Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-03-22
2001-07-03
Mayes, Curtis (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S089120, C156S278000, C427S123000, C029S025030
Reexamination Certificate
active
06254715
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for production of an electronic component having a terminal electrode.
2. Description of the Related Art
A typical electronic component having terminal electrodes is a stacked ceramic capacitor. To form the terminal electrodes of such a stacked ceramic capacitor, a capacitor element with stacked internal electrodes is produced, then an electrode paste is coated and dried on the two ends of the capacitor element.
Since it is difficult to coat an electrode paste simultaneously on the two ends of the capacitor element, normally the electrode paste is coated and dried on one end of the capacitor element to form a first end electrode, then the electrode paste is coated and dried on the other end of the element to form a second end electrode.
In this method of the related art, however, differences occurred in the shape of the first end electrode formed first at one end of the capacitor element and the shape of the second end electrode formed second and there was a tendency for the appearance to become unbalanced. In recent years, further, stacked ceramic capacitors have tended to be made increasingly smaller with sides of less than 1 mm. If an unbalance occurs in the shape of the two terminal electrodes, the distance between the two terminal electrodes may become narrower and cause sparks at the time of application of a test voltage, whereby the product will be judged defective and have to be disposed of even without any internal defects and consequently the manufacturing yield will fall. Further, if an unbalance occurs in the shapes of the two terminal electrodes, when mounting the stacked ceramic capacitor on the board, the problem will also arise of easier short-circuiting of the electrodes or mounting defects.
In particular, while the edge shape of the second end electrode formed second is relatively straight, the edge shape of the first end electrode formed first is wavy or rounded and there is a great variation in the dimensions of the edge shape. This has become a factor causing an unbalance in the shapes of the two terminal electrodes.
In the past, there has been no accurate recognition of the terminal electrodes. While various improvements have been made, none have been sufficiently effective.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a process for the production of an electronic component having a terminal electrode such as a stacked ceramic capacitor which reduces the variation in dimension of the edge shape of the terminal electrode and enables the production, with a high production efficiency, of electronic components improved in reliability and durability.
The present inventors engaged in intensive studies to achieve the above object and as a result noticed that the edge shape of the second end electrode formed second was relatively straight and discovered that the cause of this was that the element to be formed with the terminal electrodes had been heat treated by the drying step along with the silicone rubber holding the element before the step of coating the second electrode paste and thereby completed the present invention.
That is, according to a first aspect of the present invention, there is provided a process for production of an electronic component having a terminal electrode comprising a heat treatment step of heat treating an electronic component element to be formed with a terminal electrode in a state held by a rubber member, a coating step of coating an electrode paste on the heat treated element, and a drying step of drying the element coated with the electrode paste.
According to a second aspect of the present invention, there is provided a process for production of an electronic component having a terminal electrode comprising a heat treatment step of heat treating an electronic component element to be formed with first and second terminal electrodes in a state held by a rubber member, a first coating step of coating a first terminal electrode paste on a first end of the heat treated element, a first drying step of drying the element coated with the first terminal electrode paste, a second coating step of coating a second terminal electrode paste on a second end of the element, and a second drying step of drying the element coated with the second terminal electrode paste on the second end.
In the present invention, the rubber member is preferably comprised of a member comprised mainly of a silicone rubber. The rubber member is not particularly limited and may be any shape such as a sheet, block, etc., but preferably is a sheet-shaped rubber member formed with a plurality of through holes for holding elements. When coating the electrode paste on the end of an element, it is preferable to mount the element in a through hole so that the end of the element is exposed from the through hole. In the heat treatment step, the element may be heat treated buried completely in the inside of the through hole, but in the same way as when coating the electrode paste on the end of the element, it is also possible to heat treat the element in a state mounted in a through hole so that the end of the element is exposed from the through hole.
According to a third aspect of the present invention, there is provided a process for production of an electronic element having a terminal electrode comprising a heat treatment step of heat treating an electronic component element to be formed with a terminal electrode together with a silicone rubber, a coating step of coating an electrode paste on the heat treated element, and a drying step of drying the element coated with the electrode paste. In the process of production according to the third aspect of the present invention, the element and silicone rubber do not necessarily have to be in contact, but it is preferable that they be in contact.
According to a fourth aspect of the present invention, there is provided a process for production of an electronic component having a terminal electrode comprising an immersion step of immersing an electronic component element to be formed with a terminal electrode in a solution containing a silicone oil, a coating step of coating an electrode paste on the element next, and a drying step of drying the element coated with the electrode paste. In the process for production according to the fourth aspect of the invention, after the immersion step, it is preferable to dry the element, then perform the coating step.
In the processes of production according to the first to third aspects of the present invention, the heating temperature in the heat treatment step is preferably 80° C. to 300° C., more preferably 150° C. to 300° C., further preferably 180° C. to 250° C. The heat treatment time is preferably at least 2 minutes, more preferably 5.0 to 10.0 minutes. The heat treatment temperature in the heat treatment step may be about the same extent as the drying temperature in the drying step.
If the heat treatment temperature is too low, the advantageous effect of the present invention becomes smaller, while if the temperature is too high, the advantageous effects of the present invention increase a little and the work efficiency declines. Further, if the heat treatment time is too short, the advantageous effect of the present invention is small, while if the heat treatment time is too long, the production efficiency tends to fall. Note that the heat treatment step may be performed by the batch method or continuously. The means for conveying the rubber member holding the element is not particularly limited. A belt conveyor, conveyor roller, etc. may be employed.
The element is not particularly limited, but for example may be a capacitor element formed by alternately laminating an internal electrode layer and dielectric layer.
In the process for production according to the first aspect of the present invention, since the electrode paste is coated after heat treating the electronic component element to be formed with a terminal electrode in a state held by a rubber member
Greene Andy
Okazaki Mitsuo
Takekawa Ken
Mayes Curtis
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
TDK Corporation
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