JP2012090203A - Piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage-controlled piezoelectric oscillator that is easily adjustable in frequency variation.SOLUTION: A voltage-controlled quartz oscillator 10 comprises: a quartz vibrating reed X; an IC chip 40 as a semiconductor circuit element including among others an oscillation circuit for oscillating the quartz vibrating reed X; and an inductance Lconnected in series with the quartz vibrating reed X. The inductance Luses an inductor circuit pattern disposed between layers of a package as a laminated circuit board housing the quartz vibrating reed Xand the IC chip 40; and bonding pads a-d drawn to a surface of the package via interlayer wiring and the like from a plurality of first lead terminals disposed between beginning and terminal ends of the inductor circuit pattern. Any one of the bonding pads b, c, d is connected to an electrode pad 45 of the IC chip 40 via a bonding wire 37, and a terminal end a of the inductance Lis connected to the quartz vibrating reed X.

Description

The present invention relates to a piezoelectric oscillator used as a frequency control device, and more particularly to a voltage-controlled piezoelectric oscillator.

Conventionally, surface-mount type piezoelectric devices configured by hermetically sealing a piezoelectric vibrating piece in a package have been widely used. Here, the piezoelectric vibrating piece uses a characteristic that a thin plate obtained by cutting a piezoelectric substrate such as quartz into a predetermined angle and thickness has a specific resonance frequency.
An AT-cut crystal vibrating piece that performs thickness-shear vibration using a thin plate obtained by cutting a piezoelectric substrate at a cut angle called an AT cut is used.
As a piezoelectric device using such a crystal vibrating piece, for example, a crystal vibrating piece and an electronic component such as a semiconductor circuit element including an oscillation circuit that oscillates the crystal vibrating piece are bonded and sealed in the same package. A crystal oscillator as a piezoelectric oscillator using a surface-mount crystal unit
It is widely used as a reference source such as frequency and time (for example, Patent Document 1).

In addition, the voltage controlled crystal oscillator described above has excellent characteristics such as high frequency stability and frequency control capable of correcting secular change. Widely used in various communication devices such as devices. FIG. 9 is a circuit diagram showing an example of a conventional voltage controlled crystal oscillator, where X ₁ is a crystal resonator, A ₁ is an amplifier, C _a and C _b are capacitors, D ₁ is a variable capacitance diode, and IN is a control. A voltage input terminal, R _d is a control voltage application resistor, and OUT is a frequency output terminal of the voltage controlled crystal oscillator.
A general equivalent circuit of the crystal unit X ₁ is represented as shown in FIG. In FIG. 7, L ₁
Is equivalent series inductance, C ₁ is equivalent series capacitance, R ₁ is equivalent series resistance, and C ₀ is parallel capacitance.
Load capacity of the circuit side containing the crystal resonator X ₁ viewed from amplifier A ₁ a (combined capacitance) and C _L, and the capacitance ratio and _{γ (C 0 / C 1)} , the resonance frequency f ₀ by the load capacitance C _L Change Δf / f
₀ is represented by the following well-known formula.
Δf / f ₀ = C ₀ / (2γ (C ₀ + C _L ))
That is, the resonant frequency of the voltage controlled crystal oscillator changes depending on the load capacitance in the oscillation loop.
The variable capacitance diode D ₁ is a Daodo the capacitance value changes according to the reverse voltage applied between the two terminals. Therefore, the oscillation frequency can be controlled by inserting the variable capacitance diode D ₁ into the oscillation loop and changing the applied voltage.

In addition, for example, Patent Document 2 discloses a voltage-controlled crystal oscillator having a configuration in which an inductance L is connected in series with a crystal resonator so that the frequency variable range can be further expanded and the frequency variable range can be adjusted. Yes. Inductance L inserted into the oscillation loop for such a purpose
Is generally referred to as an extension coil (or simply “coil”). This is a crystal resonator X ₁
When the inductance L is connected in series, the resonance frequency is lower than the frequency before the inductance L is inserted, but the anti-resonance frequency does not change, and therefore, it is based on the principle that the resonance / anti-resonance frequency interval is widened.
Further, in the voltage controlled crystal oscillator of Patent Document 2, as the inductance L inserted into the oscillation loop, a coarse adjustment coil A made of a chip inductor and a fine adjustment coil B made of a trimming coil are provided. It is connected in series with the crystal unit. The coil A is loaded so as to match the desired oscillation frequency and the vicinity of the frequency variable amount, and further, the coil B is trimmed, for example, by laser irradiation, and fine adjustment of the inductance value is performed. In addition, the frequency can be adjusted to the variable amount.

In recent years, with the spread of optical digital communication networks and mobile communication networks, the frequency stability is higher,
In addition, there is an increasing demand for a voltage controlled crystal oscillator having a wide variable frequency range. this is,
For example, when a voltage-controlled crystal oscillator is used as a local oscillator that constitutes a PLL (Phase Locked Loop) oscillator in network synchronization, the frequency shifts due to the deterioration of the crystal resonator element and other electronic components that constitute the oscillator over time. But if the frequency range is wide enough,
This is because it can be synchronized with the reference oscillation frequency supplied to the PLL oscillator.

