In the photo below there are four diodes mounted in pairs on metal plates.
These two pairs of diodes form a Diode Bridge rectifier.

I can find the diodes...but a Google search did not reveal a source for the metal plates they are mounted on.

Anyone know a source for these? Or maybe I'm calling them something different than they are commonly known by?

Thanks

 

You would have to make them. Tinned copper preferably for thermal conductivity.

 

Figure out what currents and heat you are dealing with and then use a standard bridge rectifier mounted on a heat sink. One way to do it.

 

The plates are acting as heat-sinks, and are likely unavailable as a standard part.

Something like this may work.

 

Do you have an old PC PSU? they will have those heat sink plates in a variety of shapes made from aluminum, and will have solderable riveted ends to attach to a board.

 

Figure out what currents and heat you are dealing with and then use a standard bridge rectifier mounted on a heat sink. One way to do it.

I'm not 100% sure, but I think they may have done it this way in order to use ultra fast diodes.
The specific diodes used here are UF202 (HER203 is substitute I think)
I looked at some KBU bridge rectifiers and couldn't find recovery time specifications.

But I think Ultra fast recovery time is why they were done like this. Comments?

 

The plates are acting as heat-sinks, and are likely unavailable as a standard part.

Something like this may work.

Thanks.
Yes, those should work. I'd just need to get busy with the Dremel to make the feet so I could solder them to the board.
A little surprised such plates aren't readily available because unless I'm mistaken, this type of 4 diode setup is not uncommon?

 

Thanks.
Yes, those should work. I'd just need to get busy with the Dremel to make the feet so I could solder them to the board.
A little surprised such plates aren't readily available because unless I'm mistaken, this type of 4 diode setup is not uncommon?

How about using an old copper penny? If you can find one. New penny is coppered zinc.

 

How about using an old copper penny? If you can find one. New penny is coppered zinc.

Obviously a UK version!

 

I'd just need to get busy with the Dremel to make the feet so I could solder them to the board.

A nibbler will make less mess.

These used to cost around $10:

You might be able to scrape the anodization off in spots on something like this:

Black bodies radiate heat more efficiently than bare copper.

 

this type of 4 diode setup is not uncommon

First time I've ever seen this - at least as best as I can recall.

Also don't understand the need for ultra-fast switching diodes. I'm seeing some rather large filter caps on the board; so are we rectifying a radio frequency? I've never seen that done before. But that doesn't mean it's not done - it might be. But then I'm thinking if it's radio frequency then wouldn't it be shielded? But hey! What do I know? Right?

 

You would have to make them. Tinned copper preferably for thermal conductivity.

I have some sheet copper out in the garage. Was here when I bought the house. I suppose one could use sheet copper the likes of which I have, and it wouldn't have the fiberglass PCB material to act as a heat insulator. At least I'm thinking the copper sheet will have better heat dissipation than a copper clad PCB.

 

Obviously a UK version!

Another idea, go to the hardware store and buy for a quid a copper pipe joiner.
Cut it down the center and fold it out flat. OR smash it down flat with a hammer.
I must have 30 or more new here with me right now that will never be used.

 

First time I've ever seen this - at least as best as I can recall.

Also don't understand the need for ultra-fast switching diodes. I'm seeing some rather large filter caps on the board; so are we rectifying a radio frequency? I've never seen that done before. But that doesn't mean it's not done - it might be. But then I'm thinking if it's radio frequency then wouldn't it be shielded? But hey! What do I know? Right?

This is the information I was looking at.
https://electronics.stackexchange.com/questions/323507/bridge-rectifier-4-diodes-vs-single-chip

Silicon diodes do not turn off instantly. As the voltage across the diode goes negative, current still flows in the reverse direction for a short time, until the charges stored inside the diode are cleared out. When this is done, the diode turns off.
Different diodes have wildly different recovery characteristics, as shown in this scope plot:

The current does indeed go negative (the "wrong" direction for a diode) for a time which is called "recovery time". The red one takes longer.

In a DC-DC converter, it is crucial to have a diode that turns off quickly. Imagine using good old 1N4001, with its recovery time trr=30µs in a DC-DC converter running at 200kHz (cycle time 5µs). It wouldn't even have time to turn off. It wouldn't work at all. This is why DC-DC converters use much faster diodes

 

Thanks for the suggestions. It really helped.
I think the winning combo is......

IC Chipset GPU CPU Thermal Heatsink Copper Pad Shim Size 20 x 20 x 1.2mm Pack of 20
https://www.amazon.com/gp/product/B00OUJQYCU/ref=ox_sc_act_title_2?smid=A3DEMN06T1PXVI&psc=1

And.......
Parts Express Nickel Plated Nibbling Tool
https://www.amazon.com/gp/product/B0002KRACO/ref=ewc_pr_img_1?smid=A309CVB9A2IXYG&psc=1

I really needed exactly 21mm in height...but I'll have to make this work.

 

Soldering the diodes to an aluminum heatsink is problematic, since aluminum is difficult to solder to.

 

This is sort of what I have in my garage. Plain copper sheet, no fiberglass to insulate the heat radiation from both sides of the copper sheet. Easier to trim and shape as well.

 

Another simple cheap solution would be to cut a required length of thin wall 1/2" copper pipe and squash with vice and/or hammer.
lube the centre with flux before squashing and this could then be heated for solder to flow between sides.

 

Un-sanded copper pipe doesn't like to solder, even with aggressive fluxes.

 

go to the hardware store and buy for a quid a copper pipe joiner.
Cut it down the center and fold it out flat.

That works too, but you're still cutting and shaping the copper. Sheet copper is already flat. All you have to do is cut it to the desired dimensions. You can even cut in some feet for soldering.