JPH0316246Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Technical Field of the Invention] The present invention relates to a laminated ceramic varistor with an improved electrode structure. [Technical background of the invention and its problems] Multilayer ceramic varistors are generally small and have excellent surge resistance, and demand for them is likely to increase in the future. Conventionally, a commonly used multilayer ceramic varistor has a large number of internal electrodes 22 formed in layers between ceramic semiconductors 21, as shown in FIG. External electrode 2
3 and 24 are electrically connected in parallel. As a means for forming the laminated ceramic varistor constructed in this way, as shown in FIG. 9, a ceramic green sheet for varistor formed by a publicly known method is cut into a desired size. Internal electrodes 22 are printed and coated with an electrode paste containing an electrode material such as Au, Pt, Ag, or Pd, leaving a margin 26 on one side of the sheet body 25.
A plurality of ceramic semiconductors 21 are stacked so that the positions of the margin portions 26 are alternately on opposite sides, and the ceramic semiconductors 21 are stacked and crimped, and then sintered to be integrated. For example, the external electrodes 23 and 24 are formed by applying and baking a silver paste. However, in the laminated ceramic varistor configured as described above, alignment of the internal electrodes 22 is an important point, but for example, if misalignment occurs at the tip of the internal electrode 22 due to misalignment of the printing of the internal electrode 22, , the effective inter-electrode area becomes smaller accordingly, resulting in the inability to obtain the desired surge withstand capacity or energy withstand capacity, and in the sintering process, the external electrode 23,
Internal electrodes 22 to be exposed on both end faces forming 24
If the internal electrode 2 is not exposed enough, leave it as it is.
2 and the external electrodes 23 and 24 are in a non-contact state, the internal electrode 22 must be exposed by sand blasting or grinding after sintering, which requires a large number of man-hours.In addition, after forming the ceramic green sheet for varistor. Batch processing is required, resulting in poor workability.Furthermore, a sufficient margin 26 must be ensured to prevent inter-electrode shoots due to the external electrodes 23 and 24, which is an impediment to miniaturization. Ta. [Purpose of the present invention] The present invention has been made in view of the above points, and it is an object of the present invention to provide a highly reliable laminated ceramic varistor with a novel configuration that has good workability and can contribute to miniaturization or thinning. The purpose is to [Summary of the invention] The laminated ceramic varistor of the invention leaves an arbitrary part of both sides of one end in the length direction as a green sheet part, and forms a plurality of electrode parts alternately in a staggered manner on both sides starting from one side of the other end. Using a ceramic varistor sheet body formed with a ceramic varistor sheet body, a bent portion is provided at one end portion in the length direction of each of the electrode portions, and the raw sheet portion and the surface of the other end where the electrode portion is not formed are folded in a zigzag manner. stacked and integrated,
The invention is characterized in that the outer surface of the bent portion of the electrode portion serves as an external electrode. [Embodiment of the invention] An embodiment of the invention will be described below with reference to the drawings. That is, as shown in Fig. 2, a ceramic material containing zinc oxide, barium titanate, strontium titanate, silicon carbide, iron oxide, etc. as its main components, with several other metal oxides added and mixed, is used by extrusion method or Ceramic green sheet for baristas formed by doctor blade method etc. 1
An arbitrary part of both sides of one end in the length direction is left as the raw sheet part 2, and an arbitrary part of the other end (approximately the same area as the raw sheet part area) is alternately applied to both sides in a staggered manner as a starting point. Au, Pt, Cu, Ag, Pd,
Printing and applying electrode paste made of Ni etc.
Alternatively, a ceramic varistor sheet body 4 is obtained by vapor-depositing the electrode material to form a plurality of electrode parts 3. Using the sheet body 4, as shown in FIG. It is folded so that the opposite surface becomes the outer surface, and then sintered to form the first
As shown in the figure, the outer surface of the bent part 5 of the electrode part 3 is used as an external electrode 6, and an external terminal (not shown) is attached to the external electrode 7 as necessary. (not shown). The laminated ceramic varistor constructed as described above has a structure in which the electrode part 3 located inside by the zigzag folding becomes the internal electrode as it is, so there is no need to align the internal electrode, which is an important point, and it is different from the conventional method. The cause of characteristic deterioration due to the positional deviation of each internal electrode, which had occurred, is eliminated, and the conventionally required margin section 26 shown in FIG. 9 is no longer necessary, which contributes to miniaturization and thinning. In addition, since the structure is such that the electrode part 3 located on the outer surface of the bent part 5 provided by zigzag folding becomes the external electrode 6 as it is, there is no need to form a special external electrode, which not only simplifies the process but also reduces the risk of the conventional method. It is possible to completely ignore the problem of characteristic deterioration due to the non-contact state between the internal electrode and the external electrode, which had the same characteristics. Furthermore, the ceramic varistor sheet body 4 obtained by alternately forming a plurality of electrode parts 3 on both sides of the ceramic green sheet 1 for varistor in a staggered manner is simply folded according to the size of the electrode parts 4. It also has the advantage that it has better workability and is easier to automate than processes that involve processing, which greatly contributes to cost reduction. Next, the actual state of miniaturization or thinning according to the present invention will be described based on specific examples shown below. In other words, the main ingredient is zinc oxide, and the thickness of the molded product using the doctor blade method is 50 μm after baking.
Pt is used as the electrode material using a ceramic green sheet for varistors with a voltage of 10V and surge resistance of 50A to 100A.
The present invention (A) set at 200A and 400A, respectively,
As a result of examining the volumes of each of the conventional reference examples (B) shown in FIG. 8, the results are as shown in the table.

