JP2007060214A - Piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric device having a structure contributing to miniaturization of the piezoelectric device, improving its assemblability and enabling its high function. <P>SOLUTION: Pattern electrodes 32a-32l forming a plurality of pairs are formed on one surface of a substrate 35 in which electrodes and wiring patterns are formed on both surfaces of a base material 31, and circuit elements 50a-50f corresponding to each of them are joined by solder junction, thereby obtaining a circuit module 30. External connection terminals 33a, 33b of the circuit module 30 are joined by solder to mount electrodes 3a, 3b formed on the concave bottom of a package body 1 corresponding to each of the terminals. Further, a piezoelectric resonation piece 20 is almost horizontally supported in cantilever by joining a connection electrode thereof to the mount electrodes 4a, 4b of the package body using a conductive adhesive 120. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a piezoelectric device in which a piezoelectric vibrating piece and other electronic components are joined in a planar arrangement in a package.

  Conventionally, a piezoelectric device including a piezoelectric vibrating piece has been used in various information / communication equipment, OA equipment, and electronic equipment such as consumer equipment. In recent years, in particular, in the field of small information devices such as mobile computers and IC cards, and portable communication devices represented by mobile phones, the progress of high functionality along with the downsizing and weight reduction of devices has been remarkable. Thus, the piezoelectric device has been reduced in size, thickness, and functionality. In order to increase the functionality of piezoelectric devices, for example, a crystal oscillation circuit as an example of a piezoelectric device is desired to include not only a crystal resonator element but also an oscillation circuit, a frequency adjustment circuit, a temperature compensation circuit, and the like. .

  As a piezoelectric device that meets the needs for such miniaturization / thinning and high functionality, a piezoelectric device is proposed in which a piezoelectric vibrating piece and other electronic components constituting a circuit are provided in the same package. That is, a package base having a recess is formed by laminating a ceramic base made of a flat plate and a rectangular annular ceramic, and a crystal plate as a piezoelectric vibrating piece is connected to a connection terminal (electrode) provided on the plane of the bottom of the recess (Crystal resonator element), a chip resistor and a chip capacitor as electronic components are respectively bonded by a conductive adhesive, and an IC is further bonded by wire bonding. Each connection terminal where the quartz plate and each electronic component are joined is electrically connected to the user terminal formed outside the bottom plate by a physically filled through hole provided in the bottom plate of the ceramic base. Yes. Furthermore, a cap (lid body) is joined to the upper surface of the ceramic base on which the above-described quartz plate and various electronic components are mounted, and the inside of the package is kept airtight (Patent Document 1). In addition to the above-described electronic component joining method using the conductive adhesive, joining by soldering is generally performed.

JP 11-274890 A

However, in the structure of the piezoelectric device described in Patent Document 1, when various electronic components are joined to the concave bottom portion of the package body, the side wall surrounding the package body becomes an obstruction factor and the workability is poor. For example, a needle part of a dispenser used when applying a conductive adhesive or solder paste, a nozzle of a chip mounter used when temporarily mounting an electronic component, a capillary of a wire bonder when wire bonding, etc. The workability was deteriorated by buffering on the side wall of the main body. For this reason, electronic components cannot be arranged near the side wall of the concave bottom portion of the package body, and there is a restriction that a certain dead space must be provided, which is disadvantageous for downsizing the piezoelectric device in the planar direction. There was a problem that.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a piezoelectric device having a structure that contributes to miniaturization of the piezoelectric device, improves assembling property, and can achieve high functionality. There is to do.

  In order to solve the above problems, in the present invention, a recess is formed, and a package body having a plurality of electrodes provided on a bottom plane of the recess, a piezoelectric vibrating piece, a plurality of electronic components, and a package body A lid that hermetically seals the inside of the recess, and a piezoelectric device having a structure in which the piezoelectric vibrating piece and the electronic component are bonded to the plurality of electrodes of the package body, the electronic component being bonded to the substrate, The main purpose is that the substrate is bonded to any one of the plurality of electrodes.

