JP2001244409A - High frequency module - Google Patents

Abstract

(57) Abstract: A transmission loss of a high-frequency signal in a high-frequency module in which a high-frequency element package containing a high-frequency element is mounted on a circuit board is reduced. A circuit board B is formed on a surface of a first dielectric substrate 11 and includes first high-frequency lines 12a, 12b and 12c having at least a pair of connection terminals 13a and 13b. And a connection terminal 6a, 6b formed on the second dielectric substrate 1, connected to the high-frequency element 2, and connected to an external circuit at an end. Second high-frequency line 4 provided
a, comprising a high-frequency device package A having a 5a, and it implements a high-frequency device package A to the surface of the circuit board B, and the total high-frequency circuit length in the module L _1, all high frequency circuit on the circuit board when the length was L _2, the L ₂ / L ₁ is 0.5 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a high-frequency module in which a microwave or millimeter-wave signal is transmitted and a package having a high-frequency element mounted on a circuit board surface is mounted.

[0002]

2. Description of the Related Art In recent years, in the era of advanced information, the use of radio waves used for information transmission from the microwave range of 1 to 30 GHz to the millimeter wave range of 30 to 300 GHz has been studied. Application systems using millimeter wave radio waves, such as inter-vehicle radars, have also been proposed.

In such a high-frequency system, a multi-chip module in which all high-frequency elements are mounted and housed on the surface of a single circuit board and the high-frequency elements are collectively hermetically sealed with a lid or the like is known. Have been.

FIG. 3 is a schematic sectional view of a multi-chip module. According to FIG. 3, the multi-chip module 3
Reference numeral 1 denotes a wiring board 32, a frame 33, a lid 34, and a plurality of high-frequency elements 35 therein. Each of the high-frequency elements 35 is a high-frequency line 3 formed on the surface of the wiring board 32.
6 and wire bonding.

In such a multi-chip module, since a plurality of high-frequency devices are mounted on the surface of one substrate, the size of the entire high-frequency device mounting substrate increases, and as a result, module warpage and frame There was a problem in the yield of hermetic sealing due to deformation of the body and lid.

In order to solve such a problem, it is conceivable that a plurality of high-frequency elements are hermetically housed in a plurality of independent packages, and the plurality of packages are mounted on a circuit board to form a module.

[0007]

However, in the case of a module in which high-frequency elements are individually housed in a package and mounted on a circuit board, the signal frequency is 10 GHz.
If the frequency is higher than z, the signal transmission loss increases at the connection between the package and the circuit board, and the loss of the line portion is added because the connection between the packages passes through the circuit board. It was thought that the circuit could not operate satisfactorily because the loss of the circuit became larger.

Accordingly, it is an object of the present invention to provide a high-frequency module in which a high-frequency element package containing a high-frequency element is mounted on a circuit board to reduce the transmission loss of a high-frequency signal in a high-frequency module. .

[0009]

Means for Solving the Problems In view of the problems described above, the present inventors have repeatedly studied a high-frequency module structure in which a high-frequency element is housed in a package and mounted on a circuit board. By designing the circuit so that the length of the high-frequency line of the module satisfies a specific relationship with the length of the high-frequency line of the entire module when the package is mounted, it has been possible to reduce signal transmission loss in the entire module. Was.

That is, the high-frequency module of the present invention has a first
A circuit board comprising: a first dielectric substrate; a first high-frequency line having at least one pair of connection terminals; and a second dielectric substrate.
A high-frequency element mounted on the surface of the second dielectric substrate, a second high-frequency line formed on the second dielectric substrate and connected to the high-frequency element, and provided for connection to an external circuit. And a plurality of high-frequency element packages having connection terminals provided thereon, wherein the plurality of high-frequency element packages are mounted on the surface of the circuit board, and the total high-frequency circuit length in the module is L. ₁ ,
When the total high-frequency circuit length in the circuit board is L ₂ , L ₂ /
Length ratio represented by L ₁ is equal to or more than 0.5.

Preferably, the first dielectric substrate in the circuit board is made of an organic resin-containing insulating material, and the second dielectric substrate in the package is made of ceramics. Is preferably smaller than that of the first dielectric substrate.

