JP5936313B2 - Electronic component mounting structure - Google Patents

Description

  The present invention relates to an electronic component mounting structure in which a substrate on which an electronic component is mounted is installed in a casing.

Chip components such as capacitors have many restrictions on the mounting structure in that the linear expansion coefficient is significantly different from that of copper.
For example, when the thick film electrode at the end of the chip capacitor is mounted on the electrode pad of the circuit board by solder bonding, a thermal stress is generated at the bonded portion as the temperature changes during use. . When the generated stress is concentrated on the chip capacitor body, there is a concern that the worst chip capacitor is destroyed.

As a means to prevent the destruction of the chip capacitor due to such thermal stress, the area where the solder gets wet is limited by the shape of the electrode so that the restriction due to soldering is not in the chip capacitor body but in the electrode. Etc. have been devised.
However, even with this method, in a large-capacity chip capacitor with a large size, the thermal stress accompanying the temperature change during use increases, and when soldering directly to a thick film electrode, the generated thermal stress exceeds the proof stress of the chip capacitor. There was a problem with it.

  As a mounting structure for a chip component that solves the above problems, a composite multilayer ceramic capacitor in which a metal terminal having a low linear expansion coefficient is bonded to an electrode is soldered to a wiring board via the metal terminal. . In this structure, the height of the metal terminal is larger than the thickness of the capacitor, and the capacitor is mounted on the wiring board with a gap that prevents the influence of thermal stress (for example, see Patent Document 1). .

  The chip component mounting structure described in Patent Document 1 is solder-bonded to a wiring board via a metal terminal of the chip component, and heat from the chip component is transmitted to the substrate via the metal terminal. Since the terminal is formed of a thin plate having a spring property and has a large thermal resistance, there is a problem that heat conductivity is low and heat dissipation of the chip component is insufficient.

Electronic devices using a wiring board on which chip components are mounted are also used for in-vehicle electrical components such as an electric power steering, an electric compressor, an electric air conditioner, an electric pump, a DC-DC converter, and an inverter.
The chip component mounting structure described in Patent Document 1 has a problem that the heat dissipation property of the chip component is further insufficient because the use temperature becomes high in such applications.
In addition, since large vibrations are applied to in-vehicle electrical components, the mounting structure that is soldered to the circuit board via thin metal terminals has a problem that the vibration is transmitted to the chip components and the chip components are damaged. It was.

Therefore, a mounting structure that dissipates the heat of the electronic component by a heat transfer path other than the heat transfer to the wiring board via the electrode is desired.
The electronic component mounting structure does not rely on heat transfer to the wiring board side for heat dissipation of electronic components. Components such as capacitors and coils are not mounted on the wiring board surface. There are some which are mounted on the case frame and provided with a heat transfer material between the surface opposite to the case frame in these components and the inner surface of the case lid of the case body.
In this mounting structure, heat generated from a capacitor, a coil, or the like, which is a mounting component, is transmitted to the case lid through a heat transfer material and radiated from the outer surface of the case lid (for example, Patent Document 2). reference).

Japanese Patent Laid-Open No. 11-045821 (page 3, FIG. 10) Japanese Patent Laying-Open No. 2010-167871 (page 7-8, FIG. 4)

  In the mounting structure described in Patent Document 2, components such as a capacitor and a coil are mounted on the case frame, and the case lid is also mounted on the case frame, and the heat generated by the components such as the capacitor and the coil is The heat is transferred to the case lid via a heat transfer material, and the heat is released almost from the surface of the case lid. Therefore, when the amount of heat generated from components such as capacitors and coils is large, there is a problem that the heat dissipation becomes insufficient. there were.

  In addition, by installing the half-shell-shaped case lid on the case frame, the heat transfer material is pressed against the surface of the component such as a capacitor or coil on the inner surface of the case lid, so the heat transfer material is used as the component. If the pressing pressure cannot be adjusted and the pressing pressure is weak, the heat transfer material may be displaced or removed when vibration is applied.On the other hand, if the pressing pressure is strong, excessive force is applied to the part and the part is damaged. There was a problem.

  The present invention has been made in order to solve the above-described problems, and has improved the heat stress resistance, vibration resistance, and heat dissipation of the chip component mounted on the wiring board, and has improved reliability. It is an object to provide an electronic component mounting structure that is excellent and can be used in a high-temperature environment.

  An electronic component mounting structure according to the present invention includes a wiring board, an electronic component mounted on the circuit pattern of the wiring board, electrodes provided at both ends of the electronic component, and the side opposite to the circuit pattern side of the electronic component. An electronic component comprising: a heat transfer material disposed on the surface; and a cover that is in contact with the surface of the heat transfer material opposite to the contact surface with the electronic component and is fixed in parallel to the circuit pattern. A mounting structure in which an electronic component is a chip component, and an electrode has a circuit bonding portion for bonding to a circuit pattern, and a standing leg portion that floats the electronic component from the circuit pattern and has a spring property. The total height of the electronic component, which is the height from the pattern surface to the heat transfer material side surface of the electronic component, and the thickness of the heat transfer material is thinner after fixing than before fixing the cover. The spring constant of the heat transfer material is the spring constant of the electrode. The cover is fixed to the wiring board via spacers with metal bolts and nuts, and the distance from the circuit pattern forming surface of the wiring board to the inner surface of the cover is an electronic component. The height of the spacer is set so as to be smaller than the total of the installation height of the electronic component before fixing the cover and the thickness of the heat transfer material.