JP 2002-374146 A JP 2008-177981 A

However, in the voltage-controlled crystal oscillator disclosed in Patent Document 2, it is necessary to mount a chip inductor on the circuit board of the crystal oscillator, and a laser irradiation apparatus for trimming a trimming coil for fine adjustment. In addition, there is a problem that an additional manufacturing process is required.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

Application Example 1 A piezoelectric oscillator according to this application example includes a piezoelectric vibrating piece, a semiconductor circuit element including an oscillation circuit for oscillating the piezoelectric vibrating piece, and the piezoelectric vibrating piece and the semiconductor circuit element are electrically connected to each other. And a circuit board including a circuit pattern to be connected, wherein the circuit pattern includes an inductor circuit pattern connected in series to the piezoelectric vibrating piece, and the inductor circuit is provided on a surface of the circuit board. A plurality of bonding pads drawn from a plurality of points between the beginning and end of the pattern are provided, and the semiconductor circuit element and the bonding pad are connected by wire bonding.

According to this configuration, by selecting a bonding pad to be wire-bonded from among a plurality of bonding pads, the inductor value is adjusted by changing the length of the inductor circuit pattern connected in series to the piezoelectric vibrating piece, and the piezoelectric oscillator The frequency variable amount can be adjusted. Therefore, it is not necessary to join an inductor element or increase the number of manufacturing processes and facilities such as laser irradiation, and a piezoelectric oscillator adjusted to a desired variable frequency can be provided relatively easily.

Application Example 2 In the piezoelectric oscillator according to the application example, the circuit board is a multilayer circuit board, the inductor circuit pattern is formed between the layers of the multilayer circuit board, and the inductor circuit pattern and the bonding pad pass through. They are connected by holes or via holes.

According to this configuration, the inductor circuit pattern is insulated from the surface of the circuit board, and the piezoelectric vibrating piece, the semiconductor circuit element, and the inductor circuit pattern can be vertically arranged in an insulated state. A high-performance piezoelectric oscillator can be provided.

Application Example 3 In the piezoelectric oscillator according to the application example described above, the inductor circuit pattern is formed between a plurality of layers of the multilayer circuit board.

In this configuration, an inductor circuit pattern formed between a plurality of layers is connected in series, an independent inductor circuit pattern is formed between each layer, and each is drawn out to a bonding pad provided on the surface of the substrate; ,including.
According to such a configuration, the length of the inductor circuit pattern and the degree of freedom of the shape are improved, so that it is possible to widen the adjustment range of the frequency variable range of the piezoelectric oscillator and perform highly accurate adjustment. .

Application Example 4 In the piezoelectric oscillator according to the application example, the inductor circuit pattern is formed between one layer of the multilayer circuit board.

According to this configuration, it is possible to provide a piezoelectric oscillator that is relatively easily adjusted to a desired variable frequency using a laminated circuit board manufactured by a simple manufacturing process.

(A) is a top view which illustrates typically one Embodiment of the quartz crystal vibrating piece as a piezoelectric vibrating piece concerning the piezoelectric oscillator of this invention seeing from an upper side, (b) is the AA line schematic of (a). Plan view. (A) is a top view which illustrates typically one Embodiment of the voltage control type crystal oscillator as a piezoelectric oscillator concerning this invention, (b) is the BB sectional drawing of (a). The schematic plan view of the 1st layer board | substrate of the package as a circuit board. The schematic plan view of the 2nd layer board | substrate of a package. The schematic plan view of a package. The circuit diagram explaining an example of the circuit structure of the voltage control type crystal oscillator as a piezoelectric oscillator. The circuit diagram explaining an example of the equivalent circuit of a crystal oscillator. The flowchart explaining an example of the manufacturing process of a voltage controlled crystal oscillator. The circuit diagram explaining an example of the voltage control type crystal oscillator as a conventional piezoelectric oscillator.

Hereinafter, a voltage controlled crystal oscillator as a piezoelectric oscillator will be described with reference to the drawings.

[Crystal resonator element]
First, the crystal resonator element 1 as a piezoelectric resonator element mounted on the voltage controlled crystal oscillator will be described. FIG. 1 schematically illustrates a crystal resonator element 1 included in a voltage-controlled crystal oscillator according to the present embodiment. FIG. 1A is a plan view seen from above, and FIG. 1B is a plan view of FIG. It is AA sectional view.
In FIG. 1, the quartz crystal resonator element 1 uses, for example, an AT-cut quartz substrate as a piezoelectric substrate obtained by shaping a quartz base material cut out from a quartz block at a cut angle called a so-called AT cut into a predetermined shape. ing. Further, the quartz crystal resonator element 1 of the present embodiment has a so-called mesa shape having first and second projecting portions 5A and 5B in which a part of both main surfaces of a rectangular flat plate-shaped quartz substrate protrudes to become a thick portion. Presented.

