JP3244677B2 - Electronic circuit unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface mounting type electronic circuit unit which is suitable for miniaturization. SOLUTION: In this electronic circuit unit, circuit elements containing capacitors C1-C7, resistors R1-R3, inductance elements L1-L3, etc., and a conductive pattern P connected to the circuit elements are formed on an alumina substrate 1 in the form of thin films, and a bare semiconductor chip of a diode D1 and a transistor Tr1 is wire-bonded to the connecting lands of the pattern P. In addition, an inductance element composed of a pair of conducting paths S1 and S2 faced to each other at a prescribed interval is formed on the substrate 1 in the form of thin films so as to constitute an unbalanced-to-balanced conversion circuit of the paths S1 and S2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type electronic circuit unit, and more particularly to an electronic circuit unit provided with an unbalanced / balanced conversion circuit.

[0002]

2. Description of the Related Art In general, a surface mount type electronic circuit unit of this type solders a chip component such as a resistor and a capacitor and a semiconductor component such as a transistor to solder lands of a conductive pattern provided on a substrate. The circuit components are schematically configured to be covered by a shield cover. An end face electrode is provided on a side surface of the board, and when the electronic circuit unit is surface-mounted on the mother board, the end face electrode is soldered to a solder land of the mother board.

Heretofore, there has been known an electronic circuit unit having a schematic configuration in which an unbalanced / balanced conversion circuit for converting an unbalanced signal into a balanced signal and outputting the signal is mounted. Normally, this unbalanced / balanced conversion circuit is composed of a surface mount component in which a pair of conductive paths are juxtaposed on a flat dielectric substrate, and electrodes provided on the dielectric substrate are soldered to conductive patterns on a multilayer substrate. Thus, the unbalanced signal can be converted into a balanced signal by the unbalanced / balanced conversion circuit and output.

[0004]

In recent years, techniques for miniaturizing circuit components such as chip components and semiconductor components have been remarkably advanced. For example, ultra-small chip resistors or chips having an outer dimension of about 0.6 × 0.3 mm have been developed. Capacitors have also been put to practical use. Therefore, even in the above-mentioned conventional electronic circuit unit, if such ultra-small circuit components are used and these circuit components are mounted on a substrate with the pitch between the components being narrowed, the electronic circuit unit can be reduced to some extent. Can be reduced in size. However, miniaturization of circuit components such as chip components and semiconductor components is limited, and moreover,
When mounting a large number of circuit components on a board, it is necessary to prevent the soldered portions of each circuit component from being short-circuited.Therefore, there is a limit in narrowing the pitch between components, and these are limitations of the electronic circuit unit. This was a major factor hindering further miniaturization. Further, since the unbalanced / balanced conversion circuit is constituted by surface-mounted components, and a pair of conductive paths are juxtaposed over a predetermined length or more in order to secure a desired degree of coupling, the surface-mounting circuit is required. Since the components are relatively large components, the limited mounting space on the board is narrowed by the surface mounting components for the unbalanced / balanced conversion circuit, which also hinders miniaturization of the electronic circuit unit. Had been.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances of the prior art, and has as its object to provide a surface mount type electronic circuit unit suitable for downsizing.

[0006]

In order to achieve the above object, in an electronic circuit unit of the present invention, a circuit element including a capacitor and a resistor and a conductive pattern connected to the circuit element are formed on an alumina substrate by a thin film. Forming and mounting a semiconductor bare chip on the alumina substrate, wire bonding the semiconductor bare chip to the conductive pattern, and an inductance element including a pair of conductive paths facing each other at a predetermined interval on the alumina substrate. Is formed as a thin film, and the unbalanced /
A balanced conversion circuit was constructed.

According to such a structure, the circuit element including the capacitor and the resistor is formed with high precision by using a thin film technique, and the semiconductor element is formed by wire bonding a bare chip. Thus, a surface-mounted electronic circuit unit suitable for miniaturization can be realized in which circuit components are mounted at high density.
Furthermore, since an inductance element composed of a pair of conductive paths is formed as a thin film on the alumina substrate, and an unbalanced / balanced conversion circuit is formed by the pair of conductive paths of the inductance element, a gap between the two conductive paths is narrowed to a desired value. The degree of coupling can be ensured, which is also advantageous for downsizing the electronic circuit unit.

