Bottles and jars – Closures – Stopper type
Reexamination Certificate
1998-11-12
2001-12-11
Abraham, Fetsum (Department: 2815)
Bottles and jars
Closures
Stopper type
C257S355000, C257S173000, C338S049000, C338S066000, C338S021000
Reexamination Certificate
active
06328176
ABSTRACT:
FIELD OF INVENTION
Subject of the present invention belongs to the field of protective electronic elements, used in safeguarding of other electronic elements and devices against voltage and current strokes, and against high and low-frequency disturbances.
TECHNICAL PROBLEM
Miniaturisation and increase of complexity of contemporary electronic elements and systems, as well as their increasingly wider application simultaneously increase their sensitivity to electronic discharge (ESD), voltage excess and strokes and frequency disturbances. These phenomena may disable normal functioning of separate components, decrease their stability and reliability and may even destroy them. In this way above phenomena jeopardise normal functioning of very complex and expensive electronic systems Sources of these phenomena may be various. For instance the largest source of electrostatic discharge is man itself in the process of manipulation with electronic devices. Most typical source of voltage strokes is lightning, which induces charge in electrical and telecommunication lines, this charge being transferred through the lines to electronic elements. And some of electronic elements themselves (e.g. electromotor, relay) induce disturbances of various frequencies and emit them in their closest surrounding. Thus each separate electronic component and its part shall be protected with special components that provide such protection. On the other hand this means that disturbance emission shall be prevented at the source.
Only use of components, with following properties may provide protection against ESD and voltage strokes: non-linear I-U characteristic, short response time and ability to absorb larger amounts of energy. Such characteristics are available in some elements, like Zener diode, multilayer ZnO polycrystalline diode (Varicon), varistor, and condensers with varistor characteristic or self-limited breakthrough.
The simplest elements for protection against frequency disturbances are condensers with capacitance up to do 100 nF for high frequencies and in case of lower or radio frequencies with capacitance up to 2000 nF.
Consequently it is clear that in order to protect against all mentioned undesired phenomena, such protective component shall have all required properties: non-linear I-U characteristic, short response time, ability to absorb larger amount of energy, and adjustable capacitance in range from 10 to 2000 nF. Beside that it must be smaller than any existing solutions and shall offer surface mounting option with terminal leads.
Subject of this invention, multifunctional component has exactly such properties.
STATE OF ART
Beside the most expensive solution, namely use of two discrete elements in parallel electrical connection e.g. combinations Zener diode—condenser or varistor-condenser, there are some other contemporary solutions one of which is condenser with varistor properties as described in European Patent 418394A. Mentioned condenser is based on SrTiO
3
, which provides high value of dielectric constant (&egr;>20000). Multilayer manufacturing technology provides wide scope of capacitance (10-2000 nF) at relatively small dimensions. However its worst side is, bad varistor characteristic and low value of non-linearity coefficient, soft knee and also high leakage current, high value of breakthrough voltage temperature coefficient and very narrow range of operating voltage. Further more materials for manufacturing such elements and production technology are very expensive. In U.S. Pat. No. 5,146,200 hybrid bond between multilayer chip varistor and multilayer chip condenser is disclosed. Physical bond of these two elements is achieved with gluing and parallel electrical connection is achieved with soldering.
Components as self-limiting multilayer condenser as shown in U.S. Pat. No. 4,729,058 and multilayer ZnO polycrystalline diode (Varicon diode) have very non-linear I-U characteristic and high self capacitance, which may within real dimensions reach up to 100 nF. In that way these two mentioned components provide protection against ESD and voltage strokes and effectively filter high frequency disturbances, but not low frequency disturbances.
DESCRIPTION OF INVENTION
New multifunctional component is based on the following facts:
self-limiting multilayer condenser and Varicon diode have such properties, which provide effective protection against ESD and voltage strokes in voltage range from 4 to 150 V
contemporary commercially available chip condensers have very high capacitance while dimensions are small
both components have similar shape and similar dimensions.
Present invention proves that low temperature scorching provides possibility to create monolith element from two discrete elements, this newly created element preserving all unchanged functions of both discrete elements, which are mutually electrically parallel connected in new element.
As mentioned above, two discrete components are used to produce this new component. One of them must provide good ESD protection and good protection against voltage strokes. To meet these demands self-limiting condenser or Varicon diode may be used, both have excellent properties of protective component.
Second component only completes already high self capacitance of Varicon diode or self-limiting condenser up to preferred value, which is necessary for successful protection against high or low frequency disturbances. For this purposes use of multilayer ceramic condenser is preferred. Ceramic condenser provides desired capacitance, even up to 2000 nF and is manufactured in similar shapes and dimensions as Varicon diode or self-limiting condenser. Both elements to bond shall have equal planar dimensions (wideness and length) and their largest sides must be even.
FIG. 1
shows Varicon diode chip (
1
) and condenser chip (
2
), each separately. As shown in
FIG. 1
, both components have same shape, equal planar dimensions, and on their shortest sides outer silver electrodes (
3
) and (
4
), which are already formed to allow electrical checking of both discrete components. Physical bond between two chips is made in such manner, that thin layer of suspension (
7
) is brought on only one of two largest area of Varicon diode or condenser, in such way to cover whole area of the chip between two electrodes (
5
). Suspension is composed from dust of low temperature high resistant glass (frite), with temperature of glassification between 500° and 800° C., binder and solvent, which allow glass (frite) as a glass paste, to be placed to the chip surface with printing, brush or in some other manner. Thickness of the suspension layer (
7
) brought to the chip surface is between 10 &mgr;m and 500 &mgr;m. Immediately after suspension is placed, second unplastered chip is placed with its larger side on the plastered side of the first chip in such manner that all edges are even, and their outer electrodes (
3
) and (
4
) fall in, and lay one upon another on both sides of the chips, as shown in FIG.
2
. Both chips with glass inter layer (
7
) form sandwich structure. So placed chips are then scorched at temperature between temperature high resistant glass (frite), with temperature of glassification between 500° and 800° C. Binder and solvent evaporate at lower temperatures so only glass remains between chips (
1
) in (
2
). At certain temperature glass liquefies and diffuses in bodies of both components. Depth of diffusion may be controlled via glassification parameters (time and temperature) to ensure that glass will not diffuse to inner electrodes depth. In certain temperature range glass turns into thin amorphous layer with good mechanical, heat and insulating properties, after cooling. Glass layer (
7
) is very good bound with both chips, due diffusion into both chip bodies. In that way, with glass layer (
7
) very good mechanical bond between both elements is achieved, and the surface between both elements has no porosity. Therefore we may say, that with glass, one monolith element composed of two discrete elements is created from two discrete elements.
Abraham Fetsum
Cook & Franks S.C.
Keko-Varicon
Ziolkowski Timthoy J.
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