I can directly open the already saved PCB files in my account and place an order.

Go to the "Order" menu at the top and select "PCB Order" to proceed.

After clicking, the Gerber files, coordinate files, and BOM list will be automatically generated.

JLCPCB allows online ordering. You only need to confirm the board specifications, which is very convenient.

I chose FR-4 as the board material, and selected the default quantity of 5 pieces, which is free.

The solder mask layer I designed in week 6 is black, with gold-plated pads.

I kept all other settings as default. Finally, I selected the delivery time. Black solder mask takes a little longer, and production can be completed in 3 days.

The delivery is also free!!!!

Finally check the order information and it can be submitted.

Individual Assignment

I exported the Gerber file in JLCPCB EDA.

Before exporting, it will prompt to check DRC.

It is exported as a compressed file package.

I used Gerber2PNG to generate PNG images from the PCB file.
Website: https://gerber2png.fablabkerala.in/

After opening it, I found some problems. The PCB layout I drew in JLCPCB EDA is a two-layer board.

I sent the PCB layout to my friends for review. They pointed out that this part had copper fill, which would require wire-jumping (flywires), and that it needed to be made as a two-layer board. Then, the two layers would need to be combined into one.

Considering that my ability to fabricate a double-layer board is limited and the failure rate would be high, I decided to modify the layout.

I redrew the layout as a single-layer board and kept only the extended part. Below is the modified schematic:
Schematic file:

Download

I opened the new design file with Gerber2PNG, and everything looks perfect!

I exported the cutout and drilling images.

Since the CNC machine I was using this week broke down, I decided to try one of the most traditional methods—chemical etching—to make my own PCB. Although this process is more cumbersome than mechanical machining and involves chemical handling, the overall experience was rewarding and helped me better understand the fundamental principles of PCB formation.

What is the etching method?
The etching method is a technique that removes excess copper from a copper-clad board using an etching solution. Simply put, it involves protecting the parts of the circuit you want to keep (for example, using toner or oil-based ink), and then using the etching solution to "bite away" the unwanted copper. In the end, only the conductive traces of the circuit pattern remain.

Materials and Tools Used

Item	Description
Single-sided copper-clad board	Common phenolic board or fiberglass board
Laser printer	Used to print the circuit pattern (inkjet printers do not work)
Glossy paper / transfer paper	Used for transferring the pattern (I used magazine paper)
Iron / laminator	Used to heat-transfer the pattern
Ferric chloride (FeCl₃)	Commonly used etching solution
Plastic container	For holding the etching solution (metal containers are not allowed)
Gloves, mask	Basic protection during chemical handling
Alcohol / nail polish remover	For cleaning the board and removing toner
Electric drill / manual drilling tool	For drilling component holes

Detailed Production Steps

Detailed Production Steps

1. I exported the PCB layout as a mirrored image, because the heat transfer process is reversed.

2. Surface Cleaning
   I gently sanded the surface of the copper-clad board with fine sandpaper to remove the oxidation layer. Then I wiped it clean with alcohol to ensure it was free of oil and dust.
3. Pattern Transfer
   I placed the printed pattern tightly against the copper board, soaked it in water for a few minutes, and then carefully peeled off the paper. The toner pattern remained on the board.
   For any areas that didn’t transfer well, I manually filled them in with a black oil-based marker.

4. PCB Etching
   I poured ferric chloride solution into a plastic container, warmed it slightly, and placed the board inside. I gently shook the container to help the etching proceed evenly. After about 20 minutes, the exposed copper was completely etched away, leaving only the desired pattern.
   ⚠️ I wore gloves and a mask throughout the process and worked in a well-ventilated area to ensure safety.

#define XIAO_ESP32S3_D1 
                #define LED_PIN 3  // Connected to D2
                
                void setup() {
                  pinMode(LED_PIN, OUTPUT);
                  digitalWrite(LED_PIN, HIGH);  // Turn on the LED
                }
                
                void loop() {
                  digitalWrite(LED_PIN, HIGH);
                  delay(500);
                  digitalWrite(LED_PIN, LOW);
                  delay(500);
                }