Workpiece Plating Treatment Method and Workpiece Manufacturing Method

Abstract

A workpiece plating treatment method includes the steps of cleaning an outer surface of an outer plating layer of a workpiece to remove a plurality of oxides and dirt on the outer surface of the outer plating layer, and reflow melting the outer plating layer of the workpiece using a reflow melting device after the cleaning.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of the filing date under 35 U.S.C. § 119(a)-(d) of Chinese Patent Application No. 202210570367.1, filed on May 24, 2022.

FIELD OF THE INVENTION

The present invention relates to a workpiece plating treatment method and a workpiece manufacturing method.

BACKGROUND

Although the electrical conductivity of low melting point metal plating such as tin, indium, bismuth, and lead plating is not as good as that of precious metals such as gold and platinum, they also rank among the top of most metals, especially tin plating, which is widely used in the welding and crimping of electronic connectors and their mating ends, such as PCB s, due to its low melting point, good ductility, and low price. With the rapid development of press fit technology, as well as the increasing demand for connector robustness in mobile applications such as automotive applications, press fit applications are increasingly replacing complex welding. However, in order to maintain sufficient crimping retention force (pull-out force) to prevent the connection from loosening due to vibration and maintain a sufficiently low contact resistance, the insertion force of crimping is too large, which can lead to two problems. The first problem is the difficulty of assembly and insertion, and excessive damage to the tin plating layer at both ends of the mating. The second problem is that insertion damage can exacerbate the growth of tin whiskers in the tin plating layer, which can lead to a short circuit between adjacent terminals or PCB lines.

In order to solve the above problems, reflow tin melting technology was applied. The principle is that the tin plating layer is cooled and recrystallized after melting, and an intermetallic compound is formed between the freely molten tin and the base layer or intermediate plating layer. The hardness increases, the wear resistance decreases, the surface roughness decreases, and the friction coefficient decreases. Under the same pressing force, the insertion force decreases (insertion force=friction coefficient*positive pressure). At the same time, the internal stress of the tin plating layer is released after remelting, further reducing the risk of tin whiskers. Currently, the common methods for reflow tin melting are to use electric furnace resistance wires to melt tin plating, infrared thermal radiation baking to melt tin plating, or inductive heating to melt tin plating.

However, in prior art, no matter which method is used to reflow melt tin plating, the problem of uneven melting of tin plating cannot be solved. There are two main reasons for this problem:

The first reason is that the tin plating workpiece before reflow melting can be oxidized and contaminated through multiple processes such as assembly. Even if the fresh tin plating just obtained from the electroplating production line is subjected to drying and other processes, the tin plating surface is more or less oxidized, and the melting point of tin oxide is as high as 1630° C., while the melting point of tin is only 232° C. Therefore, during the reflow melting tin plating process, the inclusion of tin oxide can cause uneven wetting and asynchronous melting, resulting in shrinkage, porous bulging, and other problems.

The second reason is that, during the reflow melting tin plating process, the molten tin interface reacts with oxygen in the air at high temperatures to generate tin oxide, which affects the contact resistance and friction coefficient during subsequent use. Although inert gases such as nitrogen or argon are commonly used in the industry for protection, many non-hermetic processes are not suitable for the extensive use of inert gases. At the same time, due to the limitations of product structure, different parts of the tin plating surface have different heat absorption rates, which can also lead to asynchronous melting, cooling, and recrystallization, and also lead to shrinkage, porous bulges, and other issues.

Of the above two reasons, the second reason is typically the focus, while the first reason is less commonly considered. However, the experimental results show that the harm of the first cause is far greater than that of the second cause. Even using precise laser melting cannot eliminate the adverse effects caused by the first cause. The industry often misjudges the defects caused by the first cause as improper settings of melting equipment and parameters such as temperature curves. Engineers have made significant improvements in equipment and operating parameters. However, the uneven and unstable melting of tin plating that has plagued the industry has not been solved.

SUMMARY

A workpiece plating treatment method includes the steps of cleaning an outer surface of an outer plating layer of a workpiece to remove a plurality of oxides and dirt on the outer surface of the outer plating layer, and reflow melting the outer plating layer of the workpiece using a reflow melting device after the cleaning.

BRIEF DESCRIPTION OF THE DRAWINGS

Features of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the accompanying drawings, in which:

FIG. 1 is a schematic side view of a workpiece according to an embodiment;

FIG. 2 is a schematic side view of water shrinking into water droplets on the outer surface of the outer plating layer of the workpiece before the outer surface of the outer plating layer is cleaned;

FIG. 3 is a schematic side view of evenly spreading water onto the outer surface of the outer plating layer of the workpiece to form a uniform water film after cleaning the outer surface of the outer plating layer;

FIG. 4 is a schematic side view of forming a protective film on the outer surface of the outer plating layer of the workpiece;

FIG. 5 is a schematic side view of a workpiece according to another embodiment; and

FIG. 6 is a schematic side view of forming a protective film on the outer surface of the outer plating layer of the workpiece shown in FIG. 5.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary embodiments of the present disclosure will be described hereinafter in detail with reference to the attached drawings, wherein like reference numerals refer to like elements. The present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure will convey the concept of the disclosure to those skilled in the art.

