JP2003198320A - Package for acoustic surface wave filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of a conventional package such as that the LC resonance with the capacitance components that an acoustic surface wave filter element and the package have occurs, which incurs the deterioration of the isolation property between signal lines, since it is of such structure that the two or more grounding electrodes of the acoustic surface wave filter element are connected with each other via inductance components. <P>SOLUTION: It is possible to remove the electric conductivity of the ground conductor within the package, and eliminate the inductance components since at least two grounding conductor layers 12 are arranged within an insulating substrate 11. At least the two grounding electrodes of the elastic surface wave filter element 17 are severally connected to the ground conductor, and besides are electrically connected severally to the grounding conductors of an external electric circuit. The LC resonance with the capacitance components that the acoustic surface wave filter element 17 and the package have can be suppressed, and it becomes possible to improve the quantity of attenuation in a checking area turned into high frequency and the deterioration of the isolation between input and output distributing wires 13 and 13. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave filter package used to house a surface acoustic wave filter mounted on a mobile communication device or the like. It is. 2. Description of the Related Art Conventionally, a large number of electronic devices are incorporated in electronic devices such as mobile communication devices such as mobile phones. In recent years, communication devices such as mobile phones have been rapidly miniaturized, and each electronic device mounted thereon has also been required to be miniaturized. At the same time, electronic component storage packages used in the electronic devices have been miniaturized. Multifunctionalization has been required. [0003] For example, a surface acoustic wave (surface acoustic wave element) filter used in a cellular phone generally has a ground conductor layer 2 inside and a surface acoustic wave on the top side as shown in a sectional view of FIG. A substantially rectangular insulating substrate 1 made of an electrically insulating material such as an aluminum oxide sintered body having a concave portion 1a in which the filter element 7 is mounted and accommodated, and a lid attached to the upper surface side of the insulating substrate 1 to close the concave portion 1a A surface acoustic wave filter package comprising a body 5 is prepared, and a surface acoustic wave filter element 7 having at least two or more ground electrodes is accommodated in a concave portion 1a provided in an insulating base 1 of the surface acoustic wave filter package. At the same time, the input / output electrodes of the surface acoustic wave filter element 7 are connected to predetermined input / output wirings 3 made of a metallized wiring layer via bonding wires 6. 5 is joined to the frame-shaped metallized layer 4 via a sealing material (not shown) such as glass, resin, brazing material or the like, and a surface acoustic wave filter element 7 is placed inside a container comprising the insulating base 1 and the lid 5. It is manufactured by housing airtightly. This surface acoustic wave device is used in a portable telephone as a surface acoustic wave device having a pass band center frequency from 800 MHz to several GHz. A required characteristic at that time is suppression of signals outside the pass band. On the other hand, the characteristics outside the pass band are improved by optimizing the electrode finger pattern of the surface acoustic wave filter element 7, but the inductance component due to the connection (bonding wire 6) between the package and the surface acoustic wave filter element 7 is improved. There is a problem that the out-of-band characteristics deteriorate when the surface acoustic wave filter element 7 is accommodated in a package due to the electromagnetic coupling between the input / output wirings 3 and the like. On the other hand, as a characteristic required for the package, improvement in isolation between the input / output wirings 3 is desired. Therefore, in the example shown in FIG. 4, the ground electrode of the surface acoustic wave filter element 7 is connected to the ground conductor layer 2, as shown in the top view of the insulating base 1 in FIG. From the mounting portion on the bottom surface of the concave portion 1a on which the surface acoustic wave filter element 7 is mounted, the dielectric layer 1
A large-area ground conductor layer 2 extending between them was provided. FIG. 5 is a top view of the surface acoustic wave filter package shown in FIG. 4 with the cover 5 and the surface acoustic wave filter element 7 removed. In FIG. 5, 1 is an insulating base, 2 is a ground conductor layer, 3 is an input / output wiring formed of a metallized wiring layer, 4 is a frame-shaped metallized layer formed on the upper surface around the concave portion 1a of the insulating base 1, 8 Is a castellation conductor as a side conductor, and 9 is a through conductor. Two or more ground electrodes of the surface acoustic wave filter element 7 are electrically connected to the ground conductor layer 2 via the side castellation conductor 8 or the through conductor 9 and further to the ground conductor 21 for connecting an external electric circuit shown in FIG. Connected. However, with the recent increase in the frequency of the surface acoustic wave filter package, as shown in FIGS. 4 and 5, the bottom surface of the concave portion 1a in which the surface acoustic wave filter element 7 is mounted. To dielectric layer 1
In the structure in which the ground conductor layer 2 having a wide area extending between them is provided, and in the structure in which the plurality of ground conductors of the surface acoustic wave element 7 are connected to the metallization layer 4 by the through conductors 9, the surface acoustic wave filter element 7 A structure in which two or more grounding electrodes are connected by impedance via the ground conductor layer 2 having a large area in the package, LC resonance occurs with the surface acoustic wave filter element 7 and the capacitance component of the package, and This has caused degradation of the isolation characteristics between the input / output wirings 3, 3 serving as signal lines. For example, as shown in FIG. 6 in which the frequency characteristics of the isolation are diagrammatically shown, it is difficult to satisfy the isolation standard of -40 dB in the frequency range of 1 to 2 GHz generally used in portable telephones. There was a problem. In FIG. 6, the horizontal axis represents frequency (unit: GHz), and the vertical axis represents isolation (unit: GHz).
