JP2001358426A - Electronic circuit device provided with oscillation circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic circuit device provided with an oscillation circuit which can make higher the mounting density of electronic components than the conventional mounting examples. SOLUTION: An electronic circuit device is constituted in a structure that all electronic components constituting an oscillation circuit comprising a rock crystal oscillator 3 for surface mounting are mounted on the surface of a circuit board 1. Resistors R1 to R4, which are one part of the electronic components constituting the oscillation circuit, are formed by printing to arrange the resistors R1 to R4 under a packaged case 5 for the oscillator 3 on the surface 1A of the board 1. A trimming resistor R5 for function, which cannot be arranged under the oscillator 3, is also formed by printing on the surface 1A. The formation area of an earth pattern 9, which is formed on the rear 1B of the board 1, is made as wide as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic circuit device having an oscillation circuit.

[0002]

2. Description of the Related Art An electronic circuit device having an oscillation circuit such as a TCXO is formed on a circuit board having a front-side circuit pattern formed on a front surface and a back-side circuit pattern including an earth pattern formed on the back surface of the circuit board. It has a structure in which electronic components including a crystal oscillator for surface mounting constituting an oscillation circuit are mounted. In order to increase the mounting density, even in this type of electronic circuit device, electronic components are mounted on the front and back surfaces of a circuit board.

[0003]

However, the conventional structure has a problem that it is difficult to further increase the mounting density.

An object of the present invention is to provide an electronic circuit device provided with an oscillation circuit capable of increasing the mounting density of components as compared with the prior art.

Another object of the present invention is to provide, in addition to the above objects,
It is an object of the present invention to provide an electronic circuit device including an oscillation circuit capable of preventing a change in frequency.

Another object of the present invention is to provide an electronic circuit device provided with an oscillation circuit having excellent insulation characteristics.

Another object of the present invention is to provide an electronic circuit device having an oscillation circuit whose manufacturing cost is low.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a circuit board having a front-side electrode pattern formed on a front surface and a back-side circuit pattern including a ground pattern formed on a back surface, and a circuit board for forming an oscillation circuit. A plurality of electronic components including a surface-mounted crystal oscillator mounted thereon, wherein the surface-mounted crystal oscillator has a structure in which an oscillation element is provided inside an outer case; The object of the present invention is to provide an electronic circuit device having an oscillation circuit mounted on a surface of a circuit board such that a space is provided between the outer case and the surface of the circuit board. According to the present invention, one or more electronic components formed by printing out of the plurality of electronic components are arranged in a region on the surface of the circuit board located below the outer case of the crystal oscillator for surface mounting. The crystal oscillator for surface mounting is mounted on the surface of the circuit board by soldering electrodes for soldering on the surface of the outer case to electrodes provided on the circuit board for mounting.
In this case, a gap or space for insulation is formed between the outer surface of the outer case and the circuit board. In order to reduce the thickness of the entire electronic circuit device, the surface mounting crystal oscillator is mounted with the surface having the largest area facing the front side of the circuit board. However, in this case, since only a small gap is formed between the outer case and the surface region of the circuit board opposed to the outer case, it is impossible to mount electronic components in this region, and the electronic device is placed on the surface of the circuit board. There is a limit to increasing the mounting density when mounting components. Therefore, as in the present invention, even when there is only a small space above the surface area of the circuit board located under the outer case of the crystal oscillator for surface mounting, the thickness of the plurality of electronic components can be reduced. By arranging one or more electronic components formed by printing that can be performed, the electronic components can be arranged in a region that has not been conventionally used, and the mounting density of the electronic components on the circuit board can be increased. This contributes to reducing the size of the electronic circuit device provided with the oscillation circuit.

In particular, it is preferable to use a printed resistor as one or more electronic components arranged in a region on the surface of the circuit board located below the crystal oscillator for surface mounting. Among electronic components that can be formed by printing among electronic components used for an oscillation circuit, a capacitor has a great influence on the determination of the oscillation frequency. Therefore, high accuracy is required to some extent. On the other hand, the resistor has little influence on the variation of the oscillation frequency of the oscillation circuit even if the resistance of each resistor has some variation. Therefore, as in the present invention, the first electrode is arranged in a region on the surface of the circuit board located below the crystal oscillator for surface mounting.
When a printed resistor is used as the above electronic component (an electronic component that cannot be adjusted later and cannot be replaced), even if there is a variation in the resistance value, there is little influence on the variation in the oscillation frequency.