A first excitation electrode 15A, which is a drive electrode, is provided on the first protrusion 5A on one main surface side of the mesa-shaped quartz substrate. Further, a first external connection electrode 18 is provided near one end of the quartz substrate.
A is provided. The first excitation electrode 15A and the first external connection electrode 18A are electrically connected by a first interelectrode wiring 16A.
Similarly, a second excitation electrode 15B that is a counter electrode of the first excitation electrode 15A is provided on the second protrusion 5B on the other main surface of the quartz substrate, and the second excitation electrode 15B in the vicinity of one end side of the quartz substrate is provided. The first external connection electrode 18A and the second external connection electrode 18B provided in a region that does not overlap in plan view are electrically connected by the second inter-electrode wiring 16B.
In the mesa-shaped quartz substrate, the first and second excitation electrodes 15A and 15B provided with the first
And the thick part which consists of 2nd protrusion part 5A, 5B becomes a vibration part of the quartz-crystal vibrating piece 1. FIG. The first
In addition, the vicinity of one end side of the quartz crystal substrate on which the second external connection electrodes 18A and 18B are formed becomes a bonding portion (supporting portion) when the quartz crystal vibrating piece 1 is bonded to the package 20.

The first and second excitation electrodes 15A and 15B and the first and second external connection electrodes 18A and 18
B, electrodes and wirings such as the first and second inter-electrode wirings 16A and 16B are formed by, for example, vapor deposition or sputtering after etching the quartz substrate (quartz wafer) to form the outer shape of the mesa-type quartz vibrating piece 1. It can be formed by using nickel (Ni) or chromium (Cr) as a base layer, forming a metal film of, for example, gold (Au) thereon, and then patterning using photolithography.

[Voltage controlled crystal oscillator]
Next, a voltage controlled crystal oscillator using the crystal resonator element 1 will be described. FIG. 2 illustrates an embodiment of a voltage-controlled crystal oscillator using the crystal resonator element 1 described above.
(a) is a top view, (b) is the BB sectional drawing of (a). In FIG. 2A, for convenience of explaining the internal structure of the crystal resonator, the illustration of the lid 30 as a lid bonded to the upper portion of the crystal resonator is omitted, and the mounting position of the lid 30 is an imaginary line. It is indicated by (two-dot chain line). 3, 4, and 5 illustrate specific wiring examples of each substrate layer in the stacked structure of the package 20 as a circuit substrate used in the voltage controlled crystal oscillator. First
FIG. 4 is a schematic plan view of a second layer substrate, and FIG. 5 is a schematic plan view of a package in which layers from a first layer substrate to a sixth layer substrate are stacked.

As shown in FIG. 2, the voltage controlled crystal oscillator 10 includes a package 20 as a circuit board, a crystal vibrating piece 1, and an I as a semiconductor circuit element including a drive circuit for driving the crystal vibrating piece 1.
C chip 40. The voltage-controlled crystal oscillator 10 of the present embodiment is a so-called SMD (Surface Mount Device) type in which the crystal resonator element 1 and the IC chip 40 are bonded and sealed in a recess of the package 20 and can be mounted on the surface. It is a crystal oscillator. Such SMD
This type of voltage-controlled crystal oscillator 10 is advantageous in reducing the size and thickness. Further, an SMD type voltage controlled crystal oscillator 10 standardized as a surface mount component is, for example,
Cut or shape the external connection lead wire to match the shape of the connection terminal of the external board, like a crystal unit that seals the quartz crystal piece bonded to the board by covering it with a cylindrical cap. Therefore, it is easy to automate mounting on an external substrate, which is advantageous for simplification of the mounting process and cost reduction.

The package 20 includes a substantially rectangular flat plate-like first layer substrate 21 and second layer substrate 22 that are sequentially stacked.
And a third layer substrate 23, and a fourth layer substrate 24, a fifth layer substrate 25, and a sixth layer substrate 26 having a substantially rectangular frame shape sequentially stacked on the third layer substrate 23. A seal ring 29 having a substantially rectangular frame shape is disposed on the six-layer substrate 26. Fourth layer substrate 2 having a substantially rectangular frame shape
As the size of the opening of the fourth to sixth layer substrates 26 increases upward, the package 20 has the upper surface side of the third layer substrate 23 as a concave bottom portion, and the fourth layer substrate 24 to sixth layer. A recess having a step opened to the layer substrate 26 side is formed.

In such a concave portion of the package 20, a die pad 61 on which the IC chip 40 is placed is provided on the upper surface of the third layer substrate 23 which becomes the concave bottom portion of the concave portion. In addition, external mounting terminals 62 are provided on the lower surface of the first layer substrate 21 serving as the outer bottom surface of the package 20 for use in bonding with an external substrate.
Further, on the step formed so as to surround the die pad 61 in plan view by the fourth layer substrate 24, a bonding pad 57 and a bonding pad 56a connected corresponding to a plurality of electrode pads 45 of the IC chip 40 to be described later. To 56d (see also FIG. 5).
Further, on the step formed by the fifth layer substrate 25 on the fourth layer substrate 24, a plurality of resonator element connection terminals 65 to which the crystal resonator element 1 is bonded are provided.
Note that each of the vibration piece connection terminals 65, the bonding pads 57, the bonding pads 56a to 56d, or the external mounting terminals 62 is connected to the first layer substrate 21 to the sixth layer.
Corresponding terminals are connected to each other by in-layer wiring such as routing wiring or through-holes (not shown) formed on the layer substrate 26 to form circuit wiring.

