Multi-layer PCB tutorial

[garvind25]

Hi,

I wanted to know if there are any KiCAD tutorial for making 4 /6 layer PCBs (for v 4/ 5.1). If so, where can I get it pls.

Thanks,
Arvind Gupta

[BobZ]

I hate to see your request go completely unanswered. I infer from the lack of response that nobody has thought of such a tutorial. However I am also thinking that I can begin listing some “rules of thumb” (let’s say rules which are applicable in 90% of cases) to get you on the right track.

What I say below is not particular to KiCad but apply to pcb layout in general.

1. A common beginner mistake is to underappreciate the importance of proper pcb layout. One DC/DC converter design of mine was laid out by a pcb designer without engineering input. There were no netlist errors; yet the result was 0.0% functional. I could not get the slightest burp of operation out of this board.

2. The first thing to understand in layout is to identify what is critical. That is a huge topic which is too big for me to cover here, but in many cases the IC datasheets will offer a lot of helpful information. Bypass capacitors should be located as close as possible to the power supply pins. Tracks connected to amplifier inputs should be short, with resistors and capacitors located close to the input pins. There is much more…

3. As I infer in (2) above, component placement is the first thing to get right after understanding what is critical.

4. If there are 1000 possible pcb layouts for a schematic design then maybe 50 of them will be good.

5. In a 4 layer design, the outer two (of the three total) dielectric layers will generally be thinner such as 0.2 mm. With this scheme I would normally recommend using the second (of four) copper layers to be a ground plane. With most of the circuitry on the top layer, that will provide optimal self shielding (minimal stray inductance and inductive coupling) which (at least in my power oriented experience) addresses the biggest problem with a poor layout. Other circuit connections can be connected on the bottom, and the third layer can be used for power and other cross-board interconnects.

6. In a six layer design I would normally use layers 2 and 5 as ground planes, and (like the 4 layer design) put most of the local connections on the top and bottom layers. Then you have two internal layers for power and/or cross-board interconnects.