PIN applied to power module and manufacturing method

Abstract

The invention discloses a PIN applied to a power module and a manufacturing method, and relates to a power semiconductor packaging technology, the PIN comprises a pin body, the lower end of the pin body is provided with an inclined side surface, and the lower end of the pin body is in a positive frustum shape; the lining plate comprises a first layer plate, a positioning groove is formed in the first layer plate, and the shape of the positioning groove is matched with that of the lower end of the needle body and larger than that of the lower end of the needle body; a solder layer is arranged between the needle body and the positioning groove, and the needle body is fixed in the positioning groove through the solder layer. According to the pin, the lower end of the pin body is set to be in the shape of the regular circular truncated cone, so that the tin solder plated in advance reacts with the first layer plate made of copper and the pin body at high temperature to form the intermetallic compound, the intermetallic compound flows into the positioning groove along the side face, the welding area between the pin body and the positioning groove is increased, and therefore the mechanical strength is improved.

Description

Technical Field

[0001] This invention relates to power semiconductor packaging technology, and in particular to a PIN pin used in power modules and a method for manufacturing it. Background Technology

[0002] In power modules, some functional pin signal terminals (such as drive control, temperature sensors, current detection, etc.) generally need to be managed separately from power terminals, and are often connected using PIN pins. PIN pins are not only the current path between the internal chip and the external circuit board, but also the main mechanical connection point between the module and the external circuit, bearing the stress caused by PCB installation, connector plugging and unplugging, transportation vibration, etc.

[0003] like Figure 1 and Figure 2 The PIN connection shown involves soldering the PINs to the substrate using solder paste pre-applied to the substrate during reflow soldering. However, the shape of the existing PINs makes them prone to poor solder creep during reflow soldering, resulting in insufficient effective soldering area, weak mechanical strength of the PINs, and even the risk of cold solder joints. Furthermore, although the interface of the traditional reflow solder layer is an intermetallic compound, the presence of solder within the layer results in a low overall melting point, making the module unsuitable for high-temperature environments. Summary of the Invention

[0004] This invention provides a PIN pin for use in power modules and a method for manufacturing it, with the aim of solving the problem of insufficient solder strength between the PIN pin and the substrate.

[0005] To achieve the above objectives, embodiments of the present invention provide a PIN pin for a power module, comprising: The needle body has an inclined side at its lower end, and the lower end of the needle body is in the shape of a frustum conical. The liner includes a first layer plate, on which a positioning groove is provided. The shape of the positioning groove is adapted to the shape of the lower end of the needle body and is larger than the lower end of the needle body. A solder layer is provided between the needle body and the positioning groove, and the needle body is fixed in the positioning groove by the solder layer.

[0006] Preferably, the solder layer is .

[0007] Preferably, the liner further includes a second layer plate and a third layer plate disposed sequentially below the first layer plate, the second layer plate being fixedly connected to the first layer plate and the third layer plate respectively, and the first layer plate and the third layer plate being made of copper metal.

[0008] Preferably, the second layer is made of ceramic material.

[0009] Preferably, the needle body is made of copper.

[0010] This application also provides a method for manufacturing a PIN pin, used to manufacture the aforementioned PIN pin: S100. Plating or vapor deposition of tin solder on the lower end face and lower circumference of the needle body; S200. Install the needle body into the positioning groove; S300. The needle body and liner are subjected to nitrogen-based atmosphere protection heat treatment.

[0011] Preferably, in step S300, the heating temperature is 250°C and the duration is 30-40 minutes.

[0012] The above-described solution of the present invention has the following beneficial effects: In this application, by setting the lower end of the needle body to a frustum shape, the solder flows down along the side of the lower end of the needle body into the positioning groove when the needle body is heated and welded, thereby increasing the welding area between the needle body and the positioning groove and thus improving the mechanical strength.

[0013] Furthermore, tin and copper form [a specific reaction] under high temperature conditions. The intermetallic compound has a melting point much higher than the welding temperature, allowing the power module to operate at higher ambient temperatures.

[0014] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of existing PIN pins; Figure 2 yes Figure 1 Enlarged view of section A; Figure 3 The liner in this application, Figure 4 This is a schematic diagram of the needle body in this application; Figure 5 This is a schematic diagram of this application; Figure 6 yes Figure 5 Enlarged view of section B.

