Processing and Characterization of La2O3/B2O3/Al2O3 Based Glass-Ceramic Composite for LTCC Application
Date Issued
2004
Date
2004
Author(s)
Chen, Chih-Lung
DOI
en-US
Abstract
本研究欲製備出不含鉛化物、不含鹼金屬離子、低介電損失、並可於低溫下燒結之氧化鑭（La2O3）、氧化鋁（Al2O3）及氧化硼（B2O3）成分之玻璃複合材料，簡稱為LAB玻璃複材，應用於微波介電陶瓷基板。其概念乃是源自於杜邦943刮帶所使用之低溫玻璃陶瓷系統，本研究採用LAB之三元成分，在1350oC，於空氣中熔融一小時，在製程窗及晶相相容區的結果中整合出適當的玻璃及陶瓷組成區域。多種成分的玻璃經由一系列的潤濕角量測、燒結潛變行為評估、燒結收縮測試及示差掃描熱量儀分析，其中L2玻璃（氧化鑭: 10 mol% 氧化鋁: 10 mol% 氧化硼: 80 mol%）添加氧化鋁填料最符合需求，並為LAB玻璃系統中最佳的初始成分。
L2玻璃添加30 mass%的氧化鋁（簡稱L30A）於800oC持溫一小時並於850oC作十分鐘的結晶處理可達完全緻密，整體的燒結流程設計亦已最佳化，微結構觀察中可發現等軸LaBO3及片狀LaAl2B3O9之結晶體，其燒結後之基地僅殘存有限的玻璃相。而LaAl2B3O9片狀晶生成於氧化鋁、LaBO3及玻璃之三相接合處，於870oC溫度以上，此結晶由氧化鋁之（00h）晶面呈放射狀明顯成長。
研究中並將L2純玻璃及L30A之玻璃陶瓷以非恆溫方式進行熱處理，著重於孕核現象之機制探討及晶體成長動力學之分析，以及各種相關微結構的觀察及相鑑定分析，其結果顯示，儘管LaBO3結晶於玻璃基底有均質成核的現象，但LaBO3結晶於氧化鋁界面上的異質成核仍是為主導機制。本研究並深入探討氧化鋁於結晶活化過程中，對於LaBO3結晶相生成之影響，分析LaBO3結晶體的相轉變過程，並建立出LaBO3結晶體及LaAl2B3O9片狀晶於燒結過程中的孕核及結晶行為模式。
本研究另一重要課題即是與LAB複材相關之微波介電性質及其與銀電極積層化共燒之特性分析。首先，積層之LAB/Ag複材於850oC下進行共燒，結果顯示於LAB/Ag界面處呈現良好的匹配性，發現L30A與銀電極間並無明顯之界面反應，再者，並在評估其不同頻率下之介電常數、介電損失、熱膨脹係數、熱傳係數及硼溶出測試之後，認為L30A玻璃陶瓷複材可符合微波通訊元件之應用。
A low firing-temperature, lead-free, non-alkali and low dielectric-loss La2O3-Al2O3-B2O3 (LAB) composites, which was originated from DuPont 943 tape system, has been developing and investigated as a LTCC for microwave applications. The processing window and compatibility fields of the LAB glasses were determined as the glass-ceramics melted at 1350oC for 1h in air. Several crystalline phases formed in different formulations after the melting test. The wetting, shape creeping, sinter-shrinkage, and DSC properties of the glasses were analyzed. L2 glass (La2O3: 10 mol% Al2O3: 10 mol% B2O3: 80 mol%) was selected as an optimal formulation to composite with Al2O3 filler for the property requirements.
The L2 glass with 30 mass% Al2O3 filler (L30A) can be fully densified at 800oC in 1 h and devitrified at 850oC for 10 min. The sintering scheme has been optimized to achieve limit dissolution of Al2O3 grain and crystallization of equi-axial LaBO3 and flaky LaAl2B3O9 crystals. The final matrix has limited glassy phase. The LaAl2B3O9 grains apparently grew above 870oC, generated at the triple junction of Al2O3, LaBO3 grains and glass boundaries, and extended radially from the (00h) crystalline planes of Al2O3 grains.
The crystallization kinetics of primary LaBO3 phase in the L2 glass and L30A were investigated. The results appeared that a heterogeneous nucleation on the Al2O3/glass is the dominating factor, although scattered LaBO3 crystals still can grow in the glass homogeneously. The activation process of the LaBO3 phase was analyzed in the glass and by the influence of Al2O3 phase. A crystallization model was proposed in this work.
Several critical properties related to the microwave and multilayer applications have been studied as well. Laminated LAB/Ag composite cofired at 850oC appeared no interfacial reactions. The interface depicted well bonding with Ag electrode layer. The dielectric constant (k), dielectric loss, coefficient of thermal expansion (CTE), acid-dissolving test, and thermal conductivity of the LAB/Al2O3 were determined and appeared appropriate quality for the microwave applications.
Subjects
氧化硼
LaAl2B3O9
LaBO3
玻璃陶瓷
低溫共燒陶瓷
氧化鑭
氧化鋁
潤濕
微結構
動力學
wetting
LTCC
microwave
La2O3
Al2O3
kinetics
glass-ceramic
B2O3
microstructure
Type
thesis
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