Here, in the voltage controlled crystal oscillator 10 of the present embodiment, an inductor circuit pattern provided on the package 20 as a circuit board, which is a major feature, will be described in detail with reference to the drawings. As shown in FIG. 2B and FIG.
Is provided on the upper surface of the first layer substrate 21, which is an interlayer between the first layer substrate 21 and the second layer substrate 22 of the multilayer package 20. The inductor circuit pattern 50 is an inductance inserted into the oscillation loop of the oscillation circuit of the voltage controlled crystal oscillator 10 formed in the package 20 as a circuit board, and is generally called an extension coil or simply a coil. The inductor circuit pattern 50 according to the present embodiment is formed as a coil having a shape in which a plurality of elongated wirings 51 are folded back from one end to the other end on the upper surface of the first layer substrate 21. The shape of the inductor circuit pattern 50 is not limited to this, and may be any shape as long as the length from the start end to the end of the inductor circuit pattern formed by the wiring 51 is as long as possible. For example, the shape may be a spiral shape.

Between the start end and the end of the inductor circuit pattern 50, there are a plurality of first lead terminals 51a to 51d provided at predetermined intervals. Inductor circuit pattern 5 of this embodiment
0 includes four first lead terminals 51a, 51b, 51c, and 51d.
The first lead terminals 51a, 51b, 51c, 51d are connected to the intra-layer wirings 52a, 52b, 52c, 52 such as through holes or via holes formed in the layer of the second layer substrate 22 shown in FIG.
d is drawn to the upper surface of the second layer substrate 22 (the surface laminated with the third layer substrate 23).
The intra-layer wirings 52a, 52b, 52c, and 52d led out to the upper surface of the second layer substrate 22 are placed at predetermined positions on the upper surface of the second layer substrate 22 through the inter-terminal wirings 53a, 53b, 53c, and 53d, respectively. It is connected to the provided second lead terminals 54a, 54b, 54c, 54d.
The predetermined position on the upper surface of the second layer substrate 22 where the second lead terminals 54a, 54b, 54c, 54d are provided is the upper surface of the fourth layer substrate 24 of the package 20 shown in FIG. It is a position that overlaps the bonding pads 56a, 56b, 56c, 56d provided on the surface to be laminated in a plan view.

In FIG. 5, bonding pads 56 a to 56 d provided on the upper surface of the fourth layer substrate 24.
Among them, the bonding pad 56d provided at a position overlapping the second lead terminal 54d provided on the second layer substrate 22 in a plan view is formed by connecting the third layer substrate 23 and the second pad 23d as shown in FIG. The second lead terminal 54d is electrically connected by an intra-layer wiring 55d such as a through hole or a via hole formed through the layer of the four-layer substrate 24. Similarly, the bonding pads 56a, 56b, and 56c are overlapped in a plan view on the second layer substrate 22 by the intra-layer wiring formed through the layers of the third layer substrate 23 and the fourth layer substrate 24. Each of the second lead terminals 54a, 54b, 54c provided at the position is electrically connected.
Further, in FIG. 2B, as described above, the second lead terminal 54d provided on the second layer substrate 22 which is electrically connected to the bonding pad 56d provided on the fourth layer substrate 24.
Is electrically connected to the first lead terminal 51d of the inductor circuit pattern 50 provided on the upper surface of the first layer substrate 21 through the inter-terminal wiring 53d and the intra-layer wiring 52d. That is, the first
A plurality of first lead terminals 51a-5 of the inductor circuit pattern 50 provided on the layer substrate 21.
Of 1 d, the first lead terminal 51 d is drawn to the bonding pad 56 d provided on the fourth layer substrate 24. Similarly, each of the other first lead terminals 51a, 51b, 51c of the inductor circuit pattern 50 on the first layer substrate 21 shown in FIG. 3 is a layer provided on the second layer substrate 22 shown in FIG. Internal wiring 52a, 52b, 52c, inter-terminal wiring 53a, 53b
53c, second lead terminals 54a, 54b, 54c, and third layer substrate 23 and fourth layer substrate 2
4 are drawn out to bonding pads 56a, 56b, and 56c provided on the upper surface of the fourth layer substrate 24 shown in FIG.

In the voltage controlled crystal oscillator 10 as the piezoelectric oscillator of the present invention, the inductor circuit pattern 50 provided on the upper surface of the first layer substrate 21 of the package 20 shown in FIG. The inductance L connected in series to the quartz crystal vibrating piece 1 as the piezoelectric vibrating piece is formed. In the present embodiment, the inductor circuit pattern 50
Of the plurality of first lead terminals 51 a to 51 d, the first lead terminal 51 a is the terminal of the inductor circuit pattern 50, and the lead wiring drawn from the first lead terminal 51 a is connected to the crystal vibrating piece 1. Therefore, in FIG. 2A and FIG. 5, the inductor circuit pattern 5
For the convenience of explaining the purpose of drawing out each of the first lead terminals 51a to 51d of 0 to the bonding pad on the upper surface of the fourth layer substrate 24, the bonding pad 5 drawn from the first lead terminal 51a.
6a is illustrated, but the bonding pad 56a is not used for connection by wire bonding with the IC chip 40, so the bonding pad 56a is not provided.
It is good also as a structure connected to the crystal vibrating piece 1 by the lead wiring formed in the package 20. FIG.

