JP2003078280A - Electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and lightweight electronic component operating stably by improving the bonding structure of a shield case thereby reducing the bonding process of the shield case. SOLUTION: The electronic component comprises a container body having a cavity opening upward with a sealing conductor being fixed around the cavity opening, an electronic component element being contained in the container body, a substrate for mounting the container body and circuit components, and a shield case being mounted on the sealing conductor of the container body to seal the cavity opening and to cover the upper part of the circuit components.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting a crystal unit comprising a container and a capacitor which is a circuit component on a substrate, and a method for mounting the container on the substrate. The present invention relates to an electronic component in which the upper part of a circuit component is covered by a shield case. 2. Description of the Related Art Conventionally, as an electronic component having a shield case, for example, a temperature-compensated crystal oscillator used for portable communication equipment has been widely known. [0003] Such a temperature-compensated crystal oscillator, which is an electronic component, includes a vibrating section composed of a crystal oscillator having an airtight container, a temperature compensation circuit composed of a temperature-sensitive element, a resistor and a capacitor, and an oscillation circuit composed of a transistor. , And a frequency adjustment circuit composed of a capacitor. For example, a temperature-compensated crystal oscillator 51, which is an electronic component shown in FIGS. 8 and 9, includes a crystal oscillator 53 and each circuit of the above-described temperature-compensated crystal oscillator on a substrate 2 made of ceramic or glass epoxy. The circuit components 8 to be configured are mounted. Further, the metal lid 5 of the crystal oscillator 53
6, a shield case 57 is connected by welding or the like, and the shield case 57 is arranged so as to cover substantially the entire area of the substrate 2. [0005] Such a shield case 57 is formed in a housing shape or a flat plate shape so as to cover at least the electronic component 8 including the crystal oscillator 53, and is formed, for example, by pressing SUS304. Further, by disposing the shield case 57 on the metal lid 56 of the electronic component 53 and irradiating an energy beam such as a laser to raise the temperature of the shield case 57 to about 1250 ° C. to 1300 ° C. and melt it, The shield case 57 and the metal lid 56 are electrically and mechanically joined. [0006] When such a shield case 57 is to be joined to the crystal oscillator 53, not only is the crystal oscillator 53 and a plurality of electronic components 8 mounted on the substrate 52, but also all others. Finally, the shield case 57 is mounted on the metal cover 56 of the crystal oscillator 53.
A fusion bonding step of electrically and mechanically bonding the shield case 57 and the metal lid 56 by irradiating an energy beam such as a laser on the shield case 57 has been performed. On the other hand, in recent years, with the demand for miniaturization of electronic components, reduction in height and area of electronic components has been studied. The lid 56 has been reduced in thickness so as to maintain its functions. However, when the shield case 57 is joined to the crystal oscillator 53, it is difficult to adjust the intensity of the energy beam applied to the metal cover 56 of the crystal oscillator 53. If the energy beam is too strong, the metal cover The body 56 is also melted inside the crystal oscillator 53, and the melted metal melt scatters on the surface of the crystal oscillator 54 to contaminate the surface, impairing the oscillation characteristics of the crystal oscillator 53,
Eventually, the electrical characteristics of the electronic component 51 may be impaired. In particular, the shield case 57 and the metal lid 5
The problem that the molten metal is scattered from the metal lid 56 when the thickness of the metal layer 6 is thin has been prominent. In order to prevent the metal lid 56 of the crystal oscillator 53 from being melted inside, it is also important to increase the thickness of the metal lid 56, which is at least about 100 μm. It is necessary to make the shield case 57 thick enough.
