JPH02180401A - Ceramic resonator and manufacture thereof - Google Patents

Abstract

PURPOSE:To reduce costs and to improve a Q characteristic by means of the base-metal operation of an electrode material and simplification of processes by forming an electrode layer by means of electroless copper plating through a medium layer consisting of a noble metal ultra-particulate sol on the surface of a cylindrical ferroelectric ceramic sintered body. CONSTITUTION:The edge part of an element is made round by barrel-polishing a ceramic sintered body 4, etc., and the whole surface is made rough by etching- treatment in a hydrofluoric acid solution. Next, the cylindrical ceramic sintered body 4 is dipped to the catalytic solution consisting of the noble metal ultra- particulate sol, and a catalytic layer 6 is deposited on the whole internal and external surfaces of a through hole 5, or deposited to the selective surfaces by applying resist to the surfaces as needed. Then the body is dipped to the electroless copper plating solution consisting of the alkali solution of copper complex salt and formalin, the metal copper is deposited on the surface of the medium layer 6 consisting of the noble metal ultra-particulate sol to the width 5 to 10mu to form an electrode layer 7. Thus, the electrode layer 7 excellent for uniformity and adhesiveness can be formed on the surface of the sintered body 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a high frequency electrostatic resonator and a manufacturing method thereof.

BACKGROUND OF THE INVENTION In recent years, with the advancement of information and communication equipment, the demand for high-frequency resonators has increased significantly, and along with this, the need for smaller resonators, higher performance, and lower prices has also increased.

A conventional cetsmic resonator is as shown in FIG. 3, where 1 is a ferroelectric cylindrical cetsmic sintered body, 2 is a through hole, and 3 is an electrode layer.

This cetsmic resonator is generally made of a ferroelectric cetsmic mainly composed of barium titanate, which is made of a cylinder with arbitrary dimensions.
A conductive paste containing a mixture of silver powder and glass frit is selectively applied to the entire or part of the inner and outer peripheral surfaces of the through hole 2 of the Cetsmic sintered body 1, which is formed by molding into a shape and sintering at high temperatures. The electrode layer 3 was formed by firing this at a high temperature of 600 to 800 degrees.

On the other hand, recently, as an electrode formation method aimed at lowering the price and improving the performance of cetsmic resonators, there is also a method of directly forming an electrode layer on a ferroelectric cetsmic sintered body sintered at high temperature by electroless steel plating. It is being done.

Problems to be Solved by the Invention However, in the above-mentioned cetsmic resonator, the former one in which the electrode layer 3 is formed of a sintered body of silver and glass is not only expensive because the electrode material used is a noble metal. Since the glass layer is interposed between the ceramic sintered body 1 and the silver conductor, there is a problem in that the high frequency characteristics, particularly the Q characteristics, are deteriorated.

Furthermore, the method for uniformly applying silver paste to the inner and outer peripheral surfaces of the through-holes 2 of the cylindrical sintered body 1 is extremely complicated, and there is a problem in that it lacks mass productivity.

In addition, in the case where an electrode layer made of metallic copper is directly formed on the surface of a ferroelectric ceramic sintered body by the latter electroless plating method, tin and palladium hydrochloric acid are used in the catalyst application treatment performed as a pretreatment for electroless plating. A strongly acidic catalyst solution consisting of a solution is used. However, when a ferroelectric ceramic sintered body is coated with such a catalyst and electroless steel plated, the mechanical strength deteriorates due to erosion of the ceramic sintered body by a hydrochloric acid solution, and tin is added to the catalyst layer. remains, inhibiting the catalytic activity, and deteriorating the coverage and adhesion of the plating, resulting in a decline in high frequency characteristics, especially Q characteristics.

It is an object of the present invention to solve the above-mentioned problems and to provide a static resonator with excellent notation and high frequency characteristics, and a method for manufacturing the same.

Means for Solving the Problems In order to achieve the above objects, the present invention provides an electrode formed by electroless steel plating on the surface of a ferroelectric cylindrical setumic sintered body, with a catalyst layer made of ultrafine precious metal particle sol interposed therebetween. It is made up of layers.

As a result, the catalyst layer is uniformly and firmly adhered to the ceramic sintered body without any tin remaining in the catalyst layer made of ultrafine precious metal particle sol, improving the uniform adhesion of the electrode layer deposited by electroless plating. As a result, a setmic resonator with excellent high frequency characteristics was realized.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a cetsmic resonator according to a first embodiment of the present invention, and FIGS. 2a and 2b are cross-sectional views for explaining the manufacturing process of the cetsmic resonator. Figures 1 and 2
In the figure, 4 is a ferroelectric cylindrical setumic sintered body;
6 is the through hole thereof, 6 is a catalyst layer made of noble metal ultrafine particle sol, and 7 is an electrode layer.

