JPH10261850A - Printed circuit board and formation of printed circuit board with fuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a printed circuit board structure, wherein the circuit of a printed circuit board can be protected at low cost and reliably, by a method wherein a plurality of branched wiring patterns for fuse are provided in a wiring pattern. SOLUTION: In a printed circuit board 1, a current from a power-supply unit passes through a wiring pattern 3 on a printed wiring board 2 and is branched and split by a plurality of branched microscopic pattern parts 7, at a position where the current passes through a through hole 5. In the case where a current of a specified value or higher inclines to flow through a component to be fed with a current by some cause when a power supply of the unit is turned on and a circuit of the board 1 is actuated, an excess current other than the current of an allowable value is made to flow also through the parts 7. As a result, the parts 7 are burned to disconnect (in this case, it is normal that the parts 7 are all disconnected), the excess current is prevented from flowing through the component, and this component is protected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a printed circuit board mounted on an electronic device and a printed circuit board with a fuse.

[0002]

2. Description of the Related Art In a printed circuit board mounted on an electronic device, when a power supply is turned on and a circuit is operating, a current exceeding a specified value flows to a current-supplied component such as an IC or a motor for some reason. In this case, a fuse is provided as means for protecting the circuit by interrupting the excessive current.

FIGS. 7 and 8 show an example of a fuse used in a conventional printed circuit board. FIG. 7 shows a glass tube type fuse 51, and FIG. 8 shows a resistance type fuse 52. Is shown.

FIG. 9 shows an example of a printed circuit board using a conventional resistance type fuse 52. As shown in FIG. In FIG. 9, a printed circuit board 53 has a wiring pattern 55 on the surface of a printed wiring board 54, and a connector 56 and a current supply component 57 such as an IC or a motor are provided on the wiring pattern 55.
Has been implemented. In the middle of the wiring pattern 55, through holes 59, 59 are provided as fuse mounting seats, and the fuse 52 is soldered between the through holes 59, 59. The printed circuit board 53
Are connected to a power supply unit 58 via a connector 56 and a connection cable 60. In the printed circuit board 53, the current from the power supply unit 58
2, the current is supplied to the current-supplied component 57.

[0005]

However, in the structure of the above-mentioned conventional printed circuit board, the following (1) to (1) are required.
There is a problem as described in (3). (1) Since the fuse is separately prepared and mounted, the parts cost of the fuse itself is increased, and the cost is increased. (2) When the fuse is disconnected, there is no means for visually confirming the disconnection at a glance, and it is difficult to confirm the disconnection. Although there is a fuse having a structure capable of indicating that the fuse has blown, it is a special part, and a fuse of a type to be attached to a housing is generally used. (3) In a conventional printed circuit board, there is a method in which a fuse is also used as a printed pattern. However, the fuse is not cut off unless heat is sufficient, so that it cannot be used unless the circuit uses a large current. Further, when burned, the burnt residue may adversely affect other circuits, and thus cannot be used as a stable fuse. Furthermore, it was difficult to select a fuse having an appropriate capacity.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a structure of a printed circuit board which is inexpensive and can surely protect a circuit. Another object of the present invention is to provide a method for forming a printed circuit board with a fuse, which can easily produce a printed circuit board having a fuse having an optimum fuse capacity. Further, other objects will be clarified sequentially in the contents described below.

[0007]

In order to achieve the above object, the present invention is characterized in that the printed circuit board has the following technical means. That is, in a printed circuit board having electronic components mounted on a wiring pattern,
In this configuration, a plurality of branched wiring patterns for fuses are provided in the wiring pattern. According to this, the wiring pattern portion that is divided into a plurality of pieces and divided into pieces acts as a fuse, and when an excessive current exceeding an allowable value flows, the divided wiring pattern portion generates heat and is disconnected. Then, an excessive current is prevented from flowing through the current-supplied components.

[0008] As a method of forming a printed circuit board, a fuse portion that breaks when a current of a specified capacity or more flows in a wiring pattern on which electronic components are mounted is provided.
In the wiring pattern, a fine pattern portion which is branched into a plurality of pieces in the middle and is gathered again is provided, and the branched portions in the fine pattern portion are evaluated while disconnecting them in order, and evaluated for a fuse. In this case, a desired wiring pattern is selected. According to this method, it is possible to select a pattern fuse having an appropriate capacity while actually cutting and evaluating a fuse portion branched in a prototype stage or the like, so that selection of a pattern is simplified.

[0009]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Although the embodiments described below are preferred specific examples of the present invention, various technically preferable limitations are added thereto. However, the scope of the present invention is not limited to the particulars described in the following description. It is not limited to these forms unless otherwise stated.

