1 Range
This STANDARD specifies the technical REQUIREMENTS AND test methods for electroplating of Tin-lead alloys with tin content ranging from 50% to 70%(mass ratio) (see 10.3).

This standard applies to electroplating of tin-lead alloys to prevent corrosion and improve soldering properties on electronic, electrical and other metal products.

This standard also applies to tin-lead alloy coatings of other compositions, but it should be noted that the properties of these coatings may differ from those of tin-lead alloy coatings of the above alloy composition range.

The classification method in this standard clearly indicates the class of the base metal and the composition of the coating within a certain tin content range, as well as the provisions for hot melt and bright deposition layers.

ISO 7587-1986 Metal cover Tin-aluminum alloy electroplating

This Standard does not apply to:

a) tin-lead alloy coating on threaded parts;

b) tin-lead alloy coating on bearings;

) tin-lead alloy coating on unworked forms of sheet, strip or wire or on parts formed from them;

d) Tin-lead alloy coating on steel with tensile strength greater than 1000Mpa(or corresponding hardness), because such steel is prone to hydrogen embrittleness after electroplating (see 8.2).

2 Reference Standards
The FOLLOWING standards CONTAIN provisions which, by reference in this standard, constitute provisions of this standard. All versions shown are valid at the time of publication of this standard. All standards are subject to revision and parties using this standard should explore the possibility of using new versions of the following standards.

Basic environmental test code for electronic and electrical products Test T: solder welding test method (eqv]EC68-2-20:1979)

Metal coating coating thickness measurement anodic dissolution Coulomb method (IDTIS 02177:1985)

Test method for Adhesion strength of metallic coatings (electrodeposited and chemically deposited) on metallic substrates (eqvIS02819:1980)

ISO 7587-1986 Metal cover Tin-aluminum alloy electroplating

Light industrial products — Test method for thickness of metal coatings and chemically treated coatings — beta ray backscattering method (IDTIS 03543:1981)

Method for microscopic measurement of cross-sectional thickness of metal and oxide coverings

Metal and other non-organic coverings — Sulfur dioxide corrosion test under normal condensation conditions (eqvIS06988:1985)

Corrosion test in artificial atmosphere Salt spray test (eqvIS09227:1990)

Chemical analysis of tin-lead solder – Determination of tin content by iodate method

ISO 7587-1986 Metal cover Tin-aluminum alloy electroplating

Metal and other inorganic coverings – Definitions and general rules for thickness measurement (eqvIS020 “:1990)

Procedures for sampling inspection of electrodeposited metal covers and related finishing counts (eqvIs04519:1980)

Metal cover thickness measurement-X-ray spectrometric method (eqvIS03497:1990)

ISO 7587-1986 Metal cover Tin-aluminum alloy electroplating

3 Definitions
The following definitions are used in this standard.

3.1 The main surface

Some SURFACE OF THE WORKPIECE THAT HAS BEEN PLATED OR IS TO BE PLATED, ON WHICH THE COATING IS IMPORTANT TO THE APPEARANCE AND/OR PERFORMANCE OF THE WORKPIECE, AND ALL REQUIREMENTS SPECIFIED IN THE STANDARD SHALL BE SATISFIED.

3.2 Basic measurement surface refe initial ncearea

An area on a major surface in which a specified number of single measurements are required.

3.3 Hot melt fl0w-melting

A PROCESS USED TO IMPROVE surface QUALITY TO obtain DESIRED PROPERTIES such as brightness or SOLdABILITY by means of a molten coating method (see D4 in Appendix D).

The MATERIALS THAT THE DEMANDER SHALL PROVIDE TO THE ELECTROPLATING MANUFACTURER
ISO 7587-1986 Metal cover Tin-aluminum alloy electroplating

4.1 Necessary Information

The Demander shall provide the following information to the electroplating manufacturer:

a) No. Of this national standard;

b) properties of the base metal (see Chapter 5);

c) Use condition number (see 7.1) or coating classification number (see 7.2) and alloy composition requirements (see 10.3); d) Whether the composition of the coating should be tested (see 10.3);

d) specify the main surface of the workpiece to be plated, such as marked with drawings or provided with suitably marked samples;

f) Sampling and inspection requirements (see Chapter 6);

g) Unavoidable corner traces and other acceptable coating defects on the workpiece (see 10.1);

h) The bonding strength test method adopted (see 10.4);

i) Special post-plating treatment (see D3.1 in Appendix D).