  According to this configuration, in the case of the conventional system in which the circuit element is directly mounted on the concave bottom portion of the package body, the arrangement of various circuit elements in the vicinity of the side wall where the side wall of the package body has become difficult as an obstacle is difficult. It becomes possible. As a result, various circuit elements can be mounted on the concave bottom portion of the package body in a space-saving manner, so that it is possible to reduce the size of the piezoelectric device, particularly in the planar direction. In addition, since various circuit elements can be mounted in a space-saving manner, it is possible to increase the functionality of the piezoelectric device while maintaining a small size. Furthermore, since the board on which the circuit element is mounted can be made versatile by designing the circuit wiring of the board, it can also be used for other types of piezoelectric devices, reducing the cost of manufacturing piezoelectric devices, It is possible to contribute to shortening the delivery time in mass production of new piezoelectric devices.

  In the present invention, it is desirable that the electronic component bonded to the substrate is resin-sealed.

  According to this configuration, the plurality of electronic components bonded to the substrate are sealed with the sealing resin and mounted on the concave bottom portion of the package body. Thereby, for example, when conductive foreign matter such as solder balls and solder scraps generated when the electronic component is joined to the substrate by soldering, the conductive foreign matter is transferred to the piezoelectric vibrating piece. In addition, it is possible to avoid a risk of adhering to the connecting portion and adversely affecting the vibration characteristics of the piezoelectric vibrating piece or causing an electrical short circuit. In addition, it is possible to avoid the risk of adversely affecting the vibration characteristics, etc., by adhering to the piezoelectric vibrating piece due to movement or vaporization of residues such as flux used for the substrate, electronic parts, and soldering. It becomes possible. Therefore, it is possible to provide a piezoelectric device having excellent vibration characteristics by the piezoelectric vibrating piece and having high reliability.

(First embodiment)
Hereinafter, a first embodiment of a piezoelectric device according to the present invention will be described with reference to the drawings.

  Fig.1 (a) is a front view explaining the structure of 1st Embodiment of the piezoelectric device of this invention, The same figure (b) is the AA cross section in Fig.1 (a) of the piezoelectric device. FIG. In FIG. 1 (a), the package lid covering the upper portion of the piezoelectric device is shown by imaginary lines and only the installation position is not shown.

  The piezoelectric device 10 includes a package body 1 having a recess having an upper surface opened. A plurality of circuit elements 50a to 50f, which are electronic components, are provided on a substrate 35 having a piezoelectric vibrating piece 20 made of quartz and a plurality of pairs of electrode terminals 32a to 32l provided on a base material 31 at the bottom of the package body 1. Are connected to each other to form an electric circuit. A package lid 2 is provided that seals the upper surface opening of the package body 1 to which the piezoelectric vibrating piece 20 and the circuit module 30 are joined as a top plate.

  A package main body 1 formed of a ceramic material such as alumina includes a rectangular flat plate-shaped bottom plate portion 1b and side wall portions 1a that are recessed on four sides of the bottom plate portion 1b. A plurality of mount electrodes 4 a and 4 b for joining the piezoelectric vibrating reed 20 and a plurality of mount electrodes 3 a and 3 b for joining the circuit module 30 are arranged in a plane on the bottom surface of the recess of the package body 1. Each of them is electrically connected by an internal wiring (not shown) provided on the bottom plate portion 1b. A part of the internal wiring is connected to a conductive through hole (not shown) formed in the bottom plate portion 1b, and the through hole is connected to an external connection terminal (not shown) formed outside the bottom plate portion 1b. Electrically connected.

The piezoelectric vibrating piece 20 has an excitation electrode (not shown) formed on the front and back surfaces of a rectangular thin plate made of quartz, and a pair of connection electrodes (not shown) drawn from the excitation electrode. The piezoelectric vibrating piece 20 is cantilevered substantially horizontally by positioning the corresponding connection electrodes on the mount electrodes 4a and 4b formed on the concave bottom portion of the package body 1 and bonding them with the conductive adhesive 120, respectively. Has been.
The connection method between the pair of connection electrodes of the piezoelectric vibrating piece 20 and the corresponding mount electrodes 4a and 4b of the package body 1 is not limited to a method using a conductive adhesive, but may be soldering or other methods. It may be used.