Further, as another embodiment of the present invention, the third aspect
And a third dielectric substrate formed on the third dielectric substrate.
A high-frequency line and a wiring board having a connection terminal provided for connection to an external circuit, further comprising a package mounted on the surface of the circuit board together with the package. also, the L ₂ / L ₁
Is characterized by having a relationship in which the length ratio represented by is 0.5 or less.

[0013] Even when a wiring substrate is provided, it is desirable that the dielectric loss of the third dielectric substrate in this wiring substrate be smaller than that of the first dielectric substrate.

Each of the above high-frequency modules is particularly suitable when a high-frequency signal having a frequency of 10 GHz or more is transmitted to the high-frequency line.

[0015]

According to the present invention, when configuring a module in which a plurality of high-frequency elements are mounted on a circuit board, one or more high-frequency elements are separated into a plurality of packages and hermetically sealed. By mounting on the board,
The reliability of hermetic sealing can be improved as compared with the case where a plurality of high-frequency elements are hermetically sealed in one package as in the related art.

According to the present invention, the length ratio L ₂ / L ₁ of the total high-frequency circuit length L ₂ of the circuit board to the total high-frequency circuit length L _{1 of the} high-frequency module is set to 0.5 or less. As a result, it is possible to obtain good transmission characteristics comparable to those of the conventional multi-chip module.

In the case where the circuit board is large relative to the package and it is difficult to form the above relationship of the circuit length, a dielectric material having a lower loss than the dielectric substrate of the circuit board is separately provided. A high-frequency line is formed on a dielectric substrate, and a high-frequency signal is mounted on the high-frequency line on the circuit board, and a high-frequency signal is bypassed to the high-frequency line on the wiring substrate to form a low-dielectric-loss dielectric substrate. As a result, it is possible to control the line length within the above range regardless of the size of the circuit board.

[0018]

Hereinafter, a high-frequency module according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic sectional view for explaining one example of the high-frequency module of the present invention. The high-frequency module of FIG. 1 basically includes a high-frequency element package A and a circuit board B. (High-frequency Element Package A) According to the high-frequency element package A, the high-frequency element 2 is mounted on the surface of the dielectric substrate 1 and hermetically sealed by the lid 3. An input high-frequency line 4a and an output high-frequency line 4b are formed on the surface of the dielectric substrate 1, and each line 4a,
One end of 4b is connected to the high-frequency element 2 respectively. The other ends of the lines 4a and 4b are connected to through-hole conductors 5a formed through the dielectric substrate 1, respectively.
Via 5b, connection terminals 6a and 6b led out to the back surface of the dielectric substrate 1 and connected to an external circuit formed on the back surface of the dielectric substrate 1 are connected. A ground layer 7 is formed inside the dielectric substrate 1, and each of the lines 4a and 4b together with the ground layer 7 forms a microstrip line type high-frequency line. An opening 8 is formed in the through-hole conductors 5a and 5b of the internal ground layer 7.
Are formed, and are not electrically in contact with the through-hole conductors 5a and 5b.

In the high-frequency module shown in FIG. 1, two high-frequency element packages A having the above-described structures are provided.
1, A2. (Regarding Other Structure of High-Frequency Element Package) In the high-frequency element package A of FIG. 1, through-hole conductors 5 are used for transmitting signals in the vertical direction. The line formed on the surface of the first dielectric substrate and the line formed on the back surface can be electromagnetically coupled via the slot by a well-known structure in which the line formed on the back surface is opposed to the line formed on the back surface. The method of mounting a package for transmitting a high-frequency signal vertically to a substrate using the above-described through-hole conductor or electromagnetic coupling on a circuit board is different from the method shown in FIG. 1 in that the package is turned upside down and a recess is provided. It is also possible to place the package in the recess of the circuit board so that the connection terminal of the package and the connection terminal of the circuit board are substantially flush with each other, and connect the respective connection terminals by wire bonding or the like.

