A kind of preparation method of copper core ball

Abstract

The invention discloses a preparation method of a copper-core solder ball. The method includes following steps: electrolyzing a copper block, and preparing molten-state copper liquid by a copper block raw material through an electrolytic process; injecting the molten-state copper liquid into a cavity of a molding device, wherein the lower end of the molding device is provided with a plurality of capillary tubes; feeding nitrogen downwardly from the top end of the molding device; and the copper liquid is wrapped by the nitrogen and molded at the bottom ends of the capillary tubes. According to the prepared copper-core solder ball, the excellent effect is presented in the reliability assessment of soldering joint; during comparison of an electroplated SAC305 copper-core solder ball and an SAC305 solder ball, the drop test result of the copper-core solder ball is far superior to the test of the solder ball, and test results of temperature cycling of the copper-core solder ball and the solder ball are the same; and in general, the prepared copper-core solder ball and the SAC305 solder ball have the same thermal-fatigue resistance, the poor drop impact of high-silver materials can be overcome, and the yield of the product can be guaranteed.

Description

technical field [0001] The invention relates to the technical field of manufacturing electronic components, in particular to a method for preparing copper core balls. Background technique [0002] In recent years, the market demand for mobile electronic products has expanded rapidly. Taking smart phones as an example, the sales volume of smart phones in China rose from 96 million units in 2011 to 420 million units in 2015. With the development of lightweight, thinner and multi-functional mobile electronic products, traditional electronic packaging technology cannot meet the requirements of miniaturization, narrow pitch and multi-pin. In order to meet these market requirements, 3D packaging technology represented by package-on-package (POP) emerged as the times require. 3D packaging originated from the stacked packaging of flash memory and SDRAM. It is a packaging technology that stacks more than two chips in the same package in the vertical direction without changing the si...

AI Technical Summary

Problems solved by technology

[0005] 3D packaging requires multiple thermal processes, while traditional BGA solder balls are repeatedly heated at 250°C, and the solder bumps will melt, which will cause unacceptable deformation of the solder bumps under the weight of multi-layered electronic components, resulting in The packaging space is narrowed, and problems such as adhesion and short circuit between solder joints or between solder joints and parts

[0007] However, the disadvantage of the method for preparing copper core balls disclosed in the reference document is that the copper balls prepared by the atomization method or the physical vapor phase method have poor shape regularity and poor roundness, resulting in a low yield rate. , the surface of the copper ball prepared by the above method is irregular and uneven, so that when nickel plating is performed, interdiffusion between atoms will easily occur between the nickel layer and the copper layer to form a metal compound, thereby affecting the product. Performance, on the other hand, the above preparation method does not take into account the oxidation phenomenon of copper balls during the molding and aging process