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Panelizing PCBs, how do you do it?
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Panelizing PCBs, how do you do it?
Stab Frenzy
So I'm on to my second design now and looking for ways to get my costs down to get more PCBs in more people's hands (or backlogs) and I keep seeing options for panelizing PCBs on the fab houses' order pages. Does anybody (everybody) do this? What's involved?

Do I lay out the panel with multiple boards on it and then send them a big Gerber with it all on or do I just send them the individual Gerber and ask them to panelize it? Are there any tricks or tips I should know about? Should I just email them directly and ask all my questions of the factory themselves?

Would love to learn from the experiences that others have had with this, thanks in advance for your input.
fitzgreyve
In essence - you just assemble your "sub" PCB's into one layout and order it as a single PCB.

However, be aware that a lot of PCB houses will not allow grooves, slots, or lines of drilled holes to be used to easily provide a "snap off" to separate the PCB's , partularly in their low cost "prototype" services (read the small print for your chosen PCB house).

For low-cost, Most of them will only allow a line or separator on the silkscreen (the same as any other silk screen printing). I have done this - you then have to score the PCB deeply both sides and snap to separate - works but not ideal for big runs.

Most of the PCB houses will allow grooves or slots etc in their "production" sized runs (i.e. 50+ units) - again you would just assemble you "sub" PCB designs into one file, but add the required separators or "snap offs".
BugBrand
For my protos in Eagle I arrange several boards in one .brd file (you have to copy/paste with the schematic closed - and be aware that parts references will change if things have the same names). Space boards by 0.05", keeping their out-lines intact. Then draw 0.05" routing paths between and add snap-holes in suitable places. My regular proto place typical charges an extra $20 or so on top of proto price for this.
thx2112
I do the same. It took forever to figure it out but now it's easy and I look forward to the challenge of cramming as many projects as possible onto one PCB. I now have more SMD adapters and breakouts than I know what to do with!

The key is to delete the schematic so values don't change, use the "wire" tool on the dimension layer to create outlines (think of it as CAD), and add the smallest possible drill the board-house uses for holes to snap the board apart.

ezod
Dave Jones gives a pretty good overview as part of his EEVblog series on PCB design for manufacture.
Stab Frenzy
Thanks heaps guys, that info is exactly what I needed.
whoop_john
I have been using Elecrow recently, because they allow panelisation and profile cutting at no extra cost. Colours other than green are also no extra charge, although curiously they have a slightly discounted package for green (work that one out!). I tend to go for their 100mm x 100mm cheap board option.

I use Osmond PCB on the Mac, so I cannot comment about Eagle, but what I have done is define a library part called 'snapapart'. This has a few 0.5 holes with no pads and the profile around the snap sections on the mechanical layer. I can then place these where I think appropriate.

I then ungroup these into separate objects and join up the ends of the profile sections with straight lines. In the PCB shown here for an Electric Druid VCDO I made a slight undercut either side of bridges so that the board snapped flush rather than leave a small extended tag. In reality this was overkill - it is easy enough to trim or sand these if they bother you, they are quite small. I've not done undercuts on recent boards.

Just be aware that there will be a minimum profile cutter size, which I think with Elecrow is something like 0.8mm - they ask that any slots are at least 1mm wide. The board shown here has 2mm slots.

whoop_john
Stab Frenzy wrote:
…or do I just send them the individual Gerber and ask them to panelize it?

They will probably panelise it for you, but there will equally probably be a charge for this. I would do it yourself if you can.

I think I was reading on Elecrow's site that they will also do V grooves for snapping, but stipulate that V grooves should go right across the board in a single straight line, so not as versatile as using little bridges.

With Elecrow any closed lines will get milled around and any unclosed lines get V grooved. At least I think that is how it would work. Elecrow info here as a PDF see also the web page Q&As on Elecrow's PCB service
d.simon
the elecrow pdf mentions "strip of holes" - does that mean you can place arbitrary patterns of holes on the board to facilitate panelization?
"V-cut, Strip of holes, Bridge & Slot is ok "

IOW why not just use holes to pannelize however you want? will that work? I see the advantages to "bridge and slot" though. "strip of holes" would probably leave rougher edges.
whoop_john
d.simon wrote:
the elecrow pdf mentions "strip of holes" - does that mean you can place arbitrary patterns of holes on the board to facilitate panelization?
"V-cut, Strip of holes, Bridge & Slot is ok "

IOW why not just use holes to pannelize however you want? will that work? I see the advantages to "bridge and slot" though. "strip of holes" would probably leave rougher edges.

Some people used to use a row of holes to create snap off sections, to get around the rules of some of the cheap fab houses which didn't allow panelisation. This was easily spotted and usually thrown out as inadmissable. They are just saying they allow it, but don't think it is a very elegant solution, both in terms of look and ease of PCB layout, if you compare this to V slot or bridge and slot.

Also Elecrow by default plate every hole that has copper pads (unless you negotiate with them), so you would have to makes sure you specified holes without pads, or the copper and plating won't make a clean snap and leaves jagged edges with stray bits of metal.
andrewF
Here's a great guide for designing panelised PCBs
d.simon
whoop_john wrote:

Some people used to use a row of holes to create snap off sections, to get around the rules of some of the cheap fab houses which didn't allow panelisation. This was easily spotted and usually thrown out as inadmissable. They are just saying they allow it, but don't think it is a very elegant solution, both in terms of look and ease of PCB layout, if you compare this to V slot or bridge and slot.

Also Elecrow by default plate every hole that has copper pads (unless you negotiate with them), so you would have to makes sure you specified holes without pads, or the copper and plating won't make a clean snap and leaves jagged edges with stray bits of metal.


good point about plating - that would be a problem if trying to do snap off. I like the slot-bridge stuff too - definitely cleaner. I was thinking in terms of writing eagle scripts or something - there's probably a way to write a script to replace lines with regularly spaced holes. Not sure of the usage of that - maybe for weird patterns.

so why are bridges included in bridge-slot method? is it so the product still resembles a "single pcb?". What happens if some of the bridges break before they send it to you?
whoop_john
d.simon wrote:
so why are bridges included in bridge-slot method? is it so the product still resembles a "single pcb?". What happens if some of the bridges break before they send it to you?

You pay for a single board and they usually panelise up your job with other people's jobs - that is why the discount for 10cms x 10cms and 5cms x 5cms - they get a lot of them and can batch them cheaply. If you supply an unjoined set of boards then it's more work for them trying to decided whose bits belong to whom. They are electrically tested too, so keeping them in one lump saves handling.

In the case of the little red board I posted above, one board did split, but possibly after manufacture and during packing. I got all the separate bits. In fact I got 14 boards and only paid for 10. Elecrow will throw in any extras. My last two orders yielded 12 boards and the one before that 11.

Incidentally, Seeedstudio and Iteadstudio tend to put their own identity marker serial number on the silkscreen which may or may not annoy you (it will if it is a front panel), but so far I have seen none on Elecrow boards.
whoop_john
d.simon wrote:
good point about plating - that would be a problem if trying to do snap off.

Not really a problem, we are talking about holes the size of vias here. I do a double row of holes, which obviously leaves a horn on one side, depending on where the board splits. This I take off with top cutters. I tend to trim any tiny nibbles with a blade.

Here's a couple of boards I made for nixies tubes:

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