| 摘要: | 本研究在探討Bi-2.5 Ag合金中，藉由分別添加1.0 wt. %之In、Sb及Sn元素，與Cu基材之球格狀陣列(Ball Grid Array, BGA)構裝時，預期能與合金中的Bi元素、Ag元素及基材的Cu元素間生成介金屬化合物，以改善銲接強度發散的問題，進而討論三元合金銲料之熔融行為、顯微組織，接合界面組織與機械性質的變化。
熱熔融結果顯示: Bi-2.5 Ag合金在262.2 ℃有吸熱反應，經添加1.0 wt.% In及Sn元素至Bi-2.5 Ag合金中時，分別出現Bi-In低溫相(109.5 ℃)及Bi-Sn低溫相(138.8 ℃)。至於添加1.0 wt.%Sb後，其熔融溫度反而比Bi-2.5Ag合金升高約1.1℃(即熔融在263.3℃)。
Bi-2.5 Ag-1.0 X (X=In,Sb及Sn)合金與Cu基材經迴銲1~5次後之微結構顯示: Bi-2.5Ag及Bi-2.5Ag-1.0 In合金的銲接點，於接合界面上均未發現介金屬化合物；至於Bi-2.5 Ag-1.0 Sn與Bi-2.5 Ag-1.0 Sb合金在銲接後，於銲點靠近Cu基材之富Bi相基地處，分別形成帶狀Cu3Sn化合物以及帶狀Cu2Sb化合物。
以推球方式量測銲接點之剪切力，結果顯示: Bi-2.5Ag合金在添加1.0 wt.% 之In, Sb 及 Sn等元素後，銲點剪切力及穩定性均有提升效果，剪切力由高至低分別為Bi-2.5 Ag-1.0 In (2.0±0.12mN) > Bi-2.5 Ag-1.0 Sn (1.7±0.18mN) > Bi-2.5 Ag-1.0 Sb(1.5±0.13mN) > Bi-2.5Ag合金(1.4±0.24mN)。經由5次迴銲後，添加Sb元素及Sn元素對於銲點剪切力的提升幅度較為明顯，相較1次迴銲銲點剪切力分別增加40%及35%。
;The motivation of this thesis is to modify the solder joints strength issue when Bi-2.5Ag soldered with Cu pad of ball grid array (BGA) with addition of 1.0 wt.% In, Sb and Sn. Subsequently the melting behavior, microstructure, interface microstructure and mechanical properties of ternary alloys have been discussed.
The thermal analysis shown that, Bi-2.5Ag has a endothermic reaction at 262.2 ℃. After adding of 1.0 wt.% In and Sn, low temperature Bi-In phase (109.5 ℃) and Bi-Sn phase (138.8 ℃) are appeared separately. However after adding of 1.0wt.% Sb, the melting point is increased about 1.1℃ to 263.3℃.
The microstructure of Bi-2.5Ag-1.0X (X=In, Sb, Sn) with Cu pad after multiple reflows shown that, there are no intermetallic compound (IMC) found at Bi-2.5Ag and Bi-2.5Ag-1.0 In joints. For Bi-2.5Ag-1.0Sn and Bi-2.5Ag-1.0 Sb, band-like Cu3Sn and band-like Cu2Sb are found at the interface of the joints.
The solder joints strength had been tested by ball shear test, the result shown that after adding 1.0 wt.% In, Sb and Sn, the shear force and stability had been increased. The order of shear force (from high to low) is Bi-2.5Ag-1.0In (2.0±0.12mN) > Bi-2.5Ag-1.0Sn (1.7±0.18mN) > Bi-2.5 Ag-1.0Sb (1.5±0.13mN) > Bi-2.5Ag (1.4±0.24mN). Comparing the result of 1 time reflow and 5 time reflow, the Sb and Sn addition ternary alloys shown significant enhance, the shear force had been increased 40% and 35% separately. |