In the above configuration, when a pair of conductive paths constituting the unbalanced / balanced conversion circuit are formed on the same surface of the alumina substrate, the gap between the two conductive paths can be narrowed to increase the degree of coupling. Further, when the pair of conductive paths is laminated on the alumina substrate via an insulator, the installation space of both conductive paths on the alumina substrate can be further reduced. Further, the pair of conductive paths is preferably formed in a spiral or zigzag shape.

[0009]

1 is a perspective view of an electronic circuit unit, FIG. 2 is a plan view of an alumina substrate showing a circuit configuration layout, and FIG. 4 is a back view of the alumina substrate, FIG. 4 is an explanatory view of a circuit configuration, FIG. 5 is a perspective view showing an end face electrode, FIG. 6 is a sectional view of the end face electrode, FIG. 7 is an explanatory view showing a relationship between a semiconductor bare chip and a connection land. FIG. 8 is an explanatory diagram illustrating a manufacturing process of the electronic circuit unit.

This embodiment is an example of application to a frequency-tuned booster amplifier. This frequency-tuned booster amplifier is illustrated for improving the reception performance (particularly, reception sensitivity and anti-jamming characteristics) of a portable television device. It is used in combination with a UHF tuner, and has a function of selecting a TV signal of a desired frequency and amplifying the selected TV signal and inputting the amplified signal to the UHF tuner.

FIG. 1 shows an appearance of such a frequency tuning type booster amplifier (electronic circuit unit). As shown in FIG. 1, the frequency tuning type booster amplifier includes an alumina substrate 1 on which circuit components described later are mounted, and It is composed of a shield cover 2 attached to the alumina substrate 1 and is a surface mount component to be soldered to a mother substrate (not shown). The alumina substrate 1 is formed in a rectangular flat plate shape. The alumina substrate 1 is obtained by cutting a large-sized substrate into strip-shaped divided pieces, and further subdividing the divided pieces. The shield cover 2 is formed by bending a metal plate into a box shape, and the circuit components on the alumina substrate 1 are the shield cover 2.
Covered by

As shown in FIG. 2, circuit components and conductive patterns for connecting them are provided on the front surface of the alumina substrate 1, and as shown in FIG. A conductive pattern as an electrode is provided. The frequency tuning type booster amplifier according to the present embodiment has a tuning circuit and an amplifier circuit for selecting and amplifying a TV signal, and has a circuit configuration as shown in FIG.
Each circuit component shown in FIG. 2 is denoted by a reference numeral corresponding to the circuit diagram of FIG. However, FIG. 4 shows an example of the circuit configuration, and the present invention can be applied to an electronic circuit unit having another circuit configuration.

As shown in FIG. 4, the frequency tuning type booster amplifier includes capacitors C1 to C7, resistors R1 to R3, inductance elements L1 to L3, a diode D1, a transistor T1 which are circuit components of a tuning circuit and an amplifier circuit.
r 1, conductive paths S 1, S 2, etc., and these circuit components and the conductive patterns connecting them are provided on the surface of the alumina substrate 1. This conductive pattern is formed, for example, of Cr, Cu, or the like by using a thin film technique such as sputtering, and is denoted by a symbol P in FIG.

