The Experts below are selected from a list of 99 Experts worldwide ranked by ideXlab platform

Peter Ryser - One of the best experts on this subject based on the ideXlab platform.

  • Long-term mechanical reliability of ceramic Thick-Film Circuits and mechanical sensors under static load
    Sensors and Actuators A: Physical, 2012
    Co-Authors: Thomas Maeder, Caroline Jacq, Peter Ryser
    Abstract:

    In this work, we study the long-term mechanical strength under static load - i.e. static fatigue performance or resistance to subcritical crack growth - of ceramic Thick-Film Circuits, namely how the static fatigue of the substrate is affected by the presence of Thick-Film compositions on the surface subjected to tensile stress. Three substrate materials were compared: standard 96% alumina (Al2O3) and two grades of high-strength zirconia-toughened alumina (ZTA). The tested Thick-Film compositions included Ag- and Au-based conductors, a multilayer dielectric, resistors, and an overglaze, alone or in combination. The tests were carried out by applying a nominally constant load on cantilevers, at room temperature and in nominally 100% humidity, with stress data extracted according to log-normal and Weibull statistics. In the blank state, both ZTA grades exhibit higher short-term strength than 96% Al2O3, as well as much higher resistance to static fatigue. However, many Thick-Film compositions are found to degrade the static fatigue performance, with higher-strength ZTA being in general more affected. This implies that Thick-Film materials used in Circuits under high mechanical stress, such as force and pressure sensors and devices operating in harsh environments, must be carefully chosen and placed in order to ensure reliable long-term operation.

  • Long-Term Mechanical Reliability of Ceramic Thick-Film Circuits and Mechanical Sensors Under Static Load
    Procedia Engineering, 2011
    Co-Authors: Thomas Maeder, Caroline Jacq, Peter Ryser
    Abstract:

    Recently, high-strength zirconia-toughened alumina (ZTA) ceramic substrates have attracted interest, because they offer much improved mechanical properties over straight alumina, while maintaining advantages such as good thermal conductivity and chemical stability. This allows their application in high-power electronics and piezoresistive Thick-Film sensors, where the substrate is subjected to considerable stress. This work examines the impact of processing a range of Thick Film materials (Ag- and Au-based conductors, and a resistor material widely used in piezoresistive sensors) on the short- and long-term strength of ZTA, as compared to the standard 96% alumina used in Thick-Film electronics. It is found that many layers substantially reduce the substrate strength, especially in the long term, which is related to enhanced crack growth in the presence of glassy layers. These findings have pronounced implications in piezoresistive sensor design.

S. Leppävuori - One of the best experts on this subject based on the ideXlab platform.

  • Direct gravure printing (DGP) method for printing fine-line electrical Circuits on ceramics
    IEEE Transactions on Electronics Packaging Manufacturing, 2004
    Co-Authors: Marko Kittilä, Juha Hagberg, E. Jakku, S. Leppävuori
    Abstract:

    The tendency toward higher packing densities and higher frequencies for telecommunication devices based on ceramic technology requires smaller dimensions for electrical wiring. Electrical Thick-Film Circuits for ceramic and LTCC-substrates have, up to now, been printed with screen printing, where the printing lines width limit is about 125 /spl mu/m in mass production. A silicone polymer direct gravure printing (Si-DGP) process has been developed to perform smaller dimensions, down to 20 /spl mu/m lines width, for electrical circuitry. In the DGP process, the conductor paste is doctored to the grooves of the gravure and then it is pressed against the substrate. The paste is, thus, printed directly onto the substrate from the patterned gravure. The results showed that, using the DGP process, it was possible to print conductor lines down to 20 /spl mu/m in width. It was also noted that a 100% transfer of paste from the grooves of the gravure could be obtained with commercial pastes using the silicone polymer gravure. A dried Thickness of up to 28 /spl mu/m was measured for the narrowest lines. Also conductor lines printed by the Si-DGP method were embedded inside LTCC-module.

  • Fine line LTCC-structures by Direct Gravure Printing (DGP) method
    2002
    Co-Authors: Juha Hagberg, Marko Kittilä, E. Jakku, S. Leppävuori
    Abstract:

