BiSbAg-series high-temperature lead-free solder and preparation method thereof

Abstract

The invention discloses a BiSbAg-series high-temperature lead-free solder and a preparation method thereof and belongs to the technical field of high-temperature soft solders. The lead-free solder contains the following components in percentage by weight: 2.0-10.5% of Sb, 1.6-4.0% of Ag and the balance of Bi and a small number of unavoidable impurities, and the weight percentages of Sb and Ag in the solder alloy meet a relational expression, namely b=-0.046a<2>+0.67a+1.11+c, wherein the value of a is the weight percentage of Sb, the value of b is the weight percentage of Ag, and the value of c is larger than or equal to 1.0 and smaller than or equal to 1.0. The invention also discloses a preparation method of the lead-free solder. A microstructure of the solder alloy disclosed by the invention is a quasi-peritectic or approximate quasi-peritectic structure, and the solder alloy is small in melting range, favorable in mechanical property and reliability and suitable for the field of high-temperature soft solders.

Description

technical field [0001] The invention relates to a BiSbAg high-temperature lead-free solder and a preparation method thereof, belonging to the technical field of high-temperature solder. Background technique [0002] Most of the known chip connection methods use high-temperature solder to connect the semiconductor chip in the integrated circuit to the lead frame to form a mechanical connection and enable heat conduction and electrical conduction between the chip and the lead frame. With the development of miniaturization and multi-function of electronic equipment, advanced electronic packaging technology has also developed, such as flip-chip (FC) packaging technology, multi-chip module (MCM) packaging technology, etc. In high-end flip-chip packaging, high-temperature solder is also required; in multi-chip module packaging, multi-step soldering is often required, in which high-temperature solder is used first for primary packaging to ensure that low-temperature solder is used ...

AI Technical Summary

Problems solved by technology

Although some research results suggest that the elongation of Bi alloy wire is better than that of SnAg25Sb10 alloy (J alloy), the plasticity of Bi-Ag solder is still very low, and the strength of Bi-Ag alloy increases with the increase of Ag content, but overall its The strength is lower than that of J alloy, and it also increases the cost of the alloy

[0007] Honeywell International Corporation patent CN1507499A discloses the Bi-Ag high-temperature lead-free solder, which further adds one or more of Ni, Ge, P elements to improve the oxidation resistance of the solder, but the brittleness of the alloy It is still difficult to solve; the patent CN102892549A of Indium Corporation of the United States discloses a mixed alloy solder paste, which is mixed with the first solder alloy powder, the second solder alloy powder and flux, and uses the research idea of ​​compound addition; Japanese Senju Corporation The patent EP1952934A1 mixed the second and third particles in the Bi matrix powder to improve the mechanical properties of the Bi-based alloy. Although a better effect was obtained, on the one hand, the size of the mixed second particles or reinforcing particles was relatively large. On the other hand, Bi-Sn based alloys are selected to add Sb and Ag elements, which belong to the category of Bi-Sn hypereutectic alloy system. There will be coarse primary Bi phase in the structure, which directly affects the reliability of the alloy solder.

Therefore, the improvement of solder joint performance is still not significant

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