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Nuclear shell structure Pb-free solder ball for electronic packaging and preparation method thereof

A lead-free solder ball, core-shell structure technology, applied in the direction of welding equipment, welding medium, manufacturing tools, etc., can solve the problems of lack of core-shell structure, cooling speed reduction, small solder ball diameter, etc., to achieve high conductivity and high heat The effect of high conductivity and high connection strength

Inactive Publication Date: 2010-02-10
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The object of the present invention is to provide a lead-free solder ball with core-shell structure for electronic packaging and its preparation method, which overcomes the shortcomings of small solder ball diameter, reduced cooling rate, and lack of core-shell structure.

Method used

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  • Nuclear shell structure Pb-free solder ball for electronic packaging and preparation method thereof
  • Nuclear shell structure Pb-free solder ball for electronic packaging and preparation method thereof
  • Nuclear shell structure Pb-free solder ball for electronic packaging and preparation method thereof

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Embodiment Construction

[0027] (1) Alloy smelting

[0028] The alloy was melted in two steps. The first step is to weigh the metal Cu and Sn according to the weight ratio of 3:2, put them into the induction melting furnace, pass in argon gas, heat up to 1100°C to melt the alloy and then cool it down, repeat 3 times until the mixture is uniform; the second step , Weigh the Bi block according to the ratio of CuSn alloy 1:1.5. The rare earth metals that can effectively promote the formation of the core-shell structure include the pure metals and their mixtures listed in the table below, the addition of which is 0.05% (mass fraction), metal Bi, rare earth metals and pre-melted Cu-Sn alloy blocks are smelted again , the maximum temperature is 800°C.

[0029]

[0030] (2) Gas atomization

[0031] The uniformly melted alloy melt is atomized into liquid droplets by 0.2MPa high-pressure argon gas, cooled and solidified in the atomization tank to form a complete solder ball.

[0032] (3) Collect, wash, ...

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Abstract

The invention relates to a nuclear shell structure Pb-free solder ball for electronic packaging and a preparation method thereof, belonging to the technical field of Sn-based Pb-free brazing alloy. The solder ball contains the following chemical components by mass percent: 47-68% of Bi, 19-32% of Cu, 13-21% of Sn and 0.01-1% of rare earth metal. The diameter of the solder ball is 0.10-0.76mm. Thesolder ball has a nuclear shell structure, the nuclear core is a Cu-rich phase, and a layer of Sn-Bi-rich alloy is evenly coated on the shell. The Pb-free solder ball of the nuclear shell structure can be applied to BGA packaging. Peripheral low-melting point SnBi alloy mainly plays a role of connecting components in jointing, while internal high-conductivity Cu-based alloy plays a role of circuitconnection, which can meet the demands of high connection strength, high conductivity and high heat conductivity of electronic packaging.

Description

technical field [0001] The invention belongs to the technical field of tin-based lead-free solder, in particular to a core-shell structure lead-free solder ball for electronic packaging and a preparation method thereof. Background technique [0002] At present, ball grid array packaging (BGA packaging) is gradually becoming the mainstream of electronic packaging technology. This technology uses solder balls to replace the pins in the IC component packaging structure to meet the requirements of electrical interconnection and mechanical interconnection. One of its core technologies is the preparation of high-quality solder balls. Most of the solder balls currently on the market are Sn-Pb alloys. Since lead and its compounds are highly toxic substances, they are extremely harmful to human health and the environment. At present, all countries in the world have or are in the process of banning the production and sale of leaded solder, thus accelerating the research of lead-free ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K35/28B23K35/40
Inventor 李建强马炳倩臧丽坤徐红艳
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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