JPH09102433A - By-pass capacitor and its formation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress noise radiated from a print board and to stabilize signal waveform by forming a by-pass capacitor of a dielectric material which connects a power supply terminal and a ground terminal for coating and fixing. SOLUTION: A power supply terminal 2 and a ground terminal 4 are, in their vertical part, applied with high dielectric constant raw material 5 so that the power supply terminal 2 and the ground terminal 4 are joined together and fix-attached. The high dielectric constant raw material 5 acts as a by-pass capacitor. Relating to the high dielectric constant raw material 5, alumina and titanium oxide, etc., are mixed in resin, acting as a base. Thus the power supply terminal 2 and the ground terminal 4 are directly connected with the by-pass capacitor. So that, without influences of the inductance component of a power supply pattern 12 and a ground pattern 14 finely formed to avoid a signal line 13 and a through hole 17, etc., feeding to an IC package 1 is efficiently performed. And no capacitor components are required.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bypass capacitor for efficiently suppressing noise radiated from a printed circuit board and stabilizing a signal waveform.

[0002]

2. Description of the Related Art A bypass capacitor is used to suppress transmission / radiation noise from an electronic component such as an IC mounted on a printed circuit board from the printed circuit board.

That is, as shown in FIG. 4, a power supply terminal 102 of an electronic component 101 mounted on a printed circuit board 111.
By connecting a chip type or lead type capacitor component 115 (in FIG. 4, a chip type component is shown) between the power supply pattern 112 and the ground pattern 114, which are connected to the ground terminal 104 and the ground pattern 104, respectively, The capacitor component 115 is used as a bypass capacitor. Capacitor component 115 and each pattern 1
The connection with 02 and 104 is made by soldering.

[0004]

However, in the above-described conventional bypass capacitor, since wiring exists between the terminal of the electronic component and the capacitor component, depending on the wiring width and the surrounding wiring conditions, etc. As a result, an inductance exists between the electronic component and the capacitor component. The inductance is highly conductive in terms of direct current, but becomes more resistive as the frequency of alternating current becomes higher. And this works in the direction of weakening the high frequency coupling between the electronic component and the capacitor component. As a result, it is conceivable that the power supply to the power supply terminal and the ground terminal of the electronic component as the bypass capacitor is significantly hindered.

Particularly in an electronic component having a large number of terminals, as shown in FIG. 4, the power supply pattern 112 and the ground pattern 114 have wiring widths in order to avoid the signal lines 113 and the through holes 117 connected to the signal terminals 103. Becomes thin and is easily affected by the inductance component.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a bypass capacitor which eliminates an inductance with an electronic component and can efficiently feed power to the electronic component, and a method for forming the bypass capacitor.

[0007]

To achieve the above object, the bypass capacitor of the present invention is a bypass capacitor connected to a power supply terminal and a ground terminal of an electronic component mounted on a printed circuit board, wherein the power supply terminal and the ground terminal are connected to each other. It is characterized in that it is made of a dielectric material which is applied and fixed by connecting both to a ground terminal.

In this way, by connecting the power supply terminal and the ground terminal and applying the dielectric material to form the bypass capacitor, the bypass capacitor is directly connected to the electronic component, and the bypass capacitor is connected to the electronic component. There is no inductance.

As the dielectric material, for example, a material in which a dielectric substance is mixed with a resin base and the resin is in a paste state at the time of application can be used.

Further, in the case of an electronic component in which the signal terminal is arranged between the power supply terminal and the ground terminal, the signal terminal is made of a low dielectric constant material in order to prevent the influence of the dielectric material on the signal terminal. It is preferably coated. In this case, for example, resin is used as the low dielectric constant material.

A method of forming a bypass capacitor according to the present invention is a method of forming a bypass capacitor connected to a power supply terminal and a ground terminal of an electronic component mounted on a printed circuit board, wherein the power supply terminal and the ground terminal are connected to each other. It is characterized in that the two are connected to each other, a paste-like dielectric material is applied, the dielectric material is solidified, and the dielectric material is fixed to the power supply terminal and the ground terminal.

When applied to an electronic component in which a signal terminal is arranged between the power supply terminal and the ground terminal,
It is preferable to coat the signal terminals with a low dielectric constant material before applying the dielectric material.

As the dielectric material, a thermosetting resin,
A mixture of a dielectric material and a base made of a photocurable resin or a thermoplastic resin can be used.
When thermosetting resin is used as a base, the dielectric material is applied before soldering the electronic parts to the printed circuit board, and the heat applied in the solder melting process of the electronic parts is used to cure the dielectric material. Then, the dielectric material is fixed at the same time as soldering. When a photo-curable resin is used as a base, the dielectric material can be hardened by utilizing the light energy applied in the step of hardening the adhesive for fixing the chip component to the printed board. The material is fixed simultaneously with the fixing of the chip component. Further, in the case of using a thermoplastic resin as a base, the dielectric material is applied in a state where the thermoplastic resin is heated and melted, and then the dielectric material is cured by radiation cooling.

