IPC-TM-650 EN 2022 试验方法.pdf - 第726页

5.3.3 Immerse in 5% sulfuric acid (by volume) at 65 ± 5 °C [149 ± 9 °F] for one minute to remove the tarnish film. 5.3.4 Immerse in a solution of 25% m/v ammonium persul- phate (in 0.5% v/v sulfuric acid) at 23 ± 2 °C [7…

Scope

This

test method is designed to determine the

corrosive properties of flux residues under extreme environ-

mental conditions. A pellet of solder is melted in contact with

the test flux on a sheet metal test piece. The solder is then

exposed to prescribed conditions of humidity and the result-

ing corrosion, if any, is assessed visually.

Applicable Documents

IPC J-STD-004

Requirements

for Soldering Fluxes

IPC-TM-650

Test

Methods Manual

2.3.34 Solids Content, Flux for Fluxes for Soft Soldering

IEC

61189-5

Test

Methods for Electrical Materials, Intercon-

nection Structures and Assemblies - Part 5: Test Methods for

Printed Board Assemblies

Test Specimen

least 0.035 g of flux solids, 0.3 g sol-

der paste, 1 g wire, or 1 g preform with an equivalent amount

of solids. Flux solids are defined as the residue described in

IPC-TM-650, Test Method 2.3.34, Solids Content, Fluxes. All

solvent must have been evaporated from the specimen in a

chemical fume hood.

4 Apparatus and Reagents

4.1 Apparatus

4.1.1

Solder

pot.

4.1.2

Humidity

chamber capable of achieving 40 ± 3 °C

[104 ± 5.4 °F] and 93 ± 5% relative humidity.

4.1.3 Air

circulating drying oven.

4.1.4

Microscope

having 20X minimum.

4.1.5

Analytical

balance capable of weighing 0.001 g.

4.1.6

Three

50 mm x 50 mm x 0.5 mm [1.969 in x 1.969 in

x 0.00197 in] 99% pure copper sheets.

4.1.7

mm [0.748 in] steel ball (approximate).

4.1.8 Laboratory

press.

4.1.9

Tongs.

4.2

Reagents

All

chemicals must be reagent grade and

water must be deionized (2 megohm-cm minimum resistivity

recommended).

4,2,1

Ammonium

persulphate.

4.2.2

Sulfuric

acid, relative density 1.84.

4.2.3

Degreasing

agent: acetone, or petroleum ether.

Procedures

5.1 Chemicals

5.1.1

Ammonium

persulphate (25% m/v in 0.5% v/v sulfuric

acid). Dissolve 250 g of ammonium persulphate in water and

add cautiously 5 ml of 5% sulfuric acid (relative density 1.84).

Mix, cool, dilute to 1 liter and mix. This solution should be

freshly prepared.

5.1.2

Sulfuric

acid (5% v/v). To 400 ml of water cautiously

add 50 ml of sulfuric acid (relative density 1.84). Mix, cool,

dilute to 1 liter and mix.

5.2

Test Panel

5.2.1

Form

a 3.0 mm [0.018 in] (approximate) deep circular

depression in the center of the copper test panel by forcing a

19.0 mm [0.018 in] steel ball into a 25 (approximate) mm hole

to form a cup.

5.2.2 Bend

one corner of the test panel up to facilitate sub-

sequent handling with tongs.

5.3

Test Panel Pretreatment

5.3.1

Immediately

before performing test, pretreat as follows

using clean tongs for handling.

5.3.2

Degrease

with a suitable neutral organic solvent such

as acetone, or petroleum ether.

2215

Sanders Road

Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.6.15

Subject

Corrosion,

Flux

Date

06/04

Revision

Originating Task Group

Flux Specifications Task Group, (5-24a)

Material

in this Test Methods 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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5.3.3

Immerse

in 5% sulfuric acid (by volume) at 65 ± 5 °C

[149 ± 9 °F] for one minute to remove the tarnish film.

5.3.4

Immerse

in a solution of 25% m/v ammonium persul-

phate (in 0.5% v/v sulfuric acid) at 23 ± 2 °C [73.4 ± 3.6 °F]

for one minute to etch the surface uniformly.

5.3.5

Wash

in running tap water for five seconds. Immerse

in 5% sulfuric acid (by volume) at 23 ± 2°C [73.4 ± 3.6 °F] for

one minute.

5.3.6 Wash

for five seconds in running tap water, then rinse

thoroughly in deionized water.

5.3.7

Rinse

with acetone.

5.3.8

Allow

to dry in clean air.

Note: Use the test piece as soon as possible or store up to

one hour in a closed container.

