JP3537643B2 - Electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component having a shield case.

[0002]

2. Description of the Related Art Conventionally, as electronic parts having a shield case, for example, a temperature-compensated crystal oscillator, a frequency selection device used in portable communication equipment, and the like are widely known.

For example, a temperature-compensated crystal oscillator, which is such an electronic component, includes a crystal resonator having an airtight container, a vibration section, a temperature compensation circuit mainly composed of a temperature-sensitive element, a resistor, and a capacitor, and an oscillation mainly composed of a transistor. A circuit, a frequency adjustment circuit mainly composed of a capacitor, is configured. For example, an electronic component 70 shown in FIG. 7 has electronic components 3 constituting the above-described circuits including a crystal oscillator mounted on a mounting board 71 made of ceramic, glass epoxy, or the like. Is covered by a shield case 72 made of a metal.

[0004] Such a shield case 72 has a housing shape with an open bottom, and at least the surface is made of a metal material that can be soldered. And shield case 7
A portion near the bottom opening of the second electrode 2 has a ground potential electrode pattern 73 and a solder 74 formed on the side surface and the surface periphery of the mounting board 71.
And the mounting board 71 and the shield case 7
2 were electrically and mechanically joined.

[0005]

In order to join such a shield case 72 to the mounting substrate 71, it is not necessary to form the ground potential electrode pattern 73 on the side surface and the surface periphery of the mounting substrate 71 as described above. However, the routing of the wiring pattern formed on the substrate is restricted, and the entire electronic component having the shield case 72 becomes large.
At the same time, when the shield case 72 is soldered, the molten solder 74 comes into contact with a wiring pattern other than the ground potential, causing an electrical short, destroying other electronic component elements 3 or a portion where the molten solder is unnecessary. For example, it spreads to the bottom side of the substrate, which may hinder the mounting of the electronic component on the printed wiring board, or may deviate the external dimensions of the finished product from the required dimensions.

Further, the shield case 72 is mounted on the mounting board 71.
In order to arrange at a predetermined position, a structure in which a part of the substrate 71 and a part of the shield case 72 are fitted to each other is provided,
It is necessary to be temporarily held, and processing of the mounting board 71 and processing of the shield case 72 are difficult and expensive.

Further, the shield case 72 and the mounting board 7
1 and the solder 74, the use of thread solder makes the joining operation complicated, and the use of cream solder or the like makes the electronic component element 3 mounted on the mounting board 71 difficult. The number of thermal histories increases, and the characteristics of the electronic component element 3 itself become unstable.

Further, the shield case 72 is mounted on the mounting board 7.
Since the minimum distance between the upper surface of the electronic component element 3 mounted on the device 1 and the ceiling surface of the shield case 72 is kept at 150 μm or more, the structure cannot sufficiently meet the demand for small size such as communication equipment. Was. This is because the proximity of the electronic component element 3 to the shield case 72 is the portion where the shield case 72 is connected to the ground potential (the shield case 72).
(Part of the periphery of the bottom opening) of the electronic component element 3 and the shield case 72 easily generate a stray capacitance component. In order to suppress the influence of the stray capacitance component, the minimum distance between the upper surface of the electronic component element 3 and the ceiling surface of the shield case 72 is kept at 150 μm or more.

The present invention has been devised in view of the above-mentioned problems, and has as its object to improve the joining structure of the shield case, greatly simplify the joining process of the shield case, and reduce the size and size of the shield case. An object of the present invention is to provide an electronic component that is reduced in weight.

[0010]

An electronic component according to the present invention is provided such that a part of a container of one electronic component element among a plurality of electronic component elements mounted on a substrate is covered with the electronic component element. In an electronic component formed by joining a shield case, the shield case is formed with a recessed portion to be joined to the container, and an energy beam is irradiated into the recessed portion to form a part of the recessed portion. A part of the container is melted and joined.

It is desirable that the cover of the electronic component element and the entire cover constituting the electronic component element be at the ground potential during operation on the circuit board. In addition, the above-described fusion bonding is performed in a state where the shield case and the electronic component element are in close contact with each other,
An energy beam, for example, a laser is radiated to the close portion in a spot manner to raise the temperature of the shield case to at least a high temperature at which the material of the shield case is melted.