[0016] [Explanation of Labels in the Attached Images] 10-Needle body, 20-Backing plate, 21-First layer plate, 22-Second layer plate, 23-Third layer plate, 24-Positioning groove, 30 - Solder layer. Detailed Implementation

[0017] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0018] like Figures 3-6 As shown, an embodiment of the present invention provides a PIN pin for a power module, including a pin body 10 and a backing plate 20. The pin body 10 is elongated and has an upper end and a lower end. The upper end of the pin body 10 is cylindrical, and the lower end of the pin body 10 is frustum-shaped, meaning the diameter of the lower end of the pin body 10 gradually increases from top to bottom. The frustum-shaped lower end of the pin body 10 results in an inclined side surface. The aforementioned backing plate 20 includes a first backing plate 20, on which at least one positioning groove 24 is provided. The shape of the positioning groove 24 is adapted to the shape of the lower end of the pin body 10 and is larger than the lower end of the pin body 10, thereby allowing the lower end of the pin body 10 to be accommodated by the positioning groove 24.

[0019] A solder layer 30 is provided at the lower end of the needle body 10 between the needle body 10 and the positioning groove 24, which fixes the needle body 10 and the positioning groove 24 together.

[0020] In this application, solder layer 30 is .

[0021] The aforementioned liner 20 also includes a second layer plate 22 and a third layer plate 23, which are sequentially disposed below the first layer plate 21. The second layer plate 22 is fixedly connected to the upper first layer plate 21 and the lower third layer plate 23 respectively. The first layer plate 21 and the third layer plate 23 are made of copper, and the second layer plate 22 is made of ceramic, which can be aluminum nitride ceramic or silicon nitride ceramic.

[0022] The needle body 10 is made of copper.

[0023] This application also provides a method for manufacturing a PIN pin, comprising the following steps: S100: As Figure 4 Solder is plated or vapor-deposited onto the lower end face and lower circumference of the needle body 10, so that the lower end of the needle body 10 is uniformly covered with solder. S200. Install the needle body 10 with solder in the positioning groove 24, and adjust the position of the needle body 10 so that the center of the lower end of the needle body 10 coincides with the center of the positioning groove 24. S300. Perform nitrogen-based atmosphere-protected heat treatment on the needle body 10 and the liner plate 20 to complete the welding of the needle body 10 to the first layer plate 21.

[0024] In step S300, the needle body 10 and the liner 20 are placed in a nitrogen furnace and kept at 250°C for 30-40 minutes.

[0025] During soldering, an excess reaction occurs between tin and the copper-based needle body 10 and the first layer plate 21. The melting temperature of tin is 232°C, and the soldering temperature is maintained at 250°C for a sufficient time until no tin remains, finally forming the solder layer. The intermetallic compound enables a permanent connection between the needle body 10 and the liner 20.

[0026] The lower end of the needle body 10 is a perfect circular platform. During the welding process, molten solder flows into the positioning groove 24 and reacts with the copper first layer plate 21 to generate Cu-Sn intermetallic compounds, which further strengthens the connection between the needle body 10 and the first layer plate 21.

[0027] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A PIN pin for use in a power module, characterized in that, include: The needle body (10) has an inclined side at its lower end, and the lower end of the needle body (10) is in the shape of a frustum conical. The liner (20) includes a first layer plate (21), on which a positioning groove (24) is provided. The shape of the positioning groove (24) is adapted to the shape of the lower end of the needle body (10) and is larger than the lower end of the needle body (10). The needle body (10) and the positioning groove (24) are connected by a solder layer (30) at the lower end of the needle body (10), and the needle body (10) is fixed in the positioning groove (24) by the solder layer (30).

2. The PIN pin for a power module according to claim 1, characterized in that: The solder layer (30) is .

3. The PIN pin for a power module according to claim 3, characterized in that: The liner (20) also includes a second layer plate (22) and a third layer plate (23) arranged sequentially below the first layer plate (21). The second layer plate (22) is fixedly connected to the first layer plate (21) and the third layer plate (23) respectively. The first layer plate (21) and the third layer plate (23) are made of copper metal.

4. The PIN pin for a power module according to claim 3, characterized in that: The second layer (22) is made of ceramic.

5. The PIN pin for a power module according to claim 2, characterized in that: The needle body (10) is made of copper.

6. A method for manufacturing a PIN pin, used to manufacture the PIN pin according to any one of claims 2-5, characterized in that: S100. Plating or vapor deposition of tin solder on the lower end face and lower circumferential direction of the needle body (10); S200. Install the needle body (10) into the positioning groove (24); S300. The needle body (10) and the liner (20) are subjected to nitrogen-based atmosphere protection heat treatment.

7. The method for manufacturing a PIN pin according to claim 6, characterized in that: In step S300, the heating temperature is 250°C and the duration is 30-40 minutes.

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