Printed circuit board
From HvWiki
A printed circuit board consists of copper sheets laminated onto a non-conductive substrate where the copper is etched away in areas to form conductive paths for power and signals.
Maximum current
| Maximum current through 35 µ foil on a PCB at a given overtemperature | ||||||
| Width | 10°C | 20°C | 30°C | 60°C | 75°C | 100°C |
|---|---|---|---|---|---|---|
| 0.5 mm | 1.3 A | 2 A | 2.3 A | 3 A | 3.5 A | 4 A |
| 1 mm | 2 A | 2.8 A | 3.1 A | 4 A | 5 A | 6 A |
| 1.5 mm | 2.6 A | 3.7 A | 4.4 A | 6 A | 7 A | 8 A |
| 2 mm | 3.2 A | 5 A | 6 A | 8 A | 9 A | 10 A |
| 4 mm | 5.5 A | 8 A | 10 A | 11 A | 15 A | 16.5 A |
| 6 mm | 8 A | 11 A | 13 A | 18 A | 21 A | 23 A |
| 8 mm | 9.5 A | 13 A | 16 A | 22 A | 24 A | 26 A |
| 10 mm | 11 A | 16 A | 20 A | 27 A | 29 A | 33 A |
Minimum distance between tracks (DC)
- 50 V = 0.3 mm
- 150 V = 0.6 mm
- 300 V = 1.2 mm
- 500 V = 1.8 mm
High voltage construction techniques
One doesn't absolutely *need* a PCB. It's just a convenient way of organizing electric parts and the connections between them. Alternatives include
- proto-board -- a generic PCB that can be used for any circuit
- "rat's nest" -- just solder the components directly to each other
- solderless breadboard
- "dead bug" ...
- wire-wrapping
- gold-dot above copper plane
- ...
The traces ("printed wires") that carry a lot of current need to be wide.
The traces that carry high voltage should be well-seperated from other traces.
Some PCBs are "single layer". Others are "two layer" (copper on both the "top" and "bottom" sides). Others have 2 or more "internal layers". The more layers you have, the more difficult/expensive it is to line them all up correctly and bond them to each other (mechanically and electrically).
There are various ways of making PCBs yourself:
- Homemade PCB
- Easy Printed Circuit Board Fabrication Using Laser Printer Toner Transfer, by Thomas P. Gootee
There are dozens of places that, once you have a PCB layout, will fab it and ship the empty board back to you for around $40 each for single boards, $5 each for a dozen or so identical boards (for "postcard-sized boards". Larger boards are, of course, more expensive). List of PCB fabs.
