JPH04255206A - Ceramic capacitor and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain the title ceramic capacitor having excellent preciseness and quality by a method wherein a capacitor chip having the capacity which is a fraction that of a capacitor to be produced is roughly manufactured, and after it has been sorted, the sorted parts are properly assembled, and an electrode film is provided on the rear surface of the base plate in which the chip will be incorporated. CONSTITUTION:When the capacitance of a capacitor to be manufactured is 300PF, capacitor chips 1 are formed in the capacitance of 90 to 110PF, on the basis of 100PF which is 1/3 of the capacitance of the capacitor, when the maximum capacitance error is set at + or -10%. The capacitance of each chip 1 is measured, and the chips are classified into chips 1a of 108 to 110PF, 1b of 106 to 108PF, 1c of 104 to 106PF and the like, for example. The three of 1b (106 to 108PF), 1f (98 to 100PF) and 1j (92 to 94PF) are selected from chips 1a to 1j, for example, and when they are incorporated in parallel in a base plate, the capacitances become 296 to 302PF. Then, actual capacitance is measured, and if it is close to 302PF, a capacitor of 300PF can be obtained by using a base plate having a small area of an adjusting electrode film 23.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic capacitor with very little capacitance error and a method for manufacturing the same.

0002

2. Description of the Related Art Ceramic capacitors utilize a porcelain dielectric material, and in recent years, multilayer capacitors have been widely adopted due to the demand for smaller electronic components. This multilayer ceramic capacitor is made by printing a conductive film that serves as an internal electrode on a dielectric ceramic green sheet, stacking the sheets, pressing them together, cutting out a mold to have a predetermined capacitance, and firing it. A capacitor chip is formed by providing an external extraction electrode on the side surface of the laminated body to connect the internal electrode film, and then bonding the chip to a pair of electrode films formed on a base plate for mounting on a circuit. An external lead wire is connected to the external lead wire, and the other parts are molded with resin with the external lead wire protruding.

0003

[Problem to be Solved by the Invention] However, in the above-mentioned multilayer capacitor chips and non-multilayer capacitor chips, the capacitance is about 200PF due to the thickness of the dielectric ceramic and subtle differences in area during die cutting. This results in an error of about ±8%. This results in poor product yield and large tolerances in the capacitance of manufactured capacitors, which does not necessarily result in high-quality electronic parts. Therefore, the present invention proposes a means for efficiently producing a capacitor with little capacitance error.

0004

[Means for Solving the Problems] A ceramic capacitor according to the present invention has a pair of electrode films connected to external lead wires formed on the surface of a base plate, and a ceramic capacitor chip bonded between the electrode films of the base plate. , in a ceramic capacitor with external lead wires protruding and the rest entirely molded with resin, a predetermined number of capacitor chips with a capacity that is a fraction of the capacitor capacity to be manufactured are connected between the electrode films. This is characterized by the fact that an electrode film for fine adjustment of capacitor capacitance is formed on the back surface of the base plate.

[0005] Furthermore, in the method for manufacturing a ceramic capacitor according to the present invention, when manufacturing the capacitor, a plurality of capacitor chips are formed with a capacity that is a fraction of the capacitor capacity to be manufactured, and the capacitance error of each chip is eliminated. It is characterized in that the chips are measured and separated in advance, and the separated chips are appropriately combined and mounted on the base plate to obtain the desired capacity. The present invention is characterized in that a plurality of base plates are formed with adjusting electrode films having different areas, and a base plate that can obtain a desired capacitance is selected and used.

[0006]

[Operation] Even if there is an error of a few percent in the capacitance of a capacitor chip, a capacitor with a predetermined capacity can be obtained by combining capacitors with positive and negative errors. In addition, the adjustment electrode film on the back of the base plate forms a capacitance between the internal electrode film of the capacitor chip and the electrode film that connects the capacitor chip, and the overall capacitance of the capacitor depends on the area of the electrode film. fine adjustment is possible.

