Electronic circuit and manufacturing method of electronic circuit

Abstract

An electronic circuit disclosed herein comprises: a substrate having a surface on which an electronic component is mounted; a frame that is mounted on the surface of the substrate and has a top plate part that covers the surface of the substrate; and a flat cover that is attached to the upper side of the frame so as to cover the top plate part of the frame. The frame has, on the upper side of the electronic component, a flat coating part that is part of the top plate part and covers the electronic component, a plurality of wall parts formed around the coating part by bending a portion of the top plate part, a first resin filling region surrounded by the plurality of wall parts, and a resin injection hole provided in the coating part. One among the cover and the frame has a plurality of protrusions that protrude toward and come into contact with the other one among the cover and the frame, thereby forming second resin filling regions at constant intervals between the cover and the coating part of the frame.

Description

Electronic circuit and method for manufacturing the same

[0001] The present invention relates to electronic circuits and methods for manufacturing electronic circuits.

[0002] The following Patent Document 1 discloses a technology in which, in a circuit module, silicone grease is filled between the top surface of an electronic component mounted on a circuit board and the flat portion of a plate member through an opening formed in the flat portion, thereby enabling heat from the electronic component to be dissipated through the silicone grease and the plate member.

[0003] Japanese Patent Application Laid-Open No. 2018-32658

[0004] However, with the technology of Patent Document 1, the silicone grease that spills out from the opening in the flat surface of the plate member onto the flat surface protrudes in the vertical direction, and there is a risk that it may interfere with other components located above the circuit module when the circuit module is mounted on a product.

[0005] Furthermore, with the technology of Patent Document 1, there is a risk that the silicone grease applied onto the electronic components may leak out horizontally and adhere to and affect other electronic components on the circuit board.

[0006] An electronic circuit according to one embodiment comprises a substrate having electronic components mounted on its surface, a frame mounted on the surface of the substrate and having a top plate portion covering the surface of the substrate, and a flat cover attached to the upper side of the frame so as to cover the top plate portion of the frame, the frame having, above the electronic components, a flat covering portion which is part of the top plate portion and covers the electronic components, a plurality of wall portions formed around the covering portion by bending a portion of the top plate portion, a first resin filling area surrounded by the plurality of wall portions, and a resin injection hole provided in the covering portion, and one of the cover and the frame has a plurality of protrusions which protrude toward the other of the cover and the frame and abut against the other to form a second resin filling area having a fixed gap between the cover and the covering portion of the frame.

[0007] According to an electronic circuit of one embodiment, the heat dissipation effect of the heat dissipation resin on the electronic components can be improved, and protrusion of the heat dissipation resin in the vertical direction and leakage of the heat dissipation resin in the horizontal direction can be suppressed.

[0008] FIG. 1 is an external perspective view of an electronic circuit (with the cover attached) according to an embodiment; FIG. 2 is an external perspective view of an electronic circuit (with the cover removed) according to an embodiment; FIG. 3 is a diagram for explaining a method for processing a frame provided in an electronic circuit according to an embodiment; FIG. 4 is a diagram for explaining a method for injecting heat dissipation resin in an electronic circuit according to an embodiment; FIG. 5 is a diagram for explaining a method for processing a frame provided in an electronic circuit according to a first modified example of an embodiment; FIG. 6 is a diagram for explaining a method for injecting heat dissipation resin in an electronic circuit according to a first modified example of an embodiment;

[0009] An embodiment will be described below with reference to the drawings. For convenience, in the following description, the X-axis direction in the drawings will be referred to as the front-to-rear direction, the Y-axis direction in the drawings will be referred to as the left-to-right direction, and the Z-axis direction in the drawings will be referred to as the up-to-down direction. The positive X-axis direction will be referred to as the forward direction, the positive Y-axis direction will be referred to as the rightward direction, and the positive Z-axis direction will be referred to as the upward direction. These directions indicate relative positional relationships within the device and do not limit the installation direction or operation direction of the device. Any devices that have the same relative positional relationships within the device, even if they have different installation directions or operation directions, are all within the scope of the present invention.

[0010] (Configuration of Electronic Circuit 100) Fig. 1 is a perspective view of the exterior of an electronic circuit 100 (with a cover 140 attached) according to one embodiment. Fig. 2 is a perspective view of the exterior of an electronic circuit 100 (with the cover 140 removed) according to one embodiment.

[0011] 1 and 2 is a small-sized information processing device capable of implementing various functions (e.g., a calculation function, a wireless communication function, a storage function, etc.) For example, the electronic circuit 100 is mounted in another device (e.g., an on-board device mounted in a vehicle such as an automobile) to function as a control device in the other device.

