Electronic device

Abstract

To reduce a poor connection of an electronic device.SOLUTION: An electronic device 1 includes: an electronic component 2; and a circuit board 3. The electronic component 2 includes one or a plurality of heat radiation pads 22 on a component mounting surface 2a. The circuit board 3 includes: one or a plurality of heat dissipation lands 32; and an over-resist 34. The one or the plurality of heat dissipation lands 32 protrude from a substrate mounting surface 3a and receive a heat from the one or the plurality of heat dissipation pads 22. The over-resist 34 is a solder resist 33 disposed on a surface of the one or the plurality of heat dissipation lands 32 so as to cover the surface of the one or the plurality of heat dissipation lands 32 in at least a part of an outer circumference of the one or the plurality of heat dissipation lands 32 and so that a resist opening part is formed on the surface of the one or the plurality of heat dissipation lands 32.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an electronic device comprising an electronic component and a circuit board. [Background technology]

[0002] Patent Document 1 describes a method of soldering a circuit board having a plurality of connection terminals formed on its surface to an electronic component having a plurality of connection terminals formed on its back surface, with the connection terminals of the circuit board facing the connection terminals of the electronic component. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-334062 Summary of the Invention [Problem to be solved by the invention]

[0004] As a result of detailed investigations by the inventors, it was found that when mounting an electronic component on a circuit board, if the electronic component is tilted relative to the circuit board, the solder (i.e., solder fillet) applied to the connection point for mounting the electronic component on the circuit board will bulge, causing a poor connection, thereby reducing the reliability of the connection in the electronic device.

[0005] The present disclosure aims to reduce connection failures in electronic devices. [Means for solving the problem]

[0006] One aspect of the present disclosure is an electronic device (1) including an electronic component (2) and a circuit board (3). The electronic component has one or more heat dissipation pads (22) on a component mounting surface (2a) that faces the circuit board when the electronic component is mounted on the circuit board, for dissipating heat generated inside the electronic component.

[0007] The circuit board includes one or more heat dissipation lands (32) and an over resist (34). The one or more heat dissipation lands are formed to protrude from the board mounting surface (3a) that faces the electronic component when the electronic component is mounted on the circuit board, and receive heat from the one or more heat dissipation pads, respectively.

[0008] The over resist is a solder resist (33) placed on the surface of one or more heat dissipation lands so as to cover the surface of one or more heat dissipation lands at least in part around the periphery of the one or more heat dissipation lands and to form resist openings on the surface of the one or more heat dissipation lands.

[0009] In the electronic device of the present disclosure configured as described above, the over resist is installed so as to protrude from the surface of the heat dissipation land. Therefore, in the electronic device of the present disclosure, the over resist can restrict the placement of electronic components so that the board mounting surface and the component mounting surface do not come close to each other when the electronic components are mounted on the circuit board. This prevents the electronic components from tilting relative to the circuit board when mounted on the circuit board, thereby preventing the solder fillets from becoming bulged and reducing connection defects in the electronic device. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing a configuration of an electronic device according to a first embodiment. [Figure 2] FIG. [Figure 3] FIG. 2 is a plan view of the circuit board according to the first embodiment. [Figure 4] FIG. 10 is a cross-sectional view of an electronic device in which the solder fillet has a bulged shape. [Figure 5] FIG. 10 is a plan view of a circuit board according to a second embodiment. [Figure 6] FIG. 10 is a cross-sectional view showing the configuration of an electronic device according to a second embodiment. [Figure 7]FIG. 10 is a plan view of a circuit board according to a third embodiment. [Figure 8] FIG. 10 is a plan view of a circuit board according to a fourth embodiment. [Figure 9] FIG. 10 is a plan view of a circuit board according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] [First embodiment] A first embodiment of the present disclosure will be described below with reference to the drawings. 1, an electronic device 1 of this embodiment includes an electronic component 2 and a circuit board 3. The electronic device 1 is configured by accommodating the electronic component 2 and the circuit board 3 in a housing (not shown).

[0012] 2, the electronic component 2 of this embodiment is, for example, a power module IC, and is formed to have a QFN structure in which a plurality of electrode pads 21 are provided along the periphery of a mounting surface 2a (hereinafter referred to as component mounting surface 2a) on which the electronic component 2 is mounted on a circuit board 3. QFN is an abbreviation for Quad Flat Non-leaded package.

[0013] On the component mounting surface 2a, one or more heat dissipation pads 22 for dissipating heat generated inside the electronic component 2 are installed inside a plurality of electrode pads 21 arranged along the outer periphery of the component mounting surface 2a.

