JP2011243918A - Circuit board and electrical equipment equipped with circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board capable of suppressing fire-spread of a board caused by carbonization burning from cracking or the like.SOLUTION: Branch wirings 18a and 18b, a cut pattern, and a void pattern are formed, at a proper part of a land 11 portion corresponding to an electric component through which a large current flows. The branch wirings 18a and 18b branch from a main wiring 10 containing the land 11 portion, with at least one branch wiring being arranged to correspond to one land 11 portion. The branch wirings 18a and 18b branch from the main wiring 10, with branch points A and B being away from the land 11 portion by a predetermined distance, to be parallel to the main wiring 10, with the main wiring 10 in between. The widths of them are identical with the main wiring 10, with the direction of extension from the branch point being reversal. The length of extension of the branch wiring 18 is desired to be extended as far as the center position of the land 11 portion.

Description

  The present invention relates to an electric circuit board for printed wiring and an electric (electronic) device including the circuit board.

  Various electrical products exist as electrical equipment that uses a commercial power source. For example, electric appliances are used by general companies including household appliances such as microwave ovens, electric refrigerators, televisions, fans, air conditioners (air conditioners including air purifiers), electric appliances, and combustion appliances. There are various devices such as personal computers (PCs), copying machines, fax machines, and printers.

  As the commercial power source, a single-phase AC power source such as an execution voltage of 100 V or 200 V, a three-phase AC power source or the like such as a press machine using an induction motor or the like is generally used.

  For electrical equipment that uses such an AC power supply, a voltage is supplied to a load such as a motor, a nichrome wire, a magnetron, a control circuit board, and the like. It is used as an alternating current that has been stepped down and converted into a voltage, and the alternating current is once rectified, that is, converted into a direct current. For this reason, the power plug is connected to an outlet, and the end on the opposite side through the plug cord, that is, the electrical equipment side, is connected to the electric circuit board for the power source for using the AC power source in direct current or alternating current. The

  The circuit board for the power supply is provided with wiring patterns for electrically connecting various electric (electronic) components, and lands for soldering the patterns, and terminals of the electric components are soldered to the lands. Attached. In such a circuit board for power supply, a current having a large ampere (A) order generally flows. Therefore, when a soldering failure occurs, the electrical contact of the part is not stable, arc discharge or the like occurs, and the heat generated by the discharge carbonizes, burns, and ignites the board of the soldered part. It is conceivable to spread the fire to the entire substrate.

  Usually, before shipping electrical equipment, from the viewpoint of quality control on the manufacturer side and other PL methods, sufficient measures are taken for defects such as soldering, and circuit boards without such defects are taken. It is actually installed in the product.

  However, when an electric device is used for many years, a terminal of an electric component and a solder crack (peeling) may occur in a soldered portion due to secular change, vibration, or the like. For this reason, such a risk is predicted, a time stamp or the like is used for a certain device, and a certain maintenance is performed for an electric device exceeding 10 years, for example, about 10 years. Proposals have been made to make the system unusable without replacement.

  Further, a power supply circuit board that prevents heat generation, ignition, etc. due to leakage or the like has been proposed in, for example, Japanese Patent Application Laid-Open No. 5-53259 (Japanese Utility Model Application No. 3-103001). Yes. This is because, for example, in order to prevent the condensed water condensed on the cathode ray tube from dripping onto the AC connector portion of the power circuit board and causing the circuit board to generate heat and ignite due to leakage, etc., a slit is provided between the opposite poles of the AC power supply. To form. By configuring in this way, when condensed water falls (drops), it falls to the lower part of the circuit board through the slit, so that it is possible to prevent leakage between the different polarities of the AC power source, I try to prevent ignition.

  However, even in Patent Document 1, it can be predicted that, for example, a crack or the like occurs in the soldered portion of the connector portion of the AC power source due to secular change, vibration, or the like, resulting in poor contact. However, heat generation, ignition, etc. due to arc discharge caused by such poor contact cannot be prevented simply by providing a slit between the different polarities, and as a result, the substrate cannot be solved even if it spreads.

