JPH08195645A - Package for mounting element - Google Patents

Abstract

PURPOSE: To provide a simple package structure for the package for mounting element where an element such as a surface acoustic wave filter element is mounted even when an impedance matching circuit is formed between an internal connection terminal and an external connection terminal. CONSTITUTION: Of the element mounted package having the impedance matching circuit 24 formed between the internal connection terminal 19 and external connection terminal 27 formed on the package where the surface acoustic wave filter elements 14a and 14b are mounted, the impedance matching circuit 24 is formed on a matching circuit substrate 22 which is formed as a different body from the element mounted substrate 10 where the elements 14a and 14b are formed, and the element mounted substrate 10 and matching circuit board 22 are joined together. Then the internal connection terminal 19 provided on the element mounted substrate 10 and the impedance matching circuit 24 provided on the matching circuit board 22 are electrically connected to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an element mounting package, and more particularly to an internal connection terminal formed on a package in which an element such as a surface acoustic wave filter element is mounted and which is connected to the element by a wire or the like. And an external connection terminal connected to an external circuit or the like, the present invention relates to an element mounting package in which an impedance matching circuit is formed.

[0002]

2. Description of the Related Art As an element mounting package for mounting a surface acoustic wave filter element used in mobile communication equipment, Japanese Patent Laid-Open No. 6-112762 proposes an element mounting package shown in FIG. . In the device mounting package shown in FIG. 3, surface acoustic wave filter devices 102 and 104 are mounted on a ceramic package 100. Such surface acoustic wave filter elements 102, 104
An impedance matching circuit 106 having a stripline structure sandwiched between ground layers 112 and 114 is provided between an internal connection terminal 118 that is connected to the external connection terminal 118 on the surface of the package 100 and an external connection terminal 116 formed on the surface of the package 100. Has been formed. In the impedance matching circuit 106, the total length of the pattern is usually longer than other signal input / output wiring patterns formed on the package 100. The impedance matching between the impedance matching circuit 106 and the surface acoustic wave filter elements 102 and 104 to be mounted is usually performed by adjusting the pattern length and / or the pattern width of the impedance matching circuit 106.

[0003]

As described above, the impedance matching circuit 10 in which the impedances of the surface acoustic wave filter elements 102 and 104 to be mounted are matched.
According to the element mounting package including No. 6, it is possible to meet the demand for miniaturization of the mobile communication device. However, since the total length of the pattern of the impedance matching circuit 106 is longer than that of other signal input / output wiring patterns, the impedance matching circuit 106 is mixed with other signal input / output wiring patterns in the package 100. If formed, the package tends to have a remarkably complicated structure, and the manufacturing process of the package tends to be complicated. This tendency tends to be more remarkable as the package is made smaller. Further, normally, the impedance matching circuit 106 is formed by being co-fired with the green sheet or the like containing the alumina component forming the package 100, like other wiring patterns, and therefore the firing of the green sheet containing the alumina component is performed. A metal such as tungsten that can be fired at a temperature (1,500 to 1,600 ° C.) is used. However, a circuit formed by firing a metal such as tungsten has a higher electric resistance value than a circuit formed by a low melting point metal such as copper having a lower melting point than the metal such as tungsten.

Therefore, the impedance matching circuit 10
For impedance matching, the porous conductor formed by firing a metal such as tungsten is impregnated with a low melting point metal such as copper having a lower melting point than the metal such as tungsten in order to reduce the electric resistance value of 6. Circuits may be used. As described above, the surface acoustic wave filter elements 102 and 104 and the internal connection terminals 118 mounted in the cavity 108 of the package 100 in which the impedance matching circuit 106 having the reduced electric resistance value is built-in are formed by wire bonding or the like. Cavity 10 after electrical connection
In order to maintain the airtight state inside 8, the cap 110 is attached. However, since the low melting point metal such as copper impregnated in the porous conductor and the package body 100 made of ceramic are easily separated from each other, the atmosphere or moisture enters the cavity 108 through the impedance matching circuit 106, and The airtight state of 108 may be broken. Therefore, an object of the present invention is to simplify the formation of an impedance matching circuit between an internal connection terminal and an external connection terminal in an element mounting package in which an element such as a surface acoustic wave filter element is mounted. An object is to provide an element mounting package that can have a package structure.

[0005]

Means for Solving the Problems As a result of repeated studies to achieve the above object, the inventors of the present invention have decided to mount an element mounting board on which an element is mounted and a matching circuit board for forming an impedance matching circuit. The impedance matching circuit can be formed independently from other input / output wiring patterns by forming the element mounting package by joining the two substrates after the separate formation. The element mounting package formed in this manner has a simpler package structure and package manufacturing process than the conventional element mounting package formed by mixing the impedance matching circuit and other input / output wiring patterns. I knew that it would be possible. Further, they have also found that even if the impedance matching circuit is formed of a material that is easily separated from the substrate body of the matching circuit board, the cavity formed in the element mounting board can be sufficiently kept airtight, and thus the present invention has been reached. That is, the present invention relates to an internal connection terminal that is formed in a package in which an element such as a surface acoustic wave filter element is mounted and that is connected to the element by a wire or the like and an external connection terminal that is connected to an external circuit or the like. In the element mounting package in which the impedance matching circuit is formed, the impedance matching circuit is formed on a matching circuit board formed separately from the element mounting board on which the element is mounted, and The element mounting board and the matching circuit board are joined together, and the internal connection terminals provided on the element mounting board and the impedance matching circuit provided on the matching circuit board are electrically connected. It is in the device mounting package.

