JPS6052569B2 - Multilayer ceramic capacitor and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multilayer ceramic capacitor and a method for manufacturing the same.

This type of capacitor is disclosed in a patent application filed in 1989-89 by the present applicant.
It can be manufactured using the sintered ceramic structure described in No. 743 and is extremely suitable for use as a component for electrical circuits. Multilayer electrical components made of ceramic materials, such as multilayer ceramic capacitors, are widely used in electrical circuits.

These capacitors generally consist of a plurality of alternating dielectric and conductive thin layers, the latter being used as internal electrodes. These capacitors are formed as a rigid unitary body with extremely high capacitance per unit volume. These common manufacturing methods involve casting a thin sheet of the desired finely ground dielectric ceramic composition using a resin as a temporary binder. The metal-containing electrode paste is then applied to predetermined areas on the sheets, often by silk-screening, to create multiple electrode areas on each sheet. After the thin plates coated in this way are properly oriented and overlapped, they are pressed and fixed. The bonded sheet green ceramic block is suitably cut to obtain individual units. These units are heated and fired to burn out the binder in the thin plates and electrode layers and to sinter the ceramic material, thereby forming a solid ceramic-metal structure. When the thin plates are properly coated, oriented, laminated and cut in this manner, the multiple electrode thin layers in each unitary body are properly aligned such that each thin layer is exposed only on one end face of the unitary body. However, immediately adjacent electrode thin layers are exposed on opposite end surfaces of the unitary body. In this way, two sets of insulated internal electrodes are formed. Next, terminal electrodes are attached to the exposed end faces of the electrodes to electrically connect the internal electrodes alternately. In the method described above, the ceramic and the internal electrode are fired together;
The metal and ceramic of the internal electrodes must withstand high temperatures of, for example, 1100C. Also, since the optimum dielectric properties of ceramics are obtained when firing is carried out in an oxidizing atmosphere, the metal must be resistant to oxidation at these temperatures. Therefore, since noble metals with high melting points, such as palladium, platinum, and their alloys with gold are used for the internal electrodes, the manufacturing cost of this type of multilayer capacitor is high. U.S. Pat. No. 29,194 discloses a method of manufacturing a laminated ceramic capacitor that does not require the presence of internal metal electrodes during firing and hardening of the ceramic.

Further, US Pat. No. 3,679,950 discloses a method of manufacturing a laminated ceramic capacitor and a laminated ceramic circuit board using relatively inexpensive metals for internal electrodes. The method described in U.S. Pat. The porous laminates are the same size, the same shape, and are oriented the same as the prior art noble metal electrodes (ie, the immediately adjacent porous laminates have open ends on opposite sides of the chip). Metal is then introduced into the porous ceramic stack and end electrodes are attached to the opposing faces to form a stacked capacitor. According to this method, lead and
Metals such as tin and silver can be used. A similar method is
Used in the production of laminated ceramic circuit boards with internal electrodes.
A particularly convenient method for introducing metal to form internal electrodes within a porous thin layer of a monolithic ceramic produced by the method described in U.S. Pat. It is to introduce.

However, a problem often arises where the metal from the molten metal bath cools and bonds two or more ceramic units together. It is therefore desirable to keep the ceramic unit separate during the introduction of the metal, but to date there is no fully satisfactory method of accomplishing this.
Furthermore, in the production of laminated ceramic elements (eg capacitors) by methods known in the art, the attachment of end face electrodes requires further firing and the electrode compositions used are expensive. In view of the above, a principal object of the present invention is to easily introduce metal into the interior of a ceramic body generally manufactured as described in U.S. Pat. and more effectively.

The purpose of this is to create a dielectric layer that consists of a large number of superimposed thin layers of solid ceramic dielectric, a metal electrode layer between these thin layers, and a dielectric ceramic that covers the entire outer periphery so that these metal electrode layers are not exposed to the outside. a first metal conductor passing through the outer wall and the plurality of thin layers of solid ceramic dielectric and passing through every other metal electrode layer but spaced from every other remaining metal electrode layer; a second metal conductive wire extending through the plurality of thin layers of solid ceramic dielectric and through every other of the remaining metal electrode layers but spaced apart from the first every other metal electrode layer; The metal as the metal electrode layer has a melting point lower than the sintering temperature of the ceramic dielectric and lower than the melting points of the first and second metal conductive wires, and the first and second metal conductive wires are This is achieved by a laminated ceramic capacitor integrally embedded in a metal electrode layer.

