Electronic circuit module and manufacturing method

Abstract

To suppress the intrusion and leakage of electromagnetic wave noise from a gap between the lower edge of a metal cover and the mounting surface of a circuit board.SOLUTION: An electronic circuit module includes a circuit board, a metal cover covering the mounting surface of the circuit board, a first land formed in a frame shape along the lower edge of the metal cover on the mounting surface of the circuit board, and a plurality of second lands formed side by side along the first land over the entire circumference of the first land on the mounting surface of the circuit board.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an electronic circuit module and a manufacturing method. [Background technology]

[0002] Conventionally, a technique for covering the mounting surface of a circuit board with a metal cover is known to suppress the intrusion and leakage of electromagnetic noise into and from electronic components mounted on the circuit board. For example, the following Patent Document 1 discloses a technique for arranging a plurality of case fixing lands on a board along a shielding case so that the apex of the solder is located on the outside or inside of a side wall of the shielding case, and fixing the shielding case to the plurality of case fixing lands by soldering. Also, the following Patent Document 2 discloses a technique for fixing a shielding component by soldering to a plurality of lands arranged alternately on the inside and outside of the shielding component along the shielding component on a circuit board. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-235961 A [Patent Document 2] JP 2015-192076 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional technology, if the circuit board warps, a gap that is not soldered will appear between the lower edge of the metal cover and the mounting surface of the circuit board, and there is a risk that electromagnetic noise will enter and leak out through this gap. [Means for solving the problem]

[0005] An electronic circuit module according to one embodiment comprises a circuit board, a metal cover covering a mounting surface of the circuit board, a first land formed in a frame shape along a lower edge of the metal cover on the mounting surface of the circuit board, and a plurality of second lands formed in a row along the first land around the entire periphery of the first land on the mounting surface of the circuit board. Effect of the Invention

[0006] According to one embodiment, it is possible to suppress the intrusion and leakage of electromagnetic noise from between the lower edge of the metal cover and the mounting surface of the circuit board. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an external perspective view of an electronic circuit module according to an embodiment; [Diagram 2] FIG. 1 is an external perspective view of an electronic circuit module according to an embodiment; [Diagram 3] FIG. 1 is a partially enlarged view of a circuit board included in an electronic circuit module according to an embodiment; [Figure 4] A flowchart showing the steps of a method for manufacturing an electronic circuit module according to an embodiment. [Figure 5A] FIG. 1 is an external perspective view of a circuit board according to one embodiment (in which component lands, first lands, and second lands are formed); [Figure 5B] FIG. 1 is a plan view of a circuit board according to one embodiment (in which component lands, first lands, and second lands are formed); [Figure 6A] FIG. 1 is an external perspective view of a circuit board according to one embodiment (in a state where a solder layer is formed on the surface of the component land and the second land); [Figure 6B] FIG. 1 is a plan view of a circuit board according to one embodiment (in a state in which a solder layer 113 is formed on the surfaces of the component lands and the second lands); [Figure 7A] FIG. 1 is an external perspective view of a circuit board according to an embodiment (with electronic components mounted on component lands); [Figure 7B] FIG. 1 is a plan view of a circuit board according to an embodiment (with electronic components mounted on component lands); [Figure 8]FIG. 1 is a partially enlarged cross-sectional view of a circuit board and a metal cover (with cream solder attached to the lower edge of the metal cover) according to an embodiment; [Figure 9] FIG. 1 is a partially enlarged cross-sectional view of a circuit board and a metal cover according to an embodiment (in a state where a lower edge of the metal cover is placed on a first land); [Figure 10] FIG. 2 is a partially enlarged cross-sectional view of a circuit board and a metal cover according to an embodiment (in a state where a lower edge of the metal cover is soldered to a first land and a second land); [Figure 11] FIG. 1 is a partially enlarged plan view of a circuit board according to an embodiment; [Figure 12] FIG. 1 is a partially enlarged plan view of a circuit board according to an embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An embodiment will be described below with reference to the drawings. In the following description, for the sake of clarity, the side of the circuit board with the mounting surface will be referred to as the upper side and the side with the back side as the lower side. However, this does not limit the orientation of the electronic circuit module when in use, and it is also possible to use the electronic circuit module upside down, sideways, or at an angle.

