0
\$\begingroup\$

I'm trying to create my first PCB after having too many problems wire-soldering every single wire.

I learnt KiCAD yesterday and so far it seems like a very good application.

For creating the scheme, it was relatively easy, and I think it looks quite neat (but if you have improvements, let me know). Note: I haven't checked all resistor values yet, for me most important was to learn how to make a PCB.

enter image description here

It is a MIDI In/Thru/Out PCB.

However, when I route it (manually), it's getting quite messy.

I want to use two layers to reduce cost (it's a hobby project).

Some questions:

  1. There are quite some complicated routings, however, when I rotate or move symbols (components), I have to restart routing those again, which is quite time consuming. So the best is probably to place/rotate the symbols as good as possible before starting to route the wires, however, it's hard to see beforehand what wires will cause problems (especially when using references in the circuit above). Is there some guideline how to tackle this problem?

  2. Should I start wiring the short/simple wires first, or should I start with the difficult ones (one hoping the difficult ones will not make even the simple routings to be harder)?

  3. According to the KiCAD manual it is a good practice to use one layer for GND, however, I use some vias. What I now did is to use the via and continue via the GND plane. Or is it best to make the via's via the GND plane as short as possible and use another via to return to the main layer as soon as possible (thus using two via's, one to go to the GND plane and one to return from it) ?

  4. Or should I - since I only have two layers - forget about a GND plane, and try to find a better way to divide the routings over the layers? (e.g. GND + VCC via one lane, signals via the other, or signals + GND via one layer and VCC via the other?

(note: I also see now there is some unfinished line, but I will ask how to find those in the KiCAD forum). The above questions seem very generic.

Sorry for these - for you - probably basic questions, for me it's my first 'real' PCB.

enter image description here

\$\endgroup\$
  • 1
    \$\begingroup\$ Autorouter FTW!!! not ... I'd strongly recommend you route the traces manually, and use sensible sizes for them & the vias. \$\endgroup\$ – brhans Jun 14 '19 at 23:25
  • 1
    \$\begingroup\$ Also, it looks like rotating some items will help routing, and more use of the second layer. These types of issues become easier to spot after routing a few boards manually. \$\endgroup\$ – Tyler Jun 15 '19 at 0:02
2
\$\begingroup\$

I see a couple of serious problems here.

  • The footprints you're using for diodes and resistors don't look right, unless you plan on mounting all of these components vertically. (And even that might be a tight fit.) Use horizontal footprints for these parts.

  • The footprints you're using for connectors look like large terminal blocks, designed for high current devices. Check the size on these, and consider using a smaller 0.1" spaced connector, especially for logic-level connections (like MIDI).

  • A lot of nets are routed long distances around pins or other nets rather than using vias, and I see at least one disconnected net under U1. Once you've changed the footprints for your diodes and resistors, move some parts around and try to clean things up a bit.

| improve this answer | |
\$\endgroup\$
  • \$\begingroup\$ Thank you very much for your answer. Actually, I deliberately use vertical footprint to save space (I want to put the PCB in about 48mm x 96 mm (appr), so I can double the PCB and cut it in two, and putting it in low cost enclosures (of around 100 mm). I indeed use 5.04mm terminal blocks, I have quite a lot of them and couldn't find (cheap) 2.54mm terminal blocks. Although I might consider pin headers and solder wires directly to them. I will use more vias. \$\endgroup\$ – Michel Keijzers Jun 15 '19 at 0:15
  • \$\begingroup\$ And you are right about some unconnected wire, it is actually a leftover from autorouting, and I found a way to get rid of them without checking the PCB manually (I'm a beginner in KiCAD, learnt it today). \$\endgroup\$ – Michel Keijzers Jun 15 '19 at 0:15
  • 2
    \$\begingroup\$ You aren't anywhere near needing the space savings from vertical TH parts. There's tons of room available on that board -- you should have no trouble using horizontal footprints. \$\endgroup\$ – duskwuff -inactive- Jun 15 '19 at 0:18
  • 1
    \$\begingroup\$ I think you have the wrong footprint for the ferrite beads too, the one you have that looks like a spool inductor with radial leads. \$\endgroup\$ – Jasen Jun 15 '19 at 0:24
  • 1
    \$\begingroup\$ j2,j3,j4 should be replaced with either through-hole DIN sockets or something smaller for signal wire termination. place the capacitors closer to the ICs and use shorter traces to connect them. \$\endgroup\$ – Jasen Jun 15 '19 at 0:30

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.