JP2015097459A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase heat resistance while arranging a plurality of heat generating elements which perform parallel operation to fulfill the same function and a low heat resistance element on the same substrate.SOLUTION: A semiconductor device is built on a vehicle and comprises a plurality of heat generating elements parallely connected with each other, a low heat-resistance element and control means for controlling driving of the heat generating elements. The semiconductor device includes: a heat insulation part for thermally insulating a first element group having the low heat-resistance element and some heat generating elements and a second element group having heat generating element except some heat generating elements included in the first element group; and acquisition means for acquiring physical amounts using temperatures of the heat generating elements and the low heat-resistance element as dependent variables. The control means changes a combination of the heat generation elements to be energized based on the physical amounts acquired by the acquisition means in a manner such that a temperature of each of the heat generating elements and the low heat -resistance element does not exceed a heatproof temperature of each of the heat generating elements and the low heat-resistance element.

Description

  The present invention relates to a semiconductor device in which a heating element and a low heat resistance element are mounted in proximity.

  In recent years, electronic devices have been downsized. For example, in an engine ECU that is disposed in a vehicle and controls driving of an engine, a control system element for power supply to various sensors and communication with other ECUs and a load such as fuel pumping and injection are operated. These power system elements are mounted on the same substrate to achieve downsizing of the entire substrate.

  By the way, while many elements constituting the control system circuit have low heat resistance, many elements constituting the power system circuit include a large amount of self-heating. For this reason, when these elements are mounted on the same substrate, there is a possibility that heat interference from the heat generating element to the low heat resistance element may occur. That is, miniaturization and heat resistance are in a trade-off relationship.

  Patent Document 1 proposes a configuration having a blocking hole that is a portion having a lower thermal conductivity than the heat dissipation plate so as to separate the heat generating element connected to the heat dissipation plate via the printed wiring board and the small signal element. ing.

Japanese Patent Laid-Open No. 7-32423

  However, in the configuration of Patent Document 1, since the heat generating element is isolated by the blocking hole, the volume of the heat radiation destination is reduced. For this reason, the heat dissipation rate cannot catch up with the heat generation rate, and the temperature of the heating element may reach the heat resistance temperature or more.

  The present invention has been made in view of the above-mentioned problems, and has heat resistance while arranging a plurality of heating elements operating in parallel to exhibit the same function and low heat resistance elements on the same substrate. It aims to improve.

  The invention disclosed herein employs the following technical means to achieve the above object. Note that the reference numerals in parentheses described in the claims and in this section indicate a corresponding relationship with specific means described in the embodiments described later as one aspect, and limit the technical scope of the invention. Not what you want.

  To achieve the above object, the present invention provides a plurality of heating elements (20) mounted on a vehicle and connected in parallel to each other, a low heat resistance element (30) having a lower heat resistance temperature than the heating elements, and a heating element. And a control device (40) for controlling driving of the heat generating element, and a first device having the low heat resistant element and a part of the heat generating element (21). A heat insulating portion (10b, 310) that thermally separates the element group (A) from the second element group (B) having the heating elements (22) excluding the heating elements included in the first element group; And acquisition means (700, 800) for acquiring a physical quantity having the temperature of the low heat resistance element as a dependent variable, and the control means is based on the physical quantity acquired by the acquisition means, and the temperature of the heating element and the low heat resistance element. Exceeds the respective heat resistance temperature In odd, it is characterized by switching the combination of the heating elements to be energized.

  According to this, the elements mounted on the substrate are separated into a first element group having some heating elements and low heat resistance elements and a second element group having the remaining heating elements, and thermally Blocked. For this reason, the number of heat generating elements that thermally interfere with the low heat resistance elements can be reduced.

  In addition, the control means switches the combination of the heating elements to be energized according to the physical quantity that affects the temperature of the heating element and the low heat resistance element acquired by the acquisition means. That is, the heating element to be energized is selected according to the ambient temperature and the temperatures of the low heat resistance element and the heating element. For this reason, it is possible to prevent the temperatures of the low heat resistance element and the heating element itself from reaching their respective heat resistance temperatures.

