JP3596268B2 - Nonlinear dielectric element - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-linear dielectric element that exhibits non-linear behavior in electric field-charge characteristics, such as a high-voltage pulse generating capacitor used in a high-intensity discharge lamp (HID lamp). The present invention relates to an improved nonlinear dielectric element.
[0002]
[Prior art]
Conventionally, the HID lamp has been used as a lamp for realizing high luminance. Some HID lamps of this type require a high-pressure pulse of about 1 to 4 kV at startup, such as a high-pressure sodium lamp or a metal halide lamp. Therefore, in order to generate a high voltage pulse, a capacitor having a non-linear characteristic is incorporated.
For example, Japanese Utility Model Application No. Hei 3-7774 discloses a nonlinear capacitor as described above. FIG. 3 shows the structure of this nonlinear capacitor.
[0003]
The capacitor 51 has a structure in which electrodes 53 and 54 are formed on both surfaces of a ceramic plate 52 made of barium titanate-based ceramic. Lead terminals 56 and 57 are bonded to the centers of the electrodes 53 and 54 via bonding materials 55a and 55b. As this bonding material, a heat-resistant bonding material such as a glass frit-containing Ag paste is used. For the bonding, the glass frit-containing Ag paste is applied to the center of the electrodes 53 and 54, and the lead terminals 56 and 57 are connected. This was done by contact and baking.
Also, insulating layers 58 and 59 are formed in a ring shape so as to cover the vicinity of the outer peripheral edges of the electrodes 53 and 54.
[0004]
[Problems to be solved by the invention]
In the conventional nonlinear capacitor 51 shown in FIG. 3, the lead terminals 56, 57 are joined to the electrodes 53, 54 by the joining materials 55a, 55b in accordance with the above-described method. By the way, in order to obtain sufficient bonding strength in this bonding, it is necessary to press the lead terminals 56 and 57 against the electrodes 53 and 54 to fix the contact position. Therefore, the jig is brought into contact with the rear side of the flanges 56a, 57a provided at the tips of the lead terminals 56, 57, and the lead terminals 56, 57 are pressed into contact with the central joining positions of the electrodes 53, 54.
[0005]
However, with the above-mentioned pressing, the joining materials 55a and 55b before baking protrude outside from the interface between the flanges 56a and 57a and the electrodes 53 and 54, and wrap around from the side surfaces of the flanges 56a and 57a to the back surface, and the jig is attached. May adhere.
[0006]
As a result, the jig and the lead terminals 56 and 57 may be joined, or the jig may be contaminated by extra joining materials 55a and 55b.
Further, since the lead terminals 56 and 57 are usually made of a thin metal wire, when the lead terminals 56 and 57 are fixed to the joining position using a jig, the lead terminals 56 and 57 are likely to be deformed or misaligned due to the deformation. Was.
[0007]
An object of the present invention is to easily perform a joining operation of a lead terminal to an electrode, to prevent erroneous joining between a jig and a lead terminal by a joining material, and to ensure that the lead terminal is in a correct position on the electrode and has sufficient strength The object of the present invention is to provide a non-linear dielectric element which is joined by the following.
[0008]
[Means for Solving the Problems]
The nonlinear dielectric element according to the first aspect of the present invention includes a ceramic plate made of dielectric ceramic, first and second electrodes formed on first and second surfaces of the ceramic plate, respectively. A first and a second lead terminal bonded to the second electrode via a conductive bonding material solidified by baking, wherein the first and second lead terminals are connected to the first and second electrodes. A first flange portion having a diameter larger than that of the lead terminal main body portion and an opposite end of the first and second electrodes from the first flange portion are formed at an end joined to the first electrode. have a second flange portion, said first and second lead terminals is made of metal wire, and first, second flange portion, characterized in that it is formed by header processing.
[0009]
In the invention described in claim 2 , the first and second lead terminals are joined to the first and second electrodes at positions facing each other via a ceramic plate.
[0010]
According to the third aspect of the present invention, the bonding material is made of a glass frit-containing conductive bonding material.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be clarified by giving non-limiting examples of the present invention with reference to the drawings.
