JP2006050282A - Joined type surface-mounting crystal oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-mounting oscillator for temperature compensation in which bonding strength is enhanced. <P>SOLUTION: The joined type surface-mounting crystal oscillator includes a quarts resonator, in which a quarts piece formed by AT cut is tightly sealed and which has a terminal for a resonator at four corners of the bottom face, a recessed mounting substrate which has a junction terminal connected with the terminal for a resonator and having a planar outer shape smaller than the terminal for a resonator on the upper face of a frame wall, and also, has a write terminal on the outer peripheral side face, and an IC chip composed by integrating an oscillation circuit and a temperature compensation circuit which are stored in the mounting substrate. The opening face side of the mounting substrate is connected to the bottom face of the quarts resonator by soldering. The junction terminal is formed so as to straddle from the upper face of the frame wall to the inner peripheral face. Alternatively/and, the write terminal has a reinforcing part extended from the outer peripheral side face of the frame wall to the upper face. A reinforcing terminal is formed to the bottom face corresponding to the reinforcing part in the quarts resonator. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface mount crystal oscillator for surface mounting (hereinafter referred to as a surface mount oscillator) that is a junction type, and more particularly to a surface mount oscillator for temperature compensation with increased connection strength.

(Background of the Invention) Since a surface-mounted oscillator is small and lightweight, it is built in a portable electronic device as a frequency and time reference source. One of such devices is one in which a mounting substrate containing an IC chip is bonded to the bottom surface of a crystal resonator.

FIG. 3 is a diagram for explaining one conventional example. FIG. 3 (a) is a front view of a surface-mount oscillator including a section AA in FIG. 3 (c), and FIG. Is a bottom view of the crystal resonator, and FIG. 4C is a plan view of the mounting substrate.

  The surface mount oscillator includes a crystal resonator 1 and a mounting substrate 2. Here, the crystal resonator 1 and the mounting substrate 2 have a planar outer shape having the same dimensions (including errors). The crystal resonator 1 is formed by sealing and enclosing a crystal piece made of AT cut (not shown), and providing a vibrator terminal 3 at the four corners of the bottom surface having end face electrodes formed by through holes (not shown). ) " The vibrator terminal 3 includes, for example, one set of diagonal crystal terminals electrically connected to the crystal piece, and another set of diagonal ground terminals connected to the cover 1A.

  The mounting substrate 2 is made of a concave laminated ceramic composed of a bottom wall 2A and a frame wall 2B, and accommodates an IC chip 4. On the upper surface of the frame wall 2B on the opening surface side, there are joint terminals 5 connected to the respective vibrator terminals 3, and on the four corners of the closed surface, power supply, output, ground, etc., connected to the IC chip 4 are not shown. FIG. 3 (c) having a terminal. The planar outer shape of the junction terminal is smaller than that of the vibrator terminal 3. The side surface of the mounting board 2 has a temperature compensation write terminal 6. The IC chip 4 is formed by integrating at least an oscillation circuit and a temperature compensation circuit (not shown).

  The temperature compensation circuit has a compensation voltage generation circuit for compensating the frequency temperature characteristic of the crystal resonator. The frequency-temperature characteristic of the crystal resonator is a cubic curve having an inflection point near the normal temperature, a minimum value at the high temperature portion, and a maximum value at the low temperature portion. The compensation voltage generation circuit generates a compensation voltage having a temperature voltage characteristic approximate to a quintic function in order to compensate the frequency temperature characteristic with high accuracy. Then, a compensation voltage in response to the ambient temperature detected by the sensor is applied to the voltage variable capacitance element to compensate the frequency temperature characteristic.

  In such a case, the IC chip 4 is fixed to the inner bottom surface of the mounting substrate 2 by ultrasonic thermocompression using the bumps 9. Normally, a resin that protects the circuit function surface to which the IC chip 4 is fixed is injected between the inner bottom surface and the circuit function surface. A so-called underfill 7 is formed.

  Then, the opening surface side of the mounting substrate 2 is joined to the bottom surface of the crystal resonator 1 with solder 8 or the like. Normally, cream solder is applied onto the bonding terminals 5 of the mounting substrate 2 to position and superimpose (place) the quartz crystal resonator 1 and transport the high-temperature furnace. As a result, the cream solder is melted and joined together.

  Thereafter, the temperature compensation data is written to the temperature compensation circuit of the IC chip 4 from the write terminal 6 and the oscillation frequency (nominal frequency) is adjusted. The compensation voltage generation circuit of the temperature compensation circuit generates a compensation voltage approximated to a quintic function determined based on the temperature compensation data for each surface mount oscillator.

(Problems of the prior art) However, the surface-mount oscillator having the above-described configuration has a problem that the frame width of the mounting substrate 2 becomes smaller as the miniaturization progresses, and the bonding strength with the crystal resonator 1 decreases. This is caused by compensating the frequency temperature characteristic as a quintic function approximation. That is, as the order of the frequency temperature characteristic is increased to compensate, the number of elements of the temperature compensation circuit is increased and the IC chip is increased in size, so that the frame width is reduced accordingly and the connection strength is lowered.

