JP2016105678A - Circuit construction body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly rigid circuit construction body.SOLUTION: A circuit construction body 1 includes: a circuit substrate 2; a plurality of bus bars 3; an electronic component 4; and an adhesive 5. The circuit substrate 2 includes an opening 21 penetrating in a thickness direction. The bus bars 3 are composed of a conductor and are overlapped with the circuit substrate 2. The electronic component 4 is soldered to the bus bars 3 through the opening 21. The adhesive 5 makes the circuit substrate 2 and the bus bars 3 to adhere to each other and fills a gap 31 between neighboring bus bars 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a circuit structure.

  A circuit structure constituting a power circuit such as an inverter or a converter is incorporated in, for example, an electrical connection box for distributing power from an in-vehicle power source to various electrical components. The circuit structure includes a plurality of bus bars, a circuit board, and electronic components, and these are electrically connected to each other to form a power circuit.

  The plurality of bus bars and the circuit board are bonded to each other with an adhesive or the like in a state of being overlapped with each other. Generally, since the linear expansion coefficient of the bus bar and the linear expansion coefficient of the circuit board are different, the bus bar and the circuit board are warped, for example, when the temperature changes. When the warp of the bus bar or the like becomes large, for example, when the electronic component is mounted on the bus bar or the circuit board by soldering, it may be difficult to arrange the electronic component at a predetermined position.

  Further, for example, when a temperature change occurs during use of the circuit structure, the circuit structure may be distorted due to a difference in linear expansion between the circuit board and the bus bar. When distortion occurs in the circuit structure, stress is generated in the solder on the circuit board, and thus there is a risk that cracks are likely to occur in the solder. Solder cracks are not preferable because they may cause defects in the circuit structure.

  Various techniques for reducing the warpage of the bus bar and the circuit board and the distortion of the circuit structure have been proposed for these problems. For example, Patent Document 1 proposes a technique for manufacturing a circuit configuration body using a bus bar configuration plate having a shape in which a plurality of bus bars are connected and integrated by a bridge portion. Patent Document 2 proposes a technique in which a bus bar and a synthetic resin reinforcing plate laminated on the bus bar are integrated by molding using a synthetic resin material.

Patent No. 4238700 Japanese Patent No. 5332562

  The technique of Patent Literature 1 can reduce the warpage of the bus bar and the circuit board while the plurality of bus bars are integrally connected by the bridge portion. However, in order for the power circuit configured on the circuit structure to function, it is necessary to finally disconnect the bridge portion. And the circuit structure after the bridge part is cut off has a problem that the rigidity is lower than that before the bridge part is cut off. For example, the warp and distortion generated during use of the circuit structure are insufficient. There is a risk of becoming.

  The technology of Patent Document 2 can improve the rigidity of the entire circuit structure by integrating the bus bar and the reinforcing plate to suppress the warpage and distortion even during use of the circuit structure. can do. However, since it is necessary to prepare the reinforcing plate separately from the bus bar, there is a problem that the number of parts increases. Moreover, since it is necessary to perform the operation | work which integrates a bus-bar and a reinforcement board, there exists a possibility that the process of producing a circuit structure may become complicated.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a circuit structure that can be manufactured by a simple process and has high rigidity.

One aspect of the present invention is a circuit board having an opening penetrating in the thickness direction;
A plurality of bus bars made of a conductor and superimposed on the circuit board;
An electronic component soldered to the bus bar through the opening;
In the circuit structure, the circuit board and the bus bar are bonded to each other, and an adhesive is filled in a gap between the adjacent bus bars.

  In the circuit structure, the circuit board and the bus bar are bonded by the adhesive, and the adhesive is filled in a gap between the adjacent bus bars. Therefore, the bus bars adjacent to each other are restrained by the adhesive, and the deformation of the bus bars can be suppressed as compared with the case where the gap is not filled with the adhesive. As a result, the rigidity of the circuit component can be improved. Since the circuit configuration body has high rigidity, for example, deformation when an external force in a bending direction is applied can be suppressed. Moreover, the said circuit structure can suppress the curvature and distortion which arise, for example, when a temperature changes.