  On the other hand, Patent Document 2 (Japanese Patent Laid-Open No. 3-1480) discloses a technique for preventing heat generation, ignition, and fire spreading of a circuit board due to a crack in a soldered portion. It is disclosed that a check pattern for detecting heat generation that is different from the wiring pattern of the power supply circuit is provided along the periphery of the wiring pattern of the land portion on the power supply circuit board. Both ends of this check pattern (wiring) are used as detection terminals. For this reason, an arc discharge due to a crack or the like occurs, and the portion generates heat and ignites, so that the ignition state is detected by utilizing the fact that the tic pattern is cut off. Based on this detection, the power supply is cut off.

Japanese Utility Model Publication No. 5-53259 (Japanese Utility Model Application No. 3-103001) JP-A-3-1480

  According to the invention described in Patent Document 1 described above, it is possible to prevent heat generation and ignition due to dew condensation on the power circuit board. However, it is difficult to prevent heat generation, ignition, and fire spreading of the circuit board due to arc discharge caused by a crack in a soldered portion (land portion) in the wiring pattern of the power circuit board. Further, there is a problem that the strength of the substrate is impaired by providing the slits in the power circuit board.

  In this regard, according to Patent Document 2, it is possible to detect the heat generation and ignition due to the crack in the soldered portion, and to cut off the power supply before spreading the fire. As a result, it is disclosed that arc discharge is stopped and fire spread is suppressed. However, in many cases, the wiring pattern to be ignited is a temporary wiring pattern, and a considerable insulation distance is required for the check pattern. Therefore, if the substrate ignites, the fire spread continues until the check wiring pattern that is separated from the ignited wiring pattern by a necessary insulation distance is disconnected, and the substrate combustion is expanded at the time when the ignition is detected.

  Therefore, for any of the inventions described in Patent Documents 1 and 2, when the substrate ignites, the fire spread cannot be eliminated, and there is a fire spread on a substrate on which a considerable number of electrical components are arranged. There is a problem that the fire spreads to other parts.

  In addition, as described above, the description has been given of ignition and fire spread in the case where a crack of a soldering part occurs due to secular change, vibration, etc. of an electric device, but not limited to these, in general those caused by poor soldering, The problem as described above will occur.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a circuit board that can suppress the loss of the board when ignited by heat generated by arc discharge or the like. Yes.

  Moreover, the objective of this invention is preventing the fire spread to an electric equipment main body by suppressing the loss by the fire spread of a power supply circuit board, for example in an electric equipment provided with a power supply circuit board. In other words, the present invention aims to prevent the spread of fire to an electric device including the power circuit board by achieving the above-described object.

  The circuit board of the present invention described below will be described by taking a power supply circuit as an example. However, this is not the case, and it is needless to say that the circuit board can be applied to all circuit boards through which a large current flows.

  In order to solve the above-described problem, in a circuit board formed with a conductive wiring pattern for electrically connecting terminals of an electrical component, a land for electrically connecting the terminal of the electrical component; Provided is a circuit board comprising a main wiring having a land and a branch wiring branched from the main wiring corresponding to the land.

  Thus, by providing the branch wiring that branches from the main wiring having the land, it is possible to operate the circuit board fire spreading from the land due to soldering cracks in the direction in which there is less combustible material and to prevent the spread of the fire spreading. .

  Further, by arranging the branch wiring on both sides of the land, it is possible to reliably prevent the spread of the fire spreading from the land in a concentric manner.

  In addition, by arranging a gap that penetrates the circuit board between the main wiring and the branch wiring, when the spread of fire reaches the gap, combustion is stopped and the combustion state is subdued, that is, the fire is extinguished and extinguished. By disposing the gap at the end of the branch wiring, it is possible to more reliably prevent the spread of fire.

  Moreover, by making the width of the branch wiring smaller than the width of the main wiring, the portion where the wiring is arranged can be reduced, and the substrate can be miniaturized.

  A circuit board formed with a conductive wiring pattern for electrically connecting the terminals of the electrical component; a land for electrically connecting the terminals of the electrical component; and a main wiring having the land. A circuit board having a notch pattern for defining the main wiring into a main wiring pattern and a branch wiring pattern, and having the notch pattern provided at a position corresponding to the land is provided.