dB), and the dashed characteristic curve indicates the isolation characteristic between the input / output terminals (input / output wirings 3) of the surface acoustic wave filter package. The present invention has been devised in view of the above-mentioned problems of the prior art, and has as its object to reduce the amount of attenuation and the deterioration of isolation between input and output wirings in a high-frequency stop band. An object of the present invention is to provide an improved surface acoustic wave filter package. A surface acoustic wave filter package according to the present invention is provided with a mounting portion in which a surface acoustic wave filter element having at least two grounding electrodes is mounted on a central portion of an upper surface of an insulating base. And at least two of the at least two grounding electrodes electrically connected to each other and electrically connected to a grounding conductor of an external electric circuit, respectively, inside the insulating base. Characterized in that two ground conductor layers are provided. According to the surface acoustic wave filter package of the present invention, the insulating base has a mounting portion in the center of the upper surface of the insulating base on which a surface acoustic wave filter element having at least two grounding electrodes is mounted. And at least two mutually independent ground conductor layers electrically connected to the at least two ground electrodes and electrically connected to the ground conductors of an external electric circuit, respectively, are disposed inside the Therefore, by eliminating the electrical conduction of the ground conductor in the package and eliminating the inductance component, the LC resonance with the surface acoustic wave element and the capacitance component of the package can be suppressed. To improve attenuation and isolation degradation in the stopband frequency band of a banded surface acoustic wave filter Can. Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an embodiment of the surface acoustic wave filter package of the present invention, and FIG. 2 is a sectional view of the embodiment of the surface acoustic wave filter package of the present invention shown in FIG. It is a top view about a base | substrate. In these figures, 11 is an insulating base, 12 is a ground conductor layer, 13 is an input / output wiring composed of a metallized wiring layer,
14 is a frame-shaped metallized layer formed on the upper surface around the concave portion 1a of the insulating base 11, 15 is a lid, 16 is a bonding wire, 17 is a surface acoustic wave filter element, 18 is a castellation conductor as a side conductor, 19 is a through conductor. The insulating substrate 11 having a substantially rectangular shape has a concave portion 11a in the center of the upper surface in which the surface acoustic wave filter element 17 is mounted and accommodated.
Are mounted and fixed via an adhesive or the like (not shown). In this case, a lid 15 is attached and bonded to the frame-shaped metallized layer 14 of the insulating base 11 via a sealing material, and a surface acoustic wave filter element is provided inside a container formed by the insulating base 11 and the lid 15.
By hermetically sealing 17, a desired function as a surface acoustic wave filter device can be exhibited for a long period of time. In this embodiment, the central portion of the upper surface of the insulating base 11 on which the surface acoustic wave filter element 17 is mounted has a concave shape, but the mounting portion may have a flat shape. In such a case, it may be sealed with a concave cover made of metal or the like via solder or the like. However, it is easier to use a well-known sealing technique such as seam welding when the mounting portion is formed in a concave shape as shown in this example than in a flat shape. Sealing with a flat lid 15 enables more airtight sealing. The insulating substrate 11 is made of an aluminum oxide sintered body.
It is made of an electrical insulating material such as a mullite sintered body, an aluminum nitride sintered body, a silicon carbide sintered body, and a glass ceramic sintered body. For example, in the case of an aluminum oxide sintered body, a binder suitable for a raw material powder such as aluminum oxide, silicon oxide, calcium oxide, magnesium oxide, etc.
