JP2020161693A - Circuit board and manufacturing method of electric connection box including the same - Google Patents

Abstract

To provide a circuit board which enables an electronic component having a narrow terminal pitch to be mounted thereon, and to provide a manufacturing method of an electric connection box including the circuit board.SOLUTION: In an electric connection box 100, electronic components 5, arranged parallel to each other and each including a first terminal and a second terminal, are mounted on a circuit board 1. The circuit board 1 includes an insulating holding member 2, a conductive plate 3, chip terminals 7, and a signal circuit 6. The conductive plate 3 is held by the holding member 2. The first terminal is joined to the conductive plate 3 and the chip terminal 7 is fitted into a hole formed in a surface of the holding member 2. The second terminal is joined to the chip terminal 7. The signal circuit 6 is formed on a surface of the holding member 2 by a conductive nano ink and an end part of the signal circuit 6 is joined to the chip terminal 7.SELECTED DRAWING: Figure 1

Description

The present invention relates to a circuit board and a method for manufacturing an electrical junction box including the circuit board.

It is composed of a metal plate punched out in a predetermined wiring pattern and a high thermal conductive composite insulating material, and the high thermal conductive composite insulating material is in a state where the metal plate is exposed at least a component mounting portion of the metal plate. A heat-dissipating substrate for mounting electronic components that is integrally formed is known (see, for example, Patent Document 1). The metal plate constituting the heat radiating board (circuit board) for mounting electronic components of Patent Document 1 is punched into a predetermined wiring pattern and at least partially bent or drawn.

Japanese Unexamined Patent Publication No. 09-321395

However, as the size of the electronic component mounted on the circuit board is reduced, the distance between the terminals of the electronic component, that is, the terminal pitch tends to be narrowed, and the circuit board of Patent Document 1 has such a narrow terminal pitch. There is a concern that it will be difficult to mount various electronic components.

An object of the present invention is to provide a circuit board or the like on which an electronic component having a narrow terminal pitch can be mounted.

The circuit board according to one aspect of the present disclosure is a circuit board on which electronic components including the first terminal and the second terminal arranged side by side are mounted.
It is provided with an insulating holding member, a conductive plate, a chip terminal, and a signal circuit.
The conductive plate is held by the holding member and
The first terminal is joined to the conductive plate and
The chip terminal is fitted into a hole formed on the surface of the holding member.
The second terminal is joined to the chip terminal and
The signal circuit is formed on the surface of the holding member by the conductive nanoink.
The end of the signal circuit is joined to the chip terminal.

According to one aspect of the present disclosure, it is possible to provide a circuit board or the like on which an electronic component having a narrow terminal pitch can be mounted.

It is a perspective view of the electric junction box including the circuit board which concerns on Embodiment 1. FIG. It is explanatory drawing which shows the structure of the conductive plate. It is a perspective view of the state in which the conductive plate and the holding member are integrated. It is a top view of the state which the chip terminal and the signal circuit are provided in the mounting plate part of a holding member. It is explanatory drawing of the joint part of a chip terminal and a signal circuit. It is a top view of the electric junction box including a circuit board. It is a schematic cross-sectional view of the main part (AA) of a circuit board. It is a schematic cross-sectional view of the main part (BB) of a circuit board. It is explanatory drawing of the joint part of a chip terminal and a signal circuit in a state where an electronic component is mounted. It is explanatory drawing (A, B) of the electric junction box manufacturing method including a circuit board. It is explanatory drawing (C, D) of the electric junction box manufacturing method including a circuit board. It is explanatory drawing (E, F) of the electric junction box manufacturing method including a circuit board. It is explanatory drawing (G, H) of the electric junction box manufacturing method including a circuit board. It is explanatory drawing (I, J) of the electric junction box manufacturing method including a circuit board.

[Explanation of Embodiments of the present disclosure]
First, embodiments of the present disclosure will be listed and described. In addition, at least a part of the embodiments described below may be arbitrarily combined.

(1) The circuit board according to one aspect of the present disclosure is a circuit board on which electronic components including the first terminal and the second terminal arranged side by side are mounted.
It is provided with an insulating holding member, a conductive plate, a chip terminal, and a signal circuit.
The conductive plate is held by the holding member and
The first terminal is joined to the conductive plate and
The chip terminal is fitted into a hole formed on the surface of the holding member.
The second terminal is joined to the chip terminal and
The signal circuit is formed on the surface of the holding member by the conductive nanoink.
The end of the signal circuit is joined to the chip terminal.

In this embodiment, when mounting the electronic components including the first terminal and the second terminal arranged side by side on the circuit board, the first terminal is joined to the conductive plate and the second terminal is joined to the chip terminal. Since the signal circuit joined to the chip terminals is formed of conductive nanoink, a circuit board on which electronic components with a narrow terminal pitch (distance between terminals) of the first and second terminals arranged side by side are mounted. Can be provided. The conductive plate is held by the holding member, and the signal circuit formed by the chip terminal and the conductive nanoink is provided on the surface of the holding member. Since the holding member is insulating, it is possible to ensure the insulation between the conductive plate, the chip terminal, and the signal circuit.

(2) In the circuit board according to one aspect of the present disclosure, the inner peripheral edge of the hole has a circular shape.
The chip terminal is a disk and
The outer peripheral edge of the disk is fitted into the inner peripheral edge of the hole, and the chip terminal is fitted into the hole.

In this embodiment, the chip terminal is a circular plate, and the inner peripheral edge of the hole formed on the surface of the holding member and the outer peripheral edge of the chip terminal facing the inner peripheral edge of the hole are both circular. Therefore, when manufacturing a circuit board, it is not necessary to match the rotation angle of the outer peripheral edge of the chip terminal with respect to the inner peripheral edge of the hole in the step of fitting the chip terminal into the hole, and the efficiency of the manufacturing process can be improved. it can.

(3) In the circuit board according to one aspect of the present disclosure, the chip terminals are made of copper or an alloy containing copper as a main component.
The conductive nanoink is a conductive copper nanoink in which copper nanoparticles are dispersed in a liquid.

