- Email: [email protected]
Si-SiC material and SiC fiber-reinforced Si-SiC composites
PATENTS
Patents Force sensing apparatus Applicant: ASM Technology Ltd, Singapore The invention relates to force sensing apparatus for monitoring the bond force in an ultrasonic welding machine. Ultrasonic welding is commonly used for wire bonding when packaging semiconductor devices and for other bonding operations. Force sensors are used in the ultrasonic wire bonding machines to either monitor the quality of the wire bond by measuring the bond force, or to generate the required bond force in response to signals from the sensor. In some arrangements the force sensor is located in a structure which is external and isolated from the transducer. In other designs, the force sensor is mounted on the transducer body itself. Sensors residing on the body of the ultrasonic transducer are normally of the balanced strain gauge design. They measure the surface strains produced by bending the transducer during bonding and thus indirectly obtain information regarding the bond force. However, as they contact the transducer body they exert a load on the transducer, which interferes with the operation of the transducer. Force sensors located in force arms external to the bond-head are, in general, not compact. In general, piezoelectric force sensors and electrorestrictive force sensors suffer from the problem of output voltage drift. This introduces errors in successive measurements. To overcome this problem, a number of machines use two or more sensors to mutually compensate for any drift. However, this has the disadvantage of increasing cost and size of the arrangement and increases the processing required for the sensor signals. In this invention force sensing apparatus is provided for sensing deflection of a transducer in an ultrasonic welding machine. The apparatus includes a body member, a transducer holder and a force sensor. The transducer holder is adapted to hold an ultrasonic transducer and the transducer holder is fixed to the body member. The force sensor is located between adjacent surfaces of the body member and transducer holder to sense a force applied between surfaces. Patent number: US 6425514 Publication date: 30 July 2002 Inventors: Gang Ou, Gary Peter Widdowson, Ka Shing Kenny Kwan
Attachment method for piezoelectric elements Applicant: S. C. Johnson & Son Inc, USA
October 2002
The distribution of liquids by formation of a fine spray, or atomisation, is well known. One method for such distribution is to atomize a liquid by means of the acoustic vibration generated by an ultrasonic piezoelectric vibrator. Atomisers and/or dispensers fail to provide a system by which liquid to be dispersed is supplied to the vibratory mechanism/surface without resulting in corrosion, solvent activity by the active liquid, or bond failure at the point of joining of the piezoelectric element and the orifice plate, particularly when the active liquids are such as perfumes or insecticides, having high activity quotients at high rates of vibration. Moreover, the prior art has failed to provide an easily portable, battery operated, continuous-action dispenser, employing an orifice plate in soldered connection with a ceramic piezoelectric element, capable of long periods of use with little or no variation in the delivery rate. Thus, a need exists for an improved method for joining piezoelectric transducers to orifice plates or other elements of a piezoelectric atomizer. This patent discoses a piezoelectric liquid delivery system or atomiser for production of droplets of liquid or liquid suspensions by means of a battery operated atomizer utilising an orifice plate in communication with a ceramic piezoelectric element. By use of solder joining to bond the orifice plate to the piezoelectric element, and subsequent repolarization of the piezoelectric element if necessary, superior results are achieved. Patent number: US 6382522 Publication date: May 7, 2002 Inventors: David A. Tomkins, George A Clark, Eric R.Navin, Edward J. Martens III
Si-SiC material and SiC fiberreinforced Si-SiC composites Applicant: NGK Insulators, Ltd, Japan Currently, there are newly developed ceramics,, silicon nitride and silicon carbide both having high strength. They, however, are inherently fragile and are very fragile when they have small flaws, and further have low resistance to thermal or mechanical impact. In order to overcome these drawbacks of the above ceramics, a ceramic matrix material (CMC) was developed where a continuous ceramic fiber is mixed with a ceramic. This material, has high strength and high toughness even at high temperatures, excellent impact resistance and excellent resistance to environment. It is under active study as a structural material having an ultra-high resistance to heat, in Europe, US etc. In the sintering (firing) used in production of conventional ceramic matrix material, however, no attention was paid to the CO gas generated,
