Wire conductors are available in many forms, ranging from single, solid insulated conductors, to highly integrated, multiple conductor cables.

Wires and cables can function as simple discrete jumpers on circuit boards, or woven into intricate harnesses that snake through a vehicle, functioning as the nervous system for the routing of command, control and signal impulses.

The correct preparation of conductors will result in a termination of high quality and reliability.

PREFERRED

CHEMICAL STRIPPING PROCESS

The insulation jacket has been neatly removed, with no damage to the conductor or insulation. No wicking of stripper or cleaner agents evident.

Note: Chemical stripping is suitable for solid conductors only.

PREFERRED

FLAT CABLE

The outer jacket, conductive shield (if supplied), and conductor insulation jackets have been neatly trimmed and removed, with minimal edge falsh and no mechanical damage. The conductors are in planar orientation, and the drain conductor and/or shield are undamaged.

PREFERRED

FLEXIBLE COAXIAL CABLE

The insulation jacket and shield(s) have been neatly trimmed, with minimal edge flash and no mechanical damage to the conductors, shielding, dielectric or insulation jacket. The center conductor stranding exhibits a normal twist pattern (lay).

PREFERRED
KAPTON® INSULATED CONDUCTORS

Kapton®-insulated conductors must be trimmed neatly and squarely, with minimal edge flash and no mechanical damage to the conductor or insulation.

PREFERRED

MECHANICAL STRIPPING PROCESS

The insulation jacket has been neatly trimmed, with minimal edge flash and no mechanical damage to the conductor or insulation. Conductor stranding lay (twist pattern) is undisturbed.

PREFERRED

MULTI-CONDUCTOR CABLE

The outer jacket, shield, strength members and conductor insulation have been neatly trimmed and removed, with minimal edge flash and no mechanical damage. Conductor stranding lay (twist pattern) is undisturbed.

PREFERRED

RIBBON CABLE

The outer jacket, conductive shield (if supplied), and conductor insulation have been neatly trimmed and removed, with minimal edge flash and no mechancial damage. The conductors are in normal planar orientation,and the drain conductor and/or shield are undamaged.

PREFERRED

SOLID CONDUCTOR

The insulation jacket has been neatly trimmed, with minimal edge flash and no mechanical damage to the conductor or insulation. Chemical/thermal/laser-trimmed conductors may exhibit slight discoloration of the insulation jacket(s) at the trimmed edge.

PREFERRED

STRANDED CONDUCTOR

The insulation jacket has been neatly trimmed, with minimal edge flash and no mechanical damage to the conductor or insulation. Conductor stranding lay (twist pattern) is undisturbed.

PREFERRED

THERMAL/ EXCIMER LASER STRIPPING

The insulation jacket has been neatly trimmed, with minimal edge flash and no damage to the conductor or insulation. Slight discoloration of the insulation jacket(s) at the trimmed edge.

ACCEPTABLE

BRAIDED SHIELD

The shield has been properly stripped, evenly trimmed, and exhibits a fairly uniform coverage pattern (braid weave). No severed strands.

NASA-STD-8739.4 [ 10.2 ] [19.6.1.a]

UNACCEPTABLE

SEVERED SHIELD STRANDS

Severed shield braid strands shall be cause for rejection.

NASA-STD-8739.4 [ 10.2 ] [ 19.6.2.a.4 ]

ACCEPTABLE

DIELECTRIC

The dielectric has been properly exposed, exhibiting a smooth, clean cut with minimal edge flash. Minor edge discoloration (due to thermal stripping) and/or surface scuffing is acceptable.

NASA-STD-8739.3 [ 7.2.2 ]
NASA-STD-8739.4 [ 10.1.2 ]

UNACCEPTABLE

DIELECTRIC DAMAGE

Coaxial cables with center conductors exhibiting damage to the dielectric (i.e.: burns, charring, cracks, crushing, cuts, deformation, necking, nicks, ringing, etc.) shall be rejected.

>NASA-STD-8739.3 [ 13.6.2.a.1 ]
NASA-STD-8739.4 [ 10.1.2 ], [19.6.2.a.1]

ACCEPTABLE

DISCOLORED INSULATION

Slight discoloration of the insulation jacket(s) at the trimmed edge is acceptable. Evidence of burning or charring is not acceptable.

