JP3936667B2 - Electronic control unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic control device. In particular, it relates to an optimal shape of the substrate heat sink under the power element. Further, the present invention relates to an electronic control device that controls a vehicle engine, and more particularly, to an electronic control device having a structure in which a power element is mounted on a ceramic substrate.
[0002]
[Prior art]
Conventionally, when a ceramic substrate is bonded to a heat sink of a metal plate with an adhesive such as a silicon adhesive, a groove is provided in the metal plate to avoid the formation of voids in the adhesive between the substrate and the metal plate. The metal plate to be used has a structure that can be in close contact with the ceramic substrate.
[0003]
[Patent Document 1]
JP 2002-315358 A [0004]
[Problems to be solved by the invention]
Depending on the arrangement of components on the board, a groove recess may come to a portion that contacts the power element. When the concave portion of the groove comes under the power element, there is a problem that heat conduction from the power element to the metal plate is deteriorated and the temperature rise of the power element is increased.
[0005]
The position of the groove of the metal plate was considered so as not to generate a void in the adhesive, but the positional relationship with the power element on the ceramic substrate was not particularly considered.
[0006]
An object of the present invention is to provide an electronic control device capable of cooling a power element more efficiently.
[0007]
[Means for Solving the Problems]
By providing a groove so that the convex part of the metal plate comes to the lower part of the power element mounted on the board, the thermal resistance between the power element and the metal plate can be reduced, and the temperature of the power element rises Can be suppressed.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the first embodiment will be described by taking an electronically controlled throttle device as an example.
[0009]
FIG. 5 shows a structural diagram of an electronically controlled throttle device to which the structure of the embodiment is applied.
[0010]
The main purpose of this device is to detect the opening degree of the throttle valve 18 by the opening degree sensor 17, process the signal by the throttle control module on the throttle control device board 1, and supply current to the accompanying motor 14. The power is transmitted to the throttle valve shaft 19 via the gear 15 attached to the motor 14 to rotate the throttle valve 18 to obtain a predetermined opening degree.
[0011]
The throttle control device substrate 1 is bonded to an aluminum plate 2 serving as a heat sink with a silicon adhesive.
[0012]
FIG. 6 is a circuit configuration of the throttle control device substrate 1. Power is input from the battery 104 supplied from the battery power supply of the vehicle, and a target opening signal output from the engine control module 105 in the vehicle is input to the microprocessor 102 via the serial communication circuit 106. The microprocessor 102 outputs a signal to the motor driver IC 103 in the throttle control module while performing feedback based on the slot opening sensor value output from the throttle opening sensor 17. In response to the signal, the motor driver IC 103 receives power supply from the battery line 104 and supplies a current value to be supplied to the motor 14.
[0013]
The drive current to the motor 14 in the throttle control module normally reaches 1.5A and reaches a peak of 5A, and more heat is generated due to the ON resistance of the FET existing in the motor driver IC 103 (in this case, 300 mΩ). Normally, 1W, and when the throttle valve is moved at a high speed, a loss of 5W instantaneously occurs, and this all generates heat.
[0014]
Next, the heat dissipation structure will be described.
[0015]
FIG. 1 is a sectional view of the heat dissipation structure, and FIG. 2 is a plan view.
[0016]
The throttle control module has a microprocessor 102, a motor driver IC 103, and electronic components (IC, resistor, capacitor, etc.) not described here mounted on a ceramic substrate. Glued with.
[0017]
Of the components mounted on the throttle control device board 1, the motor driver IC 103 generates a large amount of heat, and the key to the heat dissipation structure of the throttle control module is to improve the heat dissipation of the IC and suppress the temperature rise.
[0018]
In FIG. 1, the motor driver IC 103 is connected to the throttle control device board 1 by the solder 22, and the heat generated by the motor driver IC 103 is transmitted to the throttle control device board 1 through the solder 22, and It travels in the vertical direction and then through the silicon adhesive 23 to the aluminum plate 2.
[0019]
As shown in FIG. 1, the aluminum plate 2 is also made of a silicone adhesive to the resin gear cover 3 and radiates heat from the resin case to the atmosphere.
[0020]
Here, looking at the thermal conductivity of each part that becomes a heat path, the throttle control device substrate 1 is 25 W / m · k, the aluminum plate 2 is 220 W / m · k, and the solder 22 is 33 W / m · k. The silicon adhesive 23 is 0.29 W / m · k, and the thermal conductivity of the silicon adhesive 23 is smaller than that of the throttle control device substrate 1 and the aluminum plate 2. It can be seen that it is important to reduce the thermal resistance of the adhesive 23 portion.
[0021]
In addition, when comparing the thermal conductivity of silicon adhesive and air, the thermal conductivity of air is 0.024 W / m · k compared to 0.29 W / m · k for silicon adhesive 23, which is higher than that of silicon adhesive. It becomes even smaller.
[0022]
Therefore, in bonding the throttle control device substrate 1 and the aluminum plate 2, it is important to reduce the thickness of the silicon adhesive 23 so as not to create a void that becomes an air layer therein.
[0023]
As a method of not creating a void in the silicon adhesive 23, there is a method of forming a groove in the aluminum plate 2. When the throttle control device substrate 1 and the aluminum plate 2 are bonded, the adhesive is applied to the aluminum plate 2, and then the throttle control device substrate 1 is placed on the throttle control device substrate 1. The thickness of the adhesive 23 can be reduced at 25 portions that flow to 24 and become convex portions.
[0024]
Next, the positions of the recess 24 of the aluminum plate 2 and the motor driver IC 103 will be described. As described above, the heat generated by the motor driver IC 103 is 5 W instantaneously compared to 1 W on average.
[0025]
Considering the rated junction temperature of the motor driver IC 103, it is necessary to suppress the temperature rise within a certain temperature including instantaneous heat generation. When considering heat dissipation for the average amount of heat generation, heat dissipation from the aluminum plate 2 to the atmosphere through the gear cover 3 is the most influential part for the temperature rise of the motor driver IC 103, but the temperature for instantaneous heat generation of 5W. Since the rise is as short as about 50 ms, the most significant influence on the temperature rise of the motor driver IC 103 is the heat conduction from the motor driver IC 103 to the aluminum plate 2.
[0026]
In the heat conduction path from the motor driver IC 103 to the aluminum plate 2, the portion from the back surface of the throttle control device substrate 1 through the silicon adhesive 23 to the aluminum plate 2 has the lowest thermal conductivity, and this portion improves heat transfer. It is important to do.
[0027]
In view of the conventional aluminum plate structure from this point, as shown in the sectional view of FIG. 3 and the plan view of FIG. Was dug under.
[0028]
When the temperature difference of each heat transfer portion from the motor driver IC 103 to the aluminum plate 2 is calculated for the conventional aluminum plate 2 shown in FIG. 4 and the aluminum plate shown in FIG. 2, the chip size is 5 mm × 5 mm and the solder 22 The thickness is 0.2 mm, the thickness of the throttle control device substrate 1 is 1 mm, the thickness of the silicon adhesive 23 of the convex portion 25 of the aluminum plate is 0.05 mm, and the thickness of the silicon adhesive of the concave portion 24 of the aluminum plate 2 is 0.3 mm. Suppose that heat is transmitted vertically from the back of the motor driver IC 103. Assuming that the heat generation is constant at 5 W, the temperature difference at the solder 22 portion is 1.2 ° C., the temperature difference at the throttle control device board 1 portion is 8 ° C., and the temperature difference at the silicon adhesive 23 portion is the conventional one shown in FIG. In contrast to the 59.1 ° C. in the structure, in FIG.
[0029]
From this, it can be seen that providing a groove so that the convex portion of the groove of the aluminum plate 2 comes in a portion corresponding to the lower part of the motor driver IC 103 is effective in suppressing the temperature rise of the power element.
[0030]
According to the above, in the electronic control device having a structure in which the ceramic substrate on which the power element is mounted is bonded to the aluminum plate, the groove is formed so that the convex portion of the groove for releasing the adhesive provided on the aluminum plate is disposed under the power element. By providing, the temperature rise of the power element on the substrate can be suppressed.
[0031]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the electronic control apparatus which can perform cooling of a power element more efficiently can be provided.
[Brief description of the drawings]
FIG. 1 is a sectional structural view of an embodiment.
FIG. 2 is a plan structural view of the embodiment.
FIG. 3 is a cross-sectional view of a heat dissipation structure.
FIG. 4 is a plan view of a heat dissipation structure.
FIG. 5 is a structural diagram of a throttle control device to which the embodiment is applied.
FIG. 6 is a circuit configuration diagram of the throttle control device of the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Throttle control board, 2 ... Aluminum plate, 3 ... Gear cover, 7 ... Throttle body, 14 ... Motor, 15 ... Gear, 17 ... Throttle opening sensor, 18 ... Throttle valve, 19 ... Throttle valve shaft, 22 ... Solder, 23 ... silicone adhesive, 102 ... microprocessor, 103 ... motor driver IC.

