Tomasz Zawada

Laser treatment of LTCC for 3D structures and elements fabrication

This paper presents possibility of laser application for fabrication of 3D elements and structures. The Aurel NAVS‐30 Laser Trimming and Cutting System with special software was used. It was applied successfully for fabrication of vias (minimum diameter – 50u2009μm) in fired and unfired LTCC ceramics and channels with width between 100u2009μm and 5u2009mm. The achievements and problems are presented and discussed. The influence of lamination process on quality of vias and channels as well as the problems connected with interaction of laser beam with ceramic tapes are shown. Three‐dimensional resistors and microfluidic system were successfully designed and fabricated based on our investigations. Chosen electrical and thermal parameters of constructed devices are shown, too.

Properties of PZT thick films made on LTCC

Purpose – To find properties of screen printed PZT (PbZr0.53Ti0.47O3 with 6 per cent of PbO and 2 per cent of Pb5Ge3O11) thick films layers on LTCC substrate.Design/methodology/approach – The influence of PZT firing time and electrode materials on electrical characteristics and microstructure were examined. A scanning electron microscope (SEM) equipped with an energy‐dispersive X‐ray (EDS) analyser was used for the microstructural and compositional analysis.Findings – Microstructural and compositional analyses have shown the diffusion of SiO2 from LTCC into PZT layers and the diffusion of PbO in the opposite direction. SiO2 presumably forms low permitivity lead based silicates in PZT layer. The new phase deteriorates the piezoelectric properties. The amount of diffused materials was dependent upon the electrode material and increased with increasing firing time. Better properties, i.e. higher remanent polarisation and dielectric constant were achieved for samples with PdAg electrodes and shorter firing ti...

Simultaneous estimation of heat transfer coefficient and thermal conductivity with application to microelectronic materials

Abstract An estimation of unknown properties of materials arises naturally when one considers some aspects of thermal modeling, especially carried out by widely used numerical methods, e.g. Finite Element Method (FEM). We propose a new approach of simultaneous thermal conductivity and heat transfer coefficient estimation based on thermographic measurements. A linear, steady-state distributed parameter model is used in order to describe the test sample. Thermal properties measurement is equivalent to the unknown parameter estimation of this system. The proposed method is practically applied for estimation of thermal conductivity and heat transfer coefficient of thick-film modules made on alumina (96% Al 2 O 3 ) and DP951 ceramic substrates. In these experiments a high-resolution thermographic scanner is used. The obtained results for thermal conductivity and heat transfer factor are fully comparable with previously published ones.

LTCC package for MEMS device

LTCC package of silicon membrane katharometer was made and investigated. The package protects the katharometer against mechanical damage and makes possible an easy connection of electrical signals. Moreover, the heater and temperature sensors allow for obtaining the proper temperature of the element. The basic electrical parameters of the integrated heater and thermistors as well as measured temperature distribution are presented.

Fluidic micromixer made in LTCC technology - preliminary results

A specialized mixing structure incorporating LTCC (Low Temperature Cofired Ceramic) technology was designed and fabricated. Such structures can be applied in a wide range of chemical and biological microsystems. In order to achieve the best fluid mixing efficiency, few different geometries were tested and evaluated. Solutions of phenolphthalein and sodium hydroxide in ethyl alcohol were used in the performed experiments. A customized method of evaluation was proposed and successfully applied. In general, mixing performance varied with shape and dimensions of the mixing structure. The mixing channel technology, evaluation experiment as well as obtained results are presented in this article.

LTCC based microfluidic optical detector

A new fiber-based optical microfluidic detector was designed for low-volume sample measurement. Microdetector was fabricated by use of LTCC (low temperature co-fired ceramic) technology. The microdevice was made as separate module, which can be connected via tubing to any microanalytical system. The designed detector allowed to measure an optical absorbance (transmittance) in the analytical channel. Presented microfluidic detector can be also applied as a part of integrated muTAS (micro-total analysis system). The preliminary tests indicate linear absorbance detection in the range 9.5-28.5 mug/ml of cochineal red A and 10-20 mug/ml of sunset yellow in the test solutions

Three-dimensional fluidic microsystem fabricated in Low Temperature Cofired Ceramic Technology

A three-dimensional (3D) Low Temperature Cofired Ceramics (LTCC) fluidic microsystem integrated with an optical detection unit is presented in this article. The structure is applied to quantitative analysis of chemical compounds using colorimetric methods. The fabricated microfluidic system consists of a serpentine mixer, fluidic channels, heater, embedded temperature sensor and integrated optical fibers for detection of light transmission and/or fluorescence. A new inexpensive material for the embedded temperature sensor is described. The fluidic system is designed using computer CFD (Computational Fluid Dynamics) simulations. Fluid flow in the mixer is observed through a transparent polymer material bonded to the LTCC structure. The importance of positioning of optical fibers and their influence on the absorbance and fluorescence measurements is presented.

LTCC liquid conductivity detector

The design, technology and basic characteristics of the LTCC conductivity detector are presented. The finite element analysis (Ansys program) was applied to calculate the influence of the detector and electrodes geometry on the electrical properties. The electric potential and current density distributions inside the detector channel were analysed. The detector design was carried out on the base of ANSYS simulation. The detector was fabricated in typical LTCC process. YAG laser system was used for electrode fine line patterning and shaping the channels. The detector was tested by measurements of KCl solution with various concentration.

LTCC/PZT accelerometer in SMD package

Purpose – The purpose of this paper is to develop the device made of low temperature co-fired ceramics (LTCC) and lead zirconate titanate (PZT) by co-firing both materials. In the paper, the technology and properties of a miniature uniaxial ceramic accelerometer are presented. Design/methodology/approach – Finite element method (FEM) is applied to predict properties of the sensor vs main dimensions of the sensor. The LTCC process is applied during manufacturing of the device. All the advantages of the technology are taken into account during designing three-dimensional structure of the sensor. The sensitivity and resonant frequency of the accelerometer are measured. Real material parameters of PZT are estimated according to measurement results and FEM simulations. Findings – The ceramic sensor integrated with SMD package with outer dimensions of 5 × 5 × 5 mm3 is manufactured. The accelerometer exhibits sensitivity of 0.75 pC/g measured at 100 Hz. The resonant frequency is equal to about 2 kHz. Useful freq...

Transient modelling of temperature field in planar and 3D microvolume LTCC and thick-film resistors

Transient simulations of planar and 3D microvolume resistors on/in alumina and LTCC substrates are presented in the paper. The first test sample had five planar resistors with effective dimensions from 50/spl times/200 /spl mu/m/sup 2/ to 800/spl times/200 /spl mu/m/sup 2/ placed on/in 9.5/spl times/4.0 mm/sup 2/ substrate chip. The second one consisted of single 3D resistor with diameter from 100 to 500 /spl mu/m placed in 5/spl times/5 mm/sup 2/ alumina or LTCC substrates with 150 to 635 /spl mu/m thickness (resistor length). Simulations were performed for maximal microresistors temperature of about 160/spl deg/C. Well-known ANSYS finite element method software was used. Proper boundary conditions guaranteed physically acceptable distributions of temperature in simulated microcomponents. The first 40 seconds were simulated starting from the point when the power is applied to the microresistor. Examples of calculated temperature fields and their analyses are shown in the paper. Meaning of such distributions on reliability and stability is discussed, as well. Moreover, a simple model of thermal wave propagation in considered microstructures is presented.