摘要：传统的Sn-Pb钎料由于其对人体的毒性而被各国限制使用，无铅钎料的研究随之兴起。其中，Sn-Zn系钎料由于熔点最为接近传统的Sn-Pb钎料，而被广泛关注，但它在润湿性能方面的劣势也导致无法真正投入使用。研究表明金属合金化能够改善Sn-Zn钎料的润湿性能。本文旨在研究Ga对Sn-Zn系无铅钎料组织和性能的影响。

润湿平衡试验的结果表明，Ga元素的添加对Sn-Zn钎料润湿性能有改善作用，其最佳添加量为0.5wt.%。因为Ga会在钎料表面富集，阻止Zn氧化，同时降低钎料表面张力，从而改善了润湿性。

金相组织观察的结果显示，Sn-Zn合金组织是由灰色富Sn相与针状富Zn相组成的共晶组织。由于Ga的添加，Sn-9Zn钎料组织变得均匀，且在Ga含量为0.5wt.%时效果最佳，当Ga含量达到2wt.%，在合金组织中出现了呈黑色的富Ga相。

焊点力学性能的结果表明，添加0.5wt.%的Ga元素后，焊点的力学性能得到了一定改善，而当Ga添加量达到2wt.%时，焊点晶界处会形成低强度富Ga相，降低了焊点力学性能，断口也由原来的韧性断裂变成了沿晶断裂。

关键词：Sn-9Zn钎料，Ga，润湿性能，焊点力学性能，显微组织

Title：Effect of Ga on Microstructure and properties of Sn-Zn based lead free solder

Abstract：Due to the toxicity of Pb , the traditional Sn-Pb solder is to halt production by various countries.Therefore, the research of lead-free solder has attracted much attention all over the world. Sn-Zn solder has attracted much attention in lead-free solders due to its low melting point.However, due to its low oxidation resistance and poor wetting properties, this solder is not able to be applied to electronic products. In this paper,the effect of Ga on the microstructure and properties of Sn-Zn lead-free solder was studied , according to the development of lead-free solder and the characteristics of the production process.

After the wetting balance test, it’s find that the optimum Amount added of Ga in Sn-9Zn solder is about 0.5wt.%. As an active element, Ga is often enriched in the surface of solder，thus to enhance antioxidant capacity and Improve wettability.

Metallographic observation showed that Sn-9Zn lead-free solder is composed of Sn rich gray matrix structure and rich Zn black needle like structure. The two phase structures are Zn solid solution in Sn, eutectic phase of beta -Sn phase and rich Zn phase. When the content of Ga is 0.5wt.%, the grains of microstructure are small and a fine microstructure is obtained and When the Ga element reaches 2wt.%, the black rich Ga phase appears.

The mechanical property test of solder joint shows that there is no obvious change in mechanical property after adding 0.5wt.% Ga, and the pull force is enhanced by 2.8% and when the additive amount of Ga is upto 2wt.%,an elliptic rich Ga phase is formed at grain boundaries ,the fracture shows intergranular fracture and the mechanical properties of solder joints are greatly reduced.

Keywords：Sn-Zn lead-free solder,Ga, solderability, mechanical property, microstructure

目录

第一章 绪论 4

1.1 引言 4

1.2 无铅钎料的研究现状 4

1.2.1 Sn-Ag系钎料 5

1.2.2 Sn-Cu系钎料 5

1.2.3 Sn-In系钎料 5

1.2.4 Sn-Bi系钎料 5

1.2.5 Sn-Zn系钎料 6

1.3 Sn-Zn系无铅钎料研究现状 6

1.3.1 Sn-Zn系无铅钎料的合金化 7

1.3.2 Sn-Zn无铅钎料助焊剂的研究 9

1.4 本章小结 10

第二章 试验过程及研究方法 10

2.1 合金的制备 11

2.2 润湿平衡试验 11

2.3 金相组织分析 13

2.4 焊点力学性能试验 15

第三章 Ga对钎料润湿性能和显微组织的影响 16

3.1 Ga对Sn-9Zn钎料润湿性能的影响 16

3.2  Ga对Sn-9Zn无铅钎料组织的影响 18

3.3 本章小节 19

第四章 Ga对Sn-9Zn钎料力学性能的影响 20