This standard specifies the technical requirements and test methods for tin electroplating. This standard applies to tin electroplating on metal products for corrosion protection and soldering promotion. GB/T 12599-1990 Tin electroplating on metal coverings GB/T12599-1990 Standard download decompression password: www.bzxz.net
This standard specifies the technical requirements and test methods for tin electroplating. This standard applies to tin electroplating on metal products for corrosion protection and soldering promotion.

National Standard of the People's Republic of China
Metallic coatings
Flectroplated cnatingg of tin This standard is equivalent to the international standard [502093-198G "Specifications and test methods for electroplated coatings" 1 Subject content and applicable scope
This standard specifies the technical requirements and test methods for electroplated tin coatings. This standard is applicable to electroplated tin coatings on metal products for corrosion protection and welding promotion. This standard does not apply to:
Coatings on threads and spring parts;
Tin coatings on copper wires;
GB12599-90
Tin coatings on unprocessed sheets, strips or wires, or on products made from them; d.
Tin bonding layers on tin coatings obtained by chemical methods (diffusion, or chemical plating) with a tensile strength greater than 1 050 MPa (or corresponding hardness). 2 Reference standards
GB2423.28 Basic environmental test procedures for electronic products Test T: Soldering test method siB4955
GB 4956
GB 5270
GB G45
GB 6162
B 9789
Metal coating thickness determination Anodic coulomb method Measurement of thickness of non-magnetic coating on magnetic substrate Magnetic method Test method for adhesion strength of metal coating (electrodeposited layer and chemically deposited layer) on metal substrate Neutral salt test (NSS test) for metal coating Cross-sectional thickness measurement of metal and oxide coatings under microscope Test for sulfur monoxide corrosion of metal lips and other non-organic coatings under normal condensation conditions GE 12609
3 Terminology
3.1 Major Surfaces
Sampling Inspection Procedure for Counting of Electrodeposited Metal Coatings and Related Finishes Certain surfaces on a workpiece that have been prepared for electroplating: the coating on this surface is important enough to the appearance and/or performance of the workpiece. 3.2 Minimum Thickness
The minimum local thickness measured on the major surface of a workpiece. 3.3 Melt Flow
Is a process that uses melting method to eliminate coating defects and improve coating brightness and weldability. 4 Information that the purchaser should provide to the supplier
4.1 Necessary information
Approved by the State Administration of Technical Supervision on October 18, 1990 and implemented on December 1, 1991
The standard number of this standard, i.e. GB12599;
Properties of base materials (see Chapter 6);
GB12599-90
Coating service conditions and coating classification (see Chapter 5); Indicate the main surface of the workpiece to be plated, which can be indicated on the drawing or provided with samples with appropriate markings; Acceptance sampling method (see Chapter [0]);
Location of unavoidable contact marks and other permissible defects (see Article 9.1); Adopted bonding strength test piece method (see Article 9.3). 4.2 Supplementary information
If necessary, the following information shall also be provided: a.
Heat treatment requirements (see Chapter 7);
Porosity requirements (see Article 4);
Weldability requirements (see Article 9.5);
Base coating requirements (see Article 8);
Appearance requirements or provide samples indicating appearance requirements (see Article 9.3); Pretreatment requirements;
Tin coating purity requirements;
||Any other special requirements,
5 Classification
Use conditions classification
Use conditions are divided into four categories according to the severity of the use environment conditions: 1-Use for welding and dry indoor conditions: 2-Use for humid indoor conditions;
3: Use for general outdoor conditions:
-Use for outdoor harsh corrosion conditions, contact with food and beverages, under this condition, the tin coating must be fully covered to make the parts not easy to corrode and wear.
5.2 Coating classification
Coating classification consists of four parts, of which the first two parts must be separated by a slash: 8/bed, where:
a Mark the chemical symbol of the base metal (if it is a metal alloy, mark its main component) h-Mark the chemical symbol of the bottom coating metal (if it is an alloy, mark its main component): Mark the minimum thickness (um) value of the bottom coating. Especially the bottom coating, it can be omitted; indicate the chemical symbol Sn of the tin coating, and then indicate the minimum coating thickness (μm); d indicates the surface glossiness. m indicates matte coating; b indicates bright coating; f indicates melt-flow coating. s Example: Fe/Ni2. 5 Sn 5f
Here, it means steel or iron as the base metal, the bottom layer is 2.5um thick nickel-plated, and the tin coating is 5um thick. And it is melt-flow plated. 5.3 The corresponding relationship between the use conditions of the coating, the coating classification and the minimum coating thickness is listed in the following table. Use conditions
Copper base metal
Note, the bottom coating shall be carried out in accordance with the provisions of Chapter 8.
6 Base metal
GB12599—-90
Minimum thickness
Layer classification
Other base metals
Minimum thickness
This standard does not specify the surface condition of the substrate before electroplating, but the supplier and the buyer should reach an agreement on the surface condition of the substrate. Stress relief before electroplating of steel parts
Parts that have been cold-treated by electroplating need to be treated at 190-220℃ for 1h. Some steel parts that have been carburized, flame-extinguished or induction-treated, and ground need to be treated at 130-150℃ for more than 5h. 8 Requirements for bottom layer
Due to any of the following reasons, some base metals may require a bottom layer to prevent diffusion, maintain welding performance; ensure bonding strength; and improve anti-corrosion performance.