  The circuit module 30 includes a substrate 35 on which electrodes and wiring patterns are formed on both surfaces of an insulating base material 31 made of glass epoxy resin or the like by a method such as photolithography. On the upper surface side (main pattern formation surface 31a) of the substrate 35, a plurality of pairs of pattern electrodes 32a to 32l are formed. In the circuit module 30 of this embodiment, pattern electrodes 32a and 32b, 32c and 32d, 32e and 32f, 32g and 32h, 32i and 32j, 32k and 32l are formed in pairs. Circuit elements 50a to 50f corresponding to the respective electrode pairs are connected to the pattern electrodes 32a to 32l thus paired by solder (not shown). The circuit elements 50a to 50f include, for example, a chip resistor used for controlling the current value flowing through the circuit, a chip capacitor used for stabilizing the circuit voltage, a chip thermistor used for temperature correction of the operation of the piezoelectric vibrating piece 20, and the like. . On the other hand, external connection terminals 33 a and 33 b are formed on the other surface (back surface 31 b) of the substrate 35. The external connection terminals 33a and 33b are electrically connected to a wiring pattern (not shown) of the circuit module 30 to which the circuit elements 50a to 50f are connected by through holes having conductivity (not shown). The circuit module 30 includes the package body 1 by bonding the external connection terminals 33a and 33b and the mount electrodes 3a and 3b formed on the corresponding concave bottoms of the package body 1 with solder (not shown). It is fixed to.

  A package lid 2 is joined to the upper surface of the package body 1 to which the circuit module 30 and the piezoelectric vibrating piece 20 are joined via a seal ring 9 so that the inside of the package body 1 is kept airtight and sealed. .

Next, a method for manufacturing the piezoelectric device 10 will be described with reference to the drawings.
FIG. 2 is a flowchart of the manufacturing process of the piezoelectric device 10 of the present embodiment.

  In step S1, each circuit element 50a-50f is mounted on the substrate 31 by SMT (Surface Mount Technology), and the circuit module 30 is manufactured. In manufacturing the circuit module 30, first, a predetermined amount of solder paste is applied to the pattern electrodes 32a to 32l of the substrate 35 by a screen printing method. Next, the circuit elements 50a to 50f corresponding to the pattern electrodes 32a and 32b, 32c and 32d, 32e and 32f, 32g and 32h, 32i and 32j, 32k and 32l, respectively, which are paired, are obtained using a chip mounter or the like. Temporary mounting is performed for positioning at a predetermined position. Next, by heating the substrate 35 on which the circuit elements 50a to 50f are temporarily mounted in a reflow furnace or the like with a temperature profile considering the solder melting temperature, the solder is melted to join the circuit elements 50a to 50f. Let Then, the circuit module 30 is cleaned with a cleaning liquid made of an organic solvent or the like to remove flux contained in the solder paste, solder balls generated by solder reflow, and the like (step S2).

  In step S3, the circuit module 30 is inspected. In the inspection, it is determined whether or not the circuit elements 50a to 50f are properly joined by a method such as an appearance inspection and an electrical characteristic inspection (step S4). If a bonding failure of a circuit element is found (No in step S4), the corresponding part is corrected (step S13), and the circuit module cleaning process in step S2 is performed again. In addition, when the defect location discovered by step S4 will be in the state which cannot be corrected, it will be classified as a defect product.

  When it is determined in the inspection of the circuit module 30 that the circuit elements 50a to 50f are properly joined (Yes in step S4), the process proceeds to step S5 and the circuit module 30 is mounted on the package body 1. . First, a predetermined amount of solder paste is applied to the mount electrodes 3a and 3b of the package body 1 by a dispenser or the like, and then the external connection terminals 33a and 33b of the circuit module 30 are respectively connected to the mount electrodes 3a and 3b of the corresponding package body 1 respectively. Position and temporarily mount on 3b. Next, the package body 1 is heated by a reflow furnace or the like to perform solder bonding, and the mounting of the circuit module 30 is completed. Then, the package body on which the circuit module 30 is mounted is cleaned with a cleaning liquid made of an organic solvent or the like to remove contaminants such as flux and deposits (step S6).