[0012]
FIG. 1 is a longitudinal sectional view showing a nonlinear dielectric element according to one embodiment of the present invention. The nonlinear dielectric element of this embodiment is suitably used as a capacitor for generating a high-voltage pulse in an HID lamp. However, the nonlinear dielectric element 1 is not limited to the above-mentioned application, but can be used as a pulse generation capacitor for various applications.
[0013]
As shown in FIG. 1, the nonlinear dielectric element 1 is configured using a disc-shaped ceramic plate 2. The ceramic plate 2 is made of a dielectric ceramic. As the dielectric ceramic that can be used, an appropriate dielectric ceramic having a so-called non-linear characteristic showing hysteresis in electric field-charge characteristics can be used. Barium-based ceramics are used.
[0014]
A first electrode 3 is formed on an upper surface 2a of the ceramic plate 2, and a second electrode 4 is formed on a lower surface 2b.
In this embodiment, the electrodes 3 and 4 are formed by applying and baking an Ag-Pd paste. However, the material constituting the electrodes 3 and 4 is not particularly limited, and other metals and alloys such as Ag and Cu can be used. The electrodes 3 and 4 may be formed by other forming methods such as vapor deposition, plating, and sputtering.
[0015]
Also, the planar shape of the ceramic plate 2 and the electrodes 3 and 4 is not limited to a disk shape, but may be another shape such as a quadrangle. Further, the electrodes 3 and 4 are preferably smaller than the planar shape of the ceramic plate in order to increase the withstand voltage.
[0016]
The insulating layers 5 and 6 are formed so as to cover the vicinity of the outer periphery of the electrodes 3 and 4. In the present embodiment, the insulating layers 5 and 6 are formed by printing a ferroelectric crystallized glass in a ring shape and baking it. However, it is not always necessary to use ferroelectric crystallized glass. For example, the insulating layers 5 and 6 may be formed by applying and baking a ceramic slurry mainly composed of dielectric ceramics.
[0017]
By forming the insulating layers 5 and 6, undesired discharge between the electrodes 3 and 4 can be prevented, and the withstand voltage can be increased.
First and second lead terminals 9 and 10 are bonded to the centers of the electrodes 3 and 4 via bonding materials 7 and 8, respectively. The first and second lead terminals are joined to the centers of the electrodes 3 and 4 so as to face each other with the ceramic plate 2 interposed therebetween.
[0018]
In the present embodiment, the lead terminals 9 and 10 are made of a Ni wire, and a first flange portion having a larger diameter than the lead terminal bodies 9a and 10a is provided at an end on the side to be joined to the electrodes 3 and 4. 9b and 10b are formed. The first flange portions 9b and 10b are provided to increase the bonding area of the bonding materials 7 and 8 and to firmly bond the lead terminals 9 and 10 to the electrodes 3 and 4.
[0019]
Further, second flanges 9c and 10c are formed so as to be separated from the first flanges 9b and 10b in a direction away from the electrodes 3 and 4. The second flanges 9c, 10c are configured to have a larger diameter than the lead terminal bodies 9a, 10a. The second flange portions 9c and 10c constitute a portion where the jig contacts when the lead terminals 9 and 10 are pressed against the electrodes 3 and 4 and joined. That is, the jig is brought into contact with the back surface of the second flange portions 9c, 10c (the back surface is the surface opposite to the electrodes 3, 4), and the lead terminals 9, 10 are brought into contact with the electrodes 3, 3. By pressing to the side 4, the first flange portions 9 b, 10 b can be pressed against the electrodes 3, 4 via the bonding materials 7, 8.
[0020]
In the present embodiment, a glass frit-containing Ag paste is used as the bonding materials 7 and 8. However, as long as it is solidified by baking, for example, another conductive bonding material such as an Ag-Pd alloy paste may be used.
[0021]
At the time of joining, as shown in FIG. 2, joining materials 7 and 8 are applied to the centers of the electrodes 3 and 4. On the other hand, lead terminals 9 and 10 are set in dies 11 and 12 as jigs. The mold 11 constitutes a lower mold and has a concave portion 11a opened upward. A through hole 11b is formed in the bottom surface of the concave portion 11a, and the lead terminal 10 is inserted into the through hole 11b. The diameter of the through hole 11b is smaller than the diameter of the second flange 10c. Therefore, as shown in the figure, the lead terminal 10 is locked in a state where the back surface of the second flange portion 10c is in contact with the bottom surface of the concave portion 11a of the mold 11, which is a jig.
