JP3441350B2 - Piezoelectric resonator with built-in capacitance - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-mountable piezoelectric resonator with a built-in capacitor. 2. Description of the Related Art Conventionally, microcomputers and the like have been frequently used for communication equipment and electronic equipment, and a clock oscillation circuit has been connected to such a microcomputer. In this oscillation circuit, as shown in an equivalent circuit diagram of FIG. 5, input and output capacitance components C ₁ and C ₂ are connected between both ends of a piezoelectric resonance element R and a ground potential. The feedback resistance component r and the inverter I were connected between both ends. In order to easily achieve this oscillation circuit, the above-mentioned two capacitance components C ₁ and C ₂ are constituted by one capacitor element as shown by a dotted line in the figure, and this capacitor element and piezoelectric element are shown by a dashed line in FIG. The resonance element R and one electronic component are a built-in capacitance type piezoelectric resonator. [0004] The built-in capacitance type piezoelectric resonator has mainly been constituted by a piezoelectric resonance element having vibration electrodes formed on at least both main surfaces of a piezoelectric substrate and a capacitor element having two capacitance components. The following three structures are known as conventional exterior structures for protecting the piezoelectric resonance element and the capacitor element. A first structure is a piezoelectric resonance element in which vibration electrodes formed on both main surfaces are formed at the tips of two lead terminals, a split electrode is formed on one main surface, and the split electrode is opposed to the split electrode on the other main surface. A capacitor element having a ground electrode formed thereon is connected to each other, a third lead terminal connected to the ground electrode is further connected, and the outer peripheral resin is covered with an outer resin so as to form a vibration space. . The second structure is a structure in which a piezoelectric resonance element and a capacitor element are accommodated in an upper and lower two-part case.
Specifically, as disclosed in Japanese Patent Application Laid-Open No. 2-44706, a capacitor element is housed in one housing-like case, a piezoelectric resonance element is housed in the other housing-like case, and both cases are made of conductive paste. Were joined to each other. Further, as disclosed in Japanese Utility Model Application Laid-Open No. 62-70453, one case is formed as a flat dielectric substrate, and two capacitor components are formed on the dielectric substrate.
A piezoelectric resonance element was bonded to this dielectric substrate, and then the other housing-like case was bonded to one flat dielectric substrate so as to cover the piezoelectric resonance element. The third structure is such that both ends are open and two
A piezoelectric resonance element is arranged in a cylindrical dielectric case having a capacitance electrode forming two capacitance components, and both ends are sealed with a conductive cap body. In the first structure, it is difficult to surface mount on a printed wiring board. Further, in the second structure, the number of parts constituting the case increases, and a housing-like cover on the side for covering the piezoelectric resonance element to form a vibration space around the piezoelectric resonance element. It was necessary to make the shape of the case relatively large, and it was difficult to achieve a miniaturized piezoelectric resonator with a built-in capacitor. Further, in Japanese Patent Application Laid-Open No. 2-44706, it is necessary that a lead terminal led out to an external circuit has a conductive cap attached to both ends of the joined case or wound around the outer periphery of the case. It was very difficult to handle the terminals. In Japanese Utility Model Application Laid-Open No. 62-70453, 2
The external electrodes of the composite element in which the piezoelectric resonance element is connected to the dielectric substrate having two capacitor components must be led out from the joint surface between the dielectric substrate and the housing case.
This joining portion is a peripheral surface of the opening of the housing-like case having a relatively small joining area, and furthermore, the external electrodes must be led out, so that the joining reliability is reduced. In the third structure, when inserting the piezoelectric resonance element into the cylindrical case, the space on both main surfaces of the piezoelectric resonance element can be easily secured.