[0014] As shown in FIG. 1, the circuit board 3 is a wiring board (for example, a printed circuit board) in which various wiring patterns are formed on an insulating base material 30. On a mounting surface 3a (hereinafter referred to as board mounting surface 3a) on which electronic components 2 are mounted, circuit board 3 has provided thereon a plurality of lands 31 that form part of the wiring and one or more heat dissipation lands 32 that receive heat from heat dissipation pads 22 of electronic components 2. Lands 31 and heat dissipation lands 32 are formed so as to protrude from board mounting surface 3a.

[0015] The lands 31 are arranged so as to face the electrode pads 21 of the electronic component 2, respectively. The heat dissipation lands 32 are arranged so as to face the heat dissipation pads 22 of the electronic component 2, respectively.

[0016] On the board mounting surface 3a of the circuit board 3, a solder resist 33 is arranged so as to cover at least the area where the lands 31 and heat dissipation lands 32 are not formed. However, the solder resist 33 is arranged so as to cover a part of the surface of the heat dissipation land 32. Hereinafter, the part of the solder resist 33 that covers the surface of the heat dissipation land 32 will be referred to as an over resist 34.

[0017] 3, resist openings 41 are formed for all of the lands 31 so that the entire surface of the land 31 is exposed. Also, resist openings 42 are formed for all of the heat dissipation lands 32 so that the solder resist 33 covers the heat dissipation land 32 near the outer periphery of the heat dissipation land 32. In FIG. 3, the area surrounded by the dashed dotted line corresponds to the over resist 34.

[0018] 1 , the electronic component 2 is placed on the circuit board 3 so that one of the lands 31 faces one of the electrode pads 21, and one of the heat dissipation lands 32 faces one of the heat dissipation pads 22. Then, one of the lands 31 and one of the electrode pads 21 are joined by solder 50 to each of the lands 31. Furthermore, one of the heat dissipation lands 32 and one of the heat dissipation pads 22 are joined by solder 50 to each of the heat dissipation lands 32.

[0019] The electronic device 1 configured in this manner includes an electronic component 2 and a circuit board 3. The electronic component 2 has a plurality of heat dissipation pads 22 on a component mounting surface 2a that faces the circuit board 3 when the electronic component 2 is mounted on the circuit board 3, for dissipating heat generated inside the electronic component 2.

[0020] The circuit board 3 includes one or more heat dissipation lands 32 and an over resist 34 . One or more heat dissipation lands 32 are formed to protrude from the board mounting surface 3a facing the electronic component 2 when the electronic component 2 is mounted on the circuit board 3, and receive heat from one or more heat dissipation pads 22, respectively.

[0021] The over resist 34 is a solder resist 33 placed on the surface of one or more heat dissipation lands 32 so as to cover the surface of one or more heat dissipation lands 32 at least in part around the periphery of the one or more heat dissipation lands 32 and form resist openings 42 on the surface of the one or more heat dissipation lands 32.

[0022] In such an electronic device 1, the over resist 34 is disposed so as to protrude from the surface of the heat dissipation land 32. Therefore, in the electronic device 1, the over resist 34 can restrict the positioning of the electronic component 2 so that the board mounting surface 3a and the component mounting surface 2a do not come close to each other when the electronic component 2 is mounted on the circuit board 3. This prevents the electronic component 2 from tilting relative to the circuit board 3 when the electronic component 2 is mounted on the circuit board 3. Therefore, the electronic device 1 can prevent the solder fillet from becoming bulged, as shown by the solder 50 within the dashed circle in FIG. 1 , for example, and reduce connection failures in the electronic device 1. Note that, if the over resist 34 were not present, the electronic component 2 would be tilted more significantly relative to the circuit board 3 when the electronic component 2 was mounted on the circuit board 3, resulting in the solder fillet becoming bulged, as shown by the solder 50 within the dashed circle in FIG. 4 .

[0023] [Second embodiment] A second embodiment of the present disclosure will be described below with reference to the drawings. In the second embodiment, only the parts that are different from the first embodiment will be described. The same reference numerals will be used to designate common components.

[0024] The electronic device 1 of the second embodiment differs from the first embodiment in that the arrangement of the over resist 34 is changed. 5, in the circuit board 3 of the second embodiment, for each of the four corners (hereinafter referred to as "arrangement corners") of a rectangle formed by the arrangement of a plurality of lands 31, a resist opening 42 is formed so that the corner of the heat dissipation land closest to the arrangement corner among the multiple corners (hereinafter referred to as "heat dissipation land corners") of three heat dissipation lands 32 formed in a rectangular shape in plan view is covered with solder resist 33. In FIG. 5, the area surrounded by the dashed line on the surface of the heat dissipation land corner corresponds to the over resist 34.