In this embodiment, since the chip terminal is made of copper or an alloy containing copper as a main component (made of copper alloy), the chip terminal and the signal circuit using the conductive nanoink are electrically joined. That is, by firing the conductive copper nanoink on the surface of the chip terminal, the chip terminal and the signal circuit formed by the conductive copper nanoink are electrically connected and conductive. The copper-based alloy is a copper alloy such as C19020 or C19720 having a conductivity of 50% IACS (international annealed copper standard) or more. In the conductive nanoink, a thin film in which copper nanoparticles are densely arranged is formed by coating and drying, and when this is heat-treated, the copper nanoparticles are fused due to the melting point drop peculiar to the copper nanoparticles to form a metal bond. Since the metal bond formed by the formed copper nanoparticles and the chip terminal made of copper or a copper alloy are bonded by the same kind of metal, the bonding strength can be improved. By performing bonding between the same types of metals, the linear expansion coefficient of the signal circuit by the chip terminal and the conductive nano ink can be approximated at the bonding site, and the bonding strength against thermal shock can be improved.

(4) In the circuit board according to one aspect of the present disclosure, the end of the signal circuit formed of the conductive nanoink is provided on the chip terminal.
A missing portion is formed at the end of the signal circuit.
The chip terminal includes an exposed portion exposed from the missing portion.
The exposed portion is coated with solder for joining the chip terminal and the second terminal.
The second terminal is joined to the exposed portion.

In this embodiment, even when the wettability of the conductive nanoink to the solder is low, the second terminal and the chip terminal are directly bonded by bonding the second terminal to the exposed portion of the chip terminal to increase the bonding strength. Can be improved.

(5) In the circuit board according to one aspect of the present disclosure, the end portion of the signal circuit has a concave shape that opens toward the electronic component side due to the missing portion.
The width of the opening is wider than the width of the second terminal joined to the exposed portion.

In this embodiment, since the width of the opening at the end of the signal circuit provided with the missing portion is wider than the width of the second terminal connected to the exposed portion, the second terminal overlaps the end of the signal circuit. This can be prevented and the exposed portion of the second terminal and the chip terminal can be joined to improve the joining strength.

(6) In the circuit board according to one aspect of the present disclosure, one surface of the conductive plate is provided with a convex portion protruding in the perpendicular direction from the one surface.
The first terminal is joined on the convex portion.

In this embodiment, by using the convex portion provided on the conductive plate as a portion for mounting the first terminal, another connecting component (connection point) interposed between the conductive plate and the first terminal is unnecessary. Therefore, the electric resistance between the first terminal and the conductive plate can be reduced, and the amount of heat generated during energization can be suppressed.

(7) The method for manufacturing an electrical junction box including a circuit board according to one aspect of the present disclosure is a method for manufacturing an electrical junction box including a circuit board.
The conductive plate is arranged in the mold, and resin is injected into the mold to form a holding member including an outer frame and a mounting plate portion, and at least a part of the conductive plate is housed in the outer frame. The step of integrating the conductive plate and the holding member so as to
The process of press-fitting the chip terminal and the second chip terminal into the holes provided in the mounting plate portion,
A step of printing a signal circuit that electrically connects the chip terminal and the second chip terminal with conductive nanoink on the mounting plate portion.
A step of applying a solder paste to a predetermined area of the conductive plate and the chip terminal, and
The electronic component is placed in a predetermined area of the conductive plate coated with the solder paste and the chip terminal by aligning the first terminal and the second terminal of the electronic component, respectively, and the electronic component is placed in a reflow furnace. The soldering process and
A step of accommodating a control circuit board for controlling the electronic component in the outer frame and fixing the upper lid and the heat sink so as to close the openings at both ends of the outer frame is included.

In this embodiment, it is possible to provide an electric junction box including a circuit board on which electronic components having a narrow terminal pitch can be mounted.

[Details of Embodiments of the present disclosure]
A specific example of a method of manufacturing the electrical junction box 100 including the circuit board 1 and the circuit board 1 according to the embodiment of the present disclosure will be described below with reference to the drawings. It should be noted that the present disclosure is not limited to these examples, and is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

(Embodiment 1)
FIG. 1 is a perspective view of the electrical junction box 100 including the circuit board 1 according to the first embodiment. FIG. 1 shows a state in which the upper lid 102 of the electrical junction box 100 and the control circuit board 101 (see FIG. 14) are removed in order to explain the circuit board 1. The circuit board 1 is housed in the electric junction box 100. The circuit board 1 includes a holding member 2, an electronic component 5, a conductive plate 3, a second conductive plate 4, a connector terminal 105, and a board connecting connector 106.

The holding member 2 includes a rectangular outer frame 21 forming an outer shell of the electrical connection box 100 and a mounting plate portion 22 on which a signal circuit 6 is formed, and includes a conductive plate 3, a second conductive plate 4, and a connector terminal 105. To hold. The base portion of the circuit board 1 is formed by the mounting plate portion 22, the conductive plate 3, and the second conductive plate 4. An electronic component 5, a chip terminal 7, and a second chip terminal 8 are mounted on the surface of the mounting plate portion 22, and a signal circuit 6 is formed between the chip terminal 7 and the second chip terminal 8. The plurality of electronic components 5 are arranged side by side on the circuit board 1, and the plurality of electronic components 5 are arranged (mounted) so as to straddle the conductive plate 3 and the second conductive plate 4. Each of the plurality of electronic components 5 is connected to the board connection connector 106 by the signal circuit 6.

The control circuit board 101 (see FIG. 14) connected to the board connection connector 106 outputs a control signal for controlling the electronic component 5 via the board connection connector 106, and the output control signal is For example, it is input to an electronic component 5 such as a semiconductor switch. The electronic component 5 (semiconductor switch) that has received the control signal energizes between the conductive plate 3 and the second conductive plate 4 by closing (on) the switch. The electric junction box 100 including the circuit board 1 configured in this way is interposed between a power storage device (not shown) such as a lithium battery mounted on a vehicle and an in-vehicle load (not shown), and is used for a vehicle. It is used as a power supply device for.

