Q. Which way should I run my tracks on a double-sided board?

A. Usually tracks on the solder-side are run horizontally, and vertically on the component side.

Q. What drill sizes should I use?

A. Usually only a couple of drill sizes are needed. Try to limit the number of drills you use to eight, this avoids extra hassles for the PCB production line people.

Q. How do I get footprints for resistors, capacitors and diodes?

A. In schematic, double click on the component so that you are editing its attributes. Here you can change its designator (e.g. R4), part type (e.g. 100k) and footprint (e.g. axial0.4). These attributes are exported along with the net list, so that PCB knows what footprints to use, and what labels to attach to them.
The footprints you will commonly need are

• 0.25W resistors axial0.4 (Axial explains the way the leads leave the body of the component)
• small signal or 1A diodes diode0.4 (The 0.4 is 0.4", the spacing of the holes)
• capacitors rad0.1 or rad0.2 (Rad stands for radial - the way the leads exit the body - radically)
• electros rb.2/4 (Radial Bipolar, 0.2" lead spacing, 0.4" case diameter)
• ICs dip8, dip14

All the most common footprints are in a library called advpcb.lib. You can add this to the list of searched libraries by using add/remove libraries command.
If you don't import a net list, you can still place footprints of your choosing by simply placing a part. You choose a footprint from the library.

Q. What do you mean by this: Minimum via size 40 thou outer, 25 thou inner?

A. A via is a plated through hole (PTH), placed on the PCB purely to connect two tracks on different layers. For you, this is the top and bottom layers, component side and solders side. Since there is no component leg going through the hole, just the copper plating, we could make the hole any size we wanted. But we keep it above a minimum hole size, so that the drill isn't too tiny, fragile, expensive etc. It also allows them to drill a stack of PCBs at once (say up to about 5 deep). For BEC, this is 25 thou (0.6mm). Then you need a certain thickness of copper pad around the hole, to ensure they can cope with a small misalignment, amongst other things. The ring doesn't have to be big, since we aren't soldering to it. The 40 thou (1mm) is the diameter of the via "pad". This only allows 8 thou (0.2mm) of copper ring, which is pushing the 10/10 rules a bit, when you look at it. I'd be working with 45thou dia, with a 25 thou hole. If you are doing a single sided layout, then you don't even need to know what a via is.

 

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