JP2001320240A - Piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric oscillator capable of being miniaturized and low in cost. SOLUTION: A temperature compensated crystal oscillator consists of a chip type crystal resonator (piezoelectric resonator) 1 and an IC chip (circuit element) 4 to be attached to a metal lid 2 of the crystal resonator. As for the crystal resonator air-tightly sealed by the metal lid, its electric characteristics are measured through terminals K1 and K2 for measurement, and the circuit element of a required constant is packaged on the metal lid on the basis of the measured result. Then the electrode pad of the crystal resonator and the connection terminal of the IC chip are connected mutually and the IC chip or the like is covered with a resin 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric oscillator used for a communication device such as a portable telephone or an electronic device.

[0002]

2. Description of the Related Art A piezoelectric oscillator generally has a structure in which a piezoelectric vibrator and an integrated circuit element including an amplifier are integrally housed, and further has a voltage control function in which a frequency control function is added to the piezoelectric oscillator. There is a control-type piezoelectric oscillator, a temperature-compensated piezoelectric oscillator to which a temperature compensation function is added, and the like.

[0003]

Heretofore, these quartz oscillators, feedback amplifiers, and circuit elements constituting additional functions have been arranged in a plane on a single substrate. However, due to recent demands for miniaturization of electronic components, mounting on these substrates has been in a direction of higher density and more integration, and miniaturization of the crystal unit itself is also being studied. However, in the case of flat mounting, the mounting area is inevitably limited, and the miniaturization of the crystal unit has the disadvantage that if the size is too small, the parallel capacitance value will decrease, and the amount of frequency variation in the frequency control circuit will decrease. Was.

In order to avoid such a problem, a configuration in which a piezoelectric vibrator and a circuit element are arranged on the front and back of a package substrate has been considered. Japanese Patent Application Laid-Open No. 8-204452 discloses a configuration in which a piezoelectric element and electronic components are arranged on the front and back of a substrate in a temperature compensated oscillator. The package used here has a configuration in which a concave portion is formed on each of the upper and lower portions, and a piezoelectric element and an electronic component are stored in each concave portion. Although such a package is made of ceramic, it is difficult to manufacture such a structure having concave portions on the upper and lower sides, and there has been a problem that cost is excessively high when practically effective manufacturing accuracy is required.

Further, as disclosed in Japanese Patent Application Laid-Open No. 10-70414, a package (a structure in which a ceramic package or a lead frame is resin-molded) for accommodating an integrated circuit element is prepared, and a quartz oscillator is mounted on the package. A mounted configuration is disclosed. In this configuration, the use of a hermetically sealed quartz oscillator has the advantage that the characteristics of the quartz oscillator are not adversely affected.

However, when a plurality of components are stacked, positioning and fixing work are troublesome, and there is a problem that productivity is reduced. In particular, in recent years, downsizing of quartz oscillators has been progressing, and this problem has become apparent. Was. In addition, a package is prepared for an integrated circuit element, and a pad for grounding is also required, so that there is a problem that the manufacturing cost is increased as a whole.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a piezoelectric oscillator which can be reduced in size and inexpensive.

[0008]

According to the present invention, there is provided a piezoelectric oscillator comprising a housing for accommodating a piezoelectric vibrating plate, a bank surrounding the housing, and a circumferential portion provided inside the upper surface of the bank. First
A ceramic package having an electrode pad provided outside the first metal layer and having a piezoelectric vibrator characteristic measuring terminal formed on an outer surface thereof; A piezoelectric vibrating plate on which electrodes are formed;
A second metal layer joined corresponding to the metal layer, a metal lid connected to ground, and a connection electrode mounted on the metal lid and electrically connected to the electrode pad, A piezoelectric oscillator comprising a circuit element forming an oscillation circuit together with the piezoelectric vibration plate, wherein at least the electrode pad, the metal lid, and the circuit element are covered with a resin.

According to the present invention, the electrical characteristics of a piezoelectric vibrator hermetically sealed with a metal lid are measured via a measuring terminal, and necessary circuit elements are set in accordance with the measurement result. Can be mounted on top. For example, when a circuit element having a temperature compensation function is mounted, a circuit element having a constant corresponding to the characteristics of the piezoelectric vibrator can be mounted, and optimal temperature compensation can be performed.

[0010] Since the circuit element is mounted on the metal lid of the piezoelectric vibrator, the earth connection of the circuit element can be facilitated. Further, since the electrode pads, the metal lid, and the integrated circuit are covered with resin, a piezoelectric oscillator can be configured without requiring a new package, a lead frame, and the like for the circuit element.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 to 5, taking a surface-mounted temperature-compensated crystal oscillator as an example. FIG. 1 is an exploded perspective view showing the present embodiment, FIG. 2 is a perspective view after an IC chip (circuit element) is mounted, FIG. 3 is a perspective view showing a resin-coated state, and FIG. FIG. 5 is a bottom view of the internal cross section of the oscillator.

The temperature-compensated crystal oscillator comprises a chip-type crystal oscillator (piezoelectric oscillator) 1 and an IC chip (circuit element) 4 mounted on a metal cover 2 of the crystal oscillator.

The crystal unit 1 is a ceramic package 1
0, and the storage unit 1 formed in the ceramic package 10
A quartz vibrating plate (piezoelectric vibrating plate) 3 housed in a housing 5 and a metal lid 2 for hermetically sealing the quartz vibrating plate 3 are provided.

