JPH0515291B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a multilayer capacitor element, and particularly relates to a multilayer capacitor element that has a high insulation resistance value, low induction loss at high frequencies, and low electrode cost. BACKGROUND ART In recent years, multilayer ceramic capacitors have been rapidly becoming popular due to the demand for smaller and larger quantities of ceramic capacitor elements. Furthermore, as circuits become more frequent, it is becoming necessary to use multilayer ceramic capacitor elements in areas where electrolytic capacitors have conventionally been used. Multilayer ceramic capacitors are normally manufactured by a process in which internal electrodes and ceramic are fired together. Barium titanate-based materials have traditionally been used for high-permittivity ceramic capacitor materials, but because the firing temperature is as high as 1300°C, expensive metals such as Pt and Pd are used as internal electrode materials. The need arose. In response, a multilayer capacitor element has been proposed that uses a barium titanate-based material that can be fired in a low oxygen partial pressure atmosphere and uses a base metal material such as Ni as the internal electrode. (Japanese Journal of Applied Physics Supplement, 20-4 (1981), P147-150) The inventors have proposed a lead composite perovskite material that can be fired in a low oxygen partial pressure atmosphere and has high resistivity. Problems to be Solved by the Invention Conventional multilayer capacitor elements using Pd or Pt as internal electrodes have large electrode costs that are included in the element price, making it particularly difficult to realize large-capacity multilayer capacitors that require a high number of laminated layers. Multilayer capacitors using Ni for internal electrodes have the problem that the element insulation resistance value tends to decrease due to reduction of the dielectric ceramic, and dielectric loss tends to increase at high frequencies. The present invention realizes a multilayer capacitor element with high insulation resistance and low dielectric loss at high frequencies.
Another object of the present invention is to provide a multilayer capacitor element with low electrode cost. Measures to solve the problem Ng, Ni, Ti, Zn, Nb,
Components X and Pb selected from group X consisting of and W
and Cu, wherein X contains at least two of the components of group X, and the number of moles of Pb is a, and the total number of moles of the components of X is x. When 0.985≦a/b≦1.110, a composition containing Cu in an amount of 0.03% to 0.65% by weight relative to the total weight of other components in terms of Cu ² O is used, and copper or copper is used in the internal electrode layer. An alloy whose main component is Function The lead perovskite composition as described above used as the dielectric ceramic in the multilayer capacitor element of the present invention has high insulation resistance in a wide oxygen partial pressure range centered on the equilibrium oxygen partial pressure of copper at the firing temperature. Since dielectric ceramic can be obtained, when a multilayer capacitor with copper as the internal electrode is used, it is easy to control the oxygen partial pressure during firing, and a multilayer capacitor element with stable high insulation resistance can be obtained. Furthermore, since low-resistance, non-magnetic copper electrodes are used for the internal electrodes, the dielectric loss of the capacitor element at high frequencies does not decrease even when it is made into a thin plate. Also, copper is Pd,
It is cheaper than Pt etc. and can greatly reduce electrode costs. Example A material represented by the following compositional formula was used as a dielectric. A: Pb _1.00 (Mg _1/3 Nb _2/3 ) _0.70 Ti _0.19 (Ni _1/2 W _1/2 ) _0.1
1
O _3.00 + Cu ₂ O 0.2wt% B: Pb _0.985 . (Mg _1/3 Nb _2/3 ) _0.40 Ti _0.30 (Zn _1/2 W _1/2 )
_0.3
0 O _2.985 +Cu ₂ O0.65wt% C: Pb _1.110 (Ni _1/3 Nb _2/3 ) _0.79 Ti _0.21 O _3.110 +Cu ₂
O0.03wt% D: Pb _1.000 (Ni _1/3 Nb _2/3 ) _0.70 Ti _0.25 (Ni _1/2 W _1/2 ) _0.
05
O _3.00 + Cu ₂ O 0.30wt% dielectric powder was manufactured according to a normal ceramic manufacturing method. The calcination conditions were 750°C for 2 hours. The pulverized calcined powder was mixed in a ball mill with 7 wt% acrylic resin and 50 wt% solvent based on the calcined powder, and formed into a sheet with a thickness of 35 μm using a doctor blade. A material represented by the following compositional formula was used as the internal electrode. E: Cu F: Cu-5wt%Ag Metallic copper powder and metallic silver powder have a particle size of 0.5 to 2.0μm
After mixing the metal powder in a predetermined ratio, the metal powder was kneaded with 5 wt% acrylic resin and 30 wt% solvent to form an electrode paste, and an internal electrode pattern was printed on a sheet using screen printing. This was laminated so that the electrodes were drawn out alternately on the left and right sides, and then cut. The above-mentioned electrode paste was applied to the end faces from which the electrodes were drawn out alternately to form external electrodes. The laminate thus created was placed on a porcelain boat with coarse-grained zirconia placed on top of it and exposed to 1% O ₂ −
The binder was burnt out at 350°C under N ₂ gas flow. FIG. 2 shows a cross section of a magnesia porcelain container into which a laminate is placed during firing, and FIG. 3 shows a cross section of a firing furnace core tube. In the magnesia porcelain container 21, the above-mentioned calcined powder 22 is spread about 1/3 of the volume, and 200 mesh
About 1 mm of ZrO ₂ powder 23 was spread, and the burnout laminate 25 was placed thereon. After covering the magnesia porcelain lid 24 and inserting it into the furnace core tube 26 of a tubular electric furnace, the inside of the furnace core tube was degassed with a rotary pump.
The mixture was replaced with a mixed gas of N ₂ - H ₂ - _{H 2} O, and the mixed gas with the mixing ratio of N ₂ , H ₂ , and H ₂ O gas adjusted to a predetermined oxygen partial pressure was flowed at 400°C/200°C to a predetermined temperature. The temperature was raised at 400°C/hr, held for 2 hours, and then lowered at 400°C/hr. Po ₂ in the reactor core tube was determined from the voltage E(V) between the electrodes drawn from the platinum electrodes configured on the atmospheric side of the inserted stabilized zirconia oxygen sensor 27 and on the inner side of the reactor, using the following equation. Po ₂ = 0.2・exp (4FE/RT) where F is Faraday constant 96489 coulombs, R
is the gas constant 8.3144J/deg・mol, and T is the absolute temperature. The outer dimensions of the multilayer capacitor element are 2.8x1.4x0.9mm, and the effective electrode area is 1.3125mm ² (1.75x0.75mm) per layer.
mm), the thickness of the electrode layer is 2.0μm, the dielectric layer is 25.0μm per layer, there are 30 effective layers, and 2 invalid layers above and below.
Layer by layer. The multilayer capacitor element has a capacitance, tanδ
was measured at a frequency of 100Hz to 2MHz by applying an AC voltage of 1V. Further, the resistivity was determined from the value 1 minute after applying a voltage of 50 V/mm. Table 1 shows the composition of the dielectric, electrode composition, firing temperature, firing atmosphere, dielectric constant, tan δ, and resistivity of the dielectric used. FIG. 1 is a cross-sectional view of a multilayer capacitor element of the present invention, in which 11 is a dielectric layer, 12 is an internal electrode layer made of copper or an alloy mainly composed of copper, and 13 is a cross-sectional view of a multilayer capacitor element of the present invention.
is an external electrode made of copper or an alloy containing copper as a main component.