  Moreover, the said circuit structure can perform both adhesion | attachment with the said circuit board and the said bus-bar, and filling of the said clearance gap with the said adhesive agent. Therefore, there is no need to provide a reinforcing plate or the like, and an increase in the number of parts can be suppressed. Furthermore, by performing the above two operations using the same adhesive, it is possible to easily simplify the process of manufacturing the circuit structure. As a result, the circuit structure can be easily manufactured.

As described above, the circuit structure can be manufactured by a simple process and has high rigidity.

FIG. 3 is a perspective view illustrating a main part of a circuit configuration body according to the first embodiment. FIG. 3 is an exploded perspective view illustrating a main part of the circuit configuration body according to the first embodiment. (A) A cross-sectional view showing a main part in a state in which a circuit board and a bus bar are overlaid in the step of manufacturing the circuit structure of Example 1, and (b) a main part in a state in which a liquid adhesive is applied to a gap between bus bars. Sectional drawing which shows a part, (c) Sectional drawing which shows the principal part of the state which heated and hardened the liquid adhesive agent, (d) Sectional drawing which shows the principal part in the state which mounted the electronic component. Sectional drawing which shows the principal part of the circuit structure body with a heat radiator in which the heat conductive member is interposing between the circuit structure body and the heat radiator in Example 2. FIG. Sectional drawing which shows the principal part of the circuit structure body with a heat radiator in which the adhesive agent and heat radiator in Example 3 are contacting.

  In the above circuit structure, as the adhesive, it is possible to use a liquid adhesive that has electrical insulation and exhibits a liquid state in an uncured state. The liquid adhesive can naturally enter between the circuit board and the bus bar by superposing the circuit board and the plurality of bus bars and then applying the liquid adhesive to the gap between the adjacent bus bars. Then, by heating and curing the liquid adhesive in such a state, it is possible to bond the circuit board and the bus bar and simultaneously fill the gap with the adhesive. As described above, by using the liquid adhesive, the work of bonding the circuit board and the bus bar and the work of filling the gap between the adjacent bus bars can be performed simultaneously, and the process of manufacturing the circuit structure is simplified. Can do. As the liquid adhesive, for example, a resin adhesive such as an epoxy resin adhesive and a urethane adhesive, or an inorganic adhesive such as a ceramic adhesive can be used.

  The adhesive preferably has a high elastic modulus. Since the adhesive having a high elastic modulus can more firmly restrain the adjacent bus bars, the rigidity of the circuit structure can be further increased. The adhesive preferably has excellent toughness. The adhesive having excellent toughness hardly causes peeling from the bus bar or the circuit board or destruction of the adhesive itself even if the adjacent bus bars are greatly deformed. Therefore, the state where the rigidity of the circuit structure is high can be maintained for a longer period. From the viewpoint of toughness, it is preferable to use a resin adhesive.

  When using a resin adhesive as an adhesive, it is more preferable to use an adhesive in which fillers such as glass beads and silica are blended. By blending the filler, the elastic modulus of the adhesive can be improved, and as a result, the rigidity of the circuit structure can be further improved. Further, by blending the filler, the value of the thermal expansion coefficient of the adhesive can be brought close to the bus bar and the circuit board, and the warpage that occurs during use of the circuit structure can be reduced. As a result, high temperature durability, thermal cycle durability, and the like can be improved.

  The said bus bar may be comprised from the metal which has the outstanding electrical conductivity, such as copper and a copper alloy, for example. Moreover, it can also be set as the structure which has Sn type plating film, Ni type plating film, etc. on the surface of a bus-bar.

  As for the said bus-bar, only the peripheral part of the said clearance gap may be covered with the said adhesive agent. If at least the peripheral edge of the gap is covered with the adhesive, the effect of improving the rigidity of the circuit component can be sufficiently obtained. In this case, since the bus bar is exposed on the inner side of the peripheral edge, it is possible to avoid an excessive decrease in the heat dissipation performance due to the adhesive.