The circuit configuration of the frequency tuning type booster amplifier will be briefly described. In order to select and amplify a TV signal of a desired frequency, a tuning circuit including inductance elements L2 and L3, capacitors C3 and C4 and a diode D1; It comprises an amplifier circuit comprising a transistor Tr1, its peripheral circuit elements (resistors R1 to R3, capacitor C6) and an unbalanced / balanced conversion element T. TV signals of a plurality of frequencies are input to the tuning circuit via the capacitor C1. Since the tuning frequency (resonance frequency) of the tuning circuit is variable by controlling the voltage (Vctl) applied to the cathode of the diode D1, by matching the frequency of the desired TV signal, only the desired TV signal is selected and the capacitor C5 is selected. Through the transistor T of the amplifier circuit
Input to the base of r1. A bias voltage is applied to the base bias voltage dividing resistors R1 and R2 at the base of the transistor Tr1, and the collector current (≒ emitter current) of the transistor Tr1 is set by the resistance value of the emitter resistor R3. The TV signal amplified by the transistor Tr1 is output from a collector, and the collector is provided with an unbalanced / balanced conversion element T. The unbalanced / balanced conversion element T is constituted by an inductance element composed of a pair of conductive paths S1 and S2 coupled to each other.
2 output a balanced TV signal from both ends of the UHF
Input to the tuner.

As shown in FIG. 2, the ground electrode (GND) and the input electrodes (Vcc, Vct)
1, RFin) and an output electrode (RFout), which are formed by a part of the conductive pattern P. The ground electrode, the input electrode, and the output electrode are formed only on the two long sides facing each other of the rectangular alumina substrate 1, and are not formed on the other two short sides facing each other. That is, GND electrodes are formed at both corners (corners) on one long side of the alumina substrate 1, and a Vcc electrode, an RFin electrode, and a Vctl electrode are formed between these GND electrodes. In addition, GND electrodes are formed at both corners on the other long side of the alumina substrate 1 and three places near the two corners, and two RFout electrodes are formed between these GND electrodes. As will be described later, the two long sides of the alumina substrate 1 correspond to the dividing lines when the large-sized substrate is cut into strip-shaped divided pieces, and the two short sides of the alumina substrate 1 further connect the divided pieces. It corresponds to the division line when subdividing.

On the other hand, as shown in FIG.
The conductive pattern P1 (rear electrode) provided on the back surface of each of the ground electrodes (GND) and the input electrodes (Vcc, V
ctl, RFin) and the output electrode (RFout), and both are electrically connected via the end face electrode 3 as shown in FIGS. The end face electrode 3 is obtained by sequentially laminating a Ni base plating layer and an Au plating layer on an Ag thick film layer, and the lowermost Ag thick film layer is made of Ag containing no glass component.
After the paste is formed into a thick film, the paste is made of a low-temperature fired material fired at about 200 ° C. The intermediate Ni plating layer facilitates the adhesion of the Au plating layer, and the uppermost Au plating layer is formed when the end face electrode 3 is soldered to a solder land of a mother substrate (not shown). This is for preventing the lower layer Ag from depositing on the solder. Then, in a completed electronic circuit unit in which the shield cover 2 is attached to the alumina substrate 1, the leg pieces 2a formed by bending the side surfaces of the shield cover 2 are soldered to the end face electrodes 3 which are electrically connected to the ground electrode (GND). The shield cover 2 is grounded at the four corners of the alumina substrate 1.

Among the above-described circuit components, the capacitors C1 to C7 are formed by laminating an upper electrode on a lower electrode via a dielectric film such as SiO ₂ , and these are formed as thin films by sputtering or the like. ing. C on the surface of the upper electrode
A u layer is provided, and the Q of the resonance circuit is increased by the Cu layer. The lower electrode and the upper electrode of the capacitors C1 to C7 are connected to the conductive pattern P, and as shown in FIG. 2, the conductive pattern P between the capacitor C7 and the Vcc electrode, the conductive pattern P between the capacitor C7 and the RFout electrode, Each of the conductive patterns P between the C2 and Vctl electrodes is provided with a proximity part (air gap) G for discharge. The proximity portion G is constituted by a pair of protrusions provided on each of the conductive patterns P arranged side by side facing each other, and the tips of both protrusions face each other with a predetermined gap. . In this case, the conductive pattern P
In addition, since the dimensional accuracy of the gate electrode and the GND electrode is improved by the thin film technology, the gap dimension of the adjacent portion G can be narrowed, and discharge at a low voltage is possible. Further, among the capacitors C1 to C7, the capacitors C1 and C3 to C5
Is formed in a simple square shape, but the capacitors C2 and C7 are formed in different shapes by combining two or more square shapes. That is, the capacitor C2 has a concave shape in which two rectangles protrude from one side of one rectangle, and the capacitor C7 has a shape in which three rectangles are successively shifted in the long side direction. These capacitors C2 and C7 are grounding capacitors that require a relatively large capacitance value. When the grounding capacitors C2 and C7 are formed in such irregular shapes, the limited space on the alumina substrate 1 is effectively used, A capacitor having a desired capacitance value can be mounted at a high density.

