IPC-TM-650 EN 2022 试验方法.pdf - 第276页

1 Scope This test method assesses the relative activity of liquid fluxes using a wetting balance. 2 Applicable Documents ISO 1634 IPC J-STD-004 Requirements for Soldering Fluxes 3 Test Specimen 3.1 The test specimen shal…

5.2.1

Fluxing

Immediately

after removal from the desicca-

tor, metal surfaces shall be cleaned by light abrasion, or other

suitable methods. Flux with rosin flux conforming to type R,

MIL- F-14256. Let drain in a vertical position.

5.2.2

Stressing

Within

10 minutes of removal from desic-

cator, float the specimen for 10 + 1, –0 seconds on the sur-

face of a solder bath maintained at the specified temperature,

measured at a depth of 25.4 mm [1.0 in] below the surface.

The specimens shall be kept in intimate contact with the sol-

der surface and agitated by gentle downward pressure using

tongs or equivalent.

Note:

Very

thin laminates, typically under 0.5 mm [0.020 in]

thick, are prone to bowing or curling upon contact with solder.

The following handling instructions apply:

a. For etched specimens, mount each specimen using

staples to a piece of corrugated board (‘‘cardboard’’)

approximately 75 x 75 mm [3.0 x 3.0 in].

b. For unetched single-clad specimens, mount each speci-

men to a 75 x 75 mm [3.0 x 3.0 in] piece of corrugated

board (‘‘cardboard’’) by slipping two opposite edges into

slits cut parallel and 38.1 mm [1.5 in] apart in the card-

board.

c. Unetched double-clad specimens including those of

unequal cladding thicknesses, do not require mounting.

5.2.3

The

specimens shall be removed from the bath and

allowed to cool to room temperature. Mounted specimens

may be removed from the supporting cardboard. Clean the

flux from the specimens using appropriate solvent.

5.3

Evaluation

5.3.1 Etched or Unclad Specimens

Examine

the speci-

mens by normal or corrected 20/20 vision, using backlighting

if necessary. Record the presence of charring, surface con-

tamination, loss of surface resin, resin softening, delamination,

blistering, weave exposure, propagation of imperfections,

measling, crazing, or voids.

Determine the number and dimension of any voids using 4X

minimum magnification; for referee purposes, 10X magnifica-

tion shall be used.

5.3.2

Clad Specimens

The

specimen shall be examined

for any evidence of blistering, delamination or other damage.

During the solder exposure, any apparent event that is evi-

dence of damage, such as the specimen exhibiting a ‘‘bump’’

felt through the tongs, shall be recorded as a sign of possible

delamination.

5.3.3

For

referee purposes, the etched or unetched speci-

mens shall then be microsectioned in accordance with IPC-

TM-650, Method 2.1.1 (except there are no plated-through

holes). The microsections shall be examined for degradation

(see 5.6.1) at a magnification of 100X and referee inspection

at 200X.

5.4

Report

Any

observed degradation to the unetched or

etched or unclad specimens shall be reported. The number

and location of voids shall be reported for each specimen.

Results of referee microsection examination will take prece-

dence over visual examination.

6.0 Note

Automatic

(gang mounting) microsectioning tech-

niques may be used.

6.1

Desiccator Conditions

The

Test Methods Task Group

determined that a great majority of test laboratories are unable

to consistently hold the Relative Humidity in a desiccator to

less than 20%. Based on data from participating company lab

management, the lowest practically feasible RH for use with

the affected IPC Test Methods is 30% maximum.

IPC-TM-650

Number

2.4.13.1

Subject

Thermal

Stress of Laminates

Date

12/94

Revision

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Scope

This

test method assesses the relative activity of

liquid fluxes using a wetting balance.

Applicable Documents

ISO 1634

IPC J-STD-004

Requirements

for Soldering Fluxes

Test Specimen

3.1

The

test specimen shall be a copper coupon complying

with ISO 1634-CU-ETP Condition HA. The width shall be 6.0

± 0.25 mm [0.236 ± 0.00984 in]; the length should be 25.0 ±

1.0 mm [0.984 ± 0.0394 in] or as appropriate to the test

equipment. The thickness shall be 0.5 ± 0.05 mm [0.0197 ±

0.00197 in].

3.2

minimum of 50 ml of the liquid flux to be tested.

Apparatus and Reagents

4.1 Apparatus (see Figure 1).

4.2

meniscus force measuring device (wetting balance)

which includes a temperature-controlled solder pot containing

solder maintained at 245 ± 3 °C [473 ± 5.4 °F].

Note: Reaction rate is very sensitive at this temperature.

Solder composition shall be Sn60/Pb40 or Sn63/Pb37.

4.3

chart recorder, data logger, or computer capable of

recording force as a function of time with a minimum recorder

speed of 10 mm/s [0.394 in].

4.4

mechanical dipping device able to produce an immer-

sion and emersion rate of 20-25 mm [0.787-0.984 in] per

second to a depth of 6.0 ± 0.1 mm [0.236 ± 0.00394 in], with

a dwell time of 5.0 ± 0.5 seconds.

Procedure

5.1 Preparation

5.1.1

Degrease

the test coupon by immersing it in a suitable

solvent. Use a 10 ± 1% fluoroboric acid dip to clean the cou-

pon.

IPC-24142-1

Figure

1 Wetting Balance Apparatus

▼

Chart

Recorder

Signal

Conditioner

Controls

Solder

Bath

Heater

Clamp

Copper

Coupon

Relative

Motion

LVDT

(Transducer)

▼

2215

Sanders Road

Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.4.14.2

Subject

Liquid

Flux Activity, Wetting Balance Method

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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5.1.2

Rinse

the coupon with deionized water, then dry the

coupon.

5.2

Test

5.2.1

Immerse

the coupon in the liquid flux at room tem-

perature to a minimum depth of 10.0 mm [0.394 in].

5.2.2 Immediately

drain off excess flux by standing the

specimen vertically on a clean filter paper for 1-5 seconds.

5.2.3

After

partial drying, mount the coupon in the test

equipment.

5.2.4

Skim

(remove dross from) the surface of the molten

solder just prior to immersing the specimen in the solder.

5.2.5

Hold

the specimen 3.0 mm [0.118 in] above the sol-

der pot for approximately 10 ± 1 seconds. Start the test.

Immerse the specimen to a depth of 5.0 ± 0.1 mm [0.197 ±

0.00394 in], using an immersion and emersion rate of 20-25

mm [0.787-0.984 in] per second and a dwell time of 5.0 ± 0.5

seconds.

5.2.6

Record

the wetting curve during the test.

5.3

Evaluation

Use

the wetting balance curve recorded

during the test to determine the following flux activity param-

eters:

5.3.1

Tw,

the wetting time. This is the time at which the

wetting curve crosses the corrected zero axis, measured from

the start of the test (see Figure 2).

5.3.2

The

maximum wetting force, Fmax, with the zero axis

corrected for buoyancy (see 6.2 and Figure 2).

Notes

This

test method can be useful in requalifying

materials that have exceeded the recommended shelf life. In

IPC-24142-2

Figure

2 Wetting Balance Curve

TIME

▼

FORCE (

▼

Instrument Zero

Corrected Zero

Fmax

IPC-TM-650

Number

2.4.14.2

Subject

Liquid

Flux Activity, Wetting Balance Method

Date

06/04

Revision

age2of3

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