JP7456830B2 - circuit module - Google Patents

Description

The present invention relates to a circuit module in which components are mounted on a circuit board and sealed.

In recent years, circuit boards on which digital circuits and analog circuits are mixedly mounted have been widely used. In such a circuit board, each frequency component of the analog circuit signal changes continuously from time to time, and it is necessary to faithfully transmit this to the digital circuit section or external components. On the other hand, digital circuits have higher signal levels than analog circuits, and because they are pulses, there are many harmonic components. Therefore, it is necessary to prevent analog circuits from being mixed with signals from digital circuits. Therefore, circuit boards on which digital circuits and analog circuits are mounted separately are widely used.

In order to prevent interference (electromagnetic interference) caused by electromagnetic waves inside and outside the circuit module, a configuration is adopted in which an electromagnetic shield is formed by a metal case, or an electromagnetic shield is formed on a sealing body that covers the mounted components. . When forming an electromagnetic shield using a metal case, a soldering land for attaching the metal case is required on the surface of the board, which poses an obstacle to miniaturizing the circuit module. On the other hand, in order to prevent electromagnetic interference between mounted components when an electromagnetic shield is formed on the sealing body that covers the mounted components, circuit modules have also been developed in which an internal shield is provided to separate the mounted components. . In addition, since the mounted component is covered with the sealing body as described above, the sealing body is partially removed to form a trench, and a conductor is formed in the trench, thereby making the inside of the above-mentioned Can be used as a shield.

For example, a circuit module is known in which a trench is formed in a sealed body that covers a plurality of mounted components and extends to the inside of a circuit board, and a conductor is formed in the trench (see, for example, Patent Document 1). Further, a circuit module is known in which a trench extending to a surface wiring layer of a circuit board is formed on a sealing body that covers a mounted component, and a conductor is formed in the trench (for example, see Patent Document 2).

Japanese Patent Application Publication No. 2010-225620 Japanese Patent Application Publication No. 2015-53298

However, in the circuit module configured as described above, the electromagnetic shield of the digital circuit section and the electromagnetic shield of the analog circuit section are electrically coupled, so there is a risk that signals from the digital circuit will mix into the analog circuit via the electromagnetic shield. There is.

In view of the above circumstances, an object of the present invention is to provide a circuit module that can prevent signals from being mixed between a plurality of circuit areas on a substrate.

A circuit module according to one embodiment of the present invention includes a circuit board, a plurality of electronic components, a sealing body, a first shield, and a second shield.
The circuit board has a component mounting surface, a first conductive pattern, and a second conductive pattern. The component mounting surface has a first circuit area and a second circuit area. The first conductor pattern is provided on the component mounting surface and defines the first circuit area. The second conductor pattern is provided on the component mounting surface and defines the second circuit area.
The plurality of electronic components are mounted in the first circuit area and the second circuit area.
The sealing body is provided in the first circuit area and the second circuit area, and covers the plurality of mounted components.
The first shield is made of a conductive material. The first shield has a first outer shield part and a first inner shield part. The first external shield portion is provided on the top surface of the sealing body. The first inner shield portion connects the first outer shield portion to the first conductor pattern, and at least a portion thereof is disposed inside the sealing body.
The second shield is made of a conductive material and is electrically isolated from the first shield. The second shield has a second outer shield portion and a second inner shield portion. The second external shield portion is provided on the top surface of the sealing body. The second internal shield part connects the second external shield part to the second conductor pattern, and is at least partially disposed inside the sealing body.

The circuit board includes a first ground wiring connected to the first conductive pattern, and a second ground wiring connected to the second conductive pattern and electrically separated from the first ground wiring. , may further include.

The first internal shield portion may be formed in a cylindrical shape having at least four side surfaces that hang down from the first external shield portion toward the component mounting surface. Similarly, the second internal shield portion may be formed in a cylindrical shape having at least four side surfaces that hang down from the second external shield portion toward the component mounting surface.

At least four sides of the first internal shield part and the second internal shield part may be covered with the sealing body.

The first outer shield part may have an extension part extending further outward of the first circuit area than the first inner shield part. Similarly, the second outer shield part may have an extension part that extends further outside the second circuit area than the second inner shield part.

The sealing body may have a groove provided on the top surface and separating the first external shield part and the second external shield part from each other.

The groove portion may be formed with a depth that reaches the component mounting surface from the top surface.

A digital circuit may be formed in the first circuit area, and an analog circuit may be formed in the second circuit area.

