[Solved] Repair: replacing heatsinked high power TO-220 with D2PAK?

[llkiwi2006]

Hi,

I am working on repairing an audio amplifier that uses two LM4752 in through-hole TO-220 package vertically mounted to a big aluminium heatsink. The chips have blown and I could only find replacements in surface mount D2PAK package, so I wanted to ask what is a good way to mount the D2PAKs to the heatsink? The amplifier is rated that each of the chips could output 15W of power, so good heatsinking is essential. I was thinking along the lines of somehow gluing them to the heatsink while maintaining good thermal contact, and then just soldering wires to connect each individual pin to the pcb.

Thanks in advance.

[gasmeter]

Hi

Whatever you do you need good thermal contact.

It's a To-263 package as you say similar to Dpak

Options are ...
Thermally conductive aryldite if you want to glue it.
A good option would be a thermal pad or grease and make a small aluminium block / clamp to adapt it to your heatsink mechanics.
You could also cut a copper rectangle, solder the device to it then voila you have a pretend To-220 package. (Preferred option I think)
Just bear in mind every mechanical interface point has thermal resistance.

I hope that helps.

Peter

[llkiwi2006]

Thanks gasmeter.

I found some 15mmx15mm copper plates on ebay for cheap, so I'm going to order some and see how well soldering the D2PAK chips to them works.

[langwadt]

D2PAK is basically a TO220 with the mounting hole cut off. Clamp it to the heat sink with something similar to this
https://media.rs-online.com/t_large/RD504059-01.jpg

[llkiwi2006]

For anyone curious, here are some pictures of what I ended up doing. Soldering leads to the legs proved to be the most painful (literally burning my fingers ). I used some thinner (awg30) wires for the second one, and that turned out to be a lot easier to solder and insert into the board. Overall I'd say it worked pretty well.

[Rog520]

Sorry to be a late reply on this one, but the LM4752T (TO-220) shows availability here (Canadian source):

https://www.componentonline.com/search?search_key=LM4752T

And a couple of ebay sellers list them, too.

[llkiwi2006]

Sorry to be a late reply on this one, but the LM4752T (TO-220) shows availability here (Canadian source):

https://www.componentonline.com/search?search_key=LM4752T

And a couple of ebay sellers list them, too.

Thansk for your help anyway. For me I would've just been a lot more costly to try get the obsolete (TO-220 version) part and get it shipped to NZ. In the end I think my DIY solution worked quite well (see a previous reply for pictures).