[0009] (Configuration of electronic circuit module 100) 1 and 2 are external perspective views of an electronic circuit module 100 according to an embodiment. Fig. 1 shows the electronic circuit module 100 after a metal cover 130 is fixed to a circuit board 110. Fig. 2 shows the electronic circuit module 100 before the metal cover 130 is fixed to the circuit board 110.

[0010] The electronic circuit module 100 shown in Figures 1 and 2 is a device that is implemented in various electrical products to realize specific functions (e.g., wireless communication functions such as LTE (Long Term Evolution) (registered trademark), Bluetooth (registered trademark), Wi-Fi (registered trademark), etc.) by the electronic circuits provided in the electronic circuit module 100.

[0011] 1 and 2, the electronic circuit module 100 has a generally thin rectangular parallelepiped shape. The electronic circuit module 100 includes a circuit board 110, a plurality of electronic components 120, and a metal cover .

[0012] The circuit board 110 is a flat, rectangular member. The surface of the circuit board 110 is a mounting surface 110A on which a plurality of electronic components 120 including ICs 121 are mounted. For example, a PWB (Printed Wiring Board) is used as the circuit board 110. For example, the circuit board 110 is formed by using an insulating resin for its flat base material.

[0013] As shown in FIG. 2, a first land 111 and a plurality of second lands 112 are formed on the mounting surface 110A.

[0014] The first land 111 is an electrode formed in a rectangular frame shape along the outer periphery of the mounting surface 110A and the lower edge of the metal cover 130 so as to surround the multiple electronic components 120. The first land 111 is formed facing the lower edge of the metal cover 130, and has a frame shape of the same shape (i.e., rectangular in this embodiment) and size as the lower edge of the metal cover 130. The lower edge of the metal cover 130 is fixed to the first land 111 by soldering. For example, the first land 111 is formed using various conductive films (e.g., copper foil, etc.).

[0015] The second lands 112 are arranged on the mounting surface 110A along the first land 111 and on the inner periphery side of the first land 111. Each of the second lands 112 is a rectangular electrode. The second lands 112 are provided as auxiliary lands to the first land 111 in order to more reliably fix the metal cover 130. The second lands 112 are provided close to the first land 111 so that even if the circuit board 110 is warped and a part of the lower edge of the metal cover 130 cannot be soldered to the first land 111, the second lands 112 can be soldered to the second land 112.

[0016] The electronic components 120 include an IC (Integrated Circuit) 121. The IC 121 is a main component of the electronic circuit of the electronic circuit module 100. The IC 121 is mounted on the mounting surface 110A of the circuit board 110. For example, the IC 121 is configured to include a communication circuit, a processor, a memory, and the like. For example, the IC 121 realizes various functions of the electronic circuit module 100 by the processor executing a program stored in the memory. In this embodiment, a communication IC in which an integrated circuit element is sealed with insulating resin is used as the IC 121.

[0017] In this embodiment, an IC 121 is used as an example of an electronic component 120 to be mounted on mounting surface 110A, but this is not limited thereto, and other electronic components 120 (e.g., passive components such as resistors, inductors, and capacitors) and wiring components, etc. may also be mounted on mounting surface 110A.

[0018] The metal cover 130 is a metal member that covers the mounting surface 110A of the circuit board 110. The metal cover 130 has a rectangular top plate portion 130A that faces the mounting surface 110A of the circuit board 110, and four side wall portions 130B that are vertically arranged downward (toward the mounting surface 110A) from each of the four sides of the top plate portion 130A. The metal cover 130 has a thin rectangular parallelepiped shape with an opening at the bottom. The lower edge portion of each of the four side wall portions 130B of the metal cover 130 is fixed to the first land 111 and the multiple second lands 112 by soldering around the entire circumference of the first land 111 and is connected to the ground. The metal cover 130 covers the mounting surface 110A of the circuit board 110, thereby protecting the multiple electronic components 120 from external impacts and the like, and suppressing the leakage of electromagnetic noise from the IC 121 and the intrusion of electromagnetic noise into the IC 121. The metal cover 130 is formed by pressing a metal plate such as iron.