  In the above case, the adhesive preferably protrudes from the opening end face of the gap. In this case, adjacent bus bars can be more firmly restrained. As a result, the rigidity of the circuit structure can be further improved.

  Moreover, the said circuit structure body may cover the substantially whole surface by the side of the said bus-bar in the lamination direction of the said circuit board and the said bus-bar with the said adhesive agent. In this case, since the bus bar is more firmly restrained by the adhesive, the rigidity of the circuit structure can be further improved.

  In the above case, the adhesive preferably has a thermal conductivity of 2.0 W / m · K or more. By using the adhesive having the thermal conductivity in the specific range, it is possible to avoid an excessive decrease in the heat dissipation performance due to the adhesive. From the same viewpoint, when an adhesive having a thermal conductivity in the specific range is used, the thickness of the adhesive existing between the circuit board and the bus bar is more preferably 0.05 to 0.3 mm. preferable.

  The circuit structure may be provided with a heat radiating body for efficiently radiating heat generated during use. Usually, the radiator is provided on the bus bar side in the stacking direction of the circuit board and the bus bar. Also, the radiator must be electrically insulated from the bus bar.

For example, a circuit component with a radiator includes the circuit component of the above aspect and a radiator that promotes heat dissipation from the circuit component,
The radiator is disposed on the bus bar side in the stacking direction of the circuit components, and is mechanically fastened to the circuit components,
A heat conductive member having insulation is sandwiched between the circuit component and the heat radiating body,
The heat conducting member may be deformed into a shape that matches both the outer surface of the circuit component and the outer surface of the radiator.

  Conventional circuit components are likely to have insufficient rigidity as described above. Therefore, when trying to mechanically fasten the circuit structure and the heat sink as described above, the circuit structure may be bent when the heat sink is fastened, or the heat sink while the circuit structure is being used. Troubles such as warping in the direction away from the head may occur. And when the bending and the curvature of a circuit structure are excessively large, a heat conductive member cannot fully be stuck to a bus bar and a heat radiator, and there exists a possibility of causing the fall of heat dissipation performance.

  Further, when the circuit structure is bent or warped, stress is generated in the solder for mounting the electronic component on the circuit board, so that the solder is likely to be cracked. Thus, it has been difficult for conventional circuit components to employ the above method from the viewpoint of avoiding deterioration in heat dissipation performance and suppressing solder cracks.

  On the other hand, since the said circuit structure has high rigidity as mentioned above, it can suppress the bending at the time of fastening, and the curvature in use. Therefore, a sufficiently large pressure can be applied to the heat conducting member by mechanical fastening, and the heat conducting member can be deformed into a shape that matches both the bus bar and the heat radiating body and can be brought into close contact with both. As a result, the circuit structure with a heat radiator can reduce the thermal resistance between the circuit structure and the heat radiator, and has excellent heat radiation performance.

  Moreover, the said circuit structure with a heat radiator can reduce the stress which generate | occur | produces in the solder on a circuit board by suppressing the bending etc. at the time of fastening. Thereby, the said circuit structure with a heat radiator can suppress generation | occurrence | production of the crack of a solder.

  Moreover, since the said circuit structure with a heat radiator can assemble | attach a heat radiator with a circuit structure by the simple method of mechanical fastening as mentioned above, it has more excellent productivity.

  In the above case, it is preferable to employ a member that has a thermal conductivity of 2.0 W / m · K or more and can be elastically deformed by fastening. Moreover, as for the said heat conductive member, it is more preferable that the thickness in the state before being pinched between a circuit board and a bus-bar is 0.05-0.5 mm. As such a heat conducting member, for example, a heat conducting sheet, a heat conducting grease, a heat conducting rubber, a heat conducting tape or the like can be employed.

