JPS59202618A - Method of producing laminated ceramic condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing an 8-layer ceramic capacitor for high frit ICs and for direct mounting on printed circuit boards.

Conventional Structures and Problems Multilayer ceramic capacitors are generally based on a laminate obtained by alternately laminating ceramic dielectric and thin film layers of palladium and/or platinum, and the internal thin metal film covers the dielectric. Silver or silver-palani at the ends to form a parallel circuit in the form of a pinch.

It has a configuration in which it is connected to a dium alloy electrode. The thickness of the dielectric used in this multilayer ceramic capacitor is about 15 to 100 μm, and the structure is such that electrodes are provided on a flat surface of such a thin dielectric and folded.

Generally, the capacitance of a capacitor is expressed as C-ε8ε〇-. Here, ε0 is the dielectric constant of vacuum, ε is the relative dielectric constant of the dielectric, S is the electrode area, and t is the distance between the electrodes. Therefore, considering the capacitance per volume, it becomes C/VOO-(y is the volume of the capacitor)2, which is inversely proportional to the square of the thickness. Therefore, when comparing the capacitance per volume of a disk-type ceramic capacitor and a multilayer ceramic capacitor, the thickness of the multilayer ceramic capacitor is approximately 1/10 of the thickness of the disk-type ceramic capacitor.
Since it is possible to obtain the same volume or about 100 times more volume. (Note that it is impossible to reduce the thickness of a disc-type ceramic capacitor in terms of strength; the current limit is around 1SOOμm.

9 In this way, g/F7 ceramic capacitors are small and have large capacitance, and are suitable for the miniaturization of electronic circuits. v) Direct attachment to printed circuit boards is becoming easier.

However, there are some drawbacks to such multilayer ceramic capacitors, one of which is defects that occur due to the thinness of the capacitor.

That is, ceramic itself is originally a polycrystalline body, and unlike a dense single crystal, it has countless pores. Such pores are also not of uniform size, and large pores also exist. It is one of the challenges to make these pores small and uniformly distributed, and although various studies have been conducted, it is still not sufficient.

The effect of such pores is to weaken moisture resistance. Special (Due to ζ nickel or tin-lead alloy plating, residual electrolyte may become a problem in processes that use electrolytes. Electrolyte X7) T
15. If moisture η) is present, the insulation resistance may decrease due to re-penetration. The silver electrodes at both ends are usually made by applying an electrode paste consisting of silver particles, glass frit particles, an organic binder, and an organic solvent to a sintered ceramic chip, drying it, and baking it in an electrode baking furnace at about 800°C. . By doing so, the ceramic and the sintered silver particles are bonded by the glass frit component, and the Pd or Pd-Ptfli electrode inside the ceramic is bonded to the end surface silver electrode. However, this sintered gamma silver electrode also has pores, and as mentioned above, the electrolyte penetrates during plating, and the glass frit component is dissolved by the electrolyte, reducing the bond strength between the end electrode and the ceramic glue, resulting in reliability. This will result in a decline in sexuality. Particularly in the case of such silver-baked electrodes, lead borosilicate glass is often used as the glass frit due to fH limitations such as baking temperature and compatibility with ceramics, which is easily contaminated by acidic plating solutions. , which caused a decrease in the adhesion force of the external electrode.

Such a situation significantly impairs the reliability of the product and often causes problems in the market.

For this reason, special attention must be paid to multilayer ceramic capacitors provided with plated electrodes.

Purpose of the Invention The present invention has been made to address the above-mentioned conventional problems.
The object of the present invention is to manufacture a multilayer ceramic capacitor having plated end electrodes with high external electrode adhesion and good moisture resistance.

Structure of the Invention In order to achieve the above object, the method for manufacturing a multilayer ceramic capacitor of the present invention includes applying silver or silver-palladium alloy electrodes to both ends of a ceramic dielectric material in which electrode layers are alternately laminated in a comb shape. This porcelain dielectric was impregnated with an anaerobic adhesive, and after removing the excess adhesive adhering to the surface, the electrodes at both ends were plated.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