  By doing so, it is not necessary to provide a structure for preventing the spread of fire separately from the main wiring, and the design can be made without being aware of the structure of preventing the spread of fire.

  In addition, a void portion penetrating the substrate is arranged in the notch pattern.

  Further, by making the width of the branch wiring pattern larger than the width of the main wiring pattern, a larger current can be passed.

  The circuit board configured as described above is built in as a circuit board of an electric device that operates with supplied power.

  Accordingly, cracks occur in the soldered portion on the circuit board side, particularly on the circuit board side where a large current flows in the power supply portion, and it is possible to suppress the spread of the circuit board even if heat is generated and burned.

  According to the circuit board having the configuration described above, it is possible to suppress the spread of the circuit board when cracks or the like occur in the soldered portion of the circuit board.

The top view which looked at the circuit board concerning this invention from the wiring pattern side. The circuit diagram which shows the circuit structure by which various electrical components are electrically connected to the circuit board concerning this invention. The figure for demonstrating an example of the branch wiring formed corresponding to the land part to solder in the circuit board concerning this invention. The figure for demonstrating the other example of the branch wiring formed corresponding to the land part to solder in the circuit board in this invention. The figure for demonstrating the other example of the branch wiring formed corresponding to the land part to solder in the circuit board in this invention. The figure for demonstrating the order which suppresses a fire spread by the circuit board in this invention. The figure for demonstrating the other example of the branch wiring formed corresponding to the land part to solder in the circuit board in this invention. The figure for demonstrating the order which spreads fire prevention with the circuit board in this invention. The figure for demonstrating the other example of the branch wiring formed corresponding to the land part to solder in the circuit board in this invention. The figure for demonstrating the other example of the branch wiring formed corresponding to the land part to solder in the circuit board in this invention. The figure for demonstrating the notch pattern formed corresponding to the land part to solder in the circuit board in this invention. The figure for demonstrating the other example of the notch pattern formed corresponding to the land part to solder in the circuit board in this invention. The figure for demonstrating the other example of the notch pattern formed corresponding to the land part to solder in the circuit board in this invention. The figure for demonstrating the order which reaches a fire spread state in the conventional circuit board. The figure for demonstrating the condition where it spreads by the same-polarity tracking in the conventional circuit board. The figure for demonstrating the condition which spreads by the tracking between different poles in the conventional circuit board.

  Embodiments of the present invention will be described below with reference to the drawings. An example of the electric circuit board of the present invention is shown in FIGS. FIGS. 1 and 2 illustrate a power supply circuit board as an example.

  Normally, an electric (electronic) device is supplied with power (electric power), thereby realizing an operation and control desired by a user by control of a control unit (not shown). For example, in a washing machine, the plug at the end of the cord, which is a power supply line, is plugged into an AC outlet of 100V (execution voltage), and the power switch of the washing machine body is operated (ON) to select the desired washing program If operated, for example, a washing operation including dehydration is automatically started.

  The electrical equipment as described above is not limited to a washing machine, and is the same for all types of electrical products installed in the home. By including the circuit board of the present invention described below, the power supply Supply is possible. In addition, not only household electric appliances but also all electric appliances that operate by receiving power supply, such as products that use electricity in companies, such as copiers, printers, and PCs.

  In the electrical equipment as described above, a cord for receiving power supply is connected to the power supply circuit board. The circuit board is connected to electrical (electronic) components such as a transformer that boosts and lowers the AC voltage according to the type of electrical equipment. In addition, when the electrical equipment operates with DC (direct current) instead of AC, electrical components such as a rectifier for converting alternating current into direct current are necessary for AC and DC, respectively. Are connected to each other. This is a well-known technique.

  The circuit for supplying power shown in FIG. 2 is provided with various electrical components on the circuit board 1 (front surface), each terminal is inserted into the back surface of the circuit board 1, and is connected via a wiring pattern formed on the back surface. The This circuit board 1 is an example in which a DC voltage obtained by converting alternating current into direct current is used as an electrical device. Power is supplied to the power circuit board 1 from the plug inserted into the AC (100 V) power supply (outlet) 14 via the electric cord 16.