FIG. 1 is a perspective view showing a configuration of a main part of a printed circuit board to which the present invention is applied, and FIG. 2 is a connection diagram of a main part of a circuit formed on the printed circuit board. In FIG. 1, a printed circuit board 1 has a printed wiring board 2 on which a wiring pattern 3 made of copper foil or the like is provided. One end of the printed wiring board 2 is connected to a power supply unit Vcc (see FIG. 2), and the other end is connected to a current supply component 4 such as an IC or a motor (see FIG. 2).
See). In the middle of the wiring pattern 3, through holes 5 and 6 are provided as parts seats, and between the through holes 5 and 6, a wiring pattern portion 7 for a fuse (hereinafter, referred to as a “fine pattern portion”). 7 ") is formed. The fine pattern portion 7 is branched into a plurality of lines (seven lines a to g in this example) by providing a plurality of stripe-shaped slits 8 in the same direction. In addition, a notification unit is connected to the wiring pattern 3 in parallel with the fine pattern portion 7. This notification means includes a photoelectric element 9 such as a light emitting diode (LED) or a photocoupler, and a resistor 10.

In the printed circuit board 1, the current from the power supply unit Vcc passes through the wiring pattern 3 on the printed wiring board 2 and passes through the through hole 5 to form a thin pattern portion branched into seven lines. 7 branches and is diverted. In addition, the currents that have passed through the seven thin pattern portions 7 are again collected in the same pattern width as before one branch, and are supplied to the current supply component 4 through the through holes 6.

When the power of the power supply unit Vcc is turned on and the circuit of the printed circuit board 1 is operating, if a current exceeding a specified value tries to flow to the current-supplied component 4 for some reason, the fine pattern portion 7 An excessive current outside the allowable value also flows. Therefore, the fine pattern portion 7 is burned and disconnected (in this case, it is common that all of the fine pattern portion 7 is disconnected). The supply component 4 is protected. Further, when the fine pattern portion 7 is disconnected,
Then, a current flows through the resistor 10 and the photoelectric element 9 is turned on to notify. As a result, an operator or the like can know that the disconnection has occurred due to an excessive current flowing. In addition, about the pattern width and the number of patterns of the fine pattern portion 7,
Specified current capacity and wiring pattern 3 on current supplied component 4 side
Is determined in consideration of the flammability of the material. Also, in setting the pattern width and the number of patterns, in the evaluation stage of the prototype, a larger pattern or a larger number of patterns than previously calculated numbers are set, and the surplus patterns are set in order. Then, if the selection is made while evaluating each time, it is possible to easily obtain the fine pattern portion 7 as a fuse having an appropriate capacity. On the other hand, after the fine pattern portion 7 is broken, the cause is solved and the cause is solved, and a spare fuse 11 is prepared. When the spare fuse 11 is soldered using the through holes 5 and 6, the circuit is restored. Is made.

Therefore, in this embodiment, the fine pattern portion 7 branched into a plurality of lines acts as a fuse, and when an excessive current exceeding the allowable value of the wiring pattern 3 flows, the fine pattern portion 7 generates heat. Since the disconnection and the protection of the excessive current from flowing to the current-supplied component 4 can be prevented, it is not necessary to prepare and install a fuse alone at least at the time of manufacturing. The cost can be reduced as compared with the structure of (1). Further, as a method of forming a printed circuit board, a branch portion in the branched fine pattern portion 7 is actually cut and selected while evaluating each time, so that a pattern fuse having an accurate capacity can be easily formed. It becomes possible to choose.

FIG. 3 is a diagram schematically showing another embodiment of the printed circuit board according to the present invention. The configuration shown in FIG.
FIG. 3 shows a multilayer printed circuit board having a wiring pattern for mounting electronic components on its surface and inside, that is, a three-layer printed circuit board. In FIG. 3, the same reference numerals as those in FIGS. 1 and 2 are used. Indicates the same as those in FIG. 1 and FIG. That is, the printed wiring board 12 shown in FIG. 3 has the wiring patterns provided on the surface layer 12A, the middle layer 12B, and the middle layer 12C, respectively, and the respective layers 12A, 12B, 12C.
In C, fine pattern portions 7A, 7B, 7C for fuses connected to each other by through holes 5, 6 are provided. Of these, the fine pattern portion 7B of the middle layer 12B and the fine pattern portion 7C of the middle layer 12C use the fine pattern having the same shape, but the fine pattern portion 7A of the surface layer 12A.
Are different from the fine pattern portions 7B and 7C. Further, in the middle layers 12B and 12C, when the fine pattern portion 7B or 7C is burned, the burnt residue adheres to other wiring patterns provided therearound and adversely affects the circuit. In order to eliminate the problem, a region 13 where no wiring pattern is formed is provided around the fine pattern portions 7B and 7C. FIG.
It is a figure which expands and shows the peripheral structure of fine pattern parts 7B and 7C in B and 12C. Therefore, in the structure of the printed circuit board shown in FIG. 3, the fine pattern portions 7A, 7B, and 7C serving as fuses are formed by the respective layers 12A, 12A, 12B.
B and 12C are provided separately.
In addition to the effects described with respect to the printed circuit board shown in (1), the wiring area of the fine pattern portion is reduced by the area of the entire circuit board (each layer 12A,
12B, 12C).

