Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1994-04-20
1996-05-28
Simmons, David A.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
264 60, 264 61, 264 65, 361311, 3613212, 3613214, 3613215, 361277, B32B 3100, H01G 500, H01G 406
Patent
active
055207596
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for producing ceramic parts used for protecting semiconductor devices such as IC and LSI used in electronic equipments and electric equipments against high-frequency noises and anomalous high voltages such as noise, pulse and static electricity.
BACKGROUND ART
Recently, semiconductor devices such as IC and LSI have been widely used in electronic equipments or electric equipments for miniaturization of the devices and for giving multifunctions to the devices. However, the use of the semiconductor devices causes decrease in resistance of the electronic equipments and electric equipments against anomalous high voltage such as noise, pulse or static electricity.
In order to ensure the resistance of electronic equipments and electric equipments against anomalous high voltage such as noise, pulse or static electricity, film capacitors, electrolytic capacitors, semiconductor ceramic capacitors, laminated ceramic capacitors are used. These have excellent characteristics for absorption and control of noises of relatively low voltage or high-frequency noises, but they exhibit no effect on pulses or static electricity of high voltage and sometimes cause wrong operation or rupture of semiconductor devices.
In order to absorb and control pulses or static electricity of high voltage, SiC and ZnO type varistors are used. However, these have no effect for absorption and control of noises of relatively low voltage and high-frequency noises and are apt to bring about wrong operation.
Under the circumstances, SrTiO.sub.3 type varistors have been developed to be effective against noises of relatively low voltage or high-frequency noises and pulses or static electricity of high voltage.
However, owing to the high impedance of elements, the SrTiO.sub.3 type varistors also have the problems that they are low in the effects to absorb and control pulses of relatively low voltage or high-frequency noises applied to signal lines.
The inventors have noticed that the high impedance is caused by a barrier formed at electrode part. Accordingly, the object of the present invention is to attain the high effects to absorb and control pulses of relatively low voltage and high-frequency noises applied to signal lines by reducing the impedance by destroying the barrier formed at the electrode part.
DISCLOSURE OF THE INVENTION
In order to attain the above object, the present invention provides a method for manufacturing a ceramic part according to which a pulse voltage having a maximum value of 50 kV and an energy of 0.5 joule or lower and requiring a time of 200 nanoseconds or less for reaching the maximum value from an initial value and a time of 1 microsecond or less for returning to the initial value through the maximum value is applied once or more times between electrodes.
According to the above method, the following effects are obtained. That is, when an electrode layer is formed on a ceramic element comprising a composition mainly composed of, for example, SrTiO.sub.3 and fired in a reducing atmosphere and then the ceramic layer and the electrode layer are simultaneously fired in a neutral or oxidizing atmosphere, the surface of the electrode layer is oxidized to produce a portion of high resistance and a barrier is formed on the surface and inside of the electrode layer to cause increase in impedance of the element and increase in tan .delta. together with decrease in electric capacity and as a result, the effects to absorb and control noises are damaged. This barrier is generated by oxidation of the surface and inside of the electrode and since the height of the barrier is relatively low, the barrier can be removed by application of a relatively small energy such as electric energy without causing variation in varistor voltage or deterioration of the non-linear coefficient of the voltage of parts having other characteristics such as varistor characteristics.
As shown in the present invention, by applying as an electric energy a steep wave pulse voltage which is short in
REFERENCES:
patent: 3342655 (1967-09-01), Crownover
patent: 4046847 (1977-09-01), Kresge
patent: 4082906 (1978-04-01), Amin et al.
patent: 4296002 (1981-10-01), Sokoly et al.
patent: 4325763 (1982-04-01), Utsumi et al.
patent: 4551269 (1985-11-01), Hennings et al.
patent: 4571276 (1986-02-01), Akse
patent: 4607316 (1986-08-01), Wada et al.
patent: 5119062 (1992-06-01), Nakamura et al.
patent: 5268006 (1993-12-01), Ueno et al.
Noi Keiichi
Ogoshi Yoichi
Ueno Iwao
Wakahata Yasuo
Matsushita Electric - Industrial Co., Ltd.
Mayes M. Curtis
Simmons David A.
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