[0012]

According to the present invention, the shield case is fusion-bonded to a part of the container of one electronic component element among the plurality of electronic component elements mounted on the substrate. That is, unlike the conventional case, it is not necessary to solder the shield case to the board, so that various problems caused by the soldering can be eliminated.

For example, structurally, there is no need to form an electrode pattern on the substrate to be joined to the shield case, so that the wiring pattern on the substrate can be routed more freely and the entire electronic component can be reduced in size.

Further, when the shield case is soldered, there is no short circuit with the wiring pattern due to the molten solder, so that the electronic component has high reliability. In addition, there is no trouble in mounting the electronic component on the printed wiring board, and the external dimensions are extremely stabilized.

Further, the difficult work by soldering is eliminated, the work of joining the shield case is facilitated, and the number of heat histories of the electronic component element is reduced, so that the characteristics are stabilized.

The structure of the shield case and the substrate is simplified,
Processing of the substrate and processing of the shield case are facilitated.

[0017] When the mounting height of the one electronic component element that is melt-bonded to the shield case among the electronic component elements mounted on the substrate is the highest, the one electronic component element and the shield case are not connected. Can be substantially eliminated, resulting in an electronic component having a very low height.

At the same time, even if the other electronic component element and the shield case are close to each other, if the container of this electronic component element is kept at the ground potential, the fused and joined portion becomes the portion connected to the ground potential. Therefore, the generation of the stray capacitance component between the other electronic component element and the shield case can be effectively suppressed, and the electronic component is stable in characteristics.

Further, in the present invention, the shield case is formed with a recessed portion to be joined to the container of one electronic component element, and the recessed portion is irradiated with an energy beam so that a part of the recessed portion is formed. The joining is performed by melting a part of the container.

As described above, since the fusion bonding portion of the shield case with the container is recessed, this recess portion becomes the lowermost portion of the ceiling surface of the shield case. Therefore, even if processing accuracy, thermal deformation and warpage occur on the ceiling surface of the shield case, the recessed portion can be reliably brought into contact with a part of the container. Then, by irradiating the recessed portion from the upper surface side of the shield case with an energy beam capable of melting and bonding the shield case and the container, reliable fusion bonding can be achieved.

Even when the height of the one electronic component element is lower than that of the other electronic component elements, the hollow portion of the shield case can be formed to forcibly fuse the electronic component element with the bonding electronic component element. . In any case, since the fusion bonding portion of the shield case with the container is concave, very stable fusion bonding can be performed.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electronic component according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is an external perspective view of an electronic component according to the present invention, and FIG. 2 is a sectional view thereof.

Here, the electronic component of the present invention means that a capacitor, a resistor transistor, an I
A component (module) on which an electronic component element such as a C element, a quartz oscillator, and a SAW filter is mounted to perform a predetermined operation.

In the following description, a temperature-compensated crystal oscillator will be described as an example of the electronic component. That is, the electronic component elements are a crystal oscillator, a capacitor, a resistor, a thermistor, and a transistor that constitute a temperature-compensated crystal oscillator.

In the drawing, reference numeral 10 denotes a temperature-compensated crystal oscillator (electronic component), 1 denotes a mounting substrate, 2 and 3 denote electronic component elements such as a crystal oscillator, a capacitor, a resistor, a thermistor, a transistor, and 4 denotes a shield. It is a case.

The mounting substrate 1 is formed on a substrate 11 such as a single-plate structure, a multilayer ceramic substrate having a predetermined wiring conductor formed therein, a glass epoxy substrate or the like, and at least a surface of the substrate 11 to constitute a predetermined circuit. Wiring pattern 12
And the wiring pattern 1 formed on the bottom and side surfaces of the substrate 11.
2 and a terminal electrode 13 connected to the terminal electrode 2.

The mounting board 1 is manufactured by a known method for manufacturing a multilayer wiring board, a thick film circuit board, or a glass epoxy board.