Further, among the capacitors C1 to C7,
The capacitor C6 is composed of two grounding capacitors having different sizes, and both are connected in parallel via a pair of conductive patterns P separated from each other. That is, as shown in FIG. 2, each one electrode portion of both grounding capacitors C6 is connected to the grounding conductive pattern P connected to the GND electrode, while each other electrode portion of both grounding capacitors C6 is The transistor Tr1 is connected to the connection land SL of the transistor Tr1 via two conductive patterns P separated from each other. As is clear from FIG. 4, the capacitor C6 is provided between the emitter of the transistor Tr1 and the ground, and the connection land SL is a place where the emitter electrode of the transistor Tr1 is wire-bonded.
The capacitance value of the capacitor C6 is set by two grounding capacitors connected in parallel via the conductive patterns P separated from each other. Accordingly, the inductance of the entire conductive pattern P from the emitter electrode of the transistor Tr1 to the ground via the capacitor C6 is reduced, and the grounding effect of the connection land SL by the grounding capacitor C6 is improved. Since the parasitic oscillation frequency caused by the capacitor C6 and each conductive pattern P increases, the parasitic oscillation can be eliminated by setting this frequency to be equal to or higher than the operating point frequency of the transistor Tr1.

The resistors R1 to R3 are each formed by forming a resistive film such as TaSiO ₂ by using a thin film technique such as sputtering, and a dielectric film such as SiO ₂ is provided on the surface thereof as required. As shown in FIG. 2, three resistors R1 to R3
Among them, the resistors R1 and R2 are formed as thin films side by side at positions close to each other on the alumina substrate 1, and the remaining resistor R3 is formed as a thin film at positions away from the resistors R1 and R2.
As described above, since the resistors R1 and R2 are formed as thin films at positions close to each other, even if the resistance values of the resistors R1 and R2 vary from a desired value, the ratio of the variation of the entire resistors R1 and R2 is reduced. Can be the same. As is clear from FIG. 4, the resistors R1 and R2 are voltage dividing resistors for the base bias of the transistor Tr1, and R1 / (R1 + R2)
A voltage of × Vcc is applied to the base of the transistor Tr1. Here, a resistor R which is a voltage dividing resistor for base bias is used.
As described above, the ratio of the variation between the resistors R1 and R2 is always the same, so that it is not necessary to trim the resistance values of the resistors R1 and R2. On the other hand, the resistor R3 is an emitter resistor of the transistor Tr1, and a current flows from the Vcc electrode to the collector and the emitter of the transistor Tr1, and is further grounded through the resistor R3. Here, each of the resistors R1 to R
3, the emitter R3 has the largest contribution to the amplification of the transistor Tr1. Therefore, only the resistor R3 is trimmed to adjust the output so that the current value is constant.

Incidentally, as shown in FIG.
In the case of a circuit configuration in which another transistor Tr2 is connected in series to r1, resistors R1, R2, and R4, which are voltage dividing resistors for base bias of both transistors Tr1 and Tr2, are formed as thin films at positions close to each other on the alumina substrate 1. If this is the case, trimming of the resistance values for these resistors R1, R2, R4 becomes unnecessary. Therefore, also in this case, the current value of both transistors Tr1 and Tr2 can be set by trimming only the resistor R3 which is the emitter resistor.