As in No. 06, it was necessary to cover the conductive caps at both ends of the cylindrical case, and it was very difficult to treat the lead terminals. Therefore, the applicant of the present application firstly changed a strip-shaped dielectric substrate having two capacitance components from a capacitor element,
We have proposed a built-in capacitor type piezoelectric resonator having a structure in which a laminate formed by laminating a strip-shaped piezoelectric resonator via a conductive adhesive is disposed in a housing-like case having at least one open side surface. More specifically, as shown in FIG. 6, a casing-like case 1 having one open side, a laminate 4 in which a strip-shaped piezoelectric resonance element 2 and a capacitor element 3 are joined, and a casing-like case And a sealing member for sealing the one opening 11. On the bottom surface 12 of the housing-like case 1, there are formed through holes 13 to 15 for connecting lead terminals to which a part of the lead terminals 16 to 18 is integrally fixed. The strip-shaped piezoelectric element 2 is
The vibrating electrodes 22 and 23 are formed on both main surfaces of the. The capacitor element 3 has a total of five electrodes formed on both main surfaces of the dielectric substrate 31. For example, capacitance electrodes 32 and 33 are formed at both ends of the upper main surface. Further, connection electrodes 34 and 36 are formed at both ends of the lower surface side main surface, and between the capacitance electrodes 32 and
A central capacitance electrode 35 facing a part of 33 is formed. The laminated body 4 is provided inside the housing case 1.
The stacked body 4 is housed and arranged with the capacitor element 3 of FIG. Thus, the through holes 13 to 13 on the bottom surface of the housing case 1 are formed.
Reference numerals 15 correspond to the connection electrode 34, the central capacitance electrode 35, and the connection electrode 36 formed on the lower main surface of the capacitor element 3, respectively, and the connection through holes 13 to 15 are filled with a conductive resin paste conductor. As a result, the lead terminals 16 to 18 are connected to the connection electrode 34, the central capacitance electrode 35, and the connection electrode 36. Here, the structure of the laminated body 4 is such that two capacitor electrodes 32 are provided at both ends of the upper main surface of the capacitor element 4.
33 are formed. Further, two connecting electrodes 3 are provided at both ends of the lower surface side main surface of the capacitor element which is the lower surface of the multilayer body 4
4 and 36, and one central capacitance electrode 35 are formed. On the main surface on the upper surface side of the piezoelectric resonance element 2, a vibrating electrode 22 on the upper surface side extending from the vicinity of the center to one end is provided.
In addition, an independent upper surface side auxiliary electrode 24 is formed at the other end. In addition, on the lower surface side main surface of the piezoelectric resonance element 2, a lower surface side vibrating electrode 23 extending from the vicinity of the center to the other end, and an independent lower surface side auxiliary electrode 25 formed at one end. ing. Then, the two elements are overlapped by the conductive bonding members 41 and 42 interposed at the ends of the bonding surfaces of the two elements to form a laminate 4. Further, conductive attachment members 43 and 44 formed by a thin-film technique or a thick-film technique are formed on the end faces of the laminate 4 respectively. The conductive members 43, 44
The capacitive electrodes 32, 33 on the upper surface of the capacitor element 3 and the connection electrodes 34, 36 formed on the lower surface are electrically connected, and in particular, one end of the piezoelectric resonance element 2 is connected to the conductive attaching member 44. Vibrating electrode 22 on the upper surface side
And one of the capacitor electrodes 33 of the capacitor element 3 (the connection electrode 3
6) are electrically connected. Note that the vibration electrode 23 on the lower surface side of the piezoelectric resonance element 2 is directly connected to the other capacitance electrode 32 on the upper surface side of the capacitor element 3 by the above-described conductive bonding member 41. Further, a gap corresponding to the thickness of the conductive bonding members 41 and 42 is formed between the piezoelectric resonance element 2 and the capacitor element 3 by the conductive bonding members 41 and 42. This gap becomes a vibration space on the lower surface side of the piezoelectric resonance element 2. The laminated body 4 composed of the piezoelectric resonance element 2 and the capacitor element 3 having the above-described structure is housed inside the case 1 through the opening 11 of the case 1. After that, the through hole 13 in the bottom surface 12 of the housing-like case 1