According to the present invention, it is possible to prevent signals from being mixed between a plurality of circuit areas on a substrate.

FIG. 1 is a perspective view of a circuit module according to a first embodiment of the present invention. It is a top view of the said circuit module. 3 is a cross-sectional view taken along line AA in FIG. 2. FIG. 2A to 2C are process diagrams showing a method for manufacturing the circuit module shown in FIG. 1 . 2 is a process diagram showing a method for manufacturing the circuit module shown in FIG. 1. FIG. FIG. 11 is a perspective view of a circuit module according to a second embodiment of the present invention. 7 is a cross-sectional view of the circuit module of FIG. 6. FIG.

A circuit module according to an embodiment of the present invention will be described.

<First embodiment>
FIG. 1 is a perspective view showing a circuit module 100 according to an embodiment of the invention. FIG. 2 is a plan view of the circuit module 100. FIG. 3 is a cross-sectional view taken along line AA in FIG.
In each figure, the X-axis direction, Y-axis direction, and Z-axis direction indicate directions perpendicular to each other, and the Z-axis direction corresponds to the thickness direction (vertical direction) of the circuit module.
The configuration of the circuit module 100 will be described below with reference to FIGS. 1 to 3.

[Circuit module configuration]
The circuit module 100 of this embodiment includes a circuit board 10, a plurality of mounted components (21, 22), a sealing body 30, a first shield 41, and a second shield 42.

The circuit module 100 includes a first mounting component 21 and a second mounting component 22 mounted on a component mounting surface B of a circuit board 10, and a sealing body 30 and first and second shields 41 to cover them. , 42 are formed. The plurality of mounted components is not limited to the first and second mounted components 21, and may be three or more. Although the size and shape of the circuit module 100 are not particularly limited, it may be, for example, a rectangular parallelepiped with several tens of mm square and several mm thick.

(circuit board)
The circuit board 10 is a multilayer wiring board. The material constituting the wiring layer of the circuit board 10 is typically made of metal foil such as copper foil. Each wiring layer is composed of a wiring pattern having a predetermined shape. The material constituting the insulating layer of the circuit board 10 is typically a glass epoxy material, but is not limited thereto; for example, an insulating ceramic material can also be used.

The front surface (upper surface in FIG. 1) of the circuit board 10 forms a component mounting surface B on which the first and second mounted components 21 and 22 are mounted. The component mounting surface B has a first circuit area B1 and a second circuit area B2 (see FIG. 2). As shown in FIG. 3, the first circuit area B1 is provided with a plurality of land parts 111 on which the first mounted components 21 are mounted, and the second circuit area B2 is provided with a plurality of land parts 111 on which the second mounted components 21 are mounted. A plurality of land portions 112 are provided. The land portions 111 and 112 are formed as part of the wiring pattern located on the top layer of the circuit board 10 in FIG.

On the other hand, a plurality of external connection terminals 113 are provided on the back surface (lower surface in FIG. 1) of the circuit board 10 to be electrically connected to a motherboard (not shown). The external connection terminal 113 is formed as a part of the wiring pattern located at the bottom layer of the circuit board 10 in FIG. Furthermore, a plurality of wiring layers 114 are formed inside the circuit board 10 to electrically connect between the land portions 111 and 112 on the front surface and the external connection terminals 113 on the back surface.

The first circuit area B1 and the second circuit area B2 each constitute a part of an independent electric circuit. The electric circuit may be an analog circuit or a digital circuit. In this embodiment, the first circuit area B1 constitutes at least a part of the digital circuit, and the second circuit area B2 constitutes at least a part of the analog circuit.

On the component mounting surface B, a first conductor pattern 121 that partitions a first circuit area B1 and a second conductor pattern 122 that partitions a second circuit area B2 are formed. The first and second conductor patterns 121 and 122 are mutually independent wiring patterns, and are each formed in a rectangular frame shape.

As shown in FIG. 2, the first and second shields 41 and 42 are spaced apart in the X-axis direction. Although the shapes and sizes of the first and second shields 41 and 42 are the same, they are of course not limited to this. The first and second conductor patterns 121 and 122 are connected to inner shield portions 412 and 422 of shields 41 and 42, respectively. The land portion 111 on which the first mounted component 21 is mounted is provided inside the area surrounded by the first conductive pattern 121, and the land portion 112 on which the second mounted component 22 is mounted is provided on the inside of the area surrounded by the first conductive pattern 121. It is provided inside the area surrounded by the pattern 122 (see FIG. 3). Note that when there are three or more circuit areas, three or more conductor patterns are also provided correspondingly.