It is a figure which shows schematic structure of the semiconductor device which concerns on 1st Embodiment, and is a cross-sectional perspective view which follows the II line | wire in FIG. It is a top view which shows schematic structure of the element mounted in the board | substrate and the board | substrate. It is a figure which shows the circuit structure of a semiconductor device. It is a flowchart which shows operation | movement of the heat generating element which an acquisition means and a control part perform. 10 is a timing chart showing the operation of a heat generating element in Modification 1. It is a figure which shows the circuit structure of the semiconductor device which concerns on 2nd Embodiment. It is a cross-sectional perspective view which shows schematic structure of the semiconductor device which concerns on other embodiment. It is a cross-sectional perspective view which shows schematic structure of the semiconductor device which concerns on other embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same reference numerals are given to the same or equivalent parts.

(First embodiment)
First, a schematic configuration of the semiconductor device according to the present embodiment will be described with reference to FIGS.

  The semiconductor device according to the present embodiment is, for example, an engine ECU that controls a motor and an actuator in an engine room of a vehicle.

  As shown in FIGS. 1 and 2, the semiconductor device 100 includes a substrate 10, two heating elements 21 and 22 that generate heat by driving (collectively referred to as a heating element 20), and a low heat resistance temperature lower than that of the heating element 20. And a heat-resistant element 30. For example, as shown in FIG. 3, the semiconductor device 100 is a circuit including a general boosting choke converter, and includes a control unit 40 that controls driving of the heating element 20. The control unit 40 corresponds to the control means in the claims.

  The substrate 10 is a generally known printed circuit board. On one surface 10a of the substrate 10, the heating element 20 and the low heat resistance element 30 are mounted, and the choke coil 200 is also mounted. In addition, a through hole 10 b is formed in the substrate 10. The through hole 10b is formed so as to thermally separate the heating element 21 and the heating element 22. Thereby, as shown in FIGS. 1 and 2, each of the elements 21, 22, 30 is separated from the first element group A including the heating element 21 and the low heat resistance element 30, the heating element 22, And the second element group B including the choke coil 200.

  As shown in FIG. 3, the heating elements 21 and 22 are switching elements that control the current flowing through the choke coil 200, and are configured by MOSFETs. The heating elements 21 and 22 are the same elements and are connected in parallel to each other. Therefore, when at least one of the heating elements 21 and 22 operates, the semiconductor device 100 functions as a boost choke converter. When the heating elements 21 and 22 transition from on to off, an electromotive force is generated by self-induction of the choke coil 200, and the electromotive force of the choke coil 200 is applied to the capacitor 500 in addition to the voltage of the battery 400. Since the heating elements 21 and 22 are repeatedly turned on and off at a very short cycle, they self-heat with the energization resistance and the switching loss. As described above, the heating elements 21 and 22 in the present embodiment are disposed adjacent to each other through the through hole 10b. In other words, the heating element 21 and the heating element 22 are thermally separated by the through hole 10b. As shown in FIG. 2, the heating element 22 forms a second element group B together with the choke coil 200.

  The low heat resistance element 30 is an integrated circuit such as ASIC or FPGA, for example, and is responsible for communication and control with other ECUs and various sensors. In general, such an integrated circuit has a lower heat resistant temperature than a switching element. That is, the low heat resistant element 30 has a lower heat resistant temperature than the heat generating element 20. In the present embodiment, the low heat resistance element 30 and the heating element 21 are mounted on the substrate 10 adjacent to each other. The low heat resistance elements 30 constitute a first element group A together with the adjacent heating elements 21.