[0012] The electronic circuit 100 is configured to be able to realize various functions by mounting one or more electronic components 120 (such as ICs) on a surface 110A of a flat, resin-made substrate 110. In the example shown in Fig. 2, one electronic component 120 having a rectangular shape when viewed from above (positive direction of the Z axis) is mounted in the center of the surface 110A of the substrate 110. The substrate 110 is a horizontal, flat, resin member having a rectangular shape when viewed from above (positive direction of the Z axis).

[0013] 1 and 2, the electronic circuit 100 includes a frame 130. The frame 130 is formed using a metal plate, is thin in the vertical direction (Z-axis direction), and is a rectangular parallelepiped member with an open bottom.

[0014] The frame 130 has a top plate portion 131 that is horizontally flat and rectangular when viewed from above (positive Z-axis direction), and four side wall portions 132 that are vertical walls and hang down from each of the four sides of the top plate portion 131.

[0015] The frame 130 is fixed to the surface 110A of the substrate 110 by soldering the lower edge of each of the four side wall portions 132 to the surface 110A of the substrate 110.

[0016] Each of the four side wall portions 132 has a plurality of engagement holes 132A arranged in a direction extending in the side wall portion 132 (X-axis direction or Y-axis direction).

[0017] As shown in FIGS. 1 and 2, the electronic circuit 100 also includes a metal, flat cover 140 attached to the upper side (positive side of the Z axis) of the frame 130 so as to cover the top panel portion 131 of the frame 130.

[0018] The cover 140 has a rectangular base 141 that is slightly larger than the top plate 131 of the frame 130 when viewed from above (positive direction of the Z axis). The cover 140 also has a plurality of engagement claws 142 arranged on each of the four sides of the base 141 in the direction in which the side extends (X axis direction or Y axis direction).

[0019] Before bending, each of the engaging claws 142 is provided on the same plane as the base 141, and is bent downward (in the negative direction of the Z axis) at a right angle at the connection portion with the base 141 (i.e., the four sides of the base 141) by the bending process, thereby becoming vertical. Each of the engaging claws 142 has an engaging protrusion 142A protruding from the back surface.

[0020] 1 , when the cover 140 is attached to the frame 130, each of the multiple engagement claws 142 overlaps with the surface of the side wall portion 132 of the frame 130. Then, the engagement protrusion 142A of each of the multiple engagement claws 142 is fitted into each of the multiple engagement holes 132A provided at corresponding positions on the side wall portion 132. In this way, the cover 140 is fixed to the frame 130.

[0021] 2, the frame 130 has a flat covering portion 131B that covers the electronic component 120 in the center of the top plate portion 131, which is above the electronic component 120. The covering portion 131B has a rectangular shape that is approximately the same size as the electronic component 120 when viewed in a plan view from above (positive direction of the Z axis).

[0022] 2, the frame 130 has four openings 131A formed around the covering portion 131B of the top plate portion 131. As shown in FIG. 1, a cover 140 that covers the entire top plate portion 131 is attached to the frame 130, thereby closing the multiple openings 131A.

[0023] 2, frame 130 has a plurality of vertical wall portions 131D facing opening 131A on the outer periphery (i.e., four sides) of covering portion 131B of top plate portion 131. Wall portions 131D form a first resin filling region 161 surrounded by the plurality of wall portions 131D between covering portion 131B and the top surface of electronic component 120. Note that, as shown in FIG. 2, a resin injection hole 131C for injecting heat dissipation resin 150 into first resin filling region 161 is formed in the center of covering portion 131B.

[0024] 2, the frame 130 has four beams 131E connected to the outer periphery (i.e., four sides) of the covering portion 131B around the covering portion 131B of the top plate portion 131. The covering portion 131B is supported from four directions by the four beams 131E.

[0025] (Method of Processing Frame 130) FIG. 3 is a diagram for explaining a method of processing the frame 130 provided in the electronic circuit 100 according to one embodiment.

[0026] As shown in FIG. 3( a), in the “frame forming process,” a single metal plate is processed (punched, etc.) to form frame 130 having covering portion 131B, resin injection hole 131C, four openings 131A, four side wall portions 132, multiple wall portions 131D, and four beam portions 131E, all of which are on the same plane.

[0027] Then, as shown in Figure 3(b), in the "frame forming process", each of the four side wall portions 132 of the frame 130 is bent downward (in the negative direction of the Z axis) at a right angle at the connection portion with the top plate portion 131 (i.e., the four sides of the top plate portion 131), as shown by the dotted lines in the figure, thereby becoming vertical.