The inductance elements L1 to L3 and the conductive paths S1 and S2 are formed of Cr, Cu, or the like by using a thin film technique such as sputtering, and are connected to the conductive pattern P. A Cu layer is provided on the surface of each of the inductance elements L1 to L3, and the Cu layer enhances the Q of the resonance circuit. Each of the inductance elements L1 and L2 is formed in a rectangular spiral shape, and one end of each is wire-bonded to a Vctl electrode or a conductive pattern P for grounding. The inductance element L2 is for setting a resonance frequency for setting an approximate resonance frequency, and the inductance element L3 is for setting the inductance element L.
2 is continuous with the other end. The inductance element L3 is an adjustment conductive pattern for adjusting the resonance frequency,
As shown by the broken line in FIG. 2, the inductance element L3
Are increased to adjust the resonance frequency. In this case, the trimmed inductance element L3
Is the inductance element L2 for setting the resonance frequency.
, The characteristic impedances of the inductance element L2 and the inductance element L3 do not change, and oscillation with a good C / N ratio can be obtained.

As described above, the unbalanced / balanced conversion element T
Is formed by an inductance element composed of a pair of conductive paths S1 and S2 coupled to each other.
S2 is formed on the alumina substrate 1 as a thin film. These conductive paths S1 and S2 are spirally formed on the alumina substrate 1 so as to face each other with a predetermined gap therebetween. Both ends of one conductive path S1 are connected to the collector electrode of the transistor Tr1 and the capacitor C7. The other end of the other conductive path S2 is connected to a pair of RFout electrodes. In this case, since the dimensional accuracy of the conductive paths S1 and S2 formed as a thin film is high, both the conductive paths S1 and S2
A desired coupling degree can be ensured by narrowing the gap between them, and a small unbalanced / balanced conversion element T can be provided in a limited space on the alumina substrate 1. In addition,
As shown in FIG. 10, a pair of conductive paths S <b> 1 and S <b> 2 facing each other via a predetermined gap may be formed on the alumina substrate 1 in a zigzag shape.

The diode D1 and the transistor Tr
Reference numeral 1 denotes a semiconductor bare chip mounted on a connection land of a conductive pattern P formed as a thin film on an alumina substrate 1, and the semiconductor bare chip is wire-bonded to the conductive pattern P. That is, as shown in FIG. 2, the semiconductor bare chip of the diode D1 has a square shape, and one electrode provided on the lower surface thereof is fixed to the connection land using a conductive adhesive such as cream solder or conductive paste. The other electrode provided on the upper surface of the semiconductor bare chip is wire-bonded to a predetermined portion of the conductive pattern P.
The semiconductor bare chip of the transistor Tr1 also has a square shape, a collector electrode provided on the lower surface thereof is fixed to a connection land using a conductive adhesive, and a base electrode and an emitter electrode are wire-bonded to predetermined portions of the conductive pattern P. Have been. Similarly to the end face electrode 3 described above, a Ni base plating layer and an Au plating layer are sequentially laminated on these connection lands. Here, as shown in FIG. 7A or 7B, the area of the connection land 5 is formed to be smaller than the lower area of the semiconductor bare chip 4, and by adopting such a configuration, the semiconductor bare chip 4
, A reservoir of the conductive adhesive is secured below the semiconductor chip 4, so that an accident that the conductive adhesive protrudes from the outer shape of the semiconductor bare chip 4 and short-circuits with the surrounding conductive pattern P can be prevented beforehand. Further, an opening 5a is provided in the connection land 5, and since an excess of the conductive adhesive is accumulated in the opening 5a, it is possible to more reliably prevent the conductive adhesive from protruding. .

Next, the manufacturing process of the electronic circuit unit configured as described above will be described mainly with reference to FIG.