  In addition, when the adhesive has a thermal conductivity of 2.0 W / m · K or more, the thermal conductive member may not be used. That is, the circuit component with a radiator includes a circuit component and a radiator, and the radiator is disposed on the bus bar side in the stacking direction of the circuit component, and the circuit component is mechanically attached to the circuit component. And may be in contact with the adhesive.

  In this case, since the heat radiating body can be electrically insulated from the bus bar by the adhesive, it is not necessary to provide the heat conducting member described above between the heat radiating body and the bus bar. Moreover, since the circuit structure with a heat radiator has a high thermal conductivity of the adhesive, it is possible to avoid a decrease in heat radiation performance. Therefore, the circuit structure with a heat radiator has excellent heat radiation performance and can reduce the number of parts.

Example 1
Embodiments of the circuit structure will be described with reference to the drawings. As shown in FIGS. 1 to 3, the circuit structure 1 includes a circuit board 2, a plurality of bus bars 3, an electronic component 4, and an adhesive 5. As shown in FIGS. 2 and 3D, the circuit board 2 has an opening 21 penetrating in the thickness direction. The bus bar 3 is composed of a conductor, and is superimposed on the circuit board 2 as shown in FIGS. The electronic component 4 is soldered to the bus bar 3 through the opening 21. As shown in FIGS. 1 and 3D, the adhesive 5 adheres the circuit board 2 and the bus bar 3 and is filled in the gap 31 between the adjacent bus bars 3.

  The bus bar 3 is made of copper or a copper alloy. The bus bar 3 of this example can be produced by appropriately performing punching or bending on a copper plate or a copper alloy plate, for example.

  The circuit board 2 has a plurality of openings 21 penetrating in the thickness direction. The opening 21 is arranged on the bus bar 3 as shown in FIG. 3, the electronic component 4 itself or the terminal of the electronic component 4 is arranged in the opening 21, and the electronic component 4 is attached to the bus bar 3 by soldering. It is configured to be implemented.

  Examples of the electronic component 4 mounted on the bus bar 3 through the opening 21 include switching elements such as a mechanical relay switch 41 and a semiconductor switching element 42. The mechanical relay switch 41 has a control terminal 411 for inputting a switching signal for controlling switching of contacts, and a main terminal 412 for flowing a current to the bus bar 3 corresponding to the switching state of the contacts. As shown in FIGS. 1 and 3D, the main body 410 of the mechanical relay switch 41 is placed on the circuit board 2. The control terminal 411 is soldered to the land 22 of the circuit board 2 as shown in FIG. The main terminal 412 is inserted into the opening 21 and soldered to the bus bar 3 as shown in FIG.

  Moreover, as the semiconductor switching element 42, MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) etc. can be used, for example. As shown in FIG. 3D, the main body 420 of the semiconductor switching element 42 is disposed in the opening 21. Although not shown in the drawing, the source terminal and the drain terminal of the semiconductor switching element 42 are soldered to the bus bar 3, and the gate terminal is soldered to the land 22 of the circuit board 2.

  In addition to the electronic components 4 soldered to the bus bar 3, electronic components are mounted on the circuit board 2 of this example (not shown). Examples of electronic components mounted on the circuit board 2 include resistors, inductors, capacitors, and diodes. On the circuit board 2, a control circuit that is a part of the power circuit is configured by these electronic components. The driving of the mechanical relay switch 41 and the semiconductor switching element 42 is controlled by a switching signal or the like output from the control circuit.

  The circuit structure 1 of this example can be manufactured by the following method, for example. First, a circuit board 2 and a bus bar intermediate 300 that is later divided into a plurality of bus bars 3 are prepared, and they are overlapped as shown in FIG. The bus bar intermediate 300 can be manufactured by stamping a copper plate or a copper alloy plate, and has a structure in which a plurality of bus bars 3 are integrally connected via a connecting portion (not shown). In FIG. 3, the gap 32 between the circuit board 2 and the bus bar intermediate body 300 is widely drawn for convenience. However, in practice, the circuit board 2 and the bus bar intermediate body 300 are in contact with each other. Very narrow.

