Method for forming plating layer on welding surface

Abstract

The method for forming the plating layer on the welding surface comprises the steps that a plating piece is placed in a vacuum chamber to be subjected to ion etching, so that a preset etching depth is formed on the welding surface of the plating piece; the plated part is subjected to ultrasonic cleaning; forming a hafnium layer on the welding surface of the plated part by vapor deposition; and forming a gold-hafnium alloy layer on the hafnium layer simultaneously by vapor deposition within a period of time of depositing the hafnium layer. According to the method, the hardness and tensile strength can be remarkably improved while the conductivity is guaranteed, the plating layer forming method is simple and efficient, the production cost is greatly reduced, and the method is suitable for industrial application and popularization.

Description

Technical Field

[0001] The present invention relates to the field of coating, and particularly to a method for forming a coating on a welding surface. Background Art

[0002] In the field of chip manufacturing, chip pads or terminal parts need to be welded to make the components conduct. Currently, common welding surfaces are usually made of the metal material gold (Au). Gold is corrosion-resistant and oxidation-resistant. However, its disadvantages are that the material property is relatively soft, the welding is not firm, and the hardness and tensile strength are insufficient; at the same time, the price is high, resulting in high manufacturing costs.

[0003] Therefore, it is necessary to provide a method for forming a coating on a welding surface to overcome the above defects. Summary of the Invention

[0004] The purpose of the present invention is to provide an improved method for forming a coating on a welding surface. This method is simple and easy to implement, and can form a new type of metal and alloy coating on the surface to be welded, thereby improving the hardness and tensile strength, and at the same time reducing the manufacturing cost.

[0005] To achieve the above purpose, the method for forming a coating on a welding surface of the present invention includes the following steps:

[0006] Placing the workpiece to be plated in a vacuum chamber for ion etching to form a predetermined etching depth on the welding surface of the workpiece;

[0007] Performing ultrasonic cleaning on the workpiece to be plated;

[0008] Forming a hafnium layer on the welding surface of the workpiece by vapor deposition; and

[0009] During a period of depositing the hafnium layer, simultaneously forming a gold-hafnium alloy layer on the hafnium layer by vapor deposition.

[0010] Compared with the prior art, in the method of the present invention, first, the workpiece to be plated is ion-etched to form a rough surface with a predetermined etching depth, which is convenient for subsequent metal layer deposition; then, after ultrasonic cleaning, a hafnium layer is formed on the welding surface by vapor deposition. During a period of depositing the hafnium layer, simultaneously a gold-hafnium alloy layer is formed on the hafnium layer by vapor deposition. That is to say, a hafnium layer with a predetermined thickness is first formed on the welding surface, and then hafnium and aluminum are simultaneously deposited to form a gold-hafnium alloy layer. In this way, while ensuring the conductivity, the hardness and tensile strength can be significantly improved. For example, compared with the gold layer, the hardness of the coating of the present invention is as high as HB126, and the tensile strength is as high as 530 Mpa. Moreover, the coating formation method of the present invention is simple and efficient, greatly reducing the production cost and being suitable for industrial promotion and use.

[0011] As an embodiment, the ion etching includes a first radio frequency glow treatment and a second radio frequency glow treatment.

[0012] Preferably, the first radio frequency glow treatment includes: introducing argon and oxygen, controlling the air pressure in the vacuum chamber to be 0.5 - 1 Pa, and controlling the first radio frequency glow discharge time to be 50 - 100 seconds.

[0013] Preferably, the flow rate of the oxygen is 20 - 25 sccm, and the flow rate of the argon is 50 - 100 sccm.

[0014] As an embodiment, the second radio frequency glow treatment includes: adjusting the oxygen valve to reduce the oxygen flow rate introduced into the vacuum chamber, the oxygen flow rate being 10 - 15 sccm, controlling the air pressure in the vacuum chamber to be 0.5 - 0.8 Pa, and controlling the second radio frequency glow discharge time to be 20 - 40 seconds.

[0015] As an embodiment, the ultrasonic cleaning includes: using isopropyl alcohol cleaning solution, controlling the ultrasonic frequency to be 25 - 35 kHz, and the ultrasonic power to be 250 - 300 W / cm 2 .

[0016] As an embodiment, depositing the hafnium layer includes: providing a hafnium nitride target, introducing nitrogen into the vacuum chamber, controlling the air pressure in the vacuum chamber to be 1 - 1.5 Pa, controlling the bias voltage to be -200 V to -250 V, and depositing to form the hafnium layer.

[0017] Preferably, the deposition time of the hafnium layer is 15 - 20 minutes.