[0019] (Configuration of the arrangement of the second land 112) FIG. 3 is a partially enlarged view of a circuit board 110 included in the electronic circuit module 100 according to one embodiment.

[0020] 3, the first land 111 has a plurality of cutouts 111C formed along an inner peripheral edge 111A of the first land 111 all around the first land 111. Each of the cutouts 111C has a shape cut out from the inner peripheral edge 111A of the first land 111 toward the outer peripheral edge 111B of the first land 111, thereby partially narrowing the width of the first land 111. A portion of each of the second lands 112 is provided inside each of the cutouts 111C, and is provided at a predetermined distance from the inner edge of the cutout 111C.

[0021] As a result, in the electronic circuit module 100 according to one embodiment, each of the multiple second lands 112 can be brought closer to the lower edge of the metal cover 130 while leaving the first lands 111 in a rectangular frame shape. That is, in the electronic circuit module 100 according to one embodiment, the lower edge of the metal cover 130 can be easily soldered to both the first lands 111 and the multiple second lands 112.

[0022] 3, a solder layer 113 is formed on the surface of each of the second lands 112. As a result, the solder attached to the lower edge of the metal cover 130 is bonded to the solder layer 113 formed on the second lands 112, making it easier to connect the lower edge of the metal cover 130 to the second lands 112.

[0023] 3, in this embodiment, each of the second lands 112 has a rectangular shape. However, this is not limited thereto, and each of the second lands 112 may have another shape (for example, a circular shape).

[0024] 3, in this embodiment, each of the plurality of cutout portions 111C is formed in the inner peripheral edge portion 111A of the first land 111, and a portion of each of the plurality of second lands 112 is provided inside each of the plurality of cutout portions 111C. However, this is not limited thereto, and each of the plurality of cutout portions 111C may be formed in the outer peripheral edge portion 111B of the first land 111, and a portion of each of the plurality of second lands 112 may be provided inside each of the plurality of cutout portions 111C.

[0025] That is, in this embodiment, the multiple second lands 112 are arranged side by side on the inner periphery side of the first land 111, but this is not limited thereto, and the multiple second lands 112 may be arranged side by side on the outer periphery side of the first land.

[0026] 3, in this embodiment, a plurality of component lands 114 are formed at positions corresponding to the plurality of electronic components 120 on the mounting surface 110A of the circuit board 110. A solder layer 113 for soldering the electronic components 120 is formed on the surface of each of the plurality of component lands 114.

[0027] (Method of Manufacturing Electronic Circuit Module 100) FIG. 4 is a flowchart showing the steps of a method for manufacturing the electronic circuit module 100 according to an embodiment.

[0028] First, as shown in Fig. 5A and Fig. 5B, a plurality of component lands 114, a first land 111, and a plurality of second lands 112 are formed on the mounting surface 110A of the circuit board 110 (step S401: land forming process). Fig. 5A is an external perspective view of the circuit board 110 according to one embodiment (in a state in which the component lands 114, the first land 111, and the second land 112 have been formed). Fig. 5B is a plan view of the circuit board 110 according to one embodiment (in a state in which the component lands 114, the first land 111, and the second land 112 have been formed). As shown in Figures 5A and 5B, in the land formation process, a rectangular frame-shaped first land 111 having multiple cutout portions 111C on an inner periphery 111A, multiple second lands 112 arranged in a line along the inner periphery 111A of the first land 111, and multiple component lands 114 arranged inside the first land 111 are formed on the mounting surface 110A of the circuit board 110.

[0029] Next, as shown in Figures 6A and 6B, cream solder is applied to the surfaces of each of the component lands 114 and the second lands 112 to form a solder layer 113 (step S402: solder layer forming process). Figure 6A is an external perspective view of a circuit board 110 according to one embodiment (in a state where the solder layer 113 is formed on the surfaces of the component lands 114 and the second lands 112). Figure 6B is a plan view of a circuit board 110 according to one embodiment (in a state where the solder layer 113 is formed on the surfaces of the component lands 114 and the second lands 112).