[0025] As shown in Figure 6, after applying solder resist 33 so that the entire surface of heat dissipation land 32 is exposed, solder resist 33 is further applied so as to cover the corners of heat dissipation land 32, and over resist 34 is placed on the corners of the heat dissipation land.

[0026] In the electronic device 1 configured in this manner, the over resist 34 is provided so as to cover only the corners of the plurality of heat dissipation lands 32 on the periphery of the plurality of heat dissipation lands 32 formed in a rectangular shape.

[0027] In such an electronic device 1, the over resist 34 is disposed so as to protrude from the surface of the heat dissipation land 32. This prevents the electronic component 2 from tilting relative to the circuit board 3 when the electronic component 2 is mounted on the circuit board 3, thereby preventing the solder fillet from becoming bulged and reducing connection defects in the electronic device 1.

[0028] [Third embodiment] A third embodiment of the present disclosure will be described below with reference to the drawings. In the third embodiment, differences from the first embodiment will be described. The same reference numerals will be used to designate common components.

[0029] The electronic device 1 of the third embodiment differs from the first embodiment in that the arrangement of the over resist 34 is changed. 7, in the circuit board 3 of the third embodiment, a resist opening 42 is formed so that the solder resist 33 covers the heat dissipation lands 32 near the outer periphery facing the lands 31 of the heat dissipation lands 32 that are arranged inside the lands 31 that are arranged to surround the heat dissipation lands 32. In FIG. 7, the area surrounded by the dashed dotted line corresponds to the over resist 34.

[0030] In the electronic device 1 configured in this manner, the over resist 34 is installed so as to cover only the outer periphery of one or more heat dissipation lands 32 that faces the multiple lands 31, which are arranged inside the multiple lands 31 that are arranged to surround the multiple heat dissipation lands 32 on the substrate mounting surface 3a.

[0031] In such an electronic device 1, the over resist 34 is disposed so as to protrude from the surface of the heat dissipation land 32. This prevents the electronic component 2 from tilting relative to the circuit board 3 when the electronic component 2 is mounted on the circuit board 3, thereby preventing the solder fillet from becoming bulged and reducing connection defects in the electronic device 1.

[0032] [Fourth embodiment] A fourth embodiment of the present disclosure will be described below with reference to the drawings. In the fourth embodiment, differences from the first embodiment will be described. The same reference numerals will be used to designate common components.

[0033] The electronic device 1 of the fourth embodiment differs from the first embodiment in that the arrangement of the heat dissipation lands 32 and the arrangement of the over resist 34 are changed. 8, in the circuit board 3 of the fourth embodiment, four heat dissipation lands 32 are arranged on the board mounting surface 3a. A plurality of lands 31 are arranged in a rectangular shape so as to surround these four heat dissipation lands 32.

[0034] One of the four heat dissipation lands 32 (hereinafter referred to as the first heat dissipation land 32a) is positioned near one of the four corners C1 (hereinafter referred to as the first corner C1) of the rectangle formed by the arrangement of multiple lands 31.

[0035] Of the four heat dissipation lands 32, one heat dissipation land 32 (hereinafter referred to as the second heat dissipation land 32b) different from the first heat dissipation land 32a is disposed near one corner C2 (hereinafter referred to as the second corner C2) different from the first corner among the four corners of the rectangle formed by the arrangement of the multiple lands 31. The second corner C2 is a corner facing the first corner C1 along one side constituting the rectangle formed by the arrangement of the multiple lands 31.

[0036] Of the four heat dissipation lands 32, one heat dissipation land 32 different from the first and second heat dissipation lands 32a and 32b (hereinafter referred to as the third heat dissipation land 32c) is disposed near two corners C3 and C4 (hereinafter referred to as the third and fourth corners C3 and C4) different from the first and second corners C1 and C2 of the four corners of the rectangle formed by the arrangement of the multiple lands 31. The third corner C3 is a corner facing the first corner C1 along the diagonal of the rectangle formed by the arrangement of the multiple lands 31. The fourth corner C4 is a corner facing the second corner C2 along the diagonal of the rectangle formed by the arrangement of the multiple lands 31. In other words, the third heat dissipation land 32c is formed to extend from the vicinity of the third corner C3 to the vicinity of the fourth corner C4.

