Cable Assemblies Checklist

This checklist is designed to ensure electrical compatibility, assembly safety, and documentation integrity in cable assemblies (wire harness, cable sets, jumpers, connector interconnections). It particularly focuses on cable length, color coding, termination techniques, and mechanical fastening.

Wire and Termination Compatibility​

1. Is the wire gauge appropriate for each connection?​

Each connection line should be selected with appropriate wire gauge (AWG) for the current and voltage it will carry.

For example:

• Signal lines typically use AWG24–26
• Power lines use AWG20–18 or thicker
• Motor drivers or high-current circuits prefer AWG16 and below

Wire gauge must also be compatible with the type of pin, terminal, solder pad, or connector it connects to. Excessively thin wire can heat up due to current density causing insulation damage; excessively thick wire may not fit the terminal or create mechanical stress on the solder surface. Proper wire selection is fundamentally important for both electrical safety and mechanical durability.

2. Has mechanical compatibility with cable gauge been verified for each termination type?​

Cable terminations must be properly sized for the connection method used (soldering, crimping, socket). In soldered connections, pad or terminal hole diameter should be proportional to cable gauge. In crimp connections, the terminal's inner diameter and metal thickness must properly seat the cable; neither excessive clearance nor compression should exist. In socket connections, pin and female terminal inner diameters should be verified according to manufacturer tolerances. Additionally, mechanical pull test should be applied after crimping to verify connection breaking strength. This control directly determines reliability, especially in systems exposed to vibration or high temperatures.

Cable Routing and Fastening​

3. Are cable ties or lacing cords shown in necessary locations?​

Cable ties or lacing cords should be used at appropriate points in cable assemblies to reduce risks of bending, vibration, or surface abrasion. Assembly drawings should clearly mark these fastening points and specify the material type used (e.g., nylon tie, PTFE lacing). Especially:

• In moving systems, to protect cables against mechanical fatigue
• At corners, to maintain cable bend radius
• In vibrating environments, tie spacing should be defined to prevent cable friction

Tie spacing should typically not exceed 100–150 mm. Incorrect or overly tight cable ties can damage insulation and lead to long-term failures.

4. Are mounting points (holes, clips, clamps) for cable ties clearly defined?​

Mounting points for cable fastening elements should be planned considering mechanical connection points and areas away from electrical components. Assembly drawings should clearly show holes, clips, or clamps where cable ties will pass, and these should be included in the bill of materials (BOM). Fastening points can be defined by: mounting holes on PCB, fastening points on metal case, or 3D printed guide parts. This way, the cable follows a route that is both mechanically secure and accessible during maintenance. Incorrectly positioned fastening elements can eventually load the cable or create strain on connectors.

Cable Color and Length Information​

5. Is the length of each cable clearly specified?​

All cable lengths should be clearly shown in assembly drawings, measured from connector center to center. This measurement method ensures consistency independent of connector type. Unclear length information can create incorrect cutting, excessive tension, or loose cable loops during production. Cable lengths should be repeated on both the cable diagram and harness drawing. Each dimension should be given with ± tolerance value (e.g., "350 ±5 mm").

6. Are cable colors defined according to function?​

All cables should be defined with standard color coding according to the type of signal they carry.

Example color mappings:

• Red → +V (supply line)
• Black → GND (ground line)
• Yellow → Signal line
• Blue → Data line
• Green/Yellow → Protective earth (PE)

This color mapping should be completely consistent between schematics, cable diagrams, and assembly drawings. Not using the same colors for different functions in different systems prevents confusion during maintenance and testing. Color codes should generally be selected referencing IEC 60446 or DIN 47100 standards.

7. Is color sequence specified in cable harnesses?​

In harness sets containing multiple cables, the color sequence corresponding to each pin order should be defined.

For example:

This table should appear in both the connector diagram and cable harness drawing. Incorrect color sequence can cause pin swapping during production and potentially damage the circuit.

8. Are cable length tolerances (+/– mm) shown in drawings?​

When specifying cable lengths, length tolerance should be clearly written for each cable type. Particularly for short jumper lines, tight tolerances like ±1–2 mm can be critical. For long cables, tolerance can typically be given as ±1% ratio. This information prevents problems like post-assembly tension, pin strain, or excessive sagging. Tolerance values should be included in production drawings in agreement with the manufacturer.

Termination and Terminator Details​

9. Is the wire termination type and method clearly specified?​

The connection method for each cable end — soldering, crimping, compression, or socket connection — should be clearly specified in assembly drawings or notes. This information allows the assembly operator to directly understand which process to apply. Connection method should also be selected according to the cable's function and operating conditions:

• Soldering → small signal or low current lines
• Crimping → mass production and high vibration environments
• Compression or socket connection → ideal for modular or maintenance-requiring systems

Incorrect method shortens connection life or can increase contact resistance.

10. Is heat shrink tubing requirement specified for soldered connections?​

If heat shrink tubing is mandatory for electrical insulation and mechanical strength in soldered connections, this requirement should be clearly specified. The tubing's length, inner diameter, color, and material type (e.g., polyolefin) should be in production notes. Proper tubing use protects the connection against both tensile forces and environmental effects. It is recommended to specify in assembly documents as follows:

"Tubing: Ø4 mm → Ø2 mm, 15 mm length, black, 2:1 ratio, shrink at 120°C."

11. Are crimp force and tool type specified for crimped connections?​

In crimped connections, crimp force, terminal type, and hand tool or die to be used must be defined. For example: "Crimp force: 25 N, to be crimped with JST WC-110 pliers." Incorrect crimping force can cause both connection breakage and terminal loosening. After crimping, mechanical pull test should be performed and values kept in quality records. Additionally, crimping should be done with the terminal manufacturer's certified tools.

