JP2015226190A - Crystal oscillator - Google Patents

Abstract

A crystal oscillator having an increased degree of freedom in designing the position and area of an external connection terminal is provided.
A crystal oscillator 1 comprising a piezoelectric vibrator 2 containing a piezoelectric vibrating piece 5 that vibrates at a predetermined frequency and an IC chip 3 including an oscillation circuit, the piezoelectric vibrator connected to the IC chip 3 2 and the resin pattern 18 covering the outer periphery of the IC chip 3 and the electrode pattern. The external connection terminal 23 on the resin 18 is connected to the electrode pattern through the through electrode 22 provided on the resin 18. ing.
[Selection] Figure 1

Description

  The present invention relates to a crystal oscillator that provides a degree of freedom in design that does not depend on the dimensions of an IC chip, and that enables a reduction in size and height.

A crystal oscillator in which an IC chip including a crystal resonator and an oscillation circuit is stacked in the height direction of the container body is widely used as a clock for electronic equipment, for example. In the conventional structure, an electrical connection to an external connection terminal is made by using a through electrode or wire bonding provided so as to penetrate between both main surfaces of the IC chip. However, a through electrode is formed in the IC chip. There are problems in each configuration, such as an increase in cost due to an increase in man-hours and an adverse effect on a reduction in height due to the height required for wire bonding.
Patent Document 1 discloses a piezoelectric oscillator in which a semiconductor device including an oscillation circuit is joined to a crystal resonator by soldering, and the periphery of the semiconductor device is filled with resin.

JP 2009-165102 A

  However, in the piezoelectric oscillator described in Patent Document 1, an external connection terminal is formed on the circuit function surface of a semiconductor device, so-called IC chip, and a connection terminal connected to the piezoelectric vibrator is formed on the surface facing the circuit function surface. ing. The external connection terminal and the connection terminal are electrically connected by a through electrode formed through the silicon substrate of the IC chip. The position of the through electrode is also limited by the configuration of the integrated circuit in the IC chip, and further downsizing of the IC chip may occur, and there is a possibility that the area for forming the through electrode on the IC chip cannot be secured. In the formation, there were restrictions on the position and area.

  A crystal oscillator according to the present invention is a crystal oscillator including a crystal resonator containing a crystal resonator element that vibrates at a predetermined frequency, and an IC chip including at least an oscillation circuit, and the crystal resonator connected to the IC chip And a resin covering the outer periphery of the IC chip and the wiring pattern, and an external connection terminal on the resin and the wiring pattern are connected through a through electrode provided in the resin.

  The penetrating electrode was disposed at any position on the four sides of the crystal resonator, and a terminal connected through the penetrating electrode was used as a temperature compensation data writing terminal. Further, the diameter of the through electrode is 0.2 mm or more.

  An IC chip is flip-chip bonded to a wiring pattern.

  An IC chip including a step of preparing a vibrator substrate in which a plurality of crystal resonators containing crystal resonator pieces that vibrate at a predetermined frequency are arranged vertically and horizontally, and at least an oscillation circuit on a surface on which mounting terminals of the vibrator substrate are formed. Forming a wiring path for connecting between the pad for mounting the IC and the mounting terminal, mounting the IC chip on the vibrator substrate, applying a resin to cover the IC chip and the vibrator substrate, and resin Forming a through-hole, forming a through-electrode by filling the through-hole with a metal material, and forming an external connection terminal on the through-electrode.

  The present invention has been made in order to solve the above-described problems, and can provide a crystal oscillator in which the degree of freedom in designing the position and area of the external connection terminals is increased.

2A is a cross-sectional view of the crystal oscillator 1. FIG. FIG. 2B is a plan view of the crystal oscillator 1. FIG. 2A is a cross-sectional view of the crystal unit 2. FIG. 4B is a plan view of the quartz crystal vibrating piece 5. (A) is sectional drawing of the crystal oscillator 1 in which the wiring pattern 20 was formed. FIG. 2B is a plan view of the crystal oscillator 1 on which the wiring pattern 20 is formed. FIG. 2A is a cross-sectional view of a crystal oscillator 1 on which an IC chip 3 is mounted. FIG. 2B is a plan view of the crystal oscillator 1 on which the IC chip 3 is mounted. (A) is sectional drawing of the crystal oscillator 1 which apply | coated resin 18. FIG. FIG. 2B is a plan view of the crystal oscillator 1 to which a resin 18 is applied. (A) is sectional drawing of the crystal oscillator 1 in which the penetration electrode 22 was formed. FIG. 2B is a plan view of the crystal oscillator 1 in which the through electrode 22 is formed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the scope of the present invention is not limited to these forms unless otherwise specified in the following description.