[0030] Next, as shown in Figures 7A and 7B, a plurality of electronic components 120 (including ICs 121) are placed on each of the plurality of component lands 114 (step S403: electronic component placement process). Figure 7A is an external perspective view of a circuit board 110 according to one embodiment (in a state in which electronic components 120 are placed on component lands 114). Figure 7B is a plan view of a circuit board 110 according to one embodiment (in a state in which electronic components 120 are placed on component lands 114).

[0031] Next, the solder layer 113 of each of the component lands 114 is heated and melted by a reflow method, thereby soldering each of the electronic components 120 to each of the component lands 114 (step S404: first soldering step).

[0032] Next, as shown in Fig. 8, cream solder 131 is applied to the entire circumference of the lower edge of the metal cover 130 (step S405: solder application process). Fig. 8 is a partially enlarged cross-sectional view of the circuit board 110 and the metal cover 130 (with the cream solder 131 applied to the lower edge of the metal cover 130) according to one embodiment. For example, the cream solder 131 can be applied to the entire circumference of the lower edge of the metal cover 130 all at once by filling a container larger than the metal cover 130 with the cream solder 131 and immersing the entire lower edge of the metal cover 130 in the cream solder 131 in the container.

[0033] Next, as shown in FIG. 9, the lower edge of the metal cover 130 with the cream solder 131 attached thereto is placed on the first land 111 (step S406: metal cover placing process). FIG. 9 is a partially enlarged cross-sectional view of the circuit board 110 and the metal cover 130 (in a state where the lower edge of the metal cover 130 is placed on the first land 111) according to one embodiment. As shown in FIG. 9, the second land 112 is provided on the inner periphery side of the first land 111, and the solder layer 113 is formed on the surface of the second land 112. The height position of the surface of the solder layer 113 is higher than the height position of the surface of the first land 111. Furthermore, the solder layer 113 is cooled and solidified after step S404: first soldering process. For this reason, as shown in FIG. 9, even if the lower edge of the metal cover 130 with the cream solder 131 attached thereto does not land completely on the first land 111 due to warping of the circuit board 110, the metal cover 130 will be placed on the surface of the solder layer 113 of the second land 112, which is higher than the height position of the surface of the first land 111.

[0034] 10, the cream solder 131 attached to the lower edge of the metal cover 130 and the solder layer 113 of each of the second lands 112 are heated and melted by a reflow method to solder the metal cover 130 to the first land 111 and the second lands 112 (step S407: second soldering process). FIG. 10 is a partially enlarged cross-sectional view of the circuit board 110 and the metal cover 130 (in a state in which the lower edge of the metal cover 130 is soldered to the first land 111 and the second land 112) according to one embodiment. As shown in FIG. 10, the cream solder 131 and the solder layer 113 are melted, and the lower edge of the metal cover 130 lands on the first land 111 due to its own weight, and is soldered to the first land 111 via the cream solder 131. Furthermore, by fusing the cream solder 131 and the solder layer 113 together, the lower edge of the metal cover 130 is also soldered to the second land 112 via the cream solder 131 and the solder layer 113 (see part A in FIG. 10). Therefore, even if a gap occurs between the lower edge of the metal cover 130 and the first land 111 due to warping of the circuit board 110, the gap can be partially filled and the width of the gap can be made less than half the wavelength. This makes it possible to suppress the intrusion and leakage of electromagnetic noise from the gap.

[0035] This completes the description of the manufacturing method for the electronic circuit module 100.

[0036] (Example dimensions of each part) An example of dimensions of each portion of the circuit board 110 according to one embodiment will be described below with reference to Fig. 11. Fig. 11 is a partially enlarged plan view of the circuit board 110 according to one embodiment.

[0037] <An example of the installation interval D1 of the second lands 112> 11, in the electronic circuit module 100 according to an embodiment, a plurality of second lands 112 are arranged side by side with a predetermined installation interval D1. In particular, in the electronic circuit module 100 according to an embodiment, the installation interval D1 of the second lands 112 is less than ½ the wavelength of the radio waves used by the electronic circuit module 100 (for example, less than 1.5 mm). As a result, in the electronic circuit module 100 according to an embodiment, even if a gap occurs between the lower edge of the metal cover 130 and the mounting surface 110A of the circuit board 110 between two adjacent second lands 112, radio waves are prevented from leaking out from the gap.