Further, the high-frequency line inside the package is extended in the horizontal direction without transmitting vertically through the through-hole conductor 5 or the substrate using the electromagnetic coupling, and the high-frequency signal is transmitted while maintaining the airtightness through the package frame. The present invention can also be applied to a package derived from the inside of the package to the outside of the package. In such a case, a concave portion is provided on the circuit board, and the package is placed on the concave portion so that the connection terminal of the package and the connection terminal of the circuit board are substantially flush with each other. Connect. (Circuit Board) On the other hand, according to the circuit board B, the dielectric board 1
A high-frequency line 12 is formed on at least the surface of the package 1. The high-frequency line 12 is provided with a region for mounting the package A. The high-frequency line 12 is connected to the connection terminals 6a and 6b of the package A. Are formed at intervals. That is, the high-frequency line of the circuit board B is 12
a, 12b, and 12c.
In addition, connection terminals 13a and 13b for connecting the high-frequency module to other circuits are provided at the ends of the high-frequency lines 12a and 12c. A ground layer 14 is formed inside the dielectric substrate 11, and forms a microstrip line together with the high-frequency lines 12a, 12b, and 12c. Note that the ground layer 14 may be the back surface of the dielectric substrate 11.

In the package A and the circuit board B, the high-frequency lines 4a, 4b, 12a, 12b, and 12c form a microstrip line together with the ground layers 7 and 14. 1
A so-called coplanar line structure in which ground layers are formed on both sides in plan view of 2a, 12b, and 12c may be used. You may. (Mounting Structure) On the surface of the circuit board B, the two packages A are mounted, and the connection terminals 6 of the package A are mounted.
a, 6b and the high-frequency line 12a and the high-frequency line 12b of the circuit board B, or the high-frequency line 12b and the high-frequency line 12c
Are mounted with the conductive adhesive 15 such as a solder and each end.

In the high-frequency module having such a structure, the signal input from the electrode 13a is
a of the connection terminal 6a of the high-frequency element package A1
-High-frequency line 4a including through-hole conductor 5a-High-frequency element 2-High-frequency line 4b including through-hole conductor 5b-
The signal is output from the connection terminal 6b, further transmitted through the package A2 via the high-frequency line 12b, and transmitted from the connection terminal 6b to the connection terminal 1 via the high-frequency line 12c.
3b is connected to an external circuit.

According to the present invention, the length of the high-frequency line on the circuit board B is made as short as possible in order to reduce the transmission loss of the high-frequency signal of the entire high-frequency module. Normally, a high-frequency line on a circuit board exists for transmitting a high-frequency signal from one position to another position. In the present invention, the high-frequency line is used as a connection pattern for connecting the packages on the circuit board. Specifically, the total circuit length of the high-frequency module in which the high-frequency signal is transmitted, that is, the total circuit length from the connection terminal 13a to the connection terminal 13b is L ₁ , the total circuit length on the circuit board, that is, the high-frequency When the sum of the lengths of the line 12a, the high-frequency line 12b, and the high-frequency line 12c (L ₂₁ + L ₂₂ + L ₂₃ ) is L ₂ , L ₂ /
Ratio represented by L ₁ is 0.5 or less, especially 0.4 or less, still more it is important to 0.2 or less.

That is, in the high-frequency line in the module, it is necessary to minimize the distance (length) of the high-frequency line on the circuit board which does not contribute to signal processing. Usually, the high-frequency element package is designed to have a minimum size required for mounting and sealing the element, and it is difficult to further reduce the size. Since the high-frequency line on the circuit board only transmits high-frequency signals, there is a possibility that the length can be shortened by devising circuit design and component layout. In order to make the length of the high-frequency signal transmitted on the circuit board 0.5 or less of the high-frequency circuit length of the entire module, the high-frequency line on the circuit board B side is not used as a transmission line, but rather for connecting the packages. By using it as a connection pattern, loss of high-frequency signal transmission in the entire module can be reduced.

As a material for forming the dielectric substrate of the high-frequency element package A and the dielectric substrate of the circuit board B, a ceramic material containing alumina, AlN, Si ₃ N ₄ , mullite, etc. as a main component, a glass material, a glass ceramic A material, an organic resin material such as an epoxy resin, a polyimide resin, a fluorine resin such as Teflon, or an organic resin-ceramic composite material is used.

It is preferable that the dielectric substrate of the high-frequency element package has a small dielectric loss and can be hermetically sealed. Particularly desirable dielectric materials include:
Examples include inorganic materials such as alumina, AlN, and glass ceramics.

It is preferable that the dielectric substrate of the circuit board has low dielectric loss and is inexpensive. Particularly desirable dielectric materials include insulating materials containing organic resin such as glass-fluorine resin and glass-epoxy resin.

As the most preferable combination, it is desirable from the viewpoint of performance and cost that the dielectric substrate of the high-frequency device package is made of alumina and the dielectric substrate of the circuit board is made of glass-epoxy resin.