[0028] Also, as shown in Figure 3(b), in the "frame forming process", each of the multiple wall portions 131D of the frame 130 is bent downward (in the negative direction of the Z axis) at a right angle at the connection portion with the covering portion 131B (i.e., the outer peripheral edge portion of the covering portion 131B), as shown by the dotted line in the figure, thereby becoming vertical.

[0029] As a result, as shown in FIG. 3B, a rectangular first resin filling region 161 surrounded by a plurality of wall portions 131D is formed on the lower side (negative side of the Z axis) of the covering portion 131B.

[0030] 3A, each of the four beams 131E of the frame 130 has a rectangular second wall 134 in a portion that contacts the outer periphery of the covering portion 131B. As shown in FIG. 3B, each of the four second walls 134 of the frame 130 is bent downward (in the negative direction of the Z axis) at a right angle at the connection portion with the covering portion 131B (i.e., the outer periphery of the covering portion 131B) by bending, thereby becoming vertical. At this time, a rectangular opening of the same shape as the second wall 134 is formed in each of the four beams 131E at the location where the second wall 134 existed before bending.

[0031] As a result, as shown in FIG. 3B, the first resin filling region 161 on the lower side (negative side of the Z axis) of the covering portion 131B is further surrounded by four second wall portions 134.

[0032] (Method of Injecting Heat Dissipating Resin 150) Figure 4 is a diagram illustrating a method of injecting heat dissipating resin 150 into electronic circuit 100 according to one embodiment. Figure 4(a) is a plan view and a side cross-sectional view showing electronic circuit 100 in a state in which heat dissipating resin 150 has been injected into first resin filling region 161. Figure 4(b) is a plan view and a side cross-sectional view showing electronic circuit 100 in a state in which cover 140 has been attached after heat dissipating resin 150 has been injected into first resin filling region 161.

[0033] In the manufacturing method of electronic circuit 100 according to one embodiment, electronic components 120 are mounted on front surface 110A of substrate 110 in an "electronic component mounting process." For example, in the "electronic component mounting process," substrate 110 with electronic components 120 mounted thereon is placed in a reflow furnace and heated, thereby soldering electronic components 120 to front surface 110A of substrate 110.

[0034] Furthermore, in a "frame mounting process" following the "electronic component mounting process," the frame 130 is mounted on the surface 110A of the substrate 110. For example, in the "frame mounting process," the substrate 110 with the frame 130 placed thereon is placed in a reflow furnace and heated, thereby soldering the lower edge of each of the four side wall portions 132 of the frame 130 to the surface 110A of the substrate 110. As a result, as shown in FIG. 4( a), the rectangular electronic component 120 mounted on the surface 110A of the substrate 110 is covered by the rectangular covering portion 131B of the frame 130.

[0035] Furthermore, in a "resin injection process" following the "frame mounting process," heat dissipation resin 150 is injected into first resin filling region 161 from resin injection hole 131C of frame 130 until heat dissipation resin 150 overflows onto covering portion 131B of frame 130. As a result, electronic circuit 100 reaches a state in which first resin filling region 161 is filled with heat dissipation resin 150 and heat dissipation resin 150 has overflowed onto covering portion 131B, as shown in FIG.

[0036] The heat dissipation resin 150 may be a thermally conductive material such as silicone grease, which is a resin containing filler.

[0037] Thereafter, in a "cover attachment step" as shown in FIG. 4( b), the cover 140 is attached to the frame 130. At this time, as shown in FIG. 4( b), a plurality of protrusions 143 protruding downward from the underside of the base 141 of the cover 140 come into contact with the top plate 131 of the frame 130, thereby forming a gap with a fixed interval between the base 141 of the cover 140 and the top plate 131 of the frame 130, and forming a second resin filling region 162 with a fixed interval between the base 141 of the cover 140 and the covering portion 131B of the frame 130. At this time, the heat dissipation resin 150 spilling onto the covering portion 131B is crushed from above and below by the base 141 of the cover 140 and the covering portion 131B of the frame 130, and is thereby spread horizontally within the second resin filling region 162.

[0038] As described above, in electronic circuit 100 according to one embodiment, first resin filling region 161 is formed between electronic component 120 and covering portion 131B of frame 130. As a result, in electronic circuit 100 according to one embodiment, by filling first resin filling region 161 with heat dissipation resin 150, heat from electronic component 120 can be transferred to frame 130 via heat dissipation resin 150 filled in first resin filling region 161, and dissipated from frame 130.