  An electronic component mounting structure according to the present invention includes a wiring board, an electronic component mounted on the circuit pattern of the wiring board, electrodes provided at both ends of the electronic component, and the side opposite to the circuit pattern side of the electronic component. An electronic component comprising: a heat transfer material disposed on the surface; and a cover that is in contact with the surface of the heat transfer material opposite to the contact surface with the electronic component and is fixed in parallel to the circuit pattern. A mounting structure in which an electronic component is a chip component, and an electrode has a circuit bonding portion for bonding to a circuit pattern, and a standing leg portion that floats the electronic component from the circuit pattern and has a spring property. The total height of the electronic component, which is the height from the pattern surface to the heat transfer material side surface of the electronic component, and the thickness of the heat transfer material is thinner after fixing than before fixing the cover. The spring constant of the heat transfer material is the spring constant of the electrode. The cover is fixed to the wiring board via spacers with metal bolts and nuts, and the distance from the circuit pattern forming surface of the wiring board to the inner surface of the cover is an electronic component. The height of the spacer is set to be smaller than the total of the installation height of the electronic component and the thickness of the heat transfer material before fixing the cover, and is mounted on the wiring board. The chip component is excellent in heat stress resistance, vibration resistance and heat dissipation.

It is a cross-sectional schematic diagram of the mounting structure of the electronic component concerning Embodiment 1 of this invention. It is a cross-sectional schematic diagram which shows the state which provided the heat sink in the wiring board in the mounting structure of the electronic component concerning Embodiment 1 of this invention. It is a cross-sectional schematic diagram of the mounting structure of the electronic component concerning a reference form. It is a cross-sectional schematic diagram of the mounting structure of the electronic component concerning a reference form . It is a cross-sectional schematic diagram of the mounting structure of the electronic component concerning a reference form. It is a figure explaining the cover body in which the protrusion part of another shape was provided in the mounting structure of the electronic component concerning a reference form. It is the upper surface schematic diagram (a) and side surface schematic diagram (b) explaining the cover body in the mounting structure of the electronic component concerning a reference form. It is a side surface schematic diagram explaining the cover of another example in the mounting structure of the electronic component concerning a reference form. It is the inner surface schematic diagram (a) and side surface schematic diagram (b) explaining the cover in the mounting structure of the electronic component concerning Embodiment 2 of this invention. It is a side surface schematic diagram explaining the cover of another example in the mounting structure of the electronic component concerning Embodiment 2 of this invention. It is a cross-sectional schematic diagram which shows the state of the heat-transfer material contact surface of the cover used by the mounting structure of the electronic component concerning Embodiment 3 of this invention. It is a plane schematic diagram which shows the 1st shape projection part (a) and the 2nd shape projection part (b) which were formed in the heat-transfer material contact surface of the cover in Embodiment 3 of this invention. . It is a front schematic diagram which shows the electrode (a) of a 1st shape, and the electrode (b) of a 2nd shape of the electronic component in the mounting structure of the electronic component concerning Embodiment 4 of this invention. It is a side surface schematic diagram which shows the electrode (a) of a 1st shape, and the electrode (b) of a 2nd shape of the electronic component in the mounting structure of the electronic component concerning Embodiment 5 of this invention.

Embodiment 1 FIG.
FIG. 1 is a schematic cross-sectional view of a mounting structure for an electronic component according to Embodiment 1 of the present invention.
As shown in FIG. 1, the electronic component mounting structure 100 according to the present embodiment is provided on the wiring substrate 30, the electronic component 10 mounted on the circuit pattern of the wiring substrate 30, and both ends of the electronic component 10. The electrode 20, the heat transfer material 40 disposed on the surface opposite to the circuit pattern side of the electronic component 10, and the contact surface (referred to as an electronic component contact surface) of the heat transfer material 40 with the electronic component 10. A cover 50 disposed on the surface (referred to as a cover contact surface), a spacer 75 provided between the cover 50 and the wiring substrate 30, and the cover 50 via the spacer 75. The cover 50 is fixed to the wiring substrate 30 in parallel with the circuit pattern surface.

In the present embodiment, the wiring substrate 30 is an aluminum substrate on which a copper foil circuit pattern is formed via an insulating layer.
The electronic component 10 is a chip component for surface mounting of a resistor or a capacitor, and electrodes 20 are connected to both ends thereof, and one end of the electrode 20 is bent inward, and the bent portion is a wiring. A circuit joint portion 24a is joined to the circuit pattern of the substrate 30 with solder.