A solvent is added and mixed to form a slurry, and this is formed into a sheet by employing a conventionally known doctor blade method to obtain ceramic green sheets. Thereafter, these ceramic green sheets are appropriately punched. It is manufactured by punching out a plurality of sheets as necessary, laminating a plurality of sheets if necessary, and finally firing the laminate of ceramic green sheets at a temperature of about 1600 ° C. in a reducing atmosphere. Ground conductor layer 12 composed of a metallized wiring layer
Is made of a high melting point metal powder such as tungsten or molybdenum, and a metal paste obtained by adding and mixing an appropriate binder and solvent to the high melting point metal powder such as tungsten is previously known on a ceramic green sheet serving as an insulating substrate 11 in advance. By printing and applying in a predetermined pattern by the screen printing method described above, it is formed on the bottom surface of the concave portion 11a of the insulating substrate 11 by adhesion. Input / output wiring 13 composed of a metallized wiring layer
Is composed of a high melting point metal powder such as tungsten and molybdenum. A metal paste obtained by adding an appropriate binder and solvent to this high melting point metal powder such as tungsten is used as an insulating substrate.
By printing and applying a predetermined pattern on a ceramic green sheet to be 11 in advance by a conventionally well-known screen printing method, the insulating base 11 is adhered and formed from the periphery of the concave portion 11a to the lower surface. The metallized wiring layer of the input / output wiring 13 is provided with a nickel layer and a gold layer on the surface thereof in order by adopting a plating method. The bonding of the bonding wire 16 to the wiring 13 is made strong. The frame-shaped metallized layer 14 is used for attaching and bonding the lid 15 to the insulating base 11 via a brazing material or the like, and is made of a high melting point metal powder such as tungsten or molybdenum. The metal paste obtained by adding an appropriate binder and solvent to the high melting point metal powder is mixed and printed in a predetermined pattern by a well-known screen printing method in advance on a ceramic green sheet serving as the insulating substrate 11 to obtain an insulating material. It is formed on the upper surface of the concave portion 11 a of the base 11. The frame-shaped metallized layer 14 has a surface on which a nickel layer and a gold layer are sequentially applied by employing a plating method, and a sealing material for attaching and joining the lid 15. The adhesiveness with the material is further strengthened. In FIG. 2, reference numeral 13 denotes an input / output wiring composed of a metallized wiring layer, reference numeral 18 denotes a castellation conductor as a side conductor, and reference numeral 19 denotes a through conductor. The ground conductor layer 12 connected to the external electric circuit is provided inside the insulating base 11 from the mounting portion of the surface acoustic wave filter element. Further, two or more ground electrodes of the surface acoustic wave filter element 17 are connected to the ground conductor layer 12 which is electrically independent from each other by the castellation conductor 18 or the through conductor 19. Further, since the surface acoustic wave filter package of the present invention is surface-mounted on an external electric circuit board, the ground conductors of the external electric circuit are each provided with a grounding conductor layer 12 that is not electrically conductive. It is electrically connected by 18. In addition, the metallization layer 14 is formed of a ground conductor layer electrically independent from each other by one through conductor 19.
It is connected to one of the 12 locations. The surface acoustic wave filter element 17 has at least two ground electrodes corresponding to the input terminal for signal input and the output terminal for signal output, respectively.
In the surface acoustic wave filter package of the present invention,
At least two ground electrodes of the surface acoustic wave filter element 17 are electrically connected to the ground conductor layers 12 which are electrically independent from each other via the castellation conductor 18 or the through conductor 19, respectively. FIG. 3 is a diagram similar to FIG. 6 showing the isolation characteristics between the input / output wirings 13 in such a surface acoustic wave filter package of the present invention. 3, the horizontal axis represents the frequency (unit: GHz), the vertical axis represents the isolation (unit: dB), the solid straight line represents the isolation standard value, and the broken line characteristic curve shown in FIG. The isolation characteristic between the input / output wirings 3 in the surface acoustic wave filter package is shown, and the solid characteristic curve shows the isolation characteristic between the input / output wirings 13 in the surface acoustic wave filter package of the present invention. ing. As can be seen from the results shown in FIG. 3, according to the surface acoustic wave filter package of the present invention, in a frequency range of 1 to 2 GHz generally used in a mobile phone,
According to the surface acoustic wave filter package of the present invention, the surface acoustic wave filter having at least two grounding electrodes at the center of the upper surface of the insulating base 11 can sufficiently satisfy the isolation standard of −40 dB. It has a mounting part on which the filter element 17 is mounted, and at least two grounding electrodes of the surface acoustic wave filter 17 are electrically connected to the inside of the insulating base 11, respectively, and are electrically connected to grounding conductors of an external electric circuit. By providing at least two electrically independent ground conductor layers 12 which are electrically connected to each other, the electrical conduction of the ground conductor in the package is eliminated, and the inductance component is eliminated. The LC resonance with the capacitance component of the filter element 17 and the package can be suppressed, and the attenuation in the high-frequency stop band can be suppressed. And it is possible to improve the deterioration of isolation between the input and output lines 13, 13. Thus, according to the surface acoustic wave filter package of the present invention, the concave portion 11 a provided on the upper surface of the insulating base 11.