This multilayer porcelain capacitor consists of a plurality of thin plates made of finely ground sinterable dielectric ceramic material, coated with a heat-burnable temporary conductor in a smaller area, and The thin plates are stacked so that the temporary conductor layers are sandwiched between adjacent ceramic thin plates, and the entire outer periphery of these temporary conductor layers is sealed with a dielectric ceramic material to form a green ceramic laminate. , a pair of spaced holes are formed in this ceramic laminate, the first of which penetrates every other temporary conductor layer, and the remaining one
A second hole is spaced apart from the first temporary conductor layer, and a second hole passes through the remaining every other temporary conductor layer, but is spaced apart from the first every other temporary conductor layer. drilled,
Next, the raw ceramic laminate is fired at a temperature higher than the sintering temperature of the dielectric ceramic body to incinerate and remove the temporary conductor to form a spatial region, and then a metal conductive wire is inserted into each of the pair of holes. After the hole is inserted, a molten metal having a melting point lower than the sintering temperature of the dielectric ceramic body and lower than the melting point of the metal conductor wire is poured into the gap between the hole and the metal conductor wire inserted therein. is produced by injecting the metal melt into the spatial region through the metal conductor and then solidifying the metal melt integrally around the metal conductor.

The cross-sectional area of the linear or rod-shaped metal conductor, that is, the lead wire, is made somewhat smaller than the hole so that it can be pulled out of the hole with a certain amount of force, and the molten metal can be drawn through the gap between the lead wire and the hole. Make it possible to inject. As can be seen, the metal of the metal bath not only fills the electrode area between the dielectric thin layers to form the internal electrodes as described in U.S. Pat. It also fills the gaps.

As a result, the conductive wire inserted into the hole functions as a lead wire of a single ceramic body filled with metal. This is because each conducting wire is electrically connected to only one of the two sets of internal metal electrodes. According to the present invention, it is possible to communicate the electrode regions between the dielectric thin layers through the holes in the ceramic single body, so that this single body has no open area at the end face of the single body as in the conventional ceramic body. (In FIG. 6, the electrode region 33 terminates a little short of the left-hand end of the monolayer stack.)

That is, molten metal is introduced into the electrode area only through the holes. However, if desired, it is also possible to provide a hole for a lead wire in the ceramic unit so that the electrode area reaches the end face of the unit (in FIG. 7, the electrode area 105 is located at the left-hand end of the stacked unit). ). In this specification, the term "one electrode area" has a broad meaning, and includes not only an area where an electrode is formed inside the ceramic structure, but also an area where a temporary conductor is provided and an electrode can be formed therein in the future. and refers to an area of any shape and size known in the art of multilayer ceramic capacitors as an area forming or capable of forming an electrode.

Objects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings. The accompanying drawings are enlarged views of each embodiment according to the present invention, with the scale of the drawings changed. FIG. 1 shows an embodiment of a single laminated ceramic capacitor according to the present invention.

It consists of a sintered ceramic structure with vertically spaced horizontal thin metal layers (ie internal electrodes) 21 and 22. The electrodes 21 and 22 are arranged alternately, and in FIG. 1, the electrode 21 extends longer than the electrode 22 in the direction of the left end surface, whereas the electrode 22 extends longer than the electrode 21 in the direction of the right end surface. ing. Thus, as shown in FIG. 4, the lead wire 25 passes through the holes that are aligned vertically in close proximity to the end surface 23 and is electrically connected to only one electrode 21. Similarly, the lead wire 26 passes through the aligned hole perpendicularly and closely parallel to the end surface 24 and is electrically connected only to the other electrode 22 . The conductive wires 25 and 26, which function as the leads of the capacitor, are held in proper position by the bent portion 28 at the position where the lead wires emerge from the upper surface of the ceramic laminate, as will be described later, before providing the internal electrodes within the capacitor. The lead wire has a similar bend at the end of the lead wire at a location where it emerges from the underside of the ceramic laminate. or,
The free lower end of the conductor may be provided with a knot 29 as shown in FIG. Figure 5 is essentially similar to Figure 4, but
A partial cross-section of a smaller capacitor is shown. If desired, knots may be used in place of bends to hold the leads at the top surface of the ceramic laminate. The manufacture of the capacitor shown in FIG.
A single sintered structure, i.e., a single ceramic body or a small ceramic body, having multiple superimposed thin layers of ceramic dielectric material with intervening electrode regions was prepared using substantially the same method as described in the 95-inch specification. Form a block.

In that patent, the electrode regions are porous ceramic laminae, each laminar having a network of interconnected cavities. Also, in this patent, one electrode region extends to one end surface, and the other electrode region extends to the other end surface. In the present invention, it is necessary for the electrode area to reach the end face and open in this way. Therefore, the method of the above US patent is slightly modified. This modification consists of applying a thin layer of temporary conductor to a thin plate of dielectric ceramic material to form the electrode areas, and stacking the coated sheets so that every other electrode area is directed towards one end face and the remaining Although every other electrode region is arranged to extend longer in the direction of the other end face, the entire outer periphery including both end faces is sealed with a dielectric ceramic material so that these electrode regions are not exposed to the outside. Therefore, in the present invention, when the ceramic structure is fired, a completely sealed sintered ceramic unitary body containing two sets of thin electrode regions inside is obtained;
A conductive material, such as a metal, is later introduced into these two sets of electrode regions to form metal electrodes. In order to introduce metal into the electrode region inside the sintered ceramic unit, a pair of holes are provided in the ceramic unit as follows.