Further, the electrode 20 is provided with a standing leg portion 24b, and a gap is formed between the circuit joint portion 24a and the surface of the electronic component 10 on the circuit pattern side. That is, the electronic component 10 is mounted in a state of being lifted from the wiring board 30.
Further, for example, a 42 alloy is used for the electrode 20, the width thereof is the same as the width of the electronic component 10, and the thickness is made as thin as 0.1 to 0.2 mm in order to provide springiness, and the electronic component 10 is wired. The height of the leg portion 24b that floats from the substrate 30 is about 0.3 mm to 1 mm.

In the electronic component mounting structure 100 according to the present embodiment, the electronic component 10 is bonded to the circuit pattern of the wiring board via the electrode 20 provided with the standing leg portion 24b. Even if a large chip component such as 3216, 4532, or 5750 is used, the thermal stress generated in the chip component can be reduced.
Further, when the electronic component 10 is a capacitor mainly composed of ceramic, using a 42 alloy having a low linear expansion coefficient of about 5 ppm / ° C. as the material for forming the electrode 20 is particularly effective for reducing thermal stress. It is. In addition to the 42 alloy, a so-called Invar alloy is used as the material for forming the electrode 20, and the thermal stress can be similarly reduced.

In the electronic component mounting structure 100 of the present embodiment, the heat of the electronic component 10 is conducted to the wiring board 30 through the electrode 20 and is radiated from the wiring board 30, and the heat transfer material of the electronic component 10 is also used. Since the contact surface with 40 (referred to as a heat transfer material contact surface) is in contact with the inner surface of the cover 50 via the heat transfer material 40, it is also conducted to the cover 50 and radiated from the outer surface of the cover 50. Is done. The cover 50 is preferably a metal from the viewpoint of heat dissipation.
In addition, the heat conducted to the cover 50 can be efficiently conducted to the wiring board 30 and is radiated from the wiring board 30 by forming the bolts 70 of metal.

In the present embodiment, since the electrode 20 is formed of a thin plate and the heat transfer area of the electrode 20 is small, the amount of heat conducted to the wiring board 30 via the electrode 20 is small. In particular, when 42 alloy is used for the electrode 20, the heat conductivity of the 42 alloy is small, so that the amount of heat conducted to the wiring board 30 is further reduced.
However, the electronic component mounting structure 100 according to the present embodiment has a path for conducting heat of the electronic component and dissipating it to the outside in addition to the electrodes, and has excellent heat dissipation.

  In the electronic component mounting structure 100 according to the present embodiment, the distance between the circuit pattern surface of the wiring board 30 and the inner surface of the cover 50 is adjusted by the spacer 75, so that the space between the electronic component 10 and the cover 50 is adjusted. By adjusting the pressure applied to the heat transfer material 40 installed in the heat transfer material 40, reliable contact between the electronic component contact surface of the heat transfer material 40 and the heat transfer material contact surface of the electronic component 10, and the cover of the heat transfer material 40 Heat radiation is improved by realizing reliable contact between the contact surface and the inner surface of the cover 50 and by reducing thermal resistance in heat conduction from the electronic component 10 to the cover 50.

Moreover, since the pressing force applied to the electronic component 10 from the cover 50 through the heat transfer material 40 can be adjusted, the destruction of the electronic component due to the pressing force can also be prevented.
In addition, the electrode 20 is provided with a standing leg portion 24b, and the standing leg portion 24b has a spring property. For example, even if the pressing force from the cover 50 to the electronic component 10 becomes excessive, the standing leg portion 24b. Since the pressing force is reduced, the electronic component 10 can be prevented from being broken.

  In addition, the electronic component 10 is pressed by the cover 50 through the heat transfer material 40 and is fixed by the cover 50 through the heat transfer material 40, so even if vibration is applied. The electronic component 10 can be prevented from vibrating greatly and has excellent vibration resistance. In addition, by adjusting the spacer 75, it is possible to reliably apply a pressing force, and it is possible to prevent the heat transfer material 40 from being displaced or detached.

The thickness of the heat transfer material 40 is preferably as thin as possible because it reduces the thermal resistance.
Therefore, in the electronic component mounting structure according to the present embodiment, the height from the circuit pattern surface of the wiring board 30 to the heat transfer material contact surface of the electronic component 10 (referred to as the installation height of the electronic component) and the heat transfer material 40. The height of the spacer 75 is adjusted such that the total thickness of the spacer 75 is thinner after the cover 50 is fixed to the wiring board 30 than before the cover 50 is fixed to the wiring board 30.
That is, the distance from the circuit pattern forming surface of the wiring board 30 to the inner surface that is the heat transfer material contact surface of the cover 50 fixed to the wiring board 30 is larger than the installation height of the electronic component 10, and the cover 50 is fixed. The height of the spacer 75 is set so as to be smaller than the total of the installation height of the previous electronic component 10 and the thickness of the heat transfer material 40.

