IPC 7711A.pdf - 第313页

3. Remove solder from the connection point if needed. Clean the area. 4. Measure approximately the length of each wire needed. JUMPER WIRE SELECTION 1. Bare conductor jumper wires longer than 12.7 mm [0.50 in] shall not …

GENERAL RULES

1. Jumper wires should be placed on the component side of the assembly or

printed board unless otherwise specified.

2. Jumper wires shall be routed in an XY manner as directly as feasible, making as

few bends as possible. (See Figure 1.)

3. Jumper wires shall not be raised more than 3.2 mm [0.125 in] above the board

surface or not above components or leads in such a way that they will interfere

with PC board mounting.

4. Bare conductor jumper wires longer than 12.7 mm [0.50 in] shall not be used.

Bare conductor jumper wires shorter than 12.7 mm [0.50 in] shall not violate the

minimum electrical clearance.

NOTE

The 12.7 mm [0.50 in] dimension refers to the length between terminations.

5. Jumper wires may pass over lands provided sufficient slack is available so that

the wire can be moved away from the land for component replacement. Jumper

wires shall not pass over pads or vias used as test points.

6. Jumper wires shall not be routed under or over component leads or component

bodies. Contact with heat sinks must be avoided.

7. Jumper wires shall not pass through component foot prints unless the layout of

the assembly prohibits the routing in other areas.

8. Jumper wires shall have stress relief.

9. Jumper wires may be routed through plated through holes provided the wire is

insulated and insulation sleeving is placed in the hole. If a hole is needed, use

the following method. (See Figure 2.)

A. Drill a hole 0.25 mm [0.010 in] larger than the insulation diameter.

B. Inspect the hole for burs or exposed internal circuits.

C. Document the added hole on a control drawing.

NOTE

Be careful that the drilled hole does not interfere with surface and internal con-

ductors.

10. Jumper wires soldered into plated through holes must be discernible on the

opposite side.

11. Jumper wires soldered to lifted or clipped component leads may require insula-

tion to prevent shorting. (See Figure 3.)

12. Jumper wires may be terminated by a variety of methods. See illustrations.

PC BOARD PREPARATION

1. Clean the area.

NOTE

When wires are in place cleaning will often be more difficult.

2. Remove coating material or oxidization as necessary from the component leads,

pads, or conductors where wire terminations will be soldered. Clean the area.

Figure 5 Bond wires using adhesive.

Figure 6 Adhesive coated wires are

heat bonded.

IPC-7721A

Number: 6.1

Revision:

Date: 11/99

Subject: Jumper Wires

Page2of10

Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

--``,``,-`-`,,`,,`,`,,`---

3. Remove solder from the connection point if needed. Clean the area.

4. Measure approximately the length of each wire needed.

JUMPER WIRE SELECTION

1. Bare conductor jumper wires longer than 12.7 mm [0.50 in] shall not be used.

Bare conductor jumper wires shorter than 12.7 mm [0.50 in] shall not violate the

minimum electrical clearance.

NOTE

The 12.7 mm [0.50 in] dimension refers to the length between terminations.

2. Silver plated wire must not be used; under some conditions corrosion of the wire

can occur.

3. The smallest diameter wire that will carry the required current should be selected.

4. Insulation requirements of the wire should withstand soldering temperatures, have

some resistance to abrasion, have a dielectric resistance equal to or better than

the board insulation material.

5. Recommended wire is solid insulated copper wire, tin lead plated, 22 to 32 AWG

with Kynar, Milene, Kapton, Teflon or equivalent insulation.

CAUTION

Wires with nicked or damaged conductors should not be used.

JUMPER WIRE PREPARATION

1. Cut the jumper wires approximately 12.7 mm [0.50 in] longer than the estimated

length needed.

NOTE

The length and gauge of the jumper wire may be critical. All wires have an elec-

trical resistance (impedance) to the flow of electricity. This impedance is important

to electronic circuitry. Always refer to wiring lists for specific jumper wire require-

ments.

2. Strip insulation from each end of the jumper wire.

NOTE

Strip length is dependent on the termination style.

3. If required, tin the stripped ends with solder. Clean if necessary.

JUMPER WIRE TERMINATING AND ROUTING

1. Form the wire as needed and place the wire in position depending on the termi-

nation style. Center the wire on the component lead or pad, do not overhang

sides. If the wire is soldered to a pin, terminal or component lead, wrap the wire

a minimum of 90°.

2. Solder one end of the wire. Clean if necessary.

NOTE

Solder joint length must meet acceptability requirements.

IPC-7721A

Number: 6.1

Revision:

Date: 11/99

Subject: Jumper Wires

Page3of10

Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

--``,``,-`-`,,`,,`,`,,`---

CAUTION

The insulation shall not be stripped back more than two wire diameters from the

solder joint. Wire insulation may touch but not penetrate the solder joint provided

proper wetting of the wire is evident.

3. Bend the wire as needed and run the wire along board surface. Route the jumper

wire using the shortest route in an XY direction with the fewest possible bends to

the second termination point.

NOTE

Jumper wires shall not be routed under or over component leads or component

bodies. Contact with heat sinks must be avoided.

CAUTION

Do not bend the wire tighter than a radius of three times the conductor diameter.

4. After routing the jumper wire, solder the opposite end. Clean if necessary.

CAUTION

Wires soldered to lifted or clipped components leads may require insulation to

prevent shorting.

JUMPER WIRE BONDING

1. After the wire has been soldered at both ends and cleaned if necessary, the wire

should be bonded to the board surface.

NOTE

Bonding is not required if wire is insulated and insulated length is less than 25 mm

[1.00 in].

2. Bond the jumper wire using one of the following methods.

A. Tape Dots or Tape Strips. (See Figure 4.)

B. Quick Set Adhesive. (See Figure 5.)

C. Hot Melt Adhesive. (See Figure 5.)

D. Hot Bonding. Some jumper wires are manufactured with a special thermo-set

adhesive coating and are thermally bonded to the board surface with a spe-

cial bonding tool. (See Figure 6.)

3. Bond the jumper wire within 6.0 mm [0.25 in] of each solder joint.

4. Bond the jumper wire within 6.0 mm [0.25 in] of each bend in the wire.

5. Bond the jumper wire at intervals not less than 25 mm [1.00 in] on straight runs.

IPC-7721A

Number: 6.1

Revision:

Date: 11/99

Subject: Jumper Wires

Page4of10

Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

--``,``,-`-`,,`,,`,`,,`---