8. The bottom layer should not make the plated parts brittle, and try to avoid using stress-resistant nickel. 8.2 Bottom layer The minimum thickness of the coating and other requirements shall be specified by the product standard or the purchaser: If it is a zinc-free copper alloy substrate and there are requirements for welding performance, in addition to the specified tin coating thickness, a nickel or copper base coating with a minimum thickness of 2.5um is also required. 8.3 The base coating thickness is measured using the method specified in Appendix A (supplement). 9 Requirements and test methods for tin coating
9.1 Appearance
The plated parts must be clean and free of scratches. The surface is smooth and free of nodules. There shall be no anti-wetting surfaces in the molten zone. Visible defects such as blistering, pitting, cracks, local lack of coating, rust or discoloration, etc. are not allowed on the main surface. Inevitable traces of clamping The location of the tin plating layer and certain defects on the main surface of the card should be specified by the purchaser. If necessary, the purchaser may provide samples that can demonstrate the appearance requirements. 9.2 Thickness
9.2.1 The minimum thickness of the tin plating layer shall meet the requirements in the table of Article 5.3. When the main surface area is equal to or greater than 100mm, the thickness in the table is the minimum value of the local thickness. When the main surface area is less than 100mm, the thickness in the table is the minimum value of the average thickness of the plating layer. 9.2.2 When the chain component is a printed circuit board with plated through holes, the thickness requirements apply not only to the surface that can be contacted by a small ball with a diameter of 20mm, but also to the surface of the through hole. 9.2,3 When it is a melt flow coating, the thickness requirement is applicable to the electroplating state before melt flow. 9.2.4 Thickness measurement shall be carried out according to the method specified in Appendix A: 9.3 Bonding strength
Test according to one of the methods for measuring the bonding strength of tin electroplating layer specified in Table 2 of 6B5270. After the test, the coating should not peel off.
9.4 Porosity
GB1259990
If the purchaser has porosity requirements, for coatings with a thickness of not less than 1 (μm, the porosity of the coating can be assessed by one of the following tests: 9.4.1 Coatings on steel substrates shall be in accordance with G6158. 9. 4.2 For coatings on non-steel substrates, the coatings shall comply with the provisions of GB 9789. 9.4.3 After the test in accordance with 9.4.1 or 9.1.2, no substrate corrosion shall occur on the surface of the plated parts. 9.5 Welding performance
9.5.1 General materials and parts
If the purchaser requires, the welding performance test shall be carried out in accordance with the Ta test method in GB2423.28. If accelerated aging is required before the test, the aging process must be specified by the purchaser. 9.5.2 Printed circuit boards
If the purchaser requires the coating of printed circuit boards E that conform to this standard, the welding test may be carried out in accordance with the Fc test in GB 2423.28. If accelerated aging is required before the test, the aging process must be specified by the purchaser. 10 Sampling
Sampling inspection of tin plating shall be carried out according to the requirements of Article 9. The sampling method shall be carried out in accordance with the provisions of GB12609: A1 Determination of thickness
GE 12599—90
Appendix A\
Determination of coating thickness
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A1.1 When the coating thickness is greater than 10 μm, measure the thickness of the bottom coating and the tin coating according to the provisions of GB6462 microscope thickness measurement method. When measuring the thickness of the tin layer of the plated through hole of the printed circuit board, the microscopic section must be parallel to the axis of the hole and perpendicular to the surface of the coating or bottom layer to be measured. A1.2 Measure the thickness of the bottom coating and the tin coating according to the provisions of GB4955 coulometric thickness measurement method. A1.32) For tin coating without bottom coating on the iron substrate, it can be measured according to the magnetic method of GB 4956. A2 Determination of average thickness
A2.1 Principle
Use a suitable chemical solution to dissolve the tin on the sample, weigh the mass of the sample before and after dissolution by weighing, and calculate the average thickness of the coating on the sample based on the mass, density and area of ​​the tin. A2.2 Test solution and test conditions
The test solution is prepared with distilled water from analytical grade reagents. A2.2.1 Add 20 g of tantalum dioxide to 1000 mL of concentrated hydrochloric acid (p = 1.16 ~ 1.19 g/mL) and remove the tungsten coating on the iron substrate and the nickel base coating at room temperature.
A2.2.2 Remove the tin coating on the alloy in hydrochloric acid (p = 1.16 ~ 1.19 g/mL) above 90 °C. A2.3 Samples
One or more samples can be used, and the total area should provide a mass loss of not less than 0.1. The dirt on the surface of the sample should be cleaned with a suitable solvent.
A2. 4 Test process
Weigh the cleaned sample (accurate to 0.001 g) and immerse it in the stripping solution (A2.2.1, A2.2.2). When the coating is completely stripped, take out the test piece (after stripping with the A2.2.1 solution, wait for 2 minutes before taking it out), clean it in running water, and weigh it after drying (accurate to 0.001 g).
A2.5 Expression of test results
The results calculated using the following formula are expressed as the average coating thickness of the sample, = (m = m22 × 137 × 10%
Where: h
137X103
Instructions for use:
Average coating thickness, um:
Test mass before stripping.8;
Sample mass after stripping:
Sample surface area, mm\;
Calculation coefficient (calculated based on the density of tin: 7.3 area/cm).+(A1)
1] Appendix A of TSO 2093 specifies the use of ISO 8497 X-ray spectrometry thickness measurement method and IS0 3543 Thickness measurement by radiometric method. As the corresponding national standards have not been formulated in China, this standard does not adopt these two methods. 21502093 does not specify the use of magnetic thickness measurement method. This standard adds GE4056 magnetic thickness measurement method. A2.6 Arbitration method
GB1259990
When a dispute arises, the thickness measurement method under microscope of GB6462 shall be used for determination. Additional notes:
This standard was proposed and coordinated by the National Technical Committee for Standardization of Metal and Non-metallic Coatings. This standard was drafted by the Guangzhou Electrical Science Research Institute of the Ministry of Machinery and Electronics Industry. The seven main drafters of this standard are Luo Qingying, Chen Qizhi, Jiang Guozhao and Li Yingming
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