That is, one hole penetrates every other electrode region but is spaced apart from every other remaining electrode region, and the other hole penetrates said remaining every other electrode region but is spaced apart from said remaining every other electrode region. away from the first every other electrode area.
A pair of holes are bored in a single ceramic body to communicate between the top and bottom surfaces. This is shown in cross section in FIG. A portion of the ceramic structure (i.e. a single ceramic body) is shown in which the vertical holes 31 communicate with alternating electrode areas 33, and the remaining electrode areas 35 are connected by another vertical hole (not shown). and are in close communication with opposite ends (not shown) of the chip.

The holes in the ceramic unit communicating with the electrode areas may be formed by drilling or stamping. Although the holes may be formed in the ceramic unit after the ceramic unit has been fired to sinter the ceramic, it is preferable to provide the holes in the unfired, unfired ceramic unit. Before introducing the metal into the electrode area of the fired ceramic unit, the lead wire (
A conductive wire or rod) is inserted into or passed through the hole and suitably fixed in position as previously described. The diameter of the wire or rod used is somewhat smaller than the hole into which it is inserted to provide sufficient clearance around the wire for the molten metal to penetrate into the electrode area of the ceramic unit and form the desired internal electrode. Any suitable method may be used to introduce metal into the thin electrode region of the sintered ceramic unit to form the internal electrode. For example, as previously described, a sintered ceramic unit with attached leads may be placed in a suitable container at a temperature of about 35(s) to 5(1)°C.
It may be immersed in a molten lead bath maintained at Preferably, the container is located in a variable pressure enclosure. The reason for this is that in order to introduce molten metal from around the conductor wire into the electrode area of a single ceramic body, the pressure inside the sealed body must first be increased.
For example, this can be facilitated by reducing the pressure to about 76.5 mHg and then increasing the pressure after immersing the unit in molten metal. The metal is thus pressed into the ceramic unit. A pressure of about 14k9/ClI is known to be suitable for this purpose. After the metal has been introduced, the single ceramic body is removed from the metal bath, cooled, and the pressure restored. Therefore, a capacitor with lead wires attached as shown in FIG. 1 can be obtained without requiring end face electrodes and without requiring a soldering process for attaching such lead wires. In accordance with the present invention, many metals other than lead may be used to form internal electrodes within a single ceramic body. For example, tin, aluminum, copper, and alloys thereof may be used as required. Obviously, the metal or alloy used must have a low melting point so that its incorporation into the ceramic body can be carried out at moderate temperatures, and must not substantially evaporate at the operating temperatures and have no adverse effect on the ceramic dielectric material. It is preferable not to have one. The minimum temperature at which the molten metal is injected into the ceramic body clearly depends on the dimensions of the hole and electrode area, the viscosity of the molten metal, and the surface energy of the molten metal relative to the sintered ceramic material. Generally, the melting point of the metal introduced into the electrode region of the sintered ceramic unit must be lower than the sintering temperature of the unit. The metal other than the internal electrode and the lead wire in the hole filled is solidified molten metal and has the characteristics of cast metal. FIG. 11 schematically depicts one of a number of methods of manufacturing metal internal electrodes.

In this figure, reference numeral 39 indicates a suitable container or enclosure. A container 40 made of a suitable material and containing the molten metal bath used is placed therein. The metal bath is heated by a suitable method not shown to maintain the metal at a suitable temperature. Similarly, a carrier is provided inside the closed body. Although the construction of the carrier may vary, it is preferred that the carrier include a support bar 42 that reciprocates in the vertical direction. A spring clip 43 is attached to the lower end of this bar 42, thereby allowing the previously described sintered ceramic structure, i.e. the ceramic unit 4
One or both of the lead wires 44 attached to 5 are detachably held. Therefore, the single ceramic body 45 is sealed in the sealed body 3.
9, the pressure inside the enclosure is reduced by means of a suitably connected vacuum pump (not shown), and the unit is then lowered by means of the rod 42 into the molten metal bath.

The pressure inside the enclosure is then increased by suitable means (not shown) to force the molten metal around lead wire 44 into the electrode area within the ceramic unit. Compressed gas from any suitable source may be used as the pressure medium. Then,
The rod 42 is raised to remove the ceramic unit 45 from the metal bath, cool it sufficiently to solidify the metal therein, and then remove the pressure. The manufactured capacitor is then removed and replaced with another ceramic unit and the metal pressing process is repeated. Other methods and devices may be used to introduce molten metal into the sintered ceramic unit. For example, under certain conditions, evacuation of the enclosure may occur after immersion of the ceramic unit into the molten metal bath. Similarly, multiple carriers may be provided and two or more ceramic units may be immersed simultaneously into the metal bath. If desired, the metal introduction equipment may be automated to continuously produce finished capacitors. FIG. 8 shows an example of an arrangement for providing leads in a multilayer ceramic capacitor according to the invention before introducing metal into the electrode area between the thin dielectric layers.
FIG. 8 is a sectional view perpendicular to FIG.
The holes 47 and 48 in the ceramic unit, which pass through the two sets of electrode regions 49 and 50, respectively, between the thin dielectric layer 51 are oversized and are slanted rather than vertical. Therefore, after the conductors or rods (not shown) for the leads have been inserted into the holes 47 and 48 and the molten metal has been introduced into the regions 49 and 50 through the holes around the leads, the conductors or The contact area between the bar and the internal electrode formed of metal in the electrode area is somewhat increased. FIG. 9 and FIG. 10 show reference examples.