As shown in FIG. 3, a first ground wiring 131 connected to the first conductive pattern 121 and a second ground wiring 132 connected to the second conductive pattern 122 are formed on the circuit board 10. Ru. The formation positions of the first and second ground wirings 131 and 132 are not particularly limited. For example, the first ground wiring 131 is formed in the inner layer part on one side (the left side in FIG. 3) of the circuit board 10, and the second The ground wiring 132 is formed in the inner layer on the other side (the right side in FIG. 3) of the circuit board 10.

The first and second ground wirings 131 and 132 are electrically isolated from each other and form independent ground lines. connected to. The external connection terminals 113 for ground connection may be two terminals corresponding to each ground line, or may be one terminal common to each ground line. The position of the ground line is also not particularly limited, and may be formed inside the circuit board 10 or on the side surface of the circuit board 10.

(Mounting parts)
The first and second mounted components 21 and 22 are both electronic components mounted on the component mounting surface B of the circuit board 10, such as integrated circuits (ICs), capacitors, inductors, resistors, crystal oscillators, etc. devices, duplexers, filters, power amplifiers, etc. In this embodiment, the first mounted component 21 is an electronic component that constitutes a part of a digital circuit formed in the first circuit area B1, and the second mounted component 22 is an electronic component that constitutes a part of a digital circuit formed in the first circuit area B1. It is an electronic component that forms part of an analog circuit formed in

(sealed body)
The sealing body 30 is formed on the component mounting surface B of the circuit board 10 and covers the first mounted component 21 and the second mounted component 22. The sealing body 30 is formed of a sealing material made of an insulating synthetic resin material. Specifically, thermosetting resins such as epoxy resins can be applied to the sealing material, and fillers such as silica, alumina, and glass fibers may be added for the purpose of adjusting the strength and coefficient of thermal expansion. good. Formation of the sealing body 30 improves the strength of the circuit module 100, so that breakage due to external forces and damage to the mounted components 21 and 22 can be prevented. Furthermore, since the component mounting surface B is sealed with the sealing body 30, it is possible to prevent moisture, dust, etc. from adhering to the circuit areas B1 and B2, thereby ensuring stable operation of the circuit module 100. .

The sealing body 30 is formed in a rectangular parallelepiped shape with the same width (size in the X-axis direction) and length (size in the Y-axis direction) as the circuit board 10 . The thickness of the sealing body 30 (size in the Z-axis direction) is not particularly limited, and may be any thickness that can cover at least the first and second mounted components 21 and 22. The top surface 301 of the sealing body 30 is formed as a plane parallel to the component mounting surface B.

(1st shield and 2nd shield)
The first shield 41 has an outer shield part 411 (first outer shield part) and an inner shield part 412 (first inner shield part). The outer shield part 411 and the inner shield part 412 are made of a conductive material and are formed to three-dimensionally surround the entire area of the first circuit area B1 including the first mounted component 21.

The external shield portion 411 is provided on the top surface 301 of the sealing body 30, and is particularly formed in a region of the top surface 301 facing the first circuit region B1 in the Z-axis direction. The inner shield part 412 is arranged inside the sealing body 30 so as to connect the outer shield part 411 to the first conductor pattern 121. In this embodiment, the internal shield part 412 is formed into a cylindrical shape having at least four side surfaces that hang down from the external shield part 411 toward the component mounting surface B, so that the first circuit area B1 is covered by the internal shield part 412. Be surrounded. In addition to the square cylinder shape with four sides, the cylinder shape includes a polygonal cylinder shape such as a pentagon with five sides, an L-shaped cylinder shape with a part of the square cylinder shape cut out, and a cylinder shape with six sides. It may also be a cylindrical shape with eight sides in the shape of a square. This increases the degree of freedom in designing the shape of the circuit module and the arrangement of components, making it possible to reduce the size and material costs associated with miniaturization.

The second shield 42 has an outer shield part 421 (second outer shield part) and an inner shield part 422 (second inner shield part). The outer shield part 421 and the inner shield part 422 are made of a conductive material and are formed to three-dimensionally surround the entire second circuit area B2 including the second mounted component 22. The second shield 42 is electrically isolated from the first shield 41.