5.4

Solder for Liquid or Paste Flux Test

5.4.1

Weigh

a 1.00 ± 0.05 gram specimen of solid solder.

5.4.2

Degrease

the solder specimen with a suitable neutral

organic solvent such as acetone, or petroleum ether.

5.4.3

Solder

may be in the form of pellets or tight spirals of

solid solder wire.

5.5

Test

5.5.1

Heat

solder pot so that solder bath stabilizes at 235 ±

5 °C [455 ± 9 °F].

5.5.2

Liquid or Paste Flux

5.5.2.1

Place

0.035 g of flux solids into the depression in

the test panel. Add the solid solder pellets or spirals.

5.5.2.2

Using

tongs, lower the test panel onto the surface of

the molten solder.

5.5.2.3

Allow

the test panel to remain in contact with the

bath until the solder specimen in the depression of the test

panel melts. Maintain this position for5±1seconds before

removing the test panel from the bath. Cool the test panel to

room temperature.

5.5.3

Cored Wire or Cored Preform

5.5.3.1

Place

1 gram of flux cored wire or perform into the

depression in the test panel.

5.5.3.2

Using

tongs, lower the test panel onto the surface of

the molten solder.

5.5.3.3

Allow

the test panel to remain in contact with the

bath until the solder specimen in the depression of the test

panel melts. Maintain this position for5±1seconds before

removing the test panel from the bath. Cool the test panel to

room temperature.

5.5.4

Solder Paste

5.5.4.1

Place

0.3 g of solder paste into the depression in

the test panel.

5.5.4.2

Allow

the test panels to remain in contact with the

bath until the solder specimen in the depression of the test

panel melts. Maintain this position for 60 ± 5 seconds before

removing the test panel from the bath. Cool the test panel to

room temperature.

5.5.4.3

Alternately,

process the panels through a reflow sol-

dering process using the temperature profile recommended

by the vendor.

5.6

Humidity Exposure

5.6.1

Carefully

examine the test specimen at 20X magnifica-

tion for subsequent comparison after humidity exposure.

Record observations, especially any discoloration (see 8.2).

5.6.2

Preheat

test panel to 40 ± 1 °C [104 ± 1.8 °F] for 30

± 2 minutes.

5.6.3

Humidity Soak

5.6.3.1

Place

the test specimen vertically in a preset humid-

ity chamber at 40 ± 1 °C [104 ± 1.8 °F] and 93 ± 2% relative

humidity.

5.6.3.2

Alternately,

the specimen may be placed in a tem-

perature humidity chamber and heated to 40 °C [1.8 °F] and

IPC-TM-650

Number

2.6.15

Subject

Corrosion,

Flux

Date

06/04

Revision

age2of3

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held

for 30 minutes. The humidity should then be increased to

93%RH.

5.6.3.3

Expose specimen to the above environment for 240

hours (10 days). M and H fluxes may be tested in the cleaned,

as well as uncleaned, condition. Specimens shall be cleaned

per the manufacturers instructions.

5.7

Evaluation

5.7.1

After

the exposure period, remove test specimens

from humidity chamber, examine at 20X magnification and

compare with observations noted in 6.5 (see 8.2).

5.7.2

For

purposes of this test method, the following defini-

tion of corrosion shall prevail: ‘‘A chemical reaction between

the copper, the solder, and the constituents of the flux resi-

dues, which occurs after soldering and during exposure to the

above environmental conditions.‘‘ Corrosion for this test is

classified as follows:

5.7.2.1

Minor Corrosion

Any

initial change of color, which

may develop when the test panel is heated during soldering,

is disregarded. Discrete white or colored spots in the flux resi-

dues or a color change to green-blue without pitting of the

copper or formation of excrescences is regarded as

minor

corrosion.

5.7.2.2

Major Corrosion

Any

initial change of color which

may develop when the test panel is heated during soldering is

disregarded. Subsequent development of green-blue discol-

oration with observation of pitting of the copper panel or

excrescences at the interfaces of the flux residue and copper

boundary, is regarded as

major

corrosion.

Notes

6.1

Questionable

results may be confirmed by analyzing the

suspected corrosion via Energy Dispersive X-ray Spectros-

copy (EDS) for the presence of copper.

6.2

Color

photos before and after the test are valuable tools

in identifying and documenting corrosion.

6.3

Safety

Observe

all appropriate precautions on MSDS

for chemicals involved in this test method.

IPC-TM-650

Number

2.6.15

Subject

Corrosion,

Flux

Date

06/04

Revision

age3of3

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