  For example, when the frequency temperature characteristic is a curve approximating a cubic function, the planar outer shape of the IC chip is approximately 1.7 × 1.4 mm, and when the curve is approximating a quintic function, it is 2.0 × 1.4 mm. Accordingly, the width of the frame wall 2B corresponding to this is reduced, and the bonding strength is reduced.

  In addition, for example, it is conceivable to increase the bonding strength by forming a so-called solder fillet on the side surface of the crystal resonator 1 by making the planar outer shape of the crystal resonator 1 smaller than the mounting substrate 2. The planar outer shape of 2 is enlarged to prevent downsizing.

An object of the present invention is to provide a surface-mount oscillator for temperature compensation with increased bonding strength.

  According to the present invention, in the claims (Claim 1), a quartz crystal unit having an AT cut hermetically sealed and having a transducer terminal at the four corners of the bottom is connected to the transducer terminal. A concave mounting board having a joining terminal having a planar outer shape smaller than the vibrator terminal on the upper surface of the frame wall and a writing terminal on the outer peripheral side surface, and an oscillation circuit and a temperature compensation circuit housed in the mounting board. An integrated IC chip, and a crystal oscillator for surface mounting in which an opening surface side of the mounting substrate is connected to the bottom surface of the crystal resonator by soldering. The structure is formed across the surface.

  According to the third aspect of the present invention, a quartz crystal unit having a crystal piece made of AT cut and hermetically sealed with a crystal terminal having a crystal terminal at the four corners of the bottom surface, and the transducer terminal connected to the crystal terminal A concave mounting board having a junction terminal having a smaller planar outer shape on the upper surface of the frame wall and a writing terminal on the outer peripheral side surface, and an IC chip in which an oscillation circuit and a temperature compensation circuit housed in the mounting board are integrated A crystal oscillator for surface mounting in which the opening surface side of the mounting substrate is connected to the bottom surface of the crystal resonator by solder, and the write terminal has a reinforcing portion extending from the outer peripheral side surface of the frame wall to the upper surface. The crystal unit has a configuration in which a reinforcing terminal is formed on a bottom surface corresponding to the reinforcing portion.

  According to the first aspect of the present invention, since the vibrator terminal and the joining terminal are joined to each other by solder at the upper surface and the inner peripheral surface of the frame wall, the joining strength between them can be increased. According to the second aspect of the present invention, since the reinforcing portion that extends the writing terminal on the side surface of the frame wall to the upper surface is bonded to the vibrator terminal by solder, the bonding strength between the two can be increased.

  According to a second aspect of the present invention, the writing terminal according to the first aspect has a reinforcing portion extending from the outer peripheral side surface of the frame wall to the upper surface, and the crystal resonator has a reinforcing terminal on a bottom surface corresponding to the reinforcing portion. It is set as the structure formed. Thereby, since it is the structure which took in both the invention of Claim 1 and Claim 3, the joint strength of a crystal oscillator and a mounting board | substrate can further be raised.

  In the fourth aspect, the temperature compensation circuit according to the first or third aspect approximates and compensates the frequency temperature characteristic of the crystal resonator by a quintic function. Thereby, since the IC chip becomes large, the configuration according to claim 1 is particularly suitable.

  FIG. 1 is a view of a surface-mount oscillator for explaining a first embodiment of the present invention. FIG. 1 (a) is a side view of a mounting board including a section AA in FIG. 1 (b), and FIG. FIG. 3C is a partially enlarged side view of the surface-mount oscillator including the BB cut in FIG.

  As described above, the surface-mount oscillator is formed by bonding the opening surface side of the mounting substrate 2 having the bonding terminals 5 to the bottom surface of the crystal resonator 1 having the resonator terminals 3 at the four corners by the solder 8 (previous first). (See Figure 3). As described above, the IC chip 4 accommodated in the mounting substrate 2 is also integrated with at least an oscillation circuit and a temperature compensation circuit that approximates and compensates the frequency temperature characteristics of the crystal resonator by a quintic function. .

  The junction terminal 5 here is formed over the inner peripheral surface (inner wall surface) from the upper surface of the frame wall 2B. Specifically, it is formed across the inner peripheral surface (inner wall surface) of the adjacent side from the upper surface of each corner in the frame wall 2B. The planar outer shape of the junction terminal 5 is similarly smaller than that of the vibrator terminal 3.

  With such a configuration, the cream solder applied between the vibrator terminal 3 and the junction terminal 5 at each corner portion is melted in the high-temperature furnace from the opposing surfaces of the inside of the frame wall 2B. It flows into the peripheral surface and is applied. Therefore, since the solder between the vibrator terminal 3 and the joining terminal 5 is joined not only to the opposing surface but also to the inner peripheral surface, the joining strength is increased. In short, the vibrator terminal 3 and the joining terminal 5 form a so-called solder fillet on the inner peripheral surface to increase the joining strength.

