Electricity: electrical systems and devices – Electrostatic capacitors – Fixed capacitor
Reexamination Certificate
1999-04-16
2001-09-04
Reichard, Dean A. (Department: 2831)
Electricity: electrical systems and devices
Electrostatic capacitors
Fixed capacitor
C361S301400, C361S303000, C361S312000, C029S025420
Reexamination Certificate
active
06285542
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to small electronic components adapted to be mounted on a larger circuit board. More particularly, the invention relates to an ultra-small device having multiple circuits of passive components for use in a variety of applications.
For some time, the design of various electronic components has been driven by a general industry trend toward miniaturization. In this regard, a need exists for ever smaller electronic components having selected operating characteristics. For example, it may be desirable in certain applications to provide a very small device having an array of individual filter circuits. Such a device may be used in various applications for providing AC terminations and low pass filtering, as well as EMI and RFI filtering. In addition, ever-increasing clock frequencies in electronic equipment require electronic components having smaller levels of inherent series inductance (ISL).
SUMMARY OF THE INVENTION
The present invention recognizes various disadvantages of prior art constructions and methods. Accordingly, it is an object of the present invention to provide a novel electronic component.
It is a further object of the present invention to provide a novel array of multiple circuits in a singular package of small size.
It is a further object of the present invention to provide a novel array of multiple circuits in a singular package that exhibits a low inherent series inductance.
It is a further object of the present invention to provide a novel array wherein capacitors of the individual circuits therein may each have a relatively large capacitance value.
It is a still further object of the present invention to provide a novel RC array device of the thin film type.
It is an additional object of the present invention to provide a method of manufacturing a thin film circuit array.
Some of these objects are achieved by a miniature array device for inverted mounting to a surface. The device comprises a substrate having predetermined width and length dimensions. A plurality of thin film RC circuits are located on the substrate, each including at least one terminal pad for connection to external circuitry. An encapsulate is disposed over the RC circuits and defines openings therein to expose the terminal pads. Solder material is located in the openings defined in the encapsulate.
Often, the encapsulate may comprise an inner compliant layer and an outer encapsulate layer. In such embodiments, the opening will be defined in the outer encapsulate layer. The compliant layer will serve to absorb stress between the array device and the underlying circuit board.
In exemplary embodiments, at least four RC circuits may be provided on the substrate. Each of the RC circuits may comprise at least one resistor having a value in a range of approximately 5 ohms to 500 kilo-ohms. At least one capacitor having a value of 4 picofarads to approximately 100,000 picofarads may also be provided in each of the RC circuits. Frequently, the resistor and capacitor provided in at least some of the RC circuits may be connected to provide a respective series RC circuit. It should be appreciated that other types of connections as would be apparent to those skilled in the art, such as parallel or distributed connections, may also be utilized in accordance with the present invention.
Often, a dielectric material of relatively high dielectric constant will be used in the capacitors of the RC circuits. For example, the dielectric material may have a dielectric constant of at least 100. In some cases, the dielectric constant may be as high as 10,000. Often, it will be desirable to utilize a lead-based dielectric material, such as a PZT dielectric material. Due to the high dielectric constant, the dielectric layer may have a thickness as low as about 0.1 to 2 &mgr;m.
Each of the RC circuits will preferably comprise a plurality of layers patterned to form predetermined circuit elements. Where the layers are conductive, the conductive layers may consist of more than one material in alloy, sublayer or lattice structure. In some embodiments, the plurality of layers may include a first conductive pattern defining at least one first capacitor plate. A dielectric layer is juxtaposed to the first capacitor plate. A second conductive pattern defines at least one second capacitor plate situated in relation to the first capacitor plate so as to form a capacitor. A thin film resistor is also provided, electrically connected to the second capacitor plate.
Often, the thin film resistor may be formed from a patterned combination having a conductive layer contiguous to a resistor layer. A portion of the conductive layer is removed from the resistor layer to provide a predetermined resistor value. In such embodiments, a terminal conductive layer defining the terminal pads may also be provided.
In other exemplary embodiments, the plurality of layers may include a first conductive pattern defining at least one first capacitor plate. A dielectric layer is juxtaposed to the first capacitor plate. A patterned combination including a conductive layer and contiguous resistor layer is also provided, part of which defines a second capacitor plate. The second capacitor plate is situated with respect to the first capacitor plate so as to form a capacitor. In addition, the conductive layer is removed in a portion of the patterned combination so as to provide a predetermined resistor value. The patterned combination may further define one of the terminal pads.
Other objects of the present invention are achieved by a miniature array device for inverted mounting to a surface. The device comprises a substrate having predetermined width and length dimensions. A plurality of thin film RC circuits are located on the substrate. Each of the RC circuits includes a first conductive pattern defining at least one first capacitor plate. A dielectric layer is disposed on the first capacitor plate. A second conductive pattern defining at least one second capacitor plate is situated in relation to the first capacitor plate so as to form a capacitor. A thin film resistor is electrically connected to the second capacitor plate.
In some exemplary embodiments, the thin film resistor is formed from a patterned combination including a conductive layer contiguous to a resistor layer. A portion of the conductive layer is removed from the resistor layer to provide a predetermined resistor value. Often, a terminal conductive layer will also be provided to define the terminal pads. An encapsulate may be disposed over the RC circuits and defined to expose the respective terminal pads.
Still further objects of the present invention are achieved by a miniature array device for inverted mounting to a surface. The device comprises a substrate having predetermined width and length dimensions. A plurality of thin film RC circuits are located on the substrate. Each of the RC circuits includes a first conductive pattern defining at least one first capacitor plate. A dielectric layer is juxtaposed to the first capacitor plate. A patterned combination is also provided, comprising a conductive layer contiguous to a resistor layer. Part of the patterned combination is situated in relation to the first capacitor plate so as to form a capacitor. The conductive layer is removed from the resistor layer in a portion of the patterned combination so as to provide a predetermined resistor value.
In some exemplary embodiments, the patterned combination further defines terminal pads of the RC circuits. An encapsulate may be disposed over the RC circuits and defined to expose the terminal pads.
If a substrate of oxidized silicon is used, a via may be formed to connect one of the conductive metal layers to the conductive silicon beneath the oxidation layer. The connection is made simultaneously with the deposition and patterning of the metal layer. In this way, an electrical ground may be established to enhance the electrical performance of the circuit.
Additional objects of the present invention are achieved by a method
Heistand, II Robert H.
Kennedy, III Robert M.
Korony Gheorghe
Liu Donghang
Mevissen Jeffrey P.
AVX Corporation
Dority & Manning P.A.
Reichard Dean A.
Thomas Eric
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