NASA-STD-8739.3 [ 7.2.2 ]
NASA-STD-8739.4 [ 10.1.2 ], [19.6.1.a.1]

UNACCEPTABLE

BURNED/CHARRED/MELTED INSULATION

Burned, charred, or melted insulation is an indicator of improper process controls and/or stripping procedures, resulting in embrittlement, reduced dielectric properties and reduced reliability.

NASA-STD-8739.3 [ 13.6.2.a.1 ]
NASA-STD-8739.4 [19.6.2.a.2]

ACCEPTABLE

EDGE FLASH

Edge flash shall not exceed one-quarter insulated wire diameter (1/4 d). Edge flash is considered a contaminant, which may interfere with crimped or soldered terminations.

NASA-STD-8739.4 [ 10.1.6 ]

UNACCEPTABLE

EDGE FLASH/SMEARING

The edge flash is in excess of one-quarter insulated wire diameter (1/4 d), and the stripped section exhibits smearing (melted insulation/film) which is considered a contaminant.

NASA-STD-8739.4 [ 10.1.6 ]

ACCEPTABLE

ID RIBBON/STRENGTH MEMBER

The identification ribbon and/or strength member should be trimmed back to the insulation to prevent its inclusion into a soldered or crimped termination.

Best Workmanship Practice

UNACCEPTABLE

UNTRIMMED ID RIBBON/STRENGTH MEMBER

The identification ribbon and/or strength member has not been trimmed properly, which can interfere with the proper assembly of the soldered or crimped termination.

Best Workmanship Practice

ACCEPTABLE

NICKED SHIELD STRANDS

Nicked shield strands shall not exceed 10% of the total number of strands.

NASA-STD-8739.4 [ 10.2 ] [19.6.1.3]

UNACCEPTABLE

NICKED SHIELD STRANDS

The number of nicked shield strands is in excess of 10% of the total number of strands.

NASA-STD-8739.4 [10.2], [ 19.6.2.b.2 ]

ACCEPTABLE

PLANAR ORIENTATION
FLAT/RIBBON CABLE

The individual exposed conductors should be in parallel (planar) orientation to each other, following stripping.

Best Workmanship Practice

UNACCEPTABLE

NON-PLANAR ORIENTATION
FLAT/RIBBON CABLE

Non-planar oriented conductors are typically the result of poor handling. The conductors may be returned to their original orientation, provided no other damage is present.

Best Workmanship Practice

ACCEPTABLE

RETWISTED LAY

If the twist pattern (lay) of wire strands is disturbed, it shall be restored as nearly as possible to the original pattern. Retwisted lay is acceptable, provided no other damage is evident.

NASA-STD-8739.3 [7.2.4]
NASA-STD-8739.4 [10.1.4], [19.6.1.a.2]

UNACCEPTABLE

OVERTWISTED STRANDS

Strands twisted in excess of the normal twist pattern (lay) exert increased stress on individual strands, and may result in conductor breakage.

NASA-STD-8739.3 [7.2.4]
NASA-STD-8739.4 [10.1.4]

ACCEPTABLE

SCUFFED INSULATION/JACKET

Slight scuffing (a dull or rubbed appearance) of the insulation surface finish is acceptable, provided no other damage is evident.

NASA-STD-8739.3 [7.2.2]
NASA-STD-8739.4 [10.1.2]

UNACCEPTABLE

DAMAGED INSULATION/JACKET

The conductor insulation and /or cable jacket shall not exhibit any damage, such as nicks, cuts, or charring. Conductors/Jackets exhibiting damage (other than minor scuffing) shall not be used.

NASA-STD-8739.3 [13.6.2.a.1]
NASA-STD-8739.4 [19.6.2.a.2]

ACCEPTABLE

SMOOTH TOOL IMPRESSION MARKS

Smooth tool impression marks (slight cuts, nicks, scratches or scrapes) on the conductor surface, which do not expose base metal or reduce cross-sectional area, are acceptable.

NASA-STD-8739.3 [7.2.3]
NASA-STD-8739.4 [10.1.3]

UNACCEPTABLE

CONDUCTOR DAMAGE

Cuts, nicks, scratches or scrapes which reduce the conductor's overall cross-sectional area, reduce the current carrying capability and/or expose conductor base metal are rejectable.