FIG. 2 is an explanatory diagram showing the configuration of the conductive plate 3. As described above, the circuit board 1 includes a conductive plate 3 and a second conductive plate 4 as conductive members. FIG. 2 shows the conductive plate 3 and the second conductive plate 4 in a state where the holding member 2 is removed.

The conductive plate 3 is made of a metal having good conductivity, for example, pure copper or a copper alloy (copper or the like), and is called a bus bar. The surface of the conductive plate 3 may be nickel-plated. The conductive plate 3 has a convex shape in a plan view, and includes a thick portion 32 and a thin portion 33 having a thickness smaller than that of the thick portion 32.

A protruding piece portion having a convex shape is formed in the thick portion 32, and a hole is provided in the central portion of the protruding piece portion. As shown in FIG. 1, the protruding piece portion is provided so as to project outward from the outer frame 21, and serves as a fastening portion for electrically connecting to other electric parts when the electric junction box 100 is mounted on the vehicle. Used.

The thin portion 33 has a rectangular shape, and a plurality of convex portions 31 protruding in the vertical direction from the surface of the thin portion 33 are arranged side by side on the edge side of the thin portion 33 on the long side in the lateral direction. Each of the plurality of convex portions 31 forms a rectangle, and the lateral edge of the convex portion 31 (the long side of the convex portion 31) is the edge of the thin portion 33 in the lateral direction (the long side of the thin portion 33). Along, each of the plurality of convex portions 31 is provided on the surface of the thin portion 33. Although the details will be described later, the convex portion 31 is used as a portion for mounting the terminal of the electronic component 5.

The size of the plate thickness (plate width) of the wall-thick portion 32 and the total value of the plate thickness (plate width) of the thin-walled portion 33 and the convex portion 31 are the same. That is, the surface of the thick portion 32 and the upper surface (surface) of the convex portion 31 are located on the same plane and form a so-called flush surface.

The second conductive plate 4 is made of a metal having good conductivity such as copper, and is preferably made of the same material as the conductive plate 3. The surface of the second conductive plate 4 may be nickel-plated. The second conductive plate 4 has a convex shape like the conductive plate 3, and a hole is provided in the central portion of the protruding piece portion in the convex shape. The protruding piece portion of the second conductive plate 4 is also provided so as to project outward from the outer frame 21 like the conductive plate 3, and is electrically connected to other electric parts when the electric connection box 100 is mounted on the vehicle. Used as a fastening part for

The conductive plate 3 and the second conductive plate 4 are arranged so that the side surfaces in the longitudinal direction in which the protruding piece portion is not provided face each other. That is, a gap is formed between the side surface in the longitudinal direction in which the protruding piece portion of the conductive plate 3 is not provided and the side surface in the longitudinal direction in which the protruding piece portion of the second conductive plate 4 is not provided. .. The conductive plate 3 and the second conductive plate 4 are arranged so as to be in a non-contact state by the gap. The gap is filled with the resin constituting the holding member 2, and the insulation of the conductive plate 3 and the second conductive plate 4 is ensured. The surface of the thick portion 32 of the conductive plate 3 and the surface of the second conductive plate 4 are located on the same plane and form a so-called flush surface.

FIG. 3 is a perspective view showing a state in which the conductive plate 3 and the holding member 2 are integrated. The conductive plate 3, the second conductive plate 4, and the two L-shaped connector terminals 105 are held by a holding member 2 made of an insulating resin.

The conductive plate 3 and the second conductive plate 4 are fixed in the mold in the arrangement as shown in FIG. 2, and the connector terminal 105 is further fixed in the mold, and the holding member 2 is attached to the mold. A circuit board 1 (bass bar insert board) in which a conductive plate 3, a second conductive plate 4, a connector terminal 105, and a holding member 2 (mounting plate portion 22) are integrated is configured by insert molding in which a resin as a material is injection-molded. Will be done.

The holding member 2 is molded from an insulating resin, and the resin is a thermoplastic resin such as PPS (polyphenylene sulfide). The holding member 2 includes an outer frame 21 and a mounting plate portion 22.

The outer frame 21 forms a rectangular frame and forms the outer shell of the electrical connection box 100. A circuit board 1 composed of a conductive plate 3, a second conductive plate 4, and a mounting plate portion 22 is located inside the outer frame 21.

The mounting plate portion 22 has a rectangular shape and is provided between the thick portion 32 of the conductive plate 3 and the second conductive plate 4. That is, the mounting plate portion 22 is laminated so as to cover the surface of the thin portion 33 of the conductive plate 3. Therefore, the shape and area of the surface of the mounting plate portion 22 are the same as the shape and area of the surface of the thin portion 33 of the conductive plate 3. The wall thickness of the mounting plate portion 22 is set so that the upper surface (surface) of the convex portion 31 projecting from the thin portion 33 of the conductive plate 3 is exposed. Therefore, the surface of the thick portion 32 of the conductive plate 3, the surface of the mounting plate portion 22, the upper surface (surface) of the convex portion 31 projecting from the thin portion 33 of the conductive plate 3, and the surface of the second conductive plate 4 , Located on the same plane, forming a so-called flush form.

A plurality of fitting holes 221 are provided on the surface of the mounting plate portion 22. The fitting hole 221 includes a fitting hole 221 in which the chip terminal 7 is fitted and a fitting hole 221 in which the second chip terminal 8 is fitted.

The fitting holes 221 into which the chip terminals 7 are fitted are provided between the convex portions 31 arranged side by side. That is, the convex portions 31 and the fitting holes 221 are arranged side by side so as to alternate along the longitudinal direction of the mounting plate portion 22. The inner peripheral edge of the fitting hole 221 has a circular shape. The diameter of the inner peripheral edge of the fitting hole 221 is smaller than the length of the adjacent convex portion 31 in the lateral direction.