[0039] Furthermore, in the electronic circuit 100 according to one embodiment, the resin injection hole 131C is provided in the covering portion 131B, so that the heat dissipation resin 150 can be easily injected into the first resin filling area 161 through the resin injection hole 131C.

[0040] Furthermore, in electronic circuit 100 according to one embodiment, cover 140 is attached to the upper side of frame 130. As a result, in electronic circuit 100 according to one embodiment, heat dissipation resin 150 that has spilled onto covering portion 131B can be flattened by cover 140, and therefore protrusion of heat dissipation resin 150 in the height direction can be suppressed by cover 140. Therefore, in a product in which electronic circuit 100 is mounted, heat dissipation resin 150 can be suppressed from interfering with other components present above electronic circuit 100.

[0041] Furthermore, in the electronic circuit 100 according to an embodiment, the cover 140 has a plurality of protrusions 143, which allows a second resin filling region 162 having a fixed gap to be formed between the base 141 of the cover 140 and the covering portion 131B of the frame 130. As a result, in the electronic circuit 100 according to an embodiment, when the cover 140 is attached to the frame 130, the heat dissipation resin 150 that has spilled onto the covering portion 131B can be horizontally spread within the second resin filling region 162 to form a flat surface, i.e., the heat dissipation resin 150 can be filled into the second resin filling region 162. Therefore, in the electronic circuit 100 according to an embodiment, heat from the electronic component 120 can be transferred to the frame 130 via the heat dissipation resin 150 filled in the first resin filling region 161 and dissipated from the frame 130, and further transferred to the cover 140 via the heat dissipation resin 150 filled in the second resin filling region 162 and dissipated from the cover 140.

[0042] Furthermore, in the electronic circuit 100 according to one embodiment, the frame 130 has a plurality of wall portions 131D that surround the first resin filling region 161. This makes it possible for the electronic circuit 100 according to one embodiment to prevent the heat dissipation resin 150 injected into the first resin filling region 161 from spilling out beyond the first resin filling region 161 (i.e., leaking in the horizontal direction), thereby preventing the heat dissipation resin 150 from adhering to other electronic components 120, etc.

[0043] 4 , in electronic circuit 100 according to one embodiment, each of multiple wall portions 131D is provided outside the outer periphery of electronic component 120, and therefore each of multiple wall portions 131D can extend below the top surface of electronic component 120. This makes it possible for electronic circuit 100 according to one embodiment to further prevent heat dissipation resin 150 injected into first resin filling region 161 from spilling out outside first resin filling region 161, and therefore to further prevent heat dissipation resin 150 from adhering to other electronic components 120, etc.

[0044] Furthermore, in the electronic circuit 100 according to one embodiment, the frame 130 has a plurality of second wall portions 134 that surround the first resin filling region 161. This makes it possible for the electronic circuit 100 according to one embodiment to further prevent the heat dissipation resin 150 injected into the first resin filling region 161 from spilling out beyond the first resin filling region 161, and therefore to further prevent the heat dissipation resin 150 from adhering to other electronic components 120, etc.

[0045] Furthermore, in the electronic circuit 100 according to one embodiment, the cover 140 has a plurality of engagement claws 142 arranged along the outer periphery of the cover 140, and each of the plurality of engagement claws 142 engages with a side wall 132 of the frame 130, thereby securing the cover 140 to the frame 130. This allows the electronic circuit 100 according to one embodiment to easily and reliably secure the cover 140 at a predetermined height so that a constant gap is formed between the cover 140 and the frame 130.

[0046] Moreover, a manufacturing method of electronic circuit 100 according to one embodiment includes an electronic component mounting step of mounting electronic component 120 on surface 110A of substrate 110; a frame forming step of forming, in frame 130, flat covering portion 131B that is part of top plate portion 131 and covers electronic component 120, a plurality of wall portions 131D formed around covering portion 131B by bending a portion of top plate portion 131, a first resin filling region 161 surrounded by the plurality of wall portions 131D, and a resin injection hole 131C provided in covering portion 131B; and a frame mounting step of mounting frame 130 on surface 110A of substrate 110. The method includes a resin injection process in which heat dissipation resin 150 is injected from resin injection hole 131C into first resin filling area 161 until the heat dissipation resin overflows onto covering portion 131B, and a cover attachment process in which cover 140 is attached to the upper side of frame 130. In the cover attachment process, multiple protrusions 143 on cover 140 abut against top plate portion 131 of frame 130, thereby forming second resin filling area 162 having a certain gap between cover 140 and covering portion 131B of frame 130, and the heat dissipation resin 150 overflowing onto covering portion 131B is pushed out within second resin filling area 162.