  The other end (the side opposite to the plug) of the power cord 16 is connected to a coupling connector (not shown), which can be attached to and detached from the AC input connector 2 provided on the power circuit board 1 of the electrical equipment. The power is supplied to the circuit board 1 by being coupled.

  An output connector 9 is provided on the side opposite to the input side of the circuit board 1, and a receiving connector (not shown) provided on a supply line 17 that supplies a DC voltage to a load 15 of an electrical device. Z)). Therefore, the circuit board 1 can be easily removed by removing both the input / output connectors 2 and 9 and the mating connector, and the circuit board can be easily replaced and maintained. .

  On one surface (back surface) of the circuit board 1, there is formed a wiring pattern 10 made of copper foil (copper plate) or the like for connecting various electrical components as shown in FIG. Terminals of various electrical components are inserted into the wiring pattern 10 from the opposite surface side through through holes formed corresponding to the respective wiring patterns, and soldered portions (lands) 11 corresponding to the through holes. Is formed. Electrical connection is established by soldering the terminals of the electrical components inserted in the lands 11 of the wiring pattern 10. The land 11 is shown in a circular shape in the figure, and soldering is performed on the circular portion.

  A circuit configuration in which each electrical component is electrically connected via the wiring pattern 10 of the circuit board 1 shown in FIG. 1 will be described below with reference to FIG. As shown in the figure, one end of an AC input connector 2 serving as an input portion of an AC power source is connected to one end of a current fuse 3 via a wiring pattern 10. The other end of the current fuse 3 is connected to one end side of a noise removing capacitor 4 a, and the other end of the noise removing capacitor 4 a is connected to the other end side of the AC input connector 2.

  Both ends of the noise removing capacitor 4a are connected to one terminal of the choke coil 5, and the other end of the choke coil 5 is connected to each terminal of the noise removing capacitor 4b. Both ends of the noise removing capacitor 4b are connected to the input terminal side of the diode bridge 6 constituting the full-wave rectifier, and the smoothing electrolytic capacitor 7 is connected in parallel to the output terminal side of the diode bridge 6. . In parallel with the smoothing electrolytic capacitor 7, a noise removing capacitor 4c and a discharge resistor 8 for discharging the electric charge of the smoothing electrolytic capacitor 7 are connected.

  The DC component voltage (DC) smoothed by the smoothing electrolytic capacitor 7 is supplied to a load 15 of an electric device such as a DC motor (motor) through the output connector 9 and the supply line 17.

  The discharge resistor 8 is connected to release the electric charge charged in the smoothing electrolytic capacitor 7 when the electric load 9 becomes open for some reason, that is, to release the charged electric charge.

  As described above, the wiring pattern 10 as shown in FIG. 1 is formed on the power supply circuit board 1 in order to electrically connect each of the various electrical components constituting the power supply circuit shown in FIG. ing. The wiring pattern 10 is formed based on a well-known technique, and soldering lands 11 are formed in order to electrically connect the terminals of each electrical component to the wiring pattern 10.

  In FIG. 1, as described above, the circular portion is each land 11 for soldering, and is soldered only to that region. Other portions are printed (coated) with an insulating material or the like so that solder does not adhere. Further, rectangles and ellipses indicated by broken lines in FIG. 1 indicate the various electric components described above, and the electric components are denoted by the same reference numerals, and the circuit board 1 main body is made of resinous insulation. It consists of members.

  The circuit board 1 in the present invention is burned by arc discharge or the like when a crack is generated in the land 11 part, the part generates heat, the insulating resin circuit board 1 is carbonized, and power supply continues. In order to prevent this from spreading through the circuit board 1, branch wiring 18, a notch pattern 22, and a gap portion 19, which will be described later, are formed corresponding to each land 11.

  The branch wiring 18, the cut pattern 22, and the gap portion 19 are not provided corresponding to all the lands 11, but are formed corresponding to the land portions of the terminal of the circuit component through which a particularly large current flows.

