This is an old revision of the document!
Table of Contents
Objectives
To design a machine, method, or process to generate one-off printed circuit boards with the following conditions:
- Time from finished PCB layout to physical board must be less than 3 hours excluding setup.
- Traces for TSSOP packages must be possible (0.19-0.3mm traces, 0.65mm pitch).
- Two layers must be supported and properly aligned with minimal frustration.
- Board quality must be consistent and dependable.
- Minimal tool changes or chemicals.
Methods
Traditional
Toner Transfer
Works. Not well.
The traces are laser-printed in reverse onto some sort of glossy paper (e.g. magazine or photo paper), then transferred to a copper-clad board using a hot clothing iron or t-shirt press. The traces transfer to the board and act as an etch-resist.
Issues:
- A dedicated clothing iron is required
- Inconsistent transfer (i.e. gaps in solid areas)
- Multiple layers are difficult to align
UV Exposure
Works. Not well.
The traces are laser-printed onto clear acetate, then overlayed on a copper-clad board and exposed evenly to UV light. The board is then washed in developer solution that either washes away the exposed portions of UV-sensitive chemical, or wash away then unexposed portion, depending on chemical process used. The traces that remain on the board act as an etch-resist.
Issues:
- UV chemicals are required to coat the board OR
- Presensitized boards must be used, which are:
- More expensive
- Inconsistent from different manufacturers both in exposure time and development time
- Require handling in a darkroom
- Require rushing the process so as not to allow ambient light to ruin process.
Laser Cutter
Spray Paint
Has potential.
Sharpie
Has potential.
Sugar
Doesn't work. Air assist. Inconsistent.
Toner
Doesn't work. Bad idea. Not dumb enough to try this.
Issues:
- See above for air assist issues.
- Nigh-impossible to work with cleanly.
- Biohazard.
Acrylic Trench
Works poorly. Large traces. High trace resistance. No soldering.
Printers
Inkjet
Works. Not well.
- Pigment/dye
- Running/blurry edges
- Alignment
Laser
Works. Not well.
- Inconsistent fill
- Alignment
Wax Inkjet
Jeff Gough had some success with this.
Dye-Sublimation
Has potential.
Thermal Transfer
Has potential. Similar to dye-sub.
Thermal Wax Transfer
Has potential. Similar to dye-sub.
Wax Printer
Xerox Phaser wax printer. Has potential. Expensive. Huge.
Mechanical
CNC Milling
Works. Not well.
Vinyl Plotter
Works. Not well.
Electrical Discharge Machining
Has potential. Difficult for precision. Expensive. Terrifying.
Electro-Chemical Machining
Doesn't work.