Looking for pcb manufacturer who can create pcbs with copper buss bars

[mrpackethead]

I'm wanting to investigate PCB's that are created with inbuilt bus bars for carrying very high currenets ( >300A ). ( its low voltage, for a spot welder )...

Does anyone have any suggestions of a manufacturer of such things?

[twospoons]

PCBway can do copper up to 13oz (0.45mm) but that gets expensive fast.  A better way might be getting thicker copper or brass sheet machined to shape (etch, mill, laser, waterjet - many options) and solder/rivet/bolt that to your PCB.

[Psi]

You probably don't need the thickness of copper you think you do.
For a 300A spot welder PCB track heating isn't really a big issue since the duty cycle is usually really low.
You just need to be sure you're not going to lose too many volts/mV across the PCB. But you can use a higher input voltage to counter that.
I have a 6 layer 3oz pcb that can do 12V 150A for 30sec and the fets get a little warm but the PCB tracks carry 150A do not.
I reckon my PCB could do 300A for 1 second with no problems.

You will need a way to get this 300A into the PCB and out of the PCB.  I use press fit M6 terminals for 150A and they are rated to 250A i think.
But they make them for higher current too. And since you're only doing pulses you could probably use a terminal rated lower than 300A anyway.
Google image search "press fit pcb terminal" to see what i mean.

You need to spec the holes as press-fit with the pcb fab and provide them the info from the datasheet so they know the tolerances.
Then you need an arbor press to push them in and maybe a steel backing plate with holes cut out of it so it can sit flat and provide a surface to push against.  You can push them in with a vice for a one-off project if you can find a good way to push safety on the back of the PCB, but a $100 arbor press is way better.
Alternatively you can just have lots of sticking vias between layers in a location where you solder some thick wire directly to the PCB.
But that is annoying if you have to do lots of them. You need a very high wattage iron.

[mrpackethead]

I'd likely use SMT Mount Terminals,  ( theres a good selection of them )..  I have vapour phase soldering, and its perfect for this kind of thing.
8oz-12oz copper may well be enough.

[Doctorandus_P]

As far as I know, the bus bars are not a part of the PCB manufacturing process, but they are just parts that are placed on footprints.

And you can buy some standard models bus bars, have them custom made, or just solder some extra thick copper wire to the PCB.

[mrpackethead]

Ive seen pcbs with litterally solid chunks of copper in them!   pcb thats 4mm thick...  Just dont' know where to buy them.

[coppercone2]

300 amp is low for a spot welder.

You want like 1000+ amps

[Warhawk]

Ive seen pcbs with litterally solid chunks of copper in them!   pcb thats 4mm thick...  Just dont' know where to buy them.

Yes, this exists. We used it at work. I can find out who did it for us. However, if you're talking about a home/hobby project then just find another way.  It is expensive. I mean expensive. Very.

edit: Some time, I did something like this: https://www.ti.com/tool/TIDA-01168
It is not perfect but sufficient for a lab prototype. You can get a CNC-milled copper somewhere and then solder it on the PCB. I have more designs like this with custom copper busbars and WE Power elements
https://powerelement.we-online.de/?lang=en

[mrpackethead]

overnight i did find a coupel of possible supply choices, but as you say. its expensive.  Well, for low volume jobs anyway.    At volume it would make more economic sense than machining parts, but you'd have to be making > 200 units to make it viable.

[twospoons]

At volume I'd be die punching sheet and riveting/soldering that to the PCB. Thats always going to be cheaper than non-standard PCB processes. Because you can punch and form the sheet in one operation it opens up other possibilities - such as creating high current off-board connections that don't have to be in the same plane as the PCB.

[Psi]

300 amp is low for a spot welder.

You want like 1000+ amps

Probably depends on what you are spot welding.  Jewellery vs Cars   

[coppercone2]

I guess it depends on how you use it too, I am imagining pulse welding. If you are just doing long time welding then its different .

