JP2002134850A - Circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board which has an easily and cheaply formable structure coping with surge voltages of incoming surges, etc., and electrostatic charges and is usable continuously as it is even after coping with the incoming surges, etc. SOLUTION: The circuit board 1 has electronic components mounted conductively to patterned conductor wirings 3 on an insulation board 2 and a discharge gap type surge absorber 4. The absorber 4 is composed of through- holes 20 which pierce the thickness of the board 2 and locate on dividing regions between input terminals or output terminals 31 and the electronic components on the conductor wirings 3, first conductor pieces 41 conductively connecting the conductor wirings 3 at the dividing regions and second conductor pieces 42 conductive to grounding terminals on the wirings 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board provided with a surge absorber for preventing malfunction or breakage of electronic components due to surge voltage or static electricity.

[0002]

2. Description of the Related Art In a circuit board on which various electronic components are mounted, an unnecessary voltage is applied to a circuit due to an external surge such as a lightning surge, a surge generated when a switch is opened and closed, and static electricity charged in the circuit. In such a case, the electronic components may malfunction or be damaged. For this reason, conventionally, a fuse is provided in a circuit, or a surge absorber such as a varistor is provided.

[0003] Here, the varistor refers to a resistance having a voltage dependency of which the resistance value changes according to the value of an applied voltage. The varistor substantially changes the resistance value according to the voltage value to substantially reduce the current value flowing through the circuit. It should be kept constant.

[0004]

However, since the fuse is blown when an excessive current flows, once the fuse is melted and the circuit is opened, a fuse must be provided again. Alternatively, the entire circuit board needs to be replaced. As described above, when the fuse is provided, there is a disadvantage that the circuit board cannot be repeatedly used as it is.

On the other hand, a varistor responds to an external surge or the like by a change in resistance value and does not blow like a fuse. It can be used as it is without replacement. On the other hand, the varistor has a drawback that the structure is complicated and expensive.

The present invention has been conceived in view of such circumstances, and is capable of responding to surge voltages such as external surges and static electricity by a structure that can be achieved simply and at low cost, and also reducing external surges and the like. Even after the response,
An object of the present invention is to provide a circuit board that can be used continuously as it is.

[0007]

DISCLOSURE OF THE INVENTION The present invention employs the following technical means to solve the above-mentioned problems.

In other words, the circuit board provided by the present invention is a circuit board on which electronic components are mounted by conducting to conductive wires patterned on an insulating substrate and further provided with a discharge gap type surge absorber. The surge absorber penetrates in the thickness direction of the insulating substrate, and is provided in a divided region of the conductor wiring set between the input terminal or output terminal of the conductor wiring and the electronic component. And a first conductor piece electrically connected to the conductor wiring in the divided area, and a second conductor piece electrically connected to a ground terminal in the conductor wiring, and the first conductor piece is provided. And the second conductor piece are opposed to each other via the through hole.

In the surge absorber having the above configuration, when a voltage equal to or more than a predetermined value is applied to the first conductor piece by a surge voltage or the like, the second conductor opposing the first conductor piece faces the second conductor piece.
Discharge occurs toward the conductor piece. Since the second conductor piece is electrically connected to the ground terminal, excess current is discharged through the ground terminal. In this manner, in the present invention, malfunction and breakage of electronic components due to surge voltage and the like are properly avoided by the surge absorber. Moreover,
The surge absorber of the above configuration is different from the fuse,
Since the first conductor piece does not blow when an excessive voltage is applied, it is not necessary to replace the first conductor piece every time a surge voltage or the like is applied or to replace the circuit board itself. .

As described above, in the surge absorber of the present invention, the conductor wiring connecting the input or output terminal portion and the electronic component is cut in the middle, a through hole is provided in the cut portion, and the cut area is provided. Are connected by the first conductor piece,
This is achieved by connecting the second conductor piece to the ground terminal. Here, the through-holes can be formed at the same time as forming the through-holes for electrically connecting the conductor wirings provided on each of the front and back surfaces of the insulating substrate, and each conductor piece can be an electronic component or the like. In the same manner as described above, the mounting can be automatically and easily performed using a mounter or the like. As described above, the surge absorber of the present invention can be formed easily by using an existing technology and apparatus required for processing an insulating substrate and mounting electronic components. It is advantageous in terms of cost as compared with the case in which it is performed.

