A method for in-situ toughening of strong and tough integrated cu/sn/ag welding materials

Abstract

An in-situ toughening method for a strong and tough integrated Cu / Sn / Ag welding material, step (1) evenly electroplating a layer of 2-3 μm Sn coating on copper particles with different particle sizes, and then physically and uniformly depositing on the surface of Cu / Sn powder One layer of ~1μm Ag layer to obtain Cu / Sn / Ag powder; Step (2) Proportioning the Cu / Sn / Ag powder prepared in step (1), placing it in a mixer, at a speed of 100~300r / min and mechanically mixing for 1-2 hours to obtain a powder with a uniform particle size; step (3) press-molding the powder prepared in step (2) on a high-pressure tablet press, and the pressure range of the high-pressure tablet press is 10-30 MPa, Obtaining a Cu / Sn / Ag composite solder preform with a thickness of 100-400 μm; step (4) performing low-temperature transient liquid-phase diffusion welding on the composite solder preform, at a melting point lower than Sn, through Sn Simultaneous diffusion reaction with Cu, Sn and Ag, so that the low melting point Sn is completely converted into high temperature resistant Cu 3 Sn and Ag 3 Sn interface intermetallic compound, prepared Cu 3 Sn / Ag 3 Three-dimensional network structure joints of Sn-coated Cu particles.

Description

technical field [0001] The invention relates to a lead-free solder preform of a high-temperature-resistant three-dimensional network joint for power electronic packaging and an in-situ toughening method for a strong and tough integrated Cu / Sn / Ag welding material. Background technique [0002] Power electronics (or power) modules are important energy conversion and control devices, widely used in aerospace, rail transit, advanced energy, electric vehicles, oil drilling, major and advanced equipment manufacturing, frontier scientific research and other fields. With the development of electronic products in the direction of miniaturization, high density, and high power, and the industrial application of third-generation semiconductor devices represented by SiC, power electronic modules are facing the challenges of higher temperature tolerance and higher reliability. The comprehensive lead-free module is gradually put on the agenda, and the corresponding lead-free packaging join...

AI Technical Summary

Problems solved by technology

[0003] Typical "sandwich" metal structure-LT-TLPB is a high temperature resistant pure interfacial intermetallic compound (IMCs) joint, which is based on low melting point metals such as Sn and In in the middle layer, and Cu, Ni, Au, Zn, etc. in the surface layer The sandwich structure of high-melting-point metals uses the melting of low-melting-point metals to produce liquid-solid interdiffusion, and generates high-temperature-resistant IMCs as a welding technology for connecting joints. The thickness of the welding layer using this welding technology is generally less than 20 μm, which is not conducive to absorbing due to chips and The thermal stress generated by the adaptation of the thermal expansion coefficient of system materials such as substrates 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

CN104476007A discloses a high-melting point lead-free halogen-free solder paste and its preparation method. The solder paste solder alloy has a solidus temperature higher than 260°C and has the advantages of high strength, high plasticity, and strong fatigue resistance. Soldering paste has complex process, easy to pollute the chamber, and the porosity of the prepared joints is large; Chinese patent CN101234456A discloses a tin-silver-gold lead-free soldering material and its preparation method. Its melting temperature can reach 300 ° C, wet Excellent electrical and electrical properties, good welding effect, can replace the traditional Sn-95%Pb solder alloy

The amount of precious metal is large, the cost is high, and the welding temperature is high; Chinese patent CN104588906A discloses a Sn-Cu high-temperature lead-free solder paste and its preparation method and use method. The shear strength is high, but the elasticity and plasticity are insufficient, and this technology still uses solder paste, which needs to adopt a screen printing process that is prone to pollution; due to the welding process, the solder material cannot be wetted and spread, so the solder paste is left behind after volatilization Large-area holes and loose joints affect thermal conductivity and reliability; Chinese patent CN103753049A discloses a Cu / Sn solder sheet with high temperature resistance, but Cu 3 The Kirkendall voids produced by the Sn generation process are high, and the thermal and electrical conductivity are affected. In addition, the elastic modulus of the Cu particles is high, the joint toughness is insufficient, and the reliability at high temperatures is difficult to meet the requirements.

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