PT 3.5 / WN1412 3.5 self-tapping screws

Watch out for

• Often requires high driving torque; risk of motor stall on assembly lines
• Boss diameter must be 7mm minimum for PT 3.5
• Phone, console, router, drone and vacuum teardowns almost always publish only driver type and length, not the thread-forming size. Fastener makers (EJOT Delta PT, Plastite/WN1412, Covestro plastics guides) publish sizes 1.6-10 mm with pilot-hole tables instead, so size the screw from the boss hole, not from a parts listing.