[0047] As a result, in one embodiment of the manufacturing method for the electronic circuit 100, the heat dissipation resin 150 that has spilled onto the covering portion 131B can be crushed with the cover 140 to make it flat, and therefore the height position of the heat dissipation resin 150 can be regulated by the cover 140, thereby preventing the heat dissipation resin 150 from coming into contact with components on the electronic circuit 100 in a product in which the electronic circuit 100 is implemented.

[0048] Furthermore, as a result, the manufacturing method of the electronic circuit 100 according to one embodiment can transfer the heat of the electronic component 120 to the frame 130 via the heat dissipation resin 150 filled in the first resin filling area 161 and dissipate the heat from the frame 130, and further transfer the heat to the cover 140 via the heat dissipation resin 150 filled in the second resin filling area 162 and dissipate the heat from the cover 140.

[0049] [First Modification] (Method of Processing Frame 130-2) FIG. 5 is a diagram for explaining a method of processing the frame 130-2 included in the electronic circuit 100-2 according to a first modification of the embodiment.

[0050] As shown in FIG. 5A, the frame 130-2 differs from the frame 130 of the electronic circuit 100 shown in FIG. 3 in that the covering portion 131B has an octagonal shape when viewed from above (positive Z-axis direction) in a plan view.

[0051] 5A, the frame 130-2 differs from the frame 130 shown in FIG. 3 in that it has four wall portions 131D facing the opening 131A at the outer periphery of the covering portion 131B of the top plate portion 131. Each of the four wall portions 131D is provided on one of four oblique sides of the eight sides at the outer periphery of the covering portion 131B. The four wall portions 131D form a first resin filling region 161 surrounded by the four wall portions 131D between the covering portion 131B and the top surface of the electronic component 120.

[0052] As shown in FIG. 5(a), in the "frame forming process," a single metal plate is processed (punched, etc.) to form frame 130-2 having a covering portion 131B, a resin injection hole 131C, four openings 131A, four side wall portions 132, four wall portions 131D, and four beam portions 131E, all of which are on the same plane.

[0053] Then, as shown in Figure 5(b), in the "frame forming process", each of the four side wall portions 132 of the frame 130-2 is bent downward (in the negative direction of the Z axis) at a right angle at the connection portion with the top plate portion 131 (i.e., the four sides of the top plate portion 131), as shown by the dotted lines in the figure, thereby becoming vertical.

[0054] Also, as shown in Figure 5(b), in the "frame forming process", each of the four wall portions 131D of the frame 130-2 is bent downward (in the negative direction of the Z axis) at a right angle at the connection portion with the covering portion 131B (i.e., the outer peripheral edge portion of the covering portion 131B), as shown by the dotted lines in the figure, thereby becoming vertical.

[0055] As a result, as shown in FIG. 5B, an octagonal first resin filling region 161 surrounded by four wall portions 131D is formed on the lower side (negative side of the Z axis) of the covering portion 131B.

[0056] 5A, each of the four beams 131E of the frame 130-2 has a rectangular second wall 134 in a portion that contacts the outer periphery of the covering portion 131B. As shown in FIG. 5B, each of the four second walls 134 of the frame 130-2 is bent downward (in the negative direction of the Z axis) at a right angle at the connection portion with the covering portion 131B (i.e., the outer periphery of the covering portion 131B) through the bending process, thereby becoming vertical. At this time, a rectangular opening of the same shape as the second wall 134 is formed in each of the four beams 131E at the location where the second wall 134 existed before bending.

[0057] As a result, as shown in FIG. 5B, the octagonal first resin filling region 161 on the lower side (negative side of the Z axis) of the covering portion 131B is further surrounded by four second wall portions 134.

[0058] (Method of Injecting Heat Dissipating Resin 150) Figure 6 is a diagram for explaining a method of injecting heat dissipating resin 150 into an electronic circuit 100-2 according to a first modified example of an embodiment. Figure 6(a) is a plan view and a side cross-sectional view showing the electronic circuit 100-2 in a state in which the heat dissipating resin 150 has been injected into the first resin filling region 161. Figure 6(b) is a plan view and a side cross-sectional view showing the electronic circuit 100-2 in a state in which the cover 140 has been attached after the heat dissipating resin 150 has been injected into the first resin filling region 161.