    Electrical Thick Film Circuits for ceramic and LTCC-substrates have, up to now, been printed mainly with screen printing. In conventional screen printing technology, the printing accuracy limit is about 150 μm in high volume production. By using advanced Thick Film technologies such as photo-imageable pastes, more accurate lines down to tens of μm can be produced. However, these processes are more complicated and costly compared to the direct printing processes. To overcome these limitations, a new printing process, Direct Gravure Printing (DGP), has been developed. In DGP the paste is printed directly onto the LTCC green sheet from a patterned gravure printing plate. The printing plates needed in the DGP processes are made by electro-depositing Nickel or moulding silicone polymer over a resist patterned flat plate. By using correct printing parameters, 100 % transfer of the printing paste from the gravure grooves to the substrate can be obtained. The printed line width can be down to at least 25 pm with good line and especially edge sharpness. In this paper the DGP process is introduced. To demonstrate the capability of it, a simple LTCC microwave test structure with transmission lines was designed, manufactured and measured. The design consisted of lines and gaps down to 20 μm wide. The attenuation ofa DGP processed 85 μm wide stripline was measured to be lower compared to a 185 pm wide screen printed one at frequencies below 14 GHz. At these frequencies, the conductor losses are the dominating ones, which indicates the high quality of the DGP printed transimission line.

  • gravure offset printing development for fine line Thick Film Circuits
    Microelectronics International, 2001
    Co-Authors: Juha Hagberg, S. Leppävuori, Marko Pudas, Ken Elsey, Alison Logan
    Abstract:

    The resolution of conventional graphical gravures is limited to about 50 to 100 microns depending on the technology used. For these gravures the depths are dependent on the widths of the grooves. For electrical circuitry, the target is to achieve 25 microns line and space widths in the near future. To obtain a reasonably high sheet resistance, the printed ink height must be reasonably high. The stated requirements require further development of the whole printing process together with the associated inks. The first step was to evaluate the gravure manufacturing method, which is capable of producing gravures of sufficient accuracy and uniform depth. In this paper a new gravure printing plate manufacturing method with high accuracy is presented. Printing results made with the manufactured gravure and tailored inks are reported.

  • Direct Gravure Printing (DGP) method for Printing fine line electrical Circuits
    2001
    Co-Authors: Juha Hagberg, Marko Kittilä, Marko Pudas, S. Leppävuori
    Abstract:

    The tendency towards higher packing densities and higher frequencies for telecommunication devices based on ceramic technology requires smaller dimensions for electrical wiring. Electrical Thick Film Circuits for ceramic and LTCC-substrates have, up to now, been printed with screen printing. This technology is well known and widely used in commercial production. In conventional screen printing technology, the printing accuracy limit is about 150 μm in high volume production. By using advanced Thick Film technologies such as photo-imageable pastes, more accurate lines down to tens of μm can be produced. However, these processes are more complicated and costly compared with direct printing processes. In this paper, a Direct Gravure Printing (DGP) process has been developed to make printed electrical circuitry more accurate. In DGP the paste is printed directly onto the substrate from a patterned gravure. The printing plate needed in the DGP process can be made by moulding or electro-depositing over a relief patterned flat plate. The relief patterns can be made by resist technology. The first results showed that, using the DGP process, it was possible to print conductor lines down to 25 μm wide. A dried Thickness of up to 30 μm was measured. The line height depended only slightly on the line width when elastic gravure material was used.

Juha Hagberg - One of the best experts on this subject based on the ideXlab platform.

  • Direct gravure printing (DGP) method for printing fine-line electrical Circuits on ceramics
    IEEE Transactions on Electronics Packaging Manufacturing, 2004
    Co-Authors: Marko Kittilä, Juha Hagberg, E. Jakku, S. Leppävuori
    Abstract:

    The tendency toward higher packing densities and higher frequencies for telecommunication devices based on ceramic technology requires smaller dimensions for electrical wiring. Electrical Thick-Film Circuits for ceramic and LTCC-substrates have, up to now, been printed with screen printing, where the printing lines width limit is about 125 /spl mu/m in mass production. A silicone polymer direct gravure printing (Si-DGP) process has been developed to perform smaller dimensions, down to 20 /spl mu/m lines width, for electrical circuitry. In the DGP process, the conductor paste is doctored to the grooves of the gravure and then it is pressed against the substrate. The paste is, thus, printed directly onto the substrate from the patterned gravure. The results showed that, using the DGP process, it was possible to print conductor lines down to 20 /spl mu/m in width. It was also noted that a 100% transfer of paste from the grooves of the gravure could be obtained with commercial pastes using the silicone polymer gravure. A dried Thickness of up to 28 /spl mu/m was measured for the narrowest lines. Also conductor lines printed by the Si-DGP method were embedded inside LTCC-module.