<Configuration of crystal oscillator 1>
The configuration of the crystal oscillator 1 will be described in detail with reference to FIGS. 1 and 2. FIG. 1A is a cross-sectional view of the crystal oscillator 1. FIG. 2B is a plan view of the crystal oscillator 1. The crystal oscillator 1 mainly includes a crystal resonator 2 and an IC chip 3. The crystal resonator 2 is formed by laminating a lid 4, a crystal resonator element 5 and a base 6. The quartz crystal vibrating piece 5, the lid 4 and the base 6 are bonded via a bonding material 7 such as polyimide or low melting point glass.

  FIG. 2A is a cross-sectional view of the crystal resonator 2. FIG. 4B is a plan view of the quartz crystal vibrating piece 5. The crystal vibrating piece 5 includes an excitation unit 8 and a frame unit 9. A through hole 10 is formed between the excitation part 8 and the frame part 9 so as to surround the excitation part 8. Providing this through hole 10 prevents the vibration of the excitation portion 8 from being transmitted to the frame portion, thereby improving the vibration characteristics. The excitation unit 8 and the frame unit 9 are connected by a connecting unit 11.

  The quartz crystal vibrating piece 5 is a rectangular thin plate made of quartz, and is made of, for example, AT-cut quartz. Excitation electrodes 12 are formed on the front and back sides of the excitation unit 8 located substantially at the center of the crystal vibrating piece 5. By applying an alternating voltage to the excitation electrode 12, a thickness-shear vibration is generated in an AT-cut quartz crystal and vibrates at a predetermined frequency. The excitation electrode 12 is electrically connected to the extraction electrode 13 formed on the connecting portion 11 and the frame portion 9. Castellations 14 are formed at the four corners of the frame portion 9, and side electrodes 15 are formed on the surface of the castellations 14.

  The base 6 is a rectangular plate made of a brittle material such as glass or quartz, and castellations 14 are formed at the four corners like the crystal vibrating piece 5. Side electrodes 15 are formed on the surface of the castellation 14. The base 6 is formed with a recess so that the excitation portion 8 of the crystal vibrating piece 5 does not come into contact with the base 6, but the thickness of the excitation portion 8 of the crystal vibrating piece 5 is thinned so as to have a flat mesa structure. Even if the base 6 is not in contact, the concave portion need not be formed.

  A connection electrode 16 is formed on the surface of the base 6 on the side to be bonded to the crystal vibrating piece 5. On the other hand, a mounting terminal 17 is formed on the surface facing the surface to be bonded to the crystal vibrating piece 5. The connection electrode 16 is connected to the mounting terminal 17 through the side electrode 15 formed on the castellation 14.

  In the crystal oscillator 1 of the present invention, the resin 18 is coated on the mounting terminals 17 and is not a terminal used as a product when mounting on the substrate, but the crystal resonator 2 of the present invention is manufactured exclusively for the crystal oscillator. However, since it can be manufactured by combining a general-purpose crystal resonator, the mounting terminals described in the usual description are used.

  Further, the quartz crystal vibrating piece 5 here has a structure having a frame portion 9, but the quartz crystal vibrating piece 5 made of a normal rectangular plate is joined to the base 6 via a conductive adhesive, and the base 6 or the lid 4. Alternatively, a quartz resonator having a structure in which a cavity is formed and the quartz vibrating piece 5 is accommodated in the cavity may be used. In this case, a base 6 made of a multilayer ceramic and a lid 4 made of metal can be used.

  The lid 4 is a rectangular thin plate made of a brittle material such as glass or quartz. The castellations 14 may or may not be formed at the four corners according to the shape of the crystal vibrating piece 5 and the base 6. In addition, a concave portion is formed in the lid 4 similarly to the base 6, but the concave portion may not be formed when the excitation portion 8 of the crystal vibrating piece 5 does not contact.

