JP2003032041A - Piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric oscillator excellent in mass-productivity and productivity at a low cost. SOLUTION: The piezoelectric oscillator is provided with a piezoelectric element 3, a 1st package 1 provided with an electrode 1A conductive to the piezoelectric element 3 at a bottom face, and a 2nd package 2 on a recessed part 21 of a bottom side of which electronic components 4 such as a semiconductor integrated circuit are contained and mounted and having electrodes 2A, 2B conducted to the electronic components 4 at the upper side and the bottom side respectively and made of a layered ceramic incorporating a capacitor, and the bottom electrode 1A of the 1st package 1 and the upper electrode 2A of the 2nd package are electrically connected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric oscillator having high reliability and excellent mass productivity.

[0002]

2. Description of the Related Art In recent years, due to the rapid development of mobile communication,
There is a demand for downsizing and cost reduction of the terminal, and naturally, also for the reference signal source, there is a demand for downsizing and cost reduction. Here, a specific example of a conventional piezoelectric oscillator will be described with reference to FIGS. 7 and 8.

The piezoelectric oscillator shown in FIG. 7 is mounted and mounted on one surface of a package (hereinafter referred to as a ceramic package) 101 made of ceramic and provided with necessary conductive wiring via electrodes 102. Element 103,
Semiconductor integrated circuit 1 mounted on the back surface of the ceramic package 101 opposite to the surface on which the piezoelectric element 103 is mounted
04 and so on.

The ceramic package 101 has recesses in the upper and lower parts. Of these, the recess 10 on the upper side
The piezoelectric element 103 is housed in 1A. The piezoelectric element 103 is fixed and held by the electrode 102, and the cap 105 is adhered to the piezoelectric element 103 with the sealing material 106, so that the piezoelectric element 103 is hermetically sealed.

A semiconductor integrated circuit 104 is housed in the recess 101B on the lower side of the ceramic package 101, and is electrically connected to the ceramic package 101 via a wire (not shown) by wire bonding 107. At the same time, the recess 101B is molded with the sealing resin 108 and sealed in an airtight state.

As the bypass capacitor, a chip capacitor is mounted on a mother board (not shown) of the terminal, or the chip capacitor is housed as an electronic component 109 in the recess 101B of the ceramic package 101.

Further, this piezoelectric oscillator shown in FIG. 8 is also shown in FIG.
The piezoelectric oscillator has a configuration similar to that of the piezoelectric oscillator shown in FIG.
A is provided, and the semiconductor integrated circuit 1 is provided in the recess 110A.
04 is housed and connected to a wire (not shown) by wire bonding 107. The recess 110A on the bottom surface of the ceramic package 110 is molded with the sealing resin 108 and is hermetically sealed.

On the other hand, in this piezoelectric oscillator, the piezoelectric element 10 is also used.
The electrode 3 is fixed and held by the electrode 102, and the cap 111 is adhered from above by a sealing material 106 to be hermetically sealed.

In the piezoelectric oscillators shown in FIGS. 7 and 8, the semiconductor integrated circuit 104 is shipped in a state in which the temperature compensation data is written, but a terminal for writing the temperature compensation data (not shown). No.) is not structured to be electrically connected to the mother board of the terminal.

[0010]

In the conventional piezoelectric oscillator, the semiconductor integrated circuit (IC) 104 is mounted, the piezoelectric element 103 is mounted, and the cap 105 or 11 is used.
Since the process of hermetically sealing by 1 is consistently performed, in other words, since these are integrated together, either the semiconductor integrated circuit (IC) 104 is mounted or the piezoelectric element 103 is mounted. If a product defect occurs due to, both will be discarded. Under such circumstances, there is a problem that the piezoelectric oscillator has a low yield and causes an increase in cost.

Further, as described above, since the bypass capacitor is mounted on the mother board of the terminal or accommodated in the recess of the package, the total area and volume increase,
Further, there is a problem that the device is far from the oscillation circuit and is unstable with respect to noise and the like.

Further, if there is an error in writing the adjustment value or an error in measuring the frequency when the frequency is adjusted, or if a frequency shift occurs due to environmental changes after shipment, the error may occur after mounting on the mother board of the terminal. When a problem is discovered, readjustment is impossible even if the cause is known, and this piezoelectric oscillator is treated as a defective product and discarded, so that there is a problem that the yield further deteriorates.

In view of the above circumstances, the present invention has an object of providing a piezoelectric oscillator having excellent mass productivity and productivity, high reliability and high quality at low cost.

[0014]

According to the present invention, first, there is provided a first package having a piezoelectric element built-in and an electrode electrically connected to the piezoelectric element on a bottom surface, and a semiconductor integrated circuit or the like in a recessed portion on the bottom surface. A second package made of laminated ceramics that houses the electronic component and is electrically connected to the electronic component on the top surface and the bottom surface, and has a built-in capacitor, the bottom electrode of the first package and the second package. It is characterized in that it is electrically connected to the upper electrode.