The fitting holes 221 into which the second chip terminals 8 are fitted are arranged side by side along the short side (short side) on the end side (near each short side) of the mounting plate portion 22 in the longitudinal direction. ing. The inner peripheral edge of the fitting hole 221 into which the second chip terminal 8 is fitted has a circular shape, and the diameter of the inner peripheral edge is the same as the diameter of the fitting hole 221 in which the chip terminal 7 is fitted.

A tubular connector housing 23 is provided on the outer peripheral surface of the outer frame 21. A hole for inserting the connector terminal 105 is provided in the place of the outer frame 21 where the connector housing 23 is provided, and the connector terminal 105 is provided inside the connector housing 23 so as to penetrate the outer frame 21. It enables electrical connection inside and outside the outer frame 21.

FIG. 4 is a plan view showing a state in which the chip terminal 7 and the signal circuit 6 are provided on the mounting plate portion 22 of the holding member 2. The mounting plate portion 22 is provided with a chip terminal 7, a second chip terminal 8, and a signal circuit 6. The chip terminals 7 are fitted into fitting holes 221 arranged side by side along the longitudinal direction (long side) of the mounting plate portion 22. The second chip terminal 8 is fitted into the fitting holes 221 arranged side by side along the lateral direction (short side) of the mounting plate portion 22.

The chip terminal 7 and the second chip terminal 8 are formed of a circular plate (disk) made of a metal having good conductivity such as copper. The outer diameter of the disk is the same as the inner diameter of the fitting hole 221 or the outer diameter of the disk is slightly larger than the inner diameter of the fitting hole 221. It may be fitted and fitted by press-fitting into 221. Alternatively, the chip terminal 7 and the second chip terminal 8 may be inserted into the fitting hole 221 and fitted, and fixed by, for example, ultrasonic welding. The chip terminal 7 functions as a terminal on the electronic component 5 side, and the second chip terminal 8 functions as a terminal on the control circuit board 101 side on which a control component that outputs a control signal to the electronic component 5 is mounted.

The mounting plate portion 22 is provided with a signal circuit 6 for electrically connecting the chip terminal 7 and the second chip terminal 8. The chip terminal 7 and the second chip terminal 8 corresponding to the chip terminal 7 (the second chip terminal 8 into which the control signal to the electronic component 5 connected to the chip terminal 7 is input) are the mounting plate portion 22. It is electrically connected and conducted by a signal circuit 6 printed (formed) on the surface of the device.

The signal circuit 6 is formed of, for example, conductive copper nano-ink, that is, is formed by printing the conductive copper nano-ink on the surface of the mounting plate portion 22. Conductive copper nanoinks are copper nanoparticles of several to several tens of nanometers dispersed in a liquid. When the conductive copper nanoink is printed (coated and dried) on the surface of the mounting plate portion 22, a thin film in which copper nanoparticles are densely arranged can be obtained. When the copper nanoparticles that have become the thin film (coating film) are heat-treated, the particles are fused to each other due to the melting point drop peculiar to the nanoparticles to form a metal bond. As a result, the coating film obtained by the copper nanoink becomes similar to a metal foil (copper foil). The specific components and compositions of the conductive copper nanoink may be, for example, according to the republication publication of International Publication No. (WO2016 / 199811). The signal circuit 6 printed (formed) on the surface of the mounting plate portion 22 with the conductive copper nanoink has an L shape and electrically connects the chip terminal 7 and the second chip terminal 8. Each end 61 of the signal circuit 6 is located at the location of the chip terminal 7 and the second chip terminal 8.

FIG. 5 is an explanatory diagram of a joint portion between the chip terminal 7 and the signal circuit 6. FIG. 5 is an enlarged view of each end 61 of the signal circuit 6 in FIG. Each end 61 of the signal circuit 6 formed of the conductive copper nanoink has a circular shape having a missing portion 62. The signal circuit 6 is formed so that the diameter of the end portion 61 forming a circle is substantially the same as the outer diameter (diameter) of the chip terminal 7 and the second chip terminal 8. Therefore, the end portion 61 of the circular signal circuit 6 is provided so as to cover the chip terminal 7 and the second chip terminal 8 from the surface side of the mounting plate portion 22. A missing portion 62 (notch portion) is formed at the end portion 61 of the circular signal circuit 6. The end portion 61 of the signal circuit 6 has a concave shape (U-shape / C-shape) that is opened toward the electronic component 5 side by the missing portion 62.

As described above, the end portion 61 of the signal circuit 6 is provided so as to cover the chip terminal 7 and the second chip terminal 8, but the chip terminal 7 and the second chip terminal 8 are mounted by the missing portion 62. The exposed portion 71 exposed to the surface side of the plate portion 22 is included. Although details will be described later, the solder paste 9 is applied to the exposed portion 71 of the chip terminal 7 and the second chip terminal 8.

FIG. 6 is a plan view of the electrical junction box 100 including the circuit board 1. FIG. 6 shows a state in which the electronic component 5 is mounted, and corresponds to a plan view of the electrical junction box 100 including the circuit board 1 shown in FIG. A plurality of electronic components 5 are arranged side by side along the longitudinal direction of the mounting plate portion 22 so as to straddle the second conductive plate 4 and the mounting plate portion 22.

The electronic component 5 includes a rectangular outer peripheral device 54 in which an electric circuit is packaged (included), and a first terminal 51, a second terminal 52, and a third terminal 53 provided so as to project from the peripheral edge portion of the outer peripheral device 54. For example, an n-type FET (Field effect transistor). The first terminal 51 and the second terminal 52 project from the same edge (side, side surface) of the outer peripheral device 54 and are arranged side by side. When the electronic component 5 is an n-type FET, the first terminal 51 corresponds to the source terminal, the second terminal 52 corresponds to the gate terminal, and the third terminal 53 corresponds to the drain terminal (see FIG. 9). The first terminal 51 (source terminal) is joined to the upper surface (surface) of the convex portion 31 of the conductive plate 3 (output side bus bar) with the solder paste 9. The second terminal 52 (gate terminal) is joined to the exposed portion 71 of the chip terminal 7 with the solder paste 9. The third terminal 53 (drain terminal) is joined to the surface of the second conductive plate 4 (input side bus bar) with the solder paste 9.

