IPC 7711A - 第312页

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 ben…

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OUTLINE
This procedure covers the repair/modification of printed boards and electronic
assemblies by the use of jumper wires to complete electrical continuity between two
points. This procedure is meant to provide a foundation for adding jumper wires dur-
ing the repair/modification process. The techniques and guidelines are based on
general commercial and industry practices.
Jumper wires fall into three (3) categories
1. Those that are considered wires and are installed during assembly. The routing,
termination, and bonding of these jumper wires are documented by engineering
instructions or drawing notations.
2. Those that are added after assembly to effect a change or modification. The
routing, termination, and bonding of these jumper wires are documented by engi-
neering change notice instructions or drawing notations.
3. Those that are added to correct a defect.
This procedure has nine main sections.
1. References
2. Tools and Materials
3. General Rules
4. PC Board Preparation
5. Jumper Wire Selection
6. Jumper Wire Preparation
7. Jumper Wire Termination and Routing
8. Jumper Wire Bonding
9. Jumper Wire Termination Figures
REFERENCES
1.0 Foreword
2.1 Handling Electronic Assemblies
2.2 Cleaning
2.5 Baking and Preheating
TOOLS & MATERIALS
Adhesive, Hot Melt
Adhesive, Quick Set
Cleaner
Cleaning Wipes
Flush Cutter
Flux, Liquid
Smooth Pliers
Solder
Soldering Iron with Tips
Tape Dots
Wire
Wire, Adhesive Coated
Wire Stripper
Figure 1 Route jumper wires.
Figure 2 Use sleeving through PTH.
Figure 3 Use insulated wire if
required.
Figure 4 Bond wires using tape dots
or strips.
7721A
Repair and
Modification of
Printed Boards and
Electronic Assemblies
Revision:
Date: 11/99
Jumper Wires
Number: 6.1
Product Class: R/F/W/C
Skill Level: Intermediate
Level of Conformance: N/A
Material in this manual was voluntarily established by Technical Committees of IPC. This material is advisory only and its use
or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of this material.
Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement. Equipment
referenced is for the convenience of the user and does not imply endorsement by IPC.
Page1of10
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---
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
Copyright Association Connecting Electronics Industries
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
Copyright Association Connecting Electronics Industries
Provided by IHS under license with IPC
Not for Resale
No reproduction or networking permitted without license from IHS
--``,``,-`-`,,`,,`,`,,`---