[Table] As is clear from the table above, there are differences depending on the surge withstand capacity, but the same surge withstand capacity of this invention
(A) can be made approximately 15 to 20% smaller in volume than the conventional reference example (B), demonstrating an effect that can greatly meet the market demand for smaller and thinner products. In the above embodiment, the case where the unit element is made singly was explained as an example, but as shown in FIG. By using a large ceramic varistor sheet 9 with a plurality of electrode parts 8 formed alternately in a staggered manner on both sides, folding it in a zigzag manner, crimping and sintering it, and then cutting it into the required size in the direction of the arrow, a large number of electrode parts 8 can be formed at once. This can greatly contribute to improving work efficiency. Further, in the above embodiment, the electrode portion is formed to the full extent on both sides, but if necessary, as shown in FIG. 5 and FIG. A ceramic varistat sheet body 13 is used, in which a blank portion 12 is provided at an arbitrary interval between both end faces in the width direction and between the electrode portions 11 so that a portion thereof is left as a green sheet portion 10 and an electrode portion 11 having an area necessary for forming an element is formed. , by zigzag folding, crimping, and sintering in the same manner as shown in FIG. 4, and cutting the center portion of the margin portion 12 in the longitudinal direction, a structure with a certain margin portion provided at both end portions can be obtained. I can do it. Furthermore, in the above embodiment, the thickness of the electrode part on the outer surface of the bent part which becomes the external electrode is the same as the thickness of the electrode part which becomes the internal electrode. In this case, the thickness of the electrode part on the outer surface of the bent part 15 of the electrode part 14 can be reduced by making the mesh rougher in that part, or by printing only that part twice, or in the case of vapor deposition, by depositing a larger amount in that part. Using a thick ceramic varistor sheet 16 is effective in increasing the strength of the external electrode. [Effects of the Invention] According to the present invention, it is possible to obtain a laminated ceramic varistor that is highly reliable, inexpensive, and of high industrial value, as well as contributing to miniaturization and thinning with good workability.

[Brief explanation of drawings]

1 to 3 relate to one embodiment of the present invention, FIG. 1 is a perspective view showing a completed laminated ceramic varistor, and FIG. 2 is a partially broken ceramic varistor configuring the structure shown in FIG. 1. A perspective view showing the sheet body, FIG. 3 is an explanatory diagram during manufacturing, FIG. 4 is an explanatory diagram during manufacturing according to another embodiment of the present invention, and FIGS. 5 and 6 are illustrations of other embodiments of the present invention. 5 is a perspective view, FIG. 6 is a side view, and FIG. 7 is a diagram showing a ceramic varistor sheet body according to another embodiment of the present invention, which is partially broken. FIGS. 8 and 9 are explanatory diagrams of a conventional reference example, and FIG. 8 is a perspective view showing a completed laminated ceramic varistor, and FIG. 9 is an explanatory diagram of the manufacturing process of FIG. 8. be. 1... Ceramic green sheet for barista,
2, 7, 10... Raw sheet part, 3, 8, 11, 1
4... Electrode part, 4, 9, 13, 16... Ceramic varistor sheet body, 5, 15... Bending part, 6...
...External electrode, 12...Margin area.

Claims (1)

[Claims for Utility Model Registration] (1) A plurality of electrode parts are formed alternately in a staggered manner on both sides, leaving an arbitrary part of both sides of one end in the length direction as a raw sheet part, and starting from one side of the other end. A bent portion is provided at one end in the length direction of each of the electrode portions, and the ceramic varistor is folded so that the green sheet portion and the surface opposite to the electrode portion formation at the other end are the outer surfaces. A laminated ceramic varistor characterized by sheet bodies that are folded and stacked to form an integrated structure. (2) The laminated ceramic varistor according to claim 1, which is characterized in that a blank space is provided at both widthwise ends of the ceramic varistor sheet body where the electrode portions are formed. (3) The laminated ceramic varistor according to claim 1 or 2, characterized in that the outer surface of the bent portion of the electrode portion serves as an external electrode. (4) The laminated ceramic varistor according to any one of claims 1 to 3, which is characterized in that only the portion of the electrode portion located on the outer surface of the bent portion is thickened.