The second chip terminal 8 is electrically connected to the board connection connector 106 provided on the end side (near each short side) of the mounting plate portion 22 in the longitudinal direction. Like the chip terminal 7, the second chip terminal 8 also includes the exposed portion 71, and the exposed portion 71 of the second chip terminal 8 and the board connection connector 106 are joined by the solder paste 9.

FIG. 7 is a schematic cross-sectional view of a main part (AA) of the circuit board 1. FIG. 7 schematically shows the cross section (AA) in FIG. 6, and is a schematic cross-sectional view including the chip terminal 7. The chip terminal 7 is fitted and fitted into a fitting hole 221 provided in the mounting plate portion 22.

The surface of the second conductive plate 4 (upper surface), the surface of the chip terminal 7 (upper surface), the surface of the mounting plate portion 22, and the surface of the thick portion 32 of the conductive plate 3 (upper surface) are located on the same plane. It constitutes a so-called flush form. The resin constituting the mounting plate portion 22, that is, the resin of the holding member 2, is filled in the gap between the second conductive plate 4 and the conductive plate 3.

The back surface (lower surface) of the second conductive plate 4, the back surface of the resin filled in the gaps between the second conductive plate 4 and the conductive plate 3 (the surface exposed on the back surface side of the second conductive plate 4), and the conductive plate 3 The back surface (lower surface) of the thin portion 33 of the above is located on the same plane and constitutes a so-called flush surface.

The electronic component 5 is mounted on the surface side of the mounting plate portion 22 (the surface side of the base portion of the circuit board 1) so that the outer peripheral device 54 of the electronic component 5 straddles the second conductive plate 4 and the chip terminal 7. When the electronic component 5 is an n-type FET, the second terminal 52 (gate terminal) of the electronic component 5 (n-type FET) is placed on the chip terminal 7 and joined to the chip terminal 7. As described above, the exposed portion 71 of the chip terminal 7 is coated with the solder paste 9, and the second terminal 52 and the chip terminal 7 are joined by the solder paste 9. The third terminal 53 (drain terminal) of the electronic component 5 (n-type FET) is placed on the surface of the second conductive plate 4 (input side bus bar), and is formed by the solder paste 9 applied on the surface. The 3 terminal 53 and the 2nd conductive plate 4 are joined.

A plurality of signal circuits 6 are formed of conductive copper nanoinks on the surface of the mounting plate portion 22. The chip terminal 7 and the end portion 61 of the signal circuit 6 are fixed to each other by firing the conductive copper nanoink forming the signal circuit 6. By firing the conductive copper nanoink on the surface of the chip terminal 7, the chip terminal 7 and the signal circuit 6 formed by the conductive copper nanoink are electrically connected and conductive.

FIG. 8 is a schematic cross-sectional view of a main part (BB) of the circuit board 1. FIG. 8 schematically shows the cross section (BB) in FIG. 6, and is a schematic cross-sectional view including the convex portion 31. The description of the parts common to FIG. 7 will be omitted.

The electronic component 5 is mounted on the surface side of the mounting plate portion 22 (the surface side of the base portion of the circuit board 1) so that the outer peripheral device 54 of the electronic component 5 straddles the second conductive plate 4 and the convex portion 31 of the conductive plate 3. Has been done. The first terminal 51 (source terminal) of the electronic component 5 (n-type FET) is placed on the upper surface (on the surface) of the convex portion 31 of the conductive plate 3, and is formed by the solder paste 9 applied on the surface. The first terminal 51 and the conductive plate 3 are joined.

FIG. 9 is an explanatory diagram of a joint portion between the chip terminal 7 and the signal circuit 6 in a state where the electronic component 5 is mounted. FIG. 9 is an enlarged view of the joint between the end 61 of the signal circuit 6 and the chip terminal 7 in FIG. As described above, the end portion 61 of the signal circuit 6 has a circular shape having a missing portion 62, and is formed so as to cover a part of the surface of the chip terminal 7. That is, the end 61 of the signal circuit 6 joined to the chip terminal 7 is provided with a missing portion 62 (notched portion) in which a part thereof is cut out. The missing portion 62 is provided on the electronic component 5 side. Therefore, the end portion 61 of the signal circuit 6 has a concave shape (U-shape / C-shape) that opens toward the electronic component 5 side due to the missing portion 62.

The exposed portion 71 of the chip terminal 7 exposed from the missing portion 62 is formed on the electronic component 5 side. When the solder paste 9 is applied to the exposed portion 71 of the chip terminal 7, the missing portion 62 forms a concave (U-shaped / C-shaped) opening at the end 61 of the signal circuit 6 to form the exposed portion 71. It is possible to prevent the applied solder paste 9 from flowing out from the exposed portion 71. At the end 61 of the signal circuit 6, the rest of the region other than the missing portion 62 is joined to the chip terminal 7, and the signal circuit 6 and the chip terminal 7 are electrically connected to each other.

In the present embodiment, the end 61 of the signal circuit 6 has a concave shape (C shape) opened toward the electronic component 5 side by the missing portion 62, but the present invention is not limited to this. The missing portion 62 may be a hole provided at the end portion 61 of the circular signal circuit 6. The surface of the chip terminal 7 is exposed from the missing portion 62 formed by the holes provided in the end portion 61, and the exposed portion corresponds to the exposed portion 71 of the chip terminal 7. The shape of the inner peripheral edge of the hole (missing portion 62) provided at the end portion 61 of the signal circuit 6 is the same as the shape of the outer peripheral edge of the exposed portion 71 of the chip terminal 7. Where the solder paste 9 is applied to the exposed portion 71 of the chip terminal 7, the exposed portion 71 of the chip terminal 7 has an outer peripheral edge (closed loop) by forming the missing portion 62 of the end portion 61 of the signal circuit 6 with holes. It becomes a form surrounded by, and it is possible to prevent the applied solder paste 9 from flowing out from the exposed portion 71.

