Patent Application
20100103586
1. Field of the Invention
The present invention relates to a multilayer ceramic capacitor and more particularly, to such a multilayer ceramic capacitor that has the terminal electrodes arranged on two diagonal corners of the dielectric body to extend the electrode pitch, preventing an electric arc effect or electrical fire caused by a surge voltage and eliminating the risk of a short circuit or other accidental events.
2. Description of the Related Art
Regular electronic products commonly use many active and passive components. An active component (such as IC or CPU) is a device that adds intelligence in some manner to the signal or data that passes through it. A passive component is device that does not have any impact on the electrical signals or the data that passes through it. Resistor, capacitor and inductor are the three major passive components. Functionally, a capacitor is an electronic device that stores a charge of static electricity and, when properly stimulated, releases this charge. This is the way bits are written to and read from computer storage. A resistor is the component of an electrical circuit that produces head while offering opposition, or resistance, to the flow of electric current. Further, an inductor is a passive electrical component with significant inductance and adapted for removing noises from electric current passing therethrough to avoid electromagnetic interference. Resistor, capacitor and inductor are used together in information, communication and consumer electronics products and other industrial products for electronic loop control.
Further, passive components are developed toward chip fabrication. Following the development tendency of integrated circuits toward high performance and high density and the creation of SMT (surface mounting technology), electronic devices of SMT chip designs are intensively used to substitute for through hole designs. In consequence, the demand for passive components that are made in a chip form rises rapidly, and the requirement for a relatively smaller size is more and more strong
A capacitor stores static electricity in the electric field between a pair of conductors (called “plates”) that are isolated from each other by a thin layer of dielectric material, thereby achieving charge storing, by-passing, filtering, tuning and osscilating functions. Further, capacitors can be classified, subject to their materials, as aluminum electrolytic capacitors, ceramic capacitors, metallized plastic thin film capacitors, tantalium capacitors and mica capacitors. Further, capacitors are classified to be fixed capacitors, variable capacitors or chip capacitors subject to the dielectric material used.
Further, ceramic capacitors include single layer ceramic capacitors and multilayer ceramic capacitors (MLCC). When compared to other low value capacitor types, multilayer ceramic capacitors have the advantages of high dielectric coefficient, excellent insulation, excellent voltage and heat resistance, high capacity, small size, high reliability, high working temperature range. Further, multilayer ceramic capacitors are suitable for mass production at low price. Further, multilayer ceramic capacitors can be directly bonded to a circuit board by means of SMT (surface mounting technology). Nowadays, multilayer ceramic capacitors have become the market main steam and, are intensively used in small-sized multifunctional electronic products.
Further, a multilayer ceramic capacitor is a capacitor constructed of alternating layers of metal and ceramic, with the ceramic material acting as the dielectric, i.e., one ceramic layer is sandwiched between two parallel electrode layers to constitute a flat capacitor and the, and then the internal electrode layers are bonded to terminal electrodes to have the flat capacitors be connected in parallel. When flat capacitors are connected in parallel, V=V1=V2=V3= . . . =Vi, Q=C*V, and therefore, C=C1+C2+C3+ . . . +Ci. Thus, the total capacity of a multilayer ceramic capacitor is the sum of the capaicity of all the flat capacitors thereof, and connecting the flat capacitors in parallel achieves increase of the capacity or the energy storage effect.
Therefore, it is desirable to provide a multilayer ceramic capacitor that extends the electrode pitch without changing or extending the designed capacitor size, avoiding the aforesaid problem.
The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a multilayer ceramic capacitor, which prevents an electric arc effect or electrical fire caused by a surge voltage, thereby eliminating the risk of a short circuit or other accidental events.
To achieve this and other objects of the present invention, the multilayer ceramic capacitor comprises a rectangular dielectric body having ceramic layers and multiple first internal electrodes and second internal electrodes alternatively arranged in between each two adjacent ceramic layers and respectively terminating in a respective contact in such a manner that the contacts of the first internal electrodes and the contacts of the second internal electrodes are respectively disposed at two diagonal corners of the dielectric body, and multiple terminal electrodes respectively bonded to the two diagonal corners of the dielectric body and respectively electrically connected with the contacts of the first internal electrodes and the contacts of the second internal electrodes.
Referring to
The dielectric body 1 comprises multiple ceramic layers 11 and a plurality of first internal electrodes 12 and second internal electrodes 13 alternatively arranged in between each two adjacent ceramic layers 11 at different elevations and respectively terminating in a respective contact 121 or 131. The contacts 121 of the first internal electrodes 12 and the contacts 131 of the second internal electrodes 13 are respectively disposed in two diagonal corners relative to the ceramic layers 11.
The terminal electrodes 2 are respectively bonded to two diagonal corners of the dielectric body 1 corresponding to the contacts 121 of the first internal electrodes 12 and the contacts 131 of the second internal electrodes 13 and respectively electrically connected with the contacts 121 of the first internal electrodes 12 and the contacts 131 of the second internal electrodes 13.
After construction of the ceramic capacitor, the terminal electrodes 2 are respectively bonded to respective metal contacts 31 of a circuit board 3 by means of SMT (surface mounting technology) (see
The fabrication of the multilayer ceramic capacitor includes the anterior brick fabrication process, an intermediate bulk fabrication process of binder burn out, dense sintering, termination dipping and termination curing steps, and a posterior fabrication process of termination plating, function testing and taping steps. This multilayer capacitor fabrication method is of the known art and not within the scope of the claims of the present invention. Therefore, no further detailed description in this regard is necessary. According to the present invention, a metal paste having high conductivity is selected and bonded to the contacts 121 of the first internal electrodes 12 and the contacts 131 of the second internal electrodes 13 under high temperature firing, thereby forming the desired two terminal electrodes 2 at two diagonal corners of the dielectric body 1. Thus, the diagonal pitch d1 between the two terminal electrodes 2 of the multilayer ceramic capacitor in accordance with the present invention (see
Referring to
When compared to the linear pitch d2 between the two terminal electrodes B of a multilayer ceramic capacitor according to the prior art (see
Therefore, the structural design of the multilayer ceramic capacitor according to the present invention prevents an electric arc effect or electrical fire caused by a surge voltage, eliminating the risk of a short circuit or other accidental events.
Referring to
From the left half of Table I, it can be seen that the electrode pitch d2 between the terminal electrodes B of the test samples according to the prior art (see
In conclusion, a multilayer ceramic capacitor in accordance with the present invention comprises a dielectric body 1, which comprises multiple ceramic layers 11 and a plurality of first internal electrodes 12 and second internal electrodes 13 alternatively arranged in between each two adjacent ceramic layers 11 at different elevations and respectively terminating in a respective contact 121 or 13, and two terminal electrodes 2 respectively electrically bonded to the contacts 121 of the first internal electrodes 12 and the contacts 131 of the second internal electrodes 13 at two diagonal corners of the dielectric body 1. By means of arranging the two terminal electrodes 2 on two diagonal corners of the dielectric body 1 to extend the electrode pitch, the invention prevents an electric arc effect or electrical fire caused by a surge voltage, eliminating the risk of a short circuit or other accidental events. Therefore, the invention greatly prolongs the capacitor service life.
Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.
