JP2010267724A - Electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic device that accurately executes temperature detection of heat-generating components with excellent responsiveness so as to previously prevent breakage or the like by sensing heat generation because of an overcurrent or the like. <P>SOLUTION: The electronic device has a circuit board 1 mounted with heat-generating components 2 and a heat-sensitive element 3 for detecting the temperature of the heat-generating components 2. The circuit board 1 is formed with a conductor pattern 4 exclusively used for heat transfer that extends from the heat-generating component mounting part to the periphery of the heat-sensitive element 3 and is not electrically connected with components other than the heat-generating components 2, in order to be used for heat transfer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electronic apparatus having a circuit board on which a heat generating component and a heat sensitive element for detecting the temperature of the heat generating component are mounted.

  Conventionally, for example, in electronic devices such as automotive electronic devices, household electronic devices, industrial device electronic devices, and medical device electronic devices, a heat generating component such as a transistor through which a large current flows and the temperature of the heat generating component It is known that a heat sensitive element for detecting (overheating) is mounted on a circuit board, and heat generation due to overcurrent or the like is detected to prevent damage to electronic equipment.

  In the electronic apparatus having the above-described configuration, it is known that the thermal element is disposed so as to be close to the heat generating component, and the heat generation of the heat generating component is detected by the thermal element (see, for example, Patent Document 1). In addition, it is known that the thermosensitive element is arranged on the back side of the position where the heat generating component of the circuit board is mounted (see, for example, Patent Document 2). Furthermore, it is known that a heat sensitive element is provided in an electric conduction path composed of a wiring pattern electrically connected to a heat generating component to detect heat generation of the heat generating component (see, for example, Patent Document 3).

JP 2007-31529 A JP-A-6-62525 JP-A-8-32361

  Among the above-described conventional electronic devices, in an electronic device in which a thermal element is arranged so as to be close to a heat-generating component, heat transfer is affected by an air layer existing between the heat-generating component and the heat-sensitive element. In addition to causing a response delay, it is difficult to accurately detect the temperature of the heat generating component.

  In addition, among the above-described conventional electronic devices, in the electronic device having a configuration in which the thermal element is arranged on the back side of the position where the heat generating component of the circuit board is mounted, heat transfer depends on the thermal conductivity of the substrate, In addition to a delay in response to temperature detection, it is difficult to accurately detect the temperature of the heat generating component.

  In addition, among the above-described conventional electronic devices, in the electronic device having the configuration in which the thermal element is provided in the electric conduction path including the wiring pattern electrically connected to the heat-generating component, the wiring pattern constitutes the electric path. Because it is electrically connected to other parts, etc., heat is dissipated through the wiring pattern, and the heat capacity of the wiring pattern also increases, resulting in a delay in response of temperature detection and accurate temperature detection of the heat-generating component. There is a problem that it is difficult to do.

  The present invention has been made in response to the above-described conventional circumstances. The present invention is intended to provide an electronic apparatus capable of detecting the temperature of a heat-generating component with higher accuracy and more responsiveness than in the past.

  The electronic device of the present invention is an electronic device having a circuit board on which a heat generating component and a heat sensitive element for detecting the temperature of the heat generating component are mounted. The heat sensitive element is mounted on the circuit board from the heat generating component mounting portion. And a heat transfer-dedicated conductor pattern for heat transfer that is not electrically connected to components other than the heat-generating component.

  In the electronic device of the present invention having the above-described configuration, the heat transfer dedicated conductor for heat transfer that extends from the heat generating component mounting portion to the periphery of the heat sensitive element and is not electrically connected to the components other than the heat generating component on the circuit board. A pattern is formed. With this heat transfer dedicated conductor pattern, the heat generated in the heat generating component is efficiently and quickly transferred to the heat sensitive element. In addition, since the heat transfer dedicated conductor pattern is not electrically connected to any component other than the heat generating component, heat is not radiated to other electronic components through the wiring pattern. The heat capacity can also be reduced. As a result, the temperature of the heat generating component can be detected accurately and with good responsiveness.

  In the electronic device of the present invention having the above-described configuration, it is preferable that the heat transfer dedicated conductor pattern is provided so as to surround at least half a circumference of the thermal element. As a result, the heat generated in the heat generating component can be transmitted to the heat sensitive element more efficiently and quickly, and the temperature of the heat generating component can be detected more accurately and with high responsiveness.

