JPH0831395B2 - Method for forming solder coating on external electrodes of chip-shaped electronic component - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming a solder coating on an external electrode provided on the outer peripheral surface of a chip-shaped electronic component such as a laminated ceramic capacitor or a chip resistor.

<Prior Art> Chip-shaped electronic components such as a monolithic ceramic capacitor are provided at both ends with external electrodes for forming a solder coating, which are connected to internal electrodes and the like. This external electrode is usually formed by applying an electrode paste made of an electrode material such as silver or palladium, glass frit, and a solvent to both ends of the chip-shaped electronic component and baking it under predetermined conditions.
Since the glass frit inevitably deposits on the surface of the external electrode thus formed, the solderability at the time of forming a solder coating on the external electrode becomes extremely poor. Therefore, in the past, a predetermined amount of chip-shaped electronic components was
Put the polishing media and water of a certain size in a container, and place the container on a pot rack and rotate it to polish the surface of the external electrode to remove the glass frit and then solder it on the external electrode. Forming a film is performed.

<Problems to be Solved by the Invention> However, in the above procedure, even if some glass frit can be removed, it cannot be removed enough to sufficiently improve the solderability, and further attempts are made to further improve the soldering. On the contrary, when the polishing time is extended, the solderability is deteriorated.

The present invention has been made in view of the above circumstances, and provides a method for forming a solder coating on an external electrode of a chip-shaped electronic component, which is capable of improving a conventional polishing method and forming a good solder coating. Is intended.

<Means for Solving Problems> In order to achieve such an object, the present invention provides a chip in which an external electrode for forming a solder coating, which is baked with an electrode paste containing glass frit, is provided on the outer peripheral surface. A method for forming a solder coating on an external electrode of a particulate electronic component, in which a chip-shaped electronic component on which the external electrode has been formed is put in a container together with a polishing medium, a predetermined amount of powder abrasive and a liquid such as water. After rotating the container for more than a minute, a solder coating is formed on the external electrodes of the chip-shaped electronic component taken out of the container.

<Operation> With the conventional polishing media having an outer diameter of about several mm, the surface of the external electrode cannot be uniformly polished and the glass frit cannot be sufficiently removed. By mixing the powder abrasive, the surface of the external electrode can be uniformly polished, the glass frit can be sufficiently removed to improve the solderability, and a good solder coating can be formed. You can do it.

<Example> Hereinafter, a method for forming a solder coating on an external electrode of a chip-shaped electronic component according to an example of the present invention will be described in comparison with a conventional method.

First, 100 sets are randomly picked from the same manufacturing lot of a monolithic ceramic capacitor, which is a chip-shaped electronic component to which external electrodes for forming a solder coating are provided, and 7 sets of such sets are formed. This monolithic ceramic capacitor has a length and width of 3.2 mm and a thickness of 2.5 mm. And 500c prepared in advance
Each of 100 sets of the monolithic ceramic capacitors of 6 sets among the 7 sets is housed in each of 6 containers of c. 2500cc of polishing media in which ones having an outer diameter of 1 to 6 mmφ are mixed together are housed in three of these six containers together with the monolithic ceramic capacitor,
Further, inject the required amount of water so that the water surface comes to the position of the eighth minute of the container. These three containers are group A.
In the remaining three of the six containers, 250 cc of polishing media in which the ones with an outer diameter of 1 to 6 mmφ are mixed together with the monolithic ceramic capacitor and the average particle size is 1
200 cc of powder abrasive such as 0 μ alumina is housed, and a required amount of water is injected so that the water surface comes to the position of the 8th minute of the container. These three containers are group B. That is, the A group is a conventional example and the B group is an example of the present invention. Then, place each of these three containers of group A and group B on the pot rack, and rotate the first container of each group for 30 minutes,
Rotate the 2nd container for 30 minutes and the remaining 3rd container 18
The outer electrodes of the monolithic ceramic capacitors are polished by rotating for 0 minutes. That is, in the present embodiment, the laminated ceramic capacitor, which is a chip-shaped electronic component with external electrodes formed and is placed in a container together with a polishing medium, a powder abrasive such as alumina, and water, is allowed to rotate the container for 30 minutes or more. It is accompanied by polishing. And
After discharging the monolithic ceramic capacitors of each container and drying the monolithic ceramic capacitors, the flux was adhered to each set of monolithic ceramic capacitors including the remaining set of 100 unpolished monolithic ceramic capacitors. Then, the solder coating is formed by immersing in the molten solder and applying solder on each external electrode.

The solderability of each set of laminated ceramic capacitors to which solder has been applied in this way is represented by the area ratio of defective solder attachments and the number of defective solders, which are shown in FIGS. 1 and 2, respectively. Here, the defective area ratio for soldering is the area ratio of the external electrodes of the individual monolithic ceramic capacitors of each set of 100, which are not attached to the solder, and is shown as the average value of 100 of them. . The number of defective solder attachments is defined as the defective product when the area ratio of the external electrodes of the external electrodes of the multilayer ceramic capacitors of each set is greater than 5%, and is shown as the defective number in 100 of each set. It is a thing. As is clear from FIGS. 1 and 2, the solderability is not sufficiently improved in the group A, which uses only the polishing medium, but the polishing medium is provided with a predetermined amount of the powder abrasive. In Group B, which has been added, the solderability is sufficiently improved.

The size and number of the monolithic ceramic capacitors housed in the container, the size and amount of the polishing media, the particle size and amount of the powder abrasive, and the like cause a difference in the polishing state depending on the rotation time (polishing time). The effect of using a powder abrasive is no different.
The powder abrasive may be other than alumina, and other liquid that does not affect the characteristics of the chip-shaped electronic component such as a monolithic ceramic capacitor may be used instead of water injected into the container.

<Effects of the Invention> As described above, according to the present invention, a chip-shaped electronic component provided with an external electrode for forming a solder coating on the outer peripheral surface together with a polishing medium, a powder abrasive, and a liquid such as water. Since it is polished by putting it in the container and rotating the container for 30 minutes or more, it is possible to sufficiently remove the glass frit deposited on the surface of the external electrode and improve the solderability. It is possible to obtain an effect that a good solder coating can be formed.

[Brief description of drawings]

Figure 1 shows the defective area of solder adhesion and rotation time (polishing time)
And FIG. 2 is a diagram showing the relationship between the number of defective solder adhesions and the rotation time (polishing time).

Claims (1)

[Claims] 1. A method of forming a solder coating on an external electrode of a chip-shaped electronic component, wherein an external electrode for forming a solder coating, which is baked with an electrode paste containing glass frit, is provided on the outer peripheral surface. Put the finished chip-shaped electronic parts together with the polishing media, the specified amount of powdered abrasive and liquid such as water into the container, rotate the container for 30 minutes or more, and then remove the chip-shaped electronic parts from the container. A method for forming a solder coating on an external electrode of a chip-shaped electronic component, which comprises forming a solder coating on the external electrode.