[0059] In the manufacturing method of the electronic circuit 100-2 according to the first modified example of the embodiment, in an "electronic component mounting step," the electronic component 120 is mounted on the front surface 110A of the substrate 110. For example, in the "electronic component mounting step," the substrate 110 on which the electronic component 120 is mounted is placed in a reflow furnace and heated, thereby soldering the electronic component 120 to the front surface 110A of the substrate 110.

[0060] Furthermore, in a "frame mounting process" following the "electronic component mounting process," the frame 130 is mounted on the surface 110A of the substrate 110. For example, in the "frame mounting process," the substrate 110 with the frame 130 placed thereon is placed in a reflow furnace and heated, thereby soldering the lower edge of each of the four side wall portions 132 of the frame 130 to the surface 110A of the substrate 110. As a result, as shown in FIG. 6( a), the rectangular electronic component 120 mounted on the surface 110A of the substrate 110 is partially covered by the octagonal covering portion 131B of the frame 130.

[0061] Furthermore, in a "resin injection process" following the "frame mounting process," heat dissipation resin 150 is injected into first resin filling region 161 from resin injection hole 131C of frame 130 until heat dissipation resin 150 overflows onto covering portion 131B of frame 130. As a result, electronic circuit 100-2 reaches a state where first resin filling region 161 is filled with heat dissipation resin 150 and heat dissipation resin 150 overflows onto covering portion 131B, as shown in FIG.

[0062] Thereafter, in a "cover attachment step" as shown in Fig. 6(b) , the cover 140 is attached to the frame 130. At this time, as shown in Fig. 6(b) , a plurality of protrusions 143 protruding downward from the underside of the base 141 of the cover 140 come into contact with the top plate 131 of the frame 130, thereby forming a gap with a fixed interval between the base 141 of the cover 140 and the top plate 131 of the frame 130, and forming a second resin filling region 162 with a fixed interval between the base 141 of the cover 140 and the covering portion 131B of the frame 130. At this time, the heat dissipation resin 150 spilling onto the covering portion 131B is crushed from above and below by the base 141 of the cover 140 and the covering portion 131B of the frame 130, and is thereby spread horizontally within the second resin filling region 162.

[0063] Like electronic circuit 100, electronic circuit 100-2 has a first resin filling area 161 surrounded by multiple wall portions 131D and multiple second wall portions 134, and a second resin filling area 162 on the upper side of electronic component 120, and therefore can achieve the same effects as electronic circuit 100.

[0064] Second Modification (Method of Processing Frame 130-3) FIG. 7 is a diagram for explaining a method of processing the frame 130-3 included in the electronic circuit 100-3 according to a second modification of the embodiment.

[0065] As shown in Figure 7(a), frame 130-3 differs from frame 130 provided in electronic circuit 100 shown in Figure 3 in that electronic component 120 is provided in a portion other than the center on surface 110A of substrate 110, and covering portion 131B is provided in a portion other than the center on top plate portion 131.

[0066] Also, as shown in Figure 7(a), frame 130-3 differs from frame 130 provided in electronic circuit 100 shown in Figure 3 in that covering portion 131B has an octagonal shape when viewed in a plan view from above (positive Z-axis direction).

[0067] Also, as shown in FIG. 7(a), frame 130-3 differs from frame 130 provided in electronic circuit 100 shown in FIG. 3 in that covering portion 131B is supported at its left and right edges by two beam portions 131E extending in the left-right direction (Y-axis direction).

[0068] 7A, the frame 130-3 differs from the frame 130 shown in FIG. 3 in that it has two walls 131D, one on the front side (positive side of the X-axis) and the other on the rear side (negative side of the X-axis) of the covering portion 131B. The two walls 131D form a first resin filling region 161 surrounded by the two walls 131D between the covering portion 131B and the top surface of the electronic component 120.

[0069] As shown in FIG. 7(a), in the "frame forming process," a single metal plate is processed (punched, etc.) to form frame 130-3 having a covering portion 131B, a resin injection hole 131C, two openings 131A, four side wall portions 132, two wall portions 131D, and two beam portions 131E, all of which are on the same plane.

[0070] Then, as shown in Figure 7(b), in the "frame forming process", each of the four side wall portions 132 of the frame 130-3 is bent downward (in the negative direction of the Z axis) at a right angle at the connection portion with the top plate portion 131 (i.e., the four sides of the top plate portion 131), as shown by the dotted lines in the figure, thereby becoming vertical.

[0071] Also, as shown in Figure 7(b), in the "frame forming process", each of the two wall portions 131D of the frame 130-3 is bent downward (in the negative direction of the Z axis) at a right angle at the connection portion with the covering portion 131B (i.e., the outer peripheral edge portion of the covering portion 131B), as shown by the dotted line in the figure, by a bending process, thereby becoming vertical.

