Preparation method of Ni3Sn4 / foamed nickel composite joint for high-temperature packaging

Abstract

The invention relates to a preparation method of a Ni3Sn4 / foamed nickel composite joint for high-temperature packaging. The method is characterized in that foamed nickel serves as a framework, a pure tin block serves as a filling material, a composite solder piece is manufactured according to a certain proportion, reliable connection is formed between electronic components such as an IGBT and a substrate through welding, and the micro welding spot formed by compositing IMC generated in situ and foamed nickel left after reaction is rapidly obtained. Compared with a traditional Ni / Sn / Ni structure TLP micro welding spot, the preparation time of the generated composite joint is shortened, and the composite joint has more excellent high-temperature resistance and good conductivity, meets current market requirements and can be widely applied to packaging of third-generation semiconductor power devices.

Description

Technical Field

[0001] The invention relates to packaging interconnection of third-generation semiconductor power devices, and in particular to a method for preparing a Ni3Sn4 / foam nickel composite joint for high-temperature packaging. Background Art

[0002] In recent years, with the emergence of new markets such as 5G communications, big data centers, and new energy vehicles, the performance of third-generation semiconductor power devices (especially high-temperature resistance) can no longer fully meet the demand. Therefore, it is urgent to develop high-performance semiconductor power devices with independent intellectual property rights, which is of great significance to promote the development of the Internet of Things, information industry, and intelligent industry. The stability of interconnection solder joints has attracted much attention in the packaging of third-generation semiconductor devices. In order to adapt to the high-temperature service environment of chips and follow the development trend of lead-free electronic packaging materials, it is urgent to develop high-performance and high-melting-point interconnection solder joints. At present, the methods used for packaging interconnection mainly include high-temperature lead-free solder, nanoparticle sintering, and transient liquid phase connection technology (Transient Liquid Phase, TLP). Among high-temperature lead-free solders, there are mainly Au-based solders, Zn-based solders and other systems. Among them, the processing cost of Au-based solders is high, and the processing temperature of Zn-based solders is high, which is easy to damage the chip. Although nanoparticle sintering can achieve the needs of "low-temperature connection and high-temperature service" for power device interconnection, its cost is high and the manufacturing process is complex, and the electromigration problem is the core problem that this method needs to solve. Transient liquid phase joining technology forms a high melting point joining layer through metallurgical reaction and is considered to be a promising bonding method for high temperature applications due to its flexibility in processing temperature.

[0003] At present, the TLP technology used for packaging interconnection studies the IMC joints of Ni-Sn system materials. At 300 °C, only one compound product Ni3Sn4 is generated, of which Ni3Sn4 has a melting point of 794.5 °C, an elastic modulus of 142 GPa, and Young's modulus and hardness values ​​ranging from 119 to 143 GPa and 6.0 to 7.0 GPa, respectively. Therefore, the full Ni3Sn4 compound joint can meet the needs of high-temperature chip connection. However, due to the low dissolution rate of Ni and the slow growth of Ni3Sn4, the bonding time required to form a compound joint composed entirely of Ni3Sn4 is relatively long, which limits its application in the packaging interconnection of third-generation semiconductor power devices.

[0004] The present invention uses nickel foam as a skeleton and pure tin block as a filling material to make a composite solder sheet in a certain proportion, and through the action of an external energy field, quickly obtains a micro solder joint composed of Ni3Sn4 generated in situ and the nickel foam remaining after the reaction. Compared with the traditional Ni / Sn / Ni structure TLP micro solder joint, its preparation time is shortened, and the obtained micro solder joint has more excellent high temperature resistance and good electrical conductivity. Summary of the invention

[0005] The present invention aims to prepare a full IMC micro solder joint with a high melting point and high reliability, solve the problem of poor high temperature reliability when the full IMC is used to connect the chip and the substrate in the third-generation semiconductor power device, and designs a Ni3Sn4 / nickel foam composite joint for high temperature packaging. The obtained joint has excellent high temperature resistance and good electrical conductivity, which meets the requirements of large-scale production and can be widely used in the connection of current high-temperature chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a schematic diagram of composite welding piece welding.

