DISCRETE WIRING
JUMPER WIRES
jumper wires
JUMPER WIRES

Jumper wires (a.k.a.: haywires) are used to facilitate minor circuit modifications to printed wiring assemblies (PWA), rather than redesign and manufacture a new board. While their use is an accepted practice, the customer must grant approval prior to their use and installation.
Jumper wires are usually solid, insulated copper conductor with tin/lead plating (i.e.: wire wrap wire), although jumpers less than 25mm (0.984 in.) may be uninsulated, provided the jumper is not liable to short between lands or component leads. Silver-plated and/or stranded wire shall not be used.

component termination side solder termination side

PREFERRED

COMPONENT TERMINATION SIDE

Wire route is the shortest path. Wire does not pass over or under components, or pass over any land or via used as a test point. Sufficient slack to allow relocation during component replacement.

Best Workmanship Practice

PREFERRED

SOLDER TERMINATION SIDE

Wire route is the shortest path. Wire does not cross component footprints or lands, except where unavoidable. Wire does not pass over any land or via used as a test point.

Best Workmanship Practice

jumper wire staked at intervals solid insulated conductor

MANDATORY

STAKING

Jumper wire is staked at intervals specified by engineering documentation. The wire is staked at all changes of direction to restrict movement and as close to the solder termination as possible.

NASA-STD-8739.1 [ 9.2.4 ]

MANDATORY

SOLID, INSULATED CONDUCTOR

Jumper wires shall be solid, insulated copper conductor with tin/lead plating (i.e.: wire wrap wire). Stranded, silver-plated wire shall not be used.

Best Workmanship Practice

NASA WORKMANSHIP STANDARDS
NASA logo Released:
03.30.2001
Revision:
Revision Date:
Book:
3
Section:
3.02
Page:
1




DISCRETE WIRING
JUMPER WIRES (cont.)
component lead termination gull wing surface mount technology lap termination

ACCEPTABLE

COMPONENT LEAD TERMINATION

The termination shall be wrapped a minimum of 90º, exhibit proper insulation clearance, the outline shall be evident in the fillet, and shall not violate minimum electrical spacing.

Best Workmanship Practice

ACCEPTABLE

LAP TERMINATION, GULL WING SMT

The jumper wire termination shall be a minimum of 75% of the lead length, as measured between the toe and knee, and shall not entend past the top of the component body.

Best Workmanship Practice

J-leaded surface mount technology lap termination J-Leaded surface mount technology minimum lap termination

PREFERRED

LAP TERMINATION, J-LEAD SMT

The jumper wire termination length shall be equal to the lead height (L), and shall not extend past the top of the component body.

Best Workmanship Practice

ACCEPTABLE

LAP TERMINATION, J-LEAD SMT (MINIMUM)

The jumper wire termination length shall be a minimum of 75% of the lead heigth (L), and shall not extend past the top of the component body.

Best Workmanship Practice

plated through hole lap termination surface mount technology lap termination

ACCEPTABLE

LAP TERMINATION, PTH

The termination shall exhibit a lap solder joint a minimum of 75% of lead length, proper insulation spacing, a discernable outline and not violate minimum electrical spacing requirements.

Best Workmanship Practice

ACCEPTABLE

LAP TERMINATION, SMT

The jumper wire termination shall be parallel to the longest dimension of the pad, with the solder fillet equal to the land width (L).

Best Workmanship Practice

NASA WORKMANSHIP STANDARDS
NASA logo Released:
03.30.2001
Revision:
Revision Date:
Book:
3
Section:
3.02
Page:
2




DISCRETE WIRING
JUMPER WIRES (cont.)
surface mount technology minimum lap termination vacant land or pad lap termination

ACCEPTABLE

LAP TERMINATION, SMT (MINIMUM)

The jumper wire termination shall be parallel to the longest dimension of the pad, with the solder fillet > 50% of the land width (L).

Best Workmanship Practice

ACCEPTABLE

LAP TERMINATION - VACANT LAND/PAD

The jumper wire termination shall be parallel to the longest dimension of the pad (L), shall be a minimum of 50% of the dimension (L), and shall not overhang the pad.

Best Workmanship Practice

uninsulated wire jumper wire terminated and soldered into a via hole

ACCEPTABLE

UNINSULATED WIRE

Uninsulated jumper wires shall be less than 25mm (0.984 in.) long, and shall not violate minimum electrical spacing requirements. Silverplated, stranded wire shall not be used.

Best Workmanship Practice

ACCEPTABLE

VIA TERMINATION

Jumper wires may be terminated and soldered into a via hole.

Best Workmanship Practice

plated through hole improper lap termination improper lap termination

UNACCEPTABLE

IMPROPER LAP TERMINATION, PTH

The lap joint is less than the required 75% of the lead length.

Best Workmanship Practice

UNACCEPTABLE

IMPROPER LAP TERMINATION

The lap termination shall not overhang the land and/or violate minimum electrical spacing.

Best Workmanship Practice

NASA WORKMANSHIP STANDARDS
NASA logo Released:
03.30.2001
Revision:
Revision Date:
Book:
3
Section:
3.02
Page:
3




DISCRETE WIRING
JUMPER WIRES (cont.)
improper lap termination gull wing surface mount technology improper lead termination

UNACCEPTABLE

IMPROPER LAP TERMINATION
GULL WING SMT

The jumper wire termination shall be a minimum of 75% fo the lead length (L), as measured between the toe and knee.

Best Workmanship Practice

UNACCEPTABLE

IMPROPER LEAD TERMINATION

The termination wrap shall be a minimum of 90º and a maximum of 180º, with evidence of proper insulation gap and without overhanging the component termination.

Best Workmanship Practice

improper routing over test points improper routing over and under components

UNACCEPTABLE

IMPROPER ROUTING
(OVER TEST POINTS)

Jumper wires shall not be routed over circuit patterns or vias that are used as test points.

Best Workmanship Practice

UNACCEPTABLE

IMPROPER ROUTING
(OVER/UNDER COMPONENTS)

Jumper wires shall not be routed over or under components.

Best Workmanship Practice

improper staking jumper wire terminated and soldered into a plated through hole occupied by a component lead

UNACCEPTABLE

IMPROPER STAKING

The jumper wire is not staked as specified. The wire is loose and can extend above the height of adjacent components.

Best Workmanship Practice

UNACCEPTABLE

IMPROPER TERMINATION
(OCCUPIED PTH)

Jumper wires shall not be terminated and soldered into plated-through holes (PTH) occupied by a component lead.

Best Workmanship Practice

NASA WORKMANSHIP STANDARDS
NASA logo Released:
03.30.2001
Revision:
Revision Date:
Book:
3
Section:
3.02
Page:
4





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