[0037] Of the four heat dissipation lands 32, one heat dissipation land 32 (hereinafter referred to as the fourth heat dissipation land 32d) different from the first, second, and third heat dissipation lands 32a, 32b, and 32c is disposed between the first and second heat dissipation lands 32a and 32b and the third heat dissipation land 32c.

[0038] In the circuit board 3 of the fourth embodiment, for the first, second, and third heat dissipation lands 32a, 32b, and 32c, resist openings 42 are formed near the outer periphery of the heat dissipation land 32 so that the solder resist 33 covers the heat dissipation land 32. For the fourth heat dissipation land 32d, a resist opening 42 is formed so that the entire surface of the heat dissipation land 32 is exposed. In Figure 8, the area surrounded by the dashed line corresponds to the over resist 34.

[0039] In the electronic device 1 configured in this manner, the over resist 34 is provided so as to cover the surfaces of the heat dissipation lands 32 at least in part of the periphery of the heat dissipation lands 32 .

[0040] In such an electronic device 1, the over resist 34 is disposed so as to protrude from the surface of the heat dissipation land 32. This prevents the electronic component 2 from tilting relative to the circuit board 3 when the electronic component 2 is mounted on the circuit board 3, thereby preventing the solder fillet from becoming bulged and reducing connection defects in the electronic device 1.

[0041] [Fifth embodiment] A fifth embodiment of the present disclosure will be described below with reference to the drawings. In the fifth embodiment, differences from the fourth embodiment will be described. The same reference numerals will be used to designate common components.

[0042] As shown in FIG. 9, the electronic device 1 of the fifth embodiment differs from the fourth embodiment in that one heat dissipation land 32 is provided on the circuit board 3, and three protrusions 36, 37, and 38 are provided.

[0043] In the circuit board 3 of the fifth embodiment, the lands 31 are arranged in a rectangular shape so as to surround one heat dissipation land 32 and three protrusions 36, 37, and 38. One heat dissipation land 32 is disposed near the second corner C2.

[0044] The protrusions 36, 37, and 38 are respectively arranged near the first corner C1, the second corner C2, and the fourth corner C4. The protrusions 36 to 38 are patterns made of a metal such as copper, and are formed to be approximately the same height as the heat dissipation land 32.

[0045] In the circuit board 3 of the fifth embodiment, resist openings 42 are formed near the outer periphery of the heat dissipation lands 32 so that the solder resist 33 covers the heat dissipation lands 32. In other words, the solder resist 33 is formed so as to cover the entire surfaces of the protrusions 36 to 38. As a result, the solder resist 33 formed on the protrusions 36 to 38 becomes the over resist 34.

[0046] In the electronic device 1 configured in this manner, the circuit board 3 further includes a plurality of lands 31 and a plurality of protrusions 36, 37, and 38. The multiple lands 31 are arranged on the board mounting surface 3a so as to surround one heat dissipation land 32. The multiple protrusions 36, 37, 38 are arranged inside the multiple lands 31 arranged so as to surround one heat dissipation land 32, so as to protrude from the board mounting surface 3a in an area where no heat dissipation land 32 is arranged.

[0047] The multiple protrusions 36, 37, 38 are arranged so that when the electronic component 2 is mounted on the circuit board 3, the distance between the board mounting surface 3a and the component mounting surface 2a in the area where the over resist 34 is arranged matches the distance between the board mounting surface 3a and the component mounting surface 2a in the area where the multiple protrusions 36, 37, 38 are arranged.

[0048] In such an electronic device 1, the plurality of protrusions 36, 37, and 38 can further prevent the electronic component 2 from tilting relative to the circuit board 3 when the electronic component 2 is mounted on the circuit board 3. Therefore, the electronic device 1 can further prevent the solder fillet from becoming bulged, and can further reduce connection failures in the electronic device 1.

[0049] Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment and can be implemented in various modifications. [Variation 1] In the above embodiment, the electronic component 2 has a QFN structure. However, the electronic component 2 may have a QFP structure. QFP is an abbreviation for Quad Flat Package.

[0050] [Variation 2] In the fifth embodiment, the protrusions 36 to 38 are formed of metal, and the solder resist 33 is formed on the protrusions 36 to 38. However, the protrusions 36 to 38 may be formed of copper, and the solder 50 may be applied to the protrusions 36 to 38 so that the solder 50 on the protrusions 36 to 38 is flush with the over resist 34 on the heat dissipation land 32. Alternatively, the protrusions 36 to 38 may be formed of metal so that the protrusions 36 to 38 are flush with the over resist 34 on the heat dissipation land 32, and the solder resist 33 may not be formed on the protrusions 36 to 38.