FIG. 5 is a view schematically showing still another embodiment of the printed circuit board according to the present invention. In FIG. 5, the same reference numerals as in FIGS. 1 to 4 denote the same components as in FIGS. 1 to 4. The printed wiring board 21 of the embodiment shown in FIG. 5 is of a two-layer board type composed of a surface layer 22A and an intermediate layer 22B.
2A and the middle layer 22B are provided at different positions, and one fine pattern portion 7 is used as a spare fuse, which can be switched and used by a short-circuit plug (not shown) or the like. That is, first, the surface layer 22
When the fine pattern portion 7 on the surface layer A is broken and used, the middle layer 22B
The thin pattern portion 7 on the side can be switched and used with a short-circuit plug so as to be effective. Therefore, in the structure of the printed circuit board, the circuit can be restored once by using the spare fuse incorporated in the printed circuit board without separately preparing a spare fuse.

FIG. 6 is a view schematically showing still another embodiment of the printed circuit board according to the present invention. In FIG. 6, the same reference numerals as those in FIGS.
It shows the same thing as. The printed wiring board 31 of the form shown in FIG. 6 has a surface layer 32A, an intermediate layer 32B,
A four-layer substrate type consisting of 2C and 32D;
And fine pattern part 7 for fuses normally used for 32C
(A) and a fine pattern portion 7 (B) for a spare fuse are provided. Also in this embodiment, by switching from the fine pattern portion 7 (A) to the fine pattern portion 7 (B) using the short-circuit plug, the circuit can be restored once without preparing a spare fuse.

[0017]

As described above, according to the present invention,
The wiring pattern portion that is divided into a plurality of pieces and functions as a fuse acts as a fuse. When an excessive current that exceeds the allowable value of the pattern flows, the wiring pattern portion that has been divided and cuts due to heat generation. The current supply components can be protected from excessive current flow, so there is no need to separately prepare and incorporate a fuse, reducing costs compared to conventional printed circuit board structures. Will be possible. Also, as a method of forming a printed circuit,
Since the branched fuse portion in the wiring pattern can be actually cut and evaluated, it is possible to expect an effect such that a pattern fuse having an appropriate capacity can be easily selected.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a main part of a printed circuit board according to the present invention.

FIG. 2 is a connection diagram of a main part of a circuit formed on a printed circuit board.

FIG. 3 is a perspective view schematically showing another embodiment of the printed circuit board according to the present invention.

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

FIG. 5 is a perspective view schematically showing still another embodiment of the printed circuit board according to the present invention.

FIG. 6 is a perspective view schematically showing still another embodiment of the printed circuit board according to the present invention.

FIG. 7 is a perspective view showing an example of a fuse.

FIG. 8 is a perspective view showing another example of the fuse.

FIG. 9 is a perspective view schematically showing an example of a conventional printed circuit board.

[Explanation of symbols]

 1, 12, 21, 31 Printed circuit board 2 Printed wiring board 3 Wiring pattern 4 Current supply component 5, 6 Through hole 7, 7A, 7B, 7C Fine pattern portion 9 Photoelectric element (notifying means) 11 Spare fuse

Claims (6)

[Claims] 1. A printed circuit board having electronic components mounted on a wiring pattern, wherein a plurality of branched wiring pattern portions for fuses are provided in the wiring pattern. . 2. The printed circuit board according to claim 1, further comprising means for detecting and reporting when the wiring pattern portion for the fuse is disconnected in the wiring pattern. 3. A printed circuit board provided with a multilayer printed wiring board provided with wiring patterns for mounting electronic components on the surface and inside thereof, wherein a plurality of fuse wiring pattern portions are provided. A printed circuit board characterized in that said wiring pattern portion is provided separately for each layer. 4. The printed circuit board according to claim 3, wherein a region where no wiring pattern is provided around the wiring pattern portion so as not to be affected by the damaged wiring pattern portion. 5. A printed circuit board provided with a printed wiring board formed in a multi-layered form by providing wiring patterns for mounting electronic components on the surface and inside thereof, wherein a plurality of wiring patterns are provided in two or more of the wiring patterns. A printed circuit board, wherein a plurality of branched wiring pattern portions for a fuse are provided, and at least one of the wiring pattern portions is used as a spare fuse. 6. A fuse portion which is disconnected when a current of a specified capacity or more flows in a wiring pattern on which an electronic component is mounted, is branched into a plurality of pieces in the wiring pattern and assembled together again. A thin pattern portion is provided, and the branched portions in the fine pattern portion are sequentially evaluated while being disconnected, and a desired wiring pattern for a fuse is selected. Method of forming a printed circuit board with an attachment.