  Since the solder fillet is formed on the inner peripheral surface of the mounting substrate (frame wall), the solder fillet is not exposed to the outer peripheral surface, thereby preventing contact with other electronic elements or adhesives on the set substrate. Thereby, for example, a change in frequency can be prevented and reliability can be improved. For example, when the resin for protecting the IC chip mounted on the set substrate adheres to the junction terminal 5, the oscillation frequency changes.

  FIG. 2 is a diagram for explaining a second embodiment of the present invention. FIG. 2 (a) is a front view of a surface-mount oscillator including a section AA in FIG. 2 (c), and FIG. A bottom view of the vibrator and FIG. 10C are plan views of the mounting substrate. In addition, description of the same part as 1st Example is abbreviate | omitted or simplified.

  In the second embodiment, the electrically independent reinforcing terminal 3A is provided between the long-side vibrator terminals 3 on the bottom surface of the crystal vibrator 1 (FIG. 2 (b)). Further, the writing terminal 6 provided on the side surface of the mounting substrate 2 is extended to the upper surface of the frame wall 2B by a through hole (not shown) to form a reinforcing portion 6A (FIG. 3C). The reinforcing terminal 3 </ b> A and the reinforcing portion 6 </ b> A are joined together with the vibrator terminal 3 and the joining terminal 5.

  With such a configuration, both the crystal resonator 1 and the mounting substrate 2 are bonded as 6 terminals, so that the bonding strength between them can be increased. In this case, since the reinforcing terminal 3A of the crystal resonator 1 is electrically independent, no problem occurs even if it is connected to the reinforcing portion 6A of the writing terminal 6.

(Other matters) In the above embodiment, the first embodiment and the second embodiment are described separately. However, the bonding strength may be further increased by combining both configurations. Although the temperature compensation circuit compensates the frequency temperature characteristic approximated to a quintic function, it can be applied to the case of a frequency temperature characteristic approximated to a general cubic function.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure of the surface mount oscillator explaining 1st Example of this invention, The figure (a) is a side view of the mounting board | substrate containing the AA cross section of the figure (b), The figure (b) is the top view. FIG. 5C is a partially enlarged side view of the surface-mount oscillator including the BB cutting in FIG. 2A and 2B are diagrams for explaining a second embodiment of the present invention, in which FIG. 1A is a front view of a surface-mount oscillator including a cross section AA in FIG. 1C, and FIG. FIG. 1C is a plan view of the mounting substrate. FIG. 2A is a front view of a surface-mount oscillator including a cross section AA in FIG. 1C, FIG. 1B is a bottom view of the crystal unit, and FIG. c) is a plan view of the mounting substrate.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Crystal oscillator, 2 Mounting board, 3 Oscillator terminal, 4 IC chip, 5 junction terminal, 6 Write terminal, 7 Underfill, 8 Solder 9 Bump.

Claims (4)

  A crystal resonator having a crystal piece made of AT cut and having a resonator terminal at the four corners of the bottom, and a joint terminal having a planar outer shape smaller than the resonator terminal connected to the resonator terminal A concave mounting board having a writing terminal on an outer peripheral side surface on the upper surface of the frame wall; and an IC chip in which an oscillation circuit and a temperature compensation circuit housed in the mounting board are integrated. A crystal oscillator for surface mounting in which the opening surface side of the mounting substrate is connected by soldering, wherein the joining terminal is formed from the upper surface of the frame wall to the inner peripheral surface.   2. The surface-mounting device according to claim 1, wherein the writing terminal includes a reinforcing portion extending from an outer peripheral side surface of the frame wall to an upper surface, and the crystal resonator has a reinforcing terminal formed on a bottom surface corresponding to the reinforcing portion. Crystal oscillator.   A crystal resonator having a crystal piece made of AT cut and having a resonator terminal at the four corners of the bottom, and a joint terminal having a planar outer shape smaller than the resonator terminal connected to the resonator terminal A concave mounting board having a writing terminal on an outer peripheral side surface on the upper surface of the frame wall; and an IC chip in which an oscillation circuit and a temperature compensation circuit housed in the mounting board are integrated. In the crystal oscillator for surface mounting in which the opening surface side of the mounting substrate is connected by solder, the write terminal has a reinforcing portion extending from the outer peripheral side surface of the frame wall to the upper surface, Is a crystal oscillator for surface mounting in which a reinforcing terminal is formed on the bottom surface corresponding to the reinforcing portion.   4. The surface-mount crystal oscillator according to claim 1, wherein the temperature compensation circuit compensates by approximating a frequency temperature characteristic of the crystal resonator by a quintic function.

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