Composite gradient laminated solder preform for power electronics and manufacturing method thereof

Abstract

The invention relates to a composite gradient laminated solder preform for power electronics and a manufacturing method thereof, comprising: a composite preform body, the body is formed by pressing Cu / Sn / Ag core-shell powder; the Cu / Sn / Ag core-shell structure powder is prepared by electroplating Sn on Cu powder with different particle sizes to prepare Cu / Sn powder, and then sputtering and plating Ag on Cu / Sn powder to obtain Cu / Sn / Ag powder; the surface of the body is made of Multi-layer composite gradient lamination, the thickness of each layer of composite gradient lamination gradually increases from the inside to the outside; the multi-layer composite gradient lamination adopts the physical vapor deposition process to carry out the first melting point and the second melting point respectively on the upper and lower surfaces of the body. Alternate metal sputtering coating treatment to complete the preparation, the temperature of the first melting point is higher than the second melting point. The present invention prepares gradient multi-layer coatings on the surface of the preformed soldering sheet, and at the same time electroplates a Sn layer on the surface of the copper-clad ceramic substrate (DBC). Soldered joints with thermal resistance and high mechanical reliability.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a composite gradient laminated preform for power electronics and a manufacturing method thereof. Background technique [0002] Power electronic modules are used more and more widely in electric vehicles, aerospace, rail transit, etc. The third-generation wide-bandgap semiconductors such as SiC, because of their high melting point, high power density, and superior thermal and electrical conductivity, have become the best materials to replace Si chips. To give full play to the superior performance of SiC chips, high-temperature-resistant chip soldering materials and soldering Technology is the key and constraint. [0003] Traditional high temperature soldering materials include Au-Sn, Bi-Ag-xSn-xPb, Sn-Pb-Ag. Due to the high cost of Au and Ag precious metals, the soldering temperature is 280-330°C, which affects the performance of temperature-sensitive components; with the promul...

AI Technical Summary

Problems solved by technology

The thickness of the welding layer using this welding technology is generally less than 20 μm, which is not conducive to absorbing the thermal stress caused by the adaptation of the thermal expansion coefficient of system materials such as chips and substrates, and it is difficult to meet the needs of high-reliability packaging of power electronic devices

Chinese patent CN100475996C discloses a composition, production method and components for high-temperature lead-free solder. The phase line is not lower than 262.5°C, and the liquidus line is not higher than 400°C. However, the strength and plasticity of the lead-free solder composition are low, and the solder paste made of ordinary solder paste for this solder has poor collapse resistance. , more tin beads and other defects are unfavorable for the industrialized production and promotion of the composition for lead-free solder

The amount of precious metals is large, the cost is high, and the welding temperature is high; Chinese patent CN104588906 A discloses a Sn-Cu high-temperature lead-free solder paste and its preparation method and use method. High shear strength and stable performance, but this technology still uses solder paste, which requires a screen printing process that is prone to pollution; due to the welding process, the solder material cannot be wetted and spread, so a large area is left after the solder paste volatilizes Holes and loose joints affect thermal conductivity and reliability; Chinese patent CN103753049A discloses a Cu / Sn composite solder preform, although it solves the problem of large voids caused by volatilization of solder paste, it still has poor toughness and strong toughness. The problem of mismatch, at the same time, there is non-coplanarity with the chip and the substrate, and the interface is difficult to achieve dense welding, resulting in large contact thermal resistance, poor mechanical properties, and low reliability.

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