IPC 7711A - 第38页

T able 1 Conformal Coating Characteristics Characteristics Conformal Coating T ype Epoxy Acrylic Poly- urethane Silicone Resin Para- xylylene Hard UUU Medium Hard UU Soft UU Heat Reaction UUU Surface Bond - Very Strong U…

Figure 1 Conformal Coating Identiﬁcation

CONFORMAL COATING IDENTIFICATION

START

DOES THE

COATING FEEL

SOFT/RUBBERY/

SPONGY

DOES THE

COATING HAVE A

NOTICEABLE

REACTION

TO HEAT

DOES THE

COATING HAVE A

NOTICEABLE

REACTION

TO HEAT

IS THE COATING

THICK AND HAVE A

DULL SURFACE

POLYURETHANE

RTV

ENCAPSULATION

SILICON

RESIN

DOES THE

REACTION FORM A

WHITE POWDER

IDENTIFICATION

COMPLETE

USE TABLE 1 FOR

CONFIRMATION

IS THERE A

REACTION TO

ALCOHOL

ACRYLIC

LACQUER

EPOXY

PARAXYLYLENE

YES

IPC-7711A/7721A

Number: 2.3.1

Revision:

Date: 2/98

Subject: Coating Removal, Identiﬁcation of Conformal Coating

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Table 1 Conformal Coating Characteristics

Characteristics

Conformal Coating Type

Epoxy Acrylic

Poly-

urethane

Silicone

Resin

Para-

xylylene

Hard UUU

Medium Hard UU

Soft UU

Heat Reaction UUU

Surface Bond - Very Strong UUU

Surface Bond - Strong UU

Surface Bond - Medium UU

Surface Bond - Light U

Solvent Reaction U

Non-porous Surface UUU U

Glossy Surface UUU

Semi-glossy Surface UU

Dull Surface U

Rubbery Surface U

Brittle UU

Chips UU

Peels and Flakes UU U

Stretches UU

Scratch, Dent, Bend, Tear UUU

Table 2 Conformal Coating Removal Methods

Conformal Coating

Removal Method

2.3.2

Solvent Method

2.3.3

Peeling Method

2.3.4

Thermal

Method

2.3.5

Grinding

Scraping

Method

2.3.6

Micro Blasting

Method

Paraxylyene 1 2 3

Epoxy 123

Acrylic 1 2 3 4

Polyurethane 3 1 2 4

Silicone Thin 1 2 3 4

Silicone Thick 1 2

NOTE: The preferred order for applying removal methods to speciﬁc coatings is numerically indicated. These removal methods are listed in ascending order.

More than one method may be required.

IPC-7711A/7721A

Number: 2.3.1

Revision:

Date: 2/98

Subject: Coating Removal, Identiﬁcation of Conformal Coating

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 procedure uses a solvent to remove surface coatings. This procedure can be

use for spot or overall coating removal of conformal coatings or solder resists.

Approved solvents may be used to remove specific soluble type coatings on a spot

basis by brushing or swabbing the local area with the controlled application of sol-

vent until the area is free of the coating material.

If warranted, all the soluble type coating can be removed by immersing and brush-

ing the entire printed board or printed board assembly.

To determine the appropriate coating removal procedure the coating must first be

identified. Refer to procedure number 2.3.1.

NOTE

Coating removal may require the use of one or more methods.

CAUTION

Determine, on a module by module basis, the hazards to parts, etc., by short term

immersion in the removal solvents. If chloride based or other harsh solvents are

used, extreme care must be exercised to prevent damage to base material, compo-

nent parts, plated-through holes, and solder joints. Some solvent coating removal

methods can cause expansion or swelling of the base material which can degrade

the printed board or printed board assembly. Under no circumstances should these

solvents be used except in a closely controlled process. It is recommended that the

printed board or printed board assembly be inspected to ensure that no damage has

occurred.

Before using any solvent refer to Material Safety Data Sheets.

REFERENCES

2.1 Handling Electronic Assemblies

2.2 Cleaning

2.3.1 Coating Removal, Identification of Conformal Coatings

2.4.1 Coating Replacement, Solder Resist

2.4.2 Coating Replacement, Conformal Coatings/Encapsulants

TOOLS AND MATERIALS

Brush

Cotton Swab

Polyimide Tape

Knife

Suitable Solvent

Thermal Parting Tool

Wood Stick

Figure 1 Apply tape to outline for

coating removal.

Figure 2 Apply solvent with foam

swab to remove coating.

7711A/7721A

General

Information and

Common Procedures

Revision:

Date: 2/98

Coating Removal,

Solvent Method

Number: 2.3.2

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.

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Provided by IHS under license with IPC

Not for Resale

No reproduction or networking permitted without license from IHS

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