Here, before firing the ceramic unit and filling the electrode region therein with metal, a cavity is provided in the side of the unfired ceramic unit. Single sintered ceramic body 52
Each such cavity within communicates with a pair of electrode regions 55 and 56 located between thin dielectric ceramic layers 53 (one of cavities 54 is shown in FIG. 10). Therefore, the cavity 5
4 communicates and couples with electrode areas 55, while similar cavities (not shown) at opposite ends of the ceramic unit communicate with alternating electrode areas 56. After firing and before introduction of molten metal into electrode regions 55 and 56, flattened end 57 of bar or conductor 58 is inserted into generally rectangular cavity 54 and a similar flattened bar or conductor (not shown) is inserted into generally rectangular cavity 54. are inserted into corresponding cavities (not shown) in opposite ends of the ceramic unit. The ends of the conductive wires or rods fit well within the cavity so that they are retained by frictional forces and do not fall out with some force. At the same time, however, this fit prevents molten metal from penetrating into the cavity around the flattened end and into the respective electrode area communicating with it when the ceramic unit is immersed in a molten metal bath. Do not make them so close that they interfere with After the metal-loaded unit has been removed from the metal bath and cooled, the flat conductor or rod end is firmly held in the cavity and the electrical connection between the lead wire and the internal metal electrode is maintained well. Figures 2 and 3
The figure shows another embodiment according to the invention.

In this embodiment, the laminated ceramic capacitor 59 includes two sets of internal metal electrodes 60 and 61, which are present on every other pair. Each of the electrodes 60 extends beyond the electrode 61 towards the front end of the capacitor, and each of the electrodes 61 extends beyond the electrode 60 towards the back end of the capacitor, but none of these electrodes are exposed to the exterior of the capacitor. Near the front end of capacitor 59 (FIG. 2), lead wire 62 is inserted through the spaced-apart hole, passing through the thin sintered ceramic layer and electrode 60, and across the bottom of the capacitor. The capacitor thus has a free end of the lead wire projecting from its top surface. As shown in the figure, the hole for the lead wire 62 is appropriately positioned so that the lead wire connects to the electrode 60 near the end of its forwardly protruding portion, but does not connect to the electrode 61. Lead. A lead wire 64, similar to wire 62, is provided near the rear end of the capacitor and passes through the same hole through the center line in the ceramic thin layer 63. This hole should be properly positioned so that the lead wire 6
4 is connected to the internal electrode 61 but not to the electrode 60. Leads 62 and 64 are inserted into the ceramic unit before the metal is injected into the unit, and bends 66 or knots are provided at the free ends of the leads as in FIG.
Prevent falling off before injection. In manufacturing the capacitors shown in FIGS. 2 and 3, a method very similar to that of the aforementioned US patent is used.

The green ceramic unit is created by alternating thin layers of temporarily bonded dielectric ceramic material with thin layers of smaller area temporary conductor. Holes are then drilled or otherwise drilled through these thin layers and placed in place.
The ceramic unit is fired to sinter the thin layers of ceramic dielectric material and burn off the thin layers of temporary conductor to form thin electrode spaces between the thin dielectric layers.

The outer edge of the temporary conductor thin layer is sealed by a dielectric ceramic material so that it is not exposed to the outside, and in addition, every other temporary conductor layer and every other remaining temporary conductor layer are opposite to each other. It extends longer in the direction of the end face so that upon firing, spaces for two sets of electrodes are formed inside the ceramic laminate. In the embodiment of FIGS. 2 and 3, the lead wire holes are provided in aligned pairs near opposite ends of the stack, with l pairs of holes passing through and communicating with one set of electrode regions. and the other pair pass through and communicate with the second set of electrode regions. Obviously, neither hole penetrates through the areas of both adjacent sets of electrodes. This is because this means a short circuit of the capacitor. After firing the single ceramic body, conductive wires that are slightly smaller in diameter than the holes are passed through each hole, with the free ends of each conductor protruding from the top surface of the fired laminate, and a portion of each conductor wire is extending across the bottom surface of the laminate from one hole in each pair to the other hole in the pair. One or both ends of one or both conductive wires are used to carry and carry a ceramic unit, which is then implanted with metal as previously described to form internal electrodes in the electrode area. Each conductive wire is electrically connected to one set of internal electrodes so that the conductive wires function as leads for the completed capacitor. The capacitor structures shown in FIGS. 2 and 3 are extremely useful in attaching capacitors to circuit boards or substrates by soldering.