In the present invention having such a structure, by forming the element mounting board and the matching circuit board from ceramic, the conductor circuit formed on the element mounting board is highly peelable from the substrate body and has high airtightness. Since it can be formed of the above metal, the airtightness of the cavity formed in the element mounting substrate can be improved. In particular, the element mounting board and the matching circuit board are made of ceramics, and the impedance matching circuit is formed in a porous conductor made of a sintered metal such as sintered tungsten in which the melting point is lower than that of the sintered metal. By impregnating and forming the metal of (1), the airtightness of the cavity formed in the element mounting substrate can be improved while lowering the resistance value of the impedance matching circuit. Further, by forming the element mounting board and the matching circuit board by using a ceramic having the same composition, particularly a ceramic containing an alumina component as a main component, it is possible to facilitate the bonding of the two and to match the element mounting board. The connection with the circuit board for use can be easily performed by brazing.

Further, by bonding a plurality of element mounting boards to the upper surface of the matching circuit board, an element mounting package having a plurality of functions can be provided. In such an element mounting package according to the present invention, the impedance matching circuit formed on the matching circuit board has a stripline structure sandwiched between ground layers, so that it can be used for high frequencies. . By electrically connecting the impedance matching circuit and the internal connection terminal via the via formed by filling the conductive paste, the two can be electrically connected at the shortest distance.

[0008]

According to the present invention, the element mounting board on which the element such as the surface acoustic wave filter element is mounted and the matching circuit board provided with the impedance matching circuit are formed separately.
The two are electrically joined to form a package. Therefore, a conductor circuit including a via formed on the element mounting board can be created without considering the impedance matching circuit, and an impedance matching circuit formed on the matching circuit board can also be created without considering the conductor circuit. Therefore, the package structure and the package manufacturing process can be simplified as compared with the case where both circuits are mixed to form the package. Further, the conductor circuit of the device mounting board can be formed of a metal such as tungsten which has low peelability from the device mounting board and has good airtightness. Therefore, even if the impedance matching circuit formed of a material that has high peelability from the matching circuit board but has a low electric resistance value peels off from the board body, the atmosphere and moisture will pass through the impedance matching circuit to the device mounting board. The cavity can be prevented from entering even the formed cavity, and the airtightness of the cavity can be secured.

[0009]

The present invention will be described in more detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing an embodiment of an element mounting package according to the present invention, in which a surface acoustic wave filter element is provided in a cavity 12 of an element mounting substrate 10 made of ceramics containing alumina as a main component. Each of 14a and 14b is mounted. Each of the elements 14a and 14b includes internal connection terminals of conductor circuits 18, 18 ... Including vias formed by filling a conductive paste formed on the element mounting substrate 10 and an impedance matching circuit described later. Each of the internal connection terminals 19 connected to one end and the wire 1
Are electrically connected with each other, and are hermetically sealed by a cap 20 attached so as to cover the cavity 12. The conductor circuits 18 including the vias formed on the element mounting substrate 10 are formed only of sintered tungsten and are formed by being co-fired with the element mounting substrate 10. Therefore, the airtightness between the conductor circuits 18, 18 including the vias and the element mounting board 10 is good, and the conductor circuits 18, 18 including the vias.
The atmosphere and moisture can be prevented from entering the cavity 12 through the.

One surface of the element mounting board 10 and one surface of a ceramic matching circuit board 22 mainly composed of an alumina component, which is separately formed, are joined by brazing such as silver solder or solder. The package is formed. An impedance matching circuit 24 is formed on the matching circuit board 22, and one end of the impedance matching circuit 24 is internally connected via a via forming a conductor circuit 18 formed in the element mounting board 10. It is connected to 19. Further, the other end of the impedance matching circuit 24 is connected to one of the external connection terminals 27 formed on the surface of the matching circuit board 22. In this way, by connecting one end of the impedance matching circuit 24 and the internal connection terminal 19 via the via, both ends can be connected in the shortest distance. Therefore, the impedance of the via may be substantially ignored, and in this case, the impedance matching with the mounted element can be performed only by the impedance matching circuit 24. Further, the impedance matching circuit 24 has a stripline structure sandwiched between the ground layers 28 and 29, and has a high frequency compatible structure.

The impedance matching circuit 24 of this embodiment
Is formed by impregnating molten copper into a porous conductor made of sintered tungsten, which is obtained by mixing organic matter that is gasified at the sintering temperature into tungsten and firing the mixture. In the impedance matching circuit 24, since copper enters into the holes formed in the sintered tungsten, it is possible to reduce the electric resistance value as compared with the circuit formed of only the sintered tungsten. However, since the copper forming the impedance matching circuit 24 is easily separated from the ceramic substrate body forming the matching circuit board 22, the airtightness between the impedance matching circuit 24 and the substrate body is poor.