  Next, as shown in FIG. 3B, a liquid adhesive 51 that is liquid in an uncured state is applied to the gap 31 between the adjacent bus bars 3. The liquid adhesive 51 can be applied by, for example, a drawing method using the dispenser 52. That is, the liquid adhesive 51 can be injected into the gap 31 and applied by discharging the liquid adhesive 51 from the dispenser 52 while moving the dispenser 52 along the gap 31. The liquid adhesive 51 injected into the gap 31 between the adjacent bus bars 3 naturally enters the gap 32 between the circuit board 2 and the bus bar 3.

  Instead of the method using the dispenser 52 as described above, the liquid adhesive 51 can be applied to the gap 31 by a screen printing method using a screen mask, a metal mask, or the like. In this case, the liquid adhesive 51 can be applied in the gap 31 by using a mask having an opening having a shape corresponding to the gap 31.

  Thereafter, the liquid adhesive 51 is heated and cured. Thereby, as shown in FIG. 3C, the circuit board 2 and the bus bar 3 are bonded together by the cured adhesive 5, and at the same time, the gap 31 is filled with the adhesive 5.

  Thereafter, as shown in FIG. 3D, the electronic component 4 is mounted on the bus bar 3 and the circuit board 2, and then the connecting portion of the bus bar intermediate 300 is separated to separate the plurality of bus bars 3. After the electronic component 4 is mounted, the bus bar 3 may be bent as necessary. Thus, the circuit structure 1 can be obtained.

(Example 2)
This example is an example of a circuit component 100 with a heat radiator in which a heat conducting member 7 is interposed between the circuit component 1 b and the heat radiator 6. As shown in FIG. 4, the circuit component 100 with a heat radiator of this example includes a circuit component 1 b formed by bonding a circuit board 2 and a plurality of bus bars 3, a heat radiator 6, and a heat conducting member 7. Have. Of the reference numerals used in FIG. 4, the same reference numerals as those used in the first embodiment are the same as those in the first embodiment unless otherwise specified.

  In the circuit configuration body 1 b of this example, the circuit board 2 and the plurality of bus bars 3 are bonded with the adhesive 5, and the gap 31 between the adjacent bus bars 3 is filled with the adhesive 5. Further, only the peripheral edge of the gap 31 in the bus bar 3 is covered with the adhesive 5. Further, the adhesive 5 protrudes from the opening end surface 311 of the gap 31. Such a circuit structure 1b can be manufactured by increasing the application amount of the liquid adhesive 51 in the same manner as in the first embodiment.

  The radiator 6 is disposed on the bus bar 3 side in the stacking direction of the circuit board 2 and the bus bar 3, and is mechanically fastened to the circuit structure 1b. In this example, a through hole (not shown) is provided in the circuit structure 1b, and the circuit structure 1b and the heat radiating body 6 are mechanically fastened by a screw 12 inserted through the through hole. In this example, a screw made of an insulating resin is used as the screw 12. Thereby, the bus bar 3 and the heat radiating body 6 are electrically insulated. As the screw 12, a screw made of another insulating material such as ceramics may be used. When a metal screw is used as the screw 12, the bus bar 3 and the radiator 6 are electrically connected to each other by providing the through hole in a portion of the bus bar 3 where current does not flow during use of the circuit component 1b. Can be insulated.

  The heat conducting member 7 is sandwiched between the bus bar 3 and the radiator 6. The heat conducting member 7 of this example is a heat conducting sheet that has an insulating property and is configured to be elastically deformable. The heat conducting member 7 is sandwiched between the bus bar 3 and the heat dissipating body 6 by fastening the heat conducting member 7 in a state where it is disposed between the circuit constituting body 1 b and the heat dissipating body 6. The heat conducting member 7 is deformed so as to be in close contact with both the circuit component 1 b and the heat radiating body 6 by fastening the heat radiating body 6.