  As said heat-emitting component, the switching element for switching the electric current supplied to the glow plug for diesel engines can be used. Further, as the switching element, for example, an FET element (field effect transistor element) having a gate electrode terminal, a source electrode terminal, and a drain electrode terminal can be used. Can be configured to be connected. As a result, overheating or the like due to overcurrent of the FET element can be detected accurately and with good responsiveness.

  In the electronic device of the present invention having the above-described configuration, the heat generating component can be configured to include a heat radiating member. In this case, at least a part of the heat sensitive element is disposed to be located below the heat radiating member. It can be. Thus, the heat transmitted from the heat generating component to the heat radiating member can be transmitted to the heat sensitive element, and the temperature of the heat generating component can be detected more accurately and with high responsiveness.

  Moreover, in the electronic device of the present invention having the above configuration, the surface of the heat transfer dedicated conductor pattern is preferably covered with an insulating resin. Thereby, heat radiation from the heat transfer dedicated conductor pattern between the heat generating component and the heat sensitive element can be suppressed to the air, and more heat can be transmitted from the heat generating component to the heat sensitive element. As a result, the temperature of the heat generating component can be detected more accurately and with good responsiveness.

  ADVANTAGE OF THE INVENTION According to this invention, the electronic device which can detect the temperature of a heat-emitting component correctly and with sufficient responsiveness compared with the past can be provided.

The figure which shows typically the principal part structure of the circuit board of the electronic device of one Embodiment of this invention. The figure which shows typically the structure of the AA cross section of the circuit board of FIG. FIG. 2 is a perspective view schematically showing a configuration of a circuit board of the electronic device in FIG. 1. FIG. 6 is a diagram for explaining the operation of the electronic apparatus according to the embodiment. The figure which expands and shows typically the principal part structure of the circuit board of the electronic device of FIG. The figure which shows the result of having measured the temperature difference of the temperature of a heat source, and the temperature of a thermal element. The figure which expands and shows typically the principal part structure of the electronic device of other embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a top view schematically showing a main part configuration of a circuit board constituting an electronic apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram showing an AA surface configuration of the circuit board of FIG. FIG. 3 is a perspective view of the circuit board of FIG. In these drawings, reference numeral 1 denotes a circuit board for constituting an electronic device. The circuit board 1 has a plurality of (four in the present embodiment) FET elements (field effect transistor elements) 2 as heat-generating components. It is installed.

  A thermistor 3 as a heat sensitive element is mounted on the circuit board 1 in the vicinity of one FET element 2 (FET element 2 located in the lower right portion in FIG. 1). Note that a thermistor 3 may be provided for each of the four FET elements 2. Further, as shown in FIG. 1, the circuit board 1 is equipped with a control IC 30 and electronic components such as an operational amplifier 31.

  Each FET element 2 is connected to a metal heat dissipating member 5 formed in a substantially U shape in accordance with the outer peripheral shape of the circuit board 1. The thermistor 3 is disposed below the heat dissipating member 5 so that at least a part of the thermistor 3 is located. As a result, as indicated by a downward arrow H2 in FIG. 3, the heat once transferred from the FET element 2 to the heat radiating member 5 is transferred to the thermistor 3 by radiation, and the temperature of the FET element 2 is more accurately measured by the thermistor 3. And it is the structure which can detect rapidly.

  In the present embodiment, the circuit board 1 constitutes a control unit that performs a switching operation for supplying a current to a glow plug of a diesel engine. For this reason, the number of FET elements 2 (four in this embodiment) according to the number of cylinders of the automobile is provided. And the said circuit board 1 is accommodated in a case etc., and is arrange | positioned in the engine room etc. of a motor vehicle as a control unit.

  As shown in FIG. 4, a control signal from an engine control unit (ECU) 50 mounted on the vehicle is input to the control IC 30 of this control unit, and the FET element 2 is switched based on this control signal, and the battery The current supply from 51 to the glow plug 52 is controlled.

