IPC-TM-650 EN 2022 试验方法.pdf - 第169页

1 Scope This test method provides procedures to deter- mine the porosity of gold plating on both copper and nickel surfaces by chemical means. This method may also be used to test rhodium or palladium. 2 Applicable Docum…

Scope

This

test method is used to determine the pres-

ence and effectiveness of the protective coating deposited

over the PWB to prevent oxidation and facilitate good wetting

during soldering operations. The coating is removed during

soldering.

Applicable Documents

None

Test Specimens

3.1

Any

pre-production or production copper clad board at

least 5 cm x 5 cm. The specimen must either contain circuitry

or be completely copper clad. An uncoated bare copper clad

specimen must also be available for control purposes.

Equipment/Apparatus

4.1

Reagent

or commercial grade ferric chloride (42BE’)

etchant

4.2

Petrie

dishes or glass trays

4.3

Stop

watch

4.4

Lint-free

cloth

5 Procedure

5.1 Test

5.1.1

Place

one drop of ferric chloride on several locations

on the test specimens and the bare copper control speci-

mens.

5.1.2

Allow

to stand 10 seconds, then rinse with tap water

and wipe dry.

5.2

Evaluation

5.2.1

Examine

specimens and compare with bare control

specimen. Test specimens must show no copper etching,

proving the presence and effectiveness of protective coating.

Note

Slight

‘‘mottling’’ or a slight attack on the coated

surface indicates uneven deposition or insufficient solids of the

coating.

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.3.22

Subject

Copper

Protective Coating Quality

Date

2/78

Revision

Originating Task Group

N/A

Material

in this Test Methods Manual was voluntarily established by Technical Committees of the 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 the IPC.

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Scope

This

test method provides procedures to deter-

mine the porosity of gold plating on both copper and nickel

surfaces by chemical means. This method may also be used

to test rhodium or palladium.

Applicable Documents

None

Test Specimens

3.1

Any

test, pre-production, or production sample of gold-

plated circuitry

Apparatus

4.1

Whatman

No. 542 filter paper

4.2 Glass

lab trays

4.3

Powdered

Alumina (or Magnesia)

4.4

Distilled

water, 4 liters

4.5

Aluminum

panels, 15 cm x 15 cm (high purity)

4.6

volt DC power supply

4.7

Photographic

blotting paper

4.8

One

pint of 10% solution cadmium chloride

4.9 One

pint of hydrochloric acid (1.16 to 1.8 specific grav-

ity)

4.10

One

pint of 5% solution sodium sulfide

4.11

Lab

press (or clamps)

4.12

0.8%

solution Nioxime (cyclohexane 1:2 dione dioxime)

Procedure

5.1 Preparation

5.1.1

The

high-purity aluminum panels must at all times be

free from grease and foreign matter likely to cause inoperative

areas on the cadmium sulfide paper.

5.1.2 In

order to preserve the active life of the cadmium sul-

fide papers, they should be stored in a dark, sealed container.

The shelf life of the papers is approximately four to six weeks.

5.1.3

After

this test, the contacts must be cleaned again as

before, rinsed in hot distilled water, and carefully dried. The

used cadmium sulfide paper must not be stored in contact

with the plated surface of the board.

5.2

Gold on Copper Test Method

5.2.1

Soak

the Whatman 542 filter paper for 10 minutes in a

fresh 10% solution of cadmium chloride in distilled water con-

taining 0.1% by volume of hydrochloric acid.

5.2.2

Remove

the excess solution by blotting.

5.2.3 Allow

the paper to dry partially, then immerse in a

fresh 5% solution of sodium sulfide in distilled water for 30

seconds, after which time the paper must be of a uniform yel-

low color (indicating a complete precipitate of cadmium sul-

fide).

5.2.4

Soak

the photographic blotting paper in distilled water

and dry to a degree of dryness that produces consistent,

sharply defined electrograms.

5.2.5

Lightly

clean the gold plating with powdered alumina

(or magnesia) and water to remove any extraneous surface

contamination, then flush with distilled water and dry. The

cleaned surfaces must be kept clean until the test is com-

pleted.

5.2.6

Place

a piece of the cadmium sulfide paper on the

plated sample (which acts as the anode) followed by a piece

of the photographic blotting paper, the latter being in contact

with a freshly cleaned high-purity aluminum panel (which acts

as the cathode).

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.3.24

Subject

Porosity

of Gold Plating

Date

2/78

Revision

Originating Task Group

N/A

Material

in this Test Methods Manual was voluntarily established by Technical Committees of the 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 the IPC.

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5.2.7

Compress

the assembly so that the pressure between

the cadmium sulfide paper and the sample is uniform and

between 14 kg/cm2 and 18 kg/cm2.

5.2.8

While

the assembly is under compression, pass a

smooth, ripple free DC source not exceeding 12 volts

between the cathode and anode.

5.2.9 Set

the current initially at 8 mA/cm

anode area and

energize for 30 seconds.

5.2.10

Allow

the electrograms produced on the cadmium

sulfide paper to dry.

5.2.11

corresponding brown stain on the paper reveals

the presence of any defect in the plated coating.

5.2.12

Visually

examine the specimen at 10X magnification.

5.3

Gold on Nickel Method

5.3.1

Soak

the Whatman 542 filter paper for 10 minutes in a

0.8% solution of nioxime (cyclohexane 1:2 dione dioxime) and

distilled water.

5.3.2

Remove

the excess solution with blotting paper. The

paper must be hung up to dry.

5.3.3

Repeat

the steps in 5.2, except moisten the piece of

nioxime paper with distilled water and expose the ammonia

vapor.

5.3.4

Remove

the excess by blotting. The ‘‘backing pad’’ of

photographic blotting paper is to be used dry.

5.3.5 Expose

the electrograms produced on the nioxime

paper to ammonia vapor, then allow to dry.

5.3.6

corresponding purple-red stain on the paper reveals

the presence of any defects in the gold plating.

5.3.7

Visually

examine the specimens at 10X magnification.

IPC-TM-650

Number

2.3.24

Subject

Porosity

of Gold Plating

Date

2/78

Revision

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