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DIY Printed Circuit Boards

A search around the web will dig up plenty of how-to articles for this; but I've learned a couple extra tricks so I'll add my version to the mix.

Many ham operators like to create there own electronics; everything from simple little devices to full HF radio sets. Of course, for very basic circuits, there are options such as perfboard, wire wrap, and the like. None of those gives the polished finished product, and flexibility of design that a custom circuit board does.

PCB Boards

In keeping with this site's focus on beginning hams, I'll start out with what a circuit board is made up of. I will assume if you are reading this article, you have at least looked at commercial circuit board. Probably, you noticed all the little parts soldered to it, but didn't pay much attention to the board itself. Really, that's kind of backwards though - those components are mostly all pretty standard stuff; the real 'personality' of the board, the essence of what it does for us, and the intellect of design is found in all the interconnections on the board itself. That is the part we'll be talking about here - the board itself.

When a circuit board(called PCB for printed circuit board) is first made, it is a thin, solid layer of copper on one or both sides of a sheet of some non-conductive material - no holes, no lines, just a blank canvas. What's required to turn it into the newest gem of electronics is to remove some specific parts of that copper to create individual wires (called traces). That's what this article is about; how to accurately remove the copper from the board in just the right pattern to create the traces we want.

Resist

To do so, we apply something called resist to the copper where ever we want the copper to remain(ie. draw our circuit with it). There are several kinds of resist, depending on what process we choose, but any resist needs to have two basic qualities: It must protect the copper from the removal process, and there needs to be a way to get in on the copper in the correct place. The first part is relatively easy, in plain english it is anything that can stop metal from corroding like paint or grease. The second property depends on the process being used. The one I'll describe here ultimately uses static electricity inside of a laser printer to create the desired pattern. Other common methods include hand drawing the resist with a special pen and photosensitive coatings with transparencies.

Board Design

To get started, you must of course have a circuit board design. This is the actual traces that will be on the board; not the schematic diagram. While you might think initially that they can be one and the same; that's not the case except for the most basic of designs. In a schematic, there is no issue with wires crossing, components sizes, component physical location, component interactions, etc. On a circuit board, that's a different story. Many components have specific locations and two traces crossing each other would have to be formed from different layers of copper.

In other words, schematics are drawn with the goal of being understandable; board layouts are drawn with the goal of being functional. Heat producing parts have to be placed to allow heatsinks and/or fans, RF components must be inside shields, controls must be on the control panel, etc. In addition to those placement considerations, we will also want to minimize traces crossing each other - which requires either a jumper wire(messy) or additional copper layers(costly).

If you have found a pre-designed project you wish to build, its likely that the author has a pre-drawn board layout for you to use. If you are scratch building, you'll have to create your own. My professional background is in graphic design, so I'm comfortable creating such designs in generic graphics software. Many purpose-designed board layout software packages will make a valiant attempt at creating it for you from the schematic. My only recommendation for this is to explore the options, and use what works for you.

So, enough introduction already! The next section will get into the action.