In the present embodiment, the end 61 of the signal circuit 6 is circular and is formed so as to cover the chip terminal 7, but the present invention is not limited to this. The end 61 of the signal circuit 6 may be a polygon such as a rectangle, and may be formed so as to cover the surface of the chip terminal 7.

The second terminal 52 (gate terminal) of the electronic component 5 (n-type FET) has a rectangular shape and is placed on the exposed portion 71 of the chip terminal 7. The width of the second terminal 52 (gate terminal) in the lateral direction (protruding direction from the outer peripheral device 54) is smaller than the width of the opening formed at the end 61 of the signal circuit 6. Therefore, the second terminal 52 (gate terminal) can be placed inside the opening, that is, the second terminal 52 (gate terminal) is placed on the exposed portion of the chip terminal 7 without overlapping the end 61 of the signal circuit 6. It can be placed on 71.

A solder paste 9 is applied to the exposed portion 71 of the chip terminal 7, and the chip terminal 7 and the second terminal 52 (gate terminal) are joined by the solder paste 9. By forming the joint between the second terminal 52 (gate terminal) and the chip terminal 7 in such a joining form, it is not necessary to join the second terminal 52 (gate terminal) and the signal circuit 6 with the solder paste 9. Can be. When the signal circuit 6 is formed of the conductive copper nanoink as in the present embodiment, the wettability of the conductive copper nanoink to the solder is low when the conductive copper nanoink does not contain a component that functions as a flux. However, a missing portion 62 is provided at the end 61 of the signal circuit 6 formed of the conductive copper nanoink, and the exposed portion 71 of the chip terminal 7 exposed from the missing portion 62 and the second terminal 52 (gate terminal) are solder-pasted. The joining force can be ensured by joining at 9.

According to this embodiment, since the signal circuit 6 joined to the chip terminal 7 is formed of conductive copper nanoink, the terminal pitch (distance between the terminals) of the first terminal 51 and the second terminal 52 arranged side by side. ) Can provide a circuit board 1 on which a narrow electronic component 5 is mounted.

When the electronic component 5 is an n-type FET, the second terminal 52 (gate terminal) into which the control signal is input is electrically connected to the signal circuit 6 formed of the conductive copper nanoink via the chip terminal 7. Therefore, the bus bar for the second terminal 52 (gate terminal) can be eliminated. The size of the end 61 of the chip terminal 7 and the signal circuit 6 is smaller than that of a plate member such as a bus bar. Therefore, the electronic component 5 having a small terminal pitch between the first terminal 51 (source terminal) joined to the conductive plate 3 (output bus bar) and the second terminal 52 (gate terminal) joined to the chip terminal 7 is conductive. It can be mounted on a circuit board 1 (bass bar insert board) that is insert-molded using the board 3 and the second conductive board 4.

The chip terminal 7 is a circular plate, and the fitting hole 221 into which the chip terminal 7 is fitted also has a circular shape. Therefore, when manufacturing the circuit board 1, in the step of press-fitting the chip terminal 7 into the fitting hole 221, it is not necessary to match the rotation angle of the outer peripheral edge of the chip terminal 7 with respect to the inner peripheral edge of the hole, and the efficiency of the manufacturing process is improved. Can be achieved.

The end 61 of the signal circuit 6 printed (formed) by the conductive copper nanoink is provided so as to cover the surface of the chip terminal 7, and the end 61 of the signal circuit 6 is provided with a missing portion 62. .. Due to the missing portion 62, the end portion 61 of the signal circuit 6 has a concave shape that opens toward the electronic component 5 side. Therefore, the missing portion 62 forms an exposed portion 71 on the surface of the chip terminal 7 on which the conductive copper nanoink is not printed. Since the solder paste 9 for joining the chip terminal 7 and the second terminal 52 is applied to the exposed portion 71, even when the conductive copper nanoink (conductive nanoink) has low wettability to solder. , The second terminal 52 and the chip terminal 7 can be directly bonded with the solder paste 9 to improve the bonding strength.

By using the convex portion 31 provided on the conductive plate 3 as a portion for mounting the first terminal 51, other connecting parts (connection points) interposed between the conductive plate 3 and the first terminal 51 are unnecessary. Therefore, the electric resistance between the first terminal 51 of the electronic component 5 and the conductive plate 3 can be reduced, and the amount of heat generated during energization can be suppressed.

10, FIG. 11, FIG. 12, FIG. 13 and FIG. 14 are explanatory views of a method of manufacturing the electrical junction box 100 including the circuit board 1. A method of manufacturing the electrical junction box 100 including the circuit board 1 according to the first embodiment will be described below with reference to FIGS. 10, 11, 12, 13, and 14.

First, the side surfaces (edges) of the conductive plate 3 (output bus bar) and the second conductive plate 4 (input bus bar) are opposed to each other, and the side surfaces are spaced apart from each other and arranged side by side in this order (see FIG. 10A). The conductive plate 3 and the second conductive plate 4 are produced, for example, by cutting or pressing a plate material of pure copper or a copper alloy having a plate thickness of 2 mm to 3 mm. The surfaces of the conductive plate 3 and the second conductive plate 4 may be nickel-plated. A convex portion 31 is provided on the edge side of the surface of the conductive plate 3 in the lateral direction, for example, by cutting or pressing. In the conductive plate 3, the edge of the convex portion 31 is opposed to the edge of the second conductive plate 4 in the lateral direction. Further, a connector terminal 105 is prepared.