  In step S7, a predetermined amount of conductive adhesive 120 is applied on the mount electrodes 4a and 4b of the package body 1, and the connection electrodes of the piezoelectric vibrating reed 20 are positioned on the corresponding mount electrodes 4a and 4b, respectively. The piece 20 is temporarily mounted so as to be substantially horizontal, and the conductive adhesive 120 is dried to fix the piezoelectric vibrating piece 20 and complete the mounting.

  In step S8, cleaning for the purpose of cleaning the piezoelectric vibrating piece 20 is performed with pure water or the like. Next, frequency adjustment is performed to adjust the frequency of the piezoelectric vibrating reed 20 electrically connected to the circuit module 30 via the package body 1 to a desired value (step S9).

  In step S10, baking is performed in which the package body 1 on which the piezoelectric vibrating piece 20 and the circuit module 30 are mounted is placed in a drying furnace at a predetermined temperature for a predetermined time to be dried. Subsequently, in step S11, a metal package lid 2 is joined to the upper surface of the package body 1 via a seal ring 9, and sealed so as to keep the inside of the package body 1 airtight. Device 10 is obtained.

  In step S12, an electrical property test is performed to confirm whether or not the electrical property of the piezoelectric device 10 is within a predetermined range, and a series of manufacturing steps of the piezoelectric device 10 is completed.

  Next, the effect of the said embodiment is described below.

  (1) In the above embodiment, the circuit module 30 is obtained by first joining the circuit elements 50 a to 50 f to be mounted on the concave bottom portion of the package body 1 of the piezoelectric device 10 together with the piezoelectric vibrating piece 20 to the substrate 35. Then, the circuit module 30 is configured to be joined to the mount electrodes 3 a and 3 b on the concave bottom portion of the package body 1.

According to this configuration, in the case of the conventional system in which the circuit elements 50a to 50f are directly mounted on the concave bottom portion of the package main body 1, the side wall portion 1a that has been difficult because the side wall portion 1a of the package main body 1 becomes an obstacle. Various circuit elements can be arranged in the vicinity. As a result, since the circuit elements 50a to 50f can be mounted on the concave bottom portion of the package body 1 in a space-saving manner, it is possible to reduce the size of the piezoelectric device 10 particularly in the planar direction.
Further, since the circuit module 30 can be provided with versatility by designing the circuit wiring of the substrate 35, it can be used for a different type of piezoelectric device. It is possible to contribute to shortening the delivery time in mass production of the product.

(2) In the above embodiment, when the circuit elements 50 a to 50 f are bonded to the substrate 35, the mounting method is adopted by SMT.
As a result, for example, a screen printing method can be applied to the application of the solder paste using a multi-piece substrate, so that efficient and high-quality circuit element mounting can be achieved, and the piezoelectric device 10 can be efficiently manufactured. It becomes possible to contribute to cost reduction. Moreover, since each circuit element 50a-50f is joined by soldering, the circuit module 30 can be corrected to a non-defective product when there is a soldering defect in the inspection process.

  (3) In the above embodiment, the circuit module 30 in which the circuit elements 50 a to 50 f are mounted on the substrate 35 is flux-washed with a cleaning liquid and then mounted on the package body 1. As a result, when each circuit element 50a to 50f is mounted on the concave bottom portion of the conventional package body 1, the problem that flux residue is likely to be generated at the concave bottom portion can be solved, and high cleaning properties can be secured. It is possible to suppress migration of circuit wiring on the substrate 35 due to the above. Moreover, it can also be suppressed that a flux residue adheres to the piezoelectric vibrating piece 20 and causes a malfunction. Therefore, it becomes possible to obtain the piezoelectric device 10 having high reliability.

