JPH11261302A - Connection electrode structure and electronic device using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the connection electrode structure which can reduce the stray capacitance between a connection electrode and a ground electrode. SOLUTION: On a dielectric substrate 2 with a high dielectric constant, a bonding pad 5 as the connection electrode is formed and below the bonding pad 5 and its periphery, a columnar dielectric 15 with a low dielectric constant is provided to reduce electrostatic capacity C2 as the stray capacitance formed between the bonding pad 5 and ground electrode 3. Even when the in-use frequency becomes high, the impedance of the electrostatic capacity C2 does not become large so much to prevent electric characteristics of the bonding pad 5 from being degraded and further prevent degradation of electric characteristics of the whole circuit where the bonding pad 5 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection electrode structure and an electronic device using the same, and more particularly to a connection electrode structure of a component used in a high frequency band such as an RF stage of a mobile communication device and an electronic device using the same.

[0002]

2. Description of the Related Art With the development of mobile communication equipment in recent years, the frequency used has been increased to a higher frequency, and accordingly, problems specific to the high frequency have come to appear.

FIG. 5 shows a state in which two electronic devices having bonding pads as conventional connection electrodes are electrically connected. In FIG. 5, the electronic device 1 has a ground electrode 3 formed on almost the entirety of one main surface of a dielectric substrate 2 having a high dielectric constant, and a circuit (not shown) formed on the other main surface of the dielectric substrate 2. It is configured. A bonding pad 5 serving as a connection electrode is formed at an end of the other main surface of the dielectric substrate 2, and is connected to a circuit via a connection wiring 4. The electronic device 7 includes a ground electrode 9 on almost the entire one main surface of the dielectric substrate 8.
And a circuit (not shown) is formed on the other main surface of the dielectric substrate 8.
Is formed. A bonding pad 11 is formed at an end of the other main surface of the dielectric substrate 8, and is connected to a circuit via a connection wiring 10. The bonding pad 5 of the electronic device 1 and the bonding pad 11 of the electronic device 7 are connected via a wire 13.

[0004]

Here, FIG.
1 is a cross-sectional view of the electronic device 1 taken along line AA. As can be seen, a large ground electrode 3 is formed below the bonding pad 5 on the dielectric substrate 2. Moreover, a dielectric substrate 2 having a high dielectric constant exists between them. Therefore, a relatively large capacitance C1 is formed between the bonding pad 5 and the ground electrode 3 as a stray capacitance.

When the electronic device 1 is used at a low frequency, the capacitance C1 formed between the bonding pad 5 and the ground electrode 3 has a high impedance. . However, since the impedance of the capacitance C1 formed between the bonding pad 5 and the ground electrode 3 decreases as the operating frequency of the electronic device 1 increases, a signal flows from the bonding pad 5 to the ground electrode 3. As a result, there is a problem that the electrical characteristics of the electronic device 1 and the entire circuit using the electronic device 1 are adversely affected.

SUMMARY OF THE INVENTION An object of the present invention is to provide a connection electrode structure capable of reducing a stray capacitance between a connection electrode and a ground electrode, and an electronic device using the same. I do.

[0007]

In order to achieve the above object, a connection electrode structure according to the present invention comprises forming a connection electrode on a dielectric substrate having a high dielectric constant and forming the connection electrode on the dielectric substrate. A low dielectric constant dielectric is provided on at least one of the lower part and the lower part around the lower part.

Further, the connection electrode structure of the present invention is characterized in that the connection electrode is a bonding pad.

Further, an electronic device according to the present invention is characterized by using the above-mentioned connection electrode structure.

With this configuration, in the connection electrode structure of the present invention, the stray capacitance between the connection electrode and the ground electrode can be reduced.

Further, in the electronic device according to the present invention, it is possible to prevent the high-frequency characteristics from deteriorating due to the stray capacitance between the connection electrode and the ground electrode.

[0012]

FIG. 1 is a perspective view showing one embodiment of a connection electrode structure according to the present invention. Further, FIG. 2 shows a BB of FIG.
FIG. 1 and 2, the same or equivalent parts as those in FIGS. 5 and 6 are denoted by the same reference numerals, and description thereof will be omitted.

In FIGS. 1 and 2, a rectangular hole is formed in the bonding pad 5 serving as a connection electrode of the dielectric substrate 2 and a lower portion around the bonding pad 5 so as to penetrate the dielectric substrate 2, and a rectangular hole is formed in the rectangular hole. A quadrangular prism-shaped low dielectric constant dielectric 15 is provided so as to be filled. The height of the dielectric 15 having a low dielectric constant is formed to be the same as the thickness of the dielectric substrate 2. Therefore, the bonding pad 5, a part of the connection electrode 4, and a part of the ground electrode 3 are formed directly on the surface of the dielectric 15 having a low dielectric constant.

An example of a method for manufacturing the connection electrode structure thus configured will be described below. First, a square hole is previously formed in a high dielectric constant dielectric substrate at a position where a bonding pad is to be formed by using a mold or the like. Next, the square hole is filled with, for example, a resin that is a dielectric having a low dielectric constant and is cured. This may be a method of press-fitting a low-k dielectric material in the form of a quadrangular prism formed in advance in accordance with the square hole of the dielectric substrate. Then, a ground electrode, a bonding pad, a connection electrode and the like are formed on the dielectric substrate having a high dielectric constant and the dielectric having a low dielectric constant.