[0018] As an embodiment, depositing the gold - hafnium alloy layer includes: providing a gold target, maintaining the air pressure in the vacuum chamber to be 1 - 1.5 Pa, controlling the bias voltage to be -100 V to -150 V, and depositing to form the gold - hafnium alloy layer, wherein the deposition start time of the gold - hafnium alloy layer is later than that of the hafnium layer.

[0019] As an embodiment, the deposition time of the hafnium layer is 8 - 10 minutes. Detailed Embodiments

[0020] To make the above - mentioned objects, features, and advantages of the present application more obvious and understandable, the following describes the detailed embodiments of the present application in conjunction with some embodiments. Many specific details are set forth in the following description in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0021] In the description of the present application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present application, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0022] In the present application, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher level height than the second feature. The first feature being "under", "below" and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower level height than the second feature.

[0023] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation.

[0024] The following further describes the method for forming a coating on the welding surface of the present invention in conjunction with embodiments, but does not limit the present invention thereby. The method of the present invention aims to provide a method for forming a coating on the welding surface, which is simple and feasible, can form a new type of metal and alloy coating on the surface to be welded, thereby improving the hardness and tensile strength, and reducing the manufacturing cost at the same time.

[0025] In an embodiment of the method for forming a coating on the welding surface of the present invention, the following steps are included:

[0026] Placing the workpiece to be plated in a vacuum chamber for ion etching to form a predetermined etching depth on the welding surface of the workpiece;

[0027] Ultrasonic cleaning the workpiece to be plated;

[0028] Forming a hafnium layer on the welding surface of the workpiece by vapor deposition; and

[0029] During a period of depositing the hafnium layer, simultaneously forming a gold-hafnium alloy layer on the hafnium layer by vapor deposition.

[0030] In the method of the present invention, first, the workpiece to be plated is subjected to ion etching to form a rough surface with a predetermined etching depth, so as to facilitate the subsequent deposition of the metal layer; then, after ultrasonic cleaning, a hafnium layer is formed on the welding surface by vapor deposition. During a period of depositing the hafnium layer, a gold-hafnium alloy layer is simultaneously formed on the hafnium layer by vapor deposition. That is to say, a hafnium layer with a predetermined thickness is first formed on the welding surface, and then hafnium and aluminum are simultaneously deposited to form a gold-hafnium alloy layer. In this way, while ensuring the conductivity, the hardness and tensile strength can be significantly improved. For example, compared with the gold layer, the hardness of the coating of the present invention is as high as HB126, and the tensile strength is as high as 530 Mpa. Moreover, the coating formation method of the present invention is simple and efficient, greatly reducing the production cost and being suitable for industrial promotion and use.

[0031] Specifically, a rough surface is formed on the welding surface by ion etching, and the purpose is to make the subsequent deposition of the metal layer and the alloy layer easier and the connection of the layers more firm. The ion etching of the present invention includes a first radio frequency glow treatment and a second radio frequency glow treatment. By the method of radio frequency glow discharge, that is, a high-frequency high voltage is applied between the anode and cathode electrodes in the vacuum chamber, and glow discharge occurs between the anode and cathode electrodes, generating argon plasma and oxygen plasma. The two high-energy plasmas bombard the welding surface, causing the organic dirt at this position to fall off, oxidize, decompose, and form a rough pattern with a predetermined depth. To achieve the above purpose, the workpiece to be plated is placed in the vacuum chamber and first subjected to the first radio frequency glow treatment. Specifically, argon and oxygen are introduced. Preferably, the flow rate of oxygen is controlled at 20-25 sccm, and the flow rate of argon is controlled at 50-100 sccm to control the air pressure in the vacuum chamber at 0.5-1 Pa, and the first radio frequency glow discharge time is controlled at 50-100 seconds. Then, the second radio frequency glow treatment is carried out, including: adjusting the oxygen valve to reduce the flow rate of oxygen introduced into the vacuum chamber, the flow rate of oxygen is 10-15 sccm, controlling the air pressure in the vacuum chamber at 0.5-0.8 Pa, and controlling the second radio frequency glow discharge time at 20-40 seconds. After the radio frequency glow discharge treatment, the etching depth is preferably 20-30 nanometers.

[0032] Then, the workpiece to be plated is immersed in an ultrasonic cleaning solution for ultrasonic cleaning. Preferably, isopropyl alcohol (IPA) cleaning solution is used, the ultrasonic frequency is controlled at 25-35 kHz, and the ultrasonic power is 250-300 W / cm 2 , carried out at room temperature, and the immersion time is 10-20 minutes.