  For example, as shown in FIG. 2, a portion where a large current flows through each electrical component of the power supply circuit is indicated by an arrow 13, and this is a portion where arc discharge or the like is likely to occur due to a crack or the like. In this power supply circuit, almost no current flows through the noise removing capacitors 4a to 4c, and a current on the order of several mA or μA flows. For other electrical components, a large current (several hundred mA to A order) flows.

  Therefore, if a terminal of one electrical component constituting the electrical circuit is cracked due to some factor, such as vibration, at a soldered portion (land portion), between the solder portion and the terminal, or between the wiring pattern 10 and the electrical component. Arc discharge occurs due to contact failure or failure between terminals. It is predicted that the substrate of that portion is carbonized by the sparks caused by this discharge, and then burned and spread along the substrate 1 to spread.

  For this reason, the branch wiring 18, the notch pattern 22, and the gap 19 described above are formed at appropriate positions in the land 11 corresponding to the electrical component through which a large current flows.

(Branch wiring)
The branch wiring 18 will be described in detail with reference to FIG. The branch wirings 18a and 18b branch from the main wiring 10 having the land 11 portion and are formed so as to correspond to the land 11 portion.

  In order to cope with this, at least one branch wiring 18 is arranged for each land 11 portion so as to suppress the spread of fire from the land 11 portion.

  Further, the branch wirings 18a and 18b branch from the branch point A and B to the main wiring 10 with the points a predetermined distance away from the land 11 as branch points A and B. The branch wirings 18a and 18b are arranged in parallel with the main wiring 10 with the main wiring 10 in between, the width is the same as that of the main wiring 10, and the direction extending from the branch point is opposite. ing. It is desirable that the length of the branch wiring 18 is extended to reach the center position of the land 11 portion.

  However, since the direction in which the branch wiring 18 is extended is determined by the arrangement with other electrical components, it is not limited to the reverse direction, and may be the same direction as shown in FIG. The distance from the branch points A and B is preferably equal because the fire spread spreads concentrically. However, the lengths of the branch wirings 18a and 18b may be different depending on the arrangement of components.

  As shown in FIG. 5, when the main wiring 10 is formed near the substrate end 1a of the circuit board 1, there is no possibility of spreading in the direction of the end 1a. You may arrange | position only to the one side which is the other side of the board | substrate edge part 1a on both sides of this wiring 10. FIG.

(Principle of fire spread suppression)
As described above, the power circuit board 1 according to the present invention is configured. The operation of the circuit board 1 of the present invention, that is, the process leading to carbonization and combustion of the substrate, the principle of suppressing the combustion, and the like will be described below.

  First, referring to FIG. 14, not only the configuration of the circuit board 1 in the present invention described above but also the progress (flow / flow) until the fire spreads in the case of a conventional circuit board in which the branch wiring 18 is not formed will be described. Moreover, about the code | symbol shown in FIG. 14 etc., the same part as the circuit board 1 of this invention is shown with the same code | symbol.

  First, as shown in FIG. 14, when a crack occurs in the solder at the land 11 portion due to secular change or vibration in step S11, an arc discharge 30 is generated at the crack portion. If this continues, the process proceeds to step S12, where the arc discharge 30 causes carbonization 31 of the substrate itself, and thus combustion starts in the land 11 portion. Thereby, carbonization combustion advances, it changes to step S13, and a carbonization part becomes large gradually, carbonization combustion expands, and the big hole 32 opens in the part which the board | substrate 1 burned out. This continues, and finally the process proceeds to step S14, which is exposed to the risk of spreading to the entire substrate 1 due to this.

  Thus, if the carbonization combustion expands and spreads through the circuit board 1, the wiring in the corresponding land 11 portion is disconnected, and the power supply, that is, the combustion state is not extinguished unless the combustion state is extinguished even if the current stops flowing. It is not possible to suppress the ignition. In addition, when the carbonized portion becomes conductive and conducts with another inter-wiring pattern, the result is that oil is poured into the carbonization and combustion, and the spread of fire spreads. As a result, there are concerns about ignition of electrical equipment.

  On the other hand, the effect | action in the structure of the circuit board 1 of this invention is demonstrated along FIG.

