JP2007088020A - Circuit structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit structure that can avoid dislocation of an electronic component when a reflow processing is performed. <P>SOLUTION: Grooves 28 are disposed along outer edges of a drain-side connection 27A. Thus, solder S melted upon reflow stops at inner sides of the grooves 28, and it does not flow out any more. Dislocation of a semiconductor switching element 31 can be prevented by inhibiting flow-out of solder S. The grooves 28 are formed only in positions along two confronted sides in the outer edges of the drain-side connection 27A. Consequently, formation of a solder fillet can be confirmed in two remaining sides where the grooves 28 are not arranged, and connection reliability can be secured. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a circuit structure.

  Conventionally, in order to distribute power from an in-vehicle power supply to various electrical components, electronic components such as switching elements are mounted on a circuit pattern formed on one surface of the circuit board, and on the other surface of the circuit board, An electric junction box is used in which a circuit structure in which a bus bar that is electrically connected to a switching element and that constitutes a power circuit is bonded via an insulating layer is housed in a waterproof case (see Patent Document 1). ).

The switching element is provided with a control terminal connected to a control circuit composed of a circuit pattern and a control element, and a power terminal connected to a power circuit. Of these, the power terminal is connected to the bus bar. That is, the circuit board is provided with an opening, and the bus bar is exposed at the bottom of the opening. The exposed surface is plated to ensure electrical continuity with the terminals. A power terminal is inserted into the opening and soldered to the bus bar. This soldering is generally performed by reflow soldering.
JP 2003-164039 A

In the reflow soldering as described above, the solder is applied to a relatively wide area in consideration of the wettability of the solder at the time of melting and the formation of a good solder fillet at the time of solidification.
However, when the solder is applied to a relatively wide area as described above, the terminals of the electronic component may move on the molten solder during reflow, and the electronic component may be displaced.
For this reason, by taking measures such as widening the circuit pattern, etc., it has been possible to cope with such misalignment of the electronic component, but it has been desired to enable more accurate positioning of the electronic component. .

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a circuit structure capable of avoiding misalignment of an electronic component when a reflow process is performed.

  The circuit structure according to the invention of claim 1 for solving the above-described problem is a circuit structure including a conductive path and an electronic component including a terminal and soldered to the conductive path. The conductive path is characterized in that a recess is provided around a solder adhesion region to which solder for soldering the terminal adheres.

  According to a second aspect of the present invention, a circuit board having a conductive path formed on at least one surface side, an electronic component having a terminal and mounted on the one surface side of the circuit board, and the other surface side of the circuit board are provided. The circuit board is formed with an opening penetrating in the thickness direction, and the terminal is soldered to an exposed surface of the bus bar facing the opening. A concave portion is provided around a solder adhesion region to which solder for soldering the terminal adheres on the surface.

  A third aspect of the present invention is the circuit structure according to the first or second aspect, wherein the recess is formed only in a part around the solder adhesion region.

  Invention of Claim 4 is a circuit structure in any one of Claims 1-3, Comprising: Several solder adhesion area | regions are provided in parallel, and the solder adhesion which adjoins in the outer edge of the said solder adhesion area | region The concave portion is provided at a position facing the region.

  A fifth aspect of the present invention is the circuit structure according to the fourth aspect of the present invention, wherein the concave portion is shared by a plurality of the solder attachment regions adjacent to each other.

  According to invention of Claim 1 and Claim 2, the recessed part is provided in the circumference | surroundings of the solder adhesion area | region. According to such a configuration, the solder melted at the time of reflow stops on the inner side of the concave portion and does not flow further outward. In this manner, by preventing the solder from flowing out (diffusion), it is possible to prevent the positional displacement of the electronic component.

  According to invention of Claim 3, the recessed part is formed only in a part of circumference | surroundings of a solder adhesion area | region. Here, the formation state of the solder fillet at the time of soldering serves as a measure of connection reliability and is used for determining the quality of soldering. However, it is difficult to form this solder fillet at the position where the recess is provided. . However, in the present invention, since the concave portion is formed only in a part of the outer edge of the solder adhesion region, the solder fillet is favorably formed at a position where the concave portion is not formed. Thereby, connection reliability is securable.

