PCB Design for Noobs

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PCB Design for Noobs

Post by Repeater » Thu Dec 22, 2011 11:42 am

I have an original circuit that I've been soldering up on perfboard with a ton of jumper wires and am getting sick of it taking all day to build 'em. I'd like to transfer the schematic over to a pcb so that I can build them faster and have more standardized production procedures.

I will be using this for commercial devices eventually and I don't want to violate any software license agreements...

A few questions:

Are there any good books or websites that have general guidelines for pcb design?

Is there any software (perhaps free?) that can transfer a schematic directly to a pcb design that only requires a few tweaks to get right?

Has anyone done college coursework or taken other classes in pcb design and would they recommend that route?

What stupid mistakes do people tend to make when they're starting?

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Post by bazrush » Thu Dec 22, 2011 8:03 pm

I'm at about the same stage as you right now. I've got an awful lot of stuff hung together with sticky tape and solder.

Try designspark.com for a free PCB design program, or there are cheap and free versions of Eagle CAD I found today. Looks like a bit of a learning curve on both of them though!

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Re: PCB Design for Noobs

Post by andrewF » Thu Dec 22, 2011 8:22 pm

Repeater wrote:
1.Are there any good books or websites that have general guidelines for pcb design?

2.Is there any software (perhaps free?) that can transfer a schematic directly to a pcb design that only requires a few tweaks to get right?

3.Has anyone done college coursework or taken other classes in pcb design and would they recommend that route?

4.What stupid mistakes do people tend to make when they're starting?
1. Yes a lot, have a google to find one that suits you. Also most programs have active Yahoo groups where you can get info - especially ExpressPCB, protel and Eagle. Designspark have their own forum linked from their homepage.

2.There is no software autorouter I would completely trust, the amount of time you spend setting it up and fixing the fuckups is about the same as the time you would spend designing the layout yourself

3. i have done courses at tech & uni, they do not really teach you anything about layout that you cannot work out yourself from following some tutorials online and experimenting

4. tracks too thin, components too crowded together (i still do this :oops: )

DesignSpark may have be a bit harder to learn but it seems a good choice, plus it generates gerber files which means you can choose your manufacturer rather than being locked into whoever made the program. i have used ExpressPCB for the past few years and PCBs made at Futurlec, it is easy and not bad pricewise. These days there are some really cheap options available for PCB manufacturing but require gerber files, so I am switching over to DesignSpark

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Post by paults » Fri Dec 23, 2011 12:03 am

http://www.lis.inpg.fr/realise_au_lis/kicad/

Free, outputs Gerbers, has all you need. Multi-platform and not to horrible to learn and use.

Paul's Everything you need to know about PCBs
==============================

1) use 12mil lines and 12mil spacing for signals.
2) use 25mil lines for power as a minimum. 50mil is best
3) for standard parts like caps, resistors and ICs use 60mil pads with 40mil holes
4) for the vias (to transfer the trace from 1 side to the other) use 40mil pads with 18mil holes
5) for resistors and axial ceramic caps use 400mil pad-to-pad spacing
6) for radial/film caps use 200mil pad-to-pad spacing

1mil = 0.001inch so 60mil = 0.060in

Note: when I say pad-to-pad it's really "hole-to-hole" but I'm using standard nomenclature. You want the resistor leads bent on 400mil spacings and 95% of caps used for filters are 5mm = 200mil spacing.

This will cover most of what you need.

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Re: PCB Design for Noobs

Post by Joe. » Fri Dec 23, 2011 1:28 am

andrewF wrote:i have done courses at tech & uni, they do not really teach you anything about layout that you cannot work out yourself from following some tutorials online and experimenting
We actually had to work through the online tutorials at the beginning of our course :sadbanana:
I really only started to learn once I started doing projects and started making mistakes; it was solutions & tips from experienced people that really helped out.
If I was you I'd start looking around at PCB Software forums, what are active, and which look friendly.

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Post by Tombola » Fri Dec 23, 2011 2:13 am

Such a great thread - amazing to have paults teaching PCB lore...

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Post by Repeater » Fri Dec 23, 2011 2:41 am

Y'all are the best. As a person who is into this stuff, but not formally trained, I really appreciate the advice. Keep it coming. I'm hoping to make some headway this summer once my schedule frees up. If only apprenticeships were still in the vogue...

