EEVblog #974 - PCB Layout Walkthrough

[tautech]

Much enjoyed, once started couldn't stop watching. <rubbing eyes now> Nice to see some of the AD features being used to great effect. 

[mrpackethead]

Hi Dave,

I saw you struggling to get the 3d objects placed in the right orientation.. Theres a simple thing to do.
Tools -- 3D body Placement -- Align face with board.
in 3d mode you just click on teh face you want aligned with the board and it sorts out the orientaiton and standoff for you. :-)  Easy peasy.

Also Since you had so much repeatativeness in the circuit, you coudl have used some hyricheal sheet design.. these would end up being 'rooms' in the pcb, and then you only need to route out one, and copy the format from room to room.  On things that have so much repititon this can save hours!

[mash107]

Dave-- far be it for me to second guess you, but those resistors seem undersized for 160V (not Pd, as they are 22k in value, but dielectric withstanding).
You'll need a 1206 or larger I think: http://www.vishay.com/docs/20035/dcrcwe3.pdf

[EEVblog]

Dave-- far be it for me to second guess you, but those resistors seem undersized for 160V (not Pd, as they are 22k in value, but dielectric withstanding).
You'll need a 1206 or larger I think: http://www.vishay.com/docs/20035/dcrcwe3.pdf

They will never see 160V. You will always have the supply minus either the zener clamping voltage or filament voltage.

[EEVblog]

Also Since you had so much repeatativeness in the circuit, you coudl have used some hyricheal sheet design.. these would end up being 'rooms' in the pcb, and then you only need to route out one, and copy the format from room to room.  On things that have so much repititon this can save hours!

Not when you share chips between displays.

[DutchGert]

Nice video but I though you would put in a bit more 'pride' and nit picking into the layout and make it a bit nicer/teach the young ones some tricks.

Why not:
-use (almost) the same fanout on each tube
-set up proper design rules/classes for the high voltage stuff. Everything 8/8 but the HV stuff 15/15 for example.
-tidy up the schematic
-tidy up the silkscreen
-use proper 3D footprints for the IC's (Altium IPC wizards even generates those) and the module
-'direct connect' and don't use thermal relieves on via's and tent those while you are at it

I mean, it is a functional board but why not teach the new kids something more than just maken a functional board.

Like you said, pcb design is an art and it's ok to put a bit of effort and pride into it .

edit: I know it's a one off board but this video will be watch by >100000 people.

[Windfall]

Like you said, pcb design is an art and it's ok to put a bit of effort and pride into it .

This is what I am sorely missing too. This is hardly a demonstration of 'art', even if it doesn't really pretend to be (which it should).

[EEVblog]

Nice video but I though you would put in a bit more 'pride' and nit picking into the layout and make it a bit nicer/teach the young ones some tricks.
Why not:
-use (almost) the same fanout on each tube
-set up proper design rules/classes for the high voltage stuff. Everything 8/8 but the HV stuff 15/15 for example.
-tidy up the schematic
-tidy up the silkscreen
-use proper 3D footprints for the IC's (Altium IPC wizards even generates those) and the module
-'direct connect' and don't use thermal relieves on via's and tent those while you are at it

I mean, it is a functional board but why not teach the new kids something more than just make a functional board.
As for the nixie fanout, I mentioned that I addressed that in a previous comment.
As for tented ground vias, you don't always want those, as they can be handy for ground test points. yeah I know, put in ground test points too. The tweaks can go on forever...
Like you said, pcb design is an art and it's ok to put a bit of effort and pride into it .
edit: I know it's a one off board but this video will be watch by >100000 people.

It was never intended to be a tutorial, it was just supposed to be me screen capturing the layout and adding a few comments.
By the time I realised it was turning more into a tutorial kinda it was too late to go back and do many things more stringently as I'd do for a production board. It was alos getting very long.
I could add a dozen things to your list I could have done and talked about, you have to stop somewhere.

[casinada]

Did I miss the 0.1 uf  decoupling capacitor on each integrated circuit?

[rrinker]

 My only question is, wouldn't it be better to put the power jack on the back side as well, so that the only real thing projecting above the front would be the nixie tubes themselves? Seems that would make the mounting in a front panel be that much more flexible. Or is it that it just doesn't matter in this application, as we will see in a future video?

[Philfreeze]

If you want to make a 3d component with transparent parts in it you have to split the model.
Go into your CAD software of choice, open the step file and split it ito two step models, one with all the transparent stuff in it and one with the solid stuff.

I did exactly that already for you.
You will find a parts library with the two step parts already in them.
Alternatively you can place them by yourself. Just set the transparency of the bulb in Altium to 50% or so.
Additionally the part is oriented correctly to make the placement easier.
The only thing you will probably have to correct is the standoff height.

https://www.dropbox.com/sh/of6hdoe2dau3p5q/AACtShcnasLTcCttIhHl390Wa?dl=0

[Deridex]

Nice video but I though you would put in a bit more 'pride' and nit picking into the layout and make it a bit nicer/teach the young ones some tricks.
Why not:
-use (almost) the same fanout on each tube
-set up proper design rules/classes for the high voltage stuff. Everything 8/8 but the HV stuff 15/15 for example.
-tidy up the schematic
-tidy up the silkscreen
-use proper 3D footprints for the IC's (Altium IPC wizards even generates those) and the module
-'direct connect' and don't use thermal relieves on via's and tent those while you are at it

I mean, it is a functional board but why not teach the new kids something more than just make a functional board.
As for the nixie fanout, I mentioned that I addressed that in a previous comment.
As for tented ground vias, you don't always want those, as they can be handy for ground test points. yeah I know, put in ground test points too. The tweaks can go on forever...
Like you said, pcb design is an art and it's ok to put a bit of effort and pride into it .
edit: I know it's a one off board but this video will be watch by >100000 people.