When the electronic component 51 is bonded to the upper surface of the metal lid 56, the thickness of the electronic component 51 as a finished product cannot be reduced, and the weight increases. Further, since the shield case 57 is further joined to the upper surface of the metal cover 56 of the crystal oscillator 53, a sufficient shielding effect can be obtained depending on the connection state of the shield case 57 and the metal cover 56. There was another problem. On the other hand, the shield case 57 and the metal lid 5
When the joint 6 is melt-bonded, a laser beam is irradiated from the upper surface side of the shield case 57. Since the shield case has a flat plate shape, a special positioning mechanism or the like is required to irradiate a laser spot to an appropriate position. It had to be used, and the manufacturing process was complicated. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to form an electronic component with a low profile and to melt a metal melt by fusion bonding at the time of manufacture. It is an object of the present invention to provide an electronic component which can surely obtain a shielding effect without impairing the characteristics of the electronic component and which is reduced in size and weight. According to the present invention, there is provided a container having a cavity with an open upper portion, a sealing conductor attached around the cavity opening, and a container housed in the container. An electronic component element, the container, a substrate on which a circuit component is mounted, and a shield case mounted on a sealing conductor of the container to seal the cavity opening and cover an upper portion of the circuit component And an electronic component having: According to the structure of the present invention, the shield case is disposed so as to cover substantially the entire area of the upper part of the substrate.
At the same time, the sealing conductor formed around the upper opening of the container mounted on the substrate is directly melt-bonded to the shield case to hermetically seal the container opening. That is, unlike the conventional case, it is not necessary to separately join the shield case to the metal lid body that hermetically seals the upper surface of the container body by welding or the like. Also, there is no scattering of the molten metal from the metal lid. In addition, since the shield case is directly melt-bonded to the sealing conductor, if a metal lid is used, the thickness of the shield case is made sufficiently thick so as not to be melted by bonding with a laser beam. As long as there is no restriction on the necessity of such a case, sufficient fusion bonding can be performed and the function of the shield case is not impaired, it is possible to make the shield case even thinner. Will be possible. Conventionally, there is a step of hermetically sealing with a metal lid when manufacturing a quartz oscillator.
When manufacturing an electronic component, a step of joining the shield case to the upper part of the metal lid was necessary. However, the present invention simplifies the step of joining the shield case, which was performed separately. 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 of the present invention, FIG. 2 is a sectional view thereof, and FIG. 3 is a sectional view of a main part thereof. In the figure, 1 is a temperature-compensated crystal oscillator (electronic component), 2 is a substrate, 3 is a crystal oscillator, 4 is a container housing a crystal oscillator, 7 is a shield case, 8
Are circuit components such as capacitors, resistors, thermistors, and transistors. Here, the circuit component 8 of the present invention
Denotes components such as a capacitor, a resistor, a transistor, an IC element, a SAW oscillator and a SAW filter mounted on the upper surface of the substrate 2. The electronic component element is an element that can be accommodated in the container 4. For example, if the element is a temperature-compensated crystal oscillator, the electronic component element is a crystal oscillator constituting the crystal oscillator. . The substrate 2 is a single-plate structure, a multi-layered ceramic substrate having a predetermined wiring conductor formed therein, a substrate 21 such as a glass epoxy substrate, and a wiring formed at least on the surface of the substrate 21 and constituting a predetermined circuit. It is composed of a pattern 22 and terminal electrodes 23 formed on the bottom and side surfaces of the base 21 and connected to the wiring pattern 22. Such a substrate 2 is produced by a known method for manufacturing a multilayer wiring substrate, a thick film substrate, or a glass epoxy substrate. Here, the crystal oscillator 3 will be described.
There are various types of the container 4 of the crystal oscillator 3. In the figure, an SMD package that is surface-mounted on the substrate 2 is used. As shown in FIG. 3, the crystal oscillator 3 has a flat ceramic layer 41 from the bottom, a frame-shaped ceramic layer 42 on which the crystal oscillator 5 is mounted, and a frame-like shape having a cavity for accommodating the crystal oscillator 5. It comprises a container body 4 on which a ceramic layer 43 is laminated, a quartz oscillator 5, and a shield case 7 made of an Fe—Ni alloy (Kovar) or the like. That is, the crystal unit 5 is hermetically sealed by the container 4 and the shield case 7. An external electrode terminal 46 is formed on the bottom surface of the container 4 to be soldered to the wiring pattern 22 of the substrate 2. Around the opening of the container 4, a frame-shaped sealing conductor 44 for seam welding the shield case 7 is provided with an A.
g are joined and arranged by a brazing filler metal or the like. The sealing conductor 44 has a conductive film adhered to its joint surface.