As described above, the first layer substrate 21 to the sixth layer substrate 26 of the package 20 described above are made of a ceramic insulating material or the like. In addition, each electrode, terminal, and inductor circuit pattern 50 provided in the package 20 or a wiring pattern or an in-layer wiring pattern for electrically connecting them is generally made of tungsten (W), molybdenum (Mo), or the like. Metal wiring material is screen printed on ceramic insulating material and fired. On top of that, nickel (Ni), gold (Au)
It is formed by plating.

2A and 2B, an IC chip 40 as a semiconductor circuit element including a drive circuit for driving and vibrating the crystal resonator element 1 is formed on a die pad 61 provided in a concave bottom portion of a recess of the package 20. For example, it is bonded and fixed by a brazing material or an adhesive (not shown). Further, the IC chip 40 and the package 20 are electrically connected using a wire bonding method. That is, a plurality of electrode pads 45 provided on the IC chip 40,
Bonding wires 37 are connected to corresponding bonding pads of the package 20. Here, among the bonding pads 56a to 56d of the package 20 and the bonding pads 57 provided in correspondence with the plurality of electrode pads 45 of the IC chip 40, the plurality of first extraction terminals of the inductor circuit pattern 50 described above. The bonding pads 56a to 56d drawn from 51a to 51d are used for adjusting the frequency variable amount, and only one of them is connected to the IC chip 40 (details will be described later). In the present embodiment, among the bonding pads 56 a to 56 d for adjusting the frequency variable amount, the bonding pad 56 d and the electrode pad 45 of the IC chip 40 are connected by the bonding wire 37.

The crystal resonator element 1 includes external connection electrodes 18A and 18B provided in the vicinity of one end serving as a holding portion of the crystal resonator element 1, and a corresponding resonator element connection terminal 65 provided on the fifth layer substrate 25 of the package 20. Are joined together by a joining member such as a conductive adhesive 39. Thereby, the crystal resonator element 1 is connected to the external connection electrode 1 joined to the package 20.
The holding part provided with the external connection electrodes 18A and 18B is used as a fixed end in a state where the opposite side of the 8A and 18B sides is a free end and a gap is provided so as not to contact the lower fourth layer substrate 24 and the IC chip 40. Cantilevered.
The conductive adhesive 39 used as the joining member is generally made of a resin such as polyimide, silicon, or epoxy, silver (Ag) filament, or nickel (Ni).
The one mixed with powder is used. Further, the bonding member for bonding the crystal vibrating piece 1 is not limited to the conductive adhesive 39, and other bonding members such as solder may be used.

On the sixth layer substrate 26 of the package 20 to which the IC chip 40 and the crystal vibrating piece 1 are bonded, a lid 30 as a lid is bonded. Specifically, for example, a metal lid 30 such as 42 alloy (an alloy containing 42% nickel in iron) or Kovar (an alloy of iron, nickel and cobalt) is an iron-nickel (Fe-Ni) alloy. Etc. are seam-welded through a seal ring 29 formed by punching a frame shape. In addition to the above-mentioned metal, ceramics, glass, or the like can be used for the lid 30. For example, when the glass lid 30 is used, a low-melting glass is used as a bonding member.
A joining member is appropriately selected according to the material of 0, and the package 20 and the lid 30 can be joined.

A cavity formed by the package 20 and the lid 30 becomes a space for the quartz crystal resonator element 1 to operate. This cavity is the voltage controlled crystal oscillator 10 of this embodiment.
Can be sealed and sealed in a reduced pressure space or an inert gas atmosphere. For example, in a case where the inside of the cavity is hermetically sealed with a reduced pressure space, the solid sealing material is placed in a sealing hole (not shown) of the package 20 and placed in a vacuum chamber, and the pressure is reduced to a predetermined degree of vacuum. After the gas exiting from the inside of the voltage-controlled crystal oscillator 10 is discharged from the sealing hole, the solid sealing material is melted and then solidified to close the sealing hole and seal it. be able to. Thereby, the crystal vibrating piece 1 and the IC chip 40 bonded in the recess of the package 20 can be hermetically sealed.
In addition, as a material of the sealing material, a material having a melting point higher than a reflow temperature when the completed voltage controlled crystal oscillator 10 is mounted on an external mounting substrate is desirable. For example, gold and tin (Sn) Or an alloy of gold and germanium (Ge) can be used.

Next, the circuit configuration of the voltage controlled crystal oscillator 10 will be described with reference to the drawings.
An example of the circuit configuration of the voltage controlled crystal oscillator 10 of the present embodiment can be described with reference to the circuit diagram of FIG. 6 and FIG. 7 referred to in the description of the background art. That is, as shown in the circuit diagram of FIG. 6, the voltage controlled crystal oscillator 10 includes a variable capacitor such as a control voltage application resistor R _d , a varicap diode, or the like between a control voltage input terminal represented by Vc and a frequency output unit. Diodes D ₁ and D ₂ , crystal resonator X ₁ (crystal resonator element 1), capacitors C _a and C _b , amplifier A ₁ , and
It has an inductance, a so-called coil (extension coil) L ₁ . Here, the variable capacitance diode D ₁ is a Daodo which changes its capacitance value according to the reverse voltage applied. Therefore, the oscillation frequency can be controlled by inserting the variable capacitance diode D ₁ into the oscillation loop and changing the applied voltage. At this time, the greater the load capacitance value of the circuit, the greater the frequency variable sensitivity.

