Preparation of a CaO–Al2O3–B2O3–SiO2 glass/Al2O3 LTCC substrate material with high flexural strength for microwave application

Preparation of Sol–Gel-Derived CaO-B2O3-SiO2 Glass/Al2O3 Composites with High Flexural Strength and Low Dielectric Constant for LTCC Application

“…The XRD result of the CBS glass sheet only shows an amorphous phase, which is consistent with the DSC analysis of CBS glass. Meanwhile, the CBS glass/Al 2 O 3 composite sintered at 870 • C was also prepared, and the composite's XRD pattern (Figure 3) demonstrates that it is composed of a corundum phase and an amorphous phase [2]. Therefore, the XRD results of CBS glass and the CBS glass/Al 2 O 3 composite suggest that CBS glass does not crystallize due to being below the crystallization temperature and does not react with Al The surface and section morphologies of CBS glass/Al2O3 composites at different sintering temperatures were researched using a scanning electron microscope (SEM), as shown in Figure 4 and Figure 5, respectively.…”

“…Therefore, corundum, CBS glass, and some pores seen in SEM images exist in our CBS glass/Al 2 O 3 composite simultaneously. Then, we tested the dielectric constant of the CBS glass sheet sintered at 870 • C for 2 h, which is 3.6 (10 GHz), while the dielectric constants of Al 2 O 3 and air are 9.8 and 1, respectively [2,32]. However, it is reported that the dielectric constant of anorthite is 4.6 [33], which is higher than that of our CBS glass; therefore, our CBS glass/Al 2 O 3 composites without anorthite phase can achieve a lower dielectric constant of 6~6.3 (10 GHz) compared with other CBS glass/Al 2 O 3 composites reported.…”

“…The rapid progress in microwave communication technology requires miniaturized and multi-functional integrated electronic components [1,2]. Nowadays, low-temperature co-fired ceramics (LTCCs) are being used in the electronic package field due to their excellent microwave dielectric, mechanical, and thermal performance; they are an important solution for designing multilayer electronic devices [3][4][5][6].…”

“…Moreover, microelectronic packaging materials with a low dielectric constant and low dielectric loss can minimize capacitive coupling effects, leading to a reduced signal transmission delay time and effective signal attenuation [8]. In addition, as electronic devices are gradually integrated and minified, packaging substrates need to have more holes and wiring layouts per unit area, which requires high mechanical strength of the substrate materials [2]. Therefore, LTCC packaging materials need to possess lower dielectric constant/loss and increased mechanical strength for better packaging integrated and minified electronic devices, which has been an imperative subject recently.…”

“…Generally, the type and content of borosilicate glasses effectively influence the sintering characteristics and phase compositions of composites. Moreover, the flexural strength of glass/Al 2 O 3 composites is related to the densification level and crystalline phases, which are determined by sintering conditions and materials' properties [2]. Commonly, appropriate sintering temperature and time can improve the wettability of liquid glass and avoid the over-burning phenomenon; therefore, glass/Al 2 O 3 composites can form dense structures with reduced pores in them.…”