  The crystal resonator element 2 is formed by bonding the crystal vibrating piece 5, the lid 4, and the base 6 using the bonding material 7. By connecting the electrode formed on the joint surface between the base 6 and the crystal vibrating piece 5, the mounting terminal 17 and the excitation electrode 12 are electrically connected.

  The structure of the IC chip 3 and its periphery will be described with reference to FIG. FIG. 3A is a cross-sectional view of the crystal oscillator 1 on which the wiring pattern 20 is formed. FIG. 2B is a plan view of the crystal oscillator 1 on which the wiring pattern 20 is formed. The IC chip 3 shown in FIG. 1 is a semiconductor element including at least an oscillation circuit, and further uses a temperature sensor circuit that senses the ambient temperature of the crystal oscillator 1 and an output of the temperature sensor circuit to generate a crystal resonator 2. The temperature compensation circuit for compensating the temperature characteristic and making the frequency constant even when the temperature changes is included.

  An IC mounting terminal 19 and a wiring pattern 20 are formed together with the mounting terminal 17 on the surface of the base 6 where the mounting terminal 17 is formed. The IC chip 3 is connected to the IC mounting terminal 19 of the base 6 by ultrasonic thermocompression (so-called flip chip bonding) using the bumps 21. A conductive path is formed directly on the crystal resonator 2 without using another housing or the like, and the IC chip 3 and the crystal vibrating piece 5 are connected. Therefore, the quartz crystal resonator element 5 and the IC chip 3 are thermally coupled to each other, and even if the ambient temperature changes, a temperature difference is hardly generated. For this reason, the starting characteristics can be improved.

  The manner in which the IC chip 3 is mounted on the crystal resonator 2 will be described with reference to FIG. FIG. 4A is a cross-sectional view of the crystal oscillator 1 on which the IC chip 3 is mounted. FIG. 2B is a plan view of the crystal oscillator 1 on which the IC chip 3 is mounted. The IC chip 3 has various IC terminals on the circuit function side. The IC terminal includes a pair of crystal IC terminals, a power supply terminal, an output terminal, a ground terminal, an automatic frequency control (AFC) terminal, and a pair of write IC terminals. The IC terminal is bonded to the IC mounting terminal 19 formed on the base 6 through the bump 21 using, for example, flip chip bonding.

  The pair of crystal IC terminals are connected to the crystal vibrating piece 5 via the wiring pattern 20 connected to the mounting terminal 17 of the base 6. A pair of crystal IC terminals, a power supply terminal, an output terminal, a ground terminal, and an automatic frequency control (AFC) terminal are drawn out to the four corners of the crystal resonator 2 through the wiring pattern 20, and through electrodes 22 formed in the resin 18 are connected. Via, it is electrically connected to the external connection terminal 23 formed on the surface of the resin 18. The pair of write IC terminals are led out to the center of two opposite sides through the wiring pattern 20 and led out to the surface of the resin 18 through the through electrodes 22 formed so as to straddle the sides.

  The resin covering the IC chip 3 will be described with reference to FIG. FIG. 5A is a cross-sectional view of the crystal oscillator 1 to which the resin 18 is applied. FIG. 2B is a plan view of the crystal oscillator 1 to which a resin 18 is applied. The outer periphery of the IC chip 3 and the surface on which the mounting terminals 17 of the base 6 are formed are covered with a resin 18 such as epoxy or polyimide. The thickness of the resin 18 is set to a thickness that completely covers the upper surface of the IC chip 3, for example. By completely covering the periphery of the IC chip 3 with the resin 18, the influence of the surrounding environment is prevented from being transmitted to the IC chip 3, and the frequency characteristics of the crystal oscillator 1 are stabilized.

  The through electrode 22 formed in the resin 18 will be described with reference to FIG. FIG. 6A is a cross-sectional view of the crystal oscillator 1 in which the through electrode 22 is formed. FIG. 2B is a plan view of the crystal oscillator 1 in which the through electrode 22 is formed. The resin 18 is provided with a through hole and filled with a metal paste such as tungsten or copper to form a through electrode 22. An external connection terminal 23 electrically connected to the through electrode 22 is formed on the surface of the resin 18.