In the conventional electronic circuit device having an oscillation circuit, although there is no problem in product inspection at the time of shipment,
It has been found that when an electronic circuit device having this oscillation circuit is mounted on a motherboard, a problem occurs in that the oscillation frequency of the oscillation circuit fluctuates. As a result of the research conducted by the inventor, the shape of the circuit pattern around the oscillation circuit on the motherboard affects the capacitance component of the electronic components mounted on the back surface of the circuit board of the electronic circuit device, causing the oscillation frequency of the oscillation circuit to fluctuate. I knew it was. Therefore, if a plurality of electronic components are all mounted on the front surface of the circuit board, there is no component affected by the capacitance component on the back surface of the circuit board, and only the ground pattern exists. It is possible to effectively prevent the oscillation frequency from fluctuating due to the influence of the capacitance component change due to the shape of the circuit pattern. There is little effect on noise generated from conventional circuit components, and stable characteristics can be obtained. Considering the influence of the circuit pattern from the motherboard side, it is preferable that the ground pattern be as large as possible.

[0011] Even when the electronic circuit device provided with the oscillation circuit of the present invention is a temperature-compensated crystal oscillator including a temperature compensation circuit, even if the oscillation circuit is a temperature-compensated crystal oscillator, the lower part of the outer case constituting the surface-mounted crystal oscillator is provided. It is preferable to arrange a plurality of resistors formed by printing out of a plurality of electronic components in a region of the surface of the circuit board located at the position (1).

One or more functional trimming resistors formed by printing can be arranged in an area outside the area of the surface of the circuit board. By forming the functional trimming resistor by printing in this way, it is not necessary to mount a normal chip-type functional trimming resistor, so that the number of manufacturing steps and the manufacturing cost can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view schematically illustrating an example of an arrangement state of electronic components on a circuit board when an electronic circuit device including an oscillation circuit according to an embodiment of the present invention is applied to a temperature-compensated crystal oscillator. FIG. 2 is a bottom view of a circuit board used for the temperature-compensated crystal oscillator (an electronic circuit device having an oscillation circuit) according to the embodiment of the present invention. FIG.
1 is a schematic front view of a temperature-compensated crystal oscillator (an electronic circuit device including an oscillation circuit) according to an embodiment of the present invention. 1 to 3, a member denoted by reference numeral 1 is a circuit board.
The circuit board 1 used in this example is a double-sided circuit board (double-sided printed board). This circuit board 1 has a front side circuit pattern (see FIG. 1) on the front side 1A side and the back side 1B side of the circuit board 1 by using a known etching technique on an insulating ceramic substrate having a metal film such as aluminum or gold formed on the front and back surfaces. In FIG. 2, the circuit pattern is not shown) and the back side circuit pattern 2 is formed. As will be described later, the back side circuit pattern 2 constitutes a ground pattern. As shown in FIG. 2, the circuit board 1 has a plurality of through holes 13 having through hole connection portions for electrically connecting predetermined circuit portions of the front side circuit pattern and the back side circuit pattern. Have been. The through-hole connection portion is formed by filling the inner wall surface of the through-hole 13 with a conductive paste or plating.

In FIG. 1, a plurality of electronic components (capacitor, resistor,
Dedicated IC, crystal oscillator, etc.) are mounted. The component indicated by reference numeral 3 among these electronic components is a crystal oscillator for surface mounting. As schematically shown in FIG. 3, the surface mounting crystal oscillator 3 is covered with a metal box-shaped outer case 4, and the inside of the outer case 4 is formed of a rectangular quartz plate. An oscillation element (not shown) is supported so as to be able to vibrate. The outer surface of the outer case 4 in this example has a substantially rectangular back surface 4a having the largest area facing the front surface 1A of the circuit board 1, and a front surface 4b facing the back surface 4a in the thickness direction.
And a pair of end surfaces 4c and 4d located at both ends in the longitudinal direction of the outer case 4, and a pair of side surfaces 4e and 4f. On the back surface 4a of the outer case 4, four soldering electrodes E1 to E4 of a plurality of electrodes included in the front-side circuit pattern formed on the front surface 1A of the circuit board 1 are provided.
Four connection electrodes 5 connected to E4 by solder portions 6
a to 5d are formed. For the formation of the solder portion 6,
Usually, cream solder is used.

