Molybdenum-copper alloy heat sink ultrasonic-assisted diffusion bonding manufacturing method based on pulse current heating and diffusion welding device

Abstract

The invention provides a molybdenum-copper alloy heat sink ultrasonic-assisted diffusion bonding manufacturing method based on pulse current heating and a diffusion welding device. The molybdenum-copper alloy heat sink ultrasonic-assisted diffusion bonding manufacturing method comprises the following steps that to-be-welded faces of molybdenum-copper alloy and copper are cleaned and dried; a copper sheet is placed on the upper surface of a lower electrode block of a pulse current plasma diffusion welding furnace, and a molybdenum-copper alloy sheet is placed on the copper sheet; applying pre-pressure to the material by using an upper pressure head and a lower pressure head of a pulse current plasma diffusion welding furnace; vacuumizing until the air pressure in the diffusion welding furnace is lower than a preset value, starting a pulse current generator, and heating to a diffusion welding temperature; preset axial pressure is applied to the plate, and welding is conducted; the ultrasonic generator is closed, and axial pulse pressure is applied to the plate; and after welding is finished, the pulse current generator is closed, and the axial pressure is removed. After ultrasonic-assisted welding, pulse pressure welding is adopted, so that abnormal growth of plate grains can be avoided, intermetallic compounds formed between joints are effectively broken, the harmful effect of the intermetallic compounds on the joints is reduced, and the bonding strength of the joints is improved.

Description

technical field [0001] The invention relates to the technical field of packaging in the fields of electronics and optoelectronics, in particular to a manufacturing method and application of a molybdenum-copper alloy heat sink based on pulse current heating and ultrasonic-assisted diffusion connection. Background technique [0002] With the continuous development of industrial technology, the power of electronic equipment used in high-tech fields such as national defense, electronic industry, new energy, aerospace and other high-tech technologies is getting larger and larger, and the integration level is getting higher and higher, which will generate a lot of heat during the working process. , the heat dissipation problem has become a bottleneck restricting the development of these industries. Traditional single metal has been difficult to meet the needs of industrial production in complex service environments; therefore, people began to use the excellent characteristics of d...

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Problems solved by technology

[0004] Since the physical and chemical properties of molybdenum and copper are very different, it is difficult to achieve the connection of these two materials

At present, the technical difficulties of its connection mainly include: (1) The melting point, thermal expansion coefficient and thermal conductivity of molybdenum and copper are very different. It is difficult to obtain a satisfactory joint when using traditional welding methods for welding

(2) The difference in thermal expansion coefficient between molybdenum and copper will lead to different instantaneous thermal expansion of welding, and obvious thermal deformation of welded parts will cause the workpiece to fail

(3) Molybdenum, copper and oxygen have a high affinity and are easily oxidized to form an oxide film. The existing film removal method is not ideal and cannot prevent the appearance of a secondary oxide film, thereby affecting the surface contact between molybdenum and copper.

The coating prepared by the thermal spraying method has low density and is prone to pores; the interface bonding strength obtained by the rolling cladding method is not high; the laser cladding method is difficult to achieve the metallurgical bonding effect because of the immiscibility between molybdenum and copper; the impact of the explosive cladding method The noise is high, the material is prone to cracks, and is limited by the site; diffusion welding can realize the connection of molybdenum and copper, which have greatly different properties and are insoluble in each other, but the traditional diffusion connection needs to be heated in a heating furnace as a whole, and the heating rate is slow. When welding, the temperature is high, the atomic diffusion rate is low, the welding cycle is long and there are intermetallic compounds between the interfaces

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