Since it has such a structure, when the cover 50 is fixed, pressure is applied so that the cover 50 presses the heat transfer material 40 against the electronic component 10, and the heat transfer material 40 flows like grease or an adhesive. In the case of a material having a characteristic, the heat transfer material 40 can be removed, and in the case of a sheet, the heat transfer material 40 can be rolled and thinned to reduce the heat resistance of the heat transfer material 40. In addition, contact thermal resistance between the electronic component 10 and the heat transfer material 40 and between the heat transfer material 40 and the cover 50 can be reduced, and heat dissipation can be further improved.
In addition, height differences caused by variations in mounting of individual electronic components can be absorbed, and heat dissipation can be improved at all contact points.

If a flexible material is used for the heat transfer material 40 and the spring constant thereof is set smaller than the spring constant of the electrode 20 having the spring property, the thickness of the heat transfer material 40 is reduced by the pressing force. Can be easily achieved.
Examples of such a material for the heat transfer material 40 include a silicone sheet, and those having a thermal conductivity of about 6 W / mK are preferable.

Further, when the spring constant of the heat transfer material 40 is made smaller than that of the electrode 20, for example, the thickness of the heat transfer material 40 is absorbed so as to absorb variations in the thickness of the heat transfer material sheet and variations in the installation height of the electronic component after mounting. Even when the heat transfer material 40 is increased, it is possible to prevent the heat transfer material 40 from being greatly deformed and the deformation amount of the electrode 20 from increasing, and to prevent the electrode 20 from being damaged.
In the case where the cover 50 is directly pressed against the electronic component 10 when the electronic component 10 is mounted at an inclination, the cover 50 hits the electronic component 10 as in the present embodiment. By interposing the heat transfer material 40, no piece contact occurs, the increase of stress due to the piece contact can be prevented, and the electronic component 10 can be prevented from being damaged.

FIG. 2 is a schematic cross-sectional view showing a state in which a radiator is provided on the wiring board in the electronic component mounting structure according to Embodiment 1 of the present invention.
In the electronic component mounting structure 100 of the present embodiment shown in FIG. 2, an electronic component mounting structure 100a in which a heat sink 90 such as a heat sink is provided on the surface opposite to the electronic component mounting surface of the wiring board 30 is shown. The thermal resistance on the wiring board 30 side can be reduced and the heat dissipation can be improved.
It is preferable to provide a heat transfer material between the wiring board 30 and the radiator 90, and vibration resistance can be improved by mechanically connecting the wiring board 30 and the radiator 90 by screwing or the like. it can.

In the electronic component mounting structures 100 and 100a according to the present embodiment, the sum of the height of the electronic component and the thickness of the heat transfer material 40 is greater than before the cover 50 is fixed to the wiring board 30. It is set to be thinner, and the pressing force is always applied to the electronic component and heat transfer material, and even if vibration is applied, the vibration energy is attenuated, and the amplitude of the electronic component increases due to unnecessary resonance. Can be prevented.
In addition, since the heat transfer material 40 is interposed between the electronic component 10 and the cover 50, problems such as the cover 50 hitting the electronic component 10 and rubbing against it can be prevented.

In this embodiment, the wiring substrate 30 and the cover 50 are fixed by screws, but if a spacer is provided, the cover 50 can be fixed by a method that can apply pressure to the wiring substrate 30. For example, press-fitting, patching, and fixing with a leaf spring may be mentioned, and a pressing mechanism may be provided.
In addition, when fixing the wiring board 30 to the cover 50 is a screw, the spacer 75 may be omitted if the thickness of the heat transfer material 40 can be controlled by the tightening torque of the screw 70.

FIG. 3 is a schematic cross-sectional view of an electronic component mounting structure according to a reference embodiment.
As shown in FIG. 3, the electronic component mounting structure 200 includes a wiring substrate 30, a first electronic component 10 a, a second electronic component 11, and a third electronic component mounted on the circuit pattern of the wiring substrate 30. The component 12, the electrodes 20 a provided at both ends of the first electronic component 10 a, the case main body 60 to which the wiring board 30 on which each electronic component is mounted is fixed, and the cover 50 a serving as a lid of the case main body 60 And a heat transfer material 40 disposed between the cover 50a and the first electronic component 10a.
That is, the wiring board 30 on which electronic components are mounted is housed in a housing formed by the housing body 60 and the cover 50a.

The housing main body 60 includes a portion (referred to as a substrate mounting portion) 60b on which the wiring board 30 is mounted and a peripheral wall portion 60a that is a wall provided around the substrate mounting portion 60b. It is in contact with the upper surface of the part 60 a and is arranged in parallel to the circuit pattern of the wiring board 30.
The heat transfer material 40 is disposed between and in contact with the inner surface of the cover 50a and the heat transfer material contact surface of the first electronic component 10a.

In FIG. 3, a wiring substrate 30 is an aluminum substrate having a circuit pattern formed of copper foil on the surface via an insulating layer.
The housing body 60 is provided with fins 61 and is also a heat radiator that dissipates heat from the wiring board 30 on which electronic components are mounted, and is preferably formed of metal.
The cover 50a is also preferably a metal from the viewpoint of heat dissipation.
The heat transfer material 40 is the same as that of the first embodiment.

