are there any heatsinks which can be soldered with ordinary lead solder to a pcb copper pour?

 

hi p48,
There are various types available, which type are you searching for.?
https://www.google.com/search?q=PCB...gAhXuXRUIHdbuA80QsAR6BAgCEAE&biw=1648&bih=914

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ho,
Is the first item on this list close to the size you could use.?
https://alutronic.com/products/heat-sink-pcb-mounting
E

 

something small but big enough to solder on the back of a to220 tab or right onto an exposed copper pour.

It's more typical to use heatsink compound, screw, and nut to attach heatsinks to TO-220.

 

something small but big enough to solder on the back of a to220 tab or right onto an exposed copper pour.

these would work but they have adhesive https://www.ebay.com/itm/231974531000/

If you are looking for heatsinks specifically designed for TO-220-3s, they exist, and you use a nylon screw and nut to hold them on. You can use a thermal compound between the tab and the heatsink if you like, but most of the time I've found that unnecessary.

You can get them in quantity for less via other suppliers, but if you need 1 or 2, here:

https://www.jameco.com/z/507302B000...MIqM6TnKzw4AIVVwOGCh3T7An3EAQYDyABEgIOVPD_BwE

 

hi,
I have used a clip on type similar to this model.
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https://uk.rs-online.com/web/p/prod...VjbTtCh0VVgCdEAQYBCABEgLHX_D_BwE&gclsrc=aw.ds

 

I saw one design in which the engineer used a sheet of copper instead of aluminum to bring down the temperature rise. No solderability problems with that one.

 

Most aluminum heatsinks are anodized because it increases the emissivity coefficient from about 0.04 for bare aluminum to about 0.8.

 

are there any heatsinks which can be soldered with ordinary lead solder to a pcb copper pour?

Also, be aware that a heatsink isn't the whole answer. If this is a regulator for example, you're going to have to do a calculation to determine how much current you can actually output at a given voltage while keeping your junction temperature and overall dissipation within the range of specifications that you want.

 

Usually a heatsink is anchored to the circuit board, not just the TO-220 device, so that vibration does not break the leads off. There are heat sinks with two tinned steel tabs to solder to the board, they are usually found in older CRT displays and TV sets. Also some have a tapped hole for a screw and a few have channels in the sides for skinny self tapping screws. So there are a few options.

 

What I have done in the past is sandwich the devices between the board and a 1/8 aluminum mounting plate/heat sink, the nuts shown would be replaced by tapped holes in the plate.
It does take up a little more board real-estate however.
Max.

 

I saw one design in which the engineer used a sheet of copper instead of aluminum to bring down the temperature rise. No solderability problems with that one.

In my case, after applying the white thermal grease, a pop rivet was enough.

 

I don't know about today's TO-220 packages but I remember epidemic failures on a particular RCA plastic body power transistor because a stress spreading washer was left off in production. But a pop rivet....!

 

I don't know about today's TO-220 packages but I remember epidemic failures on a particular RCA plastic body power transistor because a stress spreading washer was left off in production. But a pop rivet....!

After checking that many times I could not see any sign of stress on the package. The pop rivet works just on the tab and it does not even touch the plastic package at all.

 

The concern is that it might warp and cause the die to detach.

Wait a couple of years and see what happens Then we will have a good idea whether the pop rivet is a problem or not.

 

What works very well and completely avoids that die-stress failure is a spring clamp bearing against the plastic portion of the transistor. I have seen it used a few times and I have used it myself. And it is described in one RCA application note.

 

were do they sell those tin plated heatsinks?

I have not purchased them, only pulled them out of scrapped computer monitors and TV sets. But having seen them I know that they exist. AND, mostly they are not plated, they have either solderable added posts crimped in or else they have as part of their shape, extruded in grooves that a screw can engage. Probably Arrow or Newark or one of the other major electronic parts sellers have them. But I never need a thousand so I don't look there.