-15 are filled and supplied with a conductive filling member made of a resin paste containing silver powder. In order to simplify the arrangement of the laminated body 4 around the housing-shaped case 1 and the laminated body 4,
In order to stabilize the stable vibration operation, a gap of about 20 μm is formed. In such a state, the through hole 1
When the conductive paste is filled in 3 to 15, the conductive resin paste spreads in the gap between the bottom surface of the laminate 4 and the inner bottom surface of the housing case 11 due to the capillary phenomenon of the conductive resin paste. Then, the spread conductive paste reaches the adjacent electrode,
As a result, there is a problem that the lead terminals are short-circuited. The present invention has been devised in view of the above-mentioned problems, and an object of the present invention is to securely connect a conductor filled in a through hole in a bottom surface of a housing-like case and a connection electrode of a capacitor element. An object of the present invention is to provide a built-in capacity type piezoelectric resonator. According to the present invention, there is provided a housing-like case having a through-hole filled with a conductive connecting member on a bottom surface and opening at least one side surface; One end is connected to the conductive connection member, and the other end is a lead terminal leading out to the outer surface of the housing-like case, and a capacitor element having two capacitance components. A laminate having a connection electrode formed on the lower surface thereof, and a sealing member for sealing an opening of the casing-like case, wherein the laminate is housed and arranged in the casing-like case; In the piezoelectric resonator with a built-in capacitor, the lead terminal and a connection electrode of the laminate are connected via the conductive connection member, and an opening of a housing-like case is sealed with the sealing member. Table body connection electrode In a embedded capacitance piezoelectric resonator, characterized in that a conductive protrusion which is in contact with occluded and the conductive connecting member opening of the through hole provided in the housing-like casing. According to the present invention, the conductive projection is formed on the connection electrode formed on the lower surface side main surface of the capacitor element constituting the laminate. Then, when the laminated body is arranged in the housing-like case, the conductive protrusion is positioned so as to close the internal opening of the connection through hole on the bottom surface of the housing-like case. Therefore, even if the conductive resin paste serving as the conductive connection member is supplied into the through-hole, the conductive resin paste spreads in the gap between the lower surface of the laminate and the inner bottom surface of the housing case. And a short circuit with an adjacent connection electrode can be prevented. Further, even if the conductive resin paste is impregnated into the gap between the bottom surface of the housing-shaped case and the conductive projection formed on the lower surface of the laminate by the capillary effect of the conductive resin paste, the conductive resin paste is not impregnated. The spread of the conductive resin paste is limited only to the region of the conductive protrusion, and does not spread to a portion where the connection electrode is close to the bottom surface of the housing-shaped case, which is a gap corresponding to the thickness of the conductive protrusion. The preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an external perspective view of a built-in capacitor type piezoelectric resonator of the present invention, FIG. 2 is a sectional view thereof, and FIG. 3 is a perspective view of a laminated body. The built-in capacity type piezoelectric resonator has a housing-like case 1,
It mainly includes a laminate 4 in which a piezoelectric resonance element 2 and a capacitor element 3 are laminated, and a sealing member 5. The housing-like case 1 is made of a resin such as a liquid crystal polymer, and has, for example, an opening 11 on one short side surface. Further, through holes 13, 14, 15 for connecting lead terminals are formed in the bottom surface 12 of the case. Also, three lead terminals 16, 17, 18 are fixed to the outer surface of the case, and a part of each of the lead terminals 16, 17, 18 is fixed to the inner walls of the through holes 13, 14, 15 on the bottom surface. ing. The piezoelectric resonance element 2 includes a rectangular piezoelectric substrate 21.
