Determine the solderability of the lead-out terminals of any shape of components and devices. It is particularly suitable for arbitration tests and for evaluating the solderability of the lead-out terminals of components and devices that cannot be quantitatively tested by other methods. GB/T 2423.32-1985 Basic environmental testing procedures for electrical and electronic products Wetting weighing method Solderability test method GB/T2423.32-1985 Standard download decompression password: www.bzxz.net

1Purpose
National Standard of the People's Republic of China
Basic environmental testing proceduresfor electric and electronic productsSolderability testing by the wetting balance methodUDC 621.3
:620.179.2
GB2423.32--85
Determine the solderability of the lead-out terminals of any shape of components and devices. It is especially suitable for arbitration tests and evaluation of the solderability of the lead-out terminals of components and devices that cannot be quantitatively tested by other methods. 2 Test Overview
The lead-out terminals of components and devices (hereinafter referred to as test samples) are suspended from the scale bar of a sensitive scale (usually a spring system) and immersed in the molten solder maintained at a specified temperature to a specified depth. At the same time, the resultant forces of buoyancy and surface tension acting on the immersed test sample in the vertical direction are measured by a sensor and converted into signals. The signal is continuously recorded as a function of time by a high-speed characteristic curve recorder, and then the curve is compared with the curve obtained from a test sample with the same properties and size and which can be completely wetted.
Description of test equipment
The principle block diagram of this test method is shown in Figure 1: t
Scale beam fulcrum and spring
Test sample
Sensor
Lifting mechanism
Promulgated by National Bureau of Standards on May 15, 1985
Sample equipment
Signal amplifier
Curve recorder
Controller
Implementation on February 1, 1986
GB 2423.32--85
As long as the requirements of Appendix A are met, any other equipment that can measure the resultant force acting on the test sample in the vertical direction is allowed to be used 4 Preparation of test samples
During the preparation of the test samples, cleaning is generally not carried out, so the test surface of the test sample must be protected from contamination, especially not allowed to be touched by fingers. Only when the relevant standards require it, it is allowed to immerse in a neutral organic solvent at room temperature for cleaning.
5 Test conditions and procedures
5.1 Test conditions
5.1.1 Solder
The solder used shall comply with the provisions of Appendix B of GB2423.28-82 "Basic environmental test procedures for electric and electronic products Test T: Soldering test method".
5.1.2 Flux
The flux used shall comply with the provisions of Appendix C of GB2423.28. 5.1.3 Temperature of solder
The temperature of the solder in the solder bath to be tested shall be 235±2℃. 5.2 Test procedures
5.2.1 Heating
Heat the solder in the solder bath and keep it at the specified temperature. 5.2.2 Solder Dipping
Mount the test sample on the fixture and immerse the entire surface to be tested in the flux at room temperature. Immediately afterwards, place the test sample vertically on a clean filter paper for 1 to 5 seconds to remove excess flux. 5.2.3 Preparation before Dipping
Hang the test sample vertically above the solder tank so that its lower edge is 20±5mm away from the solder surface and stay for 30±15s so that most of the solution in the flux can evaporate before the test begins. During this drying period, the suspended test sample should be adjusted to the required zero position, and the recording pen should also be adjusted to zero position. Immediately before the test begins, use a scraper made of suitable material to scrape off the oxide on the solder surface. 5.2.4 Dipping
Immerse the test sample in the molten solder at a speed of 20±5mm/s to the specified depth, keep it at this depth for the specified time, and then remove it at a speed of 20±5mm/s. In this way, the force-time curve and (or) related data are obtained. 6 Test results
6.1 Force-time curve
The curve can be expressed in two forms, the difference being only in the polarity of the force reading. This standard stipulates (see Figure 2) that the upward force is positive and the downward force is negative. If the force at point C is the same as the force at point B, stable wetting is indicated. If the ordinate value at point C is greater than that at point B, some unstable factors appear in the wetting. 329
6.2 Meaning of each point on the curve
GB2423.32—85
6.2.1t. is the time when the solder surface begins to contact the test sample, and is the starting point of force and time. 6.2.2 Point A is the point where the force acting on the test sample is equal to the calculated buoyancy, and the contact angle is 90 at this time. The immersion depth in the buoyancy calculation refers to the depth below the original solder plane. The horizontal dotted line through point A is the buoyancy line, and all forces are measured with reference to the buoyancy line.
