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Besides the obviously poor choice of a breadboard for a product, what benefits are there to a PCB over things like protoboard with wires soldered? Is it just the size and amount of "wiring" that's already done on a PCB, or is there a benefit to the thin conductive lines on a PCB?

To clarify, sorry if I was vague, this is primarily a technical question about the electrical properties of circuits on a PCB compared to other methods but I'd be pleased to read about other criteria that differentiate the PCB from other circuit implementations.

In short, why should I go to the trouble of making a PCB?

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    \$\begingroup\$ Are you talking about products? or prototypes? General electrical characteristics, or (more broadly) production reasons? Can you clarify? \$\endgroup\$ – Andrew Spott Sep 12 '16 at 22:04
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    \$\begingroup\$ Even for a prototype, ease of assembly and avoidance (or at least reduction) of mistakes are big advantages. \$\endgroup\$ – Brian Drummond Sep 12 '16 at 22:11
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    \$\begingroup\$ A ground plane or interleaved tracks lowers the transmission line impedance to reduce ringing of fast edges with long tracks. It also looks better and allows SMD parts. \$\endgroup\$ – Sunnyskyguy EE75 Sep 12 '16 at 22:13
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Electrically, there's not a huge difference in many common scenarios. If you're working with pure DC, relatively low current levels, fairly low voltages, etc., then you can get by fine with protoboard and soldered wire, etc. The biggest disadvantage there is that it's potentially more work to build your board (assuming you have the PCB's fabbed by a fab and aren't etching your own or whatever), and it's almost certainly harder to get a reproducible build that behaves the same way.

Altogether, the protoboard and wire approach doesn't scale as well. If you're building some one-off thing for yourself or just building a prototype, it might not matter. But if you're building something that you want tens or hundreds (or more) of, you will want to use a PCB.

The other case where a PCB is clearly better is when you're working with higher frequencies, especially up in the RF range, where you start having to worry about crosstalk / inductive coupling, noise, etc., and minute changes in impedance and capacitance become critical factors. In those cases, it's probably easier to build a PCB that takes those things into account.

Another "non electrical" factor is that a lot of newer components aren't available in old fashioned through-hole DIP packages. If you want to use the latest IC's you may almost be forced to use a PCB, or at least to use a small shim / PCB "adapter" that the SMT component solders to, that lets you treat it as through-hole.

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PCBs typically have lower parasitic inductance and capacitance than a breadboard.

Impedance can be controlled for high frequency signals. Circuit density can usually be higher.

In circuit and functional testing is easier. Manufacturing is WAY easier.

Conducted and radiated EMI will be less for a properly laid out board.

Reliability of a PCB should be better, especially if there's shock and/or vibration.

There are other benefits that I'm not thinking of at the moment, but I'm sure others will jump in.

Of course it's possible to make a complete mess of a PCB with poor layout and manufacturability. PCB layout is a skill that requires a lot of experience for all but the simplest least critical circuits.

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    \$\begingroup\$ And the final product will be closer in build to the prototype and more likely to work. \$\endgroup\$ – KalleMP Sep 12 '16 at 22:15
  • \$\begingroup\$ Me: Googles "parasitic inductance". #blush \$\endgroup\$ – Bernhard Hofmann Sep 12 '16 at 22:23
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    \$\begingroup\$ @BernhardHofmann It's just jargon for extra capacitance you probably don't want. \$\endgroup\$ – 0xDBFB7 Sep 12 '16 at 22:40
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Protoboards with wires take a much longer time to assemble than PCBs. They also lend to assembly mistakes that take time to debug. They get real nasty for anything above modest complexity.

There was a time when wire wrapping was the preferred method for complex prototypes, as PCBs were expensive and slow. Now I wouldn't dream of wire wrapping.

Cap all this, and all other answers, with the fact that many ICs are only available in SMD packages, and the fact that PCBS are now dirt cheap and fairly fast. When soldered using a tiny smidgen of attention, they come out error free. Clear winner.

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    \$\begingroup\$ A lot of younger engineers have never heard of wire-wrapping. Remember troubleshooting an incorrect wrap? Having to unwrap and re-wrap several layers of wire to get to the bad one? I don't miss that at all, LOL. \$\endgroup\$ – John D Sep 13 '16 at 4:35
  • \$\begingroup\$ Wire wrapping is a still a great technique for linking together evaluation boards. \$\endgroup\$ – Chris Stratton Sep 13 '16 at 4:48
  • \$\begingroup\$ I never even knew there was this wire wrapping method. Just read about it, thank you for educating me. Any day I know more than yesterday is a good day. And it's only 06:20! \$\endgroup\$ – Bernhard Hofmann Sep 13 '16 at 5:20

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