ISO 7587-1986 Metal cover Tin-aluminum alloy electroplating

4.2 Supplementary Information

The demander may also request the following supplementary information:

a) requirements for heat treatment (see Chapter 8);

b) Porosity test requirements (see 10.5);

Brazing test requirements and test methods and conditions of use (see 10.6);

d) Special requirements for the bottom coating (see Chapter 9);

Samples that can indicate the appearance requirements of the coating (see 10.l);

f) special pre-processing requirements;

g) Special packing requirements for self-plated parts.

Note: The Demander shall present the contents STIPULATED in 4.1 and, if necessary, the contents stipulated in 4.2. It is not sufficient to present the number of this standard without these contents.

ISO 7587-1986 Metal cover Tin-aluminum alloy electroplating

5 Matrix
This standard does not require the surface condition, appearance or surface roughness of the substrate before plating (see D2.1 in Appendix D). But because the substrate surface quality is too poor to make the coating can not meet the appearance and (or) performance requirements, can not be considered plating production quality does not meet the requirements.

6 Sample shot
When it is necessary to check whether the tin-lead coating meets the requirements specified in Chapter 10 of this standard, sampling shall be carried out according to the sampling method specified in GB/T12,609, and the acceptance level shall be agreed between the supplier and the demander.

7 Classification
7.1.Use condition numbers

According to the following conditions of the use of the environment, and the use of the condition number indicates the severity of the use condition:

4 especially harsh as the harsh corrosive conditions used outdoors (see D1 in Appendix D);

3 as harsh as typical outdoor temperature conditions;

2 Medium as used in indoor slightly condensed conditions;

Slightly as used in indoor dry atmosphere conditions, in this environment welding performance is the main requirement. note

1 See 10.2, where guidelines for the relationship between condition numbers and minimum thickness are given.

2 When the use of condition number or according to the layer classification number, attention should be paid to the tin-lead alloy in the abrasive or in some organic volatile steam ring

Damage is easy in the environment (see Appendix D).

ISO 7587-1986 Metal cover Tin-aluminum alloy electroplating

7.2 Coating classification number

The coating grade number consists of four parts, where the first two parts are separated by a short slash. Such as fbcd

Where :a represents the chemical symbol of the matrix metal (or the main component in the alloy matrix);

b I indicates the chemical symbol of the bottom coating metal (or the main component in the alloy bottom coating), and then the minimum thickness of the bottom coating is represented by a number in µm. If there is no bottom coating, it can be omitted (see 4.2d)).

One represents the composition of the coating, and the method is the chemical symbol sn and the mass percentage of tin in the coating, followed by a short horizontal line and the chemical symbol pb, and then the minimum thickness of the tin-lead coating, in µm;

d 1 represents the finishing state of the coating surface, symbol m is the matte coating,b is the bright coating, and f is the hot melt coating.

For example :Fe/Ni5Sn60-Pb10f This classification number indicates that the base metal is iron and steel, the bottom coating is nickel coating at least 5µm thick, and the nominal tin content of the tin-lead coating is 60%(mass ratio), at least 10µm thick, and is hot melt treated.

ISO 7587-1986 Metal cover Tin-aluminum alloy electroplating

Heat treatment of steel
8.1 Stress relief before plating

The deep cold deformation work hardening steel parts should be heat treated at a temperature of 190~220℃ for 1h before electroplating. To relieve stress.

After carburizing, flame quenching or high-frequency induction quenching and subsequent grinding of some steel, with the above conditions will damage its performance, can be replaced by a lower temperature to eliminate stress, such as 130~150℃, the processing time is not less than 5h.

8.2 Eliminate hydrogen embrittance after plating

Because the diffusion of hydrogen through the tin-lead coating is very slow, and the coating will melt at the temperature required by the hydrogen removal treatment, the heat treatment to eliminate hydrogen emittance is not required after electroplating.

Requirements for the bottom coating
For any of the following reasons, it is necessary to electrocoat some substrate materials:

a) prevention of proliferation (see D2.2 and D2.3 in Appendix D);

b) Maintain welding performance (see D2.2, D2.3 and D2.4 in Appendix D);

c) Ensure bond strength (see D2.4 and D2.5 in Appendix D);

d) improve and f erosion.

The choice of the bottom coating or the bottom coating system should be noted that it should not bring adverse properties, such as hydrogen embrittance of the base material or the plated parts, and the use of high stress nickel should be avoided.