In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.

As shown in FIG. 1, in the illustrated embodiment, a workpiece 100 includes a substrate 10 and an outer plating layer 11 formed on the surface of the substrate 10. A method for processing the outer plating layer 11 of the workpiece 100 shown in FIG. 1 will be described below. In an exemplary embodiment of the present invention, the method comprises the following steps:

S100: cleaning an outer surface of the outer plating layer 11 of the workpiece 100 to remove oxides and dirt on the outer surface of the outer plating layer 11; and

S200: after step S100, the outer plating layer 11 of the workpiece 100 is reflow melted using a reflow melting device.

FIG. 2 is an illustrative view of water shrinking into water droplets 1 on the outer surface of the outer plating layer 11 of the workpiece 100 before the outer surface of the outer plating layer 11 is subjected to cleaning treatment. FIG. 3 is an illustrative view in which water is evenly spread onto the outer surface of the outer plating layer 11 of the workpiece 100 to form a uniform water film 2 after cleaning treatment.

As shown in FIGS. 2 and 3, in the illustrated embodiment, after cleaning the outer surface of the outer plating layer 11 of the workpiece 100, the moisture content of the outer surface of the outer plating layer 11 will be increased, so that water can be evenly spread on the surface of the workpiece 100. Similarly, when performing reflow melting treatment on the outer plating 11 of the workpiece 100 using a reflow melting device, the molten outer plating material will also uniformly flow and lay evenly on the surface of the workpiece 100, avoiding the problems of shrinkage, porosity, and bulging of the molten outer plating material, improving the uniformity and stability of the outer plating layer 11 during reflow melting. In the step S100, oxides and dirt on the outer surface of the outer plating layer 11 of the workpiece 100 can be removed using, for example, plasma, laser, flux, or any combination of the three to increase the moisture content of the outer surface of the outer plating layer 11.

In various embodiments, the reflow melting device used in the step S200 can include at least one of a resistance wire melting furnace, an infrared radiation melting furnace, an inductance melting furnace, and a laser melting furnace.

As shown in FIG. 1, in an exemplary embodiment of the present invention, the aforementioned workpiece plating treatment method further comprises a step of:

S300: After step S200, the outer surface of the outer plating layer 11 of the workpiece 100 is polished to flatten the outer surface of the outer plating layer 11.

In an exemplary embodiment of the present invention, in the step S300, for example, the workpiece 100 can be immersed in an optical polishing liquid to perform a chemical polishing treatment on the outer surface of the outer plating layer 11 of the workpiece 100. In another embodiment, in the step S300, for example, the outer surface of the outer plating layer 11 of the workpiece 100 can be physically polished using a physical polishing device. The physical polishing device may include a sandblasting polishing device, a cloth wheel polishing device, or a plasma polishing device. In the step S300, a physical chemical mixing polishing device can be used to perform a physical chemical mixing polishing treatment on the outer surface of the outer plating layer 11 of the workpiece 100.

FIG. 4 is an illustrative view of forming a protective film 12 on the outer surface of the outer plating layer 11 of the workpiece shown in FIG. 1. As shown in FIGS. 1 and 4, in the illustrated embodiment, the aforementioned workpiece plating treatment method also includes a step of:

S400: After step S300, a protective film 12 is formed on the outer surface of the outer plating layer 11 of the workpiece 100.

In the step S400, the protective film 12 may include at least one of a passivation protective film, a lubricating oil protective film, and a nano organic protective film. In the step S400, the outer surface of the outer plating layer 11 of the workpiece 100 can be passivated to form a passivation protective film on the outer surface of the outer plating layer 11. In the step S400, the outer surface of the outer plating layer 11 of the workpiece 100 can be lubricated to form a protective film of lubricating oil on the outer surface of the outer plating layer 11. In an embodiment, in the step S400, the outer surface of the outer plating layer 11 of the workpiece 100 can be sputtered to form a layer of nano organic protective film on the outer surface of the outer plating layer 11.

In an exemplary embodiment of the present invention, a workpiece manufacturing method is also disclosed, comprising the following steps:

S10: providing a workpiece 100 with an outer plating layer 11; and

S20: using the aforementioned workpiece plating treatment method to treat the outer plating layer 11 of the workpiece 100.

The aforementioned step S10 includes:

S11: providing substrate 10; and

S13: forming an outer plating layer 11 on the substrate 10.

In various embodiments, the outer plating layer 11 can be formed on the surface of the substrate 10 by an electroplating process or an electroless plating process.

