IPC-TM-650 EN 2022 试验方法.pdf - 第667页

1 Scope This test method is to characterize fluxes by determining the degradation of electrical insulation resistance of rigid printed wiring board specimens after exposure to the specified flux. This test is carried out…

5.5.4 Apply a reverse polarization potential of 500 ± 50 volts

dc with the resistance meter for one minute. Next, take the

measurements at 500 volts dc ± 50 volts dc between each

pair of terminals, 1 to 2, 2 to 3, 3 to 4, and 4 to 5, of the test

specimen.

5.5.5 Note any reason(s) for deleting values, i.e., scratches,

condensation, bridged conductors, etc.

5.6 Evaluation

5.6.1

The values to be reported shall only be the readings

taken in 5.5 through 5.5.5, which are the ‘‘After Recovery’’

values. See Figure 2 for a typical IR plot.

5.6.2 After completion of all electrical testing, the test speci-

mens shall be examined for measling, blisters, delamination,

or other forms of degradation, following 24 hour stabilization

at laboratory ambient temperatures.

6 Notes

6.1

Documented alternative cleaning procedures may be

implemented if there is a concern that scrubbing will adversely

affect test results.

6.2 A failure due to measling, blistering, delamination, or any

other form of degradation, may be due to several factors, and

not necessarily due to inferior coatings.

IPC-2632-2

Figure 2 Typical IR and MIR plot

READING

LOG OF I. R.

1 2

IR Initial = 3.57E+014 ohms

M & IR = 6.47+ 010 ohms

2 hr Recov = 4.20E+013 ohms

24 hr Recov = 4.49+013 ohms

IPC-TM-650

Number

2.6.3.2

Subject

Surface Insulation and Moisture Resistance, Copper Clad

Flexible Dielectric Material

Date

8/14/15

Revision

Page3of3

Scope

This

test method is to characterize fluxes by

determining the degradation of electrical insulation resistance

of rigid printed wiring board specimens after exposure to the

specified flux. This test is carried out at high humidity and heat

conditions.

Applicable Documents

IPC-B-24

Surface

Insulation Resistance Test Board

IPC-A-600

Acceptability

of Printed Boards

IPC

J-STD-004

Requirements

for Soldering Fluxes

IPC-9201

Surface

Insulation Resistance Handbook

Test Specimen

minimum of 10 ml of liquid flux, a rep-

resentative container of solder paste, cored wire, paste flux, or

extracted solder preform flux. The reflow/extraction process

should be carried out in accordance with IPC J-STD-004.

3.1

Comb Patterns

Use

the IPC-B-24 test pattern (see

Figure 1), which consists of four comb patterns per coupon.

Each individual comb has 0.4 mm lines and 0.5 mm spacing.

The metallization shall be unpreserved bare copper.

3.2

Laminat

The

laminate material for this test shall be

FR-4 epoxy-glass.

Apparatus

4.1

clean test chamber capable of programming and

recording an environment of 25 +10/-2 °C [77 + 18/-3 °F] to

at least 85 ± 2 °C [185 ± 3.6 °F] and 20% ± 5% to 85% ± 2%

relative humidity. A salt solution and desiccator may be used

to maintain humidity if a tight temperature control is main-

tained on the chamber.

4.2

power supply capable of producing a standing bias

potential of 45-50 volts DC with a tolerance of ± 10%.

4.3

resistance meter capable of reading high resistance

(10

ohms)

with a test voltage of 100 volts, or an ammeter

capable of reading 10

-10

amps

in combination with 100 volts

DC power supply.

4.4

Three

2000 ml beakers.

4.5

Exhaust

ventilation hood.

4.6

Metal

tongs.

4.7 Soft

bristle brush.

4.8

Deionized

or distilled water (2 megohm-cm minimum

resistivity recommended).

4.9

Drying

oven capable of maintaining at least 50 °C

[122 °F].

Procedure

5.1 Test Conditions

All

fluxes will be tested at 85 ± 2 °C,

[185 ± 3.6 °F], 85 ± 2% relative humidity for 168 hours.

5.2

Specimen Preparation

There

shall be three test cou-

pons for each liquid flux to be tested in the cleaned state

(Table 1, Sample Group A). When testing liquid fluxes which

are intended to remain in the uncleaned state, six test cou-

pons are required. Three uncleaned test coupons shall be

soldered pattern side down (Table 1, Sample Group B) and

three shall be soldered pattern side up (Table 1, Sample

Group C).