As schematically shown in FIG. 3, the size of the gap G formed between the front surface 1A of the circuit board 1 and the back surface 4a of the outer case 4 is determined by the size of the electrode formed on the front surface 1A of the circuit board 1. It is determined by the total value of the thicknesses of E1 to E4, solder portion 6, and connection electrodes 5a to 5d. The size of the gap G is usually about 0.1 mm, which is considerably smaller than the thickness of the smallest chip-shaped electronic component. Therefore, conventionally, no electronic component is arranged in this gap.
The present invention focuses on the fact that even a small gap can be arranged as long as it is an electronic component having a small thickness such as a printed resistor, etc. Print resistors R1 to R4 formed by printing are arranged in a region of the front surface 1A of the circuit board 1 facing the back surface 4a of the outer case 4. As a result, the mounting density of electronic components on the surface 1A of the circuit board 1 is higher than before. In this example, the function trimming resistor R5 disposed in a region outside the front surface 1A of the circuit board 1 facing the back surface 4a of the outer case 4 of the surface mounting crystal oscillator 3 is also formed by a printed resistor. is there. Therefore, in this example, the printed resistors R1 to R4 and the resistor for functional trimming R5 can be formed together, and the number of steps for mounting electronic components on the front surface 1A of the circuit board 1 can be reduced. The formation of the printed resistor may be realized by a well-known method, and the surface of the printed resistor is covered with an insulating coat except for the resistor portion of the resistor R5 for functional trimming. Therefore, even if the printed resistors R1 to R4 come into contact with the back surface 4a of the outer case 4 of the crystal oscillator 3 for surface mounting, an electrical short circuit does not occur.

On the surface 1A of the circuit board 1, a region outside the region opposed to the back surface 4a of the outer case 4 of the crystal oscillator 3 for surface mounting is provided for forming an oscillation circuit including a temperature compensation circuit. Other electronic components used: capacitor C
1 to C4, function trimming resistor R5 and oscillation IC
1 and the like are arranged. In addition, the number, type, and arrangement position of each electronic component constituting the oscillation circuit shown in FIG. 1 are schematically shown, and the number, type, and arrangement position of the electronic components constituting the actual oscillation circuit are as follows. Are different. As shown in FIG. 3, these other electronic components are also connected by soldering via a solder portion 6 to a plurality of electrodes E provided on the surface 1 </ b> A of the circuit board 1. I have.

On the back surface 1B of the circuit board 1, connection terminal electrodes 7 for electrically and physically connecting the circuit board 1 and a motherboard (not shown) of an electronic device such as a mobile phone are provided.
A back side circuit pattern 2 including a, 7b, 7c, 7d, a wiring portion 7e, and a ground pattern 9 is formed.
In this example, no electronic components constituting the oscillation circuit are mounted on the back side of the circuit board 1. The ground pattern 9 has a size occupying most of the surface area of the back surface 1B of the circuit board 1, and is electrically connected to the ground terminal of the surface mounting crystal oscillator 3 mounted on the front surface 1A of the circuit board 1. Connected. The front-side circuit pattern formed on the front surface 1A of the circuit board 1 and the back-side circuit pattern 2 formed on the back surface 1B of the circuit board 1 are electrically connected by through-hole conductive portions formed in the plurality of through-holes 13. It is connected to the. As described above, in FIG. 1, the shapes of the front-side circuit patterns and the through holes 13 that are electrically connected to the rear-side circuit patterns 7 are omitted.

As described above, when a plurality of electronic components constituting an oscillation circuit are arranged only on the front surface 1A of the circuit board 1, and the ground pattern 9 having as large an area as possible is formed on the back surface 1B of the circuit board 1, the circuit When the substrate 1 is mounted on a motherboard, it is less susceptible to a change in capacitance component due to a pattern shape arranged on the motherboard side.
It is possible to effectively prevent the oscillation frequency of the oscillator from fluctuating due to noise. Even when all the electronic components constituting the oscillation circuit are mounted on the front surface 1A of the circuit board 1, the circuit board 1 facing the back surface 4a of the outer case 4 of the crystal oscillator 3 for surface mounting as in the present invention. If electronic components formed by printing are arranged on the surface area, the surface 1 of the circuit board 1
The mounting density on A can be increased.