An example of such use is shown in FIGS. 12 and 13, in which a spaced metallic solder 7 is placed on one side of a substrate 69 of a suitable insulating material.
0 and 11 are provided, and the solders are connected to conductors 12 and 13, respectively. A capacitor 74 constructed substantially similar to the capacitors of FIGS. 2 and 3 is connected to the solder 7 by the ends of respective leads 75 and 76 projecting from the bottom of the capacitor.
Connect to 0 and 71. In this way a firm and stable contact surface is obtained. FIG. 14 shows one of the various uses of the leads from a capacitor according to the invention, such as the one shown in FIG. As shown, leads 83 and 84 of capacitor 81, which respectively connect to alternating internal electrodes (not shown) within the capacitor, pass through respective holes 85 and 86 in circuit board 82 of a suitable insulating material. and pass through corresponding holes in conductors 87 and 88 provided on the underside of the circuit board. The leads hold capacitor 81 in place and good electrical connection between the leads and conductors 87 and 88 is achieved by soldering the leads to the conductors as shown at 89. The capacitor of the present invention is substantially hermetically sealed by being encapsulated within a sintered ceramic material and by filling the gap around the conductor in the lead hole with metal, but may be further sealed if desired. You can also. For example, in FIG. 15, a suitable sealing composition 91 is applied around the protrusion of lead 92 of capacitor 93. In FIG. Similarly, the 16th
In the figure, the entire capacitor 95 is coated with a suitable material 96.
and lead wires 97 and 98.
can be sealed around. Known polyethylene or epoxy resins designed for encapsulating electrical components may be used. These suitable sealing and encapsulating materials are commercially available. Capacitors of the types shown in Figures 1, 2, 5, and 18, as well as capacitors manufactured with internal metal electrodes inside ceramic laminates of the types shown in Figures 6 and 8, are similarly manufactured. Can be sealed. As previously mentioned, capacitors according to the invention do not require end face electrodes.

This is because the metal forming the internal electrodes is introduced through holes for conducting wires or bar lead wires provided in the sintered ceramic unit. Therefore, the lead wire itself electrically connects the two sets of internal electrodes. Therefore, the electrode areas between the thin ceramic layers do not need to be exposed to the outer surface of the single ceramic body. However, if necessary,
After these are exposed and the end electrodes are attached as described below, the openings to such areas may be covered and closed from the outer end face of the unitary body. Figure 7 is a reference example.
Ceramic structure 103 similar to the structure shown in FIG.
, in which a dielectric sintered ceramic thin layer 10
4 and electrode space regions 105 and 106 smaller in area and into which metal is introduced alternately.

Region 105 extends to end face 101 of the structure.
Region 106 similarly extends to an opposite end surface (not shown) of structure 103. Both sets of electrode areas are surrounded on three sides by structures. An end face member 109 is provided to cover the entire surface 107. End member 109 is conveniently formed of a ceramic material, such as low melting point glass, and is hermetically insulative. The reason is that the spatial area 10
This is because the metal forming the electrodes in 5 and 106 is introduced into structure 103 via a hole with a lead wire (not shown) passing through the structure perpendicular to this region. One such hole 111 near the end face 107 of the structure 103 communicates the electrode space region 105 with the outside, and another substantially identical hole (not shown) on the opposite end face of the structure 103 communicates with the outside. It is provided nearby to achieve communication between the electrode space region 106 and the outside. Another embodiment according to the present invention is shown in FIGS. 17 to 19.

In the structure shown in FIGS. 18 and 19, reference numeral 1
19 indicates a multilayer capacitor with vertical lead wires or lead rods 121 and 122 passing through the vertical hole 120, and the lead wires are bent at the upper and lower sides of the capacitor as shown by reference numeral 123 and easily fall off. The method of manufacturing this structure will be easily understood from the developed view in FIG.

Reference numeral 125 designates a thin plate made of a finely ground dielectric ceramic material, such as barium titanate, temporarily bonded with a hot plate bonding material, such as a resin. Lower 4 thin plates 125
A temporary electrode thin film 126 made of a completely thermally combustible material (or such a material mixed with inorganic particles) is deposited on each of the electrodes. Lamina 126 is also preferably temporarily bonded with the same hot plate bonding material. A temporary conductor, that is, a temporary electrode thin layer 126 and a dielectric ceramic thin plate 125,
Assemble as described in the aforementioned US patent or the present invention. However, it should be noted that in this example, each thin layer of temporary conductor does not extend to the edge of the ceramic thin plate, and all thin layers of temporary conductor extend to the same distance from both ends. Should. This is a result of providing a relatively large spatial area of openings 127 within each temporary conductor thin film 126. The openings 127 in adjacent thin films 126 are offset from each other, and the openings in every other thin layer 126 are aligned vertically, and are pressed together to form a plurality of thin plates 125 as shown in FIG. When the membrane 126 is assembled, the material of the adjacent membrane 125 is forced into the opening 127 to form an insulating region therein. When this solid body is heated and fired at a sintering temperature, the thermally incinerable material of the temporary conductor thin film 126 is incinerated and the ceramic material within the thin plate 125 is sintered to form a single ceramic structure. This is similar to Figure 18 and Figure 1.
As shown in FIG. 9, it consists of a plurality of dielectric ceramic thin layers 129 held together by ceramic material projecting around the edges and into the opening 127. After firing, such protruding ceramic material forms insulating regions, ie, insulating islands, in the electrode space regions interposed between the thin dielectric layers 129, respectively. The dimensions of opening 127 in membrane 126 may vary.