[0014]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic perspective view of an embodiment of the bypass capacitor of the present invention. In FIG. 1, an IC package 1 is mounted on a printed circuit board 11 as an electronic component. The IC package 1 has a power supply terminal 2, a ground terminal 4, and a signal terminal 3. The power supply terminal 2 and the ground terminal 4 are arranged with one signal terminal 3 interposed therebetween. These power supply terminal 2, ground terminal 4 and signal terminal 3
Are connected to the power supply pattern 12, the ground pattern 14, and the signal line 13 formed on the printed circuit board 1, respectively. The printed board 11 is also provided with a through hole 17, and the width of the power supply pattern 12 and the ground pattern 14 is narrow due to the influence of the through hole 17 and the signal line 13.

On the other hand, in the vertical portions of the power supply terminal 2 and the ground terminal 4, a high dielectric constant material 5 is applied and fixed by connecting the power supply terminal 2 and the ground terminal 4 together. Acts as a bypass capacitor. The high dielectric constant material 5 is based on resin and is mixed with a high dielectric constant substance such as alumina or titanium oxide.
When the high dielectric constant material 5 is applied, the resin is melted to form a paste, and the resin is cured after application,
The high dielectric constant material 5 is fixed. The base resin may be a thermosetting resin such as a phenol resin or an epoxy resin, a thermoplastic resin such as polysulfone, or a photocurable resin.

As described above, the high dielectric constant material 5 is applied between the power supply terminal 2 and the ground terminal 4, and the high dielectric constant material 5 constitutes a bypass capacitor. Will be directly connected to the ground terminal 4. Therefore, it is possible to efficiently supply power to the IC package 1 without being affected by the inductance components of the power source pattern 12 and the ground pattern 14 that are thinly formed to avoid the signal line 13, the through hole 17, and the like. Further, since the capacitor component is not required on the printed circuit board 1, the power supply pattern 12,
The degree of freedom in the pattern design of the ground pattern 14 and the signal line 13 is improved.

The dielectric material forming the bypass capacitor does not necessarily have to be the high dielectric constant material 5, but a material having a high dielectric constant is used because securing a large capacitance effectively works as the bypass capacitor. Is preferred. However, when the signal terminal 3 is arranged between the power supply terminal 2 and the ground terminal 4 as shown in FIG. 1, if a material having a high dielectric constant is used, the power supply terminal 2 and the ground terminal 4 are There is a case where a capacitive load is applied to the signal terminal 3 existing between the two, and the signal waveform becomes dull. Therefore, when it is not desired to apply a capacitive load to the signal terminal 3, the signal terminal 3 between the power supply terminal 2 and the ground terminal 4 is coated with the low dielectric constant material 6 in advance as shown in FIG. The high dielectric constant material 5 may be applied over the low dielectric constant material 6. As the low dielectric constant material 6, a thermosetting resin such as a Teflon resin or a polyimide resin, or a high heat resistant thermoplastic resin such as polysulfone can be used.

Next, a method of forming the bypass capacitor of the present invention will be described. First, a paste-like high dielectric constant material 5 is applied between the power supply terminal 2 and the ground terminal 4. As a method of applying the high dielectric constant material 5, for example, there is a method of using the dispenser 20 as shown in FIG. 2 and supplying the high dielectric constant material 5 between the power supply terminal 2 and the ground terminal 4 by the dispenser 20. By applying the high dielectric constant material 5 with the dispenser 20 in this manner, the high dielectric constant material 5 can be easily applied.

When the signal terminal 3 is present between the power supply terminal 2 and the ground terminal 4, the signal terminal 3 may have a low dielectric constant material as shown in FIG. 6 is coated, and the high dielectric constant material 5 is applied thereon. The coating of the low dielectric constant material 6 is performed by applying a paste in the same manner as the high dielectric constant material 5 and then solidifying.

Then, the resin serving as the base of the high dielectric constant material 5 is cured and fixed to the power supply terminal 2 and the ground terminal 4, but the curing method differs depending on the type of resin. For example, when a thermosetting resin base is used, I
Before soldering the C package 1 to the printed circuit board 11, the high dielectric constant material 5 is applied in advance, and the IC package 1
The base is cured using the heat applied in the soldering process. As a result, the high dielectric constant material 5 can be fixed at the same time when the IC package 1 is soldered, and the process can be simplified.

When a thermoplastic resin base is used, the high dielectric constant material 5 is applied in a state of being heated and melted, and the high dielectric constant material 5 is applied when the temperature returns to room temperature by radiative cooling after the application.
Is fixed. In this case, the application process of the high dielectric constant material 5 may be performed before or after the soldering of the IC package 1.

Further, when a photo-curable resin base is used, it is added in a step of curing an adhesive for fixing chip components (not shown) mounted on the printed board 11 before soldering. The high dielectric constant material 5 is cured using light energy such as ultraviolet rays.

In this way, by coating the high dielectric constant material 5 between the power supply terminal 2 and the ground terminal 4 of the IC package 1 and fixing them, the bypass directly connected to the power supply terminal 2 and the ground terminal 4 is obtained. Capacitors are easily obtained.

