IPC-TM-650 EN 2022 试验方法.pdf - 第88页

Figure 3 Microhm Meter Calibration Curves IPC-TM-650 Number 2.2.13.1 Subject Thickness, Plating in Holes Microhm Method Date 1/83 Revision A P a g e4o f4 电子技术应用ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ

NOTE:

steady reading indicates that the probes am mak-

ing good contact. Trial settings to obtain the minimum resis-

tance value will indicate when the probes are properly located

over the interconnection.

5.2.5

poor electrical contact is evidenced, relocate the

probes until a minimum resistance is indicated.

NOTE:

During the microscopic inspection (30X) of the edges

of the plated-through hole and the adjacent areas on the ter-

minal area, there shall be no detectable damage to the sur-

faces by contact with the probes during testing. In the

absence of such surface defects, the microhm testing can

assuredly be considered nondestructive.

5.2.6

Read

and record the microhm value.

5.2.7

Compare

the microhm value with the plating thickness

of the standardization curve as illustrated in Fig. 3. The theo-

retical curves shown in Fig. 3 indicate to within 0.2-rail thick-

ness the plating in the through connection and for all practical

purposes are representative of the resistance-plating thick-

ness relationships encountered in practice.

NOTE:

This

comparison shall indicate if the plating thickness

of the through connection meets the acceptable thickness

requirements

5.2.8

When

this method is used, any reading above the

specified allowable microhm reading shall be reason for fur-

ther investigation of the defect for conformance to the require-

ments of the applicable fabrication specification.

5.2.9

Plating

thickness curves shall be generated by the

user.

6.0

Resistance Curves

6.1

Curves

for the resistances of plated-through holes of

three different diameters in 1/16’’ printed wiring boards are

presented in this test method (Fig. 3). Over coatings of gold,

tin-lead, etc., can have an effect on the micro-ohm readings

depending on the electrical resistance relative to the copper.

Resistivity of tin-lead is approximately ten times that of cop-

per, while gold is of the same resistivity.

6.2

eliminate material and equipment variables, the user

should develop thickness-resistance curves for his particular

condition based on metallographic cross-section measure-

ments (TM-650 Method 2.2.13). These curves may be used

as guides for acceptance of product.

IPC-TM-650

Number

2.2.13.1

Subject

Thickness,

Plating in Holes Microhm Method

Date

1/83

Revision

age3of4

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Figure

3 Microhm Meter Calibration Curves

IPC-TM-650

Number

2.2.13.1

Subject

Thickness,

Plating in Holes Microhm Method

Date

1/83

Revision

age4of4

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1.0

Scope

method for determining whether or not the

powder in a solder paste complies with the relevant powder

type. The ASTM B-214 standard screen powder size distribu-

tion method has been found to be acceptable.

2.0

Applicable Documents

ASTM E11

BS.410

DIN 4188

ISO 565

ISO 3310

3.0 Test Specimen

Approximately

150 grams of solder paste

4.0

Equipment/Apparatus

Vibratory

test sieving machine

Test sieves to BS.410, ASTM E11, DIN 4188, or ISO 565 and

ISO 3310 with mesh openings of 150, 75, 45, 38, 25 and 20

micrometers

Sieve bottom receiver and lid

Balance (scale) with an accuracy of 0.01 g

Beaker 400–600 ml

Watch glass

Solvent

Acetone

Spatula

5.0

Procedure

5.1 Preparation

5.1.1

Wait,

if necessary, until the solder paste is at room

temperature.

5.2

Test

5.2.1

Homogenize

the paste by stirring with the spatula.

5.2.2

Weigh

paste containing approximately 110 g of solder

alloy into the carefully cleaned beaker.

5.2.3

Add

approximately 50 ml solvent.

5.2.4

Stir

the mixture with the spatula so that the flux in the

paste can dissolve in the solvent.

5.2.5

Cover

the beaker with the watch glass.

5.2.6

Let

the beaker with the watch glass stand until the

solder powder settles.

5.2.7

Decant,

carefully, as much as possible of the fluid

without losing any of the solder powder.

5.2.8 Repeat

the extraction procedure five times, using 50

ml solvent for each extraction.

5.2.9

Add

approximately 50 ml acetone to the washed sol-

der powder and stir with the spatula to assist in drying.

5.2.10

Let

the solder powder settle.

5.2.11

Decant,

carefully, as much as possible of the

acetone.

5.2.12

Repeat

the acetone wash 2 additional times.

5.2.13

Allow

the powder to dry at ambient temperature until

the weight is constant.

5.2.14

Weigh

test sieves, with mesh opening sizes appro-

priate for the type of powder being tested, and the sieve bot-

tom receiver. Typical sieves required are shown in Table 1.

able 1 Screen Opening

ype 1 150 75 20

Type 2 75 45 20

Type 3 45 25 20

Type 4 38 20

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062

IPC-TM-650

TEST

METHODS MANUAL

Number

2.2.14

Subject

Solder

Powder Particle Size Distribution—Screen

Method for Types 1-4

Date

1/95

Revision

Originating Task Group

Solder Paste Task Group (5-24b)

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.

age1of2

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