Sn-8Zn-(0~4)Bi中鉍含量對其迴銲於化金基板上後機械性質及電化學遷移之影響

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Title:	Sn-8Zn-(0~4)Bi中鉍含量對其迴銲於化金基板上後機械性質及電化學遷移之影響
Authors:	簡宏文;Hung-Wen Chien
Contributors:	機械工程研究所
Keywords:	微硬度試驗;熱處理;陽極動態極化分析;無鉛銲料;錫鋅鉍銲料;電化學遷移;推球試驗;Sn-Zn-Bi solder;electrochemical migration;heat treatment;anodic potentiodynamic polarization
Date:	2006-07-10
Issue Date:	2009-09-21 11:54:36 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本研究在比較添加0~4wt%Bi於Sn-8wt%Zn銲料，當其迴銲於化金基板後，機械性質的變化及其在水中電化學行為之差異。機械性質藉由微硬度及推球實驗得知：Sn-8Zn-(0~4)Bi無鉛銲料在迴銲前後機械性質質量變化不大，但微硬度(Hv)隨鉍含量增加而稍有增強，從15.96±0.57增強至29.96±0.16(Hv)；推球強度從6.54±0.31增加至8.31±0.1(N)。電化學研究結果顯示：當外加偏壓在3~5V下，Sn-8Zn-(0~4)Bi銲料在水中會有電化學遷移現象。電化學遷移程度可藉由量測短路電流所耗用之時間進行評估。在3V下銲料中鉍濃度由0增至4wt%時，其短路時間由202秒縮短到120秒。Sn-8Zn-4Bi銲料在偏壓由3增大至5V，短路時間也由120秒縮短至98秒。觀察分析兩極間遷移之產物得知：遷移反應以鋅之溶解、析出為主。Sn-8Zn-(0~4)Bi之微結構解析顯示；鋅的溶解與析出隨著銲料中鉍含量增加而更容易發生，因而導致加速其電化學遷移。EPMA之分析及陽極動態極化曲線之探討可以解釋此一電化學行為之根據。 Sn-8Zn-(0~4)Bi銲料於化金基板上250℃迴銲1分鐘後，再經150℃加熱0、600、1200秒後，顯示出其在水中電化學遷移短路時間之差異：未經熱處理之試片，短路時間為120秒，600秒熱處理後之試片其短路時間稍有延長為137秒。若延長熱處理時間至1200秒，則反而縮短短路時間至98秒。由EPMA解析熱處理前後銲料之微結構及其組成變化，以及陽極極化曲線之探討可以解釋其電化學遷移之機制。 The phenomenon of mechanical nature and electrochemical migration of Sn-8Zn-(0~4)Bi solders, reflowed on Au/Ni/Cu pads were studied in this paper. The results show that electrochemical migration happened when DC voltage(3~5V) was applied to the solders in water. It is assessed that Electrochemical migration behaviors can be measured in electric current service time. When the bismuth of the solder increased from 0wt% to 4wt% the short circuit time of 3V bias decreased from 202s to 120s. The short out time shrotenned with the voltage increased from 3 to 5V. Analysis of EPMA and XPS on the dendrite precipitate formed between two electrodes displays that the main component of the precipitate is Zn. The phenomenon of mechanical nature and electrochemical migration of Sn-8Zn-(0~4)Bi solders, having been reflowed on Au/Ni/Cu pads with 150℃ heat treatment for 0, 600, 1200s were discussed in this paper. It is assessed that Electrochemical migration behaviors shorted out at 1200s can be measured in electric current service time. Result of study：The short out time became 137s and 98s when the time of heat treatment were 600 and 1200s. When the heat treatment time is longer than 1200s, heat treatment will accelerate electrochemical migration. Analysis of EPMA and XPS on the dendrite precipitate formed between two electrodes displays that the main component of the precipitate is Zn.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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