[0038] <Example of dimensions of the first land 111> 11, in an electronic circuit module 100 according to one embodiment, the first lands 111 extend in a strip shape with a certain width W. As an example, the width W of the first lands 111 is "450 μm."

[0039] <Example of dimensions of second land 112> 11, in the electronic circuit module 100 according to one embodiment, the second lands 112 have a rectangular shape. As an example, the width W1 of the second lands 112 in a direction parallel to the extension direction of the first lands 111 is "300 μm," and the width W2 of the second lands 112 in a direction perpendicular to the extension direction of the first lands 111 is "200 μm."

[0040] <Example of dimensions of cutout portion 111C> 11, in the electronic circuit module 100 according to one embodiment, the cutout portion 111C has a rectangular shape capable of accommodating a part of the second land 112 therein. As an example, the width W3 of the cutout portion 111C in a direction parallel to the extension direction of the first land 111 is "450 μm," and the width W4 of the cutout portion 111C in a direction perpendicular to the extension direction of the first land 111 is "125 μm."

[0041] <An example of the spacing distance of the second lands 112> 11, the second land 112 is provided inside the cutout portion 111C at a predetermined distance D2 from the cutout portion 111C. As an example, the distance D2 is 75 μm.

[0042] (Positional Relationship Between Metal Cover 130 and Cutout Portion 111C) 12 is a partially enlarged plan view of the circuit board 110 according to an embodiment. In FIG. 12, the arrangement position of the side wall portion 130B of the metal cover 130 is shown overlapping. As shown in FIG. 12, the first land 111 has a narrow width portion 111D that is a portion whose width is narrowed by the cutout portion 111C. An inner edge portion 111Da that is an edge portion on the inner circumference side of the narrow width portion 111D is formed at the same position as an inner surface 130Ba that is a surface on the inner circumference side of the side wall portion 130B of the metal cover 130. This makes it easier to bond the cream solder 131 applied to the lower edge portion of the metal cover 130 to the solder layer 113 formed on the surface of the second land 112.

[0043] When the notch 111C is formed on the outer peripheral edge 111B of the first land 111, the outer peripheral edge of the narrow width portion 111D may be formed at the same position as the outer surface 130Bb, which is the outer peripheral surface of the side wall 130B of the metal cover 130. In this case as well, the cream solder 131 applied to the lower edge of the metal cover 130 can be easily joined to the solder layer 113 formed on the surface of the second land 112.

[0044] As described above, the electronic circuit module 100 of one embodiment comprises a circuit board 110, a metal cover 130 covering the mounting surface 110A of the circuit board 110, a first land 111 formed in a frame shape along the lower edge of the metal cover 130 on the mounting surface 110A of the circuit board 110, and a plurality of second lands 112 formed in a row along the first land 111 around the entire circumference of the first land 111 on the mounting surface 110A of the circuit board 110.

[0045] As a result, in the electronic circuit module 100 according to one embodiment, even if warping occurs in the circuit board 110 and a gap where no soldering is performed occurs between the lower edge of the metal cover 130 and the first land 111, the gap can be partially filled by soldering the lower edge of the metal cover 130 to the second land 112. Therefore, according to the electronic circuit module 100 according to one embodiment, it is possible to suppress the intrusion and leakage of electromagnetic noise from between the lower edge of the metal cover 130 and the mounting surface 110A of the circuit board 110.

[0046] Moreover, the manufacturing method according to the embodiment includes a land forming step of forming, on the mounting surface 110A of the circuit board 110, a component land 114, a frame-shaped first land 111 along the lower edge of the metal cover 130, and a plurality of second lands 112 arranged in a line along the first land 111 over the entire periphery of the first land 111, a solder layer forming step of forming a solder layer 113 on the surface of each of the component land 114 and the plurality of second lands 112, an electronic component mounting step of mounting an electronic component 120 on the component land 114, and a solder layer 112 on the component land 114 by a reflow method. the first soldering step of soldering the electronic component 120 to the component land 114 by melting solder layer 3; the solder attachment step of attaching cream solder 131 to the lower edge portion of the metal cover 130; the metal cover placement step of placing the metal cover 130 on the first lands 111; and the second soldering step of soldering the lower edge portion of the metal cover 130 to the first lands 111 and the plurality of second lands 112 by melting the cream solder 131 attached to the lower edge portion of the metal cover 130 and the solder layer 113 of each of the plurality of second lands 112 by a reflow method.

