IPC 7711A - 第204页

NOTE Do not use magnet or coil wire, due to its insulative enamel coating, to prevent dam- age to wire during the wrapping procedure. Use only a single layer of wrapping on the overlapped wires and fold the end of the wi…

EQUIPMENT REQUIRED

Soldering system

Soldering handpiece

Chisel tip

MATERIALS

Flux

Flux-cored solder

Insulative tubing

PROCEDURE

1. Install tip

2. Start with tip temperature of approximately 260°C and change as necessary.

3. Strip the wires. Each wire end should have the same length of insulation removed

so that they appear identical. Each wire end should be stripped a minimum of four

(four) wire diameters (a wire diameter is the outside diameter of the insulator

which covers the conductor). Pre-tin wires in accordance with guidelines in para-

graph 7 in 8.1. (See Figure 1.)

4. Place shrink-sleeving/tubing/wire designators, etc. onto the wire to be spliced

and slide down the wire far enough to avoid interference during soldering. The

inside diameter of the shrink-sleeving should be selected to ensure that a snug,

firm, weather-tight seal will exist after shrinking.

NOTE

Step three (below) requires a single strand of wire, approximately 7.5 cm long, to be

available for wrapping the overlapped wire ends. It is easiest to strip 7.5 cm of wire

by making 3 separate strips (each approximately 2.5 cm long from the spool/reel of

repair wire).

5. If possible, position wires on a flat surface so that the tinned lengths of wire over-

lap and are against each other (like the first two fingers on your hand) and the end

of wire ‘‘a’’ butts against the ends of the insulation of wire ‘‘b.’’ (See Figure 2.) If

identical lengths of insulation were removed, then the end of wire ‘‘b’’ will butt

against the insulation of wire ‘‘a.’’ If it is not possible to position the wires on a flat

surface, then position the wires as described above and secure in position using

hemostats, alligator clips, etc. As a last ditch expedient, the wires can be tack

soldered into the described position. If tack soldered, do not add solder, just heat

the wires sufficiently to achieve a solder bond between the tinned wires.

6. Using a single strand of wire (approximately #30 awg) from a stranded wire (see

Note above), wrap the overlapped wires to achieve sufficient mechanical security

to prevent movement of the overlapped ends during soldering. (See Figure 3.)

Figure 1 Strip and Tin Wires

Figure 2 Line Up Wires

Figure 3 Wrap with #30 Awg Wire

Figure 4 Solder Connection

Figure 5 Cover with Heat-Shrinkable

Tubing

7711A

Rework of

Electronic Assemblies

Revision:

Date: 2/98

Lap Splices

Number: 8.1.4

Product Class: N/A

Skill Level: Intermediate

Level of Conformance: Low

Material in this manual, IPC-7711 Rework of Electronic Assemblies, 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.

Page1of2

Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

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

NOTE

Do not use magnet or coil wire, due to its insulative enamel coating, to prevent dam-

age to wire during the wrapping procedure.

Use only a single layer of wrapping on the overlapped wires and fold the end of the

wire used for wrapping back down against the wrap surface.

7. Select a soldering iron tip appropriate to soldering the overlap splice. Establish a

heat bridge in the center of the overlapped wires and add sufficient solder to

achieve a complete solder fillet between the full length of the overlapped wires.

The completed solder connection may have a slightly convex fillet for the length

of the connection, as long as the individual wire wraps used to secure the spliced

wires are clearly visible in the solder. (See Figure 4.)

8. Clean the completed connection with the appropriate solvent and visually inspect

in accordance with stated requirements.

9. Position insulative sleeving, shrink-sleeving, or protective tubing over the splice,

assuring that the splice is centered in the length of the sleeving/tubing. Apply heat

to shrink-sleeving as necessary to achieve a tight fit over the splice. Position pro-

tective tubing (if used) over shrink-sleeving and mechanically secure as appropri-

ate. (See Figure 5.)

IPC-7711A

Number: 8.1.4

Revision:

Date: 2/98

Subject: Lap Splice

Page2of2

Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

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

OUTLINE

This method can be used to add, change or replace legend and markings on printed

boards or printed board assemblies. This method uses epoxy ink and an ink stamp

to place the legends on the printed board surface in much the same manner as tak-

ing a ‘‘finger print.’’

REFERENCES

2.1 Handling Electronic Assemblies

2.2 Cleaning

2.5 Baking and Preheating

2.6 Epoxy Mixing and Handling

TOOLS & MATERIALS

Cleaner

Cleaning Wipes

Epoxy Ink

Ink Plate

Ink Roller

Knife

Microscope

Oven

Peg Stamps

PROCEDURE

1. Clean the area.

2. Scrape off any remaining character or legend with a knife and clean the area.

CAUTION

Abrasion operations can generate electrostatic charges.

3. Select the appropriate characters from the peg stamp set or have a special stamp

made up.

4. Mix the epoxy ink. White is the most common color. Spread a thin even coating

of the epoxy ink on the ink plate or on a smooth surface.

5. Gently press the peg stamp into the epoxy coating to coat the character surface.

6. Gently press the peg stamp onto the desired location on the printed wiring board

surface. (See Figure 1.)

7. Cure the epoxy ink per the manufacturer’s instructions.

EVALUATION

1. Visual examination for proper characters, positioning and legibility.

Figure 1 Apply legend using a peg

stamp.

Figure 2 Completed legend repair.

7721A

Repair and

Modification of

Printed Boards and

Electronic Assemblies

Revision:

Date: 2/98

Legend/Marking,

Stamping Method

Number: 2.7.1

Product Class: R, F, W, C

Skill Level: Intermediate

Level of Conformance: High

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.

Page1of2

Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

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