  First, in step S1 of FIG. 6, when a crack occurs in the portion of the soldering land 11 for some reason as in the conventional case, an arc discharge 30 is generated. Thereby, it transfers to step S2, the carbonization 31 of the board | substrate 1 arises, and combustion starts in the land 11 part. The steps so far are the same as steps S11 and S12 of FIG.

  Next, when carbonized combustion spreads concentrically around the land 11 portion and proceeds to step S3, this reaches the branch wirings 18a and 18b.

  Then, when the carbonized combustion reaches the branch wirings 18a and 18b, the process proceeds to step 4 and the carbonized combustion of the circuit board 1 proceeds along the branch wirings 18a and 18b toward the open end as indicated by arrows.

  Here, the interval between the main wiring 10 and the branch wiring 18 is narrow, and the combustion power (impedance is small) at the time of tracking is small.

  Further, since the main wiring 10 and the branch wiring 18 have the same polarity, no discharge or the like is generated in the closed end direction (the direction where the branch point is present), so that the fire spread does not proceed in the closed end direction.

  Further, if the spread of fire spreads until the main wiring 10 is disconnected, the substrate 1 alone is more likely to burn than the main wiring 10, the branch wiring 18 (copper foil), and the substrate 1 are burned together. Combustion proceeds.

  As described above, according to the circuit board 1 of the present invention, by providing the branch wiring 18, for example, arc discharge due to poor soldering occurs, and even if carbonization and combustion of the board occur due to this, the spreading direction of this The fire spread of the circuit board 1 can be suppressed by spreading in a direction with less combustible material.

  Further, according to the present invention, carbonization combustion is suppressed by a very simple configuration in which the branch wiring 18 is provided at an appropriate position on the circuit board 1, particularly at a position corresponding to the land 11 of the soldered portion along the wiring pattern 10. The effect to do. Therefore, it is not necessary to separately provide a special circuit configuration for detecting ignition, and a control circuit that electrically cuts off the power supply is not required.

(Second embodiment of the present invention)
This embodiment is the same as the first embodiment in that the branch wiring is provided at a position corresponding to the land portion, but differs in that there is a gap that penetrates the circuit board between the main wiring and the branch wiring.

  In the invention according to the first embodiment, it is possible to suppress the fire spread by changing the fire spread direction, but it is difficult to completely suppress the fire spread.

  Therefore, in this embodiment, as shown in FIG. 7, gaps 19a and 19b penetrating the circuit board 1 are provided between the main wiring 10 and the branch wirings 18a and 18b. The gaps 19a and 19b are preferably disposed between the broken line L passing through the center of the land 11 and the terminal ends 18c and 18d of the branch wirings 18a and 18b.

  The effect | action of the invention which concerns on this embodiment is demonstrated using FIG. In FIG. 8, steps S1 to S4 are the same as those in FIG. In step S5, which is the final step, the fire spreads along the branch wirings 18a and 18b. When the fire spread reaches the gaps 19a and 19b disposed between the main wiring 10 and the branch wirings 18a and 18b, the fire spread is suppressed there. Further, it is possible to prevent the spread of fire from spreading further.

  Here, when the burned part falls to the lower part of the circuit board 1 in the middle, in order to receive this, a non-combustible member, for example, a metal plate or the like is provided on the bottom surface of the electric device as a tray. What should I do? As a result, it is possible to prevent the spread of fire to others caused by falling objects such as burned debris, and in turn, it is possible to prevent the ignition and the spread of fire in electrical equipment.

  As described above, according to the invention of the present embodiment, the direction of the fire spread is manipulated to prevent the fire spread from reaching other combustible parts, and the fire spread can be suppressed, so that the fire spread is suppressed in a very small range. Can do.

  Also, as shown in FIG. 9, since the gaps 19a and 19b are provided in the vicinity of the terminal ends 18c and 18d of the branch wirings 18a and 18b, the distance between the land 11 and the gaps 19a and 19b can be increased. Even if the fire spread occurring in the 11 portion spreads widely, the fire spread can be prevented more reliably.