By forming the function trimming resistor R5 by a printing method, the mounting of components can be reduced as compared with the case where a conventional chip-type function trimming resistor is used. Thereby, the mounting density can be further increased. Note that the same effect can be obtained as long as the number of resistors arranged below the surface-mounting crystal oscillator 3 is one or more.

[0020]

According to the present invention, at least one electronic component formed by printing is arranged in the area of the surface of the circuit board located under the outer case of the crystal oscillator for surface mounting, so that it can be used conventionally. Since the electronic components can be arranged in the area where the electronic components have not been removed, the mounting density of the electronic components on the circuit board can be increased, and the electronic circuit device including the oscillation circuit can be downsized.

Further, according to the present invention, since the electronic components arranged under the outer case of the crystal oscillator for surface mounting are resistors formed by printing, the manufacturing is easy and the manufacturing cost can be reduced. In addition, the price of the product can be reduced.

Further, according to the present invention, since no electronic components constituting the oscillation circuit are arranged on the back side of the circuit board and the ground pattern is formed widely, it is hardly affected by external noise, and An electronic circuit device including an oscillation circuit with less frequency variation can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view schematically illustrating an example of an arrangement state of electronic components on a circuit board when an electronic circuit device including an oscillation circuit according to an embodiment of the present invention is applied to a temperature-compensated crystal oscillator.

FIG. 2 is a bottom view of a circuit board used in the temperature-compensated crystal oscillator (an electronic circuit device including an oscillation circuit) according to the embodiment of the present invention.

FIG. 3 is a schematic front view of a temperature-compensated crystal oscillator (an electronic circuit device including an oscillation circuit) according to the embodiment of the present invention.

[Description of Signs] 1 Circuit board 3 Crystal oscillator for surface mounting 4 Outer case 7 Backside circuit pattern 11 Ground pattern G Gap R1 to R4 Print resistor R5 Function trimming resistor

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masato Hirase 3158 Shimo-Okubo, Osawano-cho, Kamishinkawa-gun, Toyama F-term in Hokuriku Electric Industry Co., Ltd. 4E351 BB05 BB17 BB17 CC11 GG06

Claims (5)

[Claims] 1. A circuit board on which a front-side electrode pattern is formed on a front surface and a back-side circuit pattern including a ground pattern is formed on a back surface, and a surface mount mounted on the circuit board to form an oscillation circuit A plurality of electronic components including a crystal oscillator for use, wherein the crystal oscillator for surface mounting has a structure including an oscillation element inside an outer case, and the crystal oscillator for surface mounting has the outer case and An electronic circuit device including an oscillation circuit mounted on the surface so as to leave an interval between the surface and the surface of the circuit board, wherein the surface of the circuit board located under the outer case is provided. An electronic circuit device provided with an oscillation circuit, wherein at least one of the plurality of electronic components formed by printing is disposed in the region. 2. The electronic circuit device according to claim 1, wherein the plurality of electronic components are all mounted on the front side of the circuit board. 3. The electronic circuit device according to claim 1, wherein the at least one electronic component is a printed resistor. 4. A circuit board on which a front side electrode pattern is formed on a front side and a back side circuit pattern including a ground pattern is formed on a back side, and an oscillation circuit including a temperature compensation circuit is formed on the circuit board. A plurality of electronic components including a mounted surface-mount crystal oscillator, wherein the surface-mount crystal oscillator has a structure including an oscillation element inside an outer case, and the surface-mount crystal oscillator Is a temperature-compensated crystal oscillator mounted on the surface so as to leave an interval between the outer case and the surface of the circuit board, wherein the circuit board located below the outer case A temperature-compensated crystal oscillator, wherein a plurality of resistors formed by printing among the plurality of electronic components are arranged in the surface region. 5. The circuit board according to claim 4, wherein one or more functional trimming resistors formed by printing are arranged in a region outside the region on the surface of the circuit board.
A temperature-compensated crystal oscillator according to item 1.