本實驗主要探討銀粉改質對焊接界面的影響。在高溫焊接時，較容易出現滲銀現象(leaching)，此情況會導致焊接面失效，因此本實驗藉由披覆奈米二氧化矽至銀粉表面，焊接時，期望能透過披覆之奈米二氧化矽來改善滲銀現象。
利用Stöber方法，以TEOS作為前驅物，透過水解縮和反應將奈米二氧化矽披覆至銀粉表面。以FTIR以及SEM觀察不同TEOS添加量及不同反應時間之銀粉顯微結構，隨著反應時間的增長，奈米二氧化矽披覆至銀粉表面的量也增多。由TEM結果顯示奈米二氧化矽分佈在介金屬化合物(IMC)之晶界，因此焊接時，能夠阻擋無鉛焊錫擴散，使滲銀現象延後出現，並利用成長動力學分析IMC成長機制，實驗結果顯示，IMC成長主要屬於體擴散機制，且隨著奈米二氧化矽披覆量增加，IMC成長之活化能提高，而成長速率降低。1、3、5wt% TEOS添加量反應24小時之成長活化能分別為72、89、112(kJ/mol)，反應48小時之成長活化能分別為77、95、123(kJ/mol)

In this study, the effects of silver powder modification on the IMC formation, silver leaching during soldering at high temperatures were investigated. During high-temperature soldering, silver leaching easily occurs, which will lead to failure of the soldering joint. Therefore, in this study, the deposition of nano-silica onto silver powder surface was developed to inhibit silver leaching during soldering at high temperatures.
Nano-silica was deposited on the surface of the silver powder through hydrolysis and condensation reaction of TEOS based on the Stöber method. FTIR and SEM were used to observe the microstructures of silver powders after deposition of nano-silica with different TEOS additions and different deposition time. As the deposition time increased, the amount of nano-silica coated on the surface of the silver powder also increased. The TEM results show that nano-silica located at the grain boundary of the intermetallic compounds (IMCs), which can hinder the dissolution of IMC by the lead-free solder melt along grain boundary during soldering, and hence retarding the silver leaching. The growth kinetics of IMC during soldering was investigated and the growth mechanism of IMCs was also analyzed. The results show that the growth of IMCs is mainly dominated by the bulk diffusion. The activation energy for IMCs growth increased, and the growth rate decreased with increasing the nano-silica content and the deposition time.

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