The second electronic component 11 is a component in which a semiconductor element is packaged. An electrode is formed on the entire solder joint surface, and the heat resistance is high.
The third electronic component 12 is a small chip component whose package size abbreviations are 1005, 1608, 2012, has high heat stress resistance, and has an electrode 21 provided from the side surface to the back surface and the front surface of the chip component body. Even if soldered to the wiring board 30, it can be used without any problem.
The first electronic component 10a is a chip component such as a large resistor or capacitor whose package size abbreviations are 3216, 4532, 5750, etc., similar to the electronic component 10 in the first embodiment.
The structure of the electrode 20a of the first electronic component 10a is the same as the structure of the electrode 20 of the electronic component 10 in the first embodiment.

In FIG. 3, the wiring board 30 is mechanically fixed to the housing main body 60 with screws 73 or the like, but in order to reduce the contact thermal resistance between the wiring board 30 and the housing main body 60, A heat transfer material may be provided between the body body 60 and fixed.
The cover 50a is mechanically fixed to the upper surface of the peripheral wall 60a of the housing main body 60 by a fixing mechanism such as a screw 72, and the cover 50a serving as a lid and the housing main body 60 serving as a case main body. The case is formed.
Further, since the cover 50 a is parallel to the circuit pattern forming surface of the wiring board 30, the peripheral wall 60 a of the housing body 60 causes the inner surface of the cover 50 a and the circuit pattern forming surface of the wiring board 30 to be formed. The interval is specified.

Also in the electronic component mounting structure 200 shown in FIG. 3, the total of the installation height of the first electronic component 10a and the thickness of the heat transfer material 40 is greater than before the cover 50a is fixed to the peripheral wall portion 60a. The height of the peripheral wall portion 60a is adjusted so that the thickness after fixing becomes thinner.
That is, the distance from the circuit pattern forming surface of the wiring board 30 to the inner surface that is the heat transfer material contact surface of the cover 50a fixed to the peripheral wall portion 60a (referred to as the distance from the wiring board to the cover) is the first. The height of the peripheral wall 60a is smaller than the total installation height of the electronic component 10a and smaller than the total of the installation height of the first electronic component 10a and the thickness of the heat transfer material 40 before fixing the cover 50a. Is set.
Also in FIG. 3, the heat transfer material 40 is made of fluid grease or adhesive, or a sheet that is pressed and thinned.

The first electronic component 10a, which is a chip component having a large size and a large calorific value, has the same electrode structure as the electrode structure of the electronic component 10 in the first embodiment, and can reduce thermal stress applied to the component. ing.
Therefore, the thermal resistance from the first electronic component 10a to the wiring board, that is, from the first electronic component 10a to the housing body 60, which is a heat radiating body, is large, and heat dissipation through this heat conduction path is insufficient.

  However, in the electronic component mounting structure 200 shown in FIG. 3, since the distance from the wiring board 30 to the cover 50a is as described above, the heat from the first electronic component 10a is transferred. It is conducted to the cover 50a through the heat material 40, and can be radiated from the outer surface of the cover 50a. In addition, the heat conducted to the cover 50 a is also conducted to the housing body 60 and is radiated from the housing body 60.

In addition, since the distance from the wiring board 30 to the cover 50a is as described above, the first electronic component 10a is pressed by the cover 50a via the heat transfer material 40, and the heat transfer Although it is via the material 40, it is fixed by the cover 50a and has excellent vibration resistance. And by adjusting the height of the surrounding wall part 60a, a pressing force can be applied reliably and it can also prevent that the heat-transfer material 40 slip | deviates or remove | deviates.
Further, since the electrode structure of the first electronic component 10a is the same as the electrode structure of the electronic component 10 of the first embodiment, the pressing force applied to the first electronic component 10a from the cover 50a is applied to the spring-like stance stand. It can be relaxed at the portion, and the destruction of the first electronic component 10a can be prevented.
Further, it is possible to prevent the cover 50a from hitting the first electronic component 10a.

In FIG. 3, an aluminum substrate is used for the wiring board 30 because of its high heat dissipation, but a printed board or a ceramic board using a resin may be used.
In the case of a printed circuit board, in order to improve the heat dissipation from the housing body 60, it is preferable to reduce the thermal resistance by providing a through hole, a copper pillar, or the like directly under the heat generating component. However, when there is an electrode on the back surface of the wiring board 30 and the potential of the electrode and the casing body 60 are different, an insulating layer is provided between the wiring board 30 and the casing body 60.

Further, in the case of a printed circuit board using a resin or a ceramic substrate formed of a ceramic material with low thermal conductivity, the thermal resistance from the first electronic component 10a to the housing body 60, which is also a radiator, further increases. Therefore, this configuration in which the heat of the first electronic component is radiated from the cover 50a is particularly effective.
In FIG. 3, electronic components are mounted on the wiring board 30, but a circuit pattern made of copper foil may be formed on the surface of the housing body 60 via an insulating layer, and the electronic components may be mounted on this circuit pattern. . In this case, in particular, the heat dissipation of the second electronic component 11 and the third electronic component 12 is improved.