Then, the surface acoustic wave filter element 17 is bonded and fixed via an adhesive, and the input / output electrodes of the surface acoustic wave filter element 17 are connected to predetermined input / output wirings 13 via bonding wires 16 and then insulated. The lid 15 is attached and joined to the upper surface of the base 11 via a sealing member, and the surface acoustic wave filter element 17 is airtightly housed inside a container formed by the insulating base 11 and the lid 15 to form a product. Of the surface acoustic wave filter. The lid 15 attached and joined to the frame-shaped metallized layer 14 formed on the upper surface around the concave portion 11a of the insulating base 11 is made of, for example, an iron-nickel-cobalt alloy or an iron-nickel alloy. It is formed of a metal material or an inorganic insulating material such as an aluminum oxide sintered body similar to the insulating base 11,
When it is formed of a metal material, it is manufactured by subjecting an ingot such as an iron-nickel-cobalt alloy to a conventionally known metal working method such as a rolling method or a punching method. When formed of an inorganic insulating material, it is manufactured by a method similar to that of the above-described insulating base 11. The sealing material for attaching and joining the lid 15 to the frame-shaped metallized layer 14 on the upper surface of the insulating base 11 is, for example, gold-based.
Materials such as a tin alloy, a gold-germanium alloy, and a tin-lead alloy are preferably used. When these are used, the airtightness is higher than that of a sealing material made of a resin material. Therefore, the lid 15 is attached and bonded to the insulating base 11 via the sealing material, and the insulating base 11 and the lid 15 are formed. The surface acoustic wave filter element 17 can be satisfactorily and airtightly sealed inside the container, and a desired function as a surface acoustic wave filter device can be exhibited over a long period of time. The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, although the surface acoustic wave filter used in the mobile phone has been described as an example in the above-described embodiment, the application is not limited thereto, and two or more surface acoustic wave filter elements may be used. The present invention is also applicable to other electronic devices such as a duplexer. In this case, two or more ground electrodes of each of the two or more surface acoustic wave filter elements are electrically connected to a ground conductor layer provided on the lower surface of the insulating base. In the above embodiment, the ground conductor layer is provided inside the insulating base from the mounting portion of the surface acoustic wave filter element, but is provided only inside the insulating base. No problem. According to the surface acoustic wave filter package of the present invention, the mounting portion for mounting the surface acoustic wave filter element having at least two grounding electrodes is provided at the center of the upper surface of the insulating base. Along with the inside of the insulating base,
The at least two grounding electrodes are electrically connected to each other, and at least two mutually independent ground conductor layers electrically connected to the ground conductors of the external electric circuit are provided. By eliminating the electrical continuity of the ground conductor in the package and eliminating the inductance component, LC resonance with the surface acoustic wave element and the capacitance component of the package can be suppressed. The attenuation in the frequency band of the stop band of the surface acoustic wave filter and the deterioration of the isolation can be improved. As described above, according to the present invention, it is possible to provide a surface acoustic wave filter package in which the attenuation in the high-frequency stop band and the deterioration of the isolation between the input and output wirings are improved. The surface acoustic wave filter package of the present invention is very useful in practical use because it can improve the isolation between input and output wirings when used in a surface acoustic wave filter used in a portable telephone. Has an effect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing an embodiment of a surface acoustic wave filter package according to the present invention. FIG. 2 is a top view of the insulating base in the example shown in FIG. FIG. 3 is a diagram showing isolation characteristics between input and output wirings in the present invention and a conventional surface acoustic wave filter package. FIG. 4 is a cross-sectional view showing an example of a conventional surface acoustic wave filter package. FIG. 5 is a top view of the insulating base in the example shown in FIG. FIG. 6 is a diagram showing an isolation characteristic between input / output wirings in a conventional surface acoustic wave filter. [Explanation of Signs] 11: Insulating base 11a: Recess 12: Ground conductor layer 13: Input / output wiring 14: Metallization layer 15: Lid 16: Wire bonding 17: Surface acoustic wave filter element 18: Castellation conductor (side conductor) 19: Through conductor

Claims (1)

Claims: 1. An insulating base having at least two
A mounting portion on which a surface acoustic wave filter element having two grounding electrodes is mounted, wherein the at least two grounding electrodes are electrically connected to the inside of the insulating base, and a ground conductor of an external electric circuit is provided. A surface acoustic wave filter package, wherein at least two electrically independent ground conductor layers electrically connected to each other are provided.