By the way, how much surge voltage is applied and whether an excessive current caused by the surge voltage is discharged or not, that is, the size of the discharge gap of the surge absorber is a matter of design. The number is set individually and specifically according to the number and type of electronic components mounted thereon. In order to cope with such a specific case, in a preferred embodiment of the present invention, the discharge gap is formed by an inner surface of the through hole, an internal volume of a space defined by the first conductor piece and the second conductor piece. Is adjusted by

The adjustment of the discharge gap, that is, the adjustment of the internal volume of the space, is performed, for example, by forming a concave portion or a convex portion in at least one of the first and second conductor pieces. Depending on the magnitude of the distance of the corresponding portion through the through hole, the magnitude of the internal volume of the through hole itself, the number of through holes interposed between the first conductor piece and the second conductor piece, or these means. It is adjusted by combining.

[0013] In a preferred embodiment, the first conductor piece and the second conductor piece are respectively connected to conductor wiring via solder.

The first conductor piece is provided in the middle of the conductor wiring, and the second conductor piece needs to be electrically connected to the ground terminal of the conductor wiring. Therefore, each conductor piece is connected to the conductor wiring via a conductor. There is a need to. On the other hand, electronic components are mounted on the circuit board, and the electronic components are usually connected to the circuit board via solder. For this reason, if the respective conductor pieces are connected via the solder, the respective conductor pieces can be connected together with the electronic components and the like by, for example, a solder reflow technique. Therefore, by adopting a configuration in which each conductor piece is connected by solder, the configuration of the surge absorber and its manufacturing process are simplified,
It is further advantageous in terms of cost.

After mounting the electronic parts,
Insulating resin may be applied on the circuit board in order to protect the conductor wiring and electronic components from external factors such as dust and moisture. Even in such a case, if the first and second conductor pieces are appropriately connected by solder, the coating resin does not enter the through-hole, and the initially set discharge gap is appropriately maintained. Can be.

Other advantages and features of the present invention will become more apparent from the following description of embodiments of the present invention.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings.

FIGS. 1 to 4 show an example of a circuit board according to the present invention. As shown in FIGS. 1 and 2,
The circuit board 1 has an insulating substrate 2 and a conductor wiring 3, and a surge absorber 4 is further provided in the present invention.

The insulating substrate 2 is made of, for example, glass epoxy resin or ceramic, and has a rectangular shape in plan view. In the insulating substrate 2, a through hole 20 is provided at a portion corresponding to the surge absorber 5, penetrating in the thickness direction of the insulating substrate 2.

The conductor wiring 3 is provided on each of the front and back surfaces of the insulating substrate 2 and is not clearly shown in the drawing, but the wiring on the front surface and the wiring on the back surface may have through holes as necessary. It is electrically connected through the switch. The conductor wiring 3
It has an input terminal section 30 for supplying electric power and a control signal to the electronic component 5, an output terminal section 31 for outputting a signal from the electronic component 5, and a ground terminal section 32. I have. These terminal portions 30 to 32 are formed side by side with the edge 21 of the insulating substrate 2.
Together with the edge 21 of the clip 6.
The clip 6 is used for establishing electrical continuity with another circuit board or a power supply when the circuit board 1 is assembled into a predetermined device.
0 to 32 are fixed.

Such a conductor wiring 3 is formed, for example, by forming a conductor layer on the entire insulating substrate 2 and then removing unnecessary portions by etching or using a mask corresponding to the pattern of the conductor wiring 3 to be formed. After being formed by photolithography or the like, a conductive layer is formed by electroless plating, sputtering, vapor deposition, or the like.

Of course, the configuration of the conductor wiring 3 is appropriately determined according to the use of the circuit board 1, that is, the type and number of the electronic components 5 to be mounted, and may be provided only on one surface of the insulating substrate 2. is there.

Usually, a so-called green resist (not shown) is formed on the conductor wiring 3 by using an insulating resin except for a certain area such as a pad (not shown) used when mounting the electronic component 5. Is formed. Then, the electronic component 5 is mounted on the pad after, for example, applying cream solder or the like, and the solder is re-melted and solidified, whereby the electronic component 5 is mounted.

