This technique explores using a fitted 3D printed mold as a guide for laying out and trimming copper tape traces by hand to make a quick PCB-style circuit.
My 3018 CNC machine had been giving me trouble. Auto leveling was off, and the copper boards were a little bit smaller than I needed, so I decided to explore an alternative method using a 3D printed mold.
I used my KiCAT design which was a quick project I did after seeing Quentin's Qpad. Learn more about KiCAT here.
Reflection: Choose a fun filament color that doesn't clash with your copper tape. Soldering may require some skills and experience. Use flux well for quick and clean soldering.
I needed to check the 3D printed trace guides to ensure an easy making process. I looked at how copper tape behaves around corners, how much spacing is needed between traces, and how high the printed guide needs to be in order to support easy hand cutting.
Key things I tested and observed:
The main design constraint is balancing precision with ease of assembly. If the mold is too tight, it doesn't give enough room for the tape which can lead to tearing or misalignment, and if it is too loose, the guides can't be as effective and precise.
I tested different mold heights to determine the optimal guide thickness for clean copper tape cutting. Here are the height variations tested:
Observation: At 0.4mm, the guide is very subtle and minimal. This height was a little difficult to cut because it was too low to provide adequate tactile feedback with the blade.
Observation: At 0.6mm, the guide provides moderate height for better handling and alignment. Copper tape adheres well and can be cut cleanly against this edge. This one proved to work well with or without the trace guide.
Observation: At 1.2mm, the guide is tall enough for strong tactile control and provides excellent cutting guidance. The increased height offers better blade support during cutting operations. However, it was too tall for some delicate maneuvers and some traces busted or broke when used with trace guides.
Conclusion: The 0.6mm trace height tested the best balance between printing efficiency and cutting guidance. Heights below 0.4mm made cutting guide not so clear, while anything over 1 mm becomes unnecessarily bulky and difficult to use with the delicate copper tape.
I exported my KiCAD pcb design as SVG files and had to use a 2D tool to convert them into DXF format for Fusion 360. That was an annoying extra step, I might have to try and look for a more direct workflow in the future.
I set up parameters in Fusion 360 so I could quickly change trace height and spacing during testing. I also added small bridges on the trace guide to support thin sections that were prone to bending or breaking as we can cut the parts that were skipped due to the bridge after releasing the mold.
For the offset for the trace guide I tried 0.4mm so that the blade can accurately follow the intended path, but I found out that it was not super necessary as we can just follow the edge of the guide directly. so I set the offset as 0.2mm since the copper tape is supposed to be 0.05mm thick.
WooHoo! Designing with Fusion and Parameter setup was tested and easy for me, but I was not satisfied with the entire design to print process. I tried creating an app to make my PCB design PNG files into 3D file. It is still in early development and needs more testing, but seems to be worth a try. Link is in the sidebar.
I might also try making something for Mods
Core items used in this technique study:
| Item # | Item | Purpose | Notes | Format | Status |
|---|---|---|---|---|---|
| 1 | Copper tape | Conductive traces | Needs to be as big as your PCB and have a strong adhesive backing | Roll cut to correct size | Used |
| 2 | 3D printed top | Trace outline guide | Sized to fit the back surface accurately and have the trace paths clean with no failed print | Printed part | Used |
| 3 | 3D printed bottom | PCB substitute surface with trace | Needs to have 0.6mm trace height and at least 1.6mm thickness overall for stability | Printed part | Used |
| 4 | Precision knife | Cutting and cleanup | Important for corners and pad openings 30degree blade preferred | Hand tool | Used |
| 5 | 0.8mm drill bit | Drilling holes for component pins | Used to create precise holes for through-hole components | Drill bit | Used |
| 6 | Multimeter | Continuity testing | Used to confirm traces are isolated and connected correctly | Measurement tool | Used |
The fabrication workflow is organized around using the printed mold as the base PCB while the trace guide serves as a positioning and cutting jig.
The 3D prints should be cleaned so that there are no stringing or debris that could interfere with the copper tape application and adhesion. Imagine sticking protective film to your phone. :D
Check the fit of the mold and trace guide before proceeding.
Drill the necessary holes in the mold before applying the copper tape. Make sure to clean the 3D print again after the hole making especially the surface of the pads as they can be bumpy after drilling.
While making the holes after copper adhesion is an option, it is harder to drill on tape without damaging it.
Place copper tape on the mold part to cover the intended trace paths. You don't have to try to stick down everything at this point just enough for them to be positioned correctly.
Gently wipe down the copper tape with a little force around the traces to create a more secure adhesion and outline of the traces.
Use a lint-free cloth or just your sleeve to avoid leaving fingerprints on your beautiful copper.
Trim the outside edges of the copper tape to match the mold's outline, so that the mold will fit snugly with copper tape into the printed guide part
Gently tap the mold with a hammer or mallet to ensure the copper molds around the traces. You could use a needle or an awl or even a precision knife to trace around the traces for cut with the guide.
Take the mold out of the guide and inspect the traces for any gaps or misalignments.
This is a good time to use a hard flat surface to rub down the pads to ensure proper adhesion and poke around hard corners and edges to ensure all parts of the traces are properly adhered.
Use a precision knife to cut along the edges, following the outline of the traces carefully. Use your nailes or plastic objects to hold down the pad copper when cutting between pads.
DO NOT BE CAVALIER ABOUT THIS
Clean up and remove all of the unnecessary copper pieces and debris from the board.
If you are not confident about your skills, use a multimeter to check the connectivity of your traces.
Get a needle and poke the holes on the copper pads.
Reflection: The advantage of this approach is that the Trace guide can be reused for multiple iterations, and the mold part will be directly used as the PCB.
The outcome of this technique is a reusable method for creating PCB-like copper trace layouts without relying on a milling machine or chemical etching workflow. The printed mold acts as a physical cutting guide as well as a sturdy reliable PCB, and the tracing guide can be reused for multiple iterations which negates the need for repeated setup and alignment.
Reflection: I think this method can be beneficial for rapid prototyping and educational purposes to older students. Labs that may have trouble accessing traditional PCB fabrication machine, tools, and materials will benefit from this method also.
