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Method - TO220 to D2PAK transistor conversion

Problem

Logistics in obtaining electronic parts can be formidable. Often a direct replacement is not available in any sane price or timeframe, if at all. When one is lucky enough to find a similar part, asking for the packaging to match can be like asking for the Moon.

Solution

The TO-220 trough-hole package is often more available than the SMD variant, especially with brick-and-mortar stores. The equivalent surface mount version is D2PAK or TO-263.

D2PAK is mostly the same as TO-220. It differs by lacking the top part of the back wing with the screw hole, relying on being soldered to the board for heat removal, missing the middle lead that is connected to the wing, and different shape of the leads.

When all that's needed is a replacement part or two, a manual package conversion can be much less of a hassle than attempting to source the proper package.


Old and new comparison

Old and new comparison

The conversion begins with removal of the wing. The copper sheetmetal is scored deeply with a Dremel wheel; this produces a lot of heat. Holding the part in bare fingers helps with gauging this and prevents overheating of the part.

The scored wing then can be cut off with a pair of wire cutters, and the fracture surface smoothed with the Dremel wheel. Other cutting methods including a small hacksaw are also possible.


Dremel cutting

Dremel cut

Top side cut off

Top side cut off

Top side cut off

Top side cut off

The middle lead has to be cut off. The leads have to be bent to match the D2PAK shape. A pair of tweezers is handy to hold the lead next to the package, to avoid overstressing the plastic and to force the right distance of the bend. The second bend then can be done in a similar fashion.


Lead bending

Lead bending

The leads then have to be trimmed to match the D2PAK length.


Old and new comparison, front

Old and new comparison, side

Old and new comparison, wing top

Old and new comparison, back

The part then can be soldered to the board, replacing the failed or suspect one.


After soldering

After soldering

Opposite conversion

The conversion should be possible the other way as well, although that would be more laborious. The D2PAK can be soldered to a copper board, serving as a heatsink attachment and heat spreader. The leads, if too short to reach the holes, can be lengthened. The middle lead can be either attached to its stub, or to the wing or the heat spreader.


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