In FIG. 3, the first electronic component 10a is provided with a heat transfer material, but the second electronic component 11 and the third electronic component 12 are provided with a heat transfer material to cover the heat of these electronic components. It may be conducted to the body and radiated from the cover.
In FIG. 3, the wiring substrate 30 is fixed to the housing body 60 and the cover 50a is fixed to the housing body 60 by screws, but the wiring substrate 30 is fixed to apply pressure to the housing body 60. And a fixing method in which the cover 50a is pressed against the housing body 60. Examples of such fixing methods include press-fitting, patching, and fixing by a leaf spring, and a presser mechanism is provided. May be.

FIG. 4 is a schematic cross-sectional view of an electronic component mounting structure according to a reference embodiment .
As shown in FIG. 4, the electronic component mounting structure 300 uses a cover 50 b in which fins 51 are provided on the outer surface on the opposite side of the contact portion with the heat transfer material 40, as the cover. The electronic component mounting structure shown in FIG. 3 is similar to the electronic component mounting structure shown in FIG. 3 and has the same effect as the electronic component mounting structure shown in FIG.
Moreover, since the fin 51 is provided on the opposite side of the contact part with the heat transfer material 40 of the cover, the heat dissipation is improved.
And since the fin 51 also serves as reinforcement of the cover, the thickness of the cover can be reduced.

The fin 51 may be mechanically connected to the cover by screwing or the like via a heat transfer material. However, it is efficient to form the cover and the fin integrally, and the thermal resistance is lowered. preferable.
In FIG. 4, the fins 51 are provided only around the electronic component that generates heat from the cover, but may be provided on the outer surface of the entire cover.
Providing the fin on the opposite side of the contact portion of the cover with the heat transfer material can also be applied to the electronic component mounting structure of Embodiment 1 and has the same effect.

FIG. 5 is a schematic cross-sectional view of an electronic component mounting structure according to a reference embodiment.
As shown in FIG. 5, the electronic component mounting structure 400 includes a cover 50 c in which a first protrusion 53 is provided in a portion where the first electronic component 10 a on the inner surface is projected on the cover. The distance from the circuit pattern forming surface of the wiring board 30 to the surface of the first protrusion 53, which is the heat transfer material contact surface of the cover 50c fixed to the peripheral wall 60a, is that of the first electronic component 10a. Other than the height of the peripheral wall portion 60a being set so as to be smaller than the total of the installation height of the first electronic component 10a and the thickness of the heat transfer material 40 before the cover 50c is fixed. 3 is the same as the electronic component mounting structure shown in FIG. 3, and has the same effect as the electronic component mounting structure shown in FIG.

  In the electronic component mounting structure 400, the cover 50c is provided with the first projecting portion 53 on the projected portion of the first electronic component 10a on the inner surface. Even when the electronic component 13 that is considerably higher than the installation height of the first electronic component 10a is mounted, the thickness of the heat transfer material 40 disposed between the first electronic component 10a and the cover 50c is reduced. It is possible to prevent an increase in the thermal resistance of the conduction path that conducts the heat of the first electronic component 10a to the cover.

In FIG. 5, the size of the contact surface of the first projecting portion 53 with the heat transfer material 40 is larger than the size of the heat transfer material contact surface of the first electronic component 10a. The heat can be spread toward the periphery of the protruding portion 53, and the heat dissipation can be enhanced.
Although not shown, as shown in FIG. 4 , fins may be provided on the outer surface of the cover opposite to the contact portion with the heat transfer material.

FIG. 6 is a diagram for explaining a cover provided with a first protrusion having a different shape in an electronic component mounting structure according to another reference embodiment.
As shown in FIG. 6, the cover 50d provided with the first protrusion of another shape includes a first protrusion 54 formed by plastic deformation of the cover without greatly changing the thickness. It is a thing. The first protrusion 54 can be formed by press working, and the cover can be easily manufactured.

  Although not shown, the first protrusion may be provided on a portion of the cover where the first electronic component is projected, as well as on a portion where another electronic component is projected. It is also possible to dissipate heat from the cover by disposing a heat transfer material between the cover and the other electronic component.

FIG. 7 is a schematic top view (a) and a schematic side view (b) for explaining a cover in a mounting structure for an electronic component according to another reference embodiment.
The electronic component mounting structure shown in FIG. 7 is a cover in which a through hole 80 is provided around the first protrusion 53 around the three sides of the first protrusion 53 of the cover 50c. The electronic component mounting structure shown in FIG. 5 is the same as that shown in FIG. 5 except that the body 50e is used.

FIG. 8 is a schematic side view illustrating another example of the cover in the electronic component mounting structure according to another reference embodiment.
The electronic component mounting structure shown in FIG. 8 has a cover in which a through-hole 80 is provided around the first protrusion 54 around the first protrusion 54 of the cover 50d. Except for using the body 50f, the electronic component mounting structure 400 is the same as that shown in FIG.

