JP2000252747A - Crystal oscillator and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute a surface mount type crystal oscillator thin and to facilitate temperature characteristic adjusting operation by providing a case- contained crystal vibrator fitted to a flexible substrate, electronic components fitted on the other surface of the substrate, and a rigid frame body which is adhered to the other surface while surrounding the electronic components, etc. SOLUTION: One flexible substrate 1 having wiring patterns formed on both its surfaces is used and the case-contained crystal vibrator 2 which is formed in a different process is fitted to its one surface, the electronic components are fitted to the other surface, and the outer periphery is surrounded with the rigid frame body 4 having a wiring pattern corresponding to the flexible substrate 1. Consequently, the crystal vibrator 2 and electronic components are mounted on the different surfaces of the flexible substrate 1 to the electronic components having effect on the characteristics of the crystal vibrator 2. Further, the case-contained crystal vibrator 2 which is manufactured in the different process and has its function guaranteed is used, so defects caused when the crystal vibrator 2 is fitted can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a surface mount type crystal oscillator in which a crystal unit is mounted on a surface of a circuit board and a method of manufacturing the same.

[0002]

2. Description of the Related Art A crystal oscillator using a crystal oscillator has been conventionally used as a reference oscillator of a frequency or a clock of an electronic device. In particular, in recent years, demand for crystal oscillators for mobile communication such as portable wireless devices has been increasing. As this crystal oscillator for mobile communication, a small, thin, surface-mountable crystal oscillator is required. In addition, a crystal oscillator having high reliability and high accuracy is required, and in particular, a crystal oscillator having a stable oscillation frequency with respect to a temperature change is required.

Assuming that the oscillation frequency is stable against this temperature change, a temperature-compensated crystal oscillator (TCXO, Temper
ature-Compensated Crystal Oscillator). This temperature-compensated crystal oscillator, along with the crystal oscillator, ROM
(Read Only Memory), electronic functional components such as capacitors are mounted on the substrate of the crystal oscillator, and the electronic functional components are used to control the frequency temperature coefficient to be almost zero based on the measured temperature characteristics of the crystal unit. Is what you do. There is known a technique of actually operating a crystal oscillation circuit, giving a temperature change, and writing a control constant in a ROM while observing an oscillation frequency to adjust the frequency-temperature characteristic.

[0004] The following technologies are known as surface-mounted crystal oscillators in which these electronic functional components are mounted on a substrate together with a crystal oscillator to reduce the size and thickness, and are mounted on a substrate of an electronic device.

In the first prior art, an integrated circuit, a capacitor, and the like are mounted as electronic functional components on one surface of a ceramic substrate together with a quartz oscillator (for example, Japanese Patent Application Laid-Open No. Hei 6-232631). FIG. 12 shows this first prior art. As shown in FIG.
A quartz oscillator is mounted on the same surface of a ceramic substrate having a concave portion, and an integrated circuit and a ceramic capacitor are separately mounted.

In the first prior art, since the crystal oscillator and the electronic functional component for controlling the crystal oscillator are mounted on the same substrate, there is an advantage that the thickness of the crystal oscillator itself can be reduced. However, it is necessary to mount the quartz oscillator on the concave portion of the ceramic substrate provided with the concave portion, and the attaching operation requires precise work, and the quartz oscillator is likely to be defective, and the production yield is deteriorated. In addition, since the crystal unit is mounted on the substrate in the same room as the electronic functional component, there is a problem that the characteristics of the crystal unit change due to the mounting of the electronic functional component. In addition, when an electronic functional component is mounted on a ceramic substrate by an automatic machine, a defective product may be generated.