[0047] As a result, in the manufacturing method according to one embodiment, even if warping occurs in the circuit board 110 and a gap where no soldering is performed occurs between the lower edge of the metal cover 130 and the first land 111, the gap can be partially filled by soldering the lower edge of the metal cover 130 and the second land 112. Therefore, according to the manufacturing method according to one embodiment, it is possible to suppress the intrusion and leakage of electromagnetic noise from between the lower edge of the metal cover 130 and the mounting surface 110A of the circuit board 110.

[0048] 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. [Explanation of symbols]

[0049] 100 Electronic Circuit Module 110 Circuit Board 110A Mounting surface 111 Land 1 111A Inner edge 111B Outer edge 111C Cutout 111D Narrow part 111Da inner edge 112 Land 2 113 Solder layer 114 Parts Land 120 Electronic Components 121 IC 130 Metal Cover 130A Top plate 130B Side wall part 130Ba inner surface 130Bb outer surface 131 Cream solder

Claims

1. A circuit board; a metal cover for covering a mounting surface of the circuit board; a first land formed in a frame shape along a lower edge portion of the metal cover on the mounting surface of the circuit board; a plurality of second lands formed on the mounting surface of the circuit board so as to be aligned along the first lands and around the entire periphery of the first lands; Equipped with A lower edge of the metal cover is fixed to the first land and the plurality of second lands by soldering.

1. An electronic circuit module comprising:

2. The first land is The first land has a plurality of cutout portions that partially narrow the width of the first land over an entire periphery thereof, At least a portion of each of the second lands is disposed inside each of the cutout portions.

2. The electronic circuit module according to claim 1.

3. The plurality of cutout portions are formed in an inner peripheral edge portion of the first land, The second lands are provided on the inner circumferential side of the first lands.

3. The electronic circuit module according to claim 2.

4. the first land has a narrow portion that is a portion whose width is narrowed by the cutout portion, The inner peripheral edge of the narrow width portion is formed at the same position as the inner peripheral surface of the side wall portion of the metal cover.

4. The electronic circuit module according to claim 3.

5. The plurality of cutout portions are formed in an outer peripheral edge portion of the first land, The second lands are provided on the outer circumferential side of the first lands.

3. The electronic circuit module according to claim 2.

6. the first land has a narrow portion that is a portion whose width is narrowed by the cutout portion, The edge of the narrow portion on the outer periphery is formed at the same position as the outer periphery surface of the side wall of the metal cover.

6. The electronic circuit module according to claim 5.

7. A solder layer is formed on a surface of each of the second lands.

7. The electronic circuit module according to claim 1, wherein the first and second electrodes are electrically connected to each other.

8. The interval between the second lands is less than half the wavelength of the radio wave used by the electronic circuit module.

8. The electronic circuit module according to claim 1, wherein the first and second electrodes are electrically connected to the first and second electrodes.

9. a land forming process for forming, on a mounting surface of a circuit board, a component land, a frame-shaped first land along a lower edge portion of a metal cover, and a plurality of second lands arranged in line along the first land over the entire periphery of the first land; a solder layer forming step of forming a solder layer on a surface of each of the component lands and the plurality of second lands; an electronic component mounting step of mounting an electronic component on the component land; a first soldering step of soldering the electronic component to the component land by melting the solder layer of the component land by a reflow method; a solder attachment step of attaching solder to a lower edge portion of the metal cover; a metal cover placing step of placing the metal cover on the first land; a second soldering step of soldering the lower edge of the metal cover to the first land and the second lands by melting the solder attached to the lower edge of the metal cover and the solder layer of each of the second lands by a reflow method; A manufacturing method comprising:

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