NASA-STD-8739.3 [7.2.3], [13.6.2.a.8]
NASA-STD-8739.4 [10.1.3], [19.6.2.a.2]

ACCEPTABLE

STRANDING LAY/TWIST PATTERN

Conductor stranding exhibits a normal twist pattern (lay).

NASA-STD-8739.3 [7.2]
NASA-STD-8739.4 [10.1], [19.6.1.a]

UNACCEPTABLE

DISTURBED LAY

Standard conductors exhibiting a disturbed twist pattern (lay) shall be rejected. Stranding which has been returned to the original lay is acceptable, provided no other damage is present.

NASA-STD-8739.3 [7.2.4]
NASA-STD-8739.4 [10.1.4], [19.6.1.a.2]

UNACCEPTABLE

BIRDCAGED STRANDS

Birdcaged strands are typically the result of poor handling. The strands may be returned to the original twist pattern (lay), provided no other damage is present.

NASA-STD-8739.3 [7.2.4], [13.6.2.a.4]

UNACCEPTABLE

BURNED/CORRODED CONDUCTOR
(CHEMICAL STRIPPING)

Burns and/or corrosion are typically caused by the use of an extremely aggressive or chemically incompatible stripping agent, or excessive exposure.

NASA-STD-8739.3 [6.6.2.c], [13.6.2.a.7]
NASA-STD-8739.4 [19.6.2.a.2]

UNACCEPTABLE

BURNED/ETCHED STRANDS
(THERMAL STRIPPING)

Burned or etched strands are typically caused by current flow between the thermal stripper blades, or as a result of stripping an energized conductor.

NASA-STD-8739.3 [6.6.2.b], [13.6.3.a.7]
NASA-STD-8739.4 [19.6.2.a.2]

UNACCEPTABLE

CHEMICAL STRIPPING PROCESS
INCORRECT CONDUCTOR TYPES

Chemical stripping of other than solid, single-conductor wire (i.e.: coaxial cable, flat cable, multi-conductor cable, ribbon cable, shielded, stranded, etc.) is prohibited.

UNACCEPTABLE

CRUSHED STRANDS

Crushed strands are an indicator of improper tooling, resulting in reduced conductor cross-sectional area, reduced current carrying capability and reduced reliability.

NASA-STD-8739.3 [7.2.3]
NASA-STD-8739.4 [10.1.3], [19.6.2.a.2]

UNACCEPTABLE

CUT OR FRAYED STRANDS

Cut or frayed strands are an indicator of an improper process or tooling, resulting in reduced current carrying capability and reduced reliability.

NASA-STD-8739.3 [7.2.3], [13.6.2.a.8]
NASA-STD-8739.4 [10.1.3], [19.6.2.a.3]

UNACCEPTABLE

DAMAGED SHIELD

Cut, crushed, gouged, damaged or nicked shielding may result in reduced electrical isolation and/or short circuits.

Best Workmanship Practice

UNACCEPTABLE

OVERLAPPING STRANDS

Strands, retwisted and overlapping each other, will result in increased stress and difficulty in insertion, or the forming of a mechanical wrap.

NASA-STD-8739.3 [7.2.4]
NASA-STD-8739.4 [10.1.4]

UNACCEPTABLE

RINGED CONDUCTORS/STRANDS

Ringing is a symptom of an improper process or tooling. Ringing which reduces the overall cross-sectional area and/or results in exposed base metal shall be cause for rejection.

NASA-STD-8739.3 [6.6.1], [7.2.3], [13.6.2.a.8]
NASA-STD-8739.4 [6.6.1], [10.1.3], [19.6.2.a.2]

UNACCEPTABLE

UNEVENLY TRIMMED INSULATION

Unevenly trimmed insulation may result in reduced electrical isolation and/or short circuits, and may interfere with terminations.

Best Workmanship Practice

UNACCEPTABLE

UNEVENLY TRIMMED SHIELD

Unevenly trimmed shielding indicates poor technique and may result in improper electrical termination during connector assembly.

Best Workmanship Practice

UNACCEPTABLE

WICKING

Wicking of chemical stripping and/or cleaning agents under the insulation jacket is a long-term reliability concern.

NASA-STD-8739.3 [13.6.2.a.9]