# Custom PCB help please.



## vestureofblood (Aug 12, 2010)

Hi everyone,

I have been trying to get some custom PCBs made, but am having a rough time doing it. I have contacted several online companies but have had little luck with this. Some have responded but most either cant help me or the cost is too much ( like several hundred dollars just to get started).

What I need is very simple. I need a round PCB about .050 thick. With a diameter of .560. The back side can be blank and on the front it needs to have a solder pad in the center of it .450 in diameter with a .125 hole drilled at the edge of it. I need to have a lot of them so making them by hand from blank PCB board is not an option.

Here is a picture of what I need.




I would like to have about 25-50 of them to start with.

Any help is appreciated 

Thanks.


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## wyager (Aug 12, 2010)

Have you tried batchPCB or any of those hobbyist PCB services? Maybe you could get a stock square PCB and grind it down yourself-PCBs are really easy to trim down with a bench grinder.


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## Torque1st (Aug 13, 2010)

First off a standard PCB is 1/16" thick. What PCB material do you need? Do some reading on the web about PCB design and manufacturing. Start your design with that. Find a friend with a CAD system that can design your board with a file output the PCB companies can use. I am not certain what they use nowadays. You also need tolerances on the hole size, position, pad size, position, and outer diameter. They can fabricate a panel with many parts on it but it will be up to you to break them out of the sheet and dress the edges.

Your minimum batch size on a part like that may be several hundred pieces. A lot of them will fit on one panel. They would most likely run several panels.

There are many PCB manufacturers in the KC and St Louis areas.


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## vestureofblood (Aug 13, 2010)

Torque1st said:


> First off a standard PCB is 1/16" thick. What PCB material do you need?


 
1/16" thick would be fine, I can make adjustments for that. As for material something that can handle a lot of heat.



Torque1st said:


> Find a friend with a CAD system that can design your board with a file output the PCB companies can use.


 
I dont have any of that kind of friends.




Torque1st said:


> You also need tolerances on the hole size, position, pad size, position, and outer diameter. They can fabricate a panel with many parts on it but it will be up to you to break them out of the sheet and dress the edges.


 
Tolerance would be about .005 on any of it.


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## PeaceOfMind (Aug 13, 2010)

Are the quotes you are getting maybe including the cost of them laying out a PCB board based on your drawing? PCB manufacturing is done from a specific type of file set (Gerber files) which specifies the design, including all it's drill holes, layer stack-up, etc. These can be output from any number of programs designed for the task of PCB design - in industry some notable ones might be PADS (Mentor Graphics) and Cadence OrCad. There are however some free ones that will suffice for your simple board - try expressPCB or EAGLE.

Things will be cheaper if you use standard board thicknesses and materials of course. It is not uncommon for there to be significant setup costs, or high costs for low quantities (less than hundreds of pieces), but there are still some cheap PCB manufacturers out there if you don't need quick turn or high tech services. These will be much easier to order from once you have a proper PCB layout/Gerber files, rather than just a drawing.


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## PeaceOfMind (Aug 13, 2010)

Also, I'll mention that I think you can layout your own PCB for something this simple, with a bit of research. Basically the process is you'll start by making an (extremely simple) schematic that has symbols for all of the board features (in your case just symbols for a couple of pads and a hole or whatever). You will then use one of the free/cheap layout tools I mention above to mechanically define the board and generate a set of Gerber files for manufacturers to use.


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## HarryN (Aug 13, 2010)

Quick double check on your design before giving you an answer on this.

A) Dimensions check
Radius of board =0.280 in
Radius of solder pad area = 0.275 in
Radius of centerline of the hole = 0.2125 in
Hole dia = 0.125 in

B) Use
- I assume this is a thermal spreader of some kind?
- Where does the heat need to go - sideways to another part, or physically through the board?

C) Back of board
- Is it acceptable for the back of the board to be conductive / copper plated?

D) Thermal Load
How much heat are we talking about here - 1 - 2 watts or more like 10 watts?

E) Soldering Questions
- Are you going to be surface mount soldering on this? I assume so.
- Lead based solder or lead free? Lead based solder melts at a lower temperature, so it is easier on the boards.

F) Rim area mask vs remove copper
Do you need copper actually removed from that rim, or just covered up with an epoxy that will keep the solder in that central area?

G) Hole in board
- I assume this is for passing a wire through it, or is there another purpose?
- Solder has a nasty tendency to leak down into that hole during the soldering process. Do you need a way to prevent this from happening? How much room do you have there?

H) Current load in the solder pad area
- Is there electrical current going through that solder pad, or is it just for heat distribution?
- If there is current going into it, how much?

You can respond to these by email to the adr I pm'd to you if you prefer.