As a result, when a defective portion is generated in either the first package or the second package, replacing one of them eliminates the above-mentioned inconvenience, so that the total amount is reduced. The yield can be improved over the conventional one. Further, since the laminated ceramic is used as the second package and the MIM capacitor is built in, the bypass capacitor can be formed at a position extremely close to the oscillation circuit, and an oscillator that can obtain stable characteristics against noise and the like. Can be configured. Further, since it is not necessary to secure a large mounting space like a chip capacitor, it is possible to realize a small area and a low cost.

Secondly, according to the present invention, a piezoelectric element is built-in, and a first package having an electrode for conducting the piezoelectric element on the bottom surface and an electronic component such as a semiconductor integrated circuit on the bottom surface are housed. , Providing electrodes on the top surface and the bottom surface that are electrically connected to the electronic component, and forming connection conductive bumps on the electrodes on the bottom surface,
A second package made of laminated ceramics containing a capacitor is provided, and a bottom electrode of the first package and an upper electrode of the second package are electrically connected.

Thirdly, a semiconductor integrated circuit or the like provided for adjusting an oscillation circuit section composed of the piezoelectric element in the first package and the semiconductor integrated circuit in the second package. It is preferable that an electrode that is electrically connected to a terminal on the electronic component is provided on the bottom surface of the second package so that the electrode and the mother board of the terminal can be electrically connected.

Thus, by providing the electrode on the bottom surface of the second package with the terminal for adjusting the oscillation circuit, the first package can be operated under the environment in which the first package, the second package and the mother board are connected. It is possible to adjust the oscillation circuit section including the piezoelectric element in the package and the electronic component such as the semiconductor integrated circuit in the second package.

Therefore, at the time of adjustment, writing error of the adjustment value,
Even if a frequency shift due to a measurement error or environmental change is found in a later process, readjustment is possible and the first package and the second package are discarded as defective products. It is not necessary, and the yield can be improved as a piezoelectric oscillator.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. In addition,
In this embodiment, the same parts as those in the prior art are designated by the same reference numerals to avoid redundant description.

[First Embodiment] FIGS. 1 to 3 show a piezoelectric oscillator according to a first embodiment of the present invention. This piezoelectric oscillator is roughly composed of a first package 1 and a first package 1. , The second package 2 and the piezoelectric element 3 not shown.
And the electronic component 4, and the first package 1
And the second package 2 are electrically connected to each other.

The first package 1 includes the piezoelectric element 3 described above.
As a crystal oscillator, a lower electrode 1A electrically connected to the piezoelectric element 3 is provided on the lower surface of the crystal oscillator, and the lower electrode 1A is electrically connected to the second package 2. Further, the lower electrode 1A corresponds to the first package 1
In this case, it also functions as an electrode for identifying the frequency of the piezoelectric element 3, and it is possible to eliminate mistaking mistakes with the first package 1.

The second package 2 is made of a laminated ceramic and has a built-in MIM (Metal Insulator Metal) capacitor serving as a bypass capacitor together with necessary conductive wiring. Also, this second package 2
Is formed in a shape having a recess 21 in the central portion on the lower surface (bottom surface) side, and the recess 21 accommodates the electronic component 4 described above. The electronic component 4 includes a semiconductor integrated circuit that forms an oscillation circuit section with the piezoelectric element 3.

The upper surface of the second package 2 is provided with an upper electrode 2A at a portion corresponding to the lower electrode 1A of the first package 1.
A is electrically connected to a terminal for connecting to the piezoelectric element 3 on the electronic component 4.

Further, a lower electrode 2B is provided on the lower surface portion of the second package 2. This lower electrode 2B
Is connected to a terminal on the electronic component 4 for taking out an output signal from the oscillation circuit section described above, and is also connected to a terminal for adjusting the oscillation circuit section described above. It is also electrically connected to a power supply terminal (not shown) provided for supplying power to the component 4. Also,
The lower electrode 2B is also used as a terminal for adjusting the oscillation circuit section by being electrically connected to a terminal on the electronic component 4, and can be electrically connected to a mother board (not shown).

In the second package 2, the MIM capacitor is an upper electrode 2A for joining with the first package 1.
It is formed at a position extremely close to the oscillation circuit section under the grounding electrode (not shown). With this configuration, the noise component can be promptly removed, and the parasitic capacitance generated between the signal electrode in the upper electrode 2A and the ground pattern in the second package 2 can be suppressed as much as possible. VCXO (Voltage Cont
It is possible to improve the oscillation starting margin of the rolled Crystal Oscillator) part and widen the variable sensitivity.

After the electronic component 4 is mounted in the concave portion 21, by wire bonding in this embodiment, a wire 5 such as a gold wire is used to form an electrode on the electronic component 4 side and a substrate on the second package 2 side. The electrode pattern is electrically connected. The electronic component 4 thus connected is molded with an appropriate resin 6 and is sealed together with the recess 21. Further, a ground pattern (not shown) is provided on the next layer of the mounting surface of the electronic component 4. In addition, at the portion where the wire 5 is connected to the second package 2, one electrode of the MIM capacitor serving as the above-mentioned bypass capacitor is formed.