Next, the conductive plate 3, the second conductive plate 4, and the connector terminal 105 are arranged in the insert molding die and integrally molded by an injection molding machine. As the molding resin, for example, a thermoplastic resin having high heat resistance such as PPS (polyphenylene sulfide) is used (see FIG. 10B). The outer frame 21 forming the outer shell of the electrical connection box 100 is formed so as to have a case shape. The upper surface (surface) of the convex portion 31 of the conductive plate 3, the surface of the thick portion 32 of the conductive plate 3 and the surface of the second conductive plate 4 are exposed, and each of these surfaces and the surface of the thin portion 33 of the conductive plate 3 are exposed. The mounting plate portion 22 is formed so that the surface (mounting surface) of the mounting plate portion 22 formed of resin on the surface is flush with the same plane (plane). The conductive plate 3, the second conductive plate 4, and the mounting plate portion 22 formed on the same plane in this way form a base portion of the circuit board 1 (bus bar insert substrate). A plurality of fitting holes 221 are formed on the surface of the mounting plate portion 22. These plurality of fitting holes 221 are formed according to the position of the second terminal 52 of the electronic component 5 to be mounted later or the position of the board connection connector 106.

Next, the chip terminal 7 made of pure copper or a copper alloy is press-fitted into the fitting hole 221 formed in the mounting plate portion 22, and the chip terminal 7 is fitted into the fitting hole 221 (see FIGS. 11C and D). In the merging step, the chip terminal 7 may be press-fitted into the fitting hole 221 using an ultrasonic vibration press-fitting machine and fixed to the mounting plate portion 22. The chip terminal 7 is press-fitted into the fitting hole 221 so that the upper surface (surface) of the chip terminal 7 is flush with the surface of the mounting plate portion 22 (flat). Since the chip terminal 7 is a circular plate and the inner peripheral edge of the fitting hole 221 is also circular, when the chip terminal 7 is press-fitted into the fitting hole 221, the chip terminal 7 is pressed against the inner peripheral edge of the fitting hole 221. It is not necessary to adjust the angle of the outer peripheral edge, and the time required for the merging process can be reduced.

Next, using a screen printing machine, conductive copper nanoink is printed in the shape of the signal circuit 6 on the surface (mounting surface) of the mounting plate portion 22 formed of resin (see FIG. 12E). The conductive copper nanoink has a characteristic that it is melted by firing to exhibit conductivity, and the melting point of a metal such as copper is dramatically lowered due to ultrafine particles. Therefore, copper wiring is formed by firing at a temperature of about 120 ° C., and a signal circuit 6 capable of electrical bonding is formed.

The conductive copper nanoink (end 61 of the signal circuit 6) on the chip terminal 7 is printed so as to cover a part of the surface of the chip terminal 7. Conductive copper so that the shape of the conductive copper nanoink on the chip terminal 7 (the shape of the end 61 of the signal circuit 6) is concave (U-shaped / C-shaped) that opens toward the second conductive plate 4 side. Print the nanoink (see Figure 5). The exposed portion 71 of the chip terminal 7 is formed by the region on the surface of the chip terminal 7 on which the conductive copper nanoink is not printed.

The region on the chip terminal 7 where the conductive copper nanoink is not printed corresponds to the missing portion 62 at the end 61 of the signal circuit 6. The region on which the conductive copper nanoink is printed on the chip terminal 7 corresponds to the remaining portion (the region covering a part of the surface of the chip terminal 7) at the end 61 of the signal circuit 6. That is, the signal circuit 6 and the chip terminal 7 are electrically connected by joining the remaining portion of the end 61 of the signal circuit 6 with the chip terminal 7.

The conductive copper nanoink (end 61 of the signal circuit 6) on the second chip terminal 8 is printed so as to cover a part of the surface of the second chip terminal 8 like the chip terminal 7. The shape of the conductive copper nanoink on the second chip terminal 8 (the shape of the end portion 61 of the signal circuit 6) is concave (U-shaped / C-shaped) that opens in the direction opposite to the wiring direction of the signal circuit 6. The conductive copper nanoink is printed in this manner (see FIG. 5). Similar to the chip terminal 7, the exposed portion 71 of the second chip terminal 8 is formed by the area on the surface of the second chip terminal 8 on which the conductive copper nanoink is not printed.

Next, the solder paste 9 is applied to the exposed portion 71 of the chip terminal 7, the predetermined portion on the upper surface of the convex portion 31 of the conductive plate 3, and the predetermined portion on the upper surface of the second conductive plate 4 (see FIG. 12F). A plurality of electronic components 5 (seven in the drawing) are arranged side by side so that the terminals (51, 52, 53) are placed on the coated solder paste 9, and each of these electronic components 5 is arranged. It is mounted so as to straddle the convex portion 31 of the second conductive plate and the conductive plate 3. Therefore, the plurality of electronic components 5 are arranged side by side along the boundary line between the mounting plate portion 22 and the second conductive plate 4.

The electronic component 5 is a semiconductor switch such as an n-type FET. When the electronic component 5 is an n-type FET, the first terminal 51 (source terminal) is placed on the convex portion 31 of the conductive plate 3 in the region where the solder paste 9 is applied. The second terminal 52 (gate terminal) is placed on the exposed portion 71 of the chip terminal 7 in the area where the solder paste 9 is applied. The third terminal 53 (drain terminal) is placed on the second conductive plate 4 in the region where the solder paste 9 is applied.

Further, each board connection connector 106 is aligned with the second chip terminal 8 provided on the end side (near the short side) in the longitudinal direction of the mounting plate portion 22 and is placed on the surface of the mounting plate portion 22. Implement. A state in which a plurality of electronic components 5 and a board connection connector 106 are mounted is soldered in a reflow furnace. As a result, an electric junction box 100 that includes (stores) the circuit board 1 (bus bar insert board) on which the electronic component 5 is mounted is generated (see FIG. 13G).

Next, the control circuit board on which the microcomputer or the like is mounted is fitted inside the outer frame 21, and the terminals (not shown) of the control circuit board and the connector terminals 105 are joined by solder and electrically connected (FIG. 13H). reference). By fitting the control circuit board inside the outer frame 21, the signal terminal provided on the control circuit board is joined to the board connection connector 106, and the voltage (duty) that becomes the control signal output from the control circuit board. ) Is applied (input) to the second terminal 52 (gate terminal) of the electronic component 5 (n-type FET). By joining the terminals of the control circuit board and the connector terminals 105 with solder, a signal transmitted from the outside of the electrical junction box 100 is input to the control circuit board, and the microcomputer on the control circuit board that receives the signal receives the signal. A control signal can be output to the electronic component 5 to enable on / off operation of the electronic component 5 (n-type FET).

