IPC-TM-650 EN 2022 试验方法.pdf - 第725页

1 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…

dressed

from the bottom to prevent flux residues from the

wire attachment from flowing onto the test patterns. With

mechanical fixtures, fixtures should be to the side. Insert the

limiting resistors in terminating leads 1, 3, and 5 of each pat-

tern.

5.2.2 Place the rack approximately in the center of the test

chamber. Route the wires to the outside of the chamber;

dress the wiring away from the test patterns. Ensure that

drops of condensation cannot fall on the specimens.

5.2.3

the chamber and allow all samples to stabilize

for 96 hours at the specific temperature and humidity. After

the 96-hour stabilization period, the initial insulation resistance

measurements shall be made using voltage in the range of 45

VDC to 100 VDC. Due to polarity, measurements should be

made between terminals 1 and 2, 3 and 2, 3 and 4, and 5 and

4, at the specific temperature and humidity with the current

limiting resistors placed in series with the test circuit. Termi-

nals 2 and 4 shall be at one potential, and terminals 1, 3, and

5 at the opposite potential.

5.2.4

Connect

the samples to the power supply with the

current limiting resistors placed in series with the test circuit,

and apply 10 VDC for the duration of the test. The test polar-

ity shall be the same as the measurement polarity used in

section 5.2.3.

5.2.5

After

500 hours of applied bias (596 hours total), dis-

connect the power supply and repeat the measurements per

5.2.3 with the specimens under test conditions.

5.3

Data Handling

The

average (geometric mean) insula-

tion resistance (IR

avg

)

is calculated from:

avg

=10

[

log

]

where,

= number of test points (10 minimum),

individual insulation resistance measurements

Where an assignable cause of low insulation resistance, which

is properly attributable to the materials of construction or to

the process used to produce the test board, can be found,

then such a value can be excluded from calculating the aver-

age.

Such assignable causes include:

• Contamination on the insulating surface of the board, such

as debris, solder splints, or water droplets from the condi-

tioning chamber

• Incompletely etched patterns that decrease the insulating

space between conductors by an amount greater than that

allowed in the appropriate design requirements drawing

• Scratched, cracked, or obviously damaged insulation

between conductors

A minimum of 10 test measurements is required for the test to

be valid.

5.4

Visual Examination

After

completion of the test, the

test specimens shall be removed from the test chamber and

examined, with back-lighting, at 10x magnification for evi-

dence of electrochemical migration (filament growth), discol-

oration, and corrosion.

Note: Localized electrochemical migration on one comb may

be caused by a testing anomaly.

Notes

6.1 Reference Documents

6.1.1 IPC-TR-476A

Electrochemical

Migration: Electrically

Induced Failures in Printed Wiring Assemblies

6.1.2

IPC-9201

Surface

Insulation Resistance Handbook

6.1.3

Telcordia GR-78-CORE

6.2 Specification of Test Conditions

Users

of this test

method will need to specify one (1) of the three (3)

temperature/humidity conditions called out in section 4.1.

Note that IPC-TR-476A recommends using 65°C, 85% RH.

IPC-TM-650

Number

2.6.14.1

Subject

Electrochemical

Migration Resistance Test

Date

09/00

Revision

age3of3

电子技术应用　　　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ

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.

age1of3

ASSOCIA

TION CONNECTING

ELECTRONICS INDUSTRIES

电子技术应用　　　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ

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

电子技术应用　　　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