The ceramic package 10 is made of ceramics such as alumina, and has a rectangular parallelepiped shape with an open upper portion. A first metal layer 11 formed in a circumferential shape is formed on an upper surface 10a of a bank portion around the opening. . The first metal layer 11 is formed by stacking tungsten and nickel using a metallization technique and a plating technique, respectively. A plurality of electrode pads 12 are formed outside the first metal layer 11, and each of the electrode pads 12 is composed of a crystal oscillator, an IC chip, and external lead electrodes 16 formed on the back surface.
17, 18, and 19 are connected appropriately. The storage unit 1
5, support electrodes 13 and 14 (partially not shown) for electrically and mechanically joining the quartz vibrating plate 3 are formed. And are appropriately electrically connected to electrode pads, IC chips, and the like.

In this embodiment, program terminals P1 and P2 are formed on the side surface of the ceramic package 10. The program terminals P1 and P2 are electrically connected to a part of the electrode pad 12. After an IC chip to be described later is connected to the electrode pad by a bonding wire, the program terminals P1 and P2 are connected via the program terminals P1 and P2.
Write data for temperature compensation to the C chip. Of course, when the IC chip does not support such writing, or when writing is not performed, such a terminal becomes unnecessary.

The quartz vibrating plate 3 is a rectangular AT-cut quartz plate. Exciting electrodes 31 and 32 (32 are not shown) are formed on the front and back surfaces, and a conductive resin adhesive ( (Not shown) to one end. The metal cover 2 is a metal plate 2 such as Kovar.
0 is used as a base material, and a metal layer 21 made of nickel or the like is formed corresponding to the metal layer 11. Then, the ceramic package 10 and the metal lid 2 are welded in an inert gas atmosphere or a reduced pressure atmosphere. As a joining method, known seam welding, laser welding, ultrasonic welding, or the like can be used. The metal lid 2 is electrically connected to one of the external lead-out electrodes and is grounded. In the present embodiment, the external lead electrode 18 has a ground function, and is electrically connected to the first metal layer 11, the second metal layer 21, and the metal lid 2.

A measuring terminal K is provided on the bottom of the crystal unit 1.
1 and K2 are formed by a ceramic lamination technique, and the electrical characteristics of a quartz oscillator which is hermetically sealed with a metal lid are first measured via measurement terminals K1 and K2. A circuit element having a necessary constant is mounted on the metal lid according to the measurement result. In this embodiment, a temperature compensation function is incorporated in the IC chip, and optimal temperature compensation can be performed by selecting an optimal IC chip corresponding to the characteristics of the crystal unit. In addition, this temperature compensation complements the above-described data writing to the IC chip, so that more optimized compensation can be performed.

A plurality of connection electrodes 4 are provided on the upper surface of the IC chip 4.
2 and are electrically connected to the metal lid 2 as shown in FIG. 2, and each of the electrode pads 12 formed on the ceramic package is electrically connected to the connection electrode 41 by a bonding wire W. You.

Thereafter, a mold (not shown) is attached to the upper part of the quartz oscillator, and the electrode pads, metal lids and circuit elements are covered with the mold. In this state, for example, an epoxy resin heated to a fluid state is filled with the mold. Inject into a mold and coat resin 5. Note that the temperature compensation data may be written to the above-described IC chip as needed.

In the above embodiment, one IC chip is exemplified as a circuit element, but a plurality of circuit elements may be mounted on a metal lid. The circuit elements are not limited to those constituting the oscillation circuit and the temperature compensating circuit, but may be those constituting a voltage-controlled piezoelectric oscillation circuit.
Further, although the piezoelectric vibrator characteristic measuring terminal is formed on the bottom surface of the piezoelectric vibrator, it may be formed on, for example, the side surface or the upper surface of the bank.

[0021]

According to the present invention, the electrical characteristics of a piezoelectric vibrator hermetically sealed with a metal lid are measured via a measuring terminal, and necessary circuit elements are determined according to the measurement result. Since the piezoelectric oscillator can be mounted on the metal lid, the characteristics of the piezoelectric oscillator can be reliably adjusted.

Further, since the circuit element is mounted on the metal lid of the piezoelectric vibrator and the electrode pads, the metal lid, and the integrated circuit are covered with the resin, the circuit can be formed without requiring a new package, a lead frame, and the like. An element can be mounted. In addition, the grounding of the circuit element can be easily performed via the metal lid, and it is not necessary to provide a separate grounding terminal as in the related art. Therefore, it is possible to obtain a piezoelectric oscillator that can be reduced in size and that is inexpensive.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment.

FIG. 2 is a perspective view showing the embodiment.

FIG. 3 is a perspective view showing the embodiment.

FIG. 4 is an internal cross-sectional view showing the embodiment.

FIG. 5 is a bottom view showing the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quartz crystal oscillator (piezoelectric oscillator) 10 Ceramic package 11 1st metal layer 15 Housing part 2 Metal cover 21 2nd metal layer 3 Quartz crystal plate (piezoelectric plate) 4 Circuit element (IC chip)

Claims (1)

[Claims] A storage portion for storing the piezoelectric vibration plate, a ridge surrounding the storage portion, a first peripheral metal layer provided inside an upper surface of the ridge portion; A ceramic package including an electrode pad provided outside the metal layer, and a piezoelectric vibrator characteristic measuring terminal formed on an outer surface; and a piezoelectric vibrating plate disposed on the housing portion and having an excitation electrode formed thereon. A metal lid connected to the first metal layer and connected to the ground, and a connection electrode mounted on the metal lid and electrically connected to the electrode pad; And a circuit element comprising an oscillation circuit together with the piezoelectric vibration plate, wherein at least the electrode pad, the metal lid, and the circuit element are covered with a resin.