(Second Embodiment)
In the first embodiment, the piezoelectric device 10 having a structure in which the circuit module 30 on which the plurality of circuit elements 50a to 50f are mounted is directly mounted on the package body 1 is described. However, the present invention is not limited to this. It is good also as a structure mounted in the package main body 1 by resin-sealing the junction part with the several circuit element and board | substrate mounted in the circuit module.

FIG. 3A is a front view for explaining the structure of a piezoelectric device on which a resin-sealed circuit module is mounted, and FIG. 3B is a cross-sectional view of the piezoelectric device shown in FIG. A sectional view and FIG. 4 are flowcharts of the manufacturing process of the piezoelectric device 60 of the second embodiment. Note that, in the configuration of the piezoelectric device 60 of the second embodiment, the same configuration as that of the first embodiment described above will be described using the same reference numerals, and the description of the same configuration will be omitted.
In FIG. 3A, the piezoelectric device 60 is mounted with the piezoelectric vibrating piece 20 and the resin-sealed circuit module 70 being electrically connected to the concave bottom portion of the package body 1. Is sealed by the package lid 2.

  In the resin-sealed circuit module 70, circuit elements 50a to 50f corresponding to a plurality of pairs of pattern electrodes 32a to 32l formed on the main pattern forming surface 31a of the substrate 35 are bonded by solder bonding, and sealed. Resin-sealed with a stop resin 100. External connection terminals 33a and 33b are formed on the back surface 31b of the substrate 35, and are electrically connected to the wiring pattern of the main pattern forming surface 31a by a through hole having conductivity (not shown). The resin-encapsulated circuit module 70 positions the mount electrodes 3a and 3b formed on the concave bottom portion of the package body 1 and the external connection terminals 33a and 33b corresponding to the mount electrodes 3a and 3b, respectively, and is joined by solder.

Next, a method for manufacturing the piezoelectric device 60 will be described with reference to the drawings.
In step S21, each circuit element 50a-50f is mounted on the substrate 35 by SMT to manufacture a circuit module.
In step S22, the circuit module is cleaned with a cleaning liquid made of an organic solvent or the like to remove flux, solder balls generated by solder reflow, and the like.

  In step S23, the circuit module is sandwiched between upper and lower resin-sealed molds in which cavities are formed, and resin-sealed by a transfer mold method in which the sealing resin 100 is injected into the cavities and filled, and the resin-sealed circuit module 70 is manufactured. The resin sealing method is not limited to the transfer molding method, and other resin sealing methods such as a potting method in which the sealing resin 100 is discharged and applied by a dispenser may be used.

  In step S24, the resin-sealed circuit module 70 is inspected. The inspection includes an appearance inspection for determining the appearance quality such as unfilling of the sealing resin, and an electrical characteristic inspection method for determining the quality of the electrical characteristics of the circuit module, and at least one of them is performed. When it is determined as defective in the inspection (No in step S25), it is classified as a defective product (step S34).

  If it is determined that the product is non-defective in the inspection of the resin-sealed circuit module 70 (Yes in Step S25), the process proceeds to Step S26, and the resin sealing corresponding to the mount electrodes 3a and 3b of the package body 1 respectively. The resin-sealed circuit module 70 is mounted by aligning and soldering the external connection terminals 33a and 33b of the mold circuit module 70. Next, cleaning is performed with a cleaning liquid made of an organic solvent or the like to remove flux and the like (step S27).

  In step S28, the mount electrodes 4a and 4b of the package body 1 and the corresponding connection electrodes of the piezoelectric vibrating reed 20 are positioned, joined by a conductive adhesive, and the piezoelectric vibrating reed 20 is mounted.

  In step S29, the piezoelectric vibrating piece 20 is washed with pure water or the like, and then the frequency of the piezoelectric vibrating piece 20 is adjusted (step S30). The package body 1 on which the piezoelectric vibrating piece 20 and the resin-sealed circuit module 70 are mounted is baked by placing it in a drying furnace at a predetermined temperature for a predetermined time (step S31).