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Post by andrewF » Fri Dec 23, 2011 3:10 am

paults wrote:
1) use 12mil lines and 12mil spacing for signals.
Is there any advantage to using thicker lines for signals? I tend to make them 20-25 mil if there is space, 15 if there isn't.
cheers

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Post by Jarno » Fri Dec 23, 2011 3:25 am

Since I'm using toner-transfer myself, I usually go for widely spaced thick tracks (50mil or so), since these are more reliably put on the copper clad, furthermore peroxide and muriatic is a pretty violent process, so extra width of the tracks protects against faults due to under etching.

But purely from a signal standpoint, don't think there's much to be gained, colleague of mine had a board for a 25Gig link, and it used pretty thin tracks for the differential pairs.

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Post by Electronic Battle » Fri Dec 23, 2011 7:20 am

As far as software is concerned:

http://www.designspark.com/

which gives you free schematic capture, an interface to LTSpice so you can model your circuits from the captured schematic - no need to enter it twice - and a PCB output which generates Gerbers and NC drill files.

As far as getting boards made, ITeadstudio is unbeatable: 10 double-sided silk-screened and solder-masked PCBs for approx. £25 including P&P to England.

http://iteadstudio.com/store/index.php?cPath=19_20

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Post by bazrush » Fri Dec 23, 2011 9:31 am

Is that ridiculously cheap!!? It seems about a tenth of the prices of the places I was just looking at! Wow ...

What's the lead time once you've submitted an order?

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Post by Electronic Battle » Fri Dec 23, 2011 9:41 am

The two sets of boards I have had from them took about ten days in total from receipt of order to the product landing on my doormat. The quality is excellent, by the way.

They're the only people I shall use from now on.

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Post by kjackman » Fri Dec 23, 2011 10:11 am

Has anyone here done synth PCB layout with SMT parts?

Package sizes are getting incredibly small, pretty much microscopic. Size 01005 resistors look like grains of sand! No idea how they pick and place grains of sand...

Anyway, it made me wonder just how small we could make some of the DIY synth designs, using the smallest package sizes, cramming the parts on both sides of the board, and using as many PCB layers as it would take. Obviously not for putting together by hand in the basement lab!

But how small and close together can those PCB traces get without causing problems? Curtis CEM chips put whole VCAs, filters, and envelope generators on a chip, which is much smaller than an SMD PCB, right?

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Post by bazrush » Fri Dec 23, 2011 10:14 am

Just use one of these no?

I'm saving up.


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Post by EATyourGUITAR » Fri Dec 23, 2011 11:20 am

bazrush wrote:Just use one of these no?

I'm saving up.

[video][/video]
it pounded that PCB so fast I think it smoked a cigarette after :hihi:

also, @ OP this other thread is about 9 days old. should be on the first or second page now.

viewtopic.php?t=48458

but to answer your unique question of how do we fuck them up. there are a lot of ways. things not being connected that should be. things connected that should not be. traces too thin. edges too sharp (only applies to DIY etching). pads not big enough. pads too close together. parts too close together. through hole not big enough for rectifier diodes that have huge leads. not putting mounting holes in the layout. ic pins come in two or three sizes. depends on if you are using sockets and if they have machined pins. on some designs like high gain amps or anything in the Mhz range, or ultra low power consumption digital electronics, you need to design your pcb to minimize EMI, RFI and any other kind of noise. if you operate digital electronics at lower clock speeds and 5v you have a lot less to worry about. the hardest part is seeing the whole project in 3d and designing PCB's with all your pots, jacks, switches, LED's on board. this is done to save time, space, and money. the PCB mounts itself to the panel through your pots or jacks. in that situation you don't need 4 mounting holes for standoffs in the corners of your PCB but it is also the most difficult to design.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

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Post by corex » Fri Dec 23, 2011 12:48 pm

DesignSpark is free? What's the "activation" bit for?

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Post by Electronic Battle » Fri Dec 23, 2011 1:46 pm

corex wrote:DesignSpark is free?
Yes, it certainly is.
corex wrote:What's the "activation" bit for?
As far as I can remember, it's just a way of getting your email address so as to tell you about upgrades. I registered a couple of years ago so I can hardly remember. It's not intrusive though.

