GOST 23904-79

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  ГОСТ 23904-79

GOST 23904−79 Pike. Method of determining wettability of solder materials

GOST 23904−79

Group B09

STATE STANDARD OF THE USSR

PIKE. METHOD OF DETERMINING WETTABILITY OF SOLDER MATERIALS

Brazing and soldering.
Method for determination of materials wetting with solders

Valid from 01.07.1980
before 01.07.1985*
_______________________________
* Expiration removed
by the decree of Gosstandart of the USSR
from 22.12.89 N 4020 (IUS N 4, 1990). -
Note the manufacturer’s database.

DEVELOPED by the State Committee of USSR on standards by the Academy of Sciences of the USSR **

PERFORMERS**

N. N. Sirchenko, PhD. tech. of Sciences; Yu. Naidich, member.-Q. USSR Academy of Sciences, Prof., doctor of engineering. Sciences; A. V. Savchenkov, V. S. Zhuravlev, Cand. tech. Sciences; perevertaylo, V. M., Cand. chem. Sciences; L. I. Lambert **

MADE with the USSR State Committee for standards**

Zam. Chairman S. P. Malyshkov **

APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards of 23 November 1979, N 4495 **
_________________
** Information cited from the official publication, Moscow: Publishing house of standards, 1980. — Note the manufacturer’s database.

REPRINTING. April 1982


This standard covers the method for determining the wetting of the solder materials with the following characteristics:

the regional corner of wetting and spreading area;

initial speed of wetting time and spreading (for solders with 723 K).

The standard used to evaluate material compatibility with soldering, design of technological process of soldering and optimize its settings, and the development of new solders and fluxes.

1. DETERMINATION OF WETTING AT THE BOUNDARY CORNER AND SQUARE SPREADING

1.1. Sampling

1.1.1. For testing, you should apply plate having a size of 40x40 mm or discs of diameter 40 mm of the brazed material.

1.1.2. The thickness of the plates or discs should be 0.5−3.0 mm. thickness 3 mm maximum allowed machining of the part, not tested.

1.1.3. For the tests to use a billet of solder in the form of a cylinder or a cube having a metered capacity of 64 mm. The mass of solders depending on their density in the reference Appendix 1.

1.1.4. When using solders containing Ag, Au, Pt, Pd and other precious or rare metals, sizes of samples for testing should be 20x20 mm or 20 mm in diameter, and a metered amount of solder 16 mm.

1.1.5. The number of samples for testing should be at least three for each combination of materials, solder and flux, soldering.

1.2. Equipment and instruments

1.2.1. Testing is recommended for the installation, schematic diagram of which is shown in hell.1.

Installation diagram for testing

1 — drop of solder; 2 — a sample of brazed material; 3 — substrate for mounting the sample;
4 — thermocouple; 5 — heating device; 6 — camera (when testing in a medium or vacuum);
7 — light source; 8 — microphotonic (magnifier); 9 — screen; 10 — lens

Damn.1

The installation should provide:

the horizontal test sample;

the possibility of creating the necessary environment or vacuum in the test period;

alignment and focusing of a clear image of a drop of solder on the screen;

uniform heating of the sample to a predetermined temperature;

the lack of vibration.

A list of recommended equipment and devices is given in reference 2 below.

1.2.2. Temperature measurement during the tests to produce thermocouples according to GOST 6616−74 and devices according to GOST 9245−79 of accuracy class not less than 0.05.

1.2.3. To determine the wetting angle should be applied to photo and video. Speed filming 16−1500 frames per second depending on the speed of spreading of the solder.

1.2.4. Measurement of the wetting angle on the photo or film must be made in the tool microscopes.

1.3. Preparation for testing

1.3.1. The surface of the samples and solder should be prepared in accordance with the technological process of manufacturing brazed structure. In the absence of data method of surface preparation to establish empirically. Allowed testing the materials in the delivery condition by removing grease and moisture.

1.3.2. The solder should be placed in the center of the horizontally positioned plate. The levelness of the ground for setting plates to check the level.

