JP7618911B2 - Electronic circuit module and manufacturing method - Google Patents

Description

The present invention relates to an electronic circuit module and a manufacturing method.

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 number of case fixing lands on a board along a shield case so that the apex of the solder is located on the outside or inside of a side wall of the shield case, and fixing the shield case to the case fixing lands by soldering. In addition, the following Patent Document 2 discloses a technique for fixing a shield component by soldering to a number of lands arranged alternately on the inside and outside of the shield component along the shield component on a circuit board.

JP 2013-235961 A JP 2015-192076 A

However, with conventional technology, if the circuit board warps, a gap that is not soldered is created between the lower edge of the metal cover and the mounting surface of the circuit board, and there is a risk that electromagnetic noise may enter and leak out through this gap.

An electronic circuit module according to one embodiment 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 in a row along the first land around the entire periphery of the first land on the mounting surface of the circuit board.

According to one embodiment, it is possible to suppress the intrusion and leakage of electromagnetic noise between the lower edge of the metal cover and the mounting surface of the circuit board.

FIG. 1 is an external perspective view of an electronic circuit module according to an embodiment; FIG. 1 is an external perspective view of an electronic circuit module according to an embodiment; FIG. 1 is a partially enlarged view of a circuit board included in an electronic circuit module according to an embodiment; A flowchart showing the steps of a method for manufacturing an electronic circuit module according to an embodiment. FIG. 2 is an external perspective view of a circuit board according to an embodiment (in which a component land, a first land, and a second land are formed); FIG. 2 is a plan view of a circuit board according to an embodiment (in which a component land, a first land, and a second land are formed); FIG. 2 is an external perspective view of a circuit board according to an embodiment (in a state in which a solder layer is formed on the surfaces of the component lands and the second lands); FIG. 2 is a plan view of a circuit board according to an embodiment (in a state in which a solder layer 113 is formed on the surfaces of the component lands and the second lands); FIG. 1 is an external perspective view of a circuit board according to an embodiment (with electronic components mounted on component lands); FIG. 2 is a plan view of a circuit board according to an embodiment (with electronic components mounted on component lands); FIG. 1 is a partially enlarged cross-sectional view of a circuit board and a metal cover according to an embodiment (with cream solder attached to the lower edge of the metal cover); 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 portion of the metal cover is placed on a first land); 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); FIG. 1 is an enlarged plan view of a portion of a circuit board according to an embodiment; FIG. 1 is an enlarged plan view of a portion of a circuit board according to an embodiment;

One 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 may be used upside down, sideways, or at an angle.

(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.

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), and Wi-Fi (registered trademark)) using the electronic circuits contained in the electronic circuit module 100.

As shown in Figures 1 and 2, the electronic circuit module 100 has an overall thin rectangular parallelepiped shape. The electronic circuit module 100 includes a circuit board 110, a number of electronic components 120, and a metal cover 130.

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 an IC 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.

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

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.).

The second lands 112 are arranged on the mounting surface 110A along the first land 111 and on the inner periphery 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 to more securely 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 warps 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.

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.

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

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 suspended 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 portions of the four side wall portions 130B of the metal cover 130 are fixed by soldering to the first land 111 and the multiple second lands 112 around the entire circumference of the first land 111 and are connected to 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.

(Configuration of Arrangement Portion of Second Land 112)
FIG. 3 is a partially enlarged view of the circuit board 110 included in the electronic circuit module 100 according to one embodiment.

As shown in FIG. 3, the first land 111 has a plurality of cutouts 111C formed along the 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.

As a result, the electronic circuit module 100 according to one embodiment is able to bring each of the second lands 112 closer to the lower edge of the metal cover 130 while leaving the first land 111 in a rectangular frame shape. In other words, the electronic circuit module 100 according to one embodiment makes it easier to solder the lower edge of the metal cover 130 to both the first land 111 and the second lands 112.

As shown in FIG. 3, a solder layer 113 is formed on the surface of each of the second lands 112. This allows the solder attached to the lower edge of the metal cover 130 to bond with 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.

As shown in FIG. 3, in this embodiment, each of the second lands 112 has a rectangular shape. However, this is not limited to this, and each of the second lands 112 may have another shape (e.g., a circular shape).

As shown in FIG. 3, in this embodiment, each of the multiple cutouts 111C is formed on the inner peripheral edge 111A of the first land 111, and each of the multiple second lands 112 has a portion provided inside each of the multiple cutouts 111C. However, this is not limited to the above, and each of the multiple cutouts 111C may be formed on the outer peripheral edge 111B of the first land 111, and each of the multiple second lands 112 may have a portion provided inside each of the multiple cutouts 111C.

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.

As shown in FIG. 3, in this embodiment, a plurality of component lands 114 are formed at the respective positions of 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.

(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.

First, as shown in Figures 5A and 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 formation process). Figure 5A is an external perspective view of the circuit board 110 (in which the component lands 114, the first land 111, and the second land 112 have been formed) according to one embodiment. Figure 5B is a plan view of the circuit board 110 (in which the component lands 114, the first land 111, and the second land 112 have been formed) according to one embodiment. As shown in Figures 5A and 5B, in the land formation process, a rectangular frame-shaped first land 111 having multiple cutouts 111C on the inner peripheral edge 111A, multiple second lands 112 arranged in a line along the inner peripheral edge 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.