In the high-frequency circuit length on the high-frequency module, the circuit network in the high-frequency element is substantially ignored, and the circuit length in the high-frequency element is regarded as the distance between the electrodes connected to the high-frequency line of the element. The boundary between the high-frequency element package and the circuit board is located at the center of the connection.

In the high-frequency module of the present invention, FIG.
In the high-frequency module described in the above, the size of the circuit board is small, and the ratio of the circuit length can be satisfied only with the package, but the size of the circuit board is much larger than the size of the high-frequency element package in circuit design. If large,
It is difficult to satisfy the above-described ratio of the circuit lengths only with the high-frequency circuit length in the high-frequency element package.

In such a case, a wiring board C is mounted on the surface of the circuit board B in addition to the high-frequency package A on the surface of the circuit board B as shown in FIG. This wiring board C
The circuit board B includes a dielectric substrate 20 made of a dielectric material having a lower dielectric loss than the dielectric substrate, and a high-frequency line 21 formed on the surface thereof. At both ends of the high-frequency line 21, connection terminals 22 are provided, respectively.

Then, the wiring board C is placed on the high-frequency line 23 formed at a predetermined interval on the surface of the circuit board B such that the surface on which the high-frequency line 21 is formed faces the circuit board B, The high-frequency line 23 of the circuit board B and the connection terminal 22 of the wiring board C are connected by a conductive adhesive such as solder.

With this configuration, the signal transmitted on the circuit board B is bypassed to the high-frequency line 21 on the wiring board C side at the wiring board C mounting portion. Since the dielectric loss of the dielectric substrate 20 of the wiring board C is lower than that of the dielectric substrate 25 of the circuit board, the signal attenuation can be reduced by transmitting the high frequency line on the wiring board C side.

In this configuration, when the total high-frequency circuit length in the high-frequency module is L ₁ and the total high-frequency circuit length (L ₂₁ + L ₂₂ + L ₂₃ + L ₂₄ ) on the circuit board B is L ₂ , ₂ / L ₁ can be adjusted to be 0.5 or less, particularly 0.4 or less, and further 0.2 or less.

By using the wiring board C in this way, even when the size of the circuit board B is large, the ratio of the high-frequency circuit length can be easily adjusted to 0.5 or less.

In FIG. 2, the high-frequency line 21 of the wiring board C is formed by a mere line formed on the surface of the dielectric substrate 20. A predetermined high-frequency circuit may be formed on the front surface, the back surface, and inside.

In the high-frequency module shown in FIGS. 1 and 2, the case where the high-frequency circuit is formed by a single line has been described for convenience of explanation. And the total length of the two or more high-frequency lines is the total high-frequency circuit length. However, the power supply in the circuit board or high-frequency element package,
Circuits to which signals such as control signals and intermediate frequency signals are transmitted are excluded from high frequency circuits. That is, the high-frequency circuit according to the present invention means a circuit that transmits a signal having a frequency near the carrier wave.

[0039]

EXAMPLES The following experiments were conducted to confirm the effects of the present invention. First, the dielectric loss tangent at 10 GHz is 0.00
In addition, a dielectric substrate is manufactured using alumina ceramics of No. 06, a microstrip line is formed on the front and back surfaces of the dielectric substrate using tungsten as a conductor material, and the ends of the microstrip lines on the front and back surfaces are formed with through holes. They were connected by a conductor, and an evaluation sample of the high-frequency element package A as shown in FIG. 1 was produced.
In the evaluation sample, the input terminal and the output terminal were directly connected in the package by tungsten metallization without forming the recess for mounting the high-frequency element of FIG. 1, and the metal lid was adhered to the surface of the dielectric substrate frame. Then, two airtightly sealed evaluation samples were prepared.

On the other hand, the dielectric loss tangent at 10 GHz is 0.
A dielectric substrate was fabricated using a composite material of glass woven fabric 05 impregnated with epoxy resin, and a microstrip line was formed on the surface using copper as a conductor material. Substrate B was produced. In addition,
The microstrip line of the circuit board was routed, and several types of circuit boards having different high-frequency line lengths on the circuit board were prepared.

Further, a dielectric substrate is formed using alumina having a dielectric tangent of 0.0006 at 10 GHz as a wiring substrate, and a coplanar line is formed on the surface of the dielectric substrate using tungsten as a conductor material. 2
The wiring board C having the structure shown in FIG.