1.3.3. The working end of the thermocouple should be fastened in the center of the outside surface of the sample methods, providing a reliable thermal contact according to the devil.2.

Damn.2

1.3.4. Samples of the marking of the batch number or the conditional index for the non-working parts in any way, ensure the marking after testing.

1.4. Testing

1.4.1. Samples should be heated in a gas atmosphere, in vacuum or flux in accordance with the technological process. In the absence of data protection it is necessary to choose depending on the grade of material and solder.

1.4.2. When testing with the flux volume should be no more than 400 mmfor samples of 40x40 mm and not more than 100 mmfor samples 20x20 mm. Flux should be applied according to the adopted technology.

1.4.3. The wetting angle must be documented in the testing process in accordance with claim 1.2.3. Allowed direct measurement of the angle on the screen.

1.4.4. Wetting angle is fixed when the solder of the following values of temperature:

initial melting point (3−5 °C above the solidus);

full melting (3−5 °C above liquidus);

the soldering temperature.

Fixing other points is made depending on the tasks.

1.4.5. In the absence of appropriate equipment allowed the measurement of the wetting angle after cooling of the sample.

1.5. Processing and calculation of results

1.5.1. Measurement of the wetting angle must be done in the following order:

in the picture or projection of drops draw a tangent at the point of intersection of the contour drops with the sample surface, as shown in hell.3;

to measure the tangent angle according to claim 1.2.4.

Damn.3

1.5.2. For each projection drops measured contact angle with the left and right sides. Measurement error should not exceed 5 degrees.

1.5.3. Calculation of the wetting angle of this drop should be carried out according to the formula

, (1)

where , is the measured values of wetting angle with the left and right sides, respectively.

1.5.4. The wetting angle for a given combination of «solder — brazed material» should be determined by the formula

, (2)

where , , …,  — values of wetting angle for each drop;

 — the number of samples.

1.5.5. When used for measuring protractor or stencil image system «drop-plate», obtained at photos or film, you should also increase at least five times, projecting the image on the screen.

1.5.6. To reduce the error from the imperfections of the drop shape on the cooled sample, the wetting angle should be determined as follows:

measure at least three projections, one drop of values and to find their average values;

to calculate the wetting angle of this drop as the average value between and by the formula (1) where and  — average values of the wetting angle of the left and right sides of the drops;

to determine the wetting angle for the combination «material-solder» in the formula (2).

1.5.7. The area of spreading of the solder should be counted after cooling of the sample as the arithmetic mean of the three obtained results of tests. Measuring the area of the spreading should be done with instruments or devices that provide a measurement error of up to 5.0% of the measured area.

1.5.8. The criteria for wetting of the solder material should be considered:

the value of the wetting angle , determined at the test temperature or refrigerated (note that the error in the determination of the contact angle on a refrigerated sample can be 10−15%);

the area of spreading of the solder on the surface of the sample.

1.5.9. Tests are considered invalid for violation of the composition of the medium during testing, failure of the thermocouple during heating, ahorizontal wetted surface.

1.5.10. The test results of each sample should be recorded in the test report, the form of which is given in the mandatory Annex 3.

2. DETERMINATION OF WETTING ON THE INITIAL SPEED AND THE TIME SPREADING

2.1. Sampling

2.1.1. For tests should be applied:

plate brazed with a material thickness of from 0.1 to 1.0 mm, a width of 25 mm and a length of 30 mm. Preferred size 30х10х0,1;

wire diameters of 0.3 mm, the Preferred diameter of 1.0 mm.

2.1.2. Bath mirror with solder should be of diameter not less than 30 mm, and the mass of solder in the bath must maintain constant temperature when immersed sample with a deviation of not more than 1°.

2.1.3. Sampling should comply with the requirements of clause 1.1.5 of this standard.

2.2. Equipment and instruments

2.2.1. Tests should be conducted on the device, a schematic diagram is given on features.4. A list of recommended equipment is specified in reference 2 below.

