Chosen electrical, noise and stability characteristics of passive components embedded in printed circuit boards (original) (raw)

Analysis of long-term stability of capacitors embedded in printed circuit boards

Proceedings of the 2014 37th International Spring Seminar on Electronics Technology, 2014

This paper presents studies of long-term stability of capacitors embedded in printed circuit boards. Planar capacitors fabricated from FaradFlex dielectric foil with copper plates laminated to FR-4 substrate served as test structures. The dielectric was BaTiO 3 ceramic/polymer composition with various fillers and consequently various dielectric constants. Moreover test samples differed in composition thickness and surface size. The investigated capacitors were covered with LDP 2×106 (Laser Drillable Prepreg) protective layers to achieve embedded structures. The behaviour of capacitance as well as dissipation factor was investigated for two values of frequency (1 and 10 kHz) in order to determine their long-term stability. The in-situ accelerated ageing process (capacitance and dissipation factor of test samples performed directly at the ageing conditions) was carried out to perform long-term behaviour analysis. Temperature characteristics both before and after aging process were performed for determination of influence of environmental exposure. Additionally insulation resistance under voltage and temperature stress was monitored and analyzed.

DC and AC electrical properties and long-term stability of LTCC resistors

There is an interesting problem to become familiar with mutual dependencies between various DC and AC electrical properties as well as with correlation between electrical characteristics and long-term stability of electronic components. This paper presents wide and systematic investigations of electrical and stability properties of buried and surface Low Temperature Co-fired Ceramics (LTCC) resistors. Various resistors were made from commercially available 100 kΩ/sq. resistive ink on/in three different LTCC tapes (from various manufacturers). The influence of resistor/tape combinations (kind of LTCC green tapes, position of resistors) as well as resistor aspect ratio on sheet resistance, temperature dependence of resistance in a wide temperature range, low frequency noise, voltage nonlinearity, AC impedance spectra and long-term stability of thermally aged resistors were measured, analysed and discussed. Many interesting relations were found. For example it was proved, that LTCC resistors (made from the same resistive ink but in different technological variants) with significant dimensional effect were characterised by larger 1/f noise and larger nonlinearity. But dimensional effect did not affect AC properties and long term stability of such resistors.

Low-temperature properties of capacitors embedded into Printed Circuit Boards

2015 38th International Spring Seminar on Electronics Technology (ISSE), 2015

This paper presents low-temperature properties of capacitors embedded in Printed Circuit Boards. Planar capacitors, differed in composition thickness and surface size, were fabricated from FaradFlex dielectric foil with copper plates laminated to FR-4 substrate. The dielectric tapes were polymer or BaTiO 3 /polymer compositions with various dielectric constants. The investigated capacitors were covered with LDP 2×106 (Laser Drillable Prepreg) protective layers to achieve embedded structures. The temperature dependences of capacitance as well as dissipation factor (i.e. C(T) and tgδ(T) characteristics) were investigated for two values of frequency (1 and 10 kHz) in a wide temperature range-between-180C and room temperature. Moreover durability of capacitors to low-temperature thermal shocks (between liquid nitrogen and room temperature) are reported and analyzed.

Noise Spectroscopy of Resistive Components at Elevated Temperature

Metrology and Measurement Systems, 2014

Studies of electrical properties, including noise properties, of thick-film resistors prepared from various resistive and conductive materials on LTCC substrates have been described. Experiments have been carried out in the temperature range from 300 K up to 650 K using two methods, i.e. measuring (i) spectra of voltage fluctuations observed on the studied samples and (ii) the current noise index by a standard meter, both at constant temperature and during a temperature sweep with a slow rate. The 1/f noise component caused by resistance fluctuations occurred to be dominant in the entire range of temperature. The dependence of the noise intensity on temperature revealed that a temperature change from 300 K to 650 K causes a rise in magnitude of the noise intensity approximately one order of magnitude. Using the experimental data, the parameters describing noise properties of the used materials have been calculated and compared to the properties of other previously studied thick-film materials.

Electrical properties of dielectric foil for embedded PCB capacitors

Materials Science-Poland, 2012

One of the methods of achieving high packaging density of passive elements on the PCB is using the capacitors embedded in multilayer PCB. Test structures consisting of embedded capacitors were fabricated using the FaradFlex® capacitive internal layers. Impedance spectroscopy and equivalent circuit modelling was used to determine their electrical properties such as the capacitance, parasitic resistance and inductance. The use of several stages of accelerated ageing allowed us to test the durability of the structures. The results showed good quality stability of the embedded elements. The spatial distribution of the capacitance of the test structures on the surface of the PCB form was tested. The influence of the process parameters during lamination on the values of embedded capacitors was revealed.

Environmental conditions influence on embedded capacitors - Comparison with discrete capacitors

2010

The technology evolution of capacitors from a precedent paper in 1993 in which we studied a ceramic capacitor reported on a FR4 substrate to today's is very important. In order to reduce the risk of early failures peculiar to ceramic capacitors, technologists are using new polymer-ceramic materials embedded in the FR4 or FLEX substrate during the manufacturing step. In this paper the robustness of such embedded capacitors regarding the environmental conditions (temperature and humidity) was studied and compared to discrete ceramic capacitors.

Structure and properties of resistors and capacitors embedded into printed circuit board

The integration of electronic components with Printed Circuit Board (PCB) is now one of the main directions of electronic technology development. Until now many materials that can be used for embedded passives were created. But this technology is used mostly in military applications as well as in aviation and space electronics. Due to the growing number of passives that are now statistically required for proper operation of single integrated circuit, passive components become quickly a serious obstacle in miniaturization of electronic circuits and systems. Embedding of passive components into Printed Circuit Board allows further miniaturization and can lead to cost reduction. M oreover embedded passives are characterized by smaller parasitic effects. In this paper the results of material and electrical investigations of thin-and polymer thick-film resistors and planar capacitors embedded into PCBs are presented. The roughness investigations of laminates and each layer of the structure and the phase structure of used dielectric, resistive and conductive films are discussed. The cross-sections of the embedded structure obtained by scanning electron and optical microscopy are shown and discussed. The functional models contained embedded components and preliminary research of multicontact resistors is presented.

Steady-state and transient thermal properties of resistors embedded in printed circuit boards

This work presents experimental results of static and transient thermal characterisation of thin-film resistors embedded in printed circuit boards and commercial discrete resistors. Objects of study were differ in sheet resistance, size or topology. Temperature on the test sample surface was determined based on thermographic measurement. Based on experimental results maximal surface temperature was found. Moreover thermal time constant was evaluated which can be helpful to determine how quickly temperature is getting at equilibrium state. Conclusions of this work can be helpful to define thermal behaviour and maximum power dissipation of the resistors embedded in printed circuit boards.

On the temperature dependent dielectric

In this study, the temperature dependence of the dielectric properties, conductivity and resistivity of metal-insulator-semiconductor (MIS) structures have been investigated using capacitance (C) and conductance (G/x) measurements in wide temperature range of 120-400 K at 1 MHz. Calculation of the dielectric constant (e 0 ), dielectric loss (e 00 ), loss tangent (tan d), ac conductivity (r ac ), ac resistivity (q ac ) and the real and imaginary parts of electric modulus (M 0 and M 00 ) were given in the studied temperature range. The values of the e 0 , e 00 and r ac increase exponentially with the increasing temperature between 280 K and 400 K. On the other hand, these values remain almost constant between 120 K and 240 K. In addition, the experimental dielectric data have been analyzed by considering electric modulus formalism.