As a second prior art, a quartz oscillator enclosed in a sealed container is attached to one surface of a ceramic substrate,
There is an electronic functional component mounted on another surface (for example, Japanese Patent Application Laid-Open Nos. 7-106891 and 7-106901). FIG. 13A shows this second prior art.
And (b). In the second prior art, since the crystal oscillator and the electronic functional component are mounted on different surfaces of the substrate, there is no problem that the crystal oscillator is affected by the electronic functional component. However, when the electronic functional component is mounted on the ceramic substrate, a problem of poor mounting is likely to occur, and there is a problem that the yield is deteriorated. In recent years, the mounting of the integrated circuit on the substrate has been performed by FDB (face down bonding) technology.
A technique of attaching an integrated circuit directly to a wiring terminal of a substrate by an automatic machine in the form of thermocompression has been adopted. In this FDB technology, the substrate and the integrated circuit need to be parallel to each other with considerable precision. However, in the case of a ceramic substrate, the integrated circuit is slightly inclined with respect to the attached integrated circuit due to a slight distortion in a manufacturing process. In such a case, the mounting of the integrated circuit may be defective. Further, in the second conventional technique, the mounting of the integrated circuit and other electronic functional components and the mounting of the crystal oscillator are performed separately, and if a defect occurs in either the crystal oscillator or the electronic functional component, Even if one of the products is non-defective, the yield is poor because the product is defective.

Further, in the prior art, a crystal oscillator and an electric functional component are mounted on each substrate to complete a crystal oscillator, and then the temperature characteristics are measured for each crystal oscillator and the temperature characteristics are measured. It is necessary to write data for adjusting the data into the integrated circuit. It is necessary to provide a terminal for measuring temperature characteristics for each of the crystal oscillators and writing characteristic compensation data separately from the input / output terminals (power supply, ground, oscillation output) of the crystal oscillator. For example, Japanese Patent Application Laid-Open Nos. 7-1068901 and 7-10
As in the characteristic evaluation pad of the piezoelectric vibrator disclosed in Japanese Patent Application Laid-Open No. 6901, a characteristic evaluation is performed to set characteristic compensation data and then embedded by potting, or used by a user between input / output terminals provided on a substrate as it is. After a small characteristic evaluation terminal is provided, the characteristic evaluation is performed using the characteristic evaluation terminal after the crystal oscillator is assembled, and characteristic compensation data is written. However, providing such a characteristic adjustment terminal separately from the input / output terminal of the crystal oscillator is necessary when the user mounts the crystal oscillator on the electronic device substrate, and the input / output terminal of the crystal oscillator and other circuit patterns are not provided. There is a possibility that a problem of causing a short circuit may occur. Further, there is a problem that productivity is not improved when the temperature characteristic is evaluated for each crystal oscillator and data for compensating the temperature characteristic is written.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a surface mount type crystal oscillator which can be formed extremely thin. In addition, we reduced the incidence of defective products in the manufacturing process,
It is an object of the present invention to provide a crystal oscillator capable of improving a manufacturing yield. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a crystal oscillator that is suitable for mass production and that can reduce the manufacturing cost. According to the present invention, the characteristics of each crystal oscillator can be measured while a large number of crystal oscillators are mounted on a thin substrate such as a sheet or a tape, and compensation data can be written for each crystal oscillator. It is an object of the present invention to provide a method for manufacturing a crystal oscillator that can simplify the operation for the above and improve the productivity.

[0010]

SUMMARY OF THE INVENTION The present invention is characterized by a structure in which a surface-mount type crystal oscillator is configured to be extremely thin and a work for adjusting a temperature characteristic can be simplified, and a manufacturing method thereof.

That is, the first feature of the present invention relates to the structure of a crystal oscillator, and includes one flexible substrate,
A quartz oscillator in a case attached to one surface of the substrate; an electronic component attached to the other surface of the substrate; and a rigid frame bonded to the other surface so as to surround the electronic component. It is characterized by the following. The flexible substrate may have a thickness of 0.025 to 0.2 mm.

Using a single flexible substrate having a wiring pattern formed on both surfaces, a quartz oscillator in a case formed in a separate process is mounted on one surface thereof, and electronic components are mounted on the other surface thereof. Is surrounded by a rigid frame on which a wiring pattern corresponding to the flexible substrate is formed. With such a structure, the crystal unit and the electronic component are mounted on different surfaces of the flexible substrate, respectively, so that the characteristics of the crystal unit are not affected by the electronic component. In addition, since a cased quartz oscillator manufactured in a separate process and whose functions are guaranteed is used, it is possible to reduce the occurrence of defects that occur when attaching the quartz oscillator.