The conductor film and the sealing conductor 44 are set to the ground potential in consideration of the workability of performing seam welding between the shield case 7 and the sealing conductor 44. The sealing conductor film and the sealing conductor 44 have seam welding current contact electrodes led out from the surface of the container 4 to the side surface and the bottom surface. As described above, in the present invention, the shield case 7 also functions as a conventional metal lid at the same time, and the shield case 7 of the crystal oscillator 3 is a metal lid. Although not shown in the figure, when mounted on the substrate 2, the seam welding current contact electrode derived from the sealing conductor film and the sealing conductor 44 is connected to the ground potential wiring pattern of the substrate 2. Welding becomes possible by electrically connecting the shield case 7 to the shield case 7. Here, the container body 4 mounted on the substrate 2,
Comparing the heights of the circuit components 8, the electronic component elements 8 such as resistors, capacitors, and transistors are 0.9 mm
And the height of the crystal oscillator 3 is slightly higher at about 1.0 mm. The shield case 7 may be formed so as to cover at least the upper part of the crystal oscillator 3 and the circuit component 8, for example, a rectangular flat plate having a size corresponding to at least the substrate 2. 4 shield case 7
1) More preferably, it is sufficient if the housing is open from the bottom side of the flat plate (shield case 7 in FIG. 2).
With such a configuration, a more sufficient shielding effect can be obtained. Further, such a shield case 4 is made of SU
It is formed by pressing S304. That is, when the shield case 4 is formed in a housing shape having an open bottom surface,
It has a ceiling surface and four side surfaces, and its thickness is about 80 μm to 100 μm. The height dimension of the side surface is slightly shorter than the mounting height of the crystal oscillator 3. Next, a description will be given of a method of assembling the crystal resonator 5 and the temperature-compensated crystal oscillator using the substrate 2, the crystal oscillator 3, the circuit component 8, the shield case 7, and the bonding structure of the shield case 7. First, a method of assembling the crystal unit 5 will be described.
The conductive adhesive member 45 is cured by an electrode pad (not shown) formed on the upper surface of the step portion in the cavity of the container body 4.
A conductive resin paste is applied, and the crystal oscillator 5 is placed on top of the conductive resin paste.
With. Thereafter, the conductive resin paste is cured by heating, and the connection and fixation of the crystal unit 5 and the container 4 are performed. Further, the shield case 7 is placed so as to cover the upper part of the opening of the crystal oscillator 3, and the roller is scanned at a position corresponding to the upper part of the sealing conductor 44 of the crystal oscillator 3, a predetermined current is passed, and the shield case 7 is The sealing conductor 44 is fusion-bonded by seam welding. Note that beam welding may be used. Next, a method of assembling a temperature-compensated crystal oscillator will be described.
A cream solder is applied on the wiring pattern 22 on which the crystal oscillator 3 and the circuit component 8 are mounted. Thereafter, the circuit components 8 other than the predetermined crystal oscillator 3 are all mounted at predetermined positions on the substrate 2 on the portion where the cream solder is applied, and finally, the crystal oscillator 3 is mounted on the substrate 2 at a predetermined position. At this position, the external extension of the shield case 7 is placed from above to cover the other circuit components 8, and the crystal oscillator 31 is bonded onto the substrate 2 by reflow processing. Here, the crystal oscillator 3 may be arranged near the center of the substrate 2 or may be arranged closer to one end face. At this time, since the height of the ceramic package 4 of the crystal oscillator 3 on the substrate 2 is often higher than the other circuit components 8, the shield case 7 includes the temperature-compensated crystal oscillator 1 Will be arranged so as to cover the upper part of the whole as a whole. In view of the above, as a joining structure, the ceiling surface 70 of the shield case 7 is arranged above the cavity opening like a metal lid of the crystal oscillator 3 and is hermetically joined by welding. Therefore, the step of mounting the shield case 7 at the time of manufacturing the temperature-compensated crystal oscillator 1 becomes unnecessary, so that the manufacture of the temperature-compensated crystal oscillator 1 can be facilitated. Also, since the shield case 7 also functions as a lid of the crystal oscillator 3 and does not need to be separately joined to the metal lid of the crystal oscillator 3, the shield case 7 and the conventional metal lid Problems that occurred due to circumstances, for example,
If the intensity of the irradiated energy beam is not adjusted properly, the melted portion on the lower surface of the metal lid corresponding to the welded portion of the shield case 7 scatters and contacts the surface of the crystal resonator inside the cavity, Polluting the transducer,
In some cases, the electrical characteristics of the crystal unit and, in turn, the electrical characteristics of the temperature-compensated crystal oscillator may be degraded, but there is no danger of such abnormalities occurring. Further, conventionally, the shield case 7 and the metal cover of the crystal unit have been joined by irradiating an energy beam. However, the shield case and the metal cover can be substantially integrated, and the temperature compensation can be performed. The thickness of the crystal oscillator 1 can also be reduced. As described above, since the joining is not performed by the energy beam, the shield case 7
The thickness of the metal cover (i.e., the metal lid) may be a minimum thickness that can withstand seam welding, for example, 0.5 mm to 0.8 m.