  According to the invention of claim 4, a plurality of solder adhesion regions are provided in parallel, and a recess is provided at a position facing the adjacent solder adhesion region at the outer edge of the solder adhesion region. According to such a configuration, it can be avoided that one electronic component is displaced toward the adjacent electronic component side and has an adverse effect.

  According to invention of Claim 5, the recessed part is shared by the several solder adhesion area | region which mutually adjoins. According to such a configuration, it is possible to regulate the displacement of a plurality of adjacent electronic components by one concave portion, so that the structure can be simplified and the manufacturing efficiency can be improved.

<First Embodiment>
Hereinafter, a first embodiment embodying the present invention will be described in detail with reference to FIGS. The electrical junction box 1 of the present embodiment is one in which the circuit structure 20 is accommodated in the case 10.

The case 10 of the electrical junction box 1 includes a lower case 11 and an upper case 13 assembled from above the lower case 11 (see FIG. 1).
The lower case 11 includes a frame body 12 formed of an insulating material such as a synthetic resin. The frame body 12 is formed in a frame shape substantially along the peripheral edge of the circuit structure body 20, and the circuit structure body 20 can be fitted almost tightly inside the frame body 12. Although not shown in detail in the frame body 12, a heat radiating plate for radiating heat generated from electronic components provided in the circuit structure 20 is attached.

  The upper case 13 is formed of a synthetic resin in the shape of a shallow dish whose bottom surface is opened as a whole, and is assembled to the lower case 11 while covering the upper side of the circuit structure 20. Openings are provided on both the front and rear surfaces of the upper case 13, and the PCB connector 14 and the fuse box 15 are mounted so as to close the openings.

  The PCB connector 14 assembled to the front end of the upper case 13 is formed in a horizontally long shape opened to the front surface by a synthetic resin. In the PCB connector 14, an external terminal (not shown) connected to the circuit structure 20 faces. The fuse box 15 assembled on the rear end side of the upper case 13 is made of synthetic resin, covers the entire rear surface side of the upper case 13 over its entire length, and its upper half is above the ceiling surface of the upper case 13. It is formed in a horizontally long shape that protrudes. In the fuse box 15, a bus bar terminal 22 </ b> A provided on a bus bar substrate 22 described later is accommodated. In the fuse box 15, an upper connector 16 is assembled from the front to a portion protruding above the upper case 13, and a mating connector (not shown) is fitted from the front side. Yes.

  As shown in FIG. 2, the circuit structure 20 accommodated in the case 10 includes a control circuit board 21 and a bus bar board 22 arranged on the lower surface side of the control circuit board 21. As shown in FIG. 2, the control circuit board 21 has a rectangular plate shape as a whole and is formed in an outer shape with a corner on the left front end side dropped, and a conductor pattern (not shown) is formed on the upper surface side. Is formed.

  A bus bar substrate 22 is attached to the lower surface side of the control circuit board 21 via a thin adhesive sheet 23 having insulating properties (see also FIG. 5). The bus bar substrate 22 is formed by punching a plated metal plate containing tin on the surface, and a plurality of bus bars 24 forming a conductive path serving as a power circuit are arranged in parallel to form a control circuit substrate as a whole. 21 and the outer shape almost matched. A plurality of bus bar terminals 22 </ b> A protrude from the rear edge of the bus bar substrate 22 side by side.

  Electronic components (for example, a semiconductor switching element 31 and a mechanical relay switch 35) are mounted on the upper surface side of the circuit structure 20. Of the electronic components, the semiconductor switching element 31 includes a housing 32 and a plurality of terminals 33 provided on the housing 32 (see also FIGS. 4 and 5). Among the plurality of terminals 33, the drain terminal (power terminal) 33 </ b> A is provided on the entire lower surface side of the housing 32. The source terminal (power terminal) 33B and the gate terminal (control terminal) 33C are projected from the side surface of the housing 32 and bent downward in a crank shape, and their tips are the surfaces of the control circuit board 21 or the bus bar board 22. It is arranged along.

  On the other hand, the mechanical relay switch 35 includes a housing 36 and a plurality of terminals 37 connected to the housing 36. These terminals include a power terminal that is connected to the bus bar board 22 and controls the power circuit, and a control terminal that is connected to the control circuit board 21 and controls the driving of the mechanical relay switch 35. Each terminal 37 protrudes from the bottom of the housing 36 and extends downward, and then is bent outward at a right angle, and its tip is arranged along the surface of the control circuit board 21 or the bus bar board 22.