Further, the flexible substrate is 0.025 to
Since the frame can be formed to have a thickness of 0.2 mm and the frame can be formed to have a thickness of 0.4 to 0.6 mm, the electron formed by bonding the frame to the flexible substrate is formed. The thickness of the component housing can be suppressed to 0.8 mm or less, and the cased quartz oscillator attached to one surface of the flexible substrate is formed to a thickness of 0.7 mm or less. 1.5 overall thickness
It can be formed to a very thin thickness within mm.

A second feature of the present invention relates to a method for manufacturing a crystal oscillator, in which a step of printing a large number of oscillation circuit wirings on both sides of a single flexible substrate and a large number of openings in one surface of the flexible substrate. Bonding a rigid substrate having an opening portion thereof such that a main portion of the wiring is exposed, mounting electronic components in the opening, and respectively corresponding to the opening on the opposite surface of the flexible substrate. The method includes a step of mounting one cased quartz resonator and a step of punching or cutting the periphery of the opening together with the flexible substrate.

Before the punching or cutting step, it is preferable to include a step of applying a current to the wiring and applying a temperature change while operating the oscillation circuit to adjust a frequency temperature characteristic for each oscillation circuit.

First, a large number of oscillation circuit wirings and wirings including socket terminals for supplying current to each of the large number of oscillation circuit wirings are printed on both sides of one flexible substrate. A sheet-shaped or tape-shaped substrate can be used as the flexible substrate. The socket terminals and their wirings are configured so that a plurality of oscillation circuit wirings can be simultaneously energized as one block, and the socket terminals are arranged in a plurality of blocks and the socket terminals are arranged at one end of the board. Arrange so that it is aligned.

Next, a rigid substrate having a large number of openings formed in a separate step is adhered to one surface of the flexible substrate thus formed such that the main parts of the oscillation circuit wiring are exposed at the openings, respectively. Join mechanically.
This opening is inside the frame.

Next, electronic components are mounted on the main portions of the wiring for the oscillation circuit of the flexible substrate appearing in the openings, respectively, and a filler is injected into the space between the openings and the electronic components to be fixed.

Furthermore, a case-filled crystal resonator formed in a separate process is mounted on the opposite surface of the flexible board on which the electronic components are mounted, corresponding to the opening of the frame.

Here, current is applied through a socket terminal formed on the flexible substrate, a temperature change is given while operating the oscillation circuit, frequency temperature characteristics are collected for each oscillation circuit, and the temperature compensation data is obtained. Process and write to electronic circuit. To collect the frequency temperature characteristics and write the temperature compensation data, the characteristics of each crystal oscillator are measured while a large number of crystal oscillators are mounted on a thin flexible board in the form of a sheet or tape, and each crystal oscillator is measured. Since the temperature compensation data can be written in the memory, the operation for adjusting the temperature characteristics is extremely simplified, and the productivity can be improved.

After the adjustment of the frequency temperature characteristic and the writing of the compensation data, the periphery of the opening of the rigid substrate is punched together with the flexible substrate or cut out as a product by a die saw or the like.

[0022] Such a manufacturing method can automate each step, and therefore is suitable for mass production and can produce a highly reliable product at a low manufacturing cost.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

[0024]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an enlarged perspective view showing the shape of the embodiment of the present invention, and FIG.
FIG. 3 is an exploded perspective view showing the configuration of the embodiment of the present invention, FIG. 3 is an AA enlarged sectional view of FIG. 1 showing the internal structure of the embodiment of the present invention,
FIG. 4 is an enlarged perspective view of the electronic component housing portion according to the embodiment of the present invention as viewed from the bottom side.