Here, a general equivalent circuit of the crystal unit X ₁ is represented as shown in FIG. 7, in which L ₁ is an equivalent series inductance, C ₁ is an equivalent series capacitance, R ₁ is an equivalent series resistance, and C ₀ is Parallel capacity. Load capacity of the circuit side containing the crystal resonator X ₁ viewed from amplifier A ₁ a (combined capacitance) and C _L, and the capacitance ratio and _{γ (C 0 / C 1)} , the resonance frequency f ₀ by the load capacitance C _L The change amount Δf / f ₀ is expressed by the following well-known expression.
Δf / f ₀ = C ₀ / (2γ (C ₀ + C _L ))
Accordingly, as shown in FIG. 6, when connected to a crystal resonator X ₁ the inductance L ₁ in series, an inductance L load capacitance C of ₁ when not inserted, the inductance L ₁ load capacity was measured with the C _L, the oscillation When the angular frequency is ω, the relationship is C _L = (1 / (1−ω ² LC)), and the frequency variable sensitivity can be increased by inserting the inductance L ₁ .

In the circuit of the voltage controlled crystal oscillator 10 of this embodiment shown in FIG.
₁ denotes the inductor circuit pattern 50 described with reference to FIGS. 2 to 5 and a plurality of first lead terminals 51 a to 5 provided between the start end and the end of the inductor circuit pattern 50.
Bonding pads 56a to 56d drawn from 1d are used. That is, d, c, b, and a between the starting end (d side) and the terminating end (a side) of the inductance L _{1 in} FIG. 6 correspond to the bonding pads 56d, 56c, 56b, and 56a, respectively. Of the bonding pads 56a to 56d (a to d in the figure), the bonding pads 56b, 56c, and 56d.
Is connected to the electrode pad 45 for connection to the crystal resonator X ₁ of the IC chip 40 by the bonding wire 37, and the terminal a of the inductance L ₁ (bonding pad 56 a) is connected to the crystal resonator X _1. The Thus, by changing the bonding pads 56b~56d to be connected to the IC chip 40 may change the length of the inductance L _1, it is possible to change the inductance value accordingly.

According to the voltage controlled crystal oscillator 10 of the present embodiment, a plurality of bondings led out from each of the plurality of first lead terminals 51a to 51d provided between the start end and the end of the inductor circuit pattern 50 provided in the package 20. By selecting a bonding pad for wire bonding among the pads 56b to 56d, the crystal resonator element 1 (crystal resonator X
_The inductor value is adjusted by changing the length of the inductor circuit pattern 50 connected in series in ₁ ), and the frequency variable amount of the voltage controlled crystal oscillator 10 as a piezoelectric oscillator can be adjusted. Therefore, there is no need to join the inductor element or trim the inductor by laser irradiation as in the conventional method of adjusting the frequency variable amount. Thus, it is possible to provide the voltage controlled crystal oscillator 10 adjusted to the frequency variable amount.

Further, in the voltage controlled crystal oscillator 10 of the present embodiment, a first layer substrate 21 and a second layer substrate are used by using a package 20 as a laminated circuit substrate as a circuit substrate to which the crystal resonator element 1 and the IC chip 40 are bonded. Inductor circuit pattern 50 is formed between layers 22 and bonding pads 56a-5 on the surface of package 20 using in-layer wiring such as through holes and via holes.
It was set as the structure pulled out to 6d.
With this configuration, the inductor circuit pattern 50 is insulated from the surface of the package 20,
Since the quartz crystal resonator element 1 and the IC chip 40 and the inductor circuit pattern 50 can be vertically arranged in an insulated state, a small and highly reliable voltage-controlled crystal oscillator 10 can be provided.

[Method for manufacturing voltage-controlled crystal oscillator]
Next, a method for manufacturing the voltage controlled crystal oscillator will be described with reference to the drawings.
FIG. 8 is a flowchart for explaining an example of a manufacturing method of the voltage controlled crystal oscillator 10 as a piezoelectric oscillator.
In FIG. 8, in the manufacturing process of the voltage controlled crystal oscillator 10, first, the package 20 shown in FIG. 2 is prepared. As shown in step S1, an IC is attached to the die pad 61 provided in the concave bottom portion of the concave portion of the package 20. The chip 40 is die-bonded. Specifically, an appropriate amount of die attach agent (not shown) is applied on the die pad 61, and then the IC chip 40 is aligned and mounted. Next, as shown in step S2, a drying step for drying the die attach material that solidifies the die attach agent by heating at a predetermined temperature and time,
The IC chip 40 is bonded and fixed on the die pad 61.