In the form shown in FIG. 8, since the through-hole is provided around the first protrusion of the cover so as to surround the first protrusion, the first protrusion is interposed via the heat transfer material of the cover. The portion to which the pressing force is applied to the electronic component has a spring property, and the stress applied to the first electronic component can be relaxed.
In addition, heat dissipation can be improved by promoting convection around the first electronic component.

Embodiment 2. FIG.
FIGS. 9A and 9B are an inner surface schematic diagram (a) and a side surface schematic diagram (b) for explaining a cover in the electronic component mounting structure according to the second embodiment of the present invention .
The electronic component mounting structure according to the present embodiment shown in FIG. 9 has a second protrusion 55 formed on the inner surface of the cover 50a so as to surround the outer periphery of the first electronic component 10a. 3 is the same as the electronic component mounting structure shown in FIG. 3 except that the provided cover 50g is used.

In the electronic component mounting structure using the cover 50g, the positioning of the heat transfer material 40 is facilitated and the productivity is improved, and the displacement of the heat transfer material 40 can be prevented and the long-term reliability is improved.
As shown in FIG. 9B, when the second protrusion 55 has a fin structure, heat dissipation is improved.
This cover structure can also be applied to the electronic component mounting structure shown in the first embodiment or FIG .

FIG. 10 is a schematic side view illustrating another example of the cover in the electronic component mounting structure according to Embodiment 2 of the present invention .
In the electronic component mounting structure according to the present embodiment shown in FIG. 10, a groove 56 in the thickness direction is formed on the outer surface of the cover 50a in the cover, and a protrusion is formed on the inner surface side of the cover 50a. 3 is the same as the electronic component mounting structure shown in FIG. 3 except that a cover 50h provided so as to surround the outer periphery of one electronic component 10a is used.

In the electronic component mounting structure using the cover 50h, positioning of the heat transfer material 40 is facilitated and productivity is improved, and the first electronic component in the cover is pressed against the first electronic component via the heat transfer material. The portion to which is added has springiness, and the stress applied to the first electronic component can be relaxed.
This cover structure can also be applied to the electronic component mounting structure of the first embodiment.

Embodiment 3 FIG.
FIG. 11: is a cross-sectional schematic diagram which shows the state of the heat-transfer material contact surface of the cover used with the mounting structure of the electronic component concerning Embodiment 3 of this invention.
FIG. 12 is a plan view showing a first shape protrusion (a) and a second shape protrusion (b) formed on the heat transfer material contact surface of the cover according to Embodiment 3 of the present invention. It is a schematic diagram.

As shown in FIG. 11, the electronic component mounting structure according to the present embodiment is the same as the embodiment except that the cover is a cover 50 i provided with a plurality of fine protrusions 52 on the heat transfer material contact surface. This is the same as the electronic component mounting structure 1.
And as for the shape of the projection part 52 of a heat-transfer material contact surface, the groove-like projection part 521 shown to Fig.12 (a) and the bump-like projection part 522 shown to FIG.12 (b) are mentioned, for example.

In the cover 50i in which the protrusion 52 is formed on the heat transfer material contact surface as in the present embodiment, when the heat transfer material 40 is pressed by the cover 50i, the heat transfer material flows such as grease or adhesive. In the case of a heat-resistant material, the heat transfer material has a higher drainage effect, and a cover with high heat conductivity is mixed in the heat transfer material region, so that the heat resistance can be reduced and the heat dissipation can be improved. .
In addition, when the heat transfer material is a sheet, in addition to extending the heat transfer material thinly, the heat transfer material region also contains a cover with high thermal conductivity, which can reduce the thermal resistance and release heat. Can increase the sex.

The protrusion 52 of the cover 50i may have a flat tip, but as shown in FIG. 11, it is preferable to make the tip narrower because the effect is great.
When the protrusion 52 is a groove-like protrusion 521, the direction of the groove is preferably the short direction of the electronic component 10.
And the projection part 52 can be formed simultaneously with the manufacture of the cover 50i.
The cover provided with a plurality of fine protrusions of the present embodiment can be applied as the cover of the second embodiment and has the same effect.

Embodiment 4 FIG.
FIG. 13: is a front schematic diagram which shows the electrode (a) of a 1st shape, and the electrode (b) of a 2nd shape of the electronic component in the mounting structure of the electronic component concerning Embodiment 4 of this invention. is there.
As shown in FIG. 13, the electronic component mounting structure according to the present embodiment is the same as the electronic component mounting structure according to the first embodiment, except that standing legs of the electrodes of the electronic component 10 are bent. .

  That is, in the present embodiment, as shown in FIG. 13A, the first shape electrode is an electrode 20b in which the standing leg portion 24b is bent inward at a certain angle, and the second shape electrode is As shown in FIG. 13B, the standing leg portion 24b is an electrode 20c bent inwardly in a dogleg shape.