  In the circuit component 100 with a heat radiator of this example, only the peripheral edge portion of the gap 31 in the bus bar 3 is covered with the adhesive 5. Therefore, the bus bar 3 exposed on the inner side of the peripheral edge portion and the heat conducting member 7 can be directly brought into contact with each other, and heat can be transmitted from the bus bar 3 to the heat conducting member 7 without using the adhesive 5. As a result, the circuit assembly 100 with a radiator has excellent heat dissipation performance.

(Example 3)
This example is an example of the circuit configuration body 101 with the radiator in which the radiator 6 and the adhesive 5c are in contact with each other. As shown in FIG. 5, the circuit component 101 with a heat radiator of this example includes a circuit component 1 c formed by adhering a circuit board 2 and a bus bar 3, and a heat radiator 6.

  In the circuit structure 1c, the circuit board 2 and the plurality of bus bars 3 are bonded with an adhesive 5c, and a gap 31 between adjacent bus bars 3 is filled with the adhesive 5c. The circuit structure 1c is covered with an adhesive 5c over substantially the entire surface on the bus bar 3 side in the stacking direction of the circuit board 2 and the bus bar 3. The adhesive 5c has a thermal conductivity of 2.0 W / m · K or more. Such a circuit structure 1c can be produced, for example, by applying a liquid adhesive on the surface of the bus bar 3 in the same manner as in the first embodiment.

  The radiator 6 is disposed on the bus bar 3 side in the stacking direction of the circuit board 2 and the bus bar 3. Further, the heat dissipating body 6 is mechanically fastened to the circuit component 1c with screws 12 and is in contact with the adhesive 5c. Others are the same as in the second embodiment. Of the reference numerals used in FIG. 5, the same reference numerals as those used in the second embodiment indicate the same components as in the second embodiment unless otherwise specified.

  Since the circuit component 101 with the radiator in this example can electrically insulate the radiator 6 from the bus bar 3 by the adhesive 5 c, it is necessary to provide the heat conducting member 7 between the radiator 6 and the bus bar 3. Disappears. Moreover, since the adhesive 5c has a high thermal conductivity, it is possible to avoid a decrease in heat dissipation performance. Therefore, the circuit configuration body 101 with the heat radiator has an excellent heat radiation performance and can reduce the number of parts.

DESCRIPTION OF SYMBOLS 1, 1b, 1c Circuit structure 2 Circuit board 21 Opening part 3 Bus bar 31 Crevice 4 Electronic component 5, 5c Adhesive

Claims (7)

A circuit board having an opening penetrating in the thickness direction;
A plurality of bus bars made of a conductor and superimposed on the circuit board;
An electronic component soldered to the bus bar through the opening;
A circuit structure having an adhesive that bonds the circuit board and the bus bar and is filled in a gap between the adjacent bus bars.   2. The circuit structure according to claim 1, wherein only the peripheral edge of the gap is covered with the adhesive.   The circuit structure according to claim 2, wherein the adhesive protrudes from the opening end face of the gap.   The circuit structure according to claim 1, wherein the circuit structure is covered with the adhesive on substantially the entire surface on the bus bar side in the stacking direction of the circuit board and the bus bar.   5. The circuit structure according to claim 4, wherein the adhesive has a thermal conductivity of 2.0 W / m · K or more. A circuit structure with a heat radiator having the circuit structure according to any one of claims 1 to 5 and a heat radiator that promotes heat radiation from the circuit structure,
The radiator is disposed on the bus bar side in the stacking direction of the circuit components, and is mechanically fastened to the circuit components,
A heat conductive member having insulation is sandwiched between the circuit component and the heat radiating body,
The heat conductive member is deformed into a shape that matches both the outer surface of the circuit component and the outer surface of the heat radiator. A circuit component with a radiator having the circuit component according to claim 5 and a radiator that promotes heat radiation from the circuit component,
The radiator is disposed on the bus bar side in the stacking direction of the circuit components, is mechanically fastened to the circuit components, and is in contact with the adhesive. Construct.

Images