  The control unit 40 controls on / off of a switching element as the heating element 20. The control unit 40 in this embodiment is connected to a temperature acquisition unit 700 and a frequency acquisition unit 800 as acquisition means. The temperature acquisition unit 700 is an acquisition unit that acquires the internal temperature of the engine room as a physical quantity. Moreover, the frequency acquisition part 800 is an acquisition means which acquires an accelerator opening, for example as a physical quantity. The frequency acquisition unit 800 acquires the accelerator opening and estimates the fuel injection frequency necessary for traveling, and thus the driving frequency of the heating element 20. Note that the heat generation amount of the heating element 20 increases as the driving frequency of the heating element 20 increases. The control unit 40 switches the combination of the heating elements 21 and 22 to be energized based on the internal temperature of the engine room acquired by the acquisition means 700 and 800 and the driving frequency of the heating elements. In this way, the control unit 40 controls the heating element 20 so that the temperatures of the heating element 20 and the low heat resistance element 30 do not exceed the respective heat resistance temperatures. The control unit 40 may be integrated with the low heat resistance element 30 described above.

  As shown in FIG. 1, the substrate 10, the heating element 20, the low heat resistance element 30, and the choke coil 200 mounted on the substrate 10 are accommodated in a housing 300. The housing 300 has a ventilation hole 310 through which air can pass at a position corresponding to the through hole 10 b of the substrate 10. The vent hole 310 has a hollow column shape, and its side wall 310 a is formed so as to penetrate the through hole 10 b of the substrate 10. In the present embodiment, the vent hole 310 and the through hole 10b of the substrate 10 correspond to a heat insulating portion described in the claims.

  Next, with reference to FIG. 4, the concrete control method and effect which the control part 40 performs with respect to the heat generating element 20 are demonstrated.

  First, an outline of the control method will be described.

  First, as shown in FIG. 4, the acquisition unit executes step S1. Step S1 is a step in which the temperature acquisition unit 700 acquires the internal temperature T of the engine room. The temperature acquisition unit 700 includes a temperature sensor installed in the engine room, and acquires an internal temperature T in response to a signal from the temperature sensor. Then, the temperature acquisition unit 700 outputs the acquired internal temperature T to the control unit 40.

  Next, the acquisition unit executes step S2. Step S <b> 2 is a step in which the frequency acquisition unit 800 acquires the drive frequency f required for the heating element 20. The frequency acquisition unit 800 includes, for example, a rotation angle sensor, acquires the accelerator opening from the rotation angle sensor, and estimates the fuel injection frequency necessary for traveling. Further, the frequency acquisition unit 800 estimates the drive frequency of the heat generating element 20 from the fuel injection frequency. Thus, the frequency acquisition unit 800 acquires the drive frequency f of the heating element 20. Then, the frequency acquisition unit 800 outputs the acquired drive frequency f to the control unit 40.

  Next, the control unit 40 executes step S3. In step S3, the control unit 40 compares the engine room internal temperature T with the engine room allowable temperature τ. The allowable temperature τ is a preset temperature. The allowable temperature τ is set as a temperature at which the temperature of the low heat resistant element 30 may exceed the heat resistant temperature when the temperature T in the engine room exceeds the temperature τ.

  If the internal temperature T of the engine room is equal to or higher than the allowable temperature τ in step S3, that is, if T ≧ τ, the process proceeds to step S4. On the other hand, if T <τ, the process proceeds to step S5.

  Steps S4 and S5 are both steps in which the controller 40 compares the drive frequency f of the heat generating element 20 acquired with the allowable frequency ν. The allowable frequency ν is a preset frequency. The allowable frequency ν is set as a frequency at which when the driving frequency f of the heat generating element 20 exceeds the frequency ν, the temperature of the heat generating element 20 may exceed the heat resistant temperature due to self-heating of the heat generating element 20.