In the embodiment described above, the high dielectric constant material 5 is applied to the vertical portions of the power supply terminal 2 and the ground terminal 4, but the application position is not particularly limited.
Some of the examples are shown in FIG. The position indicated by reference numeral 5a is the same as that described in FIG. The position indicated by 5b is the root portion of the terminal, and the position indicated by 5c is the tip portion of the terminal. In this way, the effect is the same regardless of where the high dielectric constant material 5 is applied. Therefore, the shape of the IC package 1 and the printed circuit board 1 of the electronic components around it
Considering the layout of No. 1, the high dielectric constant material 5 may be applied at the position where it is most easily applied.

[0026]

Since the present invention is configured as described above, it has the following effects.

Since the bypass capacitor of the present invention is made of a dielectric material applied by connecting the power supply terminal and the ground terminal of the electronic component, the inductance between the electronic component and the electronic component is eliminated, and power is supplied to the electronic component. It can be done efficiently. Furthermore, it is not necessary to provide a bypass capacitor on the printed board, and the space for effective use of the printed board is increased, so that the degree of freedom in pattern design of the signal lines and the like can be improved. Further, when applied to an electronic component in which a signal terminal is arranged between a power supply terminal and a ground terminal, by covering the signal terminal with a low dielectric constant material, it is possible to prevent blunting of the signal waveform due to the influence of the bypass capacitor. be able to.

According to the method of forming a bypass capacitor of the present invention, a bypass capacitor having the above effect can be obtained very simply by connecting the power supply terminal and the ground terminal of the electronic component and applying and fixing the dielectric material. .

In particular, when a thermosetting resin base mixed with a dielectric substance is used as the dielectric material, the heat applied in the step of soldering the electronic component to the printed circuit board is utilized, The applied dielectric material can be fixed at the same time as soldering. Further, when a mixture of a dielectric substance and a base of a photo-curable resin is used as the dielectric material, the light energy applied to cure the adhesive for fixing the chip component to the printed board is Utilizing this, the applied dielectric material can be fixed simultaneously with the fixing of the chip component.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an embodiment of a bypass capacitor of the present invention.

FIG. 2 is a diagram for explaining a method of applying a dielectric material in the bypass capacitor shown in FIG.

FIG. 3 is a diagram showing various examples of formation positions of a bypass capacitor of the present invention.

FIG. 4 is a schematic perspective view showing a configuration of a conventional bypass capacitor.

[Explanation of symbols]

 1 IC Package 2 Power Terminal 3 Signal Terminal 4 Ground Terminal 5 High Dielectric Material 6 Low Dielectric Material 11 Printed Circuit Board 12 Power Pattern 13 Signal Line 14 Ground Pattern 17 Through Hole 20 Dispenser

Claims (9)

[Claims] 1. A bypass capacitor connected to a power supply terminal and a ground terminal of an electronic component mounted on a printed circuit board, wherein a dielectric material is applied and fixed by connecting the power supply terminal and the ground terminal to each other. By-pass capacitor. 2. The bypass capacitor according to claim 1, wherein the dielectric material is a base made of resin mixed with a dielectric substance, and the resin is in a paste state when applied. 3. The electronic component according to claim 1, wherein a signal terminal is arranged between the power supply terminal and the ground terminal, and the signal terminal is covered with a low dielectric constant material. Bypass capacitor. 4. The low dielectric constant material is a resin.
Bypass capacitor described in. 5. A method of forming a bypass capacitor connected to a power supply terminal and a ground terminal of an electronic component mounted on a printed circuit board, wherein the power supply terminal and the ground terminal are connected to each other in a paste form. A method of forming a bypass capacitor, characterized by applying a dielectric material, solidifying the dielectric material, and fixing the dielectric material to the power supply terminal and the ground terminal. 6. The electronic component is one in which one or a plurality of signal terminals are arranged between the power supply terminal and the ground terminal, and the signal terminal is preliminarily applied before applying the dielectric material. The method for forming a bypass capacitor according to claim 5, wherein the material is covered with a low dielectric constant material. 7. As the dielectric material, a mixture of a dielectric substance and a base made of a thermosetting resin is used, and the dielectric material is applied before the solder of the electronic component is melted to the printed circuit board. 7. The method for forming a bypass capacitor according to claim 5, wherein the dielectric material is hardened by utilizing heat applied in a solder melting step of the electronic component. 8. The dielectric material is a base made of a photocurable resin mixed with a dielectric substance, and is added in a step of curing an adhesive for fixing a chip component to the printed board. 7. The method for forming a bypass capacitor according to claim 5, wherein the dielectric material is cured by using the generated light energy. 9. As the dielectric material, a base made of a thermoplastic resin mixed with a dielectric substance is used, and the dielectric material is applied in a state where the thermoplastic resin is heated and melted. The method for forming a bypass capacitor according to claim 5, wherein the dielectric material is cured by radiation cooling.