JPS58121620A - 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 (a) Technical Field of the Invention The present invention relates to a method for manufacturing a multilayer ceramic capacitor, and particularly to a method for manufacturing a terminal electrode that has equivalent solderability and lower cost than conventional products.

(bl) Prior Art and Problems Multilayer ceramic capacitors, which are small, large-capacity, highly reliable, and have excellent high-frequency characteristics, have terminal electrodes at opposite ends of the capacitor element, which has internal electrodes laminated through a dielectric layer. Figure 1 is a cross-sectional view of a multilayer ceramic capacitor, which is made by firing and is composed of a capacitor element 2 and a pair of terminal electrodes 3 and 4.Generally, green sheet lamination method or green sheet printing is used. In the capacitor element 2if produced by the method, one internal electrode 6 and the other internal electrode 7 opposing it are formed in the dielectric layer 5, and one end of the internal electrode 6 is connected to the terminal electrode 3. On the other hand, one end of the internal electrode 7 is connected to a terminal electrode 4.The terminal electrodes 3 and 4 are made of an electrode paste made by mixing an appropriate amount of glassy powder with noble metal powder (for example, a mixed powder of silver and palladium). Although it is made by di-raging and then firing, it is necessary to have solder wettability for mounting on a single-capacitor hybrid integrated circuit board, etc.

Therefore, the conventional paste for terminal electrodes is made by adding 10 to 15 parts by weight of glassy powder to precious metal powder, and then kneading the mixture with an appropriate amount of organic binder and solvent.
K is set so that when the fired terminal electrode is immersed in a molten solder bath, the solder adheres to at least 915 seconds or 75 inches of the total electrode area. Therefore, in conventional multilayer ceramic capacitors, it is desirable to reduce the amount of precious metal in the electrode paste, make it cheaper, and increase the adhesive strength between the terminal electrode and the capacitor element, since the solderability is impaired. Just in case it can't be implemented.

(c) Purpose of the Invention The purpose of the present invention is to solve the above-mentioned problems, which is achieved by increasing the amount of glassy component and reducing the amount of precious metal.
In terminal electrodes fired using paste, more glass is precipitated on the electrode surface than in the inside, forming a film (DM).
This was done with the focus on the fact that the wettability of the coated layer is reduced due to the formation of a t-formed layer.

(a) Structure of the Invention The above object is achieved by providing a method for manufacturing a multilayer ceramic capacitor with a fine f% of firing and polishing a nine-terminal electrode using abrasive grains.

(s) Examples of the Invention The present invention will be explained below using actual measurement data related to Examples of the method of the present invention.

2nd ri! J relates to one experimental series of the method of the present invention and is 2.0×
4.5X1. Terminal electrodes are fired at opposite ends of a multilayer ceramic capacitor element having external dimensions of O-, and its solder wettability and solder erodibility are defined and are dangerous data,
The horizontal axis represents the time required for barrel polishing the terminal electrode, and the vertical axis represents the solder wettability and the number of solder eroded pieces. However, the number of samples (multilayer ceramic capacitors) under the same conditions was 20, and sample 1 had 5'
The solder erodibility was determined by immersion in a part of the terminal electrode (IPIi) that had been thinned by barrel polishing.
In detail, this is a phenomenon in which the silver in the electrode is not dipped into the molten solder, compared to when the silver in the electrode is dipped into the molten solder.

The spider electrode paste used is a noble metal powder consisting of 80 parts of silver and 20 parts of palladium, and a powder of a vitreous component whose main component is lead borosilicate glass (hereinafter referred to as glass powder).
After mixing, add an organic binder containing an appropriate amount of high-boiling point solvent to a colander and knead the mixture by adding 25% by weight and an appropriate amount of cross-mixing solvent to the total amount of the noble metal powder and glass powder, and then remove all the cross-mixing solvent from the evaporation source. It is made into a paste. Next, the amount of glass powder mixed was set at three levels: 20% by weight, 25% by weight, and 30% by weight of the noble metal powder, and the suitability of each was examined. In addition, the viscosity f of the various terminal electrode pastes is approximately 60.
The thickness of the terminal electrode, which was dipped onto a predetermined part of the sample and then heated and fired at approximately 850°C for 5 minutes, was 3005 m, which is close to the upper limit of uniform formation using this method.
That's about it.