  If T ≧ τ and f ≧ ν, that is, if YES is determined in step S3 and YES is determined in step S4, the process proceeds to step S6. If T <τ and f <ν, that is, if NO is determined in step S3 and NO is determined in step S4, the process proceeds to step S6. Step S6 is a step in which the control unit 40 operates both the heating elements 21 and 22. The operation of the heating element 20 in step S6 is such that the heating elements 21 and 22 operate in parallel. For this reason, compared with the case where each heating element 21 and 22 operate | moves independently, the energization resistance of the heating element 20 can be made small. Therefore, in the operation in step S6, the amount of self-heating of the heating element 20 can be minimized.

  If T ≧ τ and f <ν, that is, if YES is determined in step S3 and NO is determined in step S4, the process proceeds to step S7. Step S <b> 7 is a step in which the control unit 40 stops the operation of the heating element 21 and operates the heating element 22. In the operation of the heating element 20 in step S7, only the heating element 22 operates. For this reason, among the element groups A and B thermally separated by the air vent 310 and the through hole 10b, the heat generation amount of the first element group A is smaller than the heat generation amount of the second element group B. That is, the operation in step S <b> 7 is an operation for suppressing thermal interference with the low heat resistance element 30.

  If T <τ and f ≧ ν, that is, if NO is determined in step S3 and NO is determined in step S4, the process proceeds to step S8. Step S <b> 8 is a step in which the control unit 40 stops the operation of the heating element 22 and activates the heating element 21. In the operation of the heating element 20 in step S8, only the heating element 21 operates. For this reason, among the element groups A and B thermally separated by the air vent 310 and the through hole 10b, the heat generation amount of the second element group B is smaller than the heat generation amount of the first element group A. That is, the operation in step S8 is an operation that prioritizes that the temperature of the heat generating element 22 does not exceed the heat resistant temperature by self-heating rather than thermal interference with the low heat resistant element 30. In other words, in a situation where the low heat resistance element 30 is sufficiently cooled, the operation of increasing the burden on the heating element 21 as compared to the heating element 22 as the distribution of the heat generation amount by the heating element 20.

  Next, the operation in a specific traveling state will be exemplified below.

  As an example, a case where a vehicle equipped with the semiconductor device 100 according to the present embodiment travels in an urban area will be described.

  When traveling in an urban area, the engine output may be smaller than when traveling on a highway. For this reason, the drive frequency f of the heat generating element 20 becomes smaller than the allowable frequency ν. On the other hand, since the vehicle speed is smaller than traveling on an expressway, the air cooling effect in the engine room is also reduced. Therefore, the internal temperature T of the engine room may be equal to or higher than the allowable temperature τ. In such a case, since T ≧ τ and f <ν, the control unit 40 instructs the heating element 20 to execute step S7 via steps S3 and S4. In step S <b> 7, thermal interference from the heating element 20 can be suppressed with respect to the low heat resistance element 30 that cannot expect the air cooling effect. Therefore, it is possible to suppress the low heat resistant element 30 from reaching the heat resistant temperature.

  Note that the operation through step S7 as described above can be applied even when the vehicle is in an idle state.

  As another example, a case where a vehicle equipped with the semiconductor device 100 according to the present embodiment travels on a highway will be described.

  When traveling on an expressway, the vehicle speed is higher than traveling on an urban area. For this reason, the air cooling effect in the engine room is sufficiently obtained, and the internal temperature T of the engine room becomes smaller than the allowable temperature τ. On the other hand, the output of the engine is larger than that of traveling in an urban area. Therefore, the driving frequency f of the heat generating element 20 may be equal to or higher than the allowable frequency ν. In such a case, since T <τ and f ≧ ν, the control unit 40 instructs the heating element 20 to execute step S8 via steps S3 and S5. In step S8, it is possible to increase the burden on the heat generating elements 21 belonging to the first element group A together with the low heat resistant elements 30 that can be expected to have an air cooling effect, and to prevent the heat generating elements 22 from reaching the heat resistant temperature due to self-heating.

  Note that the operation through step S8 as described above can be applied even when the vehicle travels uphill.

  Next, functions and effects of the heat insulating portion, that is, the vent hole 310 of the housing 300 and the through hole 10b of the substrate 10 will be described.

