How long are the screws in TO-220 / TO-247 power semiconductor heatsink mounting?

The records range from 6 to 10 mm depending on the position, so match each screw to its own hole.

What is the thread pitch of an M3 screw?

0.5 mm (coarse), which is the standard pitch for M3 machine screws; a 0.35 mm fine pitch exists but is uncommon. The tap drill is 2.5 mm and the normal clearance hole is 3.4 mm.

What screwdriver do I need for TO-220 / TO-247 power semiconductor heatsink mounting?

The sources do not name the drive. For M3, Phillips heads normally take PH1 and Torx heads T10; socket heads take a 2.5 mm hex key.

Can I use an imperial screw instead of M3?

No. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3. Use a true M3 screw so it does not cross-thread or strip the hole.

Where can I buy replacement screws for TO-220 / TO-247 power semiconductor heatsink mounting?

TechSpareWarehouse (our own store) lists M3 x 6mm, M3 x 8mm and M3 x 10mm, which match lengths in the records above.

TO-220 / TO-247 power semiconductor heatsink mounting screw size

M3 · 6 to 10 mm long

Our records put TO-220 / TO-247 power semiconductor heatsink mounting on M3 screws in lengths from 6 to 10 mm.

The record covers mounting guidelines for TO-220/TO-220F/TO-247 packages specify the standard M3 mounting screw and torque.

This entry is marked reported and comes from aosmd.com.

M3 means a 3 mm nominal diameter with a 0.5 mm thread pitch. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3.

TO-220 / TO-247 power semiconductor heatsink mounting screw specifications

One row per fitment record. Head, drive are shown only where the source states them; pitch is the ISO coarse pitch for the thread.

Thread	Length	Pitch	Head	Drive	Where it goes	Status
M3	6–10 mm	0.5 mm	not stated	not stated	Mounting guidelines for TO-220/TO-220F/TO-247 packages specify the standard M3 mounting screw and torque	Reported

Fitment records and sources

M36-10mm typicalreported

Mounting guidelines for TO-220/TO-220F/TO-247 packages specify the standard M3 mounting screw and torque

pitch 0.5 mm · tap 2.5 mm · clearance 3.4 mm · PH1 / Torx T10

Source

How to check the screw before you buy

If several screws hold the same part, check that they are all the same length before assuming they are.
Diameter: across the threads an M3 screw measures about 3 mm with calipers (usually a hair under). If yours measures noticeably more or less, it is a different thread.
Pitch: 0.5 mm from one thread crest to the next (20 crests per centimetre). A thread pitch gauge or the pitch-gauge tool settles it in seconds.
Length: measure from under the head to the tip for pan, button, wafer and cap heads; countersunk (flat) heads are measured overall.
The records span 6–10 mm, which means different positions take different lengths — match each hole to its own screw.
Driver: the source does not name the drive. Standard M3 heads take PH1 for Phillips and T10 for Torx, and a 2.5 mm hex key for socket heads; a bit that fits loosely will cam out and strip the head.
Tightening: no device-specific torque is published in these records. The site's general figure for M3 is about 80-130 N·cm into metal threads and 35-60 N·cm into plastic bosses; snug it up and stop.

Common mix-ups with M3

Eurorack is a strong known case with two competing metric standards (M2.5 for Vector rails, M3 for Schroff/DIN-style and 3U threaded rails); mixing rail types requires matching screw/nut thread.
Printer manuals often mix screw callouts like 'M3*8L' (length in mm after the L) with driver-bit-only references elsewhere in the same manual — only the explicit M-prefixed entries were captured here.

Pitch gauge · Screw size finder · Torque guide

Buy these screws at TechSpare Warehouse

In stock and shipped from South Carolina. Our black screws are Phillips wafer head (low profile); match the head style and length to the original before you order.

M3 x 6mm Replacement Screws for XLR Audio Connectors Phillips Wafer Head 50-Pack $4.99
M3 x 6mm Phillips Wafer Head Carbon Steel Machine Screws for XLR Audio Connectors | 50-Pack (Black) $4.99
M3 x 8mm Screws for Leather Spike Attachments Guitar Straps 10-Pack $4.99
M3 x 8mm Phillips Wafer Head Screw for SLA Resin 3D Printer VAT Film - Single Replacement Black $0.10 each · min. 50
M3 x 10mm Phillips Wafer Head Screw for Sim Racing Wheel Paddle Shifter - Single Replacement Black $0.10 each · min. 50
M3 x 10mm Phillips Wafer Head Screw for RC Car/Truck Chassis Mount - Single Replacement Black $0.10 each · min. 50
M3 x 6mm Phillips Wafer Head Screw for 3D Printer Frame Assembly - Single Replacement Black $0.10 each · min. 50
M3 x 6mm Phillips Wafer Head Screw for Boutique Guitar Pedal Enclosure - Single Replacement Black $0.10 each · min. 50

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The same screw also fits

Devices whose records share a thread with TO-220 / TO-247 power semiconductor heatsink mounting, closest length match first.

NBK cleanroom/semiconductor vented socket head cap screw (SVSHT-M3-SD) also M3 × 6–10 mm
DIN 965 / ISO 7046 countersunk Phillips screw also M3 × 6–10 mm
DIN 912 socket-head cap screw also M3 × 6–10 mm
Sonos One power receptacle also M3 × 6 mm
Metcase Technomet-Control instrument enclosure also M3 × 6–8 mm
Eurorack modular synthesizer cases also M3 × 6–10 mm
Wooden Camera 153200 SSD Guard (RED SCARLET) also M3 × 8 mm
Meade LX200 Barlow / eyepiece retaining screw also M3 × 6–8 mm

Questions about TO-220 / TO-247 power semiconductor heatsink mounting screws

What size screw does TO-220 / TO-247 power semiconductor heatsink mounting use?: M3 × 6–10 mm for mounting guidelines for TO-220/TO-220F/TO-247 packages specify the standard M3 mounting screw and torque.
How long are the screws in TO-220 / TO-247 power semiconductor heatsink mounting?: The records range from 6 to 10 mm depending on the position, so match each screw to its own hole.
What is the thread pitch of an M3 screw?: 0.5 mm (coarse), which is the standard pitch for M3 machine screws; a 0.35 mm fine pitch exists but is uncommon. The tap drill is 2.5 mm and the normal clearance hole is 3.4 mm.
What screwdriver do I need for TO-220 / TO-247 power semiconductor heatsink mounting?: The sources do not name the drive. For M3, Phillips heads normally take PH1 and Torx heads T10; socket heads take a 2.5 mm hex key.
Can I use an imperial screw instead of M3?: No. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3. Use a true M3 screw so it does not cross-thread or strip the hole.
Where can I buy replacement screws for TO-220 / TO-247 power semiconductor heatsink mounting?: TechSpareWarehouse (our own store) lists M3 x 6mm, M3 x 8mm and M3 x 10mm, which match lengths in the records above.

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