ISO 7587-1986 Metal cover Tin-aluminum alloy electroplating

If the base material is a zinc-containing copper alloy and welding properties are required, in addition to the specified tin-lead alloy coating thickness (see 10.2), a nickel or copper substrate with a minimum local thickness of 2.5µm is required to maintain good appearance and bond strength (see D2.3 in Appendix D).

If an undercoat is specified, its performance (see Appendix D) and minimum local thickness (see 10.2) shall be specified by the Demander.

The thickness of a single substrate or multiple substrates shall be measured using the appropriate method specified in Appendix B(Standard Appendix).

ISO 7587-1986 Metal cover Tin-aluminum alloy electroplating

10 Requirements for coating
10.1 Appearance

During visual inspection, there should be no visible defects on the main surface of the plated part, such as blistering, pinholes, roughness, cracks or partial no coating, and no stains or discoloration.

The Demander shall specify acceptable and unavoidable marks on the joints and allowable defects on non-primary surfaces.

After plating, the surface of the workpiece should be clean, no damage, uniform, no nodules, and there should be no non-hole wet area at the melting place. The reticulate pattern that may appear on the surface cannot be regarded as unqualified.

If necessary, the demander shall provide or approve samples that show the appearance requirements of the coating.

10.2 Thickness

Classify tin-lead coatings by thickness and specify in Table 1 the minimum thickness value for each condition number (see 7.1) (see D3.2 in Appendix D).

ISO 7587-1986 Metal cover Tin-aluminum alloy electroplating

Thickness of coating

Within the basic measurement plane on the main surface, the thickness of any part that can be angled out by a 20mm diameter ball is measured using the appropriate method given in Appendix B. The minimum thickness of the coating shall meet the requirements specified in Table 1. In the case of the main surface area of the workpiece equal to or greater than 100mm2, the minimum thickness in the table should be regarded as the local thickness minimum. In the case of the main surface area of the workpiece is less than 100mm2, the minimum thickness in the table should be regarded as the average thickness minimum.

For printed circuit boards with plated vias, the minimum coating thickness requirement applies not only to any position on the main surface that can be reached by a 20mm diameter ball Angle, but also to the surface inside the vias (see Appendix B, B0.2.6).

The thickness requirements for hot melt coatings apply only to coatings in the pre-hot melt state (see D3.2,D4 and Appendix B in Appendix D).

When the thickness measurement is in dispute, the arbitration method specified in B0.2 in Appendix B shall be used.

ISO 7587-1986 Metal cover Tin-aluminum alloy electroplating

10.3 Ingredients

This standard is based on coatings with tin content ranging from 50% to 70%(mass ratio).

The nominal tin content should be indicated in the classification number and the composition tolerance should also be indicated in the information provided to the plating party (see note).

The analysis method for tin-lead coatings is given in Appendix A(STANDARD Appendix) and should be used in cases of dispute.

Note: Appendix D gives guidelines for the application of other constituent alloys.

10.4 Bond strength

If the Demander specifies testing for bonding strength, the coating shall be tested by one of the methods described in Appendix c(Standard Appendix) and shall not show signs of detachment from the substrate.

ISO 7587-1986 Metal cover Tin-aluminum alloy electroplating

10.5 Porosity

If the Demander provides for porosity measurement, the coatings with a minimum thickness of 10µm or greater shall be subjected to one of the following tests, with a number of test cycles to be agreed upon by the demander:

a) The iron matrix was tested according to GB/T10125;

b) Non-iron matrix was tested according to GB/T9789.

In both cases, there should be no evidence of substrate corrosion when the coating after the test is viewed with a 3x magnification (see D1 in Appendix D).

10.6 Welding performance (see D2 in Appendix D)

10.6.1 General materials and Parts

ISO 7587-1986 Metal cover Tin-aluminum alloy electroplating

If the Demander specifies testing of welding properties, the welding properties shall be tested with inactive flux according to Method 1 of Ta test in GB/T2423.28-1982.

If there is a requirement to accelerate aging before test, the aging procedure shall be specified by the demander.

10.6.2 Printed circuit boards

If the Demander specifies weldability testing, the printed circuit board coatings conforming to this standard shall be tested for weldability according to the Tc test in GB/T2423.28-1982.

If there is a requirement to accelerate aging before test, the aging procedure shall be specified by the demander.