How to etch a PCB at home: from a sketch or Gerber to a finished board
Most home-etched boards that fail, fail before the etchant: a print scaled by the printer, a mask printed the wrong way round, toner that never stuck, tracks too thin to survive. Here is the whole process, with the numbers that decide whether it works.
What you need
- Copper-clad board (FR4 or FR1), single or double sided, and fine steel wool.
- A laser printer (inkjet ink does not resist etchant) and glossy paper: magazine pages, photo paper for laser, or toner transfer paper.
- An iron or a laminator, isopropyl alcohol, acetone, and a permanent marker for touch-ups.
- Etchant: ferric chloride, or sodium persulfate, or hydrochloric acid with hydrogen peroxide.
- A plastic tray, gloves, eye protection, and a drill with 0.8 mm and 1.0 mm bits.
Step 1: get the artwork at 1:1
Artwork comes from one of three places: a design in KiCad or EasyEDA exported as Gerber, a picture of a logo or a circuit, or a sketch you drew. Whichever it is, the thing to get right is the size. A board 3% too big does not take its chips: a 14-pin DIP spans 15.24 mm between its outer pins, and 3% is half a millimetre, enough to miss the pads.
- From Gerber files: PCB etch mask, mirrored and at 1:1
- From a hand-drawn sketch: sketch to PCB
- From a phone photo or scan: photo to PCB
- From a logo or image: image to PCB
For a sketch, draw at 1:1 on plain white paper with a black marker at least 1 mm wide, mark the corners of the board, and measure the width before converting. A picture has no real size; you give it one.
Step 2: mirror the right layer
Toner transfer puts the print face down on the copper, so the print is reversed on the board. The top copper layer must therefore be printed mirrored. The bottom layer must not be: a Gerber already shows the bottom as seen from the top, which is mirrored compared with looking at the bottom, and the transfer reverses it back.
Step 3: print it so the toner is solid
- Print at 100%, "Actual size". Never "Fit to page". Measure the scale bar on the print before you go further.
- Put two or more copies on the sheet. Transfer paper and toner are cheap; a second attempt without reprinting saves the evening.
- Use the darkest setting with toner saving off. Grey toner is porous toner, and etchant gets through it.
- Glossy paper releases the toner; plain copy paper holds on to it.
- Handle the print by the edges. A fingerprint on the toner side stops it sticking.
Step 4: clean the copper
Scrub the board with fine steel wool until it is uniformly bright, then wipe with isopropyl alcohol and do not touch it again. Oxide and skin oil are the commonest reason toner lifts in patches.
Step 5: transfer
Lay the print toner side down, cover with a sheet of plain paper, and press with an iron on its hottest dry setting for 3 to 5 minutes with firm, even pressure, edges included. A laminator run 6 to 10 times is more even than an iron. The paper should turn evenly yellow. Too cool (under about 150 degrees C at the board) and the toner does not bond; tracks then come away with the paper.
Soak the board in warm water for 10 minutes and roll the paper off with a thumb, without scrubbing. Hold it to the light: every gap in a track is a break after etching. Fill gaps with a permanent marker.
Step 6: etch
| Etchant | Temperature | Time | Notes |
|---|---|---|---|
| Ferric chloride | 35 to 45 C | 10 to 20 min | Cheap, forgiving, stains everything brown. Opaque, so lift the board to check. |
| Sodium persulfate | 45 to 55 C | 15 to 30 min | Clear, so you can watch the copper go. Needs the heat. |
| HCl + hydrogen peroxide | Room temperature | 2 to 5 min | Fast and clean, but corrosive fumes: outdoors, with care. |
Rock the tray or bubble air through it: fresh etchant at the copper speeds the job and keeps it even. Check every few minutes and stop as soon as the bare areas are clear. Every extra minute undercuts the edges of the tracks, and a 0.3 mm track can lose half its width.
Step 7: clean up, drill and protect
Remove the toner with acetone. Drill at the centring dots (0.8 mm for most component leads, 1.0 mm for pin headers and larger leads) with the board on scrap wood. Tin the copper with a soldering iron or a tinning solution, or spray it with solder-through lacquer, so it does not oxidise before you solder.
- Neutralise used ferric chloride with washing soda or take it to a hazardous waste site. Never pour copper solutions down the drain.
- Store etchant in a plastic bottle with a vented cap, labelled, away from metal.
Design rules for boards you etch yourself
| Feature | Toner transfer | Photoresist | Board house |
|---|---|---|---|
| Track width | 0.4 mm or more | 0.25 mm | 0.15 mm (6 mil) or less |
| Gap between copper | 0.4 mm | 0.25 mm | 0.15 mm |
| Pad for a through-hole lead | 2.0 mm | 1.8 mm | 1.6 mm |
| Text height on copper | 2.5 mm | 1.5 mm | 1.0 mm |
The image to PCB pages measure the narrowest line in your artwork and say which of these it passes.
When to stop etching and order instead
Home etching wins for a single-sided board this week. Once you need two sides with plated holes, fine-pitch surface-mount chips, or more than a couple of copies, a board house is cheaper than your time: the same Gerbers this guide prints from are what they make the board from. Check them first in the Gerber viewer.