and it was conducted only to introduce an inert gas by a slight pressure control mainly for prevention of Si vaporisation. Consequently, the CO gas produced during firing in association with the conversion of organic polymer into ceramic, by the reaction of free carbon (present in firing atmosphere) and O2 and the reaction of free carbon and SiO2, is liberated to form defects. These defects and the growth of .beta.-SiC crystals bring about significant deterioration of strength. Further, the pores in produced ceramic matrix material cannot be reduced to zero and their size is as large as about mm, inviting deterioration of weatherability and oxidation resistance. Further, although the conventional ceramic matrix material contains a SiC fiber inside, the thermal stress which the material receives during actual use, is caused by the difference in thermal expansion between SiC fiber and Si—C moiety. therefore, the material has had laminar peeling in some cases. The present invention relates to a Si—SiC material of Si concentration-gradient type and a SiC fiber-reinforced Si—SiC composite material of Si concentration-gradient type. The composite material has a porosity of 1.0% or less and in the composite material the Si concentration decreases gradually from the surface layer towards the innermost layer. Both are superior in properties such as weatherability, oxidation resistance, creeping resistance, strength, toughness and the like, as well as to processes for production of said materials. Patent number: US 6444063 Publication date: September 3, 2002 Inventors: Hanzawa Shigeru, Futakawa Masatoshi, Shimizu Saburo, Onuki Kaoru,Ioka Ikuo, Johan Ynte Stockmann
Photochromatic compounds, process for their preparation and their use in polymeric materials Applicant: Great Lakes Chemical GmbH, Switzerland This invention relates to photochromatic compounds belonging to the group of spiroisoindolino-oxazines, a process for their preparation and their use in polymeric materials. A further object of the present invention relates to polymeric compositions containing said photochromatic compounds and the photochromatic articles obtained from their processing. Thes have excellent photochromic characteristics, excellent stress resistance and high dyability characteristics. Patent number: US 6414057 Publication date: July 2, 2002 Inventors: Luciana Crisci, William Giroldini, Vincenzo Malatesta, Maria Lucia Wis
Photovoltaics Bulletin
13
Patents Force sensing apparatus Applicant: ASM Technology Ltd, Singapore The invention relates to force sensing apparatus for monitoring the bond force in an ultrasonic welding machine. Ultrasonic welding is commonly used for wire bonding when packaging semiconductor devices and for other bonding operations. Force sensors are used in the ultrasonic wire bonding machines to either monitor the quality of the wire bond by measuring the bond force, or to generate the required bond force in response to signals from the sensor. In some arrangements the force sensor is located in a structure which is external and isolated from the transducer. In other designs, the force sensor is mounted on the transducer body itself. Sensors residing on the body of the ultrasonic transducer are normally of the balanced strain gauge design. They measure the surface strains produced by bending the transducer during bonding and thus indirectly obtain information regarding the bond force. However, as they contact the transducer body they exert a load on the transducer, which interferes with the operation of the transducer. Force sensors located in force arms external to the bond-head are, in general, not compact. In general, piezoelectric force sensors and electrorestrictive force sensors suffer from the problem of output voltage drift. This introduces errors in successive measurements. To overcome this problem, a number of machines use two or more sensors to mutually compensate for any drift. However, this has the disadvantage of increasing cost and size of the arrangement and increases the processing required for the sensor signals. In this invention force sensing apparatus is provided for sensing deflection of a transducer in an ultrasonic welding machine. The apparatus includes a body member, a transducer holder and a force sensor. The transducer holder is adapted to hold an ultrasonic transducer and the transducer holder is fixed to the body member. The force sensor is located between adjacent surfaces of the body member and transducer holder to sense a force applied between surfaces. Patent number: US 6425514 Publication date: 30 July 2002 Inventors: Gang Ou, Gary Peter Widdowson, Ka Shing Kenny Kwan
Attachment method for piezoelectric elements Applicant: S. C. Johnson & Son Inc, USA
October 2002
