PCB etching instructions

Making PCBs @ LHS

Here's the overall process

<graphviz border='frame' format='png' >

digraph rfboard{
  rankdir=TD;
  size="14,9!";

  cleaning [label="Copper board cleaning",shape=box,style=dashed];
  photoresist [label="Photo resist coat",shape=box,style=dashed];
  resist_cure [label="Photo resist curing",shape=box,style=dashed];

  breadboard [label="Breadboard",shape=box];
  board_layout [label="Board schematic",shape=box];
  uv_exposure [label="UV exposure",shape=box];   
  develop [label="Develop (Tank A)",shape=box];
  etch [label="Etch (Tank B)",shape=box];
  strip [label="Stripper (Tank C)",shape=box];
  drill [label="Drill",shape=box];
  solder [label="Assemble and solder",shape=box];

  breadboard-> board_layout [label="Fritzing"];
  board_layout-> uv_exposure;
  cleaning->photoresist;
  resist_cure -> uv_exposure;
  photoresist->resist_cure;
  uv_exposure->develop;
  develop->etch [label="Spray wash"];
  etch->strip [label="Spray wash"];
  strip->drill [label="Spray wash, dry"];
  drill->solder;

} </graphviz>

Note : see Pcb for other references

Board Schematic

Plain paper works surprisingly well! The printers at the space do a good job.

If you use eagle, you can use the print option (as opposed to exporting an image). Print on normal paper first and check dimensions on some components.

Some people get better (resolution mostly) results with acetate, but this needs to be special laserable acetate. Do not use normal transparency! Melting a sheet onto a fuser is expensive!

UV Exposure

W

Make sure your print is the right way round so that your board isn't back to front when it's etched!

5 minutes with acetate and something like 15 with paper. The uv board should look green with faint lighter green traces where your traces are.

PCB etching: Developer

Put the board in the developer (tank A), at the moment the heater for the developer is broken { note: is this still true ? } so it takes longer than the 30 seconds. What you need to look for is all the copper is exposed when you check it. Only the tracks should be coloured (green with the uv exposure board).

Note : the developer in tank A is from Mega Electronics, also sold through Rapid. It works well with photo pcb material from the same source. It does NOT work with Maplin photo material !

Etch

follow instructions on the notice, but the board is done when all the exposed copper is removed. The balance is removing too much copper and getting breaks in traces vs not enough and some small closely laid traces may have bridges.

Stripper

use the stripper for the specified time then scrub the black off and you should have nice copper traces! Use a multimeter to check for bridges.

See also

Project:DIY_PCB_Making

Project:PCB_Making