[0033] Next, vapor deposition is carried out. Specifically, a hafnium nitride target is prepared, and pure argon gas is introduced to keep the vacuum degree of the vacuum chamber at 1 - 1.5 Pa. At this time, the working voltage is a bias voltage of -200 V to -250 V, the temperature is 250 - 280 °C, the deposition time is 15 - 20 minutes, and the thickness of the formed hafnium layer is 12 - 15 nanometers. Then, the gold target is opened, and the vacuum degree of the vacuum chamber is continuously kept at 1 - 1.5 Pa. At this time, the working voltage acting on the gold target is a bias voltage of -100 V to -150 V. While depositing hafnium, gold is deposited, and the deposition time is 8 - 10 minutes to form a gold-hafnium alloy layer with a thickness of 5 - 8 nanometers. Specifically, the starting time of depositing gold is later than that of depositing hafnium, that is, after depositing a predetermined thickness of hafnium, gold is deposited, thereby forming a predetermined gold-hafnium alloy layer. Thus, the formation of the hafnium layer and the gold-hafnium alloy layer is completed.

[0034] Thus, the plating formation method for the welding surface of the present invention first forms a hafnium layer with a predetermined thickness on the welding surface, and then deposits hafnium and aluminum simultaneously to form a gold-hafnium alloy layer. In this way, while ensuring the conductivity, the hardness and tensile strength can be significantly improved. For example, compared with the gold layer, the hardness of the plating of the present invention is as high as HB126, and the tensile strength is as high as 530 Mpa. Moreover, the plating formation method of the present invention is simple and efficient, greatly reducing the production cost and being suitable for industrial promotion and use.

[0035] The above-disclosed are only the preferred embodiments of the present invention, and of course, the scope of the rights of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the scope of the patent application of the present invention still fall within the scope covered by the present invention.

Claims

1. A method for forming a coating on a welding surface, characterized in that, it includes the following steps: Placing the workpiece to be plated in a vacuum chamber for ion etching to form a predetermined etching depth on the welding surface of the workpiece; Ultrasonically cleaning the workpiece to be plated; Forming a hafnium layer on the welding surface of the workpiece by chemical vapor deposition; and During a period of depositing the hafnium layer, simultaneously forming a gold-hafnium alloy layer on the hafnium layer by chemical vapor deposition.

2. The method for forming a coating on a welding surface according to claim 1, characterized in that, The ion etching includes a first radio frequency glow treatment and a second radio frequency glow treatment.

3. The method for forming a coating on a welding surface according to claim 2, characterized in that, The first radio frequency glow treatment includes: introducing argon and oxygen, controlling the air pressure in the vacuum chamber to be 0.5 - 1 Pa, and controlling the first radio frequency glow discharge time to be 50 - 100 seconds.

4. The method for forming a coating on a welding surface according to claim 3, characterized in that, The flow rate of the oxygen is 20 - 25 sccm, and the flow rate of the argon is 50 - 100 sccm.

5. The method for forming a coating on a welding surface according to claim 3, characterized in that, The second radio frequency glow treatment includes: adjusting the oxygen valve to reduce the flow rate of oxygen introduced into the vacuum chamber, the flow rate of the oxygen being 10 - 15 sccm, controlling the air pressure in the vacuum chamber to be 0.5 - 0.8 Pa, and controlling the second radio frequency glow discharge time to be 20 - 40 seconds.

6. The method for forming a coating on a welding surface according to claim 1, characterized in that, The ultrasonic cleaning includes: using isopropyl alcohol cleaning solution, controlling the ultrasonic frequency to be 25 - 35 kHz, and the ultrasonic power to be 250 - 300 W / cm 2 .

7. The method for forming a coating on a welding surface according to claim 1, characterized in that, Depositing the hafnium layer includes: providing a hafnium nitride target, introducing nitrogen into the vacuum chamber, controlling the air pressure in the vacuum chamber to be 1 - 1.5 Pa, controlling the bias voltage to be -200 V to -250 V, and depositing to form the hafnium layer.

8. The method for forming a coating on a welding surface according to claim 7, characterized in that, The deposition time of the hafnium layer is 15 - 20 minutes.

9. The method for forming a coating on a welding surface according to claim 1, characterized in that, Depositing the gold-hafnium alloy layer includes: providing a gold target, maintaining the air pressure in the vacuum chamber to be 1 - 1.5 Pa, controlling the bias voltage to be -100 V to -150 V, and depositing to form the gold-hafnium alloy layer, wherein the deposition start time of the gold-hafnium alloy layer is later than the deposition start time of the hafnium layer.

10. The method for forming a coating on a welding surface according to claim 9, characterized in that, The deposition time of the hafnium layer is 8 - 10 minutes.