  Of these terminals 33 and 37 of the electronic components, the power terminals are connected to the bus bar substrate 22 and the control terminals are connected to the land portions 25 provided on the conductor pattern of the control circuit board 21 by soldering. Hereinafter, the connection of each terminal 33 in the semiconductor switching element 31 will be described as an example (see FIGS. 3 and 4).

  In the control circuit board 21, an opening 26 is formed penetrating in the thickness direction at the mounting position of the semiconductor switching element 31, and the bus bar board 22 is exposed from the opening 26. The opening 26 includes a rectangular large hole 26A that is slightly larger than the outer shape viewed from above the semiconductor switching element 31, and a rectangular small hole that is provided on one side of the source switching element 31B and can be inserted into the rectangular hole 26A. 26B is connected to the bus bar substrate 22, and when stacked with the bus bar substrate 22, the bus bar is connected to the bus bar 24 to which the drain terminal 33A is connected and the bus bar 24 to which the source terminal 33B is connected. Yes.

On the surface of each bus bar 24, the regions exposed in the large hole portion 26A and the small hole portion 26B are drain side connection portions 27A (on which solder S for connecting the drain terminals 33A and the source terminals 33B is placed, respectively. Corresponding to the solder adhesion region of the present invention) and the source side connection portion 27B. Of these, on the outer edge of the drain-side connecting portion 27A, groove portions 28 are provided over the entire length of each side at two locations along two opposing sides.
On the other hand, the gate terminal 33C is connected to the land portion 25 provided on the control circuit board 21 by soldering.

In order to manufacture such a circuit structure 20, first, a bus bar substrate 22 is formed by stamping a metal plate plated with tin containing on the surface thereof by pressing (FIG. 5A). Although not shown in detail, at the time of punching, the bus bars 24 and the bus bars 24 and the outer frame surrounding the bus bars 24 are connected by connecting pieces so that the bus bars 24 constituting the bus bar substrate 22 are not separated. It is in a state.
Next, the groove layer 28 is formed by scraping the plated layer 22B on the surface of the bus bar substrate 22 with a laser (FIG. 5B).

  Next, the control circuit board 21 is affixed to the surface side of the bus bar board 22 where the groove 28 is provided via the adhesive sheet 23 (FIG. 5C). The adhesive sheet 23 is provided with a through hole 23A penetrating in the thickness direction at a position aligned with the opening 26 of the control circuit board 21, and the surface of the bus bar substrate 22 is exposed in the opening 26. It is like that. In addition to this bonding step, the bus bar terminal 22A may be bent within a range that does not interfere with the next component mounting step.

  Next, electronic components are mounted on the control circuit board 21. Here, a description will be given taking the mounting of the semiconductor switching element 31 as an example. First, the cream solder S is applied to the land portion 25 of the control circuit board 21 and the connection portion 27 in the opening 26 by, for example, screen printing (FIG. 5D). As this cream solder S, a lead-free type is used. The semiconductor switching element 31 includes a drain terminal 33A in the drain side connection portion 27A in the large hole portion 26A, a source terminal 33B in the source side connection portion 27B in the small hole portion 26B, and a land portion of the control circuit board 21. 25 so that the gate terminal 33C is aligned with 25 and placed on the control circuit board 21 (FIG. 5E). In this state, the circuit component 20 is placed in a reflow furnace (not shown), heated to the solder melting temperature, and then cooled to solder the terminals 33 (FIG. 5F).

  At this time, since the melting temperatures of the solder and tin are extremely close, not only the cream solder S but also the plating layer 22B may melt during reflow. However, in the present embodiment, the groove portions 28 are provided at two locations along the outer edge of the drain side connection portion 27A, which has a particularly large area and is likely to be affected by the positional deviation, among the connection portions 27A and 27B. Since the drain-side connecting portion 27A and the region outside it are divided, the melted cream solder S does not spread out outside the groove 28. By preventing the solder S from flowing out in this way, the positional deviation of the semiconductor switching element 31 associated therewith can be prevented.