Even if it is about m, it can be manufactured sufficiently. As described above, it is possible to further reduce the thickness. From the above points, the entire electronic component is greatly simplified, the external dimensions are extremely stabilized, and the size is reduced. Further, of the crystal oscillator 3 and the circuit components 8 mounted on the substrate 2, the crystal oscillator 3 is not necessarily the electronic component element having the highest mounting height. In such a case, as shown in FIG. 5, a one-step recessed portion 72 is formed in the ceiling surface of the shield case 71, and the other electronic component element 3 having the highest mounting height and the shield case 7 are connected. By avoiding contact, the shield case 7 hermetically seals the upper surface of the cavity of the crystal oscillator 3 like a metal lid. The depression 72 is formed to have a diameter of, for example, about 20 to 100 μm and a thickness of 20 μm or more. Further, in this case, in order to hermetically seal the upper portion of the cavity opening of the ceramic package 4 in the recess 72, welding and joining by an electron beam other than seam welding are also effective. For example, in the above-described example, when a trimmer capacitor is used for the frequency adjustment circuit in the temperature compensated crystal oscillator, the trimmer capacitor as the electronic component element 8 is connected to the crystal oscillator 3, that is, the flat portion of the shield case 72. An example is a case where the mounting height is higher than the lower surface height. In this case, an opening may be formed in a portion of the shield case 72 which can come into contact with the trimmer capacitor so that only the upper part (the head portion of the adjustment pin) of the trimmer capacitor protrudes. By doing so, the shield case 72 can be stably welded to the crystal oscillator 3 and the capacitance of the trimmer capacitor can be easily adjusted even after the shield case 72 has been joined.
In the above-described example, a trimmer capacitor is illustrated. However, when a protruding component is mounted on the substrate 2, a similar method is performed to cover the upper surfaces of the crystal unit 3 and the circuit component 8. The case 72 can be placed without any problem. As a fourth embodiment, as shown in FIG. 6, the portion of the shield case 73 mounted on the upper portion of the sealing conductor 44 of the crystal oscillator 3 is substantially fitted with the sealing conductor 44. A recess 731 is formed. The sealing conductor 44 of the crystal oscillator 3 having an open top is mounted so as to be fitted to the recessed portion 731, and a laser beam is irradiated from the shield case 73 side by seam welding or the like to seal the shield case 73. The conductor for use 44 can also be joined. This makes it easier to mount the shield case 73 on the sealing conductor 44 of the crystal oscillator 3 and facilitates manufacturing. Moreover, the recess 73 of the shield case 73
In (1), by melting and joining the periphery of the inclined portion on the upper surface side, it is possible to prevent the metal melt from scattering into the inside of the crystal unit 4, thereby preventing the oscillation characteristics from being impaired. Further, as a fifth embodiment, a portion of the shield case 74 mounted above the opening of the crystal oscillator 3 is formed so as to be fitted inside the sealing conductor 44 in the opening of the crystal oscillator 3. A portion may be formed, and the shield case 74 and the sealing conductor 44 may be joined by seam welding or the like. By forming the shield case 74 in this manner, the manufacturing is facilitated in the same manner as described above, and even when the surface of the shield case 74 is irradiated with a laser beam by seam welding, the projection 741 forms the sealing conductor 44. Since the opening enters the inside of the crystal oscillator 3, it is possible to prevent the oscillation characteristics from being impaired due to melting and the metal melt scattered inside the cavity and attaching to the surface of the crystal resonator 5. In the above embodiment, a temperature-compensated crystal oscillator is used as the electronic component 1 and the crystal oscillator 3 is
Shield case 7 which is ground potential on the upper surface for SMD
