IPC 7711A - 第285页

OUTLINE This method is used to replate edge contacts by selective swab plating. Edge con- tacts may require replating if they become contaminated with solder or are scratched during handling. Other applications may arise…

NOTES

IPC-7721A

Number: 4.6.2

Revision:

Date: 2/98

Subject: Edge Contact Repair, Film Adhesive Method

Page4of4

Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

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OUTLINE

This method is used to replate edge contacts by selective swab plating. Edge con-

tacts may require replating if they become contaminated with solder or are scratched

during handling. Other applications may arise when the plating on the edge contacts

does not meet the minimum thickness specification or if the specification changes.

This electroplating process uses a DC power supply. One lead is connected to the

connector edge contacts that need plating. A second lead is connected to the plat-

ing probe. The plating probe has an anode fastened to the tip. The anode has

absorbent wrapping. The anode is dipped into high-speed proprietary plating solu-

tions. When the saturated anode is swabbed across the printed wiring board con-

nector edge contacts, the metal contained in the solution is plated wherever electri-

cal contact is made. Prior to replating any solder contamination must be removed.

CAUTION

This method can be used to replate any metal surface including connector edge

contacts, but it is essential that the surface to be plated is free of deep scratches,

nicks, pin holes or other defects. If the edge contacts need to be replaced see

appropriate procedure.

SAFETY

A thorough review of this method should be made before repairs are attempted.

Technicians should become familiar with the tools included and should practice on

scrap printed wiring boards

To expect the best results a clean work environment is essential. A smooth work

surface and good lighting are recommended. Safety glasses and safety gloves

should always be worn when handling hazardous chemicals.

The work area should be adequately ventilated. It is particularly important to have

adequate ventilation when using gold solution, since gold solution contains a very

small percentage of free cyanide. If ventilation is not adequate, use a fan to move

fumes away from the operator.

CAUTION

It is essential to follow the manufacturer’s instructions supplied with the plating

equipment.

REFERENCES

2.1 Handling Electronic Assemblies

2.2 Cleaning

Figure 1 Apply tape.

Figure 2 Flow solder.

Figure 3 Solder stripping solution.

Figure 4 Rinse.

7721A

Repair and

Modification of

Printed Boards and

Electronic Assemblies

Revision:

Date: 2/98

Edge Contact Repair,

Plating Method

Number: 4.6.3

Product Class: R, F, W, C

Skill Level: Advanced

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.

Page1of6

Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

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TOOLS & MATERIALS

Abrasive Pad

Board Support

Burnisher

Cleaner

Cleaner Wipes

Connector Edge

Plating System

Conductive Pen

Desoldering Braid or

Desoldering System

Eraser Stick

Gloves, Antistatic

Polyimide Tape

Knife

Liquid Flux

Peel Testing Tape

Pin Fixtures

Plating Anodes

Plating Cables

Plating Probe

Plating Solution, Gold

Plating Solution, Nickel

Plating Solution, Electroclean

Plating Solution, Solder Strip

Plating Tape

Power Supply

Probe Clip

Rinse Bottle

Rinse Tray

Safety Glasses

Solder

Solder Iron

Solution Cups

Solution Tray

Swab

Thickness Measuring System,

Gold and Nickel

Water/Air Sprayer

Wire, Buss, 30 AWG

Work Sink

PREPARATION − Remove Solder Contamination

CAUTION

Safety glasses and safety gloves should always be worn when handling hazardous

chemicals. Do not work within a small enclosed room without supplemental ventila-

tion. If ventilation is not adequate, use a fan to move fumes away from the operator.

1. Clean the rework area.

2. Apply plating tape to the printed wiring board surface surrounding the area to

be reworked. (See Figure 1.) The plating tape will protect adjacent components

and the printed wiring board surface from unwanted exposure to stripping and

plating solutions.

3. Flow solder over the entire area of any contacts that have contamination using

a soldering iron. This provides a more even surface when plating. Remove the

bulk of the solder contamination using desoldering tools or desoldering braid.

(See Figure 2.)

4. Clean the area.

5. Place the printed wiring board on the board support so that the leading edge

overhangs the rinse tray.

6. Swab the solder stripping solution over the solder contamination using a swab.

Swab the surface until all remaining solder has been stripped off. (See Figure 3.)

7. Thoroughly rinse the entire area with water. (See Figure 4.)

8. Mildly buff the contacts using abrasive pad. Mild buffing will prepare the surface

for plating and remove any remaining solder contamination.

9. Thoroughly rinse with water to remove any residue.

Figure 5 Solder a wire to the edge of

the contacts needing plating.

Figure 6 Apply conductive paint to

the edge of the contacts.

Figure 7 Sample plating anodes

shown with fabric wrapping.

Figure 8 Brush the surface with the

saturated plating probe.

IPC-7721A

Number: 4.6.3

Revision:

Date: 2/98

Subject: Edge Contact Repair, Plating Method

Page2of6

Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

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