  Here, the formation state of the solder fillet at the time of soldering serves as a measure of connection reliability and is used for determining the quality of soldering. However, if the groove 28 is provided on the outer edge, it is difficult to form this solder fillet. Become. Therefore, in the present embodiment, the groove portion 28 is formed only at a part of the outer edge of the drain side connection portion 27A, that is, at a position along two opposing sides of the four sides. In this way, the solder fillet is well formed on the remaining two sides where the groove 28 is not formed, so that connection reliability can be ensured.

  When the mounting of the electronic components is completed, the circuit structure 20 is completed by bending the bus bar terminals 22A and separating the bus bars 24 from each other and the bus bar 24 and the frame. Finally, the circuit structure 20 is accommodated in the case 10 and the PCB connector 14 and the fuse box 15 are assembled to complete the electrical junction box 1.

  As described above, according to the present embodiment, the groove portion 28 is provided along the outer edge of the drain side connection portion 27A. According to such a configuration, the solder S melted at the time of reflow stops inside the groove portion 28 and does not flow further outside. By preventing the solder S from flowing out (diffusing) in this way, it is possible to prevent the positional deviation of the semiconductor switching element 31 associated therewith.

  Moreover, the groove part 28 is formed only in the position along two opposing sides among the outer edges of the drain side connection part 27A. Therefore, formation of solder fillets can be confirmed on the remaining two sides where the groove 28 is not provided, and connection reliability can be ensured.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  As in the first embodiment, the circuit configuration body 40 according to the present embodiment is obtained by attaching a bus bar substrate in which a plurality of bus bars 42 are arranged in parallel to the back side of the control circuit substrate 41. Although not shown in detail on the side surface, electronic components similar to those of the first embodiment are mounted.

  An opening 43 is formed in the control circuit board 21 at the mounting position of the semiconductor switching element 31. In the present embodiment, two semiconductor switching elements 31 are mounted in parallel in one opening 43. Therefore, the opening 43 has two rectangular portions, that is, a rectangular large hole 43A that is slightly larger than the outer diameter of the two semiconductor switching elements 31, and two long sides of the large hole 43A. It consists of small rectangular small holes 43B provided by being recessed in the direction. The region facing the large hole portion 43A on the surface of the bus bar 42 is two drain side connection portions 44A corresponding to the drain terminal 33A of each semiconductor switching element 31, and the region facing the two small hole portions 43B is The two source side connection portions 44B corresponding to the source terminal 33B of each semiconductor switching element 31 are provided.

Of these connection portions 44A and 44B, groove portions 45 are provided at three locations on the outer edge of the drain side connection portion 44A. Of these groove portions 45, one groove portion 45A is provided between the two drain side connection portions 44A, that is, along the side on the drain side connection portion 44A side adjacent to each drain side connection portion 44A. It is shared by both drain side connection portions 44A. Further, the remaining two groove portions 45B are provided along the sides facing the sides along the central groove portion 45A in each drain side connection portion 44A.
On the other hand, the gate terminal 33 </ b> C is connected to a land portion 46 provided on the control circuit board 41 by soldering.

  Thus, also in this embodiment, since the groove part 45 is provided along the outer edge of the drain side connection part 44A, there exists an effect similar to 1st Embodiment. Further, since the groove 45A is provided between the two drain side connection portions 44A, even if a plurality of semiconductor switching elements 31 are arranged in parallel in the same opening 43, the semiconductor switching elements 31 are adjacent to each other. It is possible to avoid adverse effects due to the positional shift toward the element 31 side. Further, since the central groove 45A is shared by both drain side connection portions 44A, the structure can be simplified and the manufacturing efficiency can be improved.

<Other embodiments>
The technical scope of the present invention is not limited by the above-described embodiments, and, for example, those described below are also included in the technical scope of the present invention. In addition, the technical scope of the present invention extends to an equivalent range.

(1) In each of the above embodiments, the grooves 28 and 45 are provided in the drain side connection portions 27A and 44A corresponding to the drain terminal of the semiconductor switching element 31, but the source side connection portions 27B and 44B are provided with recesses. May be. Further, the concave portion of the present invention can be applied even when other electronic components are mounted by soldering.

(2) In the first embodiment, the groove portion 28 is provided by scraping the plating layer 22B on the surface of the bus bar substrate 22 with a laser. For example, as shown in FIG. The plating layer 22B on the surface and a part of the base material 22C below the plating layer 22B may be provided by cutting with a laser or the like.