The electronic component elements 2 and 3 have a schematic circuit configuration of a temperature-compensated crystal oscillator, that is, various electronic component elements constituting a crystal oscillator section, a temperature compensation circuit section, a frequency adjustment circuit section, and an oscillation / amplification circuit section. It becomes. For example, in the case of a crystal unit, a metal hermetic container or a crystal unit in which a crystal vibrating piece is accommodated in an airtight container having a metal lid can be exemplified. , A thermistor, a capacitor in the frequency adjustment circuit section, a transistor in the oscillation / amplification circuit section,
Examples include a capacitor, a resistor, and an inductance element.

Among these electronic component elements, a particularly important electronic component element is the quartz oscillator 2 (one electronic component element) used by setting a part of the container to the ground potential. still,
Many of the other electronic component elements have their periphery protected and covered with an insulating material, and these are referred to as electronic component elements 3.

Here, the crystal unit 2 will be described. There are various types of airtight containers for the crystal unit 2. In the figure, a quartz oscillator having an SMD package which is surface-mounted on the mounting substrate 1 is used.

As shown in FIG. 3, the crystal resonator 2 has a housing shape in which a flat ceramic layer, a frame ceramic layer for mounting a crystal resonator element, and a frame ceramic layer for a crystal resonator element storage space are laminated from the bottom surface. Container 21, crystal vibrating piece 22, Fe-Ni
And a metal cover 23 made of an alloy (Kovar) or the like. That is, the housing 21 and the metal lid 23 constitute a container for hermetically sealing the quartz-crystal vibrating piece 22.

More specifically, an output electrode 24 to be soldered to the wiring pattern 12 of the mounting board 1 is formed on the bottom surface of the housing 21. A sealing conductor film (not shown) for seam welding the metal cover 23 and a weld metal ring 25 are arranged on the upper surface of the housing-like container 21. In consideration of the workability of performing seam welding between the metal lid 23 and the weld metal ring 25, the sealing conductor film and the weld metal ring 25 are connected to the ground potential. In addition, the sealing conductor film and the weld metal ring 25 have seam welding current contact electrodes (not shown) led out from the surface of the housing 21 to the side and bottom surfaces.

When the crystal resonator 2 is mounted on the mounting substrate 1, the seam welding current contact electrode derived from the sealing conductor film and the weld metal ring 25 is connected to the ground potential wiring pattern 12 of the mounting substrate 1. By soldering, the metal lid 23 is at the ground potential.

Although not shown in the figure, there is also a quartz oscillator in which a disc-shaped or strip-shaped quartz-crystal vibrating piece is housed in a container formed of a circular or square stem, a circular or square metal cap, In this case, when mounted on the mounting board 1, the seam welding current contact electrode derived from the sealing conductor film and the weld metal ring 25 is connected to the wiring pattern 1 of the ground potential of the mounting board 1.
By electrically connecting the metal cap 2 to the metal cap, the metal lid 23 is set to the ground potential.

Here, comparing the heights of the electronic component elements mounted on the mounting substrate 1, the electronic component elements 3 such as resistors, capacitors, and transistors are about 0.9 mm, and the height of the crystal resonator 2 is about 0.9 mm. The height is slightly higher, about 1.0 mm.

The shield case 4 has a shape that covers at least the electronic component elements 2 and 3, for example, has a housing shape opened from the bottom side, and is formed by press-molding SUS304. That is, the shield case 4 is
, And has a thickness of about 80 μm. Also, the four side surfaces 42
Are slightly shorter than the mounting height of the crystal unit 2.

The thickness of 80 μm corresponds to, for example, a reduction in weight and size of a mobile communication device incorporating electronic components. For example, a shield case of about 150 μm has conventionally been used. In addition, the thinness of 80 μm prevents instantaneous diffusion of heat during fusion bonding between the shield case 4 and the crystal unit 2, which will be described later, and reduces the heat capacity. This is because the temperature can be raised to at least about 1250 ° C. to 1300 ° C. at which SUS 304, which is the material of the shield case 4, is melted.

The surface of the shield case 4 is plated with Ni in a plating tank having a black pigment such as carbon (C), and only the surface is blackened. This blackening of the surface is performed for the following two points.

