JPH0770411B2 - Chip electronic component manufacturing method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a chip electronic component used for direct mounting on a printed wiring board.

Configuration of Conventional Example and Its Problems Chip resistors and chip type multilayer ceramic capacitors are generally well known as representatives of chip electronic components. For the terminal electrodes of these chip electronic parts, apply an alloy paste of silver and palladium to the terminal parts of the element body, and
Although many of them were baked in the past, the soldering temperature conditions for direct mounting on the printed wiring board are
As the temperature increased and solder leaching occurred frequently, recently, after applying and baking silver paste on the terminal part of the element body, nickel or copper plating is spread on the surface of the baked silver, and tin or Solderable alloy plating of tin and lead has been applied to produce chip electronic components that do not cause solder erosion.

However, the chip electronic component plated as described above has the above-mentioned excellent features, but on the other hand, strict plating treatment conditions are required in manufacturing. That is, the plating may grow not only on the silver part provided on the terminal part but also on the element part due to the plating process with a large current density or the plating process for a long time. Since there are some that occur in some cases, the plating treatment conditions may be naturally limited to low current density and short time. In this case, the plating thickness will be an extremely thin film on the order of microns, so if the current density is too low and the treatment is performed for a short time, the throwing power of the plating will deteriorate, and therefore the solderability will be poor. Sometimes it got worse. This phenomenon mainly depends largely on the components contained in the element body, and therefore it is necessary to make the range of the plating treatment condition extremely narrow depending on the type of the element body. Under such a critical condition, when 100 to 300,000 pieces are plated at the same time, it is unavoidable that the plating grows on the element body at a rate of several percent. Therefore, strict selection is required.

OBJECT OF THE INVENTION The present invention aims to remove the plating that has grown on the element body.

To achieve this object, the present invention removes the plating grown on the element body by heat-treating the plated chip electronic component at a temperature at which it is soldered.

Description of Embodiments Hereinafter, the present invention will be described in detail based on embodiments.

As a terminal electrode of a monolithic ceramic capacitor, a silver paste was first applied to the terminal portion, baked at 820 ± 20 ° C., electroplated with nickel, and then an alloy plating of tin and lead was applied thereon. The thus-obtained monolithic ceramic capacitors were observed with a stereoscopic microscope at a magnification of 20 times, and 100 monolithic ceramic capacitors with plating grown on the element body as shown in FIG. 3 were taken out. In the figure, 4 is a body
Is silver, 6 is nickel plating, 7 is tin-lead alloy plating,
Reference numeral 8 is a plated growth portion. The weight of 100 pieces is about 2 g, which is 50 times the weight, that is, 100 g of the laminated ceramic capacitors are immersed in zirconia heated to a soldering temperature of 200 to 250 ° C. did.

As a result, as shown in FIG. 1, when the heat treatment for 5 to 30 seconds was performed, the nickel plating 3 and the tin-lead alloy plating 4 were cut along the boundary between the element body 1 and the silver 2. Cage,
No plated growth was observed on the surface of the element body 2. Furthermore, the surface gloss was good, and the solderability was also very good.

The following table shows a comparison of other heat treatments with the heat treatment of the present invention. As is clear from this table, it can be said that the present invention is excellent in all of the effect of removing the growth of the plating on the element body, the solderability, and the gloss condition of the terminal electrode.

Further, FIG. 2 is a diagram showing the optimum values of the heat treatment temperature and the treatment time under the treatment conditions of the present invention. As can be seen from this figure, 220 ± 20 ° C and 5 to 25 seconds are the optimum conditions.

As described above, according to the present invention, after nickel-plated on the terminal electrode mainly composed of silver of the chip electronic component and further solderable alloy plating on the terminal electrode, 200-2
The heat treatment is performed through a heat medium heated to 50 ° C. When the heat treatment is performed at the above temperature, it is possible to easily and surely remove the plated growth portion that has grown to the chip electronic component element body to eliminate short circuit defects. Not only that, the surface of the alloy plating also has good solderability, and since the heat treatment temperature is a low temperature treatment of about 200 to 250 ° C, such as soldering, there should be little thermal influence on the chip component element, etc. Can be done.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional perspective view showing the chip electronic component after removing the plating grown on the chip electronic component body by the method of the present invention, and FIG. 2 is the optimum temperature and processing time in the method of the present invention. FIG. 3 is a partial cross-sectional perspective view showing the state of a conventional unprocessed chip electronic component, which shows the condition. 1 ... Element, 2 ... Silver, 3 ... Nickel plating, 4 ...
Alloy plating.

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Claims (1)

[Claims] 1. A chip electron in which a terminal electrode mainly composed of silver is plated with nickel, and a solderable alloy is further plated thereon, and then heat treatment is carried out by passing through a heating medium heated to 200 to 250 ° C. Manufacturing method of parts.