Next, as shown in step S3, the IC chip 40 and the package 20 are connected by the wire bonding method, and at the same time, the frequency variable sensitivity is adjusted.
The normal connection between the IC chip 40 and the package 20 is shown in FIG.
A plurality of bonding pads 57 arranged on the right side in the drawing on the fourth layer substrate 24 of 0 and the corresponding electrode pads 45 of the IC chip 40 are connected by bonding wires 37.
Further, the frequency variable sensitivity is adjusted by a plurality of bonding pads drawn out from each of the plurality of first lead terminals 51a to 51d provided between the start end and the end of the inductor circuit pattern 50 provided in the package 20 shown in FIG. It carries out by selecting the bonding pad which wire-bonds among 56a-56d. Thereby, the inductor value can be adjusted by changing the length of the inductor circuit pattern 50 connected in series to the crystal resonator element 1, and the frequency variable amount of the voltage controlled crystal oscillator 10 as the piezoelectric oscillator can be adjusted.

Next, as shown in step S4, the crystal vibrating piece 1 as a piezoelectric vibrating piece is packaged in a package 20.
Mount in the recess. Specifically, the external connection electrodes 18A and 18B provided in the vicinity of one end which is a holding portion of the crystal vibrating piece 1 and the corresponding vibrating piece connection terminal 65 provided on the fifth layer substrate 25 of the package 20 are positioned. In a combined state, the external connection electrodes 18A and 18B and the corresponding vibration piece connection terminal 65 are brought into contact with each other, and a bonding member of an amount necessary for obtaining the bonding strength of the crystal vibration piece 1; For example, a conductive adhesive 39 is applied to the package 2
The quartz crystal vibrating piece 1 is temporarily fixed to zero. In addition, after applying an appropriate amount of the conductive adhesive 39 on the vibration piece connection terminal 65 using a dispenser or the like as the order of this step, the crystal vibrating piece 1 is applied using the viscosity of the conductive adhesive 39. You may make it align and temporarily fix.

Next, as shown in step S5, the conductive adhesive 39 is heated at a predetermined temperature and time.
The quartz crystal vibrating piece 1 is bonded and fixed in two drying steps for solidifying. If the conductive adhesive 39 is of an ultraviolet curable type, the conductive adhesive 39 is solidified by irradiating the conductive adhesive 39 with ultraviolet rays having a predetermined intensity for a predetermined time, thereby adhering the crystal vibrating piece 1.・ Can be fixed.

Next, as shown in step S6, the frequency of the crystal vibrating piece 1 bonded to the package 20 together with the IC chip 40 is finely adjusted. The frequency adjustment is performed by removing a part of the electrode of the crystal vibrating piece 1 by laser trimming to reduce the mass, by adding mass to the crystal vibrating piece 1 such as vapor deposition or sputtering, or an IC chip. This can be done by a method of rewriting 40 data.

Next, as shown in step S <b> 7, a lid 30 as a lid is bonded onto the package 20, thereby sealing the package 20 in which the crystal vibrating piece 1 and the IC chip 40 are accommodated. In this embodiment, the lid 30 as a metal lid is joined by seam welding via a seal ring 29 made of, for example, an iron-nickel alloy. At this time, if necessary, the cavity formed by the package 20 and the lid 30 is a reduced pressure space,
Alternatively, it can be sealed and sealed in an inert gas atmosphere. For example, in a case where the inside of the cavity is hermetically sealed with a reduced pressure space, the solid sealing material is placed in a sealing hole (not shown) of the package 20 and placed in a vacuum chamber, and the pressure is reduced to a predetermined degree of vacuum. Then, after the gas exiting from the inside of the voltage controlled crystal oscillator 10 is discharged from the sealing hole, the solid sealing material is melted and then solidified to close and seal the sealing hole. Thereby, the crystal vibrating piece 1 and the IC chip 40 bonded in the recess of the package 20 can be hermetically sealed.
As another method for joining the lid 30, the lid 30 is joined to the package 20 through a metal brazing material such as solder, or the lid 30 made of glass is used to form the lid 20 with a low melting point glass or the like. Can also be joined.

Next, as shown in step S8, baking is performed in which the voltage-controlled crystal oscillator 10 in a sealed state is put into an oven at a predetermined temperature for a predetermined time.
Then, as shown in step S9, a characteristic inspection such as an electric characteristic inspection or an appearance inspection is performed to remove non-standard defective products, and a series of manufacturing processes of the voltage controlled crystal oscillator 10 is completed.

The voltage controlled crystal oscillator 10 described in the above embodiment can also be implemented as the following modifications.