  • Fine line LTCC-structures by Direct Gravure Printing (DGP) method
    2002
    Co-Authors: Juha Hagberg, Marko Kittilä, E. Jakku, S. Leppävuori
    Abstract:

    Electrical Thick Film Circuits for ceramic and LTCC-substrates have, up to now, been printed mainly with screen printing. In conventional screen printing technology, the printing accuracy limit is about 150 μm in high volume production. By using advanced Thick Film technologies such as photo-imageable pastes, more accurate lines down to tens of μm can be produced. However, these processes are more complicated and costly compared to the direct printing processes. To overcome these limitations, a new printing process, Direct Gravure Printing (DGP), has been developed. In DGP the paste is printed directly onto the LTCC green sheet from a patterned gravure printing plate. The printing plates needed in the DGP processes are made by electro-depositing Nickel or moulding silicone polymer over a resist patterned flat plate. By using correct printing parameters, 100 % transfer of the printing paste from the gravure grooves to the substrate can be obtained. The printed line width can be down to at least 25 pm with good line and especially edge sharpness. In this paper the DGP process is introduced. To demonstrate the capability of it, a simple LTCC microwave test structure with transmission lines was designed, manufactured and measured. The design consisted of lines and gaps down to 20 μm wide. The attenuation ofa DGP processed 85 μm wide stripline was measured to be lower compared to a 185 pm wide screen printed one at frequencies below 14 GHz. At these frequencies, the conductor losses are the dominating ones, which indicates the high quality of the DGP printed transimission line.

  • gravure offset printing development for fine line Thick Film Circuits
    Microelectronics International, 2001
    Co-Authors: Juha Hagberg, S. Leppävuori, Marko Pudas, Ken Elsey, Alison Logan
    Abstract:

    The resolution of conventional graphical gravures is limited to about 50 to 100 microns depending on the technology used. For these gravures the depths are dependent on the widths of the grooves. For electrical circuitry, the target is to achieve 25 microns line and space widths in the near future. To obtain a reasonably high sheet resistance, the printed ink height must be reasonably high. The stated requirements require further development of the whole printing process together with the associated inks. The first step was to evaluate the gravure manufacturing method, which is capable of producing gravures of sufficient accuracy and uniform depth. In this paper a new gravure printing plate manufacturing method with high accuracy is presented. Printing results made with the manufactured gravure and tailored inks are reported.

  • Direct Gravure Printing (DGP) method for Printing fine line electrical Circuits
    2001
    Co-Authors: Juha Hagberg, Marko Kittilä, Marko Pudas, S. Leppävuori
    Abstract:

    The tendency towards higher packing densities and higher frequencies for telecommunication devices based on ceramic technology requires smaller dimensions for electrical wiring. Electrical Thick Film Circuits for ceramic and LTCC-substrates have, up to now, been printed with screen printing. This technology is well known and widely used in commercial production. In conventional screen printing technology, the printing accuracy limit is about 150 μm in high volume production. By using advanced Thick Film technologies such as photo-imageable pastes, more accurate lines down to tens of μm can be produced. However, these processes are more complicated and costly compared with direct printing processes. In this paper, a Direct Gravure Printing (DGP) process has been developed to make printed electrical circuitry more accurate. In DGP the paste is printed directly onto the substrate from a patterned gravure. The printing plate needed in the DGP process can be made by moulding or electro-depositing over a relief patterned flat plate. The relief patterns can be made by resist technology. The first results showed that, using the DGP process, it was possible to print conductor lines down to 25 μm wide. A dried Thickness of up to 30 μm was measured. The line height depended only slightly on the line width when elastic gravure material was used.

  • Method for manufacturing high-quality gravure plates for printing fine-line electrical Circuits
    Device and Process Technologies for MEMS and Microelectronics, 1999
    Co-Authors: Juha Hagberg, Seppo Leppaevuori
    Abstract:

    Electrical Thick Film Circuits have, up to now, been printed with screen printing. This technology and PCB-processing technology are well known and widely used in commercial production. In conventional screen printing and PCB- technology, the accuracy limit is at about 150 microns. The tendency towards higher packing densities requires smaller dimensions to be printed. THerefore, a gravure offset printing process for electronic circuitry is under development. One important task in printing process development is the requirement for high quality and accurate gravure plates. In conventional pad printing, etching, laser engraving and photopolymer methods are the processes mainly used for gravure plate making. For the production of high quality and accurate gravure plates, a new process has been developed. A grooved gravure plate is electrodoped on a substrate upon which a photoresist pattern has been formed. After electrodeposition, the plate is peeled from the substrate. There are several advantages over the existing process. The surfaces of the grooves so formed are smooth. The depth of the grooves can be accurately controlled because it is the same as the Thickness of the applied resist layer. Grooves deep enough to transfer sufficient ink needed for the electrical circuit patterns may be realized.

Thomas Maeder - One of the best experts on this subject based on the ideXlab platform.