[0072] As a result, as shown in FIG. 7B, an octagonal first resin filling region 161 surrounded by two wall portions 131D is formed on the lower side (negative side of the Z axis) of the covering portion 131B.

[0073] 7(a), each of the two beam portions 131E of the frame 130-3 has a rectangular second wall portion 134 in a portion that contacts the outer periphery of the covering portion 131B. Then, as shown in FIG. 7(b), each of the two second wall portions 134 of the frame 130-3 is bent downward (in the negative direction of the Z axis) at a right angle at the connection portion with the covering portion 131B (i.e., the outer periphery of the covering portion 131B) by bending, thereby becoming vertical.

[0074] As a result, as shown in FIG. 7B, the octagonal first resin filling region 161 on the lower side (negative side of the Z axis) of the covering portion 131B is further surrounded by the two second wall portions 134.

[0075] (Method of Injecting Heat Dissipating Resin 150) Figure 8 is a diagram for explaining a method of injecting heat dissipating resin 150 into an electronic circuit 100-3 according to a second modified example of an embodiment. Figure 8(a) is a plan view and a side cross-sectional view showing the electronic circuit 100-3 in a state in which the heat dissipating resin 150 has been injected into the first resin filling region 161. Figure 8(b) is a plan view and a side cross-sectional view showing the electronic circuit 100-3 in a state in which the cover 140 has been attached after the heat dissipating resin 150 has been injected into the first resin filling region 161.

[0076] In the manufacturing method of the electronic circuit 100-3 according to the second modified example of the embodiment, in an "electronic component mounting step," the electronic component 120 is mounted on the front surface 110A of the substrate 110. For example, in the "electronic component mounting step," the substrate 110 on which the electronic component 120 is mounted is placed in a reflow furnace and heated, thereby soldering the electronic component 120 to the front surface 110A of the substrate 110.

[0077] Furthermore, in a "frame mounting process" following the "electronic component mounting process," the frame 130 is mounted on the surface 110A of the substrate 110. For example, in the "frame mounting process," the substrate 110 with the frame 130 placed thereon is placed in a reflow furnace and heated, thereby soldering the lower edge of each of the four side wall portions 132 of the frame 130 to the surface 110A of the substrate 110. As a result, as shown in FIG. 8( a), the rectangular electronic component 120 mounted on the surface 110A of the substrate 110 is partially covered by the octagonal covering portion 131B of the frame 130.

[0078] Furthermore, in a "resin injection process" following the "frame mounting process," heat dissipation resin 150 is injected into first resin filling region 161 from resin injection hole 131C of frame 130 until heat dissipation resin 150 overflows onto covering portion 131B of frame 130. As a result, electronic circuit 100-3 reaches a state in which first resin filling region 161 is filled with heat dissipation resin 150 and heat dissipation resin 150 overflows onto covering portion 131B, as shown in FIG.

[0079] Thereafter, in a "cover attachment step" as shown in FIG. 8( b), the cover 140 is attached to the frame 130. At this time, as shown in FIG. 8( b), a plurality of protrusions 143 protruding downward from the underside of the base 141 of the cover 140 come into contact with the top plate 131 of the frame 130, thereby forming a gap with a fixed interval between the base 141 of the cover 140 and the top plate 131 of the frame 130, and forming a second resin filling region 162 with a fixed interval between the base 141 of the cover 140 and the covering portion 131B of the frame 130. At this time, the heat dissipation resin 150 spilling onto the covering portion 131B is crushed from above and below by the base 141 of the cover 140 and the covering portion 131B of the frame 130, and is thereby spread horizontally within the second resin filling region 162.

[0080] Like electronic circuit 100, electronic circuit 100-3 has a first resin filling area 161 surrounded by multiple wall portions 131D and multiple second wall portions 134, and a second resin filling area 162 on the upper side of electronic component 120, and therefore can achieve the same effects as electronic circuit 100.

[0081] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

[0082] For example, instead of providing multiple protrusions 143 on the base 141 of the cover 140, multiple protrusions may be provided on the top plate portion 131 of the frame 130, and the multiple protrusions may be abutted against the base 141 of the cover 140, thereby forming a gap of a certain distance between the base 141 of the cover 140 and the top plate portion 131 of the frame 130.