  Subsequently, in step S <b> 32, the package lid body 2 is joined to the upper surface of the package body 1 via the seal ring 9 to obtain the piezoelectric device 60. Finally, an electrical property inspection of the piezoelectric device 60 is performed (step S33), and a series of manufacturing processes is completed.

  According to this configuration, the resin-sealed circuit module 70 includes the mounted circuit elements 50 a to 50 f and the joint portions between the circuit elements 50 a to 50 f and the substrate 35 sealed with the sealing resin 100. Yes. As a result, for example, conductive foreign matters such as solder balls and solder scraps generated when the circuit elements 50a to 50f are mounted on the substrate 35 by SMT are removed in the circuit module cleaning step (step S22 in FIG. 4). The conductive foreign matter adheres to the piezoelectric vibrating piece 20 or its connecting portion when it remains without being clogged, and has an adverse effect on the vibration characteristics of the piezoelectric vibrating piece 20 or an adverse effect such as an electrical short circuit. The risk of doing it can be avoided. In addition, the substrate 35, each of the circuit elements 50a to 50f, and the outgas such as the flux when mounted by the SMT are generated and the piezoelectric vibrating reed 20 adheres to avoid problems such as adversely affecting the vibration characteristics. It becomes possible to do. Therefore, it is possible to provide the piezoelectric device 60 having excellent vibration characteristics by the piezoelectric vibrating piece 20 and high reliability.

  The present invention is not limited to the above-described embodiments, and the following modifications can also be implemented.

(Modification 1) In the first and second embodiments, when the circuit module 30 or the resin-sealed circuit module 70 is connected to the mount electrodes 3a and 3b provided on the concave bottom portion of the package body 1, Although the method of joining with solder was shown, it is not limited to this. For example, another bonding method may be used such as bonding the circuit module 30 to the mount electrodes 3a and 3b of the package body 1a using a conductive adhesive.
According to this configuration, since no solder paste is used, it is not necessary to perform flux cleaning after mounting the circuit module 30 or the resin-sealed circuit module 70, and the manufacturing process can be reduced.

  (Modification 2) In the first and second embodiments, the circuit elements 50a to 50f are joined to the substrate 35 by SMT using solder. However, the present invention is not limited to this. Other bonding methods such as using a conductive adhesive or bonding using an electric bonding material such as ACF (Anisotropic Conductive Film) may be used.

(A) is a front view explaining the structure of one Embodiment of the piezoelectric device of this invention. (B) is the sectional view on the AA line of Fig.1 (a). The flowchart figure of the manufacturing process of one Embodiment of the piezoelectric device of this invention. (A) is a front view explaining the structure of one Embodiment of the piezoelectric device of this invention. (B) is the sectional view on the AA line of Fig.3 (a). The flowchart figure of the manufacturing process of one Embodiment of the piezoelectric device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Package main body, 2 ... Package cover body as a cover body, 3a, 3b ... Mount electrode which is an electrode provided in the concave bottom part of a package main body, 4a, 4b ... Mount electrode which is an electrode to which a piezoelectric vibrating piece is joined DESCRIPTION OF SYMBOLS 10,60 ... Piezoelectric device which is a piezoelectric device, 32a-32l ... Pattern electrode which is an electrode of a board | substrate, 35 ... Board | substrate, 50a-50f ... Circuit element as an electronic component, 100 ... Resin of the electronic component joined to the board | substrate Sealing resin used for sealing.

Claims (2)

A package body having a plurality of electrodes provided on the bottom plane of the recess, wherein a recess is formed;
A piezoelectric vibrating piece, a plurality of electronic components, and a lid for hermetically sealing the inside of the recess of the package body,
A piezoelectric device having a structure in which the piezoelectric vibrating piece and the electronic component are joined to a plurality of electrodes of the package body,
The electronic device is bonded to a substrate, and the substrate is bonded to any one of the plurality of electrodes. The piezoelectric device according to claim 1.
An electronic component bonded to the substrate is sealed with a resin.

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