And a vibration electrode 22 formed on the upper main surface and a vibration electrode 23 formed on the lower main surface. The piezoelectric substrate 21 is made of a piezoelectric ceramic material such as lead titanate (PT) or lead zirconate titanate (PZT), or a single crystal material such as quartz, lithium tantalate, lithium niobate, or lithium tetratrate. The vibrating electrodes 22 and 23 are formed so as to face each other near the center of both main surfaces of the piezoelectric substrate 21. The vibration electrode 22 extends from near the center of the upper surface of the piezoelectric substrate 21 to one end. An auxiliary electrode 24 is formed on the other end of the upper surface of the piezoelectric substrate 21. The vibrating electrode 23 extends from near the center of the lower surface of the piezoelectric substrate 21 to the other end. Piezoelectric substrate 2
Auxiliary electrode 25 is formed on one end of the lower surface of 1. The vibrating electrodes 22 and 23 and the auxiliary electrodes 24 and 25
Is formed of, for example, a thin-film conductor film mainly composed of an Ag-based material. The capacitor element 3 is made of PT (lead titanate), PZT (lead zirconate titanate), BaTiO ₃
A dielectric substrate 31 made of a dielectric ceramic material such as (barium titanate) and having the same planar shape as the piezoelectric substrate 21 described above, and a strip-shaped dielectric substrate 31, and capacitance electrodes 32 and 33 formed on the upper main surface. And connection electrodes 34 and 36 and a central capacitance electrode 35 formed on the lower surface side main surface. The capacitance electrodes 32 and 33 are formed from a central portion opposed to a part of the central capacitance electrode 35 formed on the lower main surface.
Each is led to a different end. For example, capacitance electrode 3
2 is led out from the vicinity of the center of the dielectric substrate 31 to the other end (the left end in the figure), and the capacitor electrode 33 is connected from the vicinity of the center to one end (the right end in the figure). Is derived. Thereby, the capacitance electrode 32 and the central capacitance electrode 3
5 and between the capacitance electrode 33 and the central capacitance electrode 35, respectively. The connection electrode 34, the central capacitance electrode 35, and the connection electrode 36 on the main surface of the lower surface of the dielectric substrate 31 are respectively formed with through holes 13, 14, 1, and 1 formed in the bottom surface 12 of the housing 1.
5 are formed. The piezoelectric resonance element 2 and the capacitor element 3 are joined via conductive joining materials 41 and 42, and constitute a laminated body 4 as a whole. The conductive bonding member 41 is disposed between the end of the vibration electrode 23 on the lower main surface of the piezoelectric resonance element 2 and the capacitance electrode 32 of the capacitor element 3. The conductive bonding member 42 is connected to the auxiliary electrode 25 on the lower surface side main surface of the piezoelectric resonance element 2 and the capacitor element 3.
Is arranged between the capacitor electrode 33 and the other. Further, a pair of end faces of the laminate 4, that is, a pair of short side end faces of the piezoelectric resonance element 2 and the capacitor element 3
Are provided on the pair of short side end surfaces.
Is attached. These conductive adhered members 43 and 44
A thick film technique, that is, coating and curing of a conductive resin paste, and a thin film technique, that is, a metal material such as silver or copper are applied by vapor deposition or sputtering. The upper surface-side vibrating electrode 22 of the piezoelectric resonance element 2, the capacitance electrode 33 of the capacitor element 3 (the conductive bonding member 42), and the connection electrode are formed by the conductive covering member 44 formed on one end surface of the laminated body 4. 36 is electrically connected. Further, the conductive adhered member 4 formed on the other end face of the laminate 4
3, the lower vibrating electrode 23 of the piezoelectric resonance element 1 and the capacitance electrode 32 of the capacitor element 3 (the conductive bonding member 4
1) The connection electrode 34 is electrically connected. The laminated body 4 in which the piezoelectric resonance element 2 and the capacitor element 3 are integrally joined as described above is housed and arranged inside the housing case 11 via the opening 11 of the housing case 1. . As a result, from the through holes 13, 14, 15 formed in the bottom surface 12 of the housing-like case 1, the connection electrode 34, the central capacitance electrode 35, and the connection electrode 36 formed on the lower surface side main surface of the capacitor element are respectively exposed. Will be. By arranging the conductive connecting members 61, 62, 62 in the through holes 13, 14, 15, the connecting electrodes 34 formed on the bottom surface of the capacitor element 3 are formed.