[0083] Furthermore, for example, in each of the above manufacturing methods, a "second resin injection step" of applying heat dissipation resin 150 onto covering portion 131B may be provided before the "cover attachment step." In this case, in the "cover attachment step," multiple protrusions 143 may come into contact with top plate portion 131 of frame 130 to form second resin filling region 162 having a certain gap between cover 140 and covering portion 131B of frame 130, and heat dissipation resin 150 applied in the "second resin injection step" may be pushed and spread within second resin filling region 162.

[0084] This international application claims priority based on Japanese Patent Application No. 2024-097348, filed on June 17, 2024, the entire contents of which are incorporated herein by reference.

[0085] 100, 100-2, 100-3 Electronic circuit 110 Substrate 110A Surface 120 Electronic component 130, 130-2, 130-3 Frame 131 Top plate portion 131A Opening 131B Covering portion 131C Resin injection hole 131D Wall portion 131E Beam portion 132 Side wall portion 132A Engagement hole 134 Second wall portion 140 Cover 141 Base portion 142 Engagement claw 142A Engagement protrusion 143 Protrusion 150 Heat dissipation resin 161 First resin filling area 162 Second resin filling area

Claims

1. An electronic circuit comprising: a substrate on whose surface electronic components are mounted; a frame mounted on the surface of the substrate and having a top plate portion covering the surface of the substrate; and a flat cover attached to the upper side of the frame so as to cover the top plate portion of the frame, wherein the frame has, above the electronic components, a flat covering portion which is part of the top plate portion and covers the electronic components, a plurality of wall portions formed around the covering portion by bending a portion of the top plate portion, a first resin filling area surrounded by the plurality of wall portions, and a resin injection hole provided in the covering portion, wherein one of the cover and the frame has a plurality of protrusions which protrude toward the other of the cover and the frame and abut against the other to form a second resin filling area with a fixed gap between the cover and the covering portion of the frame.

2. The electronic circuit according to claim 1, characterized in that the frame has a beam portion that is part of the top plate portion and supports the covering portion, the beam portion has a second wall portion that is formed around the covering portion by bending a part of the beam portion, and the first resin filling area is surrounded by the multiple wall portions and the second wall portion.

3. The electronic circuit according to claim 1, characterized in that the cover has a plurality of engaging claws arranged along the outer periphery of the cover, and each of the plurality of engaging claws engages with a side wall of the frame, thereby fixing the cover to the frame.

4. A method for manufacturing an electronic component comprising: a substrate on whose surface an electronic component is mounted; a frame having a top plate portion mounted on the surface of the substrate and covering the surface of the substrate; and a flat cover attached to the upper side of the frame so as to cover the top plate portion of the frame, the method comprising: an electronic component mounting step of mounting the electronic component on the surface of the substrate; a frame forming step of forming on the frame a flat covering portion that is part of the top plate portion and covers the electronic component, a plurality of wall portions formed around the covering portion by bending a portion of the top plate portion, a first resin filling area surrounded by the plurality of wall portions, and a resin injection hole provided in the covering portion; a frame mounting step of mounting the frame on the surface of the substrate; a resin injection step of injecting heat dissipating resin from the resin injection hole into the first resin filling area; and a cover mounting step of attaching the cover to the upper side of the frame, wherein in the cover mounting step: a plurality of protrusions on one of the cover and the frame abut against the other of the cover and the frame, thereby forming a second resin filling area having a fixed gap between the cover and the covering portion of the frame, and the heat dissipation resin that has overflowed onto the covering portion is pushed out within the second resin filling area.

5. A method for manufacturing an electronic component comprising: a substrate on whose surface an electronic component is mounted; a frame having a top plate portion mounted on the surface of the substrate and covering the surface of the substrate; and a flat cover attached to the upper side of the frame so as to cover the top plate portion of the frame, the method comprising: an electronic component mounting step of mounting the electronic component on the surface of the substrate; a frame forming step of forming on the frame a flat covering portion that is part of the top plate portion and covers the electronic component, a plurality of wall portions formed around the covering portion by bending a portion of the top plate portion, a first resin filling area surrounded by the plurality of wall portions, and a resin injection hole provided in the covering portion; a frame mounting step of mounting the frame on the surface of the substrate; a first resin injection step of injecting heat dissipating resin from the resin injection hole into the first resin filling area; a second resin injection step of applying heat dissipating resin onto the covering portion; and a cover attachment step of attaching the cover to the upper side of the frame, wherein in the cover attachment step: a plurality of protrusions on one of the cover and the frame abut against the other of the cover and the frame, thereby forming a second resin filling area having a fixed gap between the cover and the covering portion of the frame, and the heat dissipation resin applied in the second resin injection process is pushed and spread within the second resin filling area.

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