(3) In the first embodiment, the groove portion 28 is formed by laser, but the concave portion may be formed by scraping the plating layer by, for example, a well-known sand blasting method or etching method.

(4) In each of the above embodiments, the plating layer 22B is a plating layer containing tin. However, there is no particular limitation on the components of the plating layer, as long as it is normally used for plating a bus bar. I do not care. Moreover, the plating layer may be a stack of a plurality of layers containing different components. In this case, in order to form the recess, all of the plurality of layers forming the plating layer may be removed, or only a part of the surface side layer may be removed.

(5) In the above embodiment, the electronic component is mounted on the circuit structure 20 in which the bus bar board 22 and the control circuit board 21 are stacked. For example, the electronic component is not provided, and the bus bar board is mounted on the bus bar board. Those having only electronic components are also included in the present invention. Moreover, in the said embodiment, the bus-bar board | substrate with which the several bus-bar was formed in parallel was used, For example, what mounted the electrical component on only one bus-bar is also contained in this invention.

(6) In the above embodiment, the groove portions 28 and 45 are provided along the two opposite sides in the drain side connection portions 27A and 44A over the entire length of the sides, but the length of the recess is not particularly limited, It may be shorter than the length of each side corresponding to the solder adhesion region. Further, for example, a plurality of concave portions may be provided at intervals along one side of the solder adhesion region.

(7) In the first embodiment, in the drain side connection portion 27A, the groove portion 28 extends along the side corresponding to the side on which the source terminal 33B and the gate terminal 33C of the semiconductor switching element 31 protrude and the side facing this side. However, the position where the recess is provided is not particularly limited, and may be provided at a position where the solder flow is desired to be restricted. Specifically, for example, as shown in FIG. 8A, a groove 51 may be provided along two sides that intersect the two sides. Or as shown to FIG. 8B, the L-shaped groove part 52 may be provided along two sides which mutually cross | intersect. Alternatively, as shown in FIG. 8C, L-shaped grooves 53 may be provided at the four corners of the drain side connection portion 27A.

(8) In the above embodiment, the concave portion is formed on the bus bar substrate 22. However, the present invention is not limited to this. For example, the concave portion is formed on a conductive path (for example, a conductive path of a pressure film substrate) disposed on the substrate. It may be a thing.

The perspective view of the electrical junction box of a 1st embodiment Perspective view of circuit structure Partial enlarged top view of the circuit structure before mounting electronic components Partial enlarged top view of the circuit structure after mounting electronic components Side sectional view showing the manufacturing process of the circuit structure Partially enlarged top view of the circuit structure of the second embodiment Side sectional view which shows the manufacturing process of the circuit structure of other embodiment (2) Partial enlarged top view of the circuit structure of another embodiment (7)

Explanation of symbols

20, 40 ... circuit components 21, 41 ... control circuit boards 24, 42 ... bus bar 26 ... opening 27A ... drain side connection part (solder adhesion region)
28 ... Groove (recess)
31 ... Semiconductor switching element (electronic component)
33 ... Terminal

Claims (5)

In a circuit structure including a conductive path and an electronic component provided with a terminal and soldered to the conductive path,
The circuit structure according to claim 1, wherein the conductive path is provided with a recess around a solder adhesion region to which solder for soldering the terminal adheres. A circuit board having a conductive path formed on at least one surface side, an electronic component provided with a terminal and mounted on the one surface side of the circuit board, and a bus bar provided on the other surface side of the circuit board, The circuit board has a circuit structure in which an opening penetrating in the thickness direction is formed, and the terminal is soldered to an exposed surface of the bus bar facing the opening,
A circuit structure, wherein a concave portion is provided around a solder adhesion region to which solder for soldering the terminal adheres on the exposed surface.   The circuit structure according to claim 1, wherein the recess is formed only in a part of the periphery of the solder adhesion region.   4. The semiconductor device according to claim 1, wherein a plurality of solder adhesion regions are provided in parallel, and the concave portion is provided at a position facing an adjacent solder adhesion region at an outer edge of the solder adhesion region. A circuit structure according to the above.   The circuit structure according to claim 4, wherein the concave portion is shared by a plurality of the solder adhesion regions adjacent to each other.

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