[Infraviolet]

If you're planning on a "attach cut copper to PCB" solution, you might do better to look at places which can do custom laser cuts of copper sheeting rather than milling. By definition you'll only need a 2D part, of whatever thickness is appropriate, so you don't need the geometric complexity milling can support. Copper is, I was told this when ordering laser cut steel, a bit odd to cut, in that a laser which can cut really thick hardened steel only manages a few mm of copper thickness before getting thermal weirdness affecting the cuts, but plenty of places can still do it. Laser cutting shops will be a lot cheaper than milling shops, the machine runs faster and needs less human effort to convert from your dxf file of the job in to code the machine actually executes. If you really want the mechanical shape of a board with a piece of copper inside it, you could always try making a board with cutouts where the big copepr piece will sit, then after placing the laser cut copepr piece there, consider maybe even sandwiching that board rom above and below with thinenr PCBs, providing you can do so in a way that leaves space for whatever you connect your high current in[uts and outputs to the copper with.

[Psi]

I would just make a 6 layer 3oz pcb and see how well it works.
The first PCB is usually never the final one, and you want to avoid doing all your testing on a very over-designed PCB and then having to do it all again to try and reduce cost later on because the over-designed board is so expensive.

Even if you get the pcb and it turns out the copper isn't thick enough, you can scratch off the solder mask and solder on your own copper plate/wire to get it working so you can continue RnD/Dev using the board until you can order a newer, thicker, more expensive one.  At least at this point you know that you do need that.

[langwadt]

If you're planning on a "attach cut copper to PCB" solution, you might do better to look at places which can do custom laser cuts of copper sheeting rather than milling. By definition you'll only need a 2D part, of whatever thickness is appropriate, so you don't need the geometric complexity milling can support. Copper is, I was told this when ordering laser cut steel, a bit odd to cut, in that a laser which can cut really thick hardened steel only manages a few mm of copper thickness before getting thermal weirdness affecting the cuts, but plenty of places can still do it. Laser cutting shops will be a lot cheaper than milling shops, the machine runs faster and needs less human effort to convert from your dxf file of the job in to code the machine actually executes. If you really want the mechanical shape of a board with a piece of copper inside it, you could always try making a board with cutouts where the big copepr piece will sit, then after placing the laser cut copepr piece there, consider maybe even sandwiching that board rom above and below with thinenr PCBs, providing you can do so in a way that leaves space for whatever you connect your high current in[uts and outputs to the copper with.

pcb shield are often made by etching

[Warhawk]

If you're planning on a "attach cut copper to PCB" solution, you might do better to look at places which can do custom laser cuts of copper sheeting rather than milling. By definition you'll only need a 2D part, of whatever thickness is appropriate, so you don't need the geometric complexity milling can support. Copper is, I was told this when ordering laser cut steel, a bit odd to cut, in that a laser which can cut really thick hardened steel only manages a few mm of copper thickness before getting thermal weirdness affecting the cuts, but plenty of places can still do it. Laser cutting shops will be a lot cheaper than milling shops, the machine runs faster and needs less human effort to convert from your dxf file of the job in to code the machine actually executes. If you really want the mechanical shape of a board with a piece of copper inside it, you could always try making a board with cutouts where the big copepr piece will sit, then after placing the laser cut copepr piece there, consider maybe even sandwiching that board rom above and below with thinenr PCBs, providing you can do so in a way that leaves space for whatever you connect your high current in[uts and outputs to the copper with.

To my knowledge you can't cut copper with laser. For this reason they use either water jet stream (enough edges) or CNC milling

[tszaboo]

https://datasheet.datasheetarchive.com/originals/crawler/we-online.com/277dd44227e09558ca863c0d9a1cc815.pdf
It's expensive setup costs, and not sure how worthwhile for large numbers. For production boards even for 1000s of boards we were using nickel plated copper busbars.

