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10. Practical Selection Checklist

Use this at work. Adapt to your program; it is a working checklist, not a standard.

Interface definition

  • What subsystem boundary is this?
  • Internal or external?
  • Technician-serviceable or factory-only?
  • Must it be disconnected under power?
  • How often mated/unmated over service life?
  • Is wrong mating dangerous?

Electrical

  • Voltage rating + transients/peak checked
  • Current per contact at temperature checked
  • Bundle/thermal derating applied (use a conservative margin and the manufacturer derating curve)
  • Rating source (document + revision) recorded for the voltage/current values used
  • Loaded-contact count, ambient temperature, termination type, allowable temperature rise, and margin rationale documented
  • Wire gauge compatible with contact barrel
  • Signal type identified; high-speed/RF flagged
  • Shield strategy documented — type, termination points, and rationale (one-end vs. both-ends vs. 360° backshell is system- and frequency-dependent, not a universal rule)
  • Power and signal segregation considered
  • Load-break / hot-plug / mate-under-power status recorded from the datasheet (yes / no / explicitly prohibited / not specified — never assumed)
  • For power interfaces: touch safety when unmated, fuse/overcurrent protection, available fault current, and inrush/precharge documented
  • Spare positions added where feasible and justified (and sealed/documented)

Mechanical / environmental

  • IP rating verified for the complete assembly
  • Mated and unmated (capped) sealing considered
  • Vibration/shock requirement and locking matched
  • Cable strain relief defined; backshell selected
  • Cable jacket OD compatible with gland/clamp
  • Wire seal range matches wire OD; unused cavities plugged
  • Bend radius and cable exit angle checked
  • Panel thickness/cutout checked
  • Mating sequence (ground-first) considered for hybrids, where available
  • Torque specs identified
  • Dust caps / dummy plugs on BOM

Manufacturing

  • Crimp contacts and correct crimp tool identified
  • Positioner/die and insert/extract tools identified
  • Assembly instructions + inspection criteria defined (acceptance per IPC/WHMA-A-620 or the program/customer equivalent)
  • Pull-test / continuity test plan defined
  • Supplier availability and lead time checked
  • Second source / QPL considered

Documentation / configuration control

  • Connector, mate, contact, backshell, cap, gasket part numbers
  • Pinout table + cable drawing + harness drawing
  • ICD entry written
  • Key position unique across differing pinouts
  • Rev-controlled BOM + labeling scheme

Before sign-off, scan What People Forget for the items most often left off. For a fully worked pass of this checklist against one interface, see the Connector Selection Packet example.