In general, it should not be larger than necessary to achieve its function, which is achieved by integrating the upper and lower ceramic sheets of the opening during sintering to provide an insulating area within the electrode area. This is to pass the lead wire through the area. If this insulating region is larger than necessary, the capacitance will decrease. Electrodes 130 and 131 are preferably metal and lead wires 121 and 12 are heated to incinerate the thermally incinerating material of temporary conductor film 126 into the electrode area.
Molten metal is introduced through holes 120 around the 2. The introduction of molten metal into such an electrode region can be carried out, for example, in the first
This was achieved using the method shown in Figure 1. It will be done. Therefore, capacitor 1
19 consists of a plurality of compact sintered ceramic dielectric thin layers with intervening thin films of metal, ie, thin layers 130 and 131, forming internal electrodes.

As shown, the discontinuous insulating regions or areas 132 within electrode 130 are vertically centered and
The insulating region within electrode 130 also shares the same centerline, but is laterally spaced apart from the insulating region within electrode 130. Therefore, the lead wire 121 inserted through the hole 120 electrically connects to the electrode 130 within the capacitor, but does not connect to the electrode 131 that alternately overlaps the electrode 130. Similarly, lead wire 1
22 is electrically connected only to the electrode 131 internally. The holes 120 are preferably formed in the green body by drilling or punching before firing, but may also be formed after the ceramic body is fired. Normally, the holes are drilled into the thin plate 12 before assembly.
5 and the thin film 126, but for convenience of illustration, the position of the hole L is indicated by reference numeral 120a in FIG.
The dimensions of a unitary capacitor according to the invention may vary over a wide range.

In addition to varying the dimensions of the capacitor, the number and thickness of the thin dielectric layers and electrodes therein may be varied as well. It is often preferred that the thin dielectric layer be thicker than the thin conductive film, ie, the electrode, but this may vary as desired. Two dielectric thin layers with a thickness of about 0.03mm and a thickness of about 0.0025? 2. has one inner electrode of
×3.0g1. ×0. Manufacturing capacitors in the field is easy, and large-sized ones are of course possible. According to the invention, a capacitor with a predetermined capacitance is obtained by appropriate selection of dielectric material, dimensions, thickness and number of thin layers and electrodes. The thickness and additional mechanical strength of capacitors according to the invention may be adjusted by adding thin layers or films on the top or bottom of the green ceramic structure. Unprinted thin films of dielectric ceramic compositions may be used for this purpose. However, the presence of thermally burnable deposits on the top dielectric thin film or thin films of such laminates is usually not harmful. Generally, it is preferred that the thin dielectric layers and electrodes be as thin as possible.

This is because less expensive dielectric material is used, the capacitor has a higher capacitance per unit volume, and therefore less space is required in the circuit. The thickness of dielectric thin layers is determined by the need for such thin layers to be dense and non-porous and to withstand applied voltages. Irregularities in the surface or thickness of thin films of dielectric material create problems in the formation of capacitors using very thin thin films of pseudoconductor. The reason for this is that such irregularities can become clogged after firing, but it is generally preferable to make the electrode or conductive thin film thinner than the dielectric thin layer. The dimensions of the leads provided in the multilayer capacitor according to the invention may vary within a very wide range.

Generally, the lead wires have a diameter of about 0.2511 to about 0.25 mm.
65? It is preferred to use conductors of However, thicker or thinner conductors may be used for convenience or need. Therefore, in capacitors made of ceramic structures shown in FIGS. 9 and 10, the lead wires are generally thick. The reason for this is that the ends are flattened and substantially connect with the thin metal film within the capacitor. In large-sized capacitors, the lead wire may be a bar or the like as required. The diameter of the lead wire hole in the fired ceramic unit is slightly larger than the lead wire. Generally, in order to ensure the connection between the lead wire and the metal forming the internal electrode, it is preferable to cover the lead wire with molten electrode metal. Copper is often good, but other metals can also be used. The capacitors described and illustrated so far have been rectangular.