The surge absorber 4 is for preventing the electronic component 5 from malfunctioning or being damaged by static electricity in addition to an external surge such as a lightning surge, a surge voltage generated by opening and closing of a switch. Therefore, the surge absorber 4 is provided in the middle of the conductor wiring 3, for example, between the input terminal 30 and the electronic component 5 or between the output terminal 31 and the electronic component 5. As shown in FIGS. 3 and 4, the surge absorber 4 employs a discharge gap type including the through hole 20 of the insulating substrate 2, the first conductor piece 41, and the second conductor piece 42. .

The through hole 20 is formed in a region where the conductor wiring 3 is divided. In order to make the surge absorber 4 function more effectively, as shown in FIG. It is provided near the unit 30 or the output terminal unit 31. Such a through hole 20 can be formed at the same time as, for example, forming a through hole in the insulating substrate 2.

The first conductor piece 41 closes the first opening 20a of the through hole 20 as best seen in FIG.
Further, it is provided so as to electrically connect the divided portions of the conductor wiring 3. On the other hand, the second conductor piece 42 closes the second opening 20b of the through hole 20 as well shown in FIG. 3, and the ground terminal portion of the conductor wiring 3 as well shown in FIG. Are provided so as to be electrically connected to each other. As a result, the first conductor piece 41 and the second conductor piece 42
As shown in FIG. 3, they face each other through the through hole 20.

Such first and second conductor pieces 41, 4
2 is made of, for example, a nickel plate, and is connected to the conductor wiring 3 via the solder H. The solder connection of the first and second conductor pieces 41 and 42 is performed, for example, by applying cream solder h or the like to a connection area between the first and second conductor pieces 41 and 42 in the conductor wiring 3 as well shown in FIG. After that, the first and second conductor pieces 41 and 42 are placed, and the cream solder h is melted and solidified again. Such a remelting operation of the cream solder h is performed at the same time, for example, when the electronic component 5 is mounted.

FIG. 5 schematically shows the circuit configuration of the circuit board 1 having the above configuration. That is,
Power or a control signal is input from the AC power source 6 or the like to the circuit unit 50 including the various electronic components 5 and the conductor wiring 3 via the input terminal unit 30, and the control signal is output from the circuit unit 50. The signal is output to the outside of the circuit board 1 via the output terminal 31 and the ground terminal 32.

When an external surge such as a lightning surge is applied to the circuit board 1 and a surge or static electricity is generated by opening / closing a switch, a current caused by these surges is applied to the conductor wiring 3 and the first wiring. Although the current flows through the conductor piece 41, if the current becomes excessive, the first conductor piece 4
Discharge occurs from 1 toward the second conductor piece 42. Since the second conductor piece 42 is electrically connected to the ground terminal portion 32,
Excess current is released via the ground terminal 32.

As described above, the surge absorber 4 can prevent malfunctions and damage of the electronic component 5 by avoiding the influence of an external surge or static electricity. Moreover, unlike the fuse, the surge absorber 4 does not open the circuit by fusing the first conductor piece 41 or the like to avoid the influence of an external surge, static electricity, or the like, so that a surge voltage or the like is applied. It is not necessary to replace the first conductor piece 41 or the circuit board 1 itself each time.

The surge absorber 4 having the above-described functions and effects is formed by providing the through hole 20 in the insulating substrate 2 and mounting the first and second conductor pieces 41 and 42. As described above, the through-hole 20 can be formed at the same time when the insulating substrate 2 is processed, and the first and second conductor pieces 41 and 42 can be mounted together with the electronic component 5.
The surge absorber can be configured at low cost, and is advantageous in cost as compared with the case where the surge absorber 4 is configured by a varistor.

After the electronic component 5 is mounted and the clip 6 is mounted, an insulating resin is placed on the circuit board 1 to protect the conductor wiring 3 and the electronic component 5 from external factors such as dust and moisture. It may be applied beforehand. Even in such a configuration, the first and second conductor pieces 41 and 42 are formed by solder H
Therefore, the initially set discharge gap is appropriately maintained without the application resin entering the through hole 20.

The surge absorber 4 of the present embodiment employs a discharge gap method, and the discharge gap, that is, the amount of surge voltage or excessive current generated from the first conductor piece 41 to the second conductor piece Whether or not to discharge toward 42 depends on whether the through hole 20, the first and second conductor pieces 4
It is adjusted by the internal volume of the space defined by 1,42. Specifically, it is adjusted by the shape and number of the through holes 20 and the distance between the first and second conductor pieces 41 and 42.