The electronic component mounting structure according to the present embodiment has the same effects as the electronic component mounting structure according to the first embodiment, and the electrodes of the electronic component have the above-described shape. The spring property is high, the ability to relieve the pressing force is large, and the effect of preventing the electronic component 10 from being broken is great.
The electrode of the electronic component of the present embodiment can be applied to the electrode of the electronic component or the first electronic component of the second and third embodiments, and has the same effect.

Embodiment 5 FIG.
FIG. 14 is a schematic side view showing the first shape electrode (a) and the second shape electrode (b) of the electronic component in the electronic component mounting structure according to Embodiment 5 of the present invention. is there.
The electronic component mounting structure according to the present embodiment is divided in the longitudinal direction as shown in FIG. 14A as an electrode having a first shape on the electrodes joined to the respective end portions of the electronic component 10. The electrode 20d or the electrode 20e shown in FIG. 14B as the second shape electrode is used except that the electrode 20e in which the junction between the circuit junction and the electronic component is divided in the longitudinal direction is used. This is the same as the electronic component mounting structure according to the first aspect.

The electronic component mounting structure of the present embodiment has the same effect as the electronic component mounting structure of the first embodiment, and the electronic component 10 is shown in FIG. 14 (a) or FIG. 14 (b). As described above, even when at least the joint portion of the electrode with the electronic component and the circuit joint portion are divided in the longitudinal direction of the electrode, and the area where the electrode is solder-bonded to the wiring board 30 increases, the thermal stress increases. Thermal stress can be relaxed.
In the present embodiment, the whole electrode or the local division is divided into two, but it is not limited to this as long as processing is possible.
The electrode of the electronic component of the present embodiment can be applied as the electrode of the electronic component or the first electronic component of Embodiments 2 to 4 , and has the same effect.

  The electronic component mounting structure according to the present invention reduces thermal stress applied to the chip component mounted on the wiring board and efficiently radiates heat from the chip component, and is used in a high temperature environment. Used for equipment.

10 electronic component, 10a first electronic component, 11 second electronic component,
12 Third electronic component, 13 Electronic component,
20, 20a, 20b, 20c, 20d, 20e, 21 electrodes,
24a circuit junction part, 24b stand part, 30 wiring board, 40 heat transfer material,
50, 50a, 50b, 50c, 50d, 50e, 50f, 50g
50h, 50i Cover, 51 fin, 52 projection, 521 groove projection,
522 Bump-like protrusion, 53, 54 First protrusion, 55 Second protrusion, 56 groove, 60 Housing body, 60a Perimeter wall, 60b Substrate mounting part, 61 Fin, 70 Bolt, 71 Nut, 72, 73 screws, 75 spacers, 80 through holes, 90 heat sinks,
100, 100a, 200, 300, 400 Electronic component mounting structure.

Claims (9)

A wiring board; an electronic component mounted on the circuit pattern of the wiring board; electrodes provided on both ends of the electronic component; and heat transfer disposed on a surface of the electronic component opposite to the circuit pattern side. A mounting structure for an electronic component comprising: a cover that is in contact with a surface of the heat transfer material opposite to the contact surface with the electronic component and is fixed in parallel to the circuit pattern. And
The electronic component is a chip component, and the electrode has a circuit joint portion that joins the circuit pattern, and a standing leg portion that floats the electronic component from the circuit pattern and has a spring property. The total height of the electronic component, which is the height from the surface to the heat transfer material side surface of the electronic component, and the thickness of the heat transfer material is thinner after fixing than before fixing the cover. The spring constant of the heat transfer material is smaller than the spring constant of the electrode,
The cover is fixed to the wiring board via a spacer with metal bolts and nuts, and the distance from the circuit pattern forming surface of the wiring board to the inner surface of the cover is such that the electronic component An electronic component mounting structure in which a height of the spacer is set to be smaller than a total of an installation height of the electronic component before fixing the cover and a thickness of the heat transfer material. 2. The electronic component mounting structure according to claim 1, wherein a heat radiator is provided on a side opposite to the mounting surface of the electronic component on the wiring board. The electronic component mounting structure according to claim 1, wherein fins are provided on an outer surface side of the cover. 3. The electronic component mounting structure according to claim 1, wherein a second protrusion is provided on an outer periphery of the electronic component on the inner surface of the cover. The electronic component according to claim 1, wherein a groove in the thickness direction of the cover is formed on the outer surface of the cover, and a protrusion is provided on the inner surface side of the cover. Implementation structure. 6. The electronic component mounting structure according to claim 1, wherein a plurality of fine protrusions are provided on a contact surface of the cover with the heat transfer material. The electronic component mounting structure according to any one of claims 1 to 6, wherein a standing portion of the electrode is bent. The electron according to any one of claims 1 to 7, wherein the electrode is divided in a longitudinal direction of the electrode at least in a joint portion of the electronic component and the circuit joint portion. Component mounting structure. The electronic component mounting structure according to any one of claims 1 to 8, wherein the electrode has a thickness of 0.2 mm or less.

Images