First, as shown in FIG. 8A, after sputtering the whole surface of the alumina substrate 1 with TaSiO ₂ or the like,
This is etched into a desired shape to form the resistive film 6, thereby forming a portion corresponding to the resistors R1 to R3. Next, as shown in FIG. 8B, Cr or Cu or the like is sputtered from above the resistive film 6, and is etched into a desired shape to form the lower electrode 7, and then as shown in FIG. As described above, SiO ₂ or the like is sputtered from above the lower electrode 7 and is etched into a desired shape to form the dielectric film 8. Next, as shown in FIG. 8D, after sputtering Cr, Cu, or the like from above the dielectric film 8, this is etched into a desired shape to form the upper electrode 9. As a result, the conductive pattern P and the inductance elements L1 to L3 and the conductive paths S1,
A portion corresponding to S2 is formed, and a laminate of the lower electrode 7, the dielectric film 8, and the upper electrode 9 forms the capacitors C1 to C1.
A portion corresponding to C7 is configured. Next, after a Cu layer is formed on the surfaces of the portions corresponding to the inductance elements L1 to L3, the conductive paths S1 and S2, and the capacitors C1 to C7 by plating or thin film technology, as shown in FIG. The protective film 10 is formed in a portion excluding P. Next, as shown in FIG. 8 (f), after sputtering Cr, Cu, or the like on the entire back surface of the alumina substrate 1, this is etched into a desired shape to form the back electrode 11, whereby the conductive material on the back surface side is formed. A portion corresponding to the pattern P1 is configured.

The steps shown in FIGS. 8A to 8F described above are performed on a large-sized substrate made of an alumina material in which divisional grooves extending in a grid pattern are cut in the vertical and horizontal directions. The steps shown in FIGS. 8G to 8J are performed on the strip-shaped divided pieces obtained by cutting the large-sized substrate along the dividing grooves in one direction.

That is, after cutting the large-sized substrate into strip-shaped divided pieces, as shown in FIG. 8 (g), a thick Ag layer 12 is formed on both end faces of the alumina substrate 1, which are cut surfaces of the divided pieces. The grounding electrode (GND) and the input electrode (V) of the conductive patterns P, P1 provided on the front and back surfaces of the alumina substrate 1 are formed.
(cc, Vctl, RFin) and the output electrode (RFout) are conducted through the Ag layer 12. The Ag layer 12 corresponds to the Ag thick film layer of the end face electrode 3 described above, and is a low-temperature fired material made of an Ag paste containing no glass component. Note that the thick film forming step of the Ag layer 12 can be performed on one strip-shaped divided piece. However, when a plurality of divided pieces are overlapped with a slight gap therebetween, Ag can be obtained. The layer 12 can be simultaneously formed into a thick film on a plurality of divided pieces, which is suitable for mass production. Next, on each surface of the connection land on which the Ag layer 12 and the semiconductor bare chip are mounted, a Ni underlayer and an A
After the u layers are sequentially plated, as shown in FIG. 8 (h), the diode D1 and the semiconductor bare chip of the transistor Tr1 are fixed on each connection land using a conductive adhesive such as cream solder or conductive paste. In this case, as described above, since the area of the connection land is formed smaller than the lower area of the semiconductor bare chip, the conductive adhesive is prevented from protruding from the semiconductor bare chip, and the conductive adhesive is applied to the semiconductor bare chip. Undesired short circuit with the surrounding conductive pattern P is prevented. Next, as shown in FIG. 8 (i), after each semiconductor bare chip is wire-bonded to a predetermined portion of the conductive pattern P, as shown in FIG. 8 (j), a resistor R3 which is an emitter resistor is trimmed and output. At the same time, the resonance frequency is adjusted by trimming the inductance element L3, which is an adjustment conductive pattern.
In this case, the adjustment of the resonance frequency is performed in the state of the strip-shaped divided pieces before being divided into the individual alumina substrates 1, and the grounding electrodes (GND) are provided at the corners of each alumina substrate 1. Electrodes (Vcc, Vctl, RFin) and output electrodes (RFou
The ground electrode (GND) is always located during t), so that the adjustment of the resonance frequency does not adversely affect the circuit of the adjacent alumina substrate 1.

Next, a shield cover 2 is attached to each of the alumina substrates 1 of the strip-shaped divided pieces.
By soldering the leg piece 2a to the end face electrode 3 conducting to the ground electrode (GND), the divided piece is subdivided into the individual alumina substrates 1 along the other divided groove, as shown in FIG. A simple electronic circuit unit is obtained.