Was used. However, when temperature compensation of the temperature of the crystal unit is performed based on digital compensation data as in a digital temperature compensation crystal oscillator, a memory means for storing digital compensation data and a memory element are controlled. Control means is required. When the means that can be integrated into such an IC uses a semiconductor element sealed with a metal cover at the earth potential, the crystal oscillator 3 is sealed with a metal cover at the earth potential as necessary. It may be used as a semiconductor element. From the above-described examples and the like, it can be seen that the crystal oscillator 3 may be any electronic component element having a metal lid at a ground potential. Therefore, the electronic component element body is mounted on the metal stem and sealed with a metal container, and the surface of an electronic component element, for example, a crystal resonator using a disk-shaped crystal resonator or the surface of a piezoelectric single crystal substrate An electronic component element (SAW device) that operates using elastic waves may be used in place of the crystal resonator of the present invention. 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 portion and a communication channel selection circuit portion. 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. As described above, according to the present invention, the shield case is directly joined to the sealing conductor in the opening of the electronic component as a joining structure of the shield case covering the electronic component mounted on the substrate. It is fixed. Conventionally, a shield case is separately bonded to the upper surface of the metal lid by an energy beam, and the molten metal lid scatters due to the intensity of the energy beam to the surface of the crystal unit, and the electric power of the crystal unit is reduced. Although the characteristics were sometimes impaired, the step of joining the shield case to the metal lid was not required, and the electric characteristics of the crystal resonator were not impaired as described above. Further, the connection between the crystal unit and the shield case has become more reliable, and the shielding effect can be obtained more reliably. As described above, it has become possible to provide an electronic component which is reduced in size and weight and which is also stable in operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an external perspective view of a temperature-compensated crystal oscillator which is an electronic component of the present invention. FIG. 2 is a cross-sectional view of a temperature-compensated crystal oscillator that is an electronic component of the present invention. FIG. 3 is a cross-sectional view of a main part showing a structure of a crystal resonator used for a temperature-compensated crystal oscillator which is an electronic component of the present invention. FIG. 4 is a sectional view of a temperature-compensated crystal oscillator as an electronic component according to a second embodiment of the present invention. FIG. 5 is a cross-sectional view of a temperature-compensated crystal oscillator as an electronic component according to a third embodiment of the present invention. FIG. 6 is a sectional view of a fourth embodiment of a temperature-compensated crystal oscillator which is an electronic component of the present invention. FIG. 7 is a sectional view of a fifth embodiment of a temperature-compensated crystal oscillator which is an electronic component of the present invention. FIG. 8 is a cross-sectional view of a temperature-compensated crystal oscillator that is a conventional electronic component. FIG. 9 is a cross-sectional view illustrating a structure of a crystal resonator used in a temperature-compensated crystal oscillator, which is a conventional electronic component. It is the principal part sectional view of the mounting state of the crystal oscillator of the conventional crystal oscillator, and its enlarged view. [Description of Signs] 1 ... Temperature-compensated crystal oscillator 2 ... Substrate 21 ... Base 22 ... Wiring pattern 23 ... Terminal electrode 25 ... Seal ring 26 ... External terminal electrode 3 ... Crystal oscillator 4 ... Container 5 ... Crystal vibrator 7 ... Shield case

Claims (1)

Claims: 1. A container body having a cavity with an open top and a sealing conductor attached around the cavity opening, and an electronic component element housed in the container body. The container body;
An electronic device comprising: a substrate on which a circuit component is mounted; and a shield case that is mounted on a sealing conductor of the container body to seal the cavity opening and cover an upper portion of the circuit component. parts.