[langwadt]

If you're planning on a "attach cut copper to PCB" solution, you might do better to look at places which can do custom laser cuts of copper sheeting rather than milling. By definition you'll only need a 2D part, of whatever thickness is appropriate, so you don't need the geometric complexity milling can support. Copper is, I was told this when ordering laser cut steel, a bit odd to cut, in that a laser which can cut really thick hardened steel only manages a few mm of copper thickness before getting thermal weirdness affecting the cuts, but plenty of places can still do it. Laser cutting shops will be a lot cheaper than milling shops, the machine runs faster and needs less human effort to convert from your dxf file of the job in to code the machine actually executes. If you really want the mechanical shape of a board with a piece of copper inside it, you could always try making a board with cutouts where the big copepr piece will sit, then after placing the laser cut copepr piece there, consider maybe even sandwiching that board rom above and below with thinenr PCBs, providing you can do so in a way that leaves space for whatever you connect your high current in[uts and outputs to the copper with.

To my knowledge you can't cut copper with laser. For this reason they use either water jet stream (enough edges) or CNC milling

you can laser cut copper, but you need fiber laser not CO2

[thm_w]

There are hundreds of pre-existing low voltage spot welder designs: https://www.aliexpress.us/item/3256805429183735.html

Why do you need to do it a different way.

[mrpackethead]

There are hundreds of pre-existing low voltage spot welder designs: https://www.aliexpress.us/item/3256805429183735.html

Why do you need to do it a different way.

Because the vast majority of them are really one time smoke machines that go 'puff'..  They dont' deliver consistent results.

[thm_w]

They are based on this design which is reliable: https://gridrewired.com/products/kweld-spot-welder-kit

Any that fail would likely fail due to either poor FETs from cost cutting, or a circuit design issue (poor gate drive, etc.). Consistent results will require a suitable power source.

[mrpackethead]

The kweld is a good design, no doubt about that. Unfortunately its global distribution model is not nearly as good.  And by the time I can get one, its just not worth it.  And its an interesting thing to build somethign new.

So, I'm going to create an 'lweld'.  ( l comes after k. ).  The concept of a constant energy delivery is very solid.  Simple timing is not enough to get reliable operation.      The question of how you deliver constant energy is key to everything.

The Kweld is measuring voltage drop,  which provides a measure of currnet.   Mathematically, you can then derive energy,  as  Power x time..  Obviously the Microprocessor and A/D needs to be doing this pretty quickly, and making a LOT of measurements, in order to get resonable accuracy.     

The actual amount of energy being delivered is not really important.. We just want to be able to deliver the 'same' amount..   so, you can do some experiemental welds, and adjust up and down till dial in on the right weld.   

I dont' want to use batterys for my power supply, I'm intending on use super caps for the job..      Super caps have some interesting charactertics about them, but something we can exploit is the voltage drop between the start of the weld and the desired end of the weld.      This is a job for a comparator.. with a variable set point.   It requires that the SuperCaps are recharged back to the same voltage between charges.      There are jobs that sometimes where an analog solution  is a good fit..    I may have a microprocessor in the mix. but it will be more or less in a supervisory role, and not direclty controlling the weld switch off.

















HOwever its not the

[thm_w]

Absolutely, I am certain you can improve upon that design. But I still think you can do it within their original physical design constraints, with standard PCBs and busbars.

The welder I have is using two of these super caps, 1500F 5.4V total, probably overkill: https://www.aliexpress.us/item/3256804885148096.html
They seem fairly common as a surplus item, maybe pulled out of electric vehicles.

Please post some photos when you have a working setup.

[luudee]

Have you considered something like this:

https://atlee.com/bus-bars/


Good Luck !
rudi

[Neomys Sapiens]

I assume that you are looking for a local source? Europe, UK and US I would know several.
Maybe those guys would know, if you ask nicely? https://www.casa.co.nz/
I don't know if and where they are getting PCBs made or if they are doing it themselves. But they ought to know.