Solder paste coupons shall be reflowed pattern side up and

either cleaned (Table 1, Sample Group D) or not cleaned

(Table 1, Sample Group E).

IPC-2633-1

Figure

1 Test Pattern from IPC-B-24

2215

Sanders Road

Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.6.3.3

Subject

Surface

Insulation Resistance, Fluxes

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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addition, there shall be at least two unprocessed control

coupons for comparison purposes (Table 1, Sample Group F).

5.2.1

Positive,

permanent and noncontaminating identifica-

tion of test specimens is of paramount importance. (For

example, a vibrating scribe.) Permanent ink may be used on

the back side of the test coupon if areas beneath conductors

are avoided.

5.2.2

Visually

inspect the test specimens for any obvious

defects, as described in IPC-A-600. If there is any doubt

about the overall quality of any test specimen, the test speci-

men should be discarded.

5.2.3

Clean

each test or control coupon with deionized or

distilled water and scrub with a soft bristle brush for a mini-

mum of 30 seconds. Spray rinse thoroughly with deionized or

distilled water. Rinse the cleaned area thoroughly with fresh

2-propanol.

An alternative cleaning method is to place the test coupon in

an ionic contamination tester containing 75% 2-propanol,

25% deionized water and process the solution until all ionics

have been removed.

During the remainder of the specimen preparation, handle test

specimens by the edges only, and use noncontaminating rub-

ber gloves.

5.2.4

Dry

the cleaned boards for two hours at 50 °C

[122 °F].

5.2.5 If

boards are to be stored before treatment, place the

boards in Kapak® bags or other contamination-free contain-

ers (do not heat seal) in a desiccator.

5.3

Sample Preparation

Flux

application and soldering.

5.3.1

Liquid Flux or Flux Extract

Coat

the test pattern

with a thin coating of the liquid flux or flux extract under test.

5.3.1.1

Preheat

the flux coated test coupon using the tem-

perature profile recommended by the vendor. If no profile is

available, preheat the test coupon in an oven set at a tem-

perature such that the test coupon reaches a temperature of

140 °C [284 °F] in 30 to 45 seconds.

5.3.1.2 Immediately

expose the test coupon to solder by

floating the fluxed comb patterns of the test specimen face

down on the solder pot at 245-260 °C [473-500 °F] for4±1

seconds. Be sure that all dross is removed from the solder pot

surface just before contact with the specimen.

5.3.1.3

Alternatively,

the specimen can be wave soldered

face down at 245-260 °C [473-500 °F] and a conveyor speed

with a contact time of3±1seconds.

5.3.1.4

For

fluxes to be tested in the uncleaned state, a

second set of test patterns shall be fluxed and floated pattern

up on the solder pot or passed pattern up over the solder

wave.

5.3.2 Solder Paste or Paste Flux

Stencil

print the solder

paste or paste flux onto the comb pattern using a 0.15 mm

[0.00591 in] (6 mil) thick stencil (the IPC-A-24 artwork con-

tains the stencil design).

5.3.2.1

The

samples shall be run through a reflow soldering

process using the temperature profile recommended by the

vendor.

5.3.3

Cored Wire

Using

a clean fine-tip soldering iron

apply the cored wire to the comb patterns being careful not to

bridge the conductors. The iron temperature should be as

specified by the cored wire vendor.

5.4

Cleaning of Samples

5.4.1

After

exposure to flux and solder, samples to be

tested in an uncleaned state shall be tested as outlined in 5.5

through 5.6.1.

5.4.2

After

exposure to flux and solder, samples to be

tested in the cleaned state shall be cleaned using one of the

able 1 Coupons for SIR Testing

Sample

Group

Flux/

Solder

Clean

Number of

Coupons

Yes Yes 3

B Yes No 3

C Yes No 3

D Yes Yes 3

E Yes No 3

FNoNo2

= Pattern down/cleaned

B = Pattern down/not cleaned

C = Pattern up/not cleaned

D = Solder paste/reflow/cleaned

E = Solder paste/reflow/not cleaned

F = Control (precleaned, unprocessed)

IPC-TM-650

Number

2.6.3.3

Subject

Surface

Insulation Resistance, Fluxes

Date

06/04

Revision

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