According to the electronic circuit unit according to the above-described embodiment, the capacitors C1 to C7, the resistors R1 to R3, the inductance elements L1 to L3, and the conductive paths S1 and S2 are formed on the alumina substrate 1. A circuit element and a conductive pattern P connected to these circuit elements are formed as a thin film, a diode D1 and a semiconductor bare chip of a transistor Tr1 are wire-bonded on the alumina substrate 1, and a conductive pattern is formed on the side surface of the alumina substrate 1. Since the end face electrode 3 connected to the grounding electrode and the input / output electrode is provided, required circuit components can be mounted on the alumina substrate 1 at a high density using thin film technology and semiconductor device wire bonding. A surface-mount type electronic circuit unit suitable for downsizing can be realized. A pair of conductive paths S1, S2 formed as a thin film on the alumina substrate 1
Since the unbalanced / balanced conversion circuit is formed by this, the gap between the two conductive paths S1 and S2 can be narrowed to secure a desired degree of coupling, which is also advantageous for miniaturization of the electronic circuit unit.

In the above-described embodiment, the case where the pair of conductive paths S1 and S2 constituting the unbalanced / balanced conversion circuit are formed as a thin film on the same surface of the alumina substrate 1 has been described. Similarly to the configuration, a pair of conductive paths S1 and S2 can be laminated on the alumina substrate 1 with an insulator such as SiO ₂ interposed therebetween. The installation space can be further reduced.

[0031]

The present invention is embodied in the form described above and has the following effects.

A circuit element including a capacitor and a resistor and a conductive pattern are formed on an alumina substrate in a thin film.
A bare chip of a semiconductor element is wire-bonded on this alumina substrate, and an inductance element composed of a pair of conductive paths is formed as a thin film on the alumina substrate to form an unbalanced / unbalanced chip.
Since the balanced conversion circuit is formed, not only can the required circuit components be mounted on the alumina substrate with high density, but also the gap between both conductive paths forming the unbalanced / balanced conversion circuit can be narrowed to achieve a desired degree of coupling. , And the size of the electronic circuit unit can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of an electronic circuit unit according to an embodiment of the present invention.

FIG. 2 is a plan view of an alumina substrate showing a circuit configuration layout.

FIG. 3 is a rear view of the alumina substrate.

FIG. 4 is an explanatory diagram of a circuit configuration.

FIG. 5 is a perspective view showing an end face electrode.

FIG. 6 is a sectional view of an end face electrode.

FIG. 7 is an explanatory diagram showing a relationship between a semiconductor bare chip and connection lands.

FIG. 8 is an explanatory diagram illustrating a manufacturing process of the electronic circuit unit.

FIG. 9 is an explanatory diagram of another circuit configuration.

FIG. 10 is a plan view of an alumina substrate showing another circuit configuration layout.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Alumina substrate 2 Shield cover 3 End face electrode 4 Semiconductor bare chip 5 Connection land 5a Opening 6 Resistive film 7 Lower electrode 8 Dielectric film 9 Upper electrode 10 Protective film 11 Back electrode 12 Ag layer C1-C7 Capacitors R1-R3 Resistance L1-L3 Inductance element Tr1, Tr2 Transistor S1, S2 Conductive path P, P1 Conductive pattern SL Connection land

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-51179 (JP, A) JP-A-7-106811 (JP, A) JP-A-5-251629 (JP, A) JP-A-5-251629 36857 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 25/00

Claims (4)

(57) [Claims] 1. A circuit element including a capacitor and a resistor and a conductive pattern connected to these circuit elements are formed in a thin film on an alumina substrate, and a semiconductor bare chip is mounted on the alumina substrate. The method is characterized in that an inductance element composed of a pair of conductive paths facing each other at a predetermined interval is formed on the alumina substrate by wire bonding to a pattern, and an unbalanced / balanced conversion circuit is formed by the inductance element. Electronic circuit unit. 2. The electronic circuit unit according to claim 1, wherein said pair of conductive paths are formed on the same surface of said alumina substrate. 3. The electronic circuit unit according to claim 1, wherein the pair of conductive paths are laminated on the alumina substrate via an insulator. 4. The electronic circuit unit according to claim 1, wherein the pair of conductive paths are formed in a spiral shape or a zigzag shape.