  In the control unit including the circuit board 1, it is assumed that an excessive current flows through the FET element 2 due to a trouble such as an engine. When a temperature increase of the FET element 2 is detected by the thermal element 3 due to overcurrent or the like, the operational signal is driven to forcibly stop the control signal input from the ECU 50 to the control IC 30, and the FET element 2. To prevent overheating.

  In the above case, it is necessary to detect the temperature rise due to the overcurrent of the FET element 2 accurately and quickly by the thermistor 3. In the present embodiment, as shown in FIG. 5, a heat transfer dedicated conductor pattern 4 is formed between the FET element 2 and the thermistor 3 on the circuit board 1. Heat transfer from 2 to the thermistor 3 is promoted. As a result, overheating due to overcurrent of the FET element 2 can be detected accurately and quickly. Hereinafter, the configuration of the heat transfer dedicated conductor pattern 4 will be described in detail with reference to FIG.

  As shown in FIG. 5, in the present embodiment, the FET element 2 is a vertical component, and the FET element 2 includes a source electrode terminal 20, a drain electrode terminal 21, a gate electrode so as to extend below the FET element 2. A terminal 22 is provided. On the other hand, on the circuit board 1, a heat transfer dedicated conductor pattern 4 extending from the mounting portion of the FET element 2 to the periphery of the thermistor 3 and not electrically connected to components other than the FET element 2 is formed. In other words, the heat transfer dedicated conductor pattern 4 is formed only for the purpose of transferring the heat generated in the FET element 2 to the thermistor 3, and is therefore electrically connected to components other than the FET element 2. It is not connected, and the current does not flow through the conductor pattern 4 for heat transfer.

  The heat transfer dedicated conductor pattern 4 is made of copper having a high thermal conductivity, as is the case with other conductor patterns (not shown) for configuring an electrical path formed on the circuit board 1. Further, the surface of the dedicated heat transfer conductor pattern 4 is made of an insulating resin (not shown) in the same manner as a conductor pattern (not shown) serving as another electrical path formed on the circuit board 1. Covered. Thus, by covering the surface of the heat transfer dedicated conductor pattern 4 with an insulating resin, heat can be prevented from escaping due to heat radiation in the air in the heat transfer path from the FET element 2 to the thermistor 3. .

  In the present embodiment, the heat transfer dedicated conductor pattern 4 is electrically connected to the drain electrode terminal 21 of the FET element 2. In addition, the electrical connection of the drain of the FET element 2 is performed by connecting the electrode 23 provided on the upper side of the FET element 2 to the metal heat radiating member 5 as shown in FIGS. Yes.

  As shown in FIG. 5, the heat transfer dedicated conductor pattern 4 is formed so as to surround the three sides of the four sides of the substantially rectangular thermistor 3. It is preferable that the heat transfer dedicated conductor pattern 4 is formed so as to surround at least half (for example, two sides) of the periphery of the substantially rectangular thermistor 3. It is necessary to provide a conductor pattern (not shown) for connecting the thermistor 3 to the electric circuit in the vicinity of the thermistor 3 on the substrate 1. For this reason, it is necessary to form the heat transfer dedicated conductor pattern 4 around the thermistor 3 while leaving a portion for drawing out the conductor pattern. Therefore, in this embodiment, the heat transfer dedicated conductor pattern 4 is formed so as to surround the three sides of the four sides of the thermistor 3, and the remaining one side (in the example shown in FIG. A conductor pattern (not shown) for connecting the thermistor 3 to an electric circuit is formed in a portion on the lower side of 3.

  From the viewpoint of efficiently transferring heat from the FET element 2 to the thermistor 3, it is preferable that the heat transfer dedicated conductor pattern 4 is provided close to the thermistor 3. However, in consideration of the possibility of an electrical short circuit, the distance between the heat transfer dedicated conductor pattern 4 and the thermistor 3 (indicated by the symbol D in FIG. 5) is preferably about 0.2 mm. .

  Further, the heat transfer amount increases as the line width (indicated by the symbol W in FIG. 5) of the conductor pattern 4 exclusively for heat transfer increases. However, if the line width of the heat transfer dedicated conductor pattern 4 is too large, the amount of heat dissipated into the air during heat transfer from the FET element 2 to the thermistor 3 increases, and heat transfer to the thermistor 3 is obstructed. become. For this reason, it is preferable that the line width of the conductor pattern 4 for heat transfer is about 1 mm.