  As described above, the vent hole 310 is formed through the through hole 10 b formed in the substrate 10. Since the through hole 10b is formed in the substrate 10, the heat transfer path between the first element group A and the second element group B can be made longer than when the through hole 10b is not formed. it can. Further, since the air vent 310 is interposed between the first element group A and the second element group B, heat conduction due to conduction and radiation between the first element group A and the second element group B is also suppressed. can do.

  In particular, in the present embodiment, air flows through the air holes 310 and heat transfer by convection acts on the air holes 310, so that the inside of the holes is filled with the same material as the housing 300. Heat insulation performance can be improved.

(Modification 1)
In the first embodiment, an example in which both the heating elements 21 and 22 are activated in step S6 has been described. In addition, in Step S7 or Step S8, an example is shown in which one of the heating elements 21 and 22 is activated and the other is stopped. FIG. 5 is a timing chart showing the operation of the heating elements 21 and 22 in time series. In the time domain I in FIG. 5, step S6 in which both the heating elements 21 and 22 are activated is shown. In time region II, step S7 in which the heating element 21 is stopped and the heating element 22 is activated is shown. In time region III, step S8 is shown in which the heating element 21 is activated and the heating element 22 is stopped.

  However, unlike the time domain II and time domain III described above, it is not necessary that the other heating element 20 is completely stopped when one heating element 20 is operating. As shown in the time region VI, in step S7, the heating element 21 to be stopped can be operated for a shorter time than the heating element 22. Alternatively, as shown in the time region V, the heating element 22 to be stopped can be operated for a shorter time than the heating element 21 in step S8.

  In this manner, the heating element 20 that has been stopped in the first embodiment can be operated for a shorter time than the heating element 20 that is being operated. Thereby, the balance of the self-heating amount by the heating elements 21 and 22 can be adjusted in more detail.

(Second Embodiment)
In 1st Embodiment and the modification 1, although the semiconductor device 100 showed the example which comprises a pressure | voltage rise choke converter, it is not limited to this example. For example, as shown in FIG. 6, the present invention can also be applied to a constant current circuit used for a fuel injection injector or the like.

  Also in the present embodiment, the heating element 20 is a switching element. The control unit 40 causes a constant current to flow through the coil 900 by outputting a signal subjected to pulse width modulation (PWM) control to the heating element 20. The fuel injection amount by the injector is adjusted according to the current value.

  Similar to the first embodiment, the semiconductor device 100 has two switching elements as the heat generating elements 20, and these are connected in parallel to each other. The combination of the heat generating elements 21 and 22 to be energized is appropriately switched based on the physical quantity such as the internal temperature of the engine room and the driving frequency of the heat generating element 20.

  Thereby, there can exist an effect similar to 1st Embodiment. That is, it is possible to adjust the balance of the heat generation amounts of the heating elements 21 and 22 so that the temperature of the heating element 20 and the low heat resistance element 30 does not exceed the respective heat resistance temperatures.

(Other embodiments)
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In each of the above-described embodiments, the example in which the internal temperature T of the engine room is acquired by the temperature acquisition unit 700 including the temperature sensor has been described. However, the internal temperature T has a database of the relationship between the vehicle speed and the internal temperature T in advance. It may be estimated from the vehicle speed.

  Moreover, although the example which estimates the drive frequency f of the heat generating element 20 from the accelerator opening degree by the frequency acquisition part 800 was shown, the drive frequency f can also be estimated from an engine speed.

  In each of the above-described embodiments, the example in which the two switching elements that are the heating elements 20 are configured from the same element has been described. However, it is not necessary that the elements are completely the same, and an element that functions as a switching element. The present invention can be applied if it exists. Further, the type of the heating element 20 is not limited to the switching element.

  Further, in each of the above-described embodiments, the example in which the heat generating element 20 is configured by the two heat generating elements 21 and 22 has been described, but the present invention may be applied even in a configuration in which three or more heat generating elements 20 are connected in parallel. The invention can be applied.