[0007]

[Embodiment] Next, an embodiment of the present invention will be explained in the case of a multilayer ceramic capacitor along with its manufacturing procedure. First, a laminated ceramic capacitor chip 1 is formed by printing an internal electrode film 12 on a dielectric ceramic green sheet 11 in the same way as in the past, and then laminating and press-bonding these sheets to a predetermined size. The laminate is molded and fired, and after sintering, external extraction electrodes 13 are provided on the sides of the laminate to connect with the electrode films 12 stacked alternately. When forming this capacitor chip 1, the capacitance of the capacitor to be produced is, for example, 30.
Assuming 0PF, the capacitor chip 1 is formed based on 100PF, which is one third of the capacitance. 100P
Assuming that the capacitance error is at most ±10%, the F ceramic capacitor chip 1 will be manufactured with a value of 110 to 90 PF. So 110~90PF chip 1
For example, chips 1a of 110 to 108 PF, chips 1b of 108 to 106 PF, and chips 106 of
Separate them into chips 1c with ~104PF...chips 1j with 92~90PF.

The base plate 2 into which the chip 1 is installed has a pair of electrode films 21 on the surface of which the chip 1 is bonded (using solder or conductive adhesive), and an external lead wire 22 connected to the electrode film 21. In addition, an adjustment electrode film 23 is provided on the back surface, and in particular, base plates 2a, 2b, . . . having different areas of adjustment electrode films 23 are formed. If you want to manufacture a capacitor with a capacity of 300PF, for example, 1b from between the separated chips 1a to 1j.
(108~106PF), 1f (100~98PF)1
If three of them (94 to 92 PF) are selected and they are installed in parallel on the base plate 2, the capacity will be 302 to 296 PF. Therefore, measure the actual capacitance, and if the value is close to 302PF, use a base plate with a small area of the adjustment electrode film 23, and conversely, if the value is close to 296PF, use a base plate with a large area of the adjustment electrode film 23. If a base plate is used, the capacitor produced will be 300PF. After the capacitor chips 1b, 1f, 1j are assembled into the base plate 2 in this manner, they are molded with resin 3 and used as electronic components.

[0009] Therefore, the capacitor chip 1 can be roughly formed, and by using it separately, more accurate capacitor parts can be obtained, and the capacitor chip 1 can be used without waste by appropriately combining it. Further, an electrode film 23 formed on the back surface of the base plate 2
By adjusting the area of , it is possible to make adjustments in units of 1 PF. Furthermore, since the capacitor chips are connected in parallel, the resonance sharpness Q is increased, and the sensitivity of the circuit using the product of the present invention is improved. It should be noted that the present invention is not limited to the above embodiments, and the capacitor chips may be of a non-stacked type, and furthermore, the number of chips to be incorporated into one capacitor and the range of sorting of chips can be arbitrarily determined. be.

0010

[Effects of the Invention] As described above, the present invention roughly produces capacitor chips having a capacity that is a fraction of that of the capacitor to be produced, and after separating them, combines them as appropriate.
In addition, an electrode film is provided on the back of the base plate into which the chip is installed, making it possible to provide high-quality products with good precision as capacitor parts without requiring special precision in manufacturing capacitor chips. It is.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a capacitor chip.

FIG. 2 is an explanatory diagram of manufacturing a capacitor component.

FIG. 3 is a side view of the capacitor component before resin molding.

FIG. 4 is an external view of a capacitor component.

[Explanation of symbols]

1, 1a, 1b...1j Capacitor chip 2 Base plate 21 Electrode film 22 External lead wire 23 Adjustment electrode film 3 Resin

Claims (4)

[Claims] Claim 1: A pair of electrode films to be connected to external lead wires are formed on the surface of a base plate, a ceramic capacitor chip is bonded between the electrode films of the base plate, and the external lead wires are made to protrude, and the rest of the entire body is A ceramic capacitor formed by resin molding, characterized in that a predetermined number of capacitor chips having a capacity that is a fraction of the capacitance to be produced are connected between electrode films. 2. A ceramic capacitor according to claim 1, characterized in that an electrode film for fine adjustment of capacitor capacity is formed on the back surface of the base plate. 3. An electrode film connected to an external lead wire is formed on the surface of the base plate, a ceramic capacitor chip is bonded between the electrode films of the base plate, the external lead wire is made to protrude, and the rest is molded with resin. In the ceramic capacitor formed by the above method, a plurality of capacitor chips are formed with a capacity that is a fraction of the capacitor capacity to be manufactured, the capacitance error of each chip is measured and classified in advance, and the classified chips are A method of manufacturing a ceramic capacitor, which is characterized in that it is assembled as appropriate and mounted on a base plate to obtain a desired capacitance. 4. According to claim 3, an adjustment electrode film is formed on the back surface of the base plate, and a plurality of base plates each having a different area of the adjustment electrode film are formed to obtain a desired capacitance. A method for manufacturing a ceramic capacitor, characterized by selecting and using a base plate capable of