  Further, in the present invention, the thicknesses of the branch wirings 18a and 18b are not particularly limited. However, by making the branch wirings 18a and 18b smaller than the width of the main wiring 10 as shown in FIG. The distance between them can be reduced, and the entire circuit can be reduced in size.

(Third embodiment of the present invention)
This embodiment is the same as the first embodiment in that the fire spread prevention structure is disposed at a position corresponding to the land portion, but differs in that a branch wiring is not provided and a part of this wiring has a notch pattern. .

  The invention according to this embodiment will be described with reference to FIG. In the present embodiment, the main wiring 10 having the land 11 portion and the notch patterns 22a and 22b for separating the main wiring 10 into the main wiring pattern 21 and the branch wiring patterns 20a and 20b are provided corresponding to the land 11 portion.

  Corresponding to this means that at least one notch pattern 22 is arranged for each land 11 portion so as to suppress the spread of fire from the land 11 portion.

  The operation of the invention according to the present embodiment is the same as that of the invention according to the first embodiment described in FIG. 5. After the land 11 portion starts to burn due to the arc current, the wiring pattern 21 is spread and then branched. When the fire spread reaches the wiring patterns 20a, 20b, the fire spread proceeds along the branch wiring patterns 20a, 20b, so that the direction of the fire spread can be manipulated as in the invention according to the first embodiment, Fire spread to other combustible parts can be suppressed.

  The cutting pattern separates the main wiring pattern and the branch wiring pattern from the starting points C and D as starting points C and D that are separated from the land 11 by a predetermined distance. The cutting pattern is arranged in parallel to the main wiring pattern with the main wiring pattern interposed therebetween.

  The widths of the main wiring pattern 21 and the branch wiring patterns 20a and 20b separated by the cutting patterns 22a and 22b are not particularly limited, but the width of the main wiring pattern 21 is larger than the branch wiring patterns 20a and 20b. It is preferable because a large current can flow.

  In addition, the direction in which the cutting patterns 22a and 22b are extended from the starting points C and D is opposite, but the direction in which the cutting patterns 20a and 20b are extended depends on the arrangement with other electrical components. It is not limited to the reverse direction.

  Further, it is desirable that the cut patterns 20a and 20b are extended from the start points C and D to a length that reaches the center of the land 11 portion.

  As shown in FIG. 12, by providing the gaps 19a and 19b penetrating the circuit board 1 on the notch patterns 20a and 20b, it is possible to suppress the fire spread in the gaps 19a and 19b. In addition, it is possible to prevent the circuit board 1 from spreading.

  It is desirable that the gaps 19a and 19b are arranged on the cutting patterns 20a and 20b and between the broken line L passing through the center of the land 11 and the starting points C and D of the cutting patterns 20a and 20b.

  Further, as shown in FIG. 13, when the main wiring 10 is formed near the end 1a of the circuit board 1, there is no possibility of spreading in the direction of the end 1a. You may arrange | position only to one side of this wiring 10 which is the other side of the edge part 1a.

(Fire spread due to different wiring pattern forms)
In addition, in order to further verify the effect of the circuit board 1 of the present invention that prevents carbonization combustion according to the present invention and further the spread of fire, the process of conventional carbonization, combustion, ignition, and further, due to the difference in the wiring pattern. Explain the differences. In this regard, in the present invention, carbonization, combustion, and fire spread due to this can be prevented regardless of the difference in the wiring pattern.

  FIG. 15 is a view for explaining the process of fire spreading in the state where the wiring pattern 10 on which the land 11 is formed as described in FIG. This will be described as the spread of fire in the same-polarity tracking state.

  First, step S15 in FIG. 15 is in the same state as step S14 described in FIG.

  That is, if the arc discharge is continuously caused, the process proceeds to step S14 in FIG. 14, the combustion of the circuit board 1 spreads, and the process becomes step S15 in FIG. Here, the portion carbonized 31 by the combustion 33 spreads widely around the land. If it further spreads, it gradually expands along the wiring pattern 10 as shown in step S16.