(Modification)
In the voltage controlled crystal oscillator 10 of the above embodiment, the package 20 as a laminated circuit board.
2, an inductor circuit pattern 50 is provided on the upper surface of the first layer substrate 21, that is, between one layer of the first layer substrate 21 and the second layer substrate 22, and is provided between the start end and the end of the inductor circuit pattern 50. The plurality of first lead terminals 51a to 51d are configured to be drawn out to bonding pads 56a to 56d provided on the surface of the package 20 by using in-layer wiring such as through holes and via holes. However, the present invention is not limited to this, and the inductor circuit pattern may be formed between a plurality of layers of a multilayer substrate such as a package.
Here, the configuration in which an inductor circuit pattern is formed between a plurality of layers of a multilayer substrate is a configuration in which inductor circuit patterns formed between a plurality of layers are connected in series, and an independent inductor circuit pattern is formed between each layer, Each of which is pulled out to a bonding pad provided on the surface of the substrate.
According to such a configuration, the length and shape of the inductor circuit pattern are improved, so that the adjustment range of the frequency variable range of a piezoelectric oscillator such as a voltage-controlled crystal oscillator can be widened, or highly accurate adjustment can be performed. It becomes possible to go.

The embodiment of the present invention made by the inventor has been specifically described above, but the present invention is not limited to the above-described embodiment, and various modifications are made without departing from the scope of the present invention. Is possible.

For example, in the above-described embodiment, the voltage-controlled crystal oscillator 10 as a piezoelectric oscillator using the crystal resonator element 1 using a crystal substrate as the piezoelectric resonator element has been described. In addition to quartz, aluminum nitride (AlN), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), lead zirconate titanate (PZT), lithium tetraborate (Li ₂₎
Aluminum oxide, tantalum pentoxide (Ta) on oxide substrate such as B ₄ O ₇ ) or glass substrate
_A piezoelectric vibrating piece made of another piezoelectric material formed by stacking thin film piezoelectric materials such as ₂ O ₅ ) can also be used.

Moreover, the shape of the specific form demonstrated by the said embodiment and modification, for example, the crystal vibrating piece 1 as a piezoelectric vibrating piece, the package 20 as a circuit board (laminated circuit board), etc. is not limited.
For example, a piezoelectric vibrating piece such as a quartz vibrating piece is not limited to using an AT-cut quartz base material as in the above embodiment, and may be formed using a quartz base material having another cut angle. Further, the shape of the crystal vibrating piece is not limited to the mesa shape like the crystal vibrating piece 1 of the above-described embodiment, but may be a plate shape, a so-called inverted mesa shape, and a tuning fork type vibrating piece. May be.
In addition, the package 20 is not limited to the one having the laminated structure described in the above embodiment, but may be one integrated by machining or the like, or a piezoelectric oscillator using a single-layer circuit board. It can also be configured. For example, when a piezoelectric oscillator is configured using a single-layer circuit board, a piezoelectric oscillator having a mode in which a piezoelectric vibrating piece or a semiconductor circuit element is sealed in a cavity is formed by using a cap-shaped lid. can do.
Similarly, the position and shape of each electrode, wiring, terminal, etc. are not limited to the above embodiment.

DESCRIPTION OF SYMBOLS 1 ... Crystal oscillation piece as a piezoelectric oscillation piece, 5A ... 1st protrusion, 5B ... 2nd protrusion, 10 ... Voltage control type crystal oscillator as a piezoelectric oscillator, 15A ... 1st excitation electrode, 15B ... 2nd excitation electrode 1
6A ... first interelectrode wiring, 16B ... second interelectrode wiring, 18A ... first external connection electrode, 18B ...
Second external connection electrode, 20 ... Package as a circuit board (laminated circuit board), 21 ... First layer substrate, 22 ... Second layer substrate, 23 ... Third layer substrate, 24 ... Fourth layer substrate, 25 ... First 5-layer board, 2
6 ... Sixth layer substrate, 29 ... Seal ring, 30 ... Lid, 37 ... Bonding wire, 3
DESCRIPTION OF SYMBOLS 9 ... Conductive adhesive agent 40 ... IC chip as a semiconductor circuit element, 45 ... Electrode pad, 50
... Inductor circuit pattern, 51 ... Wiring, 51a-51d ... First lead terminal, 52a-52
d, 55d ... intra-layer wiring, 53a-53d ... inter-terminal wiring, 54a-54d ... second lead terminal,
56a to 56d, 57 ... bonding pads, 61 ... die pads, 62 ... external mounting terminals,
65: Vibration piece connection terminal.

Claims (4)

A piezoelectric vibrating piece;
A semiconductor circuit element including an oscillation circuit for oscillating the piezoelectric vibrating piece;
A circuit board including a circuit pattern to which the piezoelectric vibrating piece and the semiconductor circuit element are electrically connected,
The circuit pattern includes an inductor circuit pattern connected in series to the piezoelectric vibrating piece,
On the surface of the circuit board, a plurality of bonding pads drawn out from a plurality of points between the start end and the end of the inductor circuit pattern are provided,
The piezoelectric oscillator, wherein the semiconductor circuit element and the bonding pad are connected by wire bonding. The piezoelectric oscillator according to claim 1,
The circuit board is a multilayer circuit board, the inductor circuit pattern is formed between layers of the multilayer circuit board, and the inductor circuit pattern and the bonding pad are connected by a through hole or a via hole. Oscillator. The piezoelectric oscillator according to claim 2,
The piezoelectric oscillator, wherein the inductor circuit pattern is formed between a plurality of layers of the multilayer circuit board. The piezoelectric oscillator according to claim 2,
The piezoelectric oscillator, wherein the inductor circuit pattern is formed between one layer of the multilayer circuit board.

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