Next, the heat sink 103 using a metal having high heat conductivity such as aluminum is fixed to the holding member 2 with screws (see FIG. 14I). A thin plate-shaped or sheet-shaped heat radiating material 104 (heat transfer promoting material) is provided on the surface of the heat sink 103. The heat radiating material 104 has an insulating property, and while insulating the heat sink 103 and the conductive plate 3 and the second conductive plate 4, they are brought into contact with each other to be thermally connected. When fixing the heat sink 103 to the holding member 2, the front surface of the heat radiating material 104 is brought into contact with the back surfaces of the conductive plate 3 and the second conductive plate 4, and the heat sink 103 is fixed to the holding member 2 with screws. The heat radiating material 104 is interposed between the heat sink 103 and the conductive plate 3 and the second conductive plate 4, and the conductive plate 3 and the second conductive plate 4 and the heat sink 103 are heated via the heat radiating material 104. Is connected. Therefore, the heat generated by the electronic component 5 or the like can be transferred to the heat sink 103 via the conductive plate 3 and the second conductive plate 4, and the heat dissipation can be improved.

Next, the upper lid 102 is fixed to the holding member 2 (see FIG. 14I). The electrical connection box 100 is completed by fixing the upper lid 102 to the holding member 2 so as to cover the conductive plate 3 and the second conductive plate 4 from the surface side. (See Fig. 14J)

According to this manufacturing method, it is possible to efficiently manufacture the electric junction box 100 including the circuit board 1 on which the electronic component 5 having a narrow terminal pitch can be mounted.

When the electronic component 5 is a semiconductor switch such as an n-type FET, a metal formed by printing conductive copper nanoink on the mounting plate portion 22 instead of the bus bar for connecting the second terminal 52 (gate terminal). Use a membrane. As a result, the end 61 of the signal circuit 6 connected to the second terminal 52 (gate terminal) can be arranged in the vicinity of the conductive plate 3 (output bus bar) connecting the first terminal 51 (source terminal). .. Therefore, the electronic component 5 having a narrow pitch between terminals can be mounted on the circuit board 1 (bus bar insert board) generated by the insert molding, and the miniaturized electric junction box 100 can be manufactured by the high-density mounting.

The embodiments disclosed this time should be considered as exemplary in all respects and not restrictive. The scope of the present disclosure is indicated by the scope of claims, not the above-mentioned meaning, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Circuit board 2 Holding member 21 Outer frame 22 Mounting plate 221 Fitting hole (hole)
23 Connector housing 3 Conductive plate (output bus bar)
31 Convex part 32 Thick part 33 Thin part 4 Second conductive plate (input bus bar)
5 Electronic components (n-type FET)
51 1st terminal (source terminal)
52 Second terminal (gate terminal)
53 Third terminal (drain terminal)
54 Outer peripheral 6 Signal circuit 61 End 62 Missing part 7 Chip terminal 71 Exposed part 8 Second chip terminal 9 Solder paste 100 Electrical junction box 101 Control circuit board 102 Top lid 103 Heat sink 104 Heat dissipation material 105 Connector terminal 106 Board connection connector

Claims (7)

A circuit board on which electronic components including the first terminal and the second terminal arranged side by side are mounted.
It is provided with an insulating holding member, a conductive plate, a chip terminal, and a signal circuit.
The conductive plate is held by the holding member and
The first terminal is joined to the conductive plate and
The chip terminal is fitted into a hole formed on the surface of the holding member.
The second terminal is joined to the chip terminal and
The signal circuit is formed on the surface of the holding member by the conductive nanoink.
The end of the signal circuit is a circuit board joined to the chip terminal. The inner peripheral edge of the hole has a circular shape.
The chip terminal is a disk and
The circuit board according to claim 1, wherein the outer peripheral edge of the disk is fitted into the inner peripheral edge of the hole, and the chip terminal is fitted into the hole. The chip terminal is made of copper or an alloy containing copper as a main component, and is made of copper.
The circuit board according to claim 1 or 2, wherein the conductive nanoink is a conductive copper nanoink in which copper nanoparticles are dispersed in a liquid. The end of the signal circuit formed by the conductive nanoink is provided on the chip terminal.
A missing portion is formed at the end of the signal circuit.
The chip terminal includes an exposed portion exposed from the missing portion.
The exposed portion is coated with solder for joining the chip terminal and the second terminal.
The circuit board according to any one of claims 1 to 3, wherein the second terminal is joined to the exposed portion. Due to the missing portion, the end portion of the signal circuit has a concave shape that opens toward the electronic component side.
The circuit board according to claim 4, wherein the width of the opening is wider than the width of the second terminal joined to the exposed portion. One surface of the conductive plate is provided with a convex portion protruding in the perpendicular direction from the one surface.
The circuit board according to any one of claims 1 to 5, wherein the first terminal is joined on the convex portion. A method of manufacturing an electrical junction box that includes a circuit board.
The conductive plate is arranged in the mold, and resin is injected into the mold to form a holding member including an outer frame and a mounting plate portion, and at least a part of the conductive plate is housed in the outer frame. The step of integrating the conductive plate and the holding member so as to
The process of press-fitting the chip terminal and the second chip terminal into the holes provided in the mounting plate portion,
A step of printing a signal circuit that electrically connects the chip terminal and the second chip terminal with conductive nanoink on the mounting plate portion.
A step of applying a solder paste to a predetermined area of the conductive plate and the chip terminal, and
The electronic component is placed in a predetermined area of the conductive plate coated with the solder paste and the chip terminal by aligning the first terminal and the second terminal of the electronic component, respectively, and the electronic component is placed in a reflow furnace. The soldering process and
An electric junction box including a circuit board including a step of accommodating a control circuit board for controlling the electronic components in the outer frame and fixing an upper lid and a heat sink so as to close openings at both ends of the outer frame. Production method.

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