6.2.3 Point B is the point when the force acting on the test sample is zero. 6.2.4 Point M is the point indicating the force at time tm specified in the relevant standard. 6.2.5
Point B is the point indicating the maximum downward force obtained within the specified immersion cycle. Point C is the point at the end of the specified immersion cycle. For the same test sample, the force values ​​at points C and B may be the same. 6.3 Wetting force
6.8.1 Theoretical wetting force
In order to evaluate the solderability of the test sample, the actual wetting force (Factual) obtained after eliminating the influence of buoyancy (F) should be compared with the theoretical wetting force (Ftheoretical) or reference wetting force. This theoretical wetting force is obtained under the surface tension constant of the molten solder under the test conditions specified in this standard and under the condition of complete wetting. The theoretical wetting force, buoyancy and actual wetting force are obtained by the following formulas: Ftheoretical = -0.4LmN)
Where: L--the circumference of the immersed part of the test sample, mm. (1)
Note: This formula is only applicable when the cross section of the test sample near the curved liquid surface is constant in its length direction. The constant value in the formula depends on the type of solder alloy, soldering temperature and flux used. The coefficient value of 0.4N/m is only applicable to the conditions specified in this test. Fz = 0.08V
Where: .
--Volume of the immersed part of the test sample, mm3F=Fu-F
（3）
GB 2423.32-85
For test samples with complex shapes that cannot calculate the theoretical wetting force, in practical terms, a reference wetting force is used to provide a reference for comparison of test results. The following procedure should be followed when determining the reference wetting force. Take one test sample from the samples taken for the test and pre-solder it under the optimal conditions using the active flux specified in GB2423.28-82. The pre-soldering can be carried out on a wetting weighing test equipment under the same conditions as used in the wetting test. The pre-soldering procedure should be repeated on the same test sample until the maximum force read does not increase further. The reference wetting force is this maximum force. 6.4 Test Requirements
Solderability requirements can be expressed in terms of the following parameters: 6.4.1 At the start of wetting, the time interval (t.-to). 6.4.2 During wetting, the actual wetting force at the specified time reaches a percentage of the theoretical wetting force or reference wetting force. 6.4.3 When wetting is stable, the actual wetting force at the end of the specified immersion cycle is expressed as a percentage of the maximum wetting force (wetting force at point C
wetting force at point B
×100%).
7 Details to be specified in the relevant standards
When the solderability test is specified to be carried out by the wet weighing method, the following details should be specified: a.
Whether cleaning is required;
Whether accelerated aging is required, if so, what method is used, whether active flux or inactive flux is used, the location of the test on the test sample, the depth of immersion:
The duration of immersion,
The parameters measured on the curve,
The acceptable value of the measured parameter.
GB2423.32-85
Appendix A
Requirements for test equipment
(Supplement)
A.1 The response time of the recording mechanism of the curve recorder shall meet the following requirements: At the maximum load displacement, it shall be able to return to the center zero point within 0.3s, and its overshoot shall not exceed 1% of the corresponding maximum load value. A.2 The instrument shall have several sensitivity grades. The most sensitive range is equivalent to the maximum deviation from the center position when 200 mg of mass is suspended in the test sample fixture. A.3 The drawing speed should be no less than 10 mm/s.
The electrical and mechanical noise equivalent of the recorder should not exceed 4·10-5 Np. A, 4 The deflection of the recording mechanism should be proportional to the measured force, and the accuracy should be better than 95% over the entire scale range. A.5 The stiffness of the spring system of the weighing mechanism should be such that the vertical displacement of the test sample produced under the action of a force of 5×10-3 N does not exceed 0.1 mmwwW.bzxz.Net
A, 6 The size of the soldering trough should be large enough so that any part of the test sample is no less than 15 mm away from the trough wall and the bottom of the trough. A.7 The temperature of the solder in the trough to be tested is 235±2℃. A.8 The immersion depth of the lowest point of the test sample should be adjustable to any position between 1 and 5 mm, with a maximum adjustment error of +0.2 mm.
A.9 The immersion and removal speed should be 20±5 mm/s. A.10 The dwell time at the maximum immersion depth should be adjustable within the range of 0 to 10 s. Additional Notes:
This standard was proposed by the National Technical Committee for Environmental Technology Standardization of Electrical and Electronic Products. This standard was drafted by the National Technical Committee for Environmental Technology Standardization of Electrical and Electronic Products Wetting Weighing Method Solderability Test National Standard Compilation Working Group.
The main drafters of this standard are Zhou Xincai. Wang Xiuqing, Lu Shiji, Pang Huaixin, Wang Xiping, He Chengshan, etc. 332
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