  The thickness of the resin 18 may be matched with the position of the upper surface of the IC chip 3 or may be made lower than the position of the upper surface of the IC chip 3 by the thickness of the external connection terminal 23. By setting the height of the resin 18 in this way, the height of the crystal oscillator 1 can be reduced.

<Manufacturing method of crystal oscillator>
Next, a method for manufacturing a crystal oscillator will be described. Three substrates are prepared in which a plurality of lids 4, crystal vibrating pieces 5, and bases 6 are arranged. In the drawing, only one crystal oscillator 1 is shown for simplification, but actually, the lid 4, the crystal vibrating piece 5, and the base 6 are formed on the wafer in a state where the crystal oscillators 1 are arranged vertically and horizontally. .

  A lid substrate in which a plurality of lids 4 are arranged vertically and horizontally is prepared. For the lid substrate, for example, circular, elliptical, or rectangular through-holes that extend evenly across the four lids 4 adjacent to each other vertically and horizontally are provided at the four corners of each of the lids 4 that are divided into a plurality of parts by wet etching. This will later become a ¼ circle, ¼ ellipse or rectangular castellation 14. In addition, a recess is formed so that the excitation unit 8 does not come into contact with the center of each lid 4. This is formed using, for example, wet etching.

  A vibrating piece substrate having a plurality of quartz vibrating pieces 5 arranged vertically and horizontally is prepared. A through hole 10 that surrounds the excitation unit 8 is formed on the vibration piece substrate using, for example, wet etching, and the excitation unit 8 and the frame unit 9 are separated. Next, the excitation electrode 12 and the extraction electrode 13 made of chrome in the lower layer and gold in the upper layer are formed on the vibrating reed substrate using photolithography.

  For example, a circular, elliptical, or rectangular shape that evenly spans four crystal vibrating pieces 5 that are vertically and horizontally adjacent to the four corners of each crystal vibrating piece 5 that is divided into a plurality of pieces using wet etching, for example. A through hole is provided. This will later become a ¼ circle, ¼ ellipse or rectangular castellation 14. Side electrodes 15 are formed on the surface of the castellation 14.

  The excitation electrode 12 and the extraction electrode 13 on the side joined to the lid 4 of the crystal vibrating piece 5 are extracted to the base 6 side via the side surface electrode 15 formed on the castellation 14.

  A base substrate having a plurality of bases 6 arranged vertically and horizontally is prepared. As with the lid substrate, circular, elliptical, or rectangular through-holes that equally span four bases 6 that are vertically and horizontally adjacent to each other are provided at four corners of each base 6 to form a castellation 14. At the same time, a recess is formed in the center of each base 6 so that the excitation unit 8 does not contact. The recess is formed using, for example, wet etching. Next, the side electrode 15 located on the surface of the castellation 14 and the mounting terminal 17 formed on the surface of the base 6 opposite to the surface bonded to the crystal vibrating piece 5 are formed on the base substrate. Usually, the side electrode 15 and the mounting terminal 17 are formed in a two-layer structure using chromium as a lower layer and gold as an upper layer by using photolithography.

  Next, the three substrates are bonded in a laminated state so that the resonator element substrate is sandwiched between the lid substrate and the base substrate. For this bonding, a bonding material 7 such as low melting point glass or polyimide can be used, or direct bonding such as anodic bonding or surface activated bonding can be used. A space including the excitation unit 8 of the crystal vibrating piece 5 is an airtight space filled with an inert gas such as vacuum or nitrogen. As a result, a crystal resonator in a state where adjacent crystal resonators are connected to each other is completed.

  Subsequently, the characteristic inspection of each crystal resonator 2 is performed before the IC chip 3 is mounted on the base substrate. The frequency of the crystal resonator is measured by bringing the probe of the temperature device into contact with the mounting terminal 17, applying a predetermined alternating voltage to oscillate, and reading the oscillation signal generated at that time.

  As shown in FIG. 3B, a metal film made of Au, Cu, or the like is formed on the base substrate by sputtering, vapor deposition, or the like, and IC mounting terminals 19 are formed. The IC mounting terminal 19 may be performed at the same time as the mounting terminal 17 is formed on the base substrate. Next, as shown in FIGS. 4A and 4B, the IC chip 3 is mounted on the IC mounting terminal 19. Here, flip chip bonding using Au balls or solder balls, a conductive adhesive, or an anisotropic conductive sheet may be used.