71.4 parts by weight of barium titanate, 20.4 parts by weight of barium zirconate, 7.4 parts by weight of calcium titanate, 0.2 parts by weight of oxidized surface 'lEr, 0.15 parts by weight of manganese dioxide, 0.25 parts by weight of tungsten oxide. A slurry was prepared using a binder mainly composed of ethyl cellulose from a mixed powder of 0.25 g/l of aluminum oxide and 40±2 μm thick sheet was formed using a doctor blade method. After punching out this sheet to a certain size, palladium electrodes were printed. After stacking the electrode-printed sheets so that the electrodes are in a comb shape and pressing and sawing, 8.6X1. It was cut into a size of &nm x 0.69m+. This chip was heated at 1370℃±20℃ for 2
Silver paste was applied to both end faces of the sintered body obtained by firing for a period of time, and the sintered body was baked at 800°C. An anaerobic adhesive (product name: Loctite PMS-1) was applied to the thus produced laminate.
0) was vacuum impregnated at 4°C for 1 hour. Thereafter, excess adhesive on the surfaces of the ceramic and gM section electrodes was centrifuged and washed with trichlorethylene. Then 1 at 80°C
It was completely cured for 5 minutes. Next, the silver electrodes at both ends were plated with nickel to a thickness of 1 to 2 .mu.m by barrel plating, and then alloy plating of tin and lead was applied to a thickness of 1 to 2 .mu.m.

At this time, the PH (leaf ion concentration) of the plating solution is approximately 4 for the nickel plating bath and approximately 1''c for the tin and lead alloy plating bath.
'there were.

The first layer shows the multilayer ceramic capacitor of the present invention obtained in this way, in which (1) is the ceramic dielectric layer, (2
) is a palladium electrode layer, (3) is a silver electrode, (4) is a nickel plating layer, and (5) is a tin-lead alloy plating layer.

The following table shows actual measured values of external electrode adhesion of a multilayer ceramic capacitor based on the method of the present invention and a multilayer ceramic capacitor without adhesive impregnation based on the conventional method (same as the method of the present invention except for adhesive impregnation). There is C. As is clear from charcoal, the material according to the present invention has strong adhesion to the ceramic of the external electrode. Note that the external electrode adhesion force is 0 to the chip.
．． Solder the lead wires of 5 order φ and measure the tensile strength in the vertical direction using a tensile strength tester.

Table (average value of 30 pieces each) Figure 2 shows a multilayer ceramic capacitor based on the method of the present invention and a multilayer ceramic capacitor without adhesive impregnation treatment based on the conventional method (except for the adhesive impregnation treatment). This figure shows the moisture resistance characteristics when 50V is applied at 40° C. and 95% relative humidity (same as the method).

In FIG. 2, a shows the characteristics of the product of the present invention, and b shows the characteristics of the conventional product. As is clear from FIG. 2, it is clear that the moisture resistance of the multilayer ceramic capacitor based on the method of the present invention is extremely stable.

Incidentally, in the above embodiment, a porcelain dielectric material mainly composed of barium titanate, barium zirconate, and calcium titanate was used, but it goes without saying that other dielectric materials can also be misused. Furthermore, although the case where silver electrodes are provided at both ends has been described, -1-palladium alloy electrodes may also be used. In addition, although nickel plating and tin-lead alloy plating were explained in the examples,
Similar effects have been confirmed in plating other metals such as gold and palladium, and electroless plating is also effective.

Effects of the Invention As described above, the method of the present invention solves the problems that tend to occur in multilayer ceramic capacitors provided with plated electrodes, such as a decrease in the adhesion of the external electrode and unstable moisture resistance characteristics. can.

[Brief explanation of the drawing]

FIG. 1 is a -gi cutaway perspective view of a multilayer ceramic capacitor based on the method of the present invention, and FIG. 2 is a comparison diagram of the moisture resistance characteristics of multilayer ceramic capacitors based on the method of the present invention and the conventional method. (1)...Porcelain dielectric layer, (2)...Electrode layer ()(
1 radium electrode, (3)...silver electrode, (4)...
Nickel plating layer, (5)...Tin and lead alloy plating j- Agent, Yoshihiro Morimoto

Claims (1)

[Claims] 1. Silver or silver-palladium alloy electrodes are applied to both ends of a porcelain dielectric material in which tunic poles are stacked alternately in a comb shape, this porcelain dielectric material is impregnated with an anaerobic adhesive, and then the surface portion is A method of manufacturing a multilayer ceramic capacitor in which the electrodes at both ends are plated after removing excess adhesive from the capacitor.