Author Topic: Ribbon Laser Bonding on PCB  (Read 1495 times)

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Offline KneidlTopic starter

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Ribbon Laser Bonding on PCB
« on: April 26, 2024, 05:18:56 am »
Hi, I am working on a project where we need multiple ribbon bonds attached to a PCB using laser welding.
The downside of the technology is that according to the machine manufacturer, the copper-tickness on the PCB-side must be at least 400µm.
As I would like to avoid any special PCB manufacturing process like copper-inlays, my idea was to just solder some tiny pieces/plates of copper or nickel on the top side and then the laser can weld to them.
But I cannot find something like a reeled 5x5mm (max. 15x7mm) copper plate on digikey, or at least I don't know in which part category I have to look for.
The closest thing I found to what I need are some shunt resistors (digikey: BVE-Z-R0001-1.0) , but the low resistive ones are too big or have a non flat surface and are in general kind of expensive.
Can someone tell me to what I should look for or maybe has a better idea to a rather cheap and mass manufacturable solution?

Offline Kean

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Re: Ribbon Laser Bonding on PCB
« Reply #1 on: April 26, 2024, 10:25:18 am »
I'm guessing these are too small... or as you say, not flat.

The largest seem to be 2.0x2.54mm, 1.7x3.0mm, or 1.8x5.5mm on top surface.  Maybe they could make something custom one for you.
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Online wraper

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Re: Ribbon Laser Bonding on PCB
« Reply #2 on: April 26, 2024, 10:38:35 am »
Dunno about 5x5mm but smaller ones are easily available
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Offline ajb

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Re: Ribbon Laser Bonding on PCB
« Reply #3 on: April 26, 2024, 06:22:11 pm »
What sort of volume?  And if you're looking at current shunts, I guess the surface doesn't need to be bare copper, but can be plated?

You could get whatever size and shape you want laser cut or stamped out of sheet metal.  Stamping can be very cheap if you've got enough volume to amortize the tooling/setup cost, and any company that does electronic stamping should be able to acquire pre-plated sheet coil, so they'd be ready for soldering after stamping and cleaning.  For assembly, you could probably get some custom plastic trays CNC milled, or maybe stacked out of laser cut sheets, to standard JEDEC sizes to go into a tray feeder.  Loading the trays from the bulk stamped parts might not even be too bad, if the wells are sized correctly you should be able to just throw a handful of parts onto them and shake until they settle into place.  Some assemblers may even be able to place loose parts out of tray wells, for example Europlacer machines have that as an option.

Offline tooki

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Re: Ribbon Laser Bonding on PCB
« Reply #4 on: April 26, 2024, 08:30:31 pm »
Somehow it seems silly to me to solder on targets for welding. Couldn’t you just solder the ribbons on at that point? (Selective laser soldering is a thing, too!)

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