  Next, as shown in FIGS. 5A and 5B, the resin 18 is filled so as to cover the IC chip 3, for example, using a transfer mold, and filled to a thickness at least covering the IC chip 3. After an epoxy resin or a polyimide resin is applied by spin coating or spraying, the outer periphery on which the IC chip 3 is mounted is resin-molded.

  The configuration of the through electrode 22 will be described with reference to FIGS. 6 (a) and 6 (b). A through hole is formed in a part of the resin molded to form the through electrode 22 using photolithography or laser processing. A through hole penetrating in the vertical direction of the resin 18 is formed at a position corresponding to the mounting terminal 17. The through-hole 22 is formed by filling the through-hole formed in the resin 18 with a metal such as tungsten, copper, or gold by sputtering or plating. Thereafter, as shown in FIGS. 1A and 1B, external connection terminals 23 that are electrically connected to the through electrodes 22 are formed on the surface of the resin 18 by plating or sputtering.

Subsequently, cutting is performed using, for example, dicing at the position of each product unit. In this way, a large number of crystal oscillators 1 can be formed simultaneously.
After the division, temperature characteristic measurement is performed to obtain temperature characteristic data, and a temperature characteristic parameter for the temperature compensation circuit is calculated based on the temperature characteristic data. The temperature compensation data is written by bringing the probe for writing the temperature characteristic parameter thus calculated into contact with the external connection terminal 23 for each temperature compensation type crystal oscillator. In this process, a temperature compensated crystal oscillator is completed that keeps the frequency within a specified range even if the temperature changes.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  Moreover, although the material which comprises a vibration piece was described as quartz, you may use a different piezoelectric material. For example, lithium tantalate or lithium niobate can be used.

  DESCRIPTION OF SYMBOLS 1 ... Crystal oscillator, 2 ... Crystal oscillator, 3 ... IC chip, 4 ... Lid, 5 ... Crystal vibrating piece, 6 ... Base, 7 ... Bonding material, 8 ... Excitation part, 9 ... Frame part, 10 ... Through-hole, DESCRIPTION OF SYMBOLS 11 ... Connection part, 12 ... Excitation electrode, 13 ... Extraction electrode, 14 ... Castellation, 15 ... Side electrode, 16 ... Connection electrode, 17 ... Mounting terminal, 18 ... Resin, 19 ... IC mounting terminal, 20 ... Wiring pattern, 21 ... Bump, 22 ... Penetration electrode, 23 ... External connection terminal

Claims (5)

  A crystal oscillator comprising a crystal resonator containing a crystal resonator element that vibrates at a predetermined frequency, and an IC chip including at least an oscillation circuit, the wiring provided on the bottom surface of the crystal resonator connected to the IC chip A crystal oscillator comprising a pattern and a resin covering the outer periphery of the IC chip and the wiring pattern, wherein an external connection terminal on the resin and the wiring pattern are connected through a through electrode provided in the resin.   The crystal oscillator according to claim 1, wherein the through electrode is arranged at any position on four sides of the crystal resonator, and a terminal connected through the through electrode is used as a temperature compensation data writing terminal.   The crystal oscillator according to claim 2, wherein a diameter of the through electrode is 0.2 mm or more.   The crystal oscillator according to claim 1, wherein the IC chip is flip-chip bonded to the wiring pattern.   In a method for manufacturing a crystal oscillator, a step of preparing a resonator substrate in which a plurality of crystal resonators containing crystal resonator pieces that vibrate at a predetermined frequency are arranged vertically and horizontally, and a surface on which mounting terminals of the resonator substrate are formed Forming a wiring path for connecting between the mounting terminal and a pad on which an IC chip including at least an oscillation circuit is mounted; mounting the IC chip on the vibrator substrate; and the IC chip and the vibration A step of applying a resin to cover the sub-substrate, a step of forming a through hole in the resin, a step of forming a through electrode by filling the through hole with a metal material, and an external connection terminal on the through electrode The manufacturing method of the crystal oscillator including the process of forming.