The external shield portion 421 is provided on the top surface 301 of the sealing body 30, and is particularly formed in a region of the top surface 301 facing the second circuit region B2 in the Z-axis direction. The inner shield part 422 is arranged inside the sealing body 30 so as to connect the outer shield part 421 to the second conductor pattern 122. In this embodiment, the internal shield part 422 is formed into a cylindrical shape having at least four side surfaces that hang down from the external shield part 421 toward the component mounting surface B, so that the second circuit area B2 is covered by the internal shield part 422. Be surrounded.

As the conductive material constituting the first shield 41 and the second shield 42, a conductive resin material such as a cured conductive paste is typically used. As the conductive paste, a composite material containing conductive particles such as Ag or Cu in a thermosetting resin material such as epoxy resin can be used. In addition to the conductive paste, the conductive material may be a metal film formed by sputtering, vacuum evaporation, or the like.

The external shield parts 411 and 421 are formed by forming a conductor layer made of a conductive resin material on the top surface 301 of the sealing body 30 and then forming a groove 302 on the top surface 301 of the sealing body 30, as described later. are separated from each other. The groove portion 302 is formed linearly in parallel to the Y-axis direction, and its depth may be greater than the thickness of the conductor layer forming the outer shield portions 411 and 421. The width of the groove portion 302 along the X-axis direction is also not particularly limited, as long as it is smaller than the distance between the inner shield portion 412 of the first shield 41 and the inner shield portion 422 of the second shield 42 . The depth of the groove portion 302 along the Z-axis direction is less than half the thickness of the sealing body 30 . Thereby, the bending strength of the sealing body 30 can be maintained. Note that the groove portion 302 is not limited to the square groove shape shown in the figure, but may have other shapes such as a round groove or a V-shaped groove.

The internal shield parts 412 and 422 are formed by forming a linear trench penetrating the sealing body 30 in the thickness direction thereof and filling the inside of the trench with a conductive resin material, as will be described later. The trench forming the inner shield portion 412 is formed in a rectangular ring shape corresponding to the first conductor pattern 121, and the trench forming the inner shield portion 422 is formed in a rectangular ring shape corresponding to the second conductor pattern 122. . The method of forming the trench is not particularly limited, and is typically formed by laser processing.

In this embodiment, at least all four sides of the internal shield parts 412 and 422 are arranged inside the sealing body 30. That is, the internal shield parts 412 and 422 are not exposed to the outside of the circuit module 100, and each side surface is covered with the sealing body 30. Thereby, deterioration of the internal shield parts 412, 422 due to changes over time can be suppressed, and the internal shield parts 412, 422 can be protected from peeling from the sealing body 30 when the circuit module 100 is handled.

Furthermore, in this embodiment, as shown in FIG. 3, the outer shield part 411 has an extension part 411a that extends further outward of the first circuit area B1 than the inner shield part 412. The extension portion 411 a is formed over a length extending from the connection region between the outer shield portion 411 and the inner shield portion 412 to the peripheral edge of the top surface 301 of the sealing body 30 .

Similarly, the outer shield part 421 has an extension part 421a that extends further outward of the second circuit area B2 than the inner shield part 422. The extension portion 421 a is formed over a length extending from the connection region between the outer shield portion 421 and the inner shield portion 422 to the peripheral edge of the top surface 301 of the sealing body 30 .

Since the external shield parts 411 and 421 have the extension parts 411a and 421a, for example, when handling the circuit module 100 (for example, when transporting or mounting it on a motherboard), external equipment can be attached to the upper surface periphery of the sealing body 30. Even if some contact objects such as Separation due to contact friction with the contact portion can be prevented as much as possible.

According to the circuit module 100 of this embodiment configured as described above, the first shield 41 covering the first circuit area B1 and the second shield 42 covering the second circuit area B2 are electrically connected to each other. Since the first circuit area B1 and the second circuit area B2 are separated from each other, mixing of signals between the first circuit area B1 and the second circuit area B2 can be suppressed. This makes it possible to prevent electrical crosstalk between the first circuit area B1 and the second circuit area B2, thereby increasing the reliability of the operation of the circuit module 100.

In particular, in the circuit module 100 of this embodiment in which a digital circuit and an analog circuit are mixed, signals are mixed from the first circuit area B1 forming the digital circuit to the second circuit area B2 forming the analog circuit. Since this can be prevented, signal processing accuracy in the second circuit area B2 can be improved.

