Box Header Tutorial: Pin 1, IDC Crimp and Unmating

Orientation before force

A box header looks symmetric. Pin 1, the shroud key and the silkscreen triangle must be one rule, shared by the harness shop and the SMT line.

Step 1 — match the part

• Pitch, pin count and mounting style must match the ribbon (10/14/16/20/26/34/40P are common).
• PCB pin 1, housing triangle and notch on the same side.
• Do not crimp 1.27mm ribbon into a 2.54mm plug.

Step 2 — crimp

Red edge to pin 1. Flat entry, one full press, latch the strain-relief cover. Inspect insulation displacement and pull-test to the wire gauge. Do not “tap it again” until the conductor is cut.

Step 3 — mate

Key to notch, push straight home. Tug the plug body, not the cable. If it only enters on a bias, stop — wrong key or pin count. Do not hammer.

Step 4 — unmate

Pull the plug by its sides. Never pull the ribbon. There is no long ejector; do not pry the shroud. Frequent mating or vibration belongs on an ejector header, not a stronger WI.

Junjia can supply keyed, pegged box headers and put pin 1 on the drawing for the cable house. Train on scrap boards, not on the production panel.