[0022]
The non-linear dielectric element 1 on which the bonding materials 7 and 8 are applied is placed in the recess 11a. Thereafter, the lead terminal 9 is lowered together with the mold 12. The mold 12 has a through hole 12c penetrating the upper surface 12a and the lower surface 12b. The diameter of the through hole 12c is smaller than the diameter of the second flange 9c of the lead terminal 9.
[0023]
By bringing the molds 11 and 12 close to each other, the rear surfaces of the second flanges 9c and 10c of the lead terminals 9 and 10 are pressed by the molds 11 and 12, and the first flanges 9b and 10b are joined to the joining material 7 by the molds 7 and 8. , 8 are pressed against the electrodes 3,4. In this state, the lead terminals 9 and 10 can be joined to the electrodes 3 and 4 by heating the whole to the baking temperature of the joining materials 7 and 8.
[0024]
By the way, at the time of the joining, the back surfaces of the second flanges 9c, 10c contact the molds 11, 12, which are jigs, but the first flanges 9b, 10b to which the joining materials 7, 8 are directly contacted. Does not contact the molds 11 and 12. Therefore, when the first flanges 9b and 10b are pressed against the electrodes 3 and 4 side, even if the surplus bonding material is wrapped around the first flanges 9b and 10b on the back side, the wrap-around bonding is performed. The material does not adhere to the dies 11 and 12.
[0025]
Therefore, there is no possibility that the molds 11 and 12 are erroneously joined to the lead terminals 9 and 10. In addition, since the surplus bonding material does not adhere to the molds 11 and 12, it can be seen that it can be suitably used for sequentially bonding the lead terminals 9 and 10 to a large number of nonlinear dielectric elements.
[0026]
The distance A (see FIG. 1) between the front surfaces of the second flange portions 9c and 10c and the back surface of the first flange portions 9b and 10b is not particularly limited, but is 0.1 mm. It is desirable to make the above. When the distance A is less than 0.1 mm, the second flanges 9c and 10c are too close to the first flanges 9b and 10b, and the joining material that has protruded by the pressure welding is applied to the first flanges 9b and 10b. Of the second flanges 9c and 10c as well as the back of the second flange 9c.
[0027]
However, since the distance A varies depending on the type and viscosity of the joining material to be used, the viscosity, the force for pressing the lead terminals 9 and 10 against the electrodes 3 and 4 and the area of the flanges 9b and 10b, the distance A is uniquely determined. I can't get it. Also, if the distance A between the front surfaces of the second flange portions 9c, 10c and the back surface of the first flange portions 9b, 10b is too large, depending on the material and diameter of the lead terminals 9, 10, the second When the flanges 9c, 10c are pressed toward the electrodes 3, 4 by the dies 11, 12, the lead terminals 9, 10 may be deformed between the first and second flanges 9b, 9c and between 10b, 10c. is there. Therefore, the distance A is desirably 20 mm or less.
[0028]
According to an experiment conducted by the inventor of the present invention, Ag-Pd electrodes 3 and 4 having a diameter of 16 mm were formed on both surfaces of a disc-shaped ceramic plate 2 made of barium titanate having a diameter of 18 mm and a thickness of 1 mm, and ferroelectric crystallization was performed. The glass is printed in a ring shape having an outer diameter of 17 mm and an inner diameter of 14 mm, and is baked to form an insulating layer 5, 6 from the first flanges 9 b, 10 b and 2 b having a diameter of 2 mm. Bonding that has second flange portions 9c and 10c having a diameter of 2 mm at a position separated by a distance of 1 mm and lead terminals 9 and 10 made of a Ni wire having a body portion diameter of 0.5 mm and containing 3% by volume of glass frit. When they were set in the dies 11 and 12 using the materials 7 and 8 and baked at 500 ° C., adhesion of the bonding material to the dies 11 and 12, poor displacement of the lead terminals 9 and 10 and poor bonding strength were remarkable. It was confirmed that it could be reduced
[0029]
For comparison, the conventional non-linear capacitor 51 shown in FIG. 3 was manufactured with the same specifications as the above-mentioned embodiment without using the lead terminals 9 and 10. Poor bonding strength occurred at a rate of about 60%.
