無助焊劑下錫鎳與錫銅合金在鎳金與鎳鈀金上之濕潤行為研究

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Title:	無助焊劑下錫鎳與錫銅合金在鎳金與鎳鈀金上之濕潤行為研究
Authors:	莊玟寧;Chuang,Wen-Ning
Contributors:	化學工程與材料工程學系
Keywords:	焊料;錫鎳;錫銅;鎳金;鎳鈀金;濕潤性;solder;SnNi;SnCu;ENIG;ENEPIG;wettability
Date:	2014-06-20
Issue Date:	2014-08-11 18:14:08 (UTC+8)
Publisher:	國立中央大學
Abstract:	由於助焊劑可以有效移除液態焊料表面的氧化層，並確保在迴焊過程中達到好的濕潤性，因此，助焊劑廣泛用於電子封裝。然而，迴焊過程添加的助焊劑會有殘留的問題，殘留的助焊劑會汙染電子元件晶片，導致壽命減短。由此可見，在電子封裝工業領域，發展不添加助焊劑的迴焊技術是個重要的議題。本實驗在不使用助焊劑下，實驗溫度為330℃，選用不同成分銅、鎳添加的四種錫銅與錫鎳焊料，Sn0.2wt.%Cu、Sn0.7 wt.%Cu、Sn1.2 wt.%Cu、Sn2 wt.%Cu及Sn0.2 wt.%Ni、Sn0.7 wt.%Ni、Sn1.2 wt.%Ni、Sn2 wt.%Ni，於還原氣體的氣氛下，分別迴焊於鎳鈀金(ENEPIG)以及鎳金(ENIG)基板上，進行迴焊30秒。我們從微結構分析上，發現迴焊過程中焊料內部析出的介金屬化合物(IMC)愈多則濕潤性愈差。錫鎳焊料迴焊於鎳鈀金基板上的濕潤性較迴焊於鎳金基板上良好，因為鈀原子從鎳鈀金基板溶入錫鎳焊料中，鈀原子會與鎳原子在焊料與基板的介面形成一穩定相-(Ni, Pd)3Sn4 ，因此，錫鎳焊料中存在較少鎳原子可在焊料內部IMC。除此之外，我們也發現錫銅焊料迴焊於鎳金基板上的濕潤性較迴焊於鎳鈀金基板上良好，因為鈀原子從鎳鈀金基板溶入錫銅焊料中，鈀原子會與銅原子反應，將銅原子抓入焊料中，集中於焊料兩側生成大量(Cu, Ni, Pd)6Sn5，而焊料與基板介面擁有較少的銅原子可形成IMC。綜合以上，我們得知IMC析出於焊料當中會影響其濕潤性，從過去文獻中也可佐證，這是由於愈多IMC析出於焊料當中，焊料的黏度會提高，表面張力也隨之變大，並產生一內聚力於焊料當中，導致焊料的濕潤性表現較差。 ;The flux has been widely used for soldering in the electronic package, since the flux can effectively remove the oxidation layer of the molten solder and ensure a good wetting during the reflow process. However, after the reflow process, the residual flux will cause the life-time degradation of the solder joints. Therefore, developing the fluxlessreflow process is an important issue for the IC package industry. In this study, without using flux, the Sn-based solders (SnCu, SnNi) were reflowed on the PCB with ENIG (Cu/Ni(P)/Au) and ENEPIG(Cu/Ni(P)/Pd/Au).We found that all solders show reasonably good wetting on the ENIG and ENEPIG substrate at relatively high temperature, above 330 C. The surface area become wider during wetting. At this moment, the surface energy increase and very unstable. For reach a stable status, Solder by changing the structure of surface or surface segregation to reduce the surface energy. We can observe that many solid segregated in solder. Therefore, we believe that solder by segregating compound in solder to reduce surface energy. For these results, Compounds precipitated in solder matrix during wetting caused viscosity of solder increase; at the same time, surface tension increase. Higher surface tension of solder will generate higher cohesion of molten solder, leading to poor wettability. Therefore, compound in solder matrix cause poor wettability during wetting.
Appears in Collections:	[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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