The details of the manufacturing process for the static resonator having the above configuration will be explained below.

In the first embodiment of the present invention, a raw ferroelectric cetsumic material containing barium titanate as a main component was prepared with an outer diameter of approximately 6 m.
By molding into a cylinder with an inner diameter of 2 m and a height of approximately 8 g, and firing this cylindrical molded body at a high temperature of 120 to 1300 °C, a cylindrical setumic sintered product as shown in Fig. 1 is produced. I made all 4 bodies.

Then, this ceramic sintered body 4 was subjected to barrel polishing or the like to round the edges of the element, and further etched in a hydrofluoric acid solution to roughen the entire surface of the ceramic sintered body 4.

Next, as shown in FIG. 2B, this cylindrical ceramic sintered body 4 is immersed in a catalyst liquid consisting of precious metal ultrafine particle sol, and a resist is applied to the entire inner and outer peripheral surfaces of the through holes 6 or if necessary. Then, the catalyst layer 6 was selectively deposited.

In this case, an ultrafine particle sol consisting of a single metal such as silver, palladium, or platinum can be used as the catalyst liquid consisting of a noble metal ultrafine particle sol, but in this example, an ultrafine particle sol consisting of palladium was used.

This palladium ultrafine particle sol is dissolved in water together with sodium chloride, anionic sodium dodecylbenzenesulfonate is added as a surfactant, and then sodium borohydride is added dropwise for reduction. Both a hydrosol type consisting of ultrafine palladium particles having an average particle size of 30 to 60 particles and an organosol type consisting of ultrafine palladium particles dispersed in an organic solvent other than water such as toluene were used.

Incidentally, since all of these catalyst liquids are chemically almost neutral solutions, they do not erode the cetomic sintered body 4.
Furthermore, it was found that the adsorption properties of the ultrafine palladium particles were extremely good, and that the catalyst layer 6 could be formed evenly and firmly on the ceramic sintered body 4.

Then, the catalytically treated CETSUMIC sintered body 4 is immersed in an electroless steel plating solution consisting of an alkaline solution of copper complex salt and formalin, and as shown in FIG. Electrode layer 7 was formed by depositing copper to a thickness of 6 to 10 microns.

In this case, it was possible to form an electrode layer 7 with excellent uniformity and adhesion on the surface of the sintered body 40 using the catalyst layer 6 made of palladium ultrafine particle sol. The cetsmic resonator according to the present invention has an electrode layer formed by electroless steel plating on the surface of a cylindrical ferroelectric cetsmic sintered body, with a catalyst layer made of ultrafine precious metal particle sol interposed therebetween.

Therefore, compared to conventional silver electrodes, the electrode material is made from a base metal and the process is simplified, resulting in lower costs.
Since there is no glass insulating layer between the CETSUMIC sintered body and the electrode layer, the high frequency characteristics, especially the Q characteristics, are significantly improved. Effects such as a marked improvement in the spreadability and adhesion of electroless plating to a solid sintered body were obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a cetsmic resonator according to an embodiment of the present invention, FIGS.
The figure is a cross-sectional view of a conventional cetsmic resonator. 4...Setsumic sintered body, 6. River...through hole,
6... Catalyst layer, 7... Electrode layer. Name of agent: Patent attorney Shigetaka Awano (1 person)
Figure t5 Mihye Seok fig body Figure 6-M-Catalyst layer 7-Electric II & layer diagram!

Claims (4)

[Claims] (1) A CETSMIC resonator characterized in that an electrode layer made of electroless steel plating is formed on the surface of a ferroelectric cylindrical CETSMIC sintered body through a catalyst layer made of ultrafine noble metal particle sol. (2) A CETSUMIC resonator characterized in that a catalyst layer made of ultrafine precious metal particle sol is applied to the surface of a cylindrical CETSUMIC sintered body having ferroelectric properties, and an electrode layer is formed by electroless steel plating. manufacturing method. (3) The method for manufacturing a cetmic resonator according to claim 2, in which a hydrosol-based ultrafine particle dispersion solvent is used as the noble metal ultrafine particle sol. (4) The method for manufacturing a cetomic resonator according to claim 2, in which an organosol-based ultrafine particle dispersion solvent is used as the noble metal ultrafine particle sol.