Then, the evaluation sample and the wiring board were mounted on the surface of the circuit board by using solder.

Incidentally, the L ₂ / L ₁ ratio between the total high-frequency circuit length L ₂ of the total high-frequency circuit length L ₁ and the circuit board in each module are shown in Table.

The frequency of 1 GHz between the connection terminals formed at the end of the circuit board in the high-frequency module
The transmission loss of a high frequency signal of 10 GHz was evaluated, and the results are shown in Table 1.

[0045]

[Table 1]

According to the results shown in Table 1, when the frequency is 1 GHz and the low frequency, in any case, the loss is 0.5 dB or less and no problem occurs.
When the frequency becomes high as Hz, the loss of the comparative product exceeds 2 dB, which may cause a problem in circuit operation. According to the present invention, when the ratio L ₂ / L ₁ is 0.5 or less, particularly 0.2 or less, the loss is 2 dB or less, and excellent transmission characteristics are exhibited.

[0047]

As described above in detail, according to the high-frequency module of the present invention, by setting the length of the entire high-frequency circuit on the circuit board to 以下 or less of the total high-frequency circuit length of the module, Are individually packaged, it is possible to reduce the loss of the high-frequency signal as the whole module.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view for explaining an example of a high-frequency module according to the present invention.

FIG. 2 is a schematic sectional view for explaining another example of the high-frequency module of the present invention.

FIG. 3 is a schematic sectional view illustrating the structure of a conventional multichip module.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 dielectric substrate 2 high-frequency element 3 lid 4 high-frequency line 5 through-hole conductor 6 connection terminal 7 ground layer 8 opening A package B circuit board C wiring board

Claims (8)

[Claims] A circuit board comprising: a first dielectric substrate; a first high-frequency line provided on a surface of the first dielectric substrate and having at least a pair of connection terminals; 2
A dielectric substrate, a high-frequency element mounted on the surface of the second dielectric substrate, a second high-frequency line formed on the second dielectric substrate and connected to the high-frequency element, and an external circuit. And a plurality of high-frequency element packages having connection terminals provided for connection with, a high-frequency module comprising a plurality of high-frequency element packages mounted on the surface of the circuit board, wherein the module The total high-frequency circuit length is L ₁ and the total high-frequency circuit length in the circuit board is L ₂
When a high frequency module length ratio expressed by L ₂ / L ₁ is equal to or more than 0.5. 2. The high-frequency module according to claim 1, wherein said first dielectric substrate is made of an organic resin-containing insulating material, and said second dielectric substrate is made of ceramics. 3. The dielectric substrate according to claim 1, wherein the dielectric loss of said second dielectric substrate is smaller than that of said first dielectric substrate.
Or the high-frequency module according to claim 2. 4. The high-frequency module according to claim 1, wherein a high-frequency signal having a frequency of 10 GHz or more is transmitted to said high-frequency line. 5. A first dielectric substrate, and said first dielectric substrate
Formed on the surface of at least one pair of connection terminals.
A circuit board having a first high-frequency line provided therein;
And a dielectric substrate mounted on the surface of the second dielectric substrate
A high-frequency element, formed on the second dielectric substrate,
A second high-frequency line connected to the high-frequency element;
Having a connection terminal provided for connection to a circuit;
A number of high-frequency element packages, a third dielectric substrate,
A third high-frequency line formed on the third dielectric substrate;
Connection terminals provided for connection with the external circuit
A wiring board; and
Mounting a number of high-frequency element packages and the wiring board
A high-frequency module comprising:
L for all high frequency circuits₁All high frequency circuits in the circuit board
Length is L_TwoAnd L _Two/ L₁The length ratio represented by is 0.5
A high-frequency module characterized by the following. 6. The semiconductor device according to claim 5, wherein said first dielectric substrate is made of an insulating material containing an organic resin, and said second dielectric substrate and said third dielectric substrate are made of ceramics. High frequency module. 7. The semiconductor device according to claim 5, wherein a dielectric loss of said third dielectric substrate is smaller than that of said first dielectric substrate.
Or the high-frequency module according to claim 6. 8. The high-frequency module according to claim 5, wherein a high-frequency signal having a frequency of 10 GHz or more is transmitted to said high-frequency line.