Designspark is the best of the bunch as far as I am concerned. I've tried something in the region of seven other free packages and whilst they're all pretty good, Designspark is the one that I found easiest to get to grips with. There's a lot of footprints, the 3D part is fun and the Gerber export is painless. Now that you can interface it with several spice packages (LTSpice being my preferred one, also free of charge by the way), I think it is something which sets it apart form the competition. Although I expect they'll do something similar soon if they haven't already.

It all boils down to being a case that nobody needs to suffer breadboard/veroboard stuff anymore. You can draw circuit, probably model it if necessary, generate a PCB and get it made in qty of 10 for less than single board prices in UK/US/EU.
Last edited by Electronic Battle on Fri Dec 23, 2011 1:59 pm, edited 1 time in total.

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Post by frijitz » Fri Dec 23, 2011 1:57 pm

i've had good luck with the freepcb.com program.

:grin:

Ian

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Post by ultrashock » Fri Dec 23, 2011 4:25 pm

I solder 0603/sot363/tsop14-16 at home with hot air - no problems at all especially when you are well prepared:
- have some magnifying lens or special glasses, thin tweezers;
- a bit practice and do not afraid smd :)
- manufactured pcb - in that case details very easy and quickly stay at their places under heating of soldering paste under surface tension force.
- all sm-details are laid out in small boxes out of reels. That's very important since it takes a lot of time in total further to get every detail from reel. I recommend that special boxes for everyday pills for patients with sclerosis or amnesia:
Image

Some of my friends solder 0402 with thin soldering iron - they don't like hot air since it blows away their details :)
0402 are good since their grid is just like the width between pins in ordinary soic - one can make really short feedback loops at opamps when working in hi-freqs.
Diptrace is good since has built in 3d-preview of your PCB.
Eagle is wide-spread and has huge library and wide community support (forums, edu. video etc). Both are free for non-commercial use with restriction to 2 layers which is pretty enough for modular stuff

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Post by emdot_ambient » Fri Dec 23, 2011 7:22 pm

Great thread...just starting to do this, too. Though my first projects will be very simple, like a "chicklet" PCB for use with these push/pull DPDT pots:

http://www.smallbearelec.com/Detail.bok?no=619

They're supposed to be PCB mounted, but I'm using them panel mounted and soldering wires to them is a total PITA. So I'm designing a little board that will mount have 6 MTA-100 header pads on it. One set of 3 is for straight connections between the headers and the switches/pot. The other has spots for resistors for each of the inputs after the header (some uses of pots and switches might require adding a resistor and I hate soldering wires to them and having them dangle from a pot!).

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Post by msprigings » Tue Oct 22, 2013 7:37 am

Is there some common component/symbol library for design spark?

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Post by CLee » Tue Oct 22, 2013 7:59 am

msprigings wrote:Is there some common component/symbol library for design spark?
You can import Eagle libraries into DesignSpark. It's a little complicated and I always forget how to do it, there's a tutorial on their web site.

Considering the price -Free, without size or usage limitations- it's a great piece of software. PC only, no Mac version though.

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Post by msprigings » Tue Oct 22, 2013 8:10 am

Yeah I found some eagle libraries but it seemed I needed some intermediate file from Eagle. Since I don't have eagle I'm not sure I'm able to create that file.

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Post by ucacjbs » Tue Oct 22, 2013 8:41 am

msprigings wrote:Yeah I found some eagle libraries but it seemed I needed some intermediate file from Eagle. Since I don't have eagle I'm not sure I'm able to create that file.
There is a free version of eagle available, perhaps install it for the conversion purpose?

This is a great thread. I've been using KiCad for schematic capture, but have yet to do PCB design. Given that DesignSpark will also integrate with LTSpice, perhaps I'll switch to that.

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Post by djthopa » Tue Oct 22, 2013 4:09 pm

I hear you. Im at that stage too.

Getting sick of stripboard and making traces. I have been cheking Eagle, but feel i need to spend some time with it.

I keep on telling myself the goal is to make things to make music. Im spending way more time soldering and debugging, than making any music.
Doesnt seem to trouble me either. So, lets learn how to make pcbs :)

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