Investigations of Interfacial Reactions in Electronic Materials during Modularization Process

本論文主要分成兩部分探討，第一部分為液晶顯示器(liquid-crystal display, LCD)驅動IC元件之剝離測試及界面反應分析，主要觀察鍍Sn的Cu導線與Au凸塊經不同內引腳接合(inner lead bonding, ILB)參數接合後之Cu/Sn/Au界面微結構。第二部分為Ni擴散阻障層對塊材與奈米結構熱電基材與Sn-4 wt.%Ag-0.5 wt.%Cu (SAC405)銲料界面反應之影響，由於熱電材料能夠將廢熱回收轉換成電能，但其接點之界面反應亦會影響熱電模組之效能，因此接點間的界面反應亦不容忽視。 由本論文第一部份的結果可知，鍍Sn的Cu導線與Au凸塊熱壓接合後會生成ζ-(Au,Cu)5Sn相及α相；其中，α相的機械性質較差，在剝離測試後，α相中會生成微裂縫。研究結果顯示，提高熱壓溫度及增加導線崁入深度，可使Cu導線側壁的Sn包覆性增加，同時提升Cu導線與Au凸塊的接附性。本論文於第二部份的研究結果確認塊材結構熱電基材為異向性材料，而奈米結構熱電基材為等向性材料。此外，在熱電基材上電鍍Ni後，會因熱電基材表面特性之差異而沉積出不同結構之Ni層。晶粒較小且晶界數量較多的Ni層在與SAC405銲料迴銲及熱處理後，界面會生成(Cu,Ni)6Sn5相及(Ni,Cu)3Sn4相，其中，(Ni,Cu)3Sn4相成長速度相當快。反之，晶粒較大且晶界數量較少的Ni層在與SAC405銲料迴銲及熱處理後，界面僅生成(Cu,Ni)6Sn5相，且(Cu,Ni)6Sn5相成長速度較緩慢。因此，熱電模組中的電鍍Ni阻障層應使用晶粒較大的結構，較能夠減緩介金屬化合物(intermetallic compounds, IMCs)生成的速度。There are two parts in this thesis. The first part is an investigation of peeling test and interfacial reaction of the driver IC in liquid-crystal display. The Sn-coated Cu lead was bonded with Au bump using inner lead bonding technique with different bonding parameters. This study analyzed the effects of bonding parameters on interfacial reactions of Cu/Sn/Au joints after peeling test. The second part investigated the effects of Ni diffusion barrier electroplated on bismuth telluride thermoelectric materials with bulk and nano structures on interfacial reactions of SAC405/Ni/Bi2Te3 couples. Thermoelectric (TE) materials can convert waste heat into electricity. The joints in thermoelectric module may affect the module performance, so the interfacial reactions of the joints cannot be ignored. The results of the first part showed the ζ-(Au,Cu)5Sn and α phases formed between the Sn-coated Cu lead and Au bump after bonding. After peeling test, the microcracks formed inside the α phase, meaning that the mechanical property of the α phase was poor. By increasing the heating temperature and the embedded depth of lead, the adhesion strength of lead to bump was increased. The results of the second part showed the bulk thermoelectric material had an anisotropic structure and the nano thermoelectric material had an isotropic structure. After electroplating Ni, the structure of the Ni layer was dependent on the surface properties of the TE substrate. When the electroplated Ni had small grain size and high grain boundary density, the (Cu,Ni)6Sn5 phase and the (Ni,Cu)3Sn4 phase were formed at the interface between SAC405 and Ni interface after reflowing and thermal aging. Moreover, the growth rate of the (Ni,Cu)3Sn4 phase was fast. However, when the electroplated Ni had large grain size and low grain boundary density, only the (Cu,Ni)6Sn5 phase was formed at the interface between SAC405 and Ni interface after reflowing and thermal aging. Therefore, the electroplated Ni barrier layer in thermoelectric module should have large grain size to retard the growth rate of the intermetallic compounds.摘要 i Abstract ii 目次 iii 表目次 v 圖目次 vi 第一章、LCD驅動IC元件之剝離測試及界面反應分析 1 1.1 前言 1 1.2 文獻回顧 3 1.2.1 LCD驅動IC封裝 3 1.2.2 內引腳導線接合技術 4 1.2.3 ILB接點界面反應 6 1.3 實驗方法 9 1.4 結果與討論 12 1.5 結論 21 第二章、鎳擴散阻障層對不同結構熱電基材與無鉛銲料界面反應之影響 22 2.1 前言 22 2.2 文獻回顧 24 2.2.1 熱電材料之發展 24 2.2.2 Bi2Te3之材料特性 28 2.2.3 無鉛銲料與Bi2Te3之界面反應 33 2.2.4 應用於碲化鉍系熱電模組之阻障層材料 34 2.2.5 Sn-Ag-Cu-(Ni)/Ni界面反應 43 2.3 研究動機 45 2.3.1 塊材結構及奈米結構熱電材料 45 2.3.2 鍍Ni方式 45 2.4 實驗方法 46 2.4.1 基材製備及分析 46 2.4.2 電鍍Ni層 47 2.4.3 固固界面反應 49 2.5 結果與討論 51 2.5.1 基材結構及組成分析 51 2.5.2 SAC405/electroplated Ni/TE substrate 之界面反應分析 56 2.5.3 電鍍Ni層結構分析 60 2.5.4 SAC405 + 0.1-0.3 wt.% Ni/Ni箔之固固界面反應 67 2.5.5 SAC405/electroplated Ni/TE substrate 之界面反應機制 72 2.6 結論 73 第三章、參考文獻 74 附錄-期刊發表 84 附錄-研討會論文 8