本研究的主旨在於開發YAG:Ce螢光陶瓷板，期望未來能採用此一陶瓷材料，直接貼合LED晶片或是固定於晶片上方的新型封裝技術，來減少樹脂的使用量，取代目前白光LED利用樹脂封裝的方式，進一步增加LED之散熱效率，延長其使用壽命。

而本研究首先以膠體共沉法Y2.94Al5O12:Ce0.06與固態反應法Y2.95Al5O12:Ce0.05作為各起始粉末之劑量比，並於製程中摻雜不同重量比之SiO2後，對粉體進行壓胚與燒結。研究結果顯示，摻雜適當比例SiO2之YAG:Ce生胚，經熱處理後，YAG相可與SiO2產生共晶反應，因此製程上於較低溫度時，即可發生液相燒結的情形，增加樣品內部之緻密性，有助Ce3+稀土離子的擴散，提升YAG:Ce螢光陶瓷板之發光效率。

另一方面，本研究也試著改善各製程，如將共沉法製作之樣品進行重覆燒結，以及於固態法製程中探討SiO2在製程中添加的時機點等，對於YAG:Ce螢光陶瓷板之發光性質，都有一定的提升效果。

在熱傳導研究結果方面，發現確實在添加適當比例之SiO2以後，由於YAG:Ce螢光陶瓷板內部孔洞減少與結晶性增加的關係，熱傳導係數有增加的趨勢。此外對於熱消淬性質而言，由於添加SiO2以後，YAG:Ce螢光陶瓷板之熱消淬活化能變大的關係，因此在熱穩定性上也有所提升。

而在比較不同壓胚方式上，冷均壓雖然可以使YAG:Ce螢光陶瓷板更緻密，但推測由於螢光陶瓷板內部結晶性降低，所以導致在發光效率上，反而不如單軸加壓之結果。

而本研究最後也將YAG:Ce螢光陶瓷板與藍光晶片做初步的簡易接合光學測試，發現摻雜5wt% SiO2之YAG:Ce螢光陶瓷板，其整體LED流明效率約為未摻雜SiO2之樣品的六倍之多，因此摻雜SiO2之YAG:Ce螢光陶瓷板在未來應用上是相當具有潛力的。

This study is to fabricate the YAG:Ce phosphor ceramic used for the new LED packaging technology. In order to reduce the usage of resin in LED, the phosphor ceramic of YAG:Ce was utilized to be attached to the chips directly or be fixed around the chips. This method can substitute for the current white LED packaging technique with resin encapsulation and prolong the lifetime of LED by improving the ability of heat dissipation.
At first, the YAG:Ce phosphors with stoichiometric Y2.94Al5O12:Ce0.06 and Y2.95Al5O12:Ce0.05 are prepared by co-precipitation method and solid state reaction, respectively. Then, the YAG:Ce phosphors with the addition of different amounts of SiO2 are pressed and sintered. The eutectic reaction of YAG and SiO2 is found by doping appropriate proportion SiO2 after heat treatment. The liquid phase which resulted in densification of the phosphor ceramic is observed even by sintering at lower temperature. It is also benefit for the diffusion of Ce3+ ion in the YAG phosphors and enhancement of the luminous intensity of YAG:Ce phosphor ceramics.
On the other hand, the study uses different method to fabricate the phosphor ceramic, such as multiple sintering for the samples by co-precipitation method and the different ways of doping SiO2 in the samples by solid state reaction. The optical property of YAG:Ce phosphor ceramics both can get improvement .
In the thermal conductivity results, after doping the appropriate proportion of SiO2, owing to reduce the number of internal holes in the YAG:Ce phosphor ceramic and have the better crystallinity, the thermal conductivity can get increase. In addition, for the thermal quenching property, because the activation energy for thermal quenching of YAG:Ce phosphor ceramic increase by SiO2 addition, the thermal stability is also improved. In comparison with different pressing process, though it can lead to the YAG:Ce phosphor ceramic more compact by the cold isostatic pressing, it would reduce the crystallinity of YAG:Ce phosphor ceramic. Resulting in luminous efficiency, it is not as good as the uniaxial pressing. Finally, the YAG:Ce phosphor ceramics are mounted on the blue LED chips to investigate some optical properties. Finding that the luminous efficacy of YAG:Ce phosphor ceramics with doping 5wt% SiO2 are six times as much as without doping SiO2. Therefore, YAG:Ce phosphor ceramic with doping SiO2 is absolutely potential for future applications.

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