Mingsheng Ma

Thermal performance of high power LED package based on LTCC

A novel 3D model of LTCC based high power LED package which reduced the package thermal resistance is established. It has quite low junction temperature and thermal resistance Rj-b is only 2.42°C/W. The analysis results reveal that the effect of copper volume and distribution in LTCC board plays a critical role in the heat dissipation of the LED package. Horizontal heat dissipation is also very important except for vertical thermal via. This work demonstrated that High performance LED package based on LTCC substrate can be obtained by optimizing the metallization structure of LTCC substrate or improve the thermal conductivity of LTCC material.

Passive wireless gas sensors based on the LTCC technique

Many of the existing gas sensors cannot offer long-term continuous performance, rendering them selected ineffective for environmental and point-of-care monitoring tasks. The problem may arise from the limitation in accessible power supplies for their operation and signal communications. As a solution, a wireless passive gas sensor based on low temperature co-fired ceramic (LTCC) technology is presented in this work. The sensor consists of a planar inductor-interdigital capacitor resonant antenna circuit, covered with gas sensitive coatings. The antenna together with this pair of interdigital electrodes was fabricated using the LTCC process. Gas sensitive films were made of two dimensional tin disulfide (SnS2) nanostructures, which were deposited on the interdigital electrodes by drop-casting method. The gas sensing performance was investigated by monitoring the impedance phase angle changes of the antenna in response to different gas types and concentrations.

Fabrications and Performance of Wireless LC Pressure Sensors through LTCC Technology

This paper presents a kind of passive wireless pressure sensor comprised of a planar spiral inductor and a cavity parallel plate capacitor fabricated through low-temperature co-fired ceramic (LTCC) technology. The LTCC material with a low Young’s modulus of ~65 GPa prepared by our laboratory was used to obtain high sensitivity. A three-step lamination process was applied to construct a high quality cavity structure without using any sacrificial materials. The effects of the thickness of the sensing membranes on the sensitivity and detection range of the pressure sensors were investigated. The sensor with a 148 μm sensing membrane showed the highest sensitivity of 3.76 kHz/kPa, and the sensor with a 432 μm sensing membrane presented a high detection limit of 2660 kPa. The tunable sensitivity and detection limit of the wireless pressure sensors can meet the requirements of different scenes.

Multilayer Metallized Ceramic Composites: LTCC Processing and Thermal Simulation

Thermal performance of metallized low temperature co-fired ceramic (LTCC) composites was investigated in this paper. Seven metallized LTCC composites with different structures were designed and fabricated by traditional LTCC process. The thermal conductivity of the metallized LTCC composites with thermal vias was enhanced by inserting parallel silver layers within the composites. The thermal performance of high power LED package based on the metallized LTCC composite substrates was simulated by finite element analysis method. The results demonstrated that horizontal heat dissipation was very important except for vertical thermal vias in the LTCC substrate.

Ka-Band LTCC Stacked Substrate Integrated Waveguide Bandpass Filter

A Ka-band substrate integrated waveguide bandpass filter has been designed and fabricated using low temperature co-fired ceramic (LTCC) technology. The in-house developed SICCAS-K5F3 material with a permittivity of 6.2 and a loss tangent of 0.002 was used. The size and surface area of the proposed bandpass filter are reduced by exploiting vertical coupling in vertically laminated three-dimensional structures. The coupling between adjacent cavities is realized by a narrow slot. A vertical transition structure between the coplanar-waveguide feed line and the substrate integrated waveguide is adopted to facilitate the internal signal connection. The demonstrated third-order filter has a compact size of 6.79 mm×4.13 mm×1.34 mm (0.63λ0  × 0.38λ0  × 0.12λ0) and exhibits good performance with a low insertion loss of 1.74 dB at 27.73 GHz and a 3 dB fractional bandwidth of 10 %.