One is that when the shield case 4 is irradiated with an energy beam such as a laser as described above, the reflection of light on the surface of the shield case 4 is suppressed, the energy beam is efficiently absorbed, and This is to achieve energy saving of the energy beam power. For example,
In the case of the silver-white shield case 4, a current of 13 A must be supplied to the energy beam lamp, while in the case of the black shield case 4, the energy beam lamp is supplied with the current of 11 A under the same conditions. Stable fusion bonding can be achieved.

Another reason is that when a mark indicating a model number or a characteristic is formed on the surface of the shield case 4 by scribing with an energy beam, the mark (mark) is clearly displayed. That is, conventionally, the mark was printed and cured with a black resin paste on a silver-white case, and the contrast was inferior. In the present invention, however, the contrast was improved by scribing the energy beam, and Fine marks can be formed. The intensity of the energy beam at the time of forming the mark may be such that the black Ni plating layer on the surface can be burned off.

Next, the above-mentioned mounting substrate 1, crystal oscillator 2,
A method of assembling the temperature-compensated crystal oscillator 10 using the electronic component element 3 and the shield case 4 and a joining structure of the shield case 4 will be described.

First, a quartz oscillator 2 is mounted on a mounting substrate 1 on which a wiring pattern 12 is formed by a known method of manufacturing a thick film circuit board.
A cream solder is applied to mount the electronic component element 3 on the wiring pattern 12.

Next, in the portion where the cream solder is applied,
The crystal unit 2 and the electronic component element 3 are mounted and joined by reflow processing. Here, it is desirable that the crystal unit 2 be disposed near the center of the mounting substrate 1. As a result, the crystal resonator 2 is mounted on the mounting substrate 1 with its upper surface protruding as compared with the other electronic component elements 3.

Next, the crystal oscillator 2 and other electronic component elements 3
So that the crystal case 2 and other electronic component elements 3 are covered from the upper surface of the mounting substrate 1 so that the shield case 4
Is placed. In this state, the ceiling surface 4 of the shield case 4
1 is held in a state of being placed on the upper surface of the crystal resonator 2, that is, the metal lid 23.

Next, an energy beam such as a YAG laser is spot-irradiated onto a predetermined surface of the shield case 4, that is, a region in contact with the upper surface of the crystal unit 2. And the metal lid 23 of the crystal unit 2 are melt-bonded. This fused portion is indicated by X.

This is because when the shield case 4 is locally irradiated with an energy beam by the energy beam, the temperature of the shield case 4 is locally increased. For example, when the temperature of the shield case 4 becomes about 1250 ° C. or more, which is the melting temperature of SUS304, 4
Is melted, and as a result, the quartz oscillator 2 is melt-bonded to the metal lid 23 made of the Fe—Ni alloy.

As a result, the shield case 4 can be firmly melt-bonded to the upper surface of the crystal unit 2 to cover the crystal unit 2 and the electronic component 3 mounted on the mounting substrate 1. In addition, as described above, since the metal lid 23 of the crystal unit 2 to which the shield case 4 is joined is at the ground potential, the entire shield case 4 is at the ground potential, and a shielding effect can be provided.

The above-described mark forming process using an energy beam such as a laser is performed before or after the fusion bonding process. The energy beam at this time may have such an intensity that the black Ni plating on the surface of the shield case 4 is scattered.

As described above, in the temperature-compensated crystal oscillator 10, the shielding case 4 is structurally
The thickness is reduced from 0 μm to about 80 μm. Moreover, the crystal resonator 2 having the highest mounting height on the mounting substrate 1 and the shield case 4 are in close contact with each other. Furthermore, since the joining of the shield case 4 is not performed between the shield case 4 and the mounting board 1 via solder unlike the related art, the thickness corresponding to the joining solder of the shield case 4 can be reduced. .

From the above points, the temperature-compensated crystal oscillator 10
Can be made very thin, and it becomes possible to cope with a reduction in size and weight of, for example, a mobile communication device on which the temperature-compensated crystal oscillator 10 is mounted. For example,
While the height of the electronic component 70 shown in FIG. 7 is about 2 mm, the height of the temperature-compensated crystal oscillator 10 of the present invention can be reduced to about 1.6 mm, which is about 20%.

