Sn-Ag-Cu lead-free solder with high interface bonding strength and a preparation method thereof

Abstract

The invention discloses improved Sn-Ag-Cu lead-free solder and a preparation method thereof. Zr and Ni are added in Sn-Ag-Cu lead-free solder, the amount of the Zr and the amount of the Ni are controlled, addition of the Ni can further promote the dispersion distribution of the Zr so as to further refine the microstructure of the solder; the surface tension of a molten pool is reduced, a wetting and spreading area is expanded, and the welding wettability and the oxidation resistance of a solder alloy are improved; and formation of the defects such as cavities and bridging in the welding process is inhibited, surface oxidation of welding spots during the long-term use process is prevented, and the welding spots still have excellent electricity and heat conduction performance in long-term use. By means of the synergistic effect of the two elements, the welding wettability as well as the mechanical property, the high-temperature anti-aging performance and the electricity conduction and heat conduction performance of the welding spots are comprehensively improved, and the development requirements of electronic components are met.

Description

technical field [0001] The invention relates to a brazing material and a preparation method thereof, in particular to a Sn-Ag-Cu lead-free solder with high interface bonding strength and a preparation method thereof. Background technique [0002] Surface mount technology (SMT) has experienced nearly half a century of development since its inception. It has not only become the mainstream of contemporary circuit assembly technology, but also is developing in depth, promoting electronic products to miniaturization, light weight, high precision and high reliability. The direction of development has increased the number of I / O pins in the circuit, the number of solder joints has increased, the size has become smaller, and the spacing has become narrower and narrower. The sharp reduction in the size of solder joints poses a challenge to the performance and reliability of electronic solder. Studies have shown that 70% of the failures of electronic devices are caused by the failure...

AI Technical Summary

Problems solved by technology

[0009] (1) The alloy composition is not a standard eutectic alloy composition, it is easy to form a pro-eutectic phase, the structure is coarse, and the mechanical properties are deteriorated;

[0010] (2) Wetting performance of alloy welding is slightly reduced, and welding defects such as bridging and voids are prone to occur;

[0011] (3) The anti-oxidation and corrosion performance is not high. During the welding process, the solder and the pad are easily oxidized, making it difficult to form a firm metallurgical bond between the solder and the pad, which reduces the conductivity of the solder joint.

At the same time, there is also a risk of surface oxidation during the service of solder joints;

[0012] (4) During the service process of solder joints, the intrinsically brittle intermetallic compound at the interface between the solder and the substrate grows excessively, and the solder joints crack along the interface when subjected to vibration, mechanical shock and other conditions, resulting in failure of the solder joints

[0016] The existing Sn-Ag-Cu lead-free solder has relatively complex composition, high cost and unsatisfactory performance

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