  In this case, the carbonized portion 31 becomes a conductive path, and the arc discharge 30 is repeated between the wiring pattern 10 and the portion. In this arc discharge 30, even if a part of the wiring pattern 10 burns out due to the combustion 33 of the substrate 1 and is lost, the arc discharge 30 recurs at the end of the wiring pattern 10 through the carbonized conductive path (31) of the substrate 1. This arc discharge 30 continues. As a result, homopolar tracking that spreads along the wiring pattern 10 of the circuit board 1 is caused and proceeds in the direction of the power supply that is the power supply source (in FIG. 15, the right side is the power supply source side).

  On the other hand, FIG. 16 shows a process in which carbonization and fire spread occur due to cracks in the land 11 when the wiring pattern 10A having the land 11 is adjacent to the wiring pattern 10A having a different polarity. Yes. This will be described below as heteropolar tracking.

  In FIG. 16, as described above, the process after step S14 in FIG. 14 is shown. In other words, as shown in step S150 in FIG. 16, the combustion 33 of the circuit board 1 has spread.

  The combustion 33 spreads, transitions to step S151, and reaches the wiring pattern 10A side of the adjacent different polarity. At this point, the circuit board 1A becomes short-circuited through the conductive path carbonized 31 with the wiring pattern 10A. As a result, as shown in step S152, there is a risk of proceeding to tracking between different polarities, igniting intensely, and spreading to the entire circuit board 1.

  This interpolar tracking proceeds in a shorter time than the above-described homopolar tracking shown in FIG. This is particularly the case when the wiring pattern 10A having a different polarity is formed adjacent to the wiring pattern 10 through which a large current flows.

  In this regard, the branch wiring 18 or the cut pattern 22 is formed corresponding to the circuit board 1 of the present invention, that is, the land 11 of the wiring pattern 10 through which a large current flows, so that even if heat generation or carbonization combustion occurs due to arc discharge. Further, since the operation can be performed so that the fire spread proceeds along the branch wiring 18 or the branch wiring pattern 20, it is possible to suppress the occurrence of the above-described heteropolar tracking.

  In the present invention, the large current is 1 A or more, and even when a current of about 100 V and 0.1 A flows, arc discharge occurs due to solder cracks, and as described above, carbonization, carbonization combustion, etc. occur. It was confirmed.

1 Circuit board 2 Connector for input (electrical parts)
3 Current fuse (electrical parts)
4 Noise removal capacitors (electrical parts)
5 Choke coil (electric parts)
6 Diode bridge (electric parts)
7 Electrolytic capacitors for smoothing (electric parts)
9 Output connector (electrical parts)
10 Wiring pattern (main wiring)
11 Land (soldering part)
12 Slit 13 High Current Flow Path 14 Commercial Power Supply 15 Load 16 Electric Cord 17 Supply Line 18 Branch Wiring 19 Gap 20 Branch Wiring Pattern 21 Main Wiring Pattern 22 Cutting Pattern

Claims (9)

In a circuit board formed with a conductive wiring pattern to electrically connect terminals of electrical components,
A land for electrically connecting terminals of the electrical component;
A main wiring having the land;
A circuit board having a branch wiring branching from the main wiring corresponding to the land.   The circuit board according to claim 1, wherein the branch wiring is disposed on both sides of the land.   The circuit board according to claim 1, wherein a gap portion that penetrates the circuit board is disposed between the main wiring and the branch wiring.   The circuit board according to claim 3, wherein the gap is disposed at an end of the branch wiring.   5. The circuit board according to claim 1, wherein the branch wiring has a width smaller than that of the main wiring. In a circuit board formed with a conductive wiring pattern to electrically connect terminals of electrical components,
A land for electrically connecting terminals of the electrical component;
A main wiring having the land;
A cutting pattern that defines the main wiring into a main wiring pattern and a branch wiring pattern,
A circuit board, wherein the notch pattern is provided at a position corresponding to the land.   The circuit board according to claim 6, wherein a gap portion penetrating the circuit board is disposed in the notch pattern.   The circuit board according to claim 6, wherein the main wiring has a width larger than that of the branch wiring pattern.   An electric device comprising the circuit board according to any one of claims 1 to 8 for operating an electric load.