JPH0344018A - Multilayer ceramic capacitor - Google Patents

Abstract

PURPOSE:To suppress vaporization of lithium fluoride by a method wherein the internal electrodes contain lithium fluoride. CONSTITUTION:In a multilayer ceramic capacitor comprising a lithium fluoride containing dielectric sheet, lithium fluoride is contained in internal electrodes 4a to 4b. With this constitution, lithium fluoride vaporized from an effective layer and ineffective layers can be compensated by lithium fluoride contained in the internal electrodes when a green chip is baked. Further, by function of lithium fluoride as sintering assistant, the internal electrodes are sintered more quickly than the effective layer so that a dense metallic wall is formed thereby cutting vaporization of lithium fluoride from the effective layer. Thus with function of supplying and cutting lithium fluoride of the internal electrodes, vaporization of lithium fluoride from the green chip can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a multilayer ceramic capacitor composed of a dielectric sheet containing lithium fluoride.

BACKGROUND OF THE INVENTION Conventionally, a raw chip of a multilayer ceramic capacitor containing volatile components of this type has a structure as shown in FIG. In FIG. 2, 1a and 1b are ineffective layers, 2a to 2d are internal electrodes, and 3 is an effective layer.

Problems to be Solved by the Invention In such a conventional configuration, when a raw chip is fired, lithium fluoride is volatilized from the ineffective layer and the effective layer composed of dielectric sheets containing lithium fluoride, and the sintering There was a problem that the results were uneven. The present invention is intended to solve these problems, and aims to suppress volatilization of lithium fluoride.

Means for Solving the Problems In order to solve this problem, the present invention contains a fluorinated lithium oxide in the internal electrode.

Function: With this configuration, when a raw chip is fired, the lithium fluoride contained in the internal mold electrode compensates for the lithium fluoride that volatilizes from the effective layer and the ineffective layer, and furthermore, due to the action of lithium fluoride as a sintering agent, the internal Since the electrode sinteres faster than the effective layer, a dense metal wall is formed that shields the lithium fluoride from volatilizing from the effective layer. In this way, the lithium fluoride supplying action and shielding action of the internal electrodes can suppress volatilization of lithium fluoride from the raw chip.

Embodiment 1 - Figure 1 is a sectional view of a raw chip according to an embodiment of the present invention. In FIG. 1, la and lb are ineffective layers, 3 is an effective layer, and 4a to 4d are internal electrodes containing lithium fluoride. This will be explained in detail below.

Using barium titanate powder with an average particle size of 0.5 μm or less as a raw material, a barium compound is added so that Ti/Ba = 0.971, and further 0.05 to 0.48% by weight.
of lithium fluoride (LiF), and further added 2% by weight of magnesium stannate (MgSnO:+) and cerium dioxide (C
e02) at 1.0:1lli mass%, silicon dioxide (Si
After adding 0.1% by weight of 02) and 0.3% by weight of manganese dioxide (MnO2) and mixing, drying and crushing, the obtained powder was made into a sheet with a thickness of 40 μm. On the other hand, as an internal electrode, 2.0μm-0.2μm fine nickel powder 10
A mixture was prepared by adding 0,605 to 1,0 parts by weight of lithium fluoride to 0 parts by weight, adding a binder and a solvent, and mixing and kneading. Using the above dielectric sheet and internal electrodes, stack and cut to obtain a raw chip, which is heated at a temperature of 1200°C.
It was fired at an oxygen partial pressure of 10-9 to 10-10 atm to form a multilayer ceramic capacitor. The approximate dimensions of the obtained capacitor are length 2.04, width 1.2, thickness 0.7 mm, and effective layer 3.
0 μm, effective layer number: 10 layers, internal electrode thickness: 3 μm, invalid layer thickness: 1
It was 83 μm.

Table 1 shows the effective layer, ineffective layer, and internal electrodes of lithium fluoride (L
The relationship between the amount of iF) and sinterability is shown. According to Table 1,
It can be seen that a uniform sintered body can be obtained by adding a certain amount or more of lithium fluoride to the internal electrode. Incidentally, although the above embodiments have been explained using barium titanate with additives added, it is also possible to use no additives, and it is of course possible to use a compound such as strontium titanate instead of barium titanate. . Furthermore, although nickel was used as the internal electrode, it has been confirmed that nickel alloys, other base metals, and noble metals may also be used.

(Table 1) Effects of the Invention As described above, according to the present invention, by containing lithium fluoride in the internal electrode, the sinterability is improved, and as a result, the amount of lithium fluoride is reduced. The effect of reducing this can be achieved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a raw chip showing an embodiment of the present invention, and FIG. 2 is a sectional view of a raw chip of a conventional multilayer ceramic capacitor. la, lb...ineffective layer, 3...effective layer, 4a to 4d...internal electrode containing lithium fluoride.

Claims (1)

[Claims] A multilayer ceramic capacitor comprising a dielectric sheet containing lithium fluoride, the multilayer ceramic capacitor having internal electrodes containing lithium fluoride.