As described above, the low dielectric constant dielectric 15 is formed on the bonding pad 5 of the dielectric substrate 2 and the lower portion of the periphery thereof.
Is provided, a capacitance C2 as a stray capacitance formed between the bonding pad 5 and the ground electrode 3 is provided.
Can be made smaller than the capacitance C1 in the conventional example. As a result, even if the operating frequency increases, the impedance of the capacitance C2 does not decrease so much, and deterioration of the electrical characteristics of the bonding pad, that is, the connection electrode can be prevented.

FIG. 3 shows a sectional view of another embodiment of the connection electrode structure of the present invention. In FIG. 3, the same or equivalent parts as those in FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted.

Referring to FIG. 3, a rectangular hole which does not penetrate through the dielectric substrate 2 is formed in the bonding pad 5 of the dielectric substrate 2 and a lower portion of the periphery thereof. A dielectric 16 having a low dielectric constant whose height is smaller than the thickness of the dielectric substrate 2 is provided. Therefore, the bonding pad 5 and a part of the connection electrode 4 are formed directly on the surface of the dielectric 16.

It should be noted that the connection electrode structure configured as described above can be basically manufactured in the same manner as the connection electrode structure of FIG.

As described above, even if the dielectric 16 having a low dielectric constant does not penetrate through the dielectric substrate 2 and is formed only on a part of the dielectric substrate 2, the dielectric 16 is provided between the bonding pad 5 and the ground electrode 3. The formed capacitance C3 as a floating capacitance can be made smaller than the capacitance C1 in the conventional example. As a result, even if the operating frequency increases, the capacitance C3
Of the bonding pad, that is, the electrical characteristics of the connection electrode can be prevented from deteriorating.

In the embodiments shown in FIGS. 1 to 3, the low dielectric constant dielectric material is formed in the shape of a quadrangular prism. . In addition, the low dielectric constant dielectric is provided on the entire surface of the bonding pad and its lower part, but it is not always necessary to provide the dielectric on the bonding pad and a part of the lower part of the periphery of the bonding pad. It does not matter.

Further, the connection electrode is not limited to the bonding pad, and a similar effect can be obtained even if another connection electrode such as a soldering land is used.

FIG. 4 shows an embodiment of the electronic device of the present invention. In FIG. 4, an electronic device 20 includes a dielectric substrate 21 having a high dielectric constant, a ground electrode 22 formed on substantially the entirety of one main surface of the dielectric substrate 21, and a dielectric substrate 21 arranged in parallel with the other main surface of the dielectric substrate 21. Two formed microstrip lines 23 and 24, bonding pads 25 and 26 as connection electrodes formed at both ends of microstrip line 23, and bonding pads formed at both ends of microstrip line 24 27 and 2
8, bonding pads 25, 26 of the dielectric substrate 21,
It is composed of low dielectric constant dielectrics 25x, 26x, 27x, 28x provided at the lower part of 27 and 28 and the lower part of the periphery thereof. Here, the low dielectric constant dielectrics 25x, 26
x, 27x, and 28x are formed through the dielectric substrate 21 similarly to the dielectric 15 in FIG.

In the electronic device 20 configured as described above, the lengths of the microstrip lines 23 and 24 are formed to be about ４ of the wavelength at the target frequency, and are coupled to each other to form a directional coupler. Function.
Then, the bonding pads 25, 2
Low dielectric constant dielectrics 25x, 26 below 6, 27, 28
By providing x, 27x, and 28x, the stray capacitance formed between the bonding pad and the ground electrode is reduced.
It is possible to prevent the high-frequency characteristics of the electronic device 20, that is, the directional coupler, from deteriorating due to the stray capacitance between the ground electrodes 22 and 7, 28.

The directional coupler shown in FIG. 4 is one example, and the electronic device according to the present invention is provided with at least one of a lower portion of a connection electrode of a dielectric substrate having a high dielectric constant and a lower portion of the lower portion. It is not limited to a directional coupler as long as it has a low dielectric constant dielectric.

[0025]

According to the connection electrode structure of the present invention, a low dielectric constant dielectric is provided on at least one of the lower portion of the connection electrode of the dielectric substrate and the lower portion around the connection electrode, so that the connection electrode and the ground electrode can be separated. The stray capacitance formed therebetween can be reduced, and deterioration of the electrical characteristics of the connection electrode can be prevented. As a result, even in an electronic device configured using such a connection electrode structure, it is possible to prevent the electrical characteristics of the entire circuit from deteriorating at high frequencies.

[Brief description of the drawings]

FIG. 1 is a partially transparent perspective view showing one embodiment of the structure of a bonding pad of the present invention.

FIG. 2 is a cross-sectional view of the structure of the bonding pad of FIG. 1 taken along line BB.

FIG. 3 is a sectional view showing another embodiment of the structure of the bonding pad of the present invention.

FIG. 4 is a perspective view showing one embodiment of the electronic device of the present invention.

FIG. 5 is a perspective view showing a structure of a conventional bonding pad.

6 is a sectional view of the structure of the bonding pad shown in FIG. 5 taken along the line AA.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 2 ... Dielectric substrate 3 ... Ground electrode 4 ... Connection electrode 5 ... Bonding pad 15, 16 ... Low dielectric constant dielectric 20 ... Electronic device

Claims (3)

[Claims] 1. A connection electrode is formed on a dielectric substrate having a high dielectric constant, and a dielectric having a low dielectric constant is provided on at least one of a lower portion of the connection electrode and a lower portion of a periphery of the connection electrode on the dielectric substrate. A connection electrode structure. 2. The connection electrode structure according to claim 1, wherein said connection electrode is a bonding pad. 3. An electronic device using the connection electrode structure according to claim 1.