It was never intended to be a tutorial, it was just supposed to be me screen capturing the layout and adding a few comments.
By the time I realised it was turning more into a tutorial kinda it was too late to go back and do many things more stringently as I'd do for a production board. It was alos getting very long.
I could add a dozen things to your list I could have done and talked about, you have to stop somewhere.

Your video is closer to a tutorial than quite a few "tutorials" i have seen so far.
It was quite interresting, even though i routed already quite a few boards already.

[ion]

Dave, you mentioned the possibility of swapping the software defined pins - that's a reason I prefer to mimic the physical chip when I make my own components.
I know you gave a reason for not doing that in a previous video, but sometimes you can see potential layout headaches while still working on the schematic.

[thm_w]

2. Vias: In my current 2-layer PCB design I have no additional vias, but everything is through-hole in my design so I am able to use the component holes as a via instead where needed.  I thought vias were considered to be a "last resort" type of thing and to be generally avoided due to the additional resistance each one adds to the circuit, but Dave uses them without too much concern in this particular design.  The sheer number of traces going between components also necessitates the use of vias in his case, but it is good to know that using vias is not really too much of a negative in basic DC/low current/low frequency PCB designs.  Obviously a high frequency design would need to be concerned about many more things than just vias.

Anyone saying to minimize vias in general is either an old-timer, or basing the suggestion off if you are lazy at layout you will often end up with an excess of vias. ie autorouting the board.
The resistance is minimal, but be sure to calculate if using them for high current traces: http://circuitcalculator.com/wordpress/2006/03/12/pcb-via-calculator/

Did I miss the 0.1 uf  decoupling capacitor on each integrated circuit?

Frequency is low enough it doesn't really matter, and he isnt trying to pass EMC.

[casinada]

I don't want to argue but it is recommended practice to add the 0.1uf decoupling capacitors on each chip. They're probably a penny each and don't take much real estate. There are lots of chips changing states all the time and the capacitors make sure that the supplied voltage at each chip stays as constant as possible.

[mrpackethead]

Dave, what was the logic behind not having decoupling caps?

[HSPalm]

Where do you find a manufacturer that has 8/8 mil track width/clearance? I think most, if not all, on PCB shopper is 6/6. And when they say they can handle it, is there any reason you should not trust it? I got the feeling that even though you set DRC to 8/8 you tried to avoid putting the tracks next to each other.

[DutchGert]

If you want to make a 3d component with transparent parts in it you have to split the model.
Go into your CAD software of choice, open the step file and split it ito two step models, one with all the transparent stuff in it and one with the solid stuff.

I did exactly that already for you.
You will find a parts library with the two step parts already in them.
Alternatively you can place them by yourself. Just set the transparency of the bulb in Altium to 50% or so.
Additionally the part is oriented correctly to make the placement easier.
The only thing you will probably have to correct is the standoff height.

https://www.dropbox.com/sh/of6hdoe2dau3p5q/AACtShcnasLTcCttIhHl390Wa?dl=0

Very nice trick and thx for the Lib, will use this in the future

[GekkePrutser]

Great video! I watched it all the way as I was just about to start on a project of my own (in Circuitmaker after I heard about it in one of your earlier videos - love the 3D thing). I could also have learned Eagle but I like your tutorials.

I was just wondering: Where did you get the WeMos D1 Mini footprint from? I am using the same module and I could really use it. I know I can make one myself but I'm afraid I'd mess it up It's already happened once that I measured something wrong and got a 3D print (bezel) produced and it didn't fit the screen At least I have my own 3D printer now so I can prototype.

PS: Yes I just signed up here to ask this but I'm a regular viewer of your video channel Just never got around to registering here.

[AF6LJ]

Thanks Dave, this was great...
Please do show the next steps, for those of us who do have long attention spans...

I've laid out a few boards the old fashioned way and here soon will attempt to do one the new fangled way.

[Macbeth]

It would be great if the final design is published on the free Altium CircuitMaker cloud open source thingy.

I mean that must be nice and easy to export Altium Designer files to, right?

[AlphaRomeo]

It would be great if the final design is published on the free Altium CircuitMaker cloud open source thingy.

I mean that must be nice and easy to export Altium Designer files to, right?

Altium Designer is the software used  for this video?

[thm_w]

Altium Designer is the software used  for this video?

Yes, Altium Designer 17, shows at the top.

[Nobody2]

While watching I was thinking how i might try lay out the board and make it nice looking.

1. Take a look at the nixi tube and make a layout with all traces in order
  b)  find a nice looking layout with all traces in parallel
2. if b change the pin order of the schematic model to avoid a messy schematic
3. make a layout for the shift registers to get all outputs in parallel and in order
After that connecting everything should be easy.

Btw, I was surprised how the hard the autorouter failed, especially when restricted to only a few connections.