FIG. 5 is an illustrative view of a workpiece 100 according to another exemplary embodiment of the present invention. FIG. 6 is an illustrative view of forming a protective film 12 on the outer surface of the outer plating layer 11 of the workpiece 100 shown in FIG. 5.

In the embodiment of FIGS. 5 and 6, the aforementioned step S10 further comprises a step of:

S12: Before step 13, at least one intermediate plating layer 13 is formed on the substrate 10.

In various embodiments, the substrate 10 of the workpiece 100 may be a copper substrate, a steel substrate, or other suitable conductive substrate. The aforementioned at least one intermediate layer 13 may include a nickel-plating layer and/or other suitable plating layer.

In various embodiments, the outer plating layer 11 on the workpiece 100 may be a tin plating layer, an indium plating layer, a bismuth plating layer, a lead plating layer, or other suitable metal or alloy plating layer.

It should be appreciated for those skilled in this art that the above embodiments are intended to be illustrative, and not restrictive. For example, many modifications may be made to the above embodiments by those skilled in this art, and various features described in different embodiments may be freely combined with each other without conflicting in configuration or principle.

Although several exemplary embodiments have been shown and described, it would be appreciated by those skilled in the art that various changes or modifications may be made in these embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined in the claims and their equivalents.

As used herein, an element recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property.

Claims

1. A workpiece plating treatment method, comprising the steps of:

cleaning an outer surface of an outer plating layer of a workpiece to remove a plurality of oxides and dirt on the outer surface of the outer plating layer; and

reflow melting the outer plating layer of the workpiece using a reflow melting device after the cleaning.

2. The workpiece plating treatment method according to claim 1, further comprising:

polishing the outer surface of the outer plating layer of the workpiece after the reflow melting to flatten the outer surface of the outer plating layer.

3. The workpiece plating treatment method according to claim 2, further comprising:

forming a protective film on the outer surface of the outer plating layer of the workpiece after the polishing.

4. The workpiece plating treatment method according to claim 1, wherein the cleaning step includes using plasma, laser, flux, or any combination of the three to remove the oxides and dirt on the outer surface of the outer plating layer of the workpiece.

5. The workpiece plating treatment method according to claim 1, wherein the cleaning step increases a moisture content of the outer surface of the outer plating layer.

6. The workpiece plating treatment method according to claim 2, wherein, in the polishing step, the workpiece is immersed in an optical polishing liquid to perform a chemical polishing treatment on the outer surface of the outer plating layer of the workpiece.

7. The workpiece plating treatment method according to claim 2, wherein, in the polishing step, the outer surface of the outer plating layer of the workpiece is physically polished using a physical polishing device.

8. The workpiece plating treatment method according to claim 7, wherein the physical polishing device includes a sandblasting polishing device, a cloth wheel polishing device, or a plasma polishing device.

9. The workpiece plating treatment method according to claim 2, wherein, in the polishing step, the outer surface of the outer plating layer of the workpiece is subjected to a physicochemical mixed polishing treatment.

10. The workpiece plating treatment method according to claim 3, wherein the protective film includes at least one of a passivation protective film, a lubricating oil protective film, and a nano organic protective film.

11. The workpiece plating treatment method according to claim 3, wherein in forming step, the outer surface of the outer plating layer of the workpiece is passivated to form a passivation protective film on the outer surface of the outer plating layer.

12. The workpiece plating treatment method according to claim 3, wherein, in the forming step, the outer surface of the outer plating layer of the workpiece is lubricated to form a layer of lubricating oil protective film on the outer surface of the outer plating layer.

13. The workpiece plating treatment method according to claim 3, wherein, in the forming step, the outer surface of the outer plating layer of the workpiece is sputtered to form a layer of nano organic protective film on the outer surface of the outer plating layer.

14. The workpiece plating treatment method according to claim 1, wherein the reflow melting device includes at least one of a resistance wire melting furnace, an infrared radiation melting furnace, an inductance melting furnace, and a laser melting furnace.

15. A workpiece manufacturing method, comprising steps of:

providing a workpiece having an outer plating layer; and

processing the outer plating layer of the workpiece using the workpiece plating treatment method according to claim 1.

16. The workpiece manufacturing method according to claim 15, wherein providing the workpiece includes providing a substrate and forming the outer plating layer on the substrate.

17. The workpiece manufacturing method according to claim 16, wherein providing the workpiece includes forming an intermediate plating layer on the substrate before forming the outer plating layer on the substrate.

18. The workpiece manufacturing method according to claim 17, wherein the substrate is a copper substrate or a steel substrate.

19. The workpiece manufacturing method according to claim 18, wherein the intermediate plating layer includes a nickel plating layer.

20. The workpiece manufacturing method according to claim 15, wherein the outer plating layer is a tin plating layer, an indium plating layer, a bismuth plating layer, or a lead plating layer.