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

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 (in which electronic components 120 are placed on the component lands 114) according to one embodiment. Figure 7B is a plan view of a circuit board 110 (in which electronic components 120 are placed on the component lands 114) according to one embodiment.

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 process).

Next, as shown in FIG. 8, cream solder 131 is applied around 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 metal cover 130 (with cream solder 131 applied to the lower edge of the metal cover 130) according to one embodiment. For example, cream solder 131 can be applied all at once around the entire circumference of the lower edge of the metal cover 130 by filling a container larger than the metal cover 130 with cream solder 131 and immersing the entire lower edge of the metal cover 130 in the cream solder 131 in the container.

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 placement process). FIG. 9 is a partially enlarged cross-sectional view of the circuit board 110 and the metal cover 130 (with the lower edge of the metal cover 130 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 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. Therefore, as shown in FIG. 9, even if the lower edge of the metal cover 130 with the cream solder 131 attached does not completely land on the first land 111 due to warping of the circuit board 110, the metal cover 130 is placed on the surface of the solder layer 113 of the second land 112, which is higher than the surface of the first land 111.

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 melt, and the lower edge of the metal cover 130 lands on the first land 111 due to the weight of the metal cover 130, 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.

This concludes the description of the manufacturing method for the electronic circuit module 100.

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

<Example of Installation Distance D1 of 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 of the wavelength of the radio waves used by the electronic circuit module 100 (e.g., 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.

<Example of dimensions of first land 111>
11 , in the electronic circuit module 100 according to one embodiment, the first lands 111 have a shape that extends in a strip shape and has a certain width W. As an example, the width W of the first lands 111 is "450 μm."

<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."

<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. 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."

<Example of spacing distance of 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.

(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, which is a portion whose width is narrowed by the cutout portion 111C. An inner edge portion 111Da, which 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, which is the surface on the inner circumference side of the side wall portion 130B of the metal cover 130. This makes it easier to join 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.

When the cutout portion 111C is formed on the outer peripheral edge portion 111B of the first land 111, the outer peripheral edge portion 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 portion 130B of the metal cover 130. In this case, too, it is possible to easily join 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.

As described above, the electronic circuit module 100 according to one embodiment includes 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.

As a result, in the electronic circuit module 100 according to one embodiment, even if warping occurs in the circuit board 110, causing a gap between the lower edge of the metal cover 130 and the first land 111 where no soldering is performed, 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.

In addition, the manufacturing method according to one embodiment includes a land forming process for 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 around the entire periphery of the first land 111, a solder layer forming process for 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 process for mounting an electronic component 120 on the component land 114, and a solder layer 113 on the component land 114 by a reflow method. The method includes a first soldering step of soldering the electronic component 120 to the component land 114 by melting the solder paste 131, a solder attachment step of attaching cream solder 131 to the lower edge of the metal cover 130, a metal cover placement step of placing the metal cover 130 on the first land 111, and a second soldering step of soldering the lower edge of the metal cover 130 to the first land 111 and the multiple second lands 112 by melting the cream solder 131 attached to the lower edge of the metal cover 130 and the solder layer 113 of each of the multiple second lands 112 by a reflow method.

As a result, in the manufacturing method according to one embodiment, even if warping occurs in the circuit board 110, causing a gap between the lower edge of the metal cover 130 and the first land 111 where no soldering is performed, 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 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.

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 alterations are possible within the scope of the gist of the present invention described in the claims.

REFERENCE SIGNS LIST 100 Electronic circuit module 110 Circuit board 110A Mounting surface 111 First land 111A Inner peripheral edge 111B Outer peripheral edge 111C Notch 111D Narrow width portion 111Da Inner edge 112 Second land 113 Solder layer 114 Component land 120 Electronic component 121 IC
130 Metal cover 130A Top plate 130B Side wall 130Ba Inner surface 130Bb Outer surface 131 Cream solder

Claims (9)

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 ,
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: 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,
2 . The electronic circuit module according to claim 1 , wherein at least a portion of each of the second lands is disposed inside each of the cutout portions. The plurality of cutout portions are formed in an inner peripheral edge portion of the first land,
The electronic circuit module according to claim 2 , wherein the second lands are provided on an inner periphery side of the first lands. the first land has a narrow portion that is a portion whose width is narrowed by the cutout portion,
4. The electronic circuit module according to claim 3, wherein an inner peripheral edge of the narrow portion is formed at the same position as an inner peripheral surface of the side wall portion of the metal cover. The plurality of cutout portions are formed in an outer peripheral edge portion of the first land,
The electronic circuit module according to claim 2 , wherein the second lands are provided on an outer periphery of the first lands. the first land has a narrow portion that is a portion whose width is narrowed by the cutout portion,
6. The electronic circuit module according to claim 5, wherein an outer peripheral edge of the narrow portion is formed at the same position as the outer peripheral surface of the side wall portion of the metal cover. 7. The electronic circuit module according to claim 1, wherein a solder layer is formed on a surface of each of the second lands. 8. The electronic circuit module according to claim 1, wherein the second lands are disposed at intervals less than half the wavelength of a radio wave used by the electronic circuit module. 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 plurality of second lands by melting the solder attached to the lower edge of the metal cover and the solder layer of each of the plurality of second lands by a reflow method.

Images