In this regard, in this embodiment, the conductor circuit 18 including the via of the element mounting substrate 10 which is required to be airtight,
18 ... Is formed of sintered tungsten having good airtightness with the substrate body made of alumina, and the impedance matching circuit 24 having a low electric resistance value although the airtightness is inferior,
Matching circuit board 22 formed separately from element mounting board 10
Is formed. For this reason, the electrical resistance of the impedance matching circuit 24 can be reduced while ensuring the airtightness of the element mounting substrate 10 that requires airtightness of the mounted surface acoustic wave filter element or the like. The device mounting board 1
The conductor circuits 18 including the 0 vias are formed only of sintered tungsten having a high electric resistance value, but since the length thereof is significantly shorter than that of the impedance matching circuit 24, the via circuits include the vias. The electric resistance of the conductor circuits 18, 18 ... Does not pose a problem.

In the present embodiment, the conductor circuits 18, 18 ··· including the vias are the conductor circuits 26, 26 · · formed on the impedance matching circuit 24 or the matching circuit board 22.
., And the like, and are connected to external connection terminals 27, 27, ... Formed on the bottom surface of the matching circuit board 22. Therefore, a pin is provided upright on each of the external connection terminals 27, 27, ... Formed on the bottom surface of the matching circuit board 22, and PGA (P
An in grid array) structure may be used, or a BGA (ball grid array) structure may be provided by providing solder balls or the like. Further, as shown in FIG. 2, external connection terminals 30 are formed on the inner peripheral surface on both sides of the matching circuit board 22 so as to be in contact with and electrically connected to a circuit pattern or the like provided on a mounting board or the like. The recesses 32, 32, ... Can be formed to form a leadless chip module (LCC) structure. Further, on the matching circuit board 22, a plurality of element mounting boards 10a, 10a,
b may be formed.

In the above-described embodiment, the element mounting package in which the element mounting substrate and the matching circuit board are made of ceramic having the same composition has been described. However, the element mounting board and the matching circuit are described. The substrate may be formed of a ceramic having a different composition,
The airtightness is lower than that of ceramic, but plastic may be used. Also, the element to be mounted has been described focusing on the surface acoustic wave filter element, but it may be another element such as a semiconductor element. Furthermore, the impedance matching circuit may be formed on one layer of the matching circuit board formed in multiple layers, or may be formed in two or more layers separately.

[0015]

According to the present invention, a portion on which an element such as a surface acoustic wave filter element is mounted can be kept airtight, and the package structure can be simplified and the manufacturing process of the package can be simplified. It is possible to provide a package for mounting various elements. Such a package can be suitably used as an element mounting package on which an element such as a surface acoustic wave filter element used in mobile communication equipment is mounted.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing another embodiment.

FIG. 3 is a cross-sectional view of a conventional element mounting package provided with an impedance matching circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Element mounting board 12 Cavities 14a, 14b Surface acoustic wave filter element 16 Wire 18 Conductor circuit including vias of element mounting board 20 Cap 22 Matching circuit board 24 Impedance matching circuit 26 Conductor circuit of matching circuit board 22

Claims (9)

[Claims] 1. An internal connection terminal formed on a package in which an element such as a surface acoustic wave filter element is mounted and connected to the element by a wire or the like, and an external connection terminal connected to an external circuit or the like. In an element mounting package in which an impedance matching circuit is formed, the impedance matching circuit is formed on a matching circuit board formed separately from an element mounting board on which the element is mounted, and The element mounting board and the matching circuit board are joined, and the internal connection terminals provided on the element mounting board and the impedance matching circuit provided on the matching circuit board are electrically connected. A device mounting package. 2. The device mounting package according to claim 1, wherein the device mounting board and the matching circuit board are made of ceramics. 3. The element mounting board and the matching circuit board are made of ceramic, and the impedance matching circuit has a melting point lower than that of the sintered metal in a porous conductor made of a sintered metal such as sintered tungsten. 2. The device mounting package according to claim 1, which is a conductor formed by impregnating a metal such as copper. 4. The element mounting board and the matching circuit board are formed of ceramics having the same composition.
4. The element mounting package according to any one of 3 above. 5. The device mounting package according to claim 1, wherein the device mounting board and the matching circuit board are formed of a ceramic containing an alumina component as a main component. 6. The device mounting package according to claim 1, wherein the device mounting board and the matching circuit board are joined by brazing. 7. The device mounting package according to claim 1, wherein a plurality of device mounting boards are bonded to the upper surface of the matching circuit board. 8. The impedance matching circuit has a stripline structure sandwiched between ground layers.
7. The element mounting package according to any one of 7. 9. The device according to claim 1, wherein the impedance matching circuit and the internal connection terminal are electrically connected to each other through a via formed by being filled with a conductive paste. Mounting package.