The embodiment of the present invention comprises a single flexible substrate 1, a cased crystal oscillator 2 attached to one surface of the flexible substrate 1, and an electronic component attached to the other surface of the flexible substrate 1. A rigid frame 4 is attached to the other surface so as to surround the electronic component. The thickness t1 of the flexible substrate 1 is 0.025-0.
It is formed to 2 mm. In this embodiment, an example in which one integrated circuit 3a and two chip capacitors 3b are mounted as electronic components will be described.

A large number of oscillation circuit wirings and communication lines 11 for writing temperature compensation data and the like are printed on both sides of the flexible substrate 1, and a case-mounted crystal resonator 2 is mounted on the upper surface thereof. Further, there are provided connection terminals 12 which are electrically connected to a plurality of (four in this embodiment) electrodes provided on the cased crystal resonator 2 respectively. For the flexible substrate 1, for example, a resin such as polyimide is used.

The frame 4 is formed of a rigid board made of epoxy resin, and a space 41 accommodates the integrated circuit 3a and the chip capacitor 3b. Further, a plurality of (four in this embodiment) external connection terminals 42 are provided at the bottom thereof, and an end face external electrode portion 43 for connecting the external connection terminals 42 to the flexible substrate 1 is provided. On the side surface located at the external connection terminal 42, a side surface through-hole 44 serving as a pool of a bonding agent (solder) is formed.

The quartz oscillator 2 in the case is
1 is provided, and a connection terminal 22 which is electrically connected to the connection terminal 12 of the flexible substrate 1 and is mechanically fixed by high-temperature solder is provided at the bottom thereof.

As an example of the size of the crystal oscillator 2 in a case, the long side L shown in FIG. 1 is 4.8 mm to 5.2 m.
m, the short side D is formed to be 2.8 mm to 3.2 mm, and the size of the flexible substrate 1 and the frame 4 is substantially equal to the size of the crystal unit 2 in the case, or more than that. It is formed large. The thickness t2 of the frame 4 shown in FIGS. 1 and 3 is formed to be 0.4 to 0.6 mm. Therefore, the crystal unit 2 in the case is 0.7
mm and the flexible substrate 1 is formed to have a thickness of 0.025 to 0.2 mm, so that the crystal oscillator can be realized as a product having an extremely thin thickness of 1.5 mm or less.

Here, a method of manufacturing the crystal oscillator according to the embodiment of the present invention will be described.

First, a sheet-like wiring pattern in which a plurality of flexible substrates 1 are arranged as shown in FIG. 5 is designed. Based on this wiring pattern, as shown in FIG. 6, a large number of oscillation circuit wirings are printed on both surfaces of one sheet-like flexible substrate 10.

Next, as shown in FIG. 7, a rigid sheet-like rigid substrate 4 which is manufactured in a separate process to form the frame 4 is formed.
0 is electrically and mechanically joined to the sheet-like flexible substrate 10. A large number of openings 45 and side through holes 44 are formed in advance in the sheet-like rigid substrate 40. A plurality of (four in this embodiment) end face external electrode portions 43 shown in FIG. 3 and a plurality of (four in this embodiment) external connection terminals 42 shown in FIGS. Further, a plurality of socket terminals 46 are formed. The opening 45 of the sheet-like rigid board 40 is joined to a position where the main part of the wiring of the sheet-like flexible board 10 appears.

Next, as shown in FIG. 8, the electronic components of the integrated circuit 3a and the chip capacitor 3b are mounted on the sheet-like flexible substrate 10 exposed in each of the openings 45 with a conductive adhesive. Filling and fixing an electrically insulating synthetic resin.

Further, in the next step, as shown in FIG. 9, the case 45 is turned over so that the surface of the opening 45 faces downward, and the quartz oscillator 2 in the case is placed on the connection terminals 12 formed on the sheet-like flexible substrate 10. Is mounted, and the connection terminal 12 and the connection terminal 22 of the cased crystal unit 2 are joined by high-temperature solder.

In this state, as shown in FIG. 10, current is supplied to the wiring for the oscillation circuit through the socket terminal 46 to change the temperature while operating the oscillation circuit. The data is collected, processed into temperature compensation data, and the data is written.