  Further, when the total length of the heat transfer dedicated conductor pattern 4 is increased, the amount of heat radiation described above increases, and heat capacity increases, heat transfer delay, and the like occur. For this reason, it is preferable to arrange the FET element 2 and the thermistor 3 close to each other so that the total length of the heat transfer dedicated conductor pattern 4 is shortened. In FIG. 5, the black circular mark indicates the heat generating portion of the FET element 2, and the arrow indicates the heat transfer path from the heat generating portion. Examples of such heat generating parts include the drain terminal of the FET element, the back surface GND of the power supply IC, and the like. In addition, the heat flow from the heat transfer dedicated conductor pattern 4 to the thermistor 3 is indicated by an arrow H1 in FIG.

  FIG. 6 is a graph showing the results of measuring the temperature difference between the FET element 2 as the heat source and the thermistor 3 with the vertical axis representing the temperature difference (Δ ° C.) and the horizontal axis representing the time. In this measurement, the distance between the FET element 2 and the thermistor 3 was 3 mm, and the difference between the temperature of the FET element 2 and the temperature of the thermistor 3 when the temperature of the FET element 2 was raised to 170 ° C. was measured.

  In FIG. 6, a curve A shows the result of examining the temperature difference in the case of the present embodiment, and a curve B shows the temperature difference when the heat transfer dedicated conductor pattern 4 is not provided as a comparative example. As shown in the figure, in this embodiment, the temperature difference between the FET element 2 and the thermistor 3 could be within 10 ° C. On the other hand, in the case of the comparative example without the heat transfer dedicated conductor pattern 4, the temperature difference between the FET element 2 and the thermistor 3 was 20 ° C. or more. As is clear from this result, in the present embodiment including the heat transfer dedicated conductor pattern 4, heat transfer from the FET element 2 to the thermistor 3 can be promoted by the heat transfer dedicated conductor pattern 4 accurately and quickly. Overheating or the like due to overcurrent of the FET element 2 can be detected.

  In the above embodiment, the case where the heat generating component is the vertical FET element 2 has been described. However, the heat generating component is not limited to the vertical FET element 2 and can be similarly applied to any heat generating component. . For example, as shown in FIG. 7, even if the heat generating component is a surface mounting component 200 mounted on the circuit board 1, it can be similarly applied. In FIG. 7, black circle marks indicate the heat generating portion of the surface mount component 200, and arrows indicate the heat transfer path from the heat generating portion. Examples of such heat generating parts include the drain terminal of the FET element, the back surface GND of the power supply IC, and the like.

  In the above embodiment, the case where the present invention is applied to a control unit for supplying power by switching current to a glow plug of a diesel engine has been described. However, the present invention is not limited to such an embodiment, and can be similarly applied to any electronic device.

  DESCRIPTION OF SYMBOLS 1 ... Circuit board, 2 ... FET element, 3 ... Thermistor, 4 ... Heat transfer exclusive conductor pattern, 5 ... Heat dissipation member.

Claims (6)

In an electronic device having a circuit board on which a heat generating component and a heat sensitive element for detecting the temperature of the heat generating component are mounted,
Formed on the circuit board is a dedicated heat transfer conductor pattern for heat transfer that extends from the heat generating component mounting portion to the periphery of the heat sensitive element and is not electrically connected to components other than the heat generating component. Features electronic equipment. The electronic device according to claim 1,
The electronic apparatus according to claim 1, wherein the heat transfer dedicated conductor pattern is provided so as to surround at least half a circumference of the thermal element. The electronic device according to claim 1 or 2,
The electronic device, wherein the heat generating component is a switching element for switching a current supplied to a glow plug for a diesel engine. The electronic device according to any one of claims 1 to 3,
The electronic device, wherein the switching element is composed of an FET having a gate electrode terminal, a source electrode terminal, and a drain electrode terminal, and the heat transfer dedicated conductor pattern is connected to the drain electrode terminal. In the electronic device of any one of Claims 1-4,
The electronic device, wherein the heat generating component includes a heat radiating member, and at least a part of the heat sensitive element is disposed below the heat radiating member. In the electronic device of any one of Claims 1-5,
An electronic apparatus, wherein a surface of the heat transfer dedicated conductor pattern is covered with an insulating resin.

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