[0030]
The features of the present invention reside in the structure of the lead terminals 9 and 10 and the joints to the electrodes 3 and 4 by the joining materials 7 and 8. Can be changed as appropriate. For example, the insulating layers 5 and 6 may be formed so as to cover not only the vicinity of the outer peripheral edge of the electrodes 3 and 4 but also the entire periphery of a portion to be joined by the joining materials 7 and 8.
[0031]
【The invention's effect】
In the nonlinear dielectric element according to the first aspect of the present invention, the first and second lead terminals are joined to the first and second electrodes via a heat-resistant joining material. A first flange portion having a diameter larger than that of the lead terminal body portion, and a second flange portion formed so as to be separated from the first flange portion on a side opposite to the first and second electrodes. Therefore, the first and second electrodes are firmly joined to the first and second electrodes with a relatively large area by the front surface of the first flange portion, and the jig abuts on the rear surface of the second flange portion. Since the lead terminal is pressed against the electrode, even if the bonding material before solidification reaches the back surface of the first flange portion, it does not reach the back surface of the second flange portion. Therefore, the jig to be used and the lead terminal are not erroneously joined by the bonding material, and the used jig can be repeatedly used for manufacturing a large number of nonlinear dielectric elements without any trouble.
[0032]
Moreover, since the first and second flanges are provided on the lead terminal, the mechanical strength is increased even when the wire diameter of the lead terminal is small. This can be effectively prevented, and the lead terminal can be securely joined to a correct position, and the lead terminal can be firmly joined to the electrode.
[0033]
Therefore, in the conventional nonlinear dielectric element using a lead terminal having no second flange portion, a misalignment defect and a joint strength defect at the time of joining the lead terminals frequently occur. By providing the second flange portion, it is possible to eliminate such a positional deviation defect and a bonding strength defect, and to provide a nonlinear dielectric element having excellent reliability.
[0034]
In addition , since the first and second lead terminals are made of metal wires and the first and second flanges are formed by header processing, the first and second electrodes are connected to the first and second electrodes via a bonding material. , The second lead terminal can be reliably and electrically connected, and the first and second flanges can be easily and accurately formed into a desired shape by header processing. By providing the flange portion, it is possible to more effectively eliminate the above-described defective position of the lead terminal and defective bonding strength.
[0035]
According to the second aspect of the present invention, the first and second lead terminals are joined to the first and second electrodes at positions facing each other via the ceramic plate. Can be more effectively prevented from being displaced between the first and second lead terminals when the first and second electrodes are pressed against the first and second electrodes.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a nonlinear dielectric element according to one embodiment of the present invention.
FIG. 2 is a cross-sectional view for explaining a step of manufacturing the nonlinear dielectric element shown in FIG.
FIG. 3 is a longitudinal sectional view showing a conventional nonlinear dielectric element.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Nonlinear dielectric element 2 ... Ceramic plates 2a, 2b ... Upper and lower surfaces as first and second surfaces 3, 4 ... First and second electrodes 7, 8 ... Bonding material 9, 10 ... First, Second lead terminals 9a, 10a: lead terminal body portions 9b, 10b: first flange portions 9c, 10c: second flange portions 11, 12: mold as jig

Claims (3)

A ceramic plate made of dielectric ceramics,
First and second electrodes formed on first and second surfaces of the ceramic plate, respectively;
First and second lead terminals joined to the first and second electrodes via a conductive joining material solidified by baking,
The first and second lead terminals are connected at their ends to the first and second electrodes at a first flange portion having a diameter larger than that of the lead terminal body portion and a first flange portion extending from the first flange portion to the first flange portion. , and the second electrode have a second flange portion formed spaced on the opposite side, the first, second lead terminals made of metal wire, and first, second flange portion Is formed by header processing . The nonlinear dielectric element according to claim 1, wherein the first and second lead terminals are joined to the first and second electrodes at positions facing each other via a ceramic plate. The bonding material is a glass frit containing conductive bonding material, a non-linear dielectric element according to claim 1 or 2.

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