In order to secure a small discharge gap,
For example, as shown in FIG. 6, at least one of the first conductor piece 41 ′ and the second conductor piece 42 ′ is provided with a recess corresponding to the shape of the through hole 20, and the recess is fitted into the through hole 20. Thus, the first conductor piece 41 'or the second conductor piece 4
1 'may be implemented. Then, each conductor piece 41 ',
The distance between the conductor pieces 41 ′ and 42 ′ in the through hole 20 is smaller than that in the case where 42 ′ is a flat plate. FIG. 6 shows a distance T ₁ when the conductor pieces 41 ′ and 42 ′ are flat, and a distance between the conductor pieces 41 ′ and 42 ′ when only the first conductor piece 41 ′ is provided with a recess. To T ₂ , a conductor piece 4 in the case where a recess is provided in both conductor pieces 41 ′ and 42 ′.
1 ', 42' were respectively the distance between the T _3.

On the other hand, in order to secure a large discharge gap, at least one of the first conductor piece 41 ″ and the second conductor piece 42 ″ is formed in accordance with the shape of the through hole 20 as shown in FIG. The first conductor piece 41 ″ or the second conductor piece 41 ″ may be mounted so as to swell and make the swell portion correspond to the through hole 20. Then, each conductor piece 41 ", 42"
The distance between the conductor pieces 41 ″ and 42 ″ in the through hole 20 is larger than that in the case where is a flat plate. FIG. 7 shows the distance T ₁ when the conductor pieces 41 ″ and 42 ″ are flat, and the conductor pieces 41 ″ and 42 ′ when the bulging portions are provided on both the conductor pieces 41 ″ and 42 ″. "The distance between them is T ₄ , and the conductor piece 41" when the bulging portion is provided only in the second conductor piece 42 ",
42 "a distance between shown each T _5.

[Brief description of the drawings]

FIG. 1 is an overall perspective view on a plane side showing an example of a circuit board according to the present invention.

FIG. 2 is an overall perspective view on the bottom side showing an example of a circuit board according to the present invention.

FIG. 3 is a sectional view taken along the line III-III in FIG. 1;

FIG. 4 is an enlarged perspective view of a main part of the circuit board shown in FIGS.

FIG. 5 is a circuit diagram schematically showing a circuit configuration of the circuit board shown in FIGS. 1 to 3;

FIG. 6 is a cross-sectional view corresponding to FIG. 3, showing another example of the circuit board according to the present invention.

FIG. 7 is a cross-sectional view corresponding to FIG. 3, showing still another example of the circuit board according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circuit board 2 Insulating board 20 Through-hole (constituting surge absorber) 3 Conductor wiring 30 Input terminal part (of conductor wiring) 31 Output terminal part (of conductor wiring) 32 Ground terminal part (of conductor wiring) 4 Surge absorber 41 First conductor piece (of surge absorber) 42 Second conductor piece (of surge absorber) H Solder

Claims (6)

[Claims] 1. A circuit board which is electrically connected to conductor wiring patterned on an insulating substrate, on which an electronic component is mounted, and further comprising a discharge gap type surge absorber, wherein the surge absorber comprises the insulating substrate. And a through hole provided in a divided area of the conductor wiring set between the input terminal or output terminal of the conductor wiring and the electronic component, and in the divided area, A first conductor piece for conductively connecting the conductor wiring; and a second conductor piece for conduction to a ground terminal portion of the conductor wiring, wherein the first conductor piece and the second conductor piece penetrate through each other. A circuit board, which is arranged to face through a hole. 2. The discharge gap of the surge absorber includes an inner surface of the through hole, the first conductor piece and the second conductor piece.
The circuit board according to claim 1, wherein the circuit board is adjusted by an internal volume of a space defined by the conductor pieces. 3. The discharge gap is formed by providing a concave portion or a convex portion in at least one of the first conductor piece and the second conductor piece, so that the first conductor piece and the second conductor piece are interposed through the through hole. 3. The circuit board according to claim 2, wherein the circuit board is adjusted by setting a distance of a portion where the two conductor pieces face each other. 4. The circuit board according to claim 2, wherein the discharge gap is adjusted by an internal volume of the through hole. 5. The circuit board according to claim 2, wherein the discharge gap is adjusted by the number of the through holes interposed between the first conductor piece and the second conductor piece. . 6. The circuit board according to claim 1, wherein said first conductor piece and said second conductor piece are respectively connected to said conductor wiring via solder.