  • Long-term mechanical reliability of ceramic Thick-Film Circuits and mechanical sensors under static load
    Sensors and Actuators A: Physical, 2012
    Co-Authors: Thomas Maeder, Caroline Jacq, Peter Ryser
    Abstract:

    In this work, we study the long-term mechanical strength under static load - i.e. static fatigue performance or resistance to subcritical crack growth - of ceramic Thick-Film Circuits, namely how the static fatigue of the substrate is affected by the presence of Thick-Film compositions on the surface subjected to tensile stress. Three substrate materials were compared: standard 96% alumina (Al2O3) and two grades of high-strength zirconia-toughened alumina (ZTA). The tested Thick-Film compositions included Ag- and Au-based conductors, a multilayer dielectric, resistors, and an overglaze, alone or in combination. The tests were carried out by applying a nominally constant load on cantilevers, at room temperature and in nominally 100% humidity, with stress data extracted according to log-normal and Weibull statistics. In the blank state, both ZTA grades exhibit higher short-term strength than 96% Al2O3, as well as much higher resistance to static fatigue. However, many Thick-Film compositions are found to degrade the static fatigue performance, with higher-strength ZTA being in general more affected. This implies that Thick-Film materials used in Circuits under high mechanical stress, such as force and pressure sensors and devices operating in harsh environments, must be carefully chosen and placed in order to ensure reliable long-term operation.

  • Long-Term Mechanical Reliability of Ceramic Thick-Film Circuits and Mechanical Sensors Under Static Load
    Procedia Engineering, 2011
    Co-Authors: Thomas Maeder, Caroline Jacq, Peter Ryser
    Abstract:

    Recently, high-strength zirconia-toughened alumina (ZTA) ceramic substrates have attracted interest, because they offer much improved mechanical properties over straight alumina, while maintaining advantages such as good thermal conductivity and chemical stability. This allows their application in high-power electronics and piezoresistive Thick-Film sensors, where the substrate is subjected to considerable stress. This work examines the impact of processing a range of Thick Film materials (Ag- and Au-based conductors, and a resistor material widely used in piezoresistive sensors) on the short- and long-term strength of ZTA, as compared to the standard 96% alumina used in Thick-Film electronics. It is found that many layers substantially reduce the substrate strength, especially in the long term, which is related to enhanced crack growth in the presence of glassy layers. These findings have pronounced implications in piezoresistive sensor design.

Caroline Jacq - One of the best experts on this subject based on the ideXlab platform.

  • Long-term mechanical reliability of ceramic Thick-Film Circuits and mechanical sensors under static load
    Sensors and Actuators A: Physical, 2012
    Co-Authors: Thomas Maeder, Caroline Jacq, Peter Ryser
    Abstract:

    In this work, we study the long-term mechanical strength under static load - i.e. static fatigue performance or resistance to subcritical crack growth - of ceramic Thick-Film Circuits, namely how the static fatigue of the substrate is affected by the presence of Thick-Film compositions on the surface subjected to tensile stress. Three substrate materials were compared: standard 96% alumina (Al2O3) and two grades of high-strength zirconia-toughened alumina (ZTA). The tested Thick-Film compositions included Ag- and Au-based conductors, a multilayer dielectric, resistors, and an overglaze, alone or in combination. The tests were carried out by applying a nominally constant load on cantilevers, at room temperature and in nominally 100% humidity, with stress data extracted according to log-normal and Weibull statistics. In the blank state, both ZTA grades exhibit higher short-term strength than 96% Al2O3, as well as much higher resistance to static fatigue. However, many Thick-Film compositions are found to degrade the static fatigue performance, with higher-strength ZTA being in general more affected. This implies that Thick-Film materials used in Circuits under high mechanical stress, such as force and pressure sensors and devices operating in harsh environments, must be carefully chosen and placed in order to ensure reliable long-term operation.

  • Long-Term Mechanical Reliability of Ceramic Thick-Film Circuits and Mechanical Sensors Under Static Load
    Procedia Engineering, 2011
    Co-Authors: Thomas Maeder, Caroline Jacq, Peter Ryser
    Abstract:

    Recently, high-strength zirconia-toughened alumina (ZTA) ceramic substrates have attracted interest, because they offer much improved mechanical properties over straight alumina, while maintaining advantages such as good thermal conductivity and chemical stability. This allows their application in high-power electronics and piezoresistive Thick-Film sensors, where the substrate is subjected to considerable stress. This work examines the impact of processing a range of Thick Film materials (Ag- and Au-based conductors, and a resistor material widely used in piezoresistive sensors) on the short- and long-term strength of ZTA, as compared to the standard 96% alumina used in Thick-Film electronics. It is found that many layers substantially reduce the substrate strength, especially in the long term, which is related to enhanced crack growth in the presence of glassy layers. These findings have pronounced implications in piezoresistive sensor design.