The bonding structure is fusion bonding between the ceiling surface 41 of the shield case 4 and the metal cover 23 of the crystal unit 2, and is not a conventional solder bonding. Therefore,
Unlike the related art, there is no need to form a wiring pattern of the ground potential for soldering the shield case 72 around the mounting board 71 shown in FIG. improves. Further, no short-circuit occurs with the predetermined signal wiring pattern caused by melting of the solder for joining the conventional shield case 72, and the temperature-compensated crystal oscillator 10 with high operation reliability is obtained.
It becomes. Further, a structure for temporarily holding both the shield case 4 and the mounting board 1 is not required.

From the above points, the temperature-compensated crystal oscillator 10
The whole is greatly simplified, the external dimensions are very stable and the size is reduced.

Further, as the joining operation, there is no need to perform a thread soldering operation, which requires a manual operation.
Crystal resonator 2 and electronic component element 3 mounted on mounting substrate 1
, The number of heat treatments is reduced, and the characteristics of itself are stabilized.

The shielding action of the shield case 4 is as follows.
Since the shield case 4 is grounded in the vicinity of the center of the ceiling surface 41, even if the space between the electronic component element 2 and the shield case 4 is narrower than the conventional electronic component 70. On the contrary, since the generation of the stray capacitance component can be effectively suppressed, the predetermined operation of the temperature-compensated crystal oscillator 10 is stabilized.

In the above-described structure, the ceiling surface 41 of the shield case 4 is substantially flat, and the flat surface portion is fusion-bonded to the metal cover 23 at the ground potential of the crystal unit 2. On the other hand, as shown in FIG. 4, through holes 43 are formed at a plurality of places on a predetermined surface of the shield case 4, that is, in a region in contact with the upper surface of the crystal unit 2, and the through holes 43 are formed. Alternatively, the ceiling surface 41 of the shield case 4 and the metal lid 23 of the crystal unit 2 may be melt-bonded by irradiating an energy beam such as a laser in a spot manner.

With such a structure, the position to be irradiated with an energy beam such as a laser can be easily and reliably found, and the fused joint portion X can be visually confirmed. Energy intensity can be reduced.

As shown in FIG. 5, a predetermined surface of the shield case 4, that is, a region in contact with the upper surface of the crystal unit 2, has a diameter of 20 to 100 μm, for example.
A recess 44 having a thickness of about 20 μm or more is formed, and an energy beam such as a laser is radiated to this recess 44 in a spot-like manner, so that the ceiling surface 41 of the shield case 4 and the metal lid 23 of the crystal unit 2 are separated. It may be melt-bonded.

It is desirable to irradiate an energy beam such as a laser beam to a plurality of locations for simultaneous fusion bonding. However, it is necessary to sequentially irradiate a plurality of locations for fusion bonding due to limitations of equipment and the like. Here, at the time of the fusion bonding performed at the first location, the raised heat may cause undulation in the shield case 4 at about 20 μm. Apparently, even if the ceiling surface 41 of the shield case 4 is flat, the melt-bonded portion X at the second location is
In some cases, the ceiling surface 41 of the shield case 4 does not contact the metal cover 23 of the crystal unit 2, and the ceiling surface 41 of the shield case 4 and the crystal unit 2 also depend on the processing accuracy of the shield case 4. In some cases, the metal lid 23 is not in contact.

In such a case, for example, in the area where the shield case 4 is in contact with the metal lid 23 of the crystal unit 2,
By forming the recessed portion 44 of 0 μm or more, the portion to be welded can be stably brought into contact with the shield case 4 and the metal lid 23 of the crystal unit 2, thereby improving the reliability of the welded joint. I do.

FIG. 6 shows a depressed portion 45 formed in a predetermined surface of the shield case 4, that is, in a region in contact with the upper surface of the crystal unit 2, in an area in contact with the upper surface of the crystal unit 2. And a plurality of joints X
May be formed.

That is, the crystal oscillator 2 mounted on the mounting substrate 1 and the plurality of electronic component elements 3 are not necessarily the highest in the mounting height of the crystal oscillator 2. In such a case,
A recess 45 recessed in the ceiling surface 41 of the shield case 4
Is formed to avoid contact between the other electronic component element 3 having the highest mounting height and the shield case 4 so that the shield case 4 and the metal cover 23 of the crystal unit 2 come into contact with each other. I have.