12. Are solder amount and technique specified?​

The amount of solder to be used in soldered connections, solder type (e.g., Sn60/Pb40, SAC305), and application technique should be defined. Brief descriptions like "just enough to wet the wire" or "enough to completely cover pad surface" make it easier for operators to take visual reference. Temperature profile should also be included in production notes to prevent cold solder, excessive solder, or solder bridge formation. This ensures assembly quality compatible with IPC-A-610 standard.

13. Are correct orientation and keying verified for connectors?​

Connector mounting orientation, key protrusion, and locking (latch) mechanism should be verified. In assembly drawings, connector orientation should be indicated with a clear arrow or reference symbol. Incorrectly oriented connectors can lead to faulty wiring or reverse polarity failures during production. In post-assembly testing, connector locking sound and mechanical seating should be checked.

14. If cable ends connect to ESD-protected components, are static precautions noted?​

If circuit components where cable connections are made are ESD sensitive, static protection measures should be taken during assembly. Assembly notes should include warnings such as: "This connection is ESD sensitive. Use antistatic wristband, grounding mat, and ionizer." These notes are mandatory especially for sensitive components like sensors, ADCs, FPGAs, MOSFETs, and communication interfaces (USB, Ethernet, RF). ESD control should be performed according to ISO 61340 or ANSI/ESD S20.20 standards.

Documentation and Control Notes​

15. Is there a pin-to-pin mapping table for each connection in the cable assembly drawing?​

Cable assembly documentation should contain a pin-to-pin mapping table showing all connections. This table should clearly specify connector pins at both ends, colors, and lengths for each cable.

For example:

This table is the basic reference during production and quality control. Missing or incorrect mapping can cause functional errors in cable assemblies.

16. Are connector types, manufacturer codes, and pin numbers written on the cable diagram?​

Each connector's model type, manufacturer part number (MPN), and pin layout should be specified in the cable diagram. For example: "JST PH-4, MPN: B4B-PH-K-S(LF)(SN), Pin 1 = VCC." This information prevents incorrect connector selection during procurement, maintenance, and production. Connector orientation (key) and latch position should also be marked in the schematic.

17. Is the tool, soldering station, or crimp pliers type to be used during assembly specified in notes?​

Equipment to be used should be clearly defined for assembly quality repeatability.

Example note:

"Soldering: Weller WE1010, 350°C, 1 mm Sn60/Pb40 solder." "Crimp: JST WC-110 pliers, 25 N crimp force."

Ambiguous equipment definitions can cause production errors and quality variations.

18. Is labeling and serial number policy defined for each cable assembly?​

Each cable assembly should be given a unique label and serial number for post-production traceability. Label format (e.g., W001, W002…) and placement should be shown in assembly drawings. Serial numbers should be linked to production batch and quality reports. This practice provides traceability in service and warranty processes.

19. If cable sleeve or spiral protection is required at cable terminations, is it specified?​

At cable ends or areas exposed to external factors, protective sleeve or spiral wrap should be used. This information should be noted in assembly drawings as "protection sleeve" or "braided sleeve." Sleeve type (e.g., PET, PTFE, PVC), length, and color should be specified. This protection is mandatory especially in heat, friction, or moving systems.

20. Are cable drawings and notes compatible with post-assembly inspection checklist?​

Cable assembly documents should be fully compatible with quality control (QC) inspection checklist. Control steps (color sequence, pin mapping, sleeve length, etc.) should appear in the same format on both assembly and inspection sides. This compatibility ensures quality inspections are completed fully and prevents field confusion.

21. Is UL-certified cable and terminal requirement specified (VW-1, FT1, etc.)?​

If the product requires safety standards, cables and terminals to be used must be UL certified. For example: information like "UL1007, VW-1 flame rating" or "FT1 compliant" should be in assembly notes. This requirement is a standard safety condition especially in industrial, medical, and automotive applications.

22. Are cable bend radius and strain-relief structure shown in drawings?​

Cable bend radius should generally be at least 5 times the wire diameter. This radius should be shown in assembly drawings or 3D models. Additionally, there should be strain-relief structure at cable connector exit. Incorrect bending leads to internal conductor breaks and long-term resistance increase.

23. Are cable assembly EMC shielding (braid / foil) requirements defined?​

For cables requiring EMI / EMC protection, braid or foil shielding type should be specified. Shielding connection points (e.g., case, GND pin) should be clearly defined. Additionally, if shielding drain wire exists, connection method should be added to documentation. Incorrect shielding causes noise coupling or signal loss.

24. Are connector locking (latch) and keying verified?​

Connector locking mechanisms and keying should be physically verified. In assembly drawings, each connector's orientation, latch direction, and seating position should be clearly marked. Incorrect orientation can cause circuit damage or faulty test results post-assembly.

25. Are cable labels associated with barcode / serial number?​

Labels on cables should be matched with barcode or serial number in the production database. This way, each cable assembly becomes digitally traceable with test results and production batch. Barcodes should be produced with durable and heat-resistant label material (e.g., polyimide).

26. Has harness test fixture and pin-continuity plan been created?​

A test fixture (test jig) and continuity test plan should be prepared for each cable assembly. Test plan should cover all pin-to-pin connections and specify "open / short" test limits. If automated test systems (e.g., Cami Research, Dynalab, Schleuniger) are used, software file version number should be added to documentation. This step eliminates human error during mass production and completes the quality assurance system.