On the other hand, several test samples of the same type with a barrel polishing lamp, a hard ball (alumina ball) with a diameter of about 300 f, and a diameter of about 20
Approximately 502 parts of 00 alumina abrasive and 25 parts of pure water
The diameter of the alumina pole and the mesh of the alumina abrasive are the constant values in column 9 in the 2nd WJ, using the conditions considered optimal from the barrel polishing experiment described later. (Average value of 20 items) The characteristics connected by all dotted lines are (terminal electrode paste containing 20% glass powder by weight) t11! Solderability of the terminal electrode used (-)
, the characteristics where the measured values are connected by the dashed line indicate the solderability of the terminal electrode using the paste for terminal electrodes containing 25% glass powder by weight (-), and the characteristics where the measured values are connected by the dashed dotted line indicate the solderability (-) of the terminal electrode using the paste for terminal electrodes containing 25% glass powder by weight. 30 Weight - This is the solderability of terminal electrodes using terminal electrode paste containing 0 indicating edibleness
As is clear from the figure, as the amount of glass powder mixed in increases, the ninth barrel time to obtain a desired solder wettability (for example, 9 to 1) requires a long time.
Since the range in which solder erosion does not occur is within 40 minutes of barrel time, the guaranteed barrel time range for the combination of solderability and solderability of 95 cm or more is when glass powder of 20 weight S is used. 30 for terminal electrode paste containing
OK, which takes ~40 minutes, whereas the terminal electrode paste containing 25 weight of glass powder takes 35 to 40 minutes;
Weight - base for terminal electrodes) Kilt does not exist. On the other hand, when the solder wettability is 75 inches or more,
For terminal electrode pastes in which the amount of glass powder mixed was 20 weight - 925 weight - 230 weight - the barrel ranges of quality guarantee were 10 to 40 minutes, 17 to 40 minutes, and 26 to 40 minutes, respectively. Note that if the solder wettability is 751 or higher, a glass powder T30 powder amount 3 pin electrode paste can also be used, but this is impractical when considering variations in the terminal electrode thickness and the amount of barrel polishing.

Figure 3 shows an example of experimental data for setting all the conditions for the barrel polishing, with the alumina ball diameter (4 levels) and the alumina abrasive mesh (3 water] 11k) as variable factors, and the barrel polished sample. When solder is dipped into the terminal electrode, the polishing time range in which the solder wettability is 95- and no solder erosion occurs is determined. However, the number of samples under each condition was 20, and samples with solder erosion were noted as disqualifying conditions.

In Figure 3, the smaller the alumina balls and the finer the alumina abrasive, the longer the barrel polishing time and the broader the time range. Using an alumina ball with a diameter of 2 mm and an alumina abrasive with a diameter of 1000 mm is unsuitable due to the possibility of solder erosion. The method of the present invention is considered to be an important process, and 9. and 1. 0.5~2■
It is desirable to use alumina balls with a diameter of 2,000 to 4,000 diameter and an alumina abrasive with a diameter of 2,000 to 4,000 diameter.

It should be noted that although alumina (ChttOs) was used as the abrasive in the nine-barrel polishing shown in FIG. 3, the same results could be obtained even if other types of abrasives (for example, silicon carbide, etc.) were used.

(0) According to the method of the present invention, as described in detail, the terminal electrodes of a multilayer ceramic capacitor are baked using an electrode paste containing a larger amount of glassy components than conventional ones, and then the terminal electrodes are polished and finished. , the solderability is activated to the same extent as that of terminal electrodes made using conventional electrode paste, so the paste used is inexpensive, and the adhesive strength between the capacitor element and the terminal electrode is increased. is a big 0

[Brief explanation of drawings]

Figure 1 is a fresh surface view of a multilayer ceramic capacitor, and Figure 2 is an experimental example of the method of the present invention, in which three types of terminal electrode pastes were used and fired, respectively. Figure 3 shows an example of measured data for determining the optimum conditions for barrel polishing, with the diameter of the ceramic ball and the mesh of the ceramic abrasive agent as variable factors. In addition, in the figure, 1 is a laminated ceramic container, 2 is
+2 capacitor element, 3.4 indicates terminal electrode 〇Hayabusa 1m 1 Figure 2 1 Maruno V separate row] Kiseki 3rd flash

Claims (1)

[Claims] (1) In manufacturing a multilayer ceramic capacitor in which a terminal electrode containing a glassy binder is fired at the end of a capacitor element, the terminal electrode is fired and then polished using abrasive grains. A method for manufacturing a multilayer ceramic capacitor characterized in that (2) the electrode paste forming the terminal electrode contains a vitreous component of 30% by weight or less of noble metal powder; i(]
) The manufacturing method of the multilayer ceramic capacitor described in section 2. (3) The above-mentioned polishing finish is barrel processing using a hard ball with a diameter of 0.5 to 2.0 mm and an abrasive with a particle size of φ2,000 to φ4,000 as described in item (1) of the patent encirclement. Manufacturing method for multilayer capacitors 0