Therefore, in the piezoelectric oscillator of this embodiment,
When adjusting the frequency, the first package 1 and the second package 1
This is performed by a signal from the mother board in a state where the package 2 and the mother board are electrically connected. In addition, if it is discovered in a later process that a frequency shift has occurred due to a writing error in the adjustment value, a measurement error, or a change in the environment during this adjustment, readjustment is possible and it is handled as a defective product and not discarded. I will be done.

In this embodiment, the wire bonding mounting method is used to connect the second package 2 and the electronic component 4, but a flip chip mounting method may be used. This flip-chip mounting method makes the height of the second package 2 lower than that of the wire bonding mounting method, and satisfies the demand for a low profile.
Area is large and does not meet the demand for smaller area.
The mounting method may be selected according to the priority of height and area.

[Second Embodiment] Next, a second embodiment will be described with reference to FIGS. In this embodiment, the same parts as those in the first embodiment are designated by the same reference numerals to avoid redundant description. In the second embodiment, unlike the first embodiment, the second package 7 does not have a recess on the lower surface, and has a flat bottom surface.
The electronic component 4 is directly mounted. Further, solder balls 8 are formed on the lower electrodes 7B on the lower surface of the second package 7, and the frequency is adjusted by adjusting the solder balls 8 of the first package 1, the solder balls 8 of the second package 7, and the mother board. Is electrically connected to each other, and is performed by a signal from the mother substrate.

In this embodiment, the second package 7 and the mother board are electrically connected to each other through the solder balls 8. However, the present invention is not limited to this, and the second package 7 and the mother board may be connected to each other. Any conducting means may be used as long as it is electrically connected while ensuring a constant distance between them.

[0032]

As described above, according to the present invention, the piezoelectric element, the first package having the electrode electrically connected to the piezoelectric element on the bottom surface, and the electronic device such as a semiconductor integrated circuit in the bottom surface or the recessed portion of the bottom surface. A top surface and a bottom surface on which components are mounted and which is electrically connected to an electronic component; and a second package made of a laminated ceramic that incorporates a capacitor; a bottom electrode of the first package and an upper electrode of the second package; With the configuration in which and are electrically connected, an oscillator having stable characteristics with respect to noise and the like can be configured, and high reliability and high quality can be realized.

Further, according to the present invention, even if either the first package or the second package is a defective product, only the defective product can be replaced. It is possible to improve the mass productivity and productivity because it is rational and economical because there is no need to dispose of it.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a piezoelectric oscillator according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a state where the piezoelectric oscillator shown in FIG. 1 is viewed from the bottom.

3 is a sectional view taken along line III-III in FIG.

FIG. 4 is an exploded perspective view showing a piezoelectric oscillator according to a second embodiment of the present invention.

5 is a perspective view showing a state where the piezoelectric oscillator shown in FIG. 4 is viewed from the bottom.

6 is a cross-sectional view taken along line VI-VI of FIG.

FIG. 7 is a cross-sectional view showing the internal structure of a conventional piezoelectric oscillator.

FIG. 8 is a cross-sectional view showing the internal structure of another conventional piezoelectric oscillator.

[Explanation of symbols]

1st package 1A lower electrode 2 Second package 2A upper electrode 2B lower electrode 21 recess 3 Piezoelectric element (crystal unit) 4 electronic components 5 wires 6 (Molding) resin 7 Second Package 8 solder balls

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akihiko Otani             3-1, Tsunashima-Higashi 4-chome, Kohoku-ku, Yokohama-shi, Kanagawa             Matsushita Communication Industry Co., Ltd. F-term (reference) 5J079 AA04 BA39 BA43 HA07 HA09                       HA28 HA29 KA05

Claims (3)

[Claims] 1. A first package having a piezoelectric element built-in and having an electrode on the bottom surface for conducting the piezoelectric element, and an electrode for accommodating and mounting an electronic component in a recessed portion on the bottom surface for electrically connecting to the electronic component. A second package made of a laminated ceramic which is provided on the top and bottom surfaces and has a built-in capacitor; and a bottom electrode of the first package and an upper electrode of the second package are electrically connected. Piezoelectric oscillator. 2. A first package having a piezoelectric element built-in and having electrodes on the bottom surface for conducting with the piezoelectric element, and an electronic component mounted on the bottom surface and having electrodes on the top surface and the bottom surface for conducting with the electronic component. A second conductive multilayer bump that forms a conductive bump for connection on the bottom electrode and has a built-in capacitor
And a bottom electrode of the first package and an upper electrode of the second package are electrically connected to each other. 3. An electronic component, such as a semiconductor integrated circuit, provided for adjusting an oscillation circuit section including a piezoelectric element in the first package and a semiconductor integrated circuit in the second package. The piezoelectric oscillator according to claim 1 or 2, wherein an electrode that is electrically connected to a terminal is provided on the bottom surface of the second package, and the electrode and the mother substrate of the terminal are electrically connectable.