CN201425893Y - Ceramic capacitor - Google Patents

Abstract

The utility model discloses a ceramic capacitor, which comprises a body of the ceramic capacitor and a lead-out terminal of the capacitor. In the capacitor body, copper internal electrode layers are printed on the front and back sides of a sheet-shaped ceramic dielectric chip. Compared with the prior art, the inner electrode of the ceramic capacitor is a copper electrode, the cost of copper is much lower than that of silver, and the corresponding solder paste can also be a lead-free solder paste containing less silver or no silver. In addition, the inert copper ions will not migrate during the production and use of the capacitor. Therefore, the ceramic capacitor has high reliability and stability, low production cost of the product, and meets environmental protection requirements.

Description

A ceramic capacitor

technical field

The utility model relates to a ceramic capacitor, in particular to a ceramic capacitor with a changed inner electrode structure.

Background technique

At present, the traditional AC capacitor inner electrode material uses expensive silver paste. In the production and welding of finished disc ceramic capacitors, it is necessary to use expensive silver-containing solder to obtain a good welding effect. However, silver ions are relatively active and easily migrate. When traditional silver electrode capacitors work under high temperature or high voltage conditions, the water molecules infiltrated into the capacitor will undergo electrolysis, and an oxidation reaction will occur at the anode, and silver ions will combine with hydroxide ions to form silver hydroxide. A reduction reaction occurs at the cathode, and silver hydroxide reacts with hydrogen ions to form silver and water. Due to the electrode reaction, the silver ions in the anode are continuously reduced to the cathode to form discontinuous metal silver particles, which are connected by the water film to form a tree and extend to the anode. The migration of silver ions not only occurs on the surface of the inorganic medium, but also diffuses into the interior of the inorganic medium, causing an increase in leakage current. In severe cases, it can completely short-circuit the two silver electrodes, resulting in breakdown of the capacitor. In addition, the price of silver paste is very expensive. At the same time, silver as the internal electrode layer of the capacitor needs to be welded with silver solder paste to lead wires, and the capacity of the capacitor is drawn out from the lead wires. Therefore, the production cost of disc ceramic capacitors with silver inner electrodes is very high.

Utility model content

The technical problem to be solved by the utility model is to provide a ceramic capacitor with good product reliability and stability and low production cost.

The technical problem to be solved by the utility model is achieved through the following technical solutions: a ceramic capacitor, including a ceramic capacitor body and a lead-out terminal of the capacitor, and the capacitor body is printed on both sides of a sheet-shaped ceramic dielectric chip There is a copper inner electrode layer.

Further: in the copper inner electrode ceramic capacitor, the ceramic dielectric chip is one of a circular chip, a square chip, and an elliptical chip.

The capacity lead-out terminal is a lead wire welded on the outer side of the copper electrode layer with a solder layer. In order to further reduce the production cost, the solder layer is a low-silver or silver-free lead-free solder layer. The outer surface of the capacitor body is also provided with an epoxy resin or phenolic resin encapsulation layer to protect the body. The whole ceramic capacitor is in the shape of a disc.

Compared with the prior art, the internal electrode of the ceramic capacitor is a copper internal electrode layer. When the capacitor chip of the copper internal electrode is welded with the external electrode lead, the internal electrode metal copper will not dissolve in the solder (solder), that is, it will not occur. Flying copper (copper corrosion) phenomenon, so the solder joints inside the capacitor are more reliable. When producing and using this kind of capacitor, the inert copper will not migrate, so the reliability and stability of the product are better than that of the capacitor with silver internal electrodes. In addition, the price of silver is high, and an expensive silver solder paste layer is required when soldering lead wires. Therefore, the production cost of the copper electrode ceramic capacitor is low.

The above-mentioned ceramic capacitors are developed and selected through the development and selection of copper electrode paste, combined with the atmosphere firing process, and metal copper is used as the internal electrode of the disc ceramic capacitor. It goes through green molding, ceramic substrate sintering, copper paste printing, copper electrode sintering (need to use a suitable atmosphere), welding external leads, insulation encapsulation and testing to produce copper electrode disc ceramic capacitors. It uses the existing oxidizing atmosphere to sinter the ceramic substrate, and then uses an appropriate reducing atmosphere to sinter the copper electrode to make a copper electrode capacitor chip, and then uses cheap low-silver content solder to weld the capacitor, thus saving capacitor production Cost, but also improve the stability and reliability of the capacitor.

Description of drawings

Fig. 1 is a schematic diagram of the front half of the utility model embodiment;

Fig. 2 is a schematic longitudinal section of an embodiment of the utility model.

Among them: 1 ceramic dielectric chip, 2 copper inner electrode layer, 3 lead wire, 4 lead-free solder layer, 5 epoxy or phenolic resin encapsulation layer.

specific implementation plan

The utility model is described with reference to accompanying drawing 1～2 and specific embodiment.

A ceramic capacitor includes a body of the ceramic capacitor and lead-out terminals of the capacitor. The body of the capacitor is printed with copper inner electrode layers 2 on the front and back sides of a sheet-shaped ceramic dielectric chip 1 . In FIG. 1 , the ceramic dielectric chip 1 is in the shape of a disc, and it can also be one of a square chip and an elliptical chip. A lead wire 3 serving as a capacity lead-out terminal is welded on the outside of the copper internal electrode layer with a low-silver or silver-free lead-free solder layer. The outer surface of the capacitor body is also provided with an epoxy or phenolic resin encapsulation layer 5 to protect the body. The overall shape of the capacitor is disc shape.

Compared with the prior art, the inner electrode of the ceramic capacitor is a copper inner electrode layer 2. When the capacitor chip 1 of the copper inner electrode layer is welded with the external electrode lead 3, the inner electrode metal copper will not dissolve in the solder (solder), That is, there will be no flying copper (copper corrosion) phenomenon, so the internal solder joints of the capacitor are more reliable. When producing and using this kind of capacitor, the inert copper will not migrate, so the reliability and stability of the product are better than that of the capacitor with silver internal electrodes. In addition, the price of silver is high, and an expensive silver solder paste layer is required when soldering lead wires. When the copper inner electrode is soldered to the lead, a low-silver or silver-free solder layer is used. Therefore, the production cost of ceramic capacitors is low.

The above is a preferred embodiment of the utility model, and any obvious deformation and replacement without departing from the concept of the utility model shall fall within the protection scope of the utility model.

Claims (6)

1. A ceramic capacitor, comprising a body of a ceramic capacitor and a lead-out terminal of a capacitor, characterized in that: the capacitor body is printed with a copper inner electrode layer (2) on both sides of a sheet-like ceramic dielectric chip (1). ). 2. The ceramic capacitor according to claim 1, characterized in that: said ceramic dielectric chip (1) is one of a circular chip, a square chip, and an elliptical chip. 3. The ceramic capacitor according to claim 2, characterized in that said lead-out terminal is a lead wire (3) soldered to the outside of the copper electrode layer with a solder layer. 4. The ceramic capacitor according to claim 3, characterized in that the solder layer is a low-silver or silver-free lead-free solder layer (4). 5. The ceramic capacitor according to any one of claims 1-4, characterized in that: the outer surface of the capacitor body is provided with an epoxy or phenolic resin encapsulation layer (5) to protect the body. 6. The ceramic capacitor according to any one of claims 1-4, characterized in that: said ceramic capacitor is in the shape of a disc.

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