However, the present invention also encompasses the manufacture of capacitors of other shapes. Therefore, if it has multiple sets of independent electrodes, and each set has two or more protruding lead wires electrically connected to the electrodes, it can be shaped into a triangular, hexagonal, or oval shape as required. or any other desired shape. The multilayer ceramic capacitor according to the present invention may use any ceramic composition suitable for the production of such thin layers as described in the above-mentioned U.S. patents and may include The electrode region of may be fabricated using any suitable composition described in said patent.
However, other suitable compositions may be used if desired. Preferably, the composition forming the dielectric film comprises a finely divided ceramic material that forms a solid ceramic body that can be sintered. They also preferably contain a thermally incinerable temporary binder. The thin film used to form the temporary conductor within the green body may be formed of any of the compositions described in the above-referenced US patents or other suitable compositions, as previously described. Preferably, such a temporary conductor thin film is made of a thermally incinerating material. In any case,
After firing the ceramic body, the space occupied by the temporary conductor is
It forms a spatial region, which is at least about 40% empty and is filled with molten metal to form an electrode. As used herein, the term ``dense'' refers to the fact that the material absorbs virtually no water when immersed in water, and ``thin'' is a relative term; for example, for a thin layer of ceramic, 0. .511m or less. However, such thin layers may also be thicker for specific purposes. One-thermal incineration includes substances that vaporize under the conditions described herein, or that are oxidized or transformed into vaporized substances without being oxidized. As mentioned before,
This new method of forming laminated ceramic capacitors can also be readily used in the manufacture of laminated ceramic circuit boards.

FIGS. 20 and 21 show such a laminated ceramic circuit board for reference.

Circuit board 135 is comprised of three thin dielectric or insulating ceramic layers 136 that are sintered together to form a ceramic structure. Within this structure there are three internal conductors 137, 138, 139, preferably made of metal. Lead wires 140, 141, 142, 143 and 1
44 extends from the exterior of the circuit board to one or more internal conductors (in the illustrated example internal electrodes 137 and 138).
(two layers), with a thin ceramic layer on the upper and lower sides of the inner conductor. The thin layer 136 is not only around its edges, but also around its edges.
Sintered together around and between the conductors. circuit board 135
Essentially the same methods can be used in forming the capacitors described above.

For example, three sheets of finely divided dielectric or insulating ceramic material temporarily bonded with resin are assembled and secured together with a temporary conductor film between the sheets at the locations where an internal conductor is required. Such a temporary conductor, that is, a temporary conductive thin layer, is
It may be formed using the capacitor manufacturing method shown in FIGS. 17-19, and is preferably made of a thermally incinerating material. Holes for lead wires and metal introduction are provided in the formed green body, for example by drilling or punching. Such holes pass through the top and bottom ceramic layers 136 and communicate with or penetrate one or more temporary conductors. During firing, the temporary conductor thin layer is burned off and the thin ceramic material is sintered to form a single ceramic structure into which molten metal is introduced to form the internal electrodes. Molten metal is introduced into such regions through holes through the top or bottom ceramic layers in the same manner as previously described. Similar to the capacitor manufacturing method described above, a lead wire such as a rod or a conducting wire is inserted into the hole before introducing the molten metal, and this introduction may be performed using the apparatus shown in FIG. The shape of the lead may vary, and the lead may extend into or through one or more internal electrodes. The leads may be bent or thinned within the circuit board as shown at 146. Similar to capacitor manufacturing, the cross section of the lead wire or rod is made slightly smaller than the hole into which it is inserted, and molten metal is injected from around it to form internal electrodes. Various metals and alloys may be used, provided that they have a temperature lower than the sintering temperature of the structure and the melting point of the leads.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a multilayer ceramic capacitor according to the present invention;
FIG. 2 is a top plan view of a modified example of a multilayer ceramic capacitor according to the present invention, FIG. 3 is a vertical cross-sectional view taken along line 3-3 in FIG.
Figure 4 is a partial vertical cross-sectional view taken along the line 4--4 in Figure 1, Figure 5 is a partial vertical cross-sectional view similar to Figure 4 showing a modified lead wire arrangement, and Figure 6 is a partial vertical cross-sectional view of the lead wire inside the ceramic body. A partial vertical sectional view of a ceramic body for forming a multilayer capacitor before insertion and introduction of metal, Figure 7 is a partial vertical sectional view similar to Figure 6 showing a reference example using an end face member, and Figure 8 is a diagram for lead wires. A partial vertical sectional view similar to Fig. 6 showing a modified arrangement of the holes, Fig. 9 a partial vertical sectional view showing a reference example of the arrangement for attaching the lead wire to the capacitor, and Fig. 10 with the lead wire removed. Partial side view on line 10-10 of Fig. 9, No. 11
Figure 12 is a schematic diagram showing the method of supporting a ceramic body and introducing metal into its electrode area; Figure 12 is a side view of a multilayer capacitor according to the invention placed on solder of a circuit board (shown in cross section); , FIG. 13 is a top plan view of the structure shown in FIG. 12, and FIG. 14 is a multilayer capacitor according to the present invention mounted by a lead wire passing through a hole in a circuit board (shown in cross section). FIG. 15 is a partial sectional view showing a method of sealing the lead wire of a capacitor according to the present invention, and FIG. 16 is a side view of FIG.
17 is a partially sectional view showing a fully encapsulated multilayer capacitor according to the present invention, FIG. 17 is an enlarged perspective view showing another modification of the present invention, and FIG. 18-18 in Figure 17 of the manufactured multilayer capacitor
19 is a vertical sectional view taken along line 19-19 in FIG. 18; FIG. 20 is a vertical sectional view taken along line 20-20 in FIG. The figure is the second
FIG. 2 is a vertical sectional view taken along the line 21-21 of FIG. 21, 22... Electrode (thin metal layer), 23...
...Side surface, 24...Other side surface of the capacitor, 25,2
6... Lead wire, 28... Bent part, 29
...Knot, 31...Vertical hole, 33
, 35... Electrode area, 39... Container (closed body), 40... Container, 42... Support rod portion, 43
... Spring clip, 44 ... Lead wire, 47, 48 ... Hole, 49, 50 ...
Electrode region, 52... Sintered ceramic single body, 5
3...Thin layer, 54...Vacancy, 55,
56... Electrode area, 57... Flat end, 58... Bar (conductor wire), 59... Capacitor, 60, 61... Electrode , 62, 64...
・Lead wire, 63... Thin layer, 69... Substrate, 70, 71... Solder, 72, 73...
・Conductor, 74... Capacitor, 75, 76...
・Lead wire, 81...Capacitor, 82...
・Circuit board, 83, 84... Lead wire, 85, 86
...hole, 87, 88...conductor, 91...
... Sealing composition, 92 ... Lead wire, 9
3... Capacitor, 95... Capacitor,
96...Coating, 97,98...Lead wire, 103...Ceramic structure, 104...
...Thin layer, 105,106...Spatial region, 10
7... Structure end face, 109... End face member,
111... Hole, 119... Multilayer capacitor, 120... Vertical hole, 121, 122
...Lead wire (lead bar material), 125...
・Thin plate, 126...Temporary conductor thin film, 127...
...Opening, 129...Dielectric ceramic thin layer, 130, 131...Electrode, 135...
・Circuit board.