Is the lead terminal 16, and the center capacitance electrode 35 is the lead terminal 1.
7, the connection electrodes 36 are connected to the lead terminals 18, respectively, and the laminate 4 is fixed inside the housing-like case 1. Thereafter, a sealing member 5 such as an insulating resin is applied and supplied to the opening 11 of the housing-like case 1 and cured. Thereby, the inside of the housing case 11 is hermetically sealed, and the laminate is fixed to the housing case 1. In the above-described structure, each of the electrodes 34, 35 formed on the lower surface of the capacitor element 3 constituting the laminate 4
On the base 36, island-shaped conductive protrusions 34a, 35a, and 36a having a thickness of 20 to 50 μm are formed. The planar shape of the conductive protrusions 34a, 35a, 36a is
Are arranged in the housing case 1, the through holes 13 to 15
Has a shape that is large enough to close the opening on the inside. The conductive protrusions 34a, 35a, 36a
Can be formed before the capacitor element 3 and the piezoelectric resonance element 2 are joined, or can be formed after the capacitor element 3 and the piezoelectric resonance element 2 are joined. The conductive protrusions 34a, 35a, and 36a are achieved by selective printing of a conductive resin paste obtained by mixing silver powder and epoxy resin and curing by heat treatment at 180 ° C. Therefore, the connection electrodes 34 and 36 serving as bases and the central capacitance electrode 35
Can be formed without affecting the connection electrodes 34 and 36 and the central capacitor electrode 35 regardless of whether it is a conductor film formed by a thin film technique or a conductor film formed by a thick film technique. The conductive projections 34 a to 36 a project from the lower surface of the laminate 4. For this reason, when the laminated body 4 is stored and arranged inside the housing-like case 1, the protruding conductive protrusions 34 a, 35 a, 36 a come into contact with the inner bottom surface of the housing-like case 1. That is, the through holes 13, 14, and 15 have their internal openings completely closed by the conductive projections 34a, 35a, and 36a, and the through holes 13, 14, and 15 have concave shapes when viewed from the outside bottom surface. ing. The through-holes 13 and 1 having such a substantially concave shape are provided.
The conductive connection members 61, 62, 63 are filled in 4, 15 and are cured by heat treatment. Here, the conductive resin paste is applied to the through hole 1
3, 14 and 15, around the inner side opening, that is, the inner bottom surface of the housing case 1 and the conductive protrusions 34a, 35a and 36a.
Becomes difficult to spread to the portion where the abutment comes into contact. It is assumed that the inner bottom surface of the case 1 and the thick conductive films 34a, 34a,
Even if the conductive paste spreads in the minute gaps between the conductive protrusions 5a and 36a, the conductive protrusions 34a, 35a, and 36a have minute gaps in the portions where they are formed.
4a, 35a and 36a are not formed,
Since the conductive paste spreads sharply with an interval of 0 to 50 μm, the spread of the conductive paste due to the capillary phenomenon remains at the portions where the conductive protrusions 34a, 35a, and 36a are formed. In any case, the through holes 13, 14, 15
The conductive paste, which becomes the conductive connection members 61, 62, and 63, which are filled in, does not reach the adjacent connection electrodes 34, 36 and the central capacitance electrode 35 beyond the conductive protrusions 34a to 36a. The short-circuit phenomenon between the connection electrodes 34 and 36 and the central capacitance electrode 35 can be prevented. The above-mentioned conductive projections 34a to 36a
Is formed on the connection electrodes 34 and 36 and the central capacitance electrode 35 in a shape corresponding to the shape of the internal openings of the through holes 13 to 15, for example, in a substantially circular shape. However, the conductive protrusions 34a to 36a may close the internal openings of the through holes 13 to 15, and the cross sectional shape of the through holes 13 to 15 may be substantially concave. As shown in FIG.
As shown in the bottom view of the laminate 4 of FIG.