Claims (5)

A metal plate having an uneven surface shape;
A ceramic substrate bonded via an adhesive on the surface of the metal plate;
An electronic control device having a power element soldered on the ceramic substrate,
The surface of the metal plate has a groove for releasing the adhesive and a convex portion formed by providing the concave groove,
The electronic control device according to claim 1, wherein the power element is disposed at a portion of the ceramic substrate located above the convex portion of the metal plate. A heat sink with an uneven surface shape,
A ceramic substrate bonded via adhesive to the surface of the heat sink;
An electronic control device having a motor driver IC and a microprocessor soldered on the ceramic substrate,
The surface of the heat sink has a groove for releasing the adhesive and a convex portion formed by providing the concave groove,
The motor driver IC is disposed at a portion of the ceramic substrate located above the convex portion of the heat sink, and is not disposed at a portion of the ceramic substrate located above the groove. Electronic control device. An electronic control device used in an electronic control throttle device for controlling the opening of a throttle valve,
The electronic control device includes a heat sink made of metal,
A throttle control device board disposed via an adhesive on the surface of the heat sink,
The surface of the heat sink includes a groove for releasing the adhesive and a convex portion formed by providing the concave groove, so that the surface has an uneven structure. ,
On the throttle control device board, there are a motor driver IC for driving an external motor, an MPU for controlling the motor driver IC, and a serial communication circuit for communicating with the external device. Provided,
The motor driver IC is disposed at a portion of the throttle control device substrate located above the convex portion of the heat sink, and is not disposed at a portion of the throttle control device substrate located above the groove. An electronic control device characterized by that. The electronic control device according to claim 3.
The electronic control device according to claim 1, wherein a thermal conductivity of the adhesive is smaller than a thermal conductivity of the throttle control device substrate and the heat sink. The electronic control device according to claim 3 or 4,
The heat sink is made of aluminum,
The throttle control board is made of ceramic,
An electronic control device, wherein a resistor and a capacitor are mounted on the throttle control device board.

Images