Thanks

Harry


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## Th232 (Aug 13, 2010)

Harry's probably got you covered, but if he hasn't, PCBCart is where I do all my PCB stuff. Setup fee for something like that is pretty small if you spread it through 25-50 boards. Easiest way is to manually draw out a board on Eagle then send it off to them. They accept Gerber, Eagle and a couple of others.


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## fyrstormer (Aug 13, 2010)

There's a company that takes small circuit board designs from multiple customers and turns them into large single designs that they send to have manufactured, and then they break them down into their component boards again before mailing them to their customers. I don't remember the name of the company, but they were in an issue of IEEE Spectrum a couple months back so I'll look it up tonight.


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## Lyndon (Aug 13, 2010)

A couple of ideas. 

I know you said you "can't" do this yourself, but this is a very simple board and can be etched easily. Cutting a circle is likely to be the only difficult part and that part a machine shop could do easily.

If you don't want to etch it yourself, you could probably take it to a machine shop and they can mill out the annulus at the edge of the board and drill the hole for very little beyond a setup charge.

Does it have to be a PCB? You said the other side can be blank. What if the copper extended all the way to the edge? Could you just take a big sheet of blank board and punch out these disks if you had an appropriate punch? 0.560 doesn't sound like a standard fractional size, so you'd have to get a punch made and that would be expensive.

what if it was solid copper with a hole in it instead of PCB? Would that work? Then a sheet metal shop could do the job easily. Or alternately a copper bar could be turned down to 0.560 and then have 0.50 slices taken off.


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## PEU (Aug 14, 2010)

I can try with my cnc router, it should be doable, monday is holiday here in Argentina, if you don't have a solution by then I'll give it a try.


Pablo


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## PEU (Aug 17, 2010)

Here is the CAM for the PCB, how many do you want? 







I can make more or less bridges, your choice.


Pablo


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## vestureofblood (Aug 19, 2010)

PEU said:


> I can try with my cnc router, it should be doable, monday is holiday here in Argentina, if you don't have a solution by then I'll give it a try.
> 
> 
> Pablo


 


PEU said:


> Here is the CAM for the PCB, how many do you want?
> 
> 
> 
> ...


 
Hi Pablo,

Will your machine produce a perfectly round product? I am guessing that it is also automated?

What if we keep it simple. Say a standard thickness copper plated PCB .062 I think is standard thickness. Cut a .560 disc with a rim around the edge where the copper is removed, say .03. And the hole contacting the edge where the copper is removed at .0562.

If you are able to do this what do you estimate the price for 25-50 pieces?

Thanks for your assist.


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## PEU (Aug 19, 2010)

Yes its round but you will have to file the tabs out (1mm wide) they are there to prevent the board to fly away when its almost finished. PCB thickness is OK, here I can find the same thickness.

If you give me the OK, I cut the PCBs and snap a few pics of them, and maybe a video of the process 

Price? I don't have a clue, lets do the following, I cut 50ish (depending how I finally fit them on the 100x200mm bare pcb) you pay me $15 that only covers shipping from Buenos Aires + Bare PCB.

Then, when you receive the boards, you decide how much they are worth to you and buy me a flashlight of that value (let me choose the model please :nana 


Pablo


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## vestureofblood (Aug 19, 2010)

I certainly cant argue with that, send me your PP info and I will get the first 15$ to you.

Are there any lights in particular that you are looking for?

Please let me send you the revised spec for this. I have made some changes to the size of the hole etc. before you make the board. I can send you the new specs when I get home tonight.


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## PEU (Aug 19, 2010)

no problem, send me the file here or to pablou [at] gmail and I redo the CAM tomorrow, no need to send money now, let me do the boards and when they are ready and you see photos, you send me the $15 and I ship them.

Flashlight? dunno some McGizmo titanium  , joking, when you tell me what I will get I tell you what I want 


Pablo


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## vestureofblood (Aug 19, 2010)

Ok Pablo, I have sent an email with the attached file. I have also included specs for another part I would like you to take a look at. Thanks for you help.


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## PEU (Sep 2, 2010)

Finished a batch of 36, not sure if you need more. Only "problem" I see with these is that I milled a little too much around the copper pad, but besides this the pcb is fully functional and should work with no problems, but, if this is a problem please let me know.






Youtube video: http://www.youtube.com/watch?v=Ofv0sDBbio4


Pablo


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## vestureofblood (Sep 2, 2010)

Looks great to me, thanks again. I like the vid too.


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## vestureofblood (Sep 3, 2010)

........


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## PEU (Sep 6, 2010)

boards are in the mail 


Pablo


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## vestureofblood (Sep 14, 2010)

I got the PCBs today. These are fantastic. I have sent an email to you reguarding payment,

Thanks again Pablo


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