  Further, in each of the above-described embodiments, as shown in FIG. 1, an example in which the heat insulating portion is configured by the through hole 10b of the substrate 10 and the hollow columnar vent hole 310 is shown, but the present invention is not limited to this example. Absent. For example, as shown in FIG. 7, a heat insulating wall 320 formed integrally with the housing 300 can penetrate the through hole 10 b of the substrate 10. In such a configuration, as in the case of the first embodiment, since the through hole 10b is formed in the substrate 10, the heat transfer path between the first element group A and the second element group B is It can be made longer than when the through-hole 10b is not formed. Further, since the heat insulating wall 320 is interposed between the first element group A and the second element group B, heat transfer due to radiation between the first element group A and the second element group B is also suppressed. Can do.

  After that, as in the first embodiment, the combination of the heat generating elements 21 and 22 to be energized is appropriately switched based on the physical quantity having the temperature of the heat generating element 20 and the low heat resistant element 30 as a dependent variable. Yes. Thereby, there can exist an effect similar to 1st Embodiment.

  Further, as illustrated in FIG. 8, in a configuration in which the substrate 10 does not have the through hole 10 b, a configuration in which the casing 300 includes a heat insulating wall 330 formed so as to contact the substrate 10 may be used. In such a configuration, since the heat insulating wall 330 is interposed between the first element group A and the second element group B, heat transfer by radiation between the first element group A and the second element group B is performed. Can also be suppressed.

DESCRIPTION OF SYMBOLS 100 ... Semiconductor device 10 ... Board | substrate 10b ... Through-hole 20 ... Heating element 30 ... Low heat-resistant element 40 ... Control part 200 ... Choke coil 300 ... Case 310- ..Ventilation holes

Claims (6)

Mounted on the vehicle,
A plurality of heating elements (20) connected in parallel to each other; a low heat resistance element (30) having a lower heat resistance temperature than the heat generation elements; and a substrate (10) on which the heat generation elements and the low heat resistance elements are mounted. A control means (40) for controlling the driving of the heating element,
A first element group (A) having the low heat resistance element and a part of the heating elements (21), and a second element group having the heating elements (22) excluding the heating elements included in the first element group. (B) and a heat insulating part (10b, 310) that thermally separates
Obtaining means (700, 800) for obtaining a physical quantity having the temperature of the heat generating element and the low heat resistance element as a dependent variable;
The control means switches the combination of the heating elements to be energized based on the physical quantity acquired by the acquisition means so that the temperatures of the heating elements and the low heat resistance elements do not exceed the respective heat resistance temperatures. A semiconductor device characterized by the above. The heating element, the low heat resistance element and the substrate are arranged in an engine room of the vehicle,
The acquisition means acquires the internal temperature T of the engine room and the driving frequency f of the heating element as the physical quantity,
The control means, for the preset allowable temperature τ of the engine room and the allowable frequency ν of the heating element,
When T ≧ τ and f ≧ ν, or T <τ and f <ν, the heating elements of the first element group and the heating elements of the second element group are operated together,
When T ≧ and f <ν, the heating elements of the second element group are operated, and the heating elements of the first element group are operated for a shorter time than the heating elements of the second element group. Or stop,
When T <τ and f ≧ ν, the heating element of the first element group is operated, and the heating element of the second element group is operated for a shorter time than the heating element of the first element group. The semiconductor device according to claim 1, wherein the semiconductor device is stopped or stopped.   The semiconductor device according to claim 2, wherein the internal temperature T of the engine room is a value acquired by a temperature sensor or a value estimated based on a vehicle speed.   4. The semiconductor device according to claim 2, wherein the drive frequency f of the heat generating element is a value estimated based on an engine speed or an accelerator opening.   The semiconductor device according to claim 1, wherein the heat insulating portion is formed through the substrate.   The semiconductor device according to claim 5, wherein the heat insulating portion has a hollow column shape.

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