Improved type Sn-Ag-Zn lead-free solder for inhibiting solid state interface reaction

An interface reaction, lead-free solder technology, used in welding/cutting media/materials, welding media, manufacturing tools, etc., can solve the problems of substrate dissolution, affecting interface reliability, etc., to achieve the effect of increasing reliability

Inactive Publication Date: 2007-10-17
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

It solves the disadvantages in the prior art that the solder is easy to react with the metal of the substrate, causing a large amount of dissolution of the substrate, and at the same time, a large amount of intermetallic compounds are formed at the interface, which seriously affects the reliability of the interface. The preparation process of the lead-free solder of the present invention is simple and easy to produce

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] The solder Sn3.5Ag, its components and their mass percentages are: Zn 0.05%, Ag 3.52%, Sn 96.43%.

[0018] The solder of this embodiment is refined by the conventional smelting method of Sn-based lead-free solder. Put 100g of LiCl and KCL mixed salt with a mass ratio of 1:1.2 into the crucible and put it in a constant temperature furnace, heat it to 600°C and keep it warm, put 96.43g of Sn particles and 3.52g of Ag wire in turn, keep it warm for 2 hours, and use a vibrating rod Stir well. Cool down to 550°C, add 0.05g of Zn foil, keep warm for 2 hours and stir evenly. Lower the temperature to 300°C to keep warm, scoop out the slag, and pour it into a mold with a diameter of Φ6 for molding.

[0019] DSC melting point test showed that the solder had a melting point of 221.3°C. Process the rod-shaped sample into a disc-shaped solder of Φ5×2mm, and place it on a pure Cu plate of 25×25×0.2mm for wetting test. The wetting test is carried out in a reflow soldering machine ...

Embodiment 2

[0021] The solder Sn3.5Ag0.2Zn, its components and their mass percentages are: Zn 0.20%, Ag 3.48%, Sn 96.32%.

[0022] The preparation method is the same as in Example 1.

[0023] A DSC melting point test showed that the solder had a melting point of 221.0°C. The microscopic analysis of the Sn3.5Ag0.2Zn / Cu interface aged at 150℃ for 0, 5, 10, 15, and 20 days showed that the initial compound of the interface was Cu6Sn5, and as time went on, a Cu5Zn8 compound layer appeared, while Cu3Sn was suppressed. The compound layer thickens in a parabolic form with time, but the thickening speed is obviously lower than that of Example 1. After 20 days of thermal aging process, the thickness of the interfacial compound is 6.0 μm.

Embodiment 3

[0025] The solder Sn3.5Ag0.5Zn, its components and their mass percentages are: Zn 0.49%, Ag 3.45%, Sn 96.06%.

[0026] The preparation method is the same as in Example 1.

[0027] A DSC melting point test showed that the solder had a melting point of 219.2°C. The microscopic analysis of the Sn3.5Ag0.5Zn / Cu interface aged at 150℃ for 0, 5, 10, 15, and 20 days showed that the interface compound was mainly composed of double-layer Cu6Sn5 / Cu5Zn8, and the thickness increased parabolically with time. After 20 days of thermal aging process, the thickness of the interfacial compound layer is about 5.8 μm.

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Abstract

The present invention relates to an improved Sn-Ag-Zn solder free of lead used for inhibiting the solid state interfacial reaction, which belongs to the technical field of electronic material. The mass percentage of each component is 0.05~3.02 % of Zn, 3.43~3.52% of Ag, balance Sn. The diffusion barrier layer formed on the reaction interface can inhibit the diffusion of Cu atom, so that the growing of the intermetallic compounds on the reaction interface can be inhibited. The problem of that the solder is easy to react with the base metal to bring about the mass dissolution of the base metal and the mass intermetallic compounds formed on the interface, which can seriously affect the interface reliability, is solved. The solder free of lead of the present invention has a simple technology and is easy to realize mass production.

Description

technical field [0001] The invention relates to a solder in the field of soldering technology, in particular to an improved Sn-Ag-Zn lead-free solder that suppresses solid-state interfacial reaction. technical background [0002] Due to the great threat of Pb to the natural environment and human health, countries around the world have legislated to ban the SnPb eutectic solder that was widely used in the manufacture of electronic products in the last century. Seeking a substitute for SnPb eutectic solder has become an important task in the current electronics industry. So far, countries around the world have successively developed a series of lead-free solders, which are mainly based on Sn-Ag, Sn-Cu, Sn-Ag-Cu, Sn-Zn, Sn-Bi eutectic systems. However, even the most promising Sn-Ag-Cu eutectic or near-eutectic solders have many properties that are difficult to compare with SnPb eutectic solders. [0003] Sn3.5Ag eutectic solder has high mechanical strength, superior fatigue r...

Claims

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Application Information

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IPC IPC(8): B23K35/26
Inventor 陆皓余春陈俊梅李仕明
Owner SHANGHAI JIAO TONG UNIV
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