After the completion of the writing of the temperature compensation data,
As shown in FIG. 11, the periphery of the opening 45 of the sheet-like rigid board 40 is punched together with the main wiring portion of the sheet-like flexible board 10, and cut out as individual products with the case-attached crystal resonator 2 attached. Instead of this punching, it can be cut out with a die saw or the like.

In the present embodiment, an example using a sheet-shaped flexible substrate and a rigid substrate serving as a frame has been described. However, a tape-shaped flexible substrate and a rigid substrate can be used to manufacture the same. The effect of can be obtained.

[0038]

As described above, according to the present invention, the crystal oscillator can be made extremely thin, the occurrence rate of defective products in the manufacturing process can be reduced, the manufacturing yield can be improved, and the manufacturing cost can be reduced. Can be lower. In addition, temperature characteristics can be adjusted by measuring the characteristics of each crystal oscillator and writing compensation data for each crystal oscillator while many crystal oscillators are mounted on a thin sheet or tape-shaped substrate. Work can be simplified and productivity can be improved.

[Brief description of the drawings]

FIG. 1 is an enlarged perspective view showing a shape of an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing the configuration of the embodiment of the present invention.

FIG. 3 is an enlarged sectional view taken along the line AA of FIG. 1 showing the internal structure of the embodiment of the present invention.

FIG. 4 is an enlarged perspective view of the electronic component housing section according to the embodiment of the present invention as viewed from the bottom surface side.

FIG. 5 is a diagram showing an example of the arrangement of sheet-like patterns used in the crystal oscillator according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating a printing process of an oscillation circuit wiring in the manufacture of the crystal oscillator according to the embodiment of the present invention.

FIG. 7 is a view for explaining a bonding step between the flexible substrate and the frame in the manufacture of the crystal oscillator according to the embodiment of the present invention.

FIG. 8 is a view for explaining an electronic component mounting step in manufacturing the crystal oscillator according to the embodiment of the present invention.

FIG. 9 is a diagram illustrating a process of mounting a cased crystal resonator in the manufacture of a crystal oscillator according to an embodiment of the present invention.

FIG. 10 is a view for explaining a frequency temperature step in the manufacture of the crystal oscillator according to the embodiment of the present invention.

FIG. 11 is a view for explaining a punching step in manufacturing a crystal oscillator according to an embodiment of the present invention.

FIG. 12 is a perspective view showing a configuration of a first conventional example.

13A and 13B are a cross-sectional view and a bottom view showing a configuration of a second conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flexible board 2 Crystal oscillator in a case 3a Integrated circuit 3b Chip capacitor 4 Frame 10 Sheet-like flexible board 11 Communication line 12, 22 Connection terminal 21 Quartz diaphragm 40 Sheet-like rigid board 41 Space 42 External connection terminal 43 Edge external electrode Part 44 Side through hole 45 Opening 46 Socket terminal

Claims (4)

[Claims] 1. A single flexible substrate, a cased quartz resonator mounted on one surface of the substrate, an electronic component mounted on the other surface of the substrate, and another surface surrounding the electronic component. A crystal oscillator comprising a rigid frame bonded thereto. 2. The thickness of the flexible substrate is 0.02.
2. The crystal oscillator according to claim 1, which is 5 to 0.2 mm. 3. A step of printing a large number of oscillation circuit wirings on both sides of one flexible substrate, and a step of printing a rigid substrate having a large number of openings on one surface of the flexible substrate with the main parts of the wirings at the openings. Bonding, and mounting electronic components in the openings, attaching one case-containing crystal resonator to the opposite surface of the flexible substrate corresponding to the openings, Punching or cutting the periphery together with the flexible substrate. 4. The method according to claim 2, further comprising, before the punching or cutting step, energizing the wiring to apply a temperature change while operating an oscillation circuit to adjust a frequency temperature characteristic for each oscillation circuit. Manufacturing method of crystal oscillator.