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Typical TO-220 FET thermal resistance, case-to-sink?

When power dissipation gets beyond the trivial, a TO-247, with its more centered hole and a big footprint, is a far better deal than the toy TO-220. Better yet is the version without the hole, whatever that is, clip mounted with no insulator. You can spend a little more on silicon and save a lot on heatsinks.

Decent thermal design is difficult, worse for transients. I prefer to build a mockup (cardboard and duct tape, with real heatsinks and fans, whatever) and either measure true Tj, or - more fun - test the parts to destruction and see how much margin we have.

I wish I could afford (and stand the learning curve of) some decent 3d thermal sim software.

John

Reply to
John Larkin
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The hole-free TO247/SC65/SOT429 is TO274. The TO264/SOT430 also has a hole-free version, but I've yet to run across a designator for it. TO220 and TO126 also had a number of hole-free versions in Europe and Asia (2-10T1A and SOT82/SOT194).

Semiconductor packages that have seriously addressed thermal interface issues generally either have the mounting 'screw' integrated into the body (ie stud), use multiple mounting holes that apply pressure to the mounting surface at equidistant points, or engage a clamping structure

- again usually with more than one clamp support position. These are more common in industrial RF or traction/inversion power devices.

You see the same principles applied in Japanese commercial plastic power parts like the M38, MT200 and HPAK/2-34H1A. All of these were ignored by 'western' industry, and continue to languish in limbo.

On the side of the ridiculous, multiple hermetic versions of the TO220 were developed for MIL and aerospace in the TO257 and TO265, which just shows how stupidity can be duplicated, in the process of quick and dirty design 'militarization' - though there already was a two-screw version in the TO254. Similar hijinks occurred with TO218 package sizes.

RL

Reply to
legg

I can't believe that either the cost or learning curve are out of your reach. Most of the effort is in creating the solid model of your parts, drawing in 3-D, tedious but not challenging. Take a look an

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Last I checked a multiphysics package with structural thermal and fluids capability was around $20k. Not sure how much extra the full wave EM solver is.

Reply to
Glen Walpert

Recently stumbled across a TO273AA package shape ( IR 'Super 220'), which is an overcast uninsulated TO220 without a mounting hole. Applied to mosfets and IGBTs, it claims 300W capability @Tc

Reply to
legg

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