[0007] Figure 2 This is the SEM microstructure diagram of the micro solder joint after welding.

[0008] Figure 3 This is the EDX spectrum analysis diagram of the micro solder joint after welding.

Claims

1. A method for preparing a Ni3Sn4 / nickel foam composite joint for high temperature packaging, characterized in that: The steps include: (a) Cleaning of nickel foam, nickel substrate and pure tin block: The nickel foam, nickel substrate (5×5×0.1 mm) and pure tin block were respectively placed in an acetone solution for ultrasonic cleaning for 5 min to remove surface oil stains; then the nickel foam, nickel substrate and pure tin block were respectively placed in a 0.5% hydrochloric acid alcohol solution for ultrasonic cleaning for 5 min to remove surface oxides; then the nickel foam, nickel substrate and pure tin block were respectively placed in a 0.5% nitric acid alcohol solution for ultrasonic cleaning for 5 min to remove surface insoluble chlorides; finally, the nickel foam, nickel substrate and pure tin block were respectively immersed in an alcohol solution, ultrasonically cleaned for 5 min and then naturally air-dried for use; (b) placing the pure tin block obtained in step (a) into a high temperature resistant crucible, and then placing it on a constant temperature heating platform at a temperature of 300° C. to heat and melt it; (c) coating the nickel foam obtained in step (a) with flux on one side and then completely immersing it in the molten tin obtained in step (b) for 5 s; (d) The tin and nickel foam composite solder sheet obtained in (c) was compressed to 100 μm at 300 °C and 0.3 MPa using a hot press, and the composite solder sheet was punched into 2×2 mm solder sheets; (e) placing the welding piece obtained in (d) at the center of the nickel substrate obtained in step (a), and then placing another nickel substrate on top of the welding piece to form a sandwich structure, which is then welded at 300 °C and 0.5 MPa by hot pressing or the like.

2. The method for preparing a Ni3Sn4 / nickel foam composite joint for high temperature packaging according to claim 1, characterized in that: The specific steps of step (a) are: (1) Pure tin blocks include but are not limited to pure tin, tin alloys with a tin content of 99.3% and a nickel content of 0.7%, and one or more of the SAC series solders; (2) The pore size of nickel foam is between 5 and 500 ppi, the thickness is between 0.1 and 40 mm, and the porosity is between 50% and 98%; (3) The material of the nickel substrate includes but is not limited to pure nickel, one or more types of nickel, and the size includes but is not limited to 5×5×0.1mm.

3. The method for preparing a Ni3Sn4 / nickel foam composite joint for high temperature packaging according to claim 1, characterized in that: The specific steps of step (b) are: (1) The pure tin block melting method includes but is not limited to a constant temperature heating platform, a vacuum furnace, etc.; (2) Pure tin block melting containers include but are not limited to crucibles, pottery, etc.; (3) The heating temperature of the constant temperature heating platform is between 250 and 500 °C.

4. The method for preparing a Ni3Sn4 / nickel foam composite joint for high temperature packaging according to claim 1, characterized in that: The specific steps of step (d) are: (1) The compression method of the composite solder sheet includes but is not limited to hot press, vacuum hot press furnace, etc.; (2) The compression temperature of the composite solder sheet is between 250 and 500 °C; (3) The compression pressure of the composite solder sheet is between 0.3 and 600 MPa.

5. The method for preparing a Ni3Sn4 / nickel foam composite joint for high temperature packaging according to claim 1, characterized in that: The specific steps of step (e) are: (1) The welding methods between the composite solder sheet and the Ni substrate include but are not limited to hot pressing welding, reflow soldering, wave soldering, etc.; (2) The welding temperature between substrates is between 250 and 500 °C; (3) The welding pressure between the substrates is between 0.5 and 100 MPa.

Images