Sn-based brazing filler metal capable of realizing vertical stacking of chips and bonding method of Sn-based brazing filler metal

Abstract

The invention discloses Sn-based brazing filler metal capable of achieving vertical stacking of chips and a bonding method of the Sn-based brazing filler metal. The Sn-based brazing filler metal comprises aluminum oxide nanofibers, nano palladium particles, Bi and Sn. The coupling effect of the aluminum oxide nanofibers, the nano palladium particles, Bi and Sn is utilized for strengthening welding spots, Bi-rich and IMC crystal grains can be tightly wound together by adding the aluminum oxide nanofibers, the nano palladium particles can be gathered at the grain boundaries of the Bi-rich and IMC crystal grains, the effect of pinning the aluminum oxide nanofibers and the grain boundaries is achieved, the aluminum oxide nanofibers and the nano palladium particles are coupled to reinforce the welding spots, so that the welding spots still keep higher strength and longer service life during the service period; the Sn-based brazing filler metal has good wettability and higher welding spot mechanical property, can meet the high reliability requirement of vertical stacking of high-density packaging and three-dimensional packaging electronic device chips, and can be used for wave soldering, reflow soldering and other brazing methods.

Description

technical field [0001] The invention relates to a Sn-based solder and a bonding method thereof, in particular to a Sn-based solder capable of realizing vertical stacking of chips and a bonding method thereof, and belongs to the technical field of chip-level packaging. Background technique [0002] With the development of Moore's Law, the miniaturization and multifunctionalization of electronic devices have become the engine for the development of the integrated circuit industry. The vertical stacking and interconnection of chips in three-dimensional space has successfully promoted the development of electronic products in the direction of miniaturization, integration and multi-function. Stacking technology is mainly used in various hardware, including 3D stacked memory, graphics processing unit (GPU), field programmable gate array (FPGA) and CMOS image sensor (CIS). According to the research report of the research institution YOLE, by 2023, The total value of the chip stack...

AI Technical Summary

Problems solved by technology

The Sn-based lead-free solder disclosed in U.S. Patent US10434608B2 includes (1.2-4.5%) Ag, (0.25-0.75%) Cu, (1.0-5.8%) Bi, (0.01-0.15%) Ni, and the rest is Sn. By optimizing the content of alloying elements, the wettability of solder, the shear performance of solder joints and the thermal fatigue resistance are enhanced to a certain extent. This patent is mainly aimed at conventional SMT (Surface Mounted Technology) solder joints. The solder joints are composed of intermetallic Composed of compound layer and solder matrix, conventional SMT solder joints occupy most of the solder joints due to the short soldering time, but for tiny solder joints in high-density packaging and three-dimensional packaging, intermetallic compounds occupy Most of the solder joints are removed, which leads to completely different performance, so this patented solder is not suitable for high-density packaging and three-dimensional packaging electronic devices

Another example is the Sn-based lead-free solder disclosed in Chinese patent ZL201810286715.6, which includes (3.0% to 3.1%) Ag, (0.7 to 1.0%) Cu, (3.0 to 5.0%) Sb, (3.1 to 4.5%) Bi, ( 0.01~0.03%) Ni, (0.008~0.15%) Co, and the rest is Sn. This patent adds a certain amount of Ag, Cu, Sb, Bi, Ni and Co to realize the high temperature difference and severe load vibration environment. To suppress the expansion of solder joint cracks, this patent mainly adds trace amounts of Sb and Bi and trace amounts of Ni and Co to the Sn-Ag-Cu solder, but for three-dimensional packaging all-intermetallic compound solder joints, it takes a long time to put the solder The solder is completely converted into an intermetallic compound, and the patented components Sb, Ni and Co will also be completely converted into an intermetallic compound, so the patented solder is not suitable for high-density packaging and three-dimensional packaging electronic devices

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