The schematic diagram to determine the initial velocity and time of wetting

1 — bath with solder; 2 — sample; 3 — holder; 4 spring suspension; 5 — pin;
6 — sensor, which converts the movement in force; 7 — tensometric amplifier; 8 — digital oscilloscope

Damn.4

2.2.2. Equipment used for testing must meet the following conditions:

2.3. Preparation for testing

2.3.1. Before the test, should conduct a calibration device for determining the forces for retracting the sample in the melt, using the weights weighing from 10 to 200 mg.

2.3.2. The sample whose surface is prepared in accordance with claim 1.3.1 should be fixed in the holder suspended from a spring suspension.

2.3.3. To compensate for the mass of the sample using an electric circuit device.

2.3.4. To verify that the temperature of the solder in the bath temperature tests.

2.4. Testing

2.4.1. Lower the sample into the solder to a depth of 1−3 mm (the preferred depth — 2 mm). Immersion of the sample in the melt must be observed perpendicular to the lateral surface of the plane mirror of the bath.

2.4.2. The interaction forces arising from the immersion of the sample should be recorded on the tape recording device.

2.4.3. The typical form of the recorded curve is shown in hell.5.

 — time to start wetting;  — net time wetting;  — time for complete wetting;
the force of wetting (equilibrium);  — the power of separation of the solder from the sample when lifting;

Stage 1 — the process of obtaining a negative meniscus radius of curvature is directed from the melt (weight loss of the sample due to capillary pressure and the hydrostatic buoyancy replaced by a model of part of the solder); stage 2 — the process of moving the solder side of the sample (the radius of the meniscus changes the direction in the direction of the fluid); stage 3 — the maximum rise of the meniscus of the solder (equilibrium system); stage 4 — rise of the sample (separation of the sample from the solder). The nature of the curve depends on the shape of the sample and the rate of rise

Damn.5

2.5. Processing and calculation of results

2.5.1. Initial speed of wetting is determined by the angle measurement and counting of its tangent between the tangent to the curve at the point and perpendicular to the ordinate axis (Fig.5).

2.5.2. The timing of the wetting should be the curve in the tape recording device in accordance with the devil.5.

2.5.3. The calculation of other characteristics of wetting obtained in the tests given in the informational Appendix 4.

ANNEX 1 (reference). The mass of the metered volume of solder depending on its density and dimensions of the test specimen

ANNEX 1
Reference

ANNEX 2 (informative). A list of recommended equipment and devices to conduct tests to determine the wetting of the solder material

ANNEX 2
Reference

APPENDIX 3 (obligatory). Protocol testing of samples to determine the wetting

APPENDIX 3
Mandatory

Protocol N
testing of samples to determine the wetting

_______________
* Numbering corresponds to the original. — Note the manufacturer’s database.

Table 1

Table 2

Signature:

ANNEX 4 (reference). The calculation of additional characteristics in determining the wettability of solder materials

ANNEX 4
Reference

For testing performed in accordance with sec. 1 and 2 of this standard by calculation, we can obtain the following additional characteristics of the process of wetting.

The value of the wetting angle in the parameters drop of solder on the sample (mass of solder to 0.2 g) by the formula

,

where  — height of the drops of solder;

 — the volume drops.

The value of adhesion tension by the formula

,

where is the adhesion tension;

 — the surface tension of the solder, N/m;

the force of wetting (see the devil.5 of this standard), N;

the wetting perimeter (twice the sum of the width and thickness of the sample).

A value of adhesion tension can be obtained: the value of the height of lifting of solder in the capillary gap of the given width according to the formula

,

where is the density of the solder (use the density values at room temperature);

— the acceleration of gravity;

— the width of the capillary gap.

The value of the wetting angle by the formula

,

where is the force of wetting (see the devil.5 of this standard);

 — the power of separation of the solder from the pattern when it goes up (see the devil.5 of this standard);

 — amendment on the hydraulic buoyant force equal to the weight of solder displaced by the specimen.

The power value calculated by the formula

,

where is the density of the solder, kg/m;

 — immersion depth of the specimen, m;

 — cross-sectional area of the specimen, m;

 — the acceleration of gravity, m/s.