For example, in the temperature-compensated crystal oscillator 10, when a trimmer capacitor is used for the frequency adjustment circuit, the height of the trimmer capacitor that is the electronic component element 3 is higher than that of the crystal resonator that is the crystal resonator 2. May be higher.

In this case, an opening may be formed in a portion of the shield case 4 which can come into contact with the trimmer capacitor so that only the upper portion (the head portion of the adjustment pin) of the trimmer capacitor protrudes. By doing so, the shield case 4 can be stably welded to the crystal unit 2 and
The capacitance of the trimmer capacitor can be easily adjusted even after the shield case 4 is joined.

In the above-mentioned embodiment, the temperature-compensated crystal oscillator 10 and the crystal oscillator 2 are shown as the electronic components.
This is an example in which a crystal resonator 2 having (a part of a container) is used.

However, when temperature compensation of the crystal oscillator is performed based on the digital compensation data as in a digital type temperature compensated crystal oscillator, the memory means and the memory element for storing the digital compensation data are controlled. Control means is required. When the means that can be integrated into such an IC uses a semiconductor element sealed with a ground potential metal lid, the crystal unit 2 may be sealed with a ground potential metal lid as necessary. It may be used as a semiconductor element.

From the above-described examples and the like, it can be seen that the quartz resonator 2 may be any electronic component element having a metal cover at the ground potential.

Accordingly, the electronic component element body is mounted on the metal stem and sealed with a metal container, and the electronic component element, for example, the surface elasticity of the crystal resonator or the piezoelectric single crystal substrate is formed using a disk-shaped crystal resonator element. An electronic component element (SAW device) that operates using waves may be used as a bonding electronic component element.

For example, a SAW device is used in a mobile communication device for a circuit in a very high frequency region such as a local oscillation circuit and a communication channel selection circuit. Therefore, the electronic component of the present invention can be widely applied to components other than the temperature-compensated crystal oscillator, such as the local oscillation circuit portion and the communication channel selection circuit portion as one electronic component.

[0070]

As described above, according to the present invention, one electronic component element mounted on a mounting substrate is provided as a bonding structure of a shield case for covering the electronic component element mounted on the mounting substrate, instead of being bonded and fixed to the mounting substrate. Since the shield case is joined with an energy beam, the joining process of the shield case is greatly simplified, and the size and weight can be reduced, and an electronic component that is stable in operation can be provided. Further, since the shield case has a concave portion at which the one electronic component element is joined to the container, an electronic component capable of performing very stable fusion bonding can be provided.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a temperature-compensated crystal oscillator which is an example of an electronic component of the present invention.

FIG. 2 is a cross-sectional view of a temperature-compensated crystal oscillator which is an example of the electronic component of the present invention.

FIG. 3 is a cross-sectional view showing a structure of a bonding electronic component element used in a temperature-compensated crystal oscillator which is an example of the electronic component of the present invention.

FIG. 4 is a partial sectional view of a shield case joining structure portion of another electronic component of the present invention.

FIG. 5 is a partial sectional view of a shield case joining structure portion of another electronic component of the present invention.

FIG. 6 is a partial cross-sectional view of a shield case joining structure portion of still another electronic component of the present invention.

FIG. 7 is a cross-sectional view of a temperature-compensated crystal oscillator that is an example of a conventional electronic component.

[Explanation of symbols]

1 ... Mounting board 2 .... Electronic components for bonding 23 ... Metal cover with earth potential 3 ... Electronic component elements 4 .... Shield case 41 ・ ・ ・ Ceiling surface 44, 45 ... hollow

Claims (1)

(57) [Claims] A plurality of electronic component elements mounted on a substrate;
Of these, one part of the electronic component element
Composed of a shield case to cover the element
In the electronic component, the shield case is provided with a concave recess to be joined to the container.
Energy beam within the recess.
By irradiating a part of the recess and the container
Electronic part characterized in that a part of it is melted and joined
Goods.