Page 165 - Make Your Own PCBs with EAGLE from Schematic Designs to Finished Boards

Follow the Instructions

Each service will have a detailed set of instructions on how to use their service. Frankly, if they don’t
have this, then you probably should steer clear anyway. For example, we will look at the instructions
provided by IteadStudio’s Open PCB service. You can find the instructions for the company’s 5- by
5-cm basic green PCB service at http://imall.iteadstudio.com/open-pcb/pcb-
prototyping/im120418001.html.

In the section “Requirements on the Design and Gerber Files,” you will find instructions on the
dimensions of the board, which can be an unusual shape but must fit within the square specified. It
also tells you the Gerber files they require.

Most important, it also tells you the minimum line width and text height for silk screens of 6 and
32 mils, respectively. You would need pretty good eyesight to see text that small.
As for the copper, you will see that instructions specify a recommended width and separation of 8

mils. Because our thinnest tracks are 10 mils, we should be just fine.
It is also worth noting that if you want to make a tiny PCB, it may be a little irksome that because
your design is at the minimum board size, it may be tempting to do something called panelizing. This

involves putting multiple copies of the board design onto a single PCB design, with a row of very
close together holes separating the individual boards so that they can be separated by snapping them
off. This is usually not allowed, although if you simply mark a line to cut on the silk-screen layer, the
service will not object.
You also may be given the choice of different board thicknesses and finishes. Very small boards

2
can be thin: 1 mm typically would be fine for a board smaller than 50 mm . For bigger boards, 1.6
mm is a common thickness. There also may be options for being lead-free hot-air solder leveling
(HASL) and restriction of hazardous substances (RoHS). HASL will make the boards easier to solder

but is by no means essential. RoHS is a European Union directive intended to improve the
environmental impact of electronic manufacture. If you plan to sell your PCBs in Europe, you should
conform to this option.
Depending on the service, you will either need to upload the files, possibly enclosed in a zip file,
or separate and associate with an order number, which may require you to rename the files to include

your order code. Follow the instructions carefully.
The next step is that the files will undergo automated checks and will then be prepared for
fabrication. If you want to manufacture the boards yourself, at home, then photoetching is the way to

go.

Photoetching

Photoetching requires an ultraviolet (UV) light box, presensitized copper-clad board, developer, and
etchant. This is quite practical for single-sided boards but requires more care for double-sided
boards, where you need to align both sides accurately.

WARNING Photoetching uses noxious chemicals as well as ultraviolet light, which, while not

seeming bright, can do all sorts of damage to your eyes. Always observe the safety