Summary
This video demonstrates how to copy an existing circuit board design by converting a PCB image into an editable schematic within Inkscape. The process involves importing the image, tracing it to create vector paths, cleaning up the traces, scaling them to correct dimensions, and exporting as an SVG. This SVG is then imported into KiCad's footprint editor to create a custom component that can be placed on a new PCB layout, allowing for the replication of circuit designs without redrawing schematics and facilitating efficient board manufacturing.
Key Insights
Scale the traced design to the correct physical dimensions.
Use the measure tool in Inkscape to check the actual dimensions of the traced elements. Hold 'Control' while resizing the selected paths with the handles to ensure uniform scaling. Iterate resizing and measuring until the dimensions match the required physical specifications, preventing wasted time in subsequent steps.
Perform a Design for Manufacturing (DFM) check using the fabrication toolkit.
The fabrication toolkit also includes a DFM check. This analysis verifies if the design meets manufacturing standards for various aspects like trace width and spacing, providing confidence in the manufacturability of the board.
The SVG-to-footprint method allows for efficient circuit replication.
By converting a PCB image to an SVG and then into a KiCad footprint, existing circuit designs can be accurately replicated without the need to manually redraw schematics, saving significant time and effort in the design process.
Sections
Importing and Tracing PCB Image in Inkscape
Start a new Inkscape project and import the PCB image.
Open Inkscape, go to 'File' > 'Import', and select the prepared PCB image. Move the image onto the canvas and then adjust the canvas size to fit the image using 'Document Properties'.
Use 'Trace Bitmap' to convert the image into editable paths.
Right-click the imported image and select 'Trace Bitmap'. Adjust the threshold to determine which parts of the image are converted into polygons. Apply the trace to create vector paths based on the image's black and white areas, aiming for a balance that captures details without excessive noise or loss.
Clean up the traced paths by deleting unwanted elements.
After tracing, clean up the resulting paths. This includes deleting extraneous elements like drill holes that were accidentally traced, or correcting overlaps and errors in the generated polygons by manually editing nodes and segments.
Manually redraw intricate or imperfect traced sections using the Pen Tool.
For areas that were not traced well or require specific shapes, use the Pen Tool. Click to create sharp corners or click and drag to create smooth, continuous curves with adjustable handles. This allows for precise manual tracing of any desired shape.
Verify the traced design by toggling path visibility.
Toggle the visibility of the traced paths to confirm that the cleanup and manual redraws have produced the desired result and that the paths accurately represent the original circuit features.
Scale the traced design to the correct physical dimensions.
Use the measure tool in Inkscape to check the actual dimensions of the traced elements. Hold 'Control' while resizing the selected paths with the handles to ensure uniform scaling. Iterate resizing and measuring until the dimensions match the required physical specifications, preventing wasted time in subsequent steps.
Export the cleaned and scaled design as a plain SVG file.
Select the final traced and scaled paths. Go to 'File' > 'Export'. Choose 'Selection' and export as a 'Plain SVG', saving it to a desired location. Ensure the export format is suitable for importing into PCB design software.
Creating a Custom Footprint in KiCad
Create a new project and open the PCB editor in KiCad.
Start KiCad, create a new project, and then open the PCB editor. Navigate to the Footprint Editor from within the PCB editor to begin creating a new component based on the exported SVG.
Create a new library and footprint for the custom trace design.
In the Footprint Editor, create a new library (e.g., 'custom') and save a new footprint within it (e.g., 'traces'). This organizes the custom component for future use.
Import the SVG file into the footprint editor on the desired copper layer.
Go to 'File' > 'Import' > 'Graphics' and select the exported SVG file. Choose the appropriate layer, typically the 'F.Cu' (Front Copper) layer, for the trace import. Place the imported graphics onto the footprint canvas.
Add pads and vias to the footprint, defining their properties.
Use the pad tool to add connection points. Configure pads as circular, specifying the hole diameter and the overall pad diameter (including solder mask). Place pads at the ends of the imported traces. Add vias if necessary, also defining their size and hole diameter.
Align and arrange pads and vias for the component.
Utilize alignment tools to position pads and vias correctly. For instance, select multiple pads and align them vertically or horizontally. This ensures precise placement for electrical connections.
Assign nets to footprint pads for connectivity in the schematic.
If the imported design needs to connect to specific nets, open the Netlist Inspector. Add a new net (e.g., 'middle') and assign it to the relevant pads and through-holes within the footprint properties. This allows the component to be correctly wired in the PCB layout.
Save the custom footprint to the created library.
After placing all elements and defining properties, save the custom footprint to the established library. This makes the component available for use in PCB projects.
Integrating and Finalizing the PCB Design
Place the custom footprint onto the PCB layout.
Return to the main PCB editor and place the newly created custom footprint containing the copied traces from the library into the project. This component can then be treated like any other standard component.
Add board outline and other necessary manufacturing elements.
Define the board's outline on the 'Edge.Cuts' layer using drawing tools like rectangles. This step is crucial for defining the physical boundaries of the PCB for fabrication.
Utilize the JLC-PCBCalculator plugin for production file generation.
Install and use the 'JLCPCB Fabrication Toolkit' plugin. This tool, found under 'Tools' > 'External Plugins', can automatically generate all necessary production files (like Gerber and Drill files) in a format suitable for PCB manufacturers.
Perform a Design for Manufacturing (DFM) check using the fabrication toolkit.
The fabrication toolkit also includes a DFM check. This analysis verifies if the design meets manufacturing standards for various aspects like trace width and spacing, providing confidence in the manufacturability of the board.
The SVG-to-footprint method allows for efficient circuit replication.
By converting a PCB image to an SVG and then into a KiCad footprint, existing circuit designs can be accurately replicated without the need to manually redraw schematics, saving significant time and effort in the design process.
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