[Table] The dielectric materials used in the present invention are Ng,
In an oxide containing a component X selected from group X consisting of Ni, Ti, Zn, Nb, and W, and three components of Pb and Cu, X contains at least two of the components of group When the number of moles of is a and the total number of moles of the components _of It is a composition containing the following, and can produce dielectric porcelain with high resistance in a wide oxygen partial pressure range near the firing temperature, making it suitable for integral firing with internal electrodes made of copper or copper-based alloys. ing. If a base metal other than copper or an alloy containing copper as a main component is used for the internal electrode, the equilibrium oxygen partial pressure of the electrode metal at the dielectric firing temperature specified in the present invention is small, and the dielectric will be reduced. Alternatively, the problem of oxidation of the electrodes is expected. That is, in the present invention, a laminated layer with high insulation resistance and low dielectric loss at high frequencies can only be achieved by combining the dielectric ceramic composition defined in the claims and an electrode composition made of copper or an alloy containing copper as a main component. A capacitor element is realized. This also allows inexpensive copper to be used as the electrode. In addition to the method for manufacturing a multilayer capacitor element shown in the embodiments of the present invention, copper oxide is used as a starting material for internal electrodes, and after forming an electrode pattern on a ceramic green sheet, the copper oxide is formed at a temperature lower than the firing temperature. It can be easily inferred that an element similar to the multilayer capacitor element produced according to the embodiment of the present invention can be obtained even if a method of reduction, metallization, and subsequent firing is used. Effects of the Invention The multilayer capacitor element of the present invention provides an industrially useful multilayer capacitor element that can use inexpensive copper as internal and external electrodes, has a high insulation resistance value, and has low dielectric loss at high frequencies.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a multilayer capacitor element according to the present invention, FIG. 2 is a sectional view of a magnesia container during firing, and FIG. 3 is a sectional view of a firing furnace core tube. 11... Dielectric layer, 12... Internal electrode layer, 13
...External electrode.

Claims (1)

[Scope of Claims] 1. A multilayer capacitor element in which at least two or more internal electrode layers are laminated and drawn out alternately through dielectric ceramic layers, in which Mg, Mg,
A composition comprising an oxide containing component X selected from group X consisting of Ni, Ti, Zn, Nb, and W, and three components of Pb and Cu, wherein X is at least two of the components of group Including seeds, and the number of moles of Pb is a,
When the total number of moles of the components is x, 0.985≦a/x≦1.110, and the composition contains Cu in an amount of 0.03% or more and 0.65% or less in terms of Cu ₂ O based on the total weight of other components. 1. A multilayer capacitor element characterized in that copper or an alloy containing copper as a main component is used for internal electrode layers. 2. The multilayer capacitor element according to claim 1, wherein copper or an alloy containing copper as a main component is used as the external electrode that is directly connected to the internal electrode and configured near the end face of the multilayer capacitor element.