Stelios's Place

PCB Manufacturing at home

   I always wanted to be able to make my own PCB boards at home. That way, I could easily move from breadboarding a design to actual PCB making pretty fast (~1 hour total time). I have been using perf-boards but I never actually liked the results. They don't quite look professional, do they?

   I tried several applications to help me design the PCB circuit. I finally ended up using the 'free' ExpressPCB software for both my schematics and PCB drawings. I felt this software it's simple enough to get started and also it mostly stays out of your way letting you do your things. It lacks features such as auto-router but I enjoy routing tracks by hand. At least now and at least for simple boards. I can also run this software under Linux using the Wine application, which it's pretty good!

   You can have your board manufactured by the ExpressPCB company or you can do it your way. I preferred to do it my way. If you choose this path, you will need to tweak a few things in the software to help you print and etch better pcb boards. Here are some notes after playing around and making a few test boards:

   You will need to change the width if the traces and make them thicker. This way, while you exposing your pcb or etching it you will avoid problems with missing or discontinued tracks. Also, your pads or holes for your through-hole components should be a bit thicker. You will have more copper around the hole to solder your component when you're done drilling the board.

I use the following numbers:

• Trace size: 20mil
  
• Clearance around traces: 25mil

I have also created my custom pads, with the following sizes:

• 70mil round pad with 25mil hole
• 70mil square pad with 25mil hole

I have also created my custom components using this values, especially the pad sizes for the DIP footprints. You can get them here.

   I started using fill planes in the design. They do make etching process faster. After I have finished laying out the tracks I fill the bottom layer with copper. You will get a warning when altering the 'clearance around traces value'. My board came out pretty OK after I have changed the number and the thermal pad was nicely attached to the filled plane.

   As a last tip, I mostly do single sided PCB boards using jumper wires if I have to. Since I'm not using SMT components, I use the bottom part of the board for the copper tracks. Using the software, I draw the tracks on the bottom copper layer so I can print without the need to mirror the image or anything else. I'm not using a 'Print to PDF' step before printing on the slide. I print directly to the slide using the 'best quality' settings on the printer.

Comments and suggestions are welcomed.



~steliosm