SOP: Close and screw (sta:a4)

SYNTHETIC example. Rev C, 2026-10-14.

Operators: 1
Equipment: closing fixture, electric torque driver, 0.18 N·m, with count check

Steps

1. Close top sub-assembly onto the core (op:close). Align at USB-C end, rotate closed. Target 8 s.
2. Drive four M2 screws to 0.18 N·m (op:screw). Torque driver, cross pattern. Target 16 s.

Watch for

• Route the battery wire inside the rib channel before closing. Never across a top-shell boss path.
• Drive the screws in a cross pattern.
• The driver must report four good torques before the unit moves on.

Risks at this station (PFMEA)

• Battery wire pinched between shells: RPN 90 (fm:pinched-wire)
• Screw strips the boss: RPN 45 (fm:screw-strip)