6b may be formed in an annular shape so as to close around the internal openings of the through holes 13 to 16. Further, in the above-described embodiment, the structure is such that two capacitance components are formed in the thickness direction of the capacitor element 3, and the capacitance electrode and the connection electrode are connected via the short side end surface of the dielectric substrate 31. The central capacitor electrodes are connected and formed independently, but three capacitor electrodes are formed around the long side of the dielectric substrate 31 so that a capacitor component is formed between adjacent capacitor electrodes. It does not matter. In this case, the capacitance electrode orbiting on the bottom surface may correspond to the through holes 13 to 15. According to the present invention, the conductive projection is formed on the connection electrode and the central capacitance electrode formed on the lower surface side main surface of the capacitor element constituting the laminate. In addition, the conductive protrusion is formed so as to close the internal opening of the through hole. Therefore, even if the conductive paste is filled to dispose the conductive connection member in the through-hole, the conductive paste does not enter the gap between the inner bottom surface of the housing case and the conductive protrusion. Even if the conductive paste impregnates the gap between the inner bottom surface of the housing-shaped case and the conductive protrusion due to the capillary phenomenon of the conductive paste, the inside of the housing-shaped case is not formed at the portion where the conductive protrusion is not formed. Since the distance between the bottom surface and the laminate is rapidly increased, the spread of the conductive paste due to the capillary phenomenon can also be suppressed in the conductive protrusions. After all, since the conductive paste for short-circuiting at least the adjacent connection electrodes and the center capacitance electrode does not occur on the lower surface of the capacitor element to be a laminated body, short-circuiting can be prevented, and the leads can be stably and reliably formed. The connection between the terminal and the electrode will be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an external perspective view of a built-in capacitor type piezoelectric resonator of the present invention. FIG. 2 is a cross-sectional view of a built-in capacitor type piezoelectric resonator of the present invention. FIG. 3 is a perspective view of the laminate of the present invention as viewed from the lower surface side. FIG. 4 is a bottom view of another laminate of the present invention. FIG. 5 shows an equivalent circuit diagram of a built-in capacitance type piezoelectric resonator. FIG. 6 is a cross-sectional view of a conventional built-in capacitance type piezoelectric resonator. [Description of Signs] 1 ··· Housing case 11 ··· Opening 12 ··· Bottom 13, 14 and 15 ··· Through-hole 2 ······ Piezoelectric resonance element 21 ··· ··· Piezoelectric substrates 22 and 23 ··· Vibrating electrode 3 ·········· Capacitor element 31 ··· Dielectric substrate 32 and 33 ··· Capacitance electrodes 34 and 36 ··· Connection electrode 35 ··· ······· Central capacitance electrodes 34a, 35a and 36a ··· Conductive protrusion 4 ····· Laminated bodies 41 and 42 ··· Conductive joining members 43 and 44 ··· 61 to 63: conductive filling member

Continuation of front page (56) References JP-A-4-373303 (JP, A) JP-A-8-107328 (JP, A) JP-A-5-83074 (JP, A) JP-A-60-123120 (JP) JP-A-60-256201 (JP, A) JP-A-10-190398 (JP, A) JP-A-10-303686 (JP, A) JP-A-10-335969 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H03H 9/00-9/24

Claims (1)

(57) [Claim 1] A housing-like case having a through-hole filled with a conductive connecting member on a bottom surface and having at least one side surface opened, and one end provided with the conductive hole. A piezoelectric resonance element is joined via a conductive joining member to a lead terminal connected to the conductive connection member and the other end leading to the outer surface of the housing-like case, and a capacitor element having two capacitance components. ,
And a sealing member that seals an opening of the housing-shaped case, wherein the stacked body is housed and arranged in the housing-shaped case, and the lead terminal and the lead terminal are connected to each other. In the piezoelectric resonator with a built-in capacitor, the connection electrode of the laminate is connected via the conductive connection member, and the opening of the housing case is sealed with the sealing member.
On the surface of the connection electrode of the laminate, close the opening of the through hole provided in the housing-like case and come into contact with the conductive connection member.
A piezoelectric resonator with a built-in capacitor, comprising a conductive protrusion.