[0051] In the above embodiments, multiple functions of one component may be realized by multiple components, or one function of one component may be realized by multiple components. Furthermore, multiple functions of multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Furthermore, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. [Technical idea disclosed in this specification] [Item 1] An electronic device (1) comprising an electronic component (2) and a circuit board (3), The electronic component is one or more heat dissipation pads (22) for dissipating heat generated inside the electronic components on a component mounting surface (2a) facing the circuit board when the electronic components are mounted on the circuit board; The circuit board includes: one or more heat dissipation lands (32) formed to protrude from a board mounting surface (3a) facing the electronic component when the electronic component is mounted on the circuit board, and to receive heat from one or more of the heat dissipation pads, respectively; an over resist (34) which is a solder resist (33) placed on the surface of one or more of the heat dissipation lands so as to cover the surface of one or more of the heat dissipation lands in at least a part of the periphery of the one or more of the heat dissipation lands and to form a resist opening on the surface of the one or more of the heat dissipation lands; An electronic device comprising:

[0052] [Item 2] Item 1, an electronic device according to the present invention, The over resist is the entire periphery of one or more of the heat dissipation lands; or Only the corners of one or more of the heat dissipation lands on the periphery of one or more of the heat dissipation lands formed in a rectangular shape, or Among the peripheries of one or more heat dissipation lands arranged inside a plurality of lands (31) arranged so as to surround one or more of the heat dissipation lands on the board mounting surface, only the peripheries facing the plurality of lands An electronic device that is installed to cover the

[0053] [Item 3] The electronic device according to item 1 or 2, The circuit board further comprises: a plurality of lands (31) arranged on the board mounting surface so as to surround one or more of the heat dissipation lands; one or more protrusions (36, 37, 38) that are arranged inside the lands arranged so as to surround one or more of the heat dissipation lands and that are arranged so as to protrude from the board mounting surface in an area where the heat dissipation lands are not installed, The one or more protrusions may be: An electronic device that is installed so that, when the electronic component is mounted on the circuit board, the distance between the board mounting surface and the component mounting surface in the area where the over resist is installed matches the distance between the board mounting surface and the component mounting surface in the area where one or more protrusions are installed.

[0054] [Item 4] The electronic device according to any one of items 1 to 3, The electronic component is an electronic device having a QFN structure or a QFP structure. [Explanation of symbols]

[0055] 1...electronic device, 2...electronic component, 2a...component mounting surface, 3...circuit board, 3a...board mounting surface, 22...heat dissipation pad, 32...heat dissipation land, 33...solder resist, 34...over resist

Claims

1. An electronic device (1) comprising an electronic component (2) and a circuit board (3), The electronic component is one or more heat dissipation pads (22) for dissipating heat generated inside the electronic components, on a component mounting surface (2a) facing the circuit board when the electronic components are mounted on the circuit board; The circuit board includes: one or more heat dissipation lands (32) formed to protrude from a board mounting surface (3 a) facing the electronic component when the electronic component is mounted on the circuit board, and to receive heat from one or more of the heat dissipation pads, respectively; an over resist (34) which is a solder resist (33) placed on the surface of one or more of the heat dissipation lands so as to cover the surface of one or more of the heat dissipation lands in at least a part of the periphery of the one or more of the heat dissipation lands and to form a resist opening on the surface of the one or more of the heat dissipation lands; An electronic device comprising:

2. 10. The electronic device of claim 1, The over resist is the entire periphery of one or more of the heat dissipation lands, or Only the corners of one or more of the heat dissipation lands on the periphery of one or more of the heat dissipation lands formed in a rectangular shape, or Among the outer peripheries of one or more heat dissipation lands arranged inside a plurality of lands (31) arranged so as to surround one or more of the heat dissipation lands on the board mounting surface, only the outer periphery facing the plurality of lands An electronic device that is installed to cover the

3. 3. The electronic device according to claim 1, The circuit board further comprises: a plurality of lands (31) arranged on the substrate mounting surface so as to surround one or more of the heat dissipation lands; one or more protrusions (36, 37, 38) that are arranged inside the lands arranged so as to surround one or more of the heat dissipation lands and that are arranged so as to protrude from the board mounting surface in an area where the heat dissipation lands are not arranged, The one or more protrusions may be: An electronic device that is installed so that, when the electronic component is mounted on the circuit board, the distance between the board mounting surface and the component mounting surface in the area where the over resist is installed matches the distance between the board mounting surface and the component mounting surface in the area where one or more protrusions are installed.

4. 3. The electronic device according to claim 1, The electronic component is an electronic device having a QFN structure or a QFP structure.

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