Claims (1)

[Scope of Claims] 1. A plurality of superimposed thin layers of dense ceramic dielectric material,
A metal electrode layer existing between these thin layers, a dielectric ceramic outer wall covering the entire outer circumference so that these metal electrode layers are not exposed to the outside, and a dielectric ceramic outer wall that covers the entire outer circumference so that these metal electrode layers are not exposed to the outside; a first metal conductor passing through every other metal electrode layer but spaced from every other remaining metal electrode layer; a first metal conductor passing through said plurality of thin layers of solid ceramic dielectric and said remaining one; a second metal conducting wire passing through every other metal electrode layer but spaced apart from the first every other metal electrode layer, the metal serving as the metal electrode layer being lower than the sintering temperature of the ceramic dielectric. and has a melting point lower than that of the first and second metal conductive wires, and the first and second metal conductive wires are integrally embedded in the metal electrode layer. capacitor. 2. The multilayer ceramic capacitor according to claim 1, wherein the metal electrode layer is thinner than the ceramic thin layer adjacent thereto. 3 Thickness of metal electrode layer is 0.0025 mm to 0.025 mm
3. The multilayer ceramic capacitor according to claim 2, wherein the capacitor is mm. 4. Each metal electrode layer is provided with an insulating region made of a ceramic material integrally formed with the adjacent ceramic thin layer on both sides, and a first metal is provided in the insulating region present in every other metal electrode layer. 2. The laminated ceramic capacitor according to claim 1, wherein the conductive wire is passed through the capacitor and the second metal conductive wire is passed through an insulating region existing in every other remaining metal electrode layer. 5. Forming a plurality of thin plates from a finely ground sinterable dielectric ceramic material, applying a heat-burnable temporary conductor to these thin plates in a smaller area, and adjoining each of these coated thin plates. A raw ceramic laminate is formed by overlapping the temporary conductor layers so as to be sandwiched between the ceramic thin plates, and sealing the entire outer periphery of these temporary conductor layers with a dielectric ceramic material. a pair of spaced apart holes such that the first hole penetrates every other temporary conductor layer but is spaced apart from every other remaining temporary conductor layer; Drilling is performed so as to penetrate through every other remaining temporary conductor layer but spaced apart from every other first temporary conductor layer, and then the sintering process is performed at a temperature equal to or higher than the sintering temperature of the dielectric ceramic body. A space region is formed by firing the ceramic laminate and removing the temporary conductor, and then, after inserting metal conductive wires into each of the pair of holes, the temperature is lower than the sintering temperature of the dielectric ceramic body. injecting a metal melt having a melting point lower than that of the metal conductor into the spatial region through the gap between the hole and the metal conductor inserted therein, and then injecting the metal melt into the spatial region; A method for manufacturing a multilayer ceramic capacitor, characterized by integrally coagulating it around the metal conductive wire. 6. A method according to claim 5, characterized in that the temporary conductor is applied onto the ceramic thin plate to a thickness thinner than the thin ceramic plate. 7 Provide an insulating region made of the same material as the thin plate in each of the temporary conductor layers, so that one hole penetrates the insulating region existing in every other temporary conductor layer, and 6. The method according to claim 5, wherein a pair of holes are formed so that the other hole passes through an insulating region existing in the temporary conductor layer.