The Investigation on Microstructures, Mechanical and Wetting Properties of Sn-Zn-Ag-xAl-yBi Solder Alloys
| Autor: | Keng-Li Lin, 林耿立 |
|---|---|
| Rok vydání: | 2008 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 96 The microstructures, mechanical properties and wettability of Sn-8.55Zn-0.5Ag-xAl-yBi (x = 0.01, 0.05 and 0.1. y = 7.5, 10, 15 and 20 wt. % )lead-free solder alloys were investigated. The purpose of this research is to find the best composition to replace the Sn-Pb solder. The micorstructures of SEM show that when added 0.5 wt. % Ag to the Sn-Zn eutectic alloy, the AgZn3 compound formation and the matrix of this alloy become the Sn-Zn hyper-eutectic composition. When added 0.01 ~ 0.1 wt. % Al element to solder, the P-Zn (Primary-Zinc) phase become thicker. When add 7.5 ~ 20 wt. % Bi element to solders, the P-Zn phase precipitate increasely and the matrix change Sn-Zn hypo-eutectic composition into Sn-Zn hyper-eutectic composition, and the Bi-rich be precipitated in the matrix. After thermal stabilization at 120 °C, the precipitates in the matrix become coalesced and ball-like. When the Al element content above 0.05 wt. %, it be precipitated at the grain boundary after thermal stabilization. The result of mechanical properties shows that when added 0.01 ~ 0.1 wt. % Al element to this alloy, the mechanical strength and total elongation enhanced. The UTS of Sn-8.55Zn-0.5Ag-xAl solders are increased from 42.0MPa to 46.7, 48.4, and 50.1 Mpa respectively. The yield stress is increased from 34.1 to 38.0, 41.0 and 41.7 MPa. The Vicker’s microhardness is increased from 16.9 HV to 17.9, 21.0 and 21.5 HV. The total elongation is increased from 41.9 to 44.7, 53.4 and 56.0 %. When added 7.5 wt. % Bi element to the solder, the mechanical strength is increased dramatically, the UTS is increased from 42.0 MPa to 93.0 MPa. The yield strees is increased from 34.1 to 87.5 Mpa. The Vicker’s microhardness is increased from 16.9 HV to 27.2 Hv. Then, when added 10 ~ 20 wt. % Bi element to this alloy, themechanical strength will not be improved further, but the total elongations decrease with the Bi content increased, those decrease from 41.9 % to 26.4, 24.1, 22.1 and 17.9 % respectively. The results of mechanical properties on Sn-8.55Zn-0.5Ag-xAl-yBi solders were similar with the Sn-8.55Zn-0.5Ag- yBi solders. The results of the wettability to Cu substrate indicates, when added 0.01 ~ 0.1 wt. % Al element or 7.5 ~ 20 wt. % Bi element can enhance the wettability of solder/Cu substrate, and when added both of them, the better efftct have. The contact angle of Sn-8.55Zn-0.5Ag-xAl solders with Cu substrate decrease from 42.2° to 38.5°, 36.1° and 35.5° respectively. The contact angle of the Sn-8.55Zn-0.5Ag-yBi solders with Cu substrate decrease from 42.2° to 33.0°, 31.2°, 23.0° and 10.6° respectively. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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