The distribution of liquids by formation of a fine spray, or atomisation, is well known. One method for such distribution is to atomize a liquid by means of the acoustic vibration generated by an ultrasonic piezoelectric vibrator. Atomisers and/or dispensers fail to provide a system by which liquid to be dispersed is supplied to the vibratory mechanism/surface without resulting in corrosion, solvent activity by the active liquid, or bond failure at the point of joining of the piezoelectric element and the orifice plate, particularly when the active liquids are such as perfumes or insecticides, having high activity quotients at high rates of vibration. Moreover, the prior art has failed to provide an easily portable, battery operated, continuous-action dispenser, employing an orifice plate in soldered connection with a ceramic piezoelectric element, capable of long periods of use with little or no variation in the delivery rate. Thus, a need exists for an improved method for joining piezoelectric transducers to orifice plates or other elements of a piezoelectric atomizer. This patent discoses a piezoelectric liquid delivery system or atomiser for production of droplets of liquid or liquid suspensions by means of a battery operated atomizer utilising an orifice plate in communication with a ceramic piezoelectric element. By use of solder joining to bond the orifice plate to the piezoelectric element, and subsequent repolarization of the piezoelectric element if necessary, superior results are achieved. Patent number: US 6382522 Publication date: May 7, 2002 Inventors: David A. Tomkins, George A Clark, Eric R.Navin, Edward J. Martens III
Si-SiC material and SiC fiberreinforced Si-SiC composites Applicant: NGK Insulators, Ltd, Japan Currently, there are newly developed ceramics,, silicon nitride and silicon carbide both having high strength. They, however, are inherently fragile and are very fragile when they have small flaws, and further have low resistance to thermal or mechanical impact. In order to overcome these drawbacks of the above ceramics, a ceramic matrix material (CMC) was developed where a continuous ceramic fiber is mixed with a ceramic. This material, has high strength and high toughness even at high temperatures, excellent impact resistance and excellent resistance to environment. It is under active study as a structural material having an ultra-high resistance to heat, in Europe, US etc. In the sintering (firing) used in production of conventional ceramic matrix material, however, no attention was paid to the CO gas generated,
and it was conducted only to introduce an inert gas by a slight pressure control mainly for prevention of Si vaporisation. Consequently, the CO gas produced during firing in association with the conversion of organic polymer into ceramic, by the reaction of free carbon (present in firing atmosphere) and O2 and the reaction of free carbon and SiO2, is liberated to form defects. These defects and the growth of .beta.-SiC crystals bring about significant deterioration of strength. Further, the pores in produced ceramic matrix material cannot be reduced to zero and their size is as large as about mm, inviting deterioration of weatherability and oxidation resistance. Further, although the conventional ceramic matrix material contains a SiC fiber inside, the thermal stress which the material receives during actual use, is caused by the difference in thermal expansion between SiC fiber and Si—C moiety. therefore, the material has had laminar peeling in some cases. The present invention relates to a Si—SiC material of Si concentration-gradient type and a SiC fiber-reinforced Si—SiC composite material of Si concentration-gradient type. The composite material has a porosity of 1.0% or less and in the composite material the Si concentration decreases gradually from the surface layer towards the innermost layer. Both are superior in properties such as weatherability, oxidation resistance, creeping resistance, strength, toughness and the like, as well as to processes for production of said materials. Patent number: US 6444063 Publication date: September 3, 2002 Inventors: Hanzawa Shigeru, Futakawa Masatoshi, Shimizu Saburo, Onuki Kaoru,Ioka Ikuo, Johan Ynte Stockmann
Photochromatic compounds, process for their preparation and their use in polymeric materials Applicant: Great Lakes Chemical GmbH, Switzerland This invention relates to photochromatic compounds belonging to the group of spiroisoindolino-oxazines, a process for their preparation and their use in polymeric materials. A further object of the present invention relates to polymeric compositions containing said photochromatic compounds and the photochromatic articles obtained from their processing. Thes have excellent photochromic characteristics, excellent stress resistance and high dyability characteristics. Patent number: US 6414057 Publication date: July 2, 2002 Inventors: Luciana Crisci, William Giroldini, Vincenzo Malatesta, Maria Lucia Wis
Photovoltaics Bulletin
13