Further, according to the present embodiment, the first conductor pattern 121 connected to the first shield 41 and the second conductor pattern 122 connected to the second shield 42 are electrically separated from each other by the first ground. Since it is connected to the wiring 131 and the second ground wiring 132, it is possible to prevent signals from being mixed between the first and second circuit regions B1 and B2 via the ground line.

[Circuit module manufacturing method]
Next, a method for manufacturing the circuit module 100 of this embodiment will be described with reference to FIGS. 4 and 5.

First, as shown in FIG. 4(a), the first mounted component 21 and the second mounted component 22 are mounted on the first circuit area B1 and the second circuit area B2 on the circuit board 10A, respectively. . In this embodiment, the circuit board 10A is an aggregate board that is an assembly of a plurality of circuit boards 10, and the circuit module 100 is produced by cutting the circuit board into individual product sizes in the final process. The mounting method for the first and second mounting components 21 and 22 is not particularly limited, and typically, a reflow soldering method is employed.

Next, as shown in FIG. 4(b), a sealing body 30 is formed on the component mounting surface B of the circuit board 10 to cover the first mounted component 21 and the second mounted component 22. There are no particular limitations on the method for forming the sealing body 30, and for example, a screen printing method, a vacuum printing method, a transfer molding method, etc. can be used.

Subsequently, as shown in FIG. 4C, trenches C for forming internal shield parts 412 and 422 are formed at predetermined positions of the sealing body 30. The trench C is formed by irradiating a laser beam toward the top surface 301 of the sealing body 30 in a direction perpendicular to the circuit board 10 . The wavelength of the laser light is not particularly limited as long as it is in a band in which the material constituting the sealing body 30 has absorption properties, and for example, an infrared laser such as a YAG laser is used. The trench C is formed directly above the first and second conductive patterns 121 and 122 with a depth that reaches the surfaces of these conductive patterns 121 and 122. In this embodiment, the trench C is formed into a rectangular ring shape corresponding to the shape of the conductor patterns 121 and 122 by scanning the laser beam.

Next, as shown in FIG. 5A, by applying a conductive material to the top surface 301 of the sealing body 30, the external shield parts 411, 421 are formed on the top surface 301 of the sealing body 30 and inside the trench C. and internal shield parts 412 and 422, respectively. The method of forming the outer shield parts 411, 421 and the inner shield parts 412, 422 is not particularly limited, and for example, a vacuum printing method is used.

Subsequently, as shown in FIG. 5B, a groove 302 is formed in the top surface 301 of the sealing body 30 to separate the external shield part 411 and the external shield part 421. This forms the first shield 41 and the second shield 42 that are separated from each other. Finally, as shown in FIG. 5(c), the circuit board 10A is cut along the dividing line D to separate into product size pieces. The cutting method is not particularly limited, and a dicer is typically used. The circuit module 100 of this embodiment is manufactured as described above.

<Second embodiment>
Next, a second embodiment of the present invention will be described.
FIG. 6 is a perspective view of the circuit module 200 according to this embodiment, and FIG. 7 is a side sectional view of the circuit module 200.
Hereinafter, configurations that are different from those in the first embodiment will be mainly described, and configurations similar to those in the first embodiment will be denoted by the same reference numerals, and the description thereof will be omitted or simplified.

The circuit module 200 of this embodiment differs from the first embodiment in the depth of the groove 303 that separates the outer shield parts 411, 421 of the first shield 41 and the second shield 42. In this embodiment, the groove portion 303 is formed with a depth that reaches from the top surface 301 of the sealing body 30 to the component mounting surface B of the circuit board 10.

The circuit module 200 of this embodiment configured as described above can also achieve the same effects as those of the first embodiment described above. According to the circuit module 200 of this embodiment, the groove portion 303 is formed deep enough to reach the component mounting surface B, so that the block of the sealing body 30 that seals the first circuit region B1 and the block of the sealing body 30 that seals the second circuit region B2 can be mechanically separated. This makes it possible to mitigate warping of the circuit module 200 caused by the difference in thermal expansion coefficient between the circuit board 10 and the sealing body 30 during reflow mounting of the circuit module 200 on the motherboard, thereby improving the mounting reliability of the circuit module 200 on the motherboard.

Note that the depth of the groove portion 303 is not limited to the depth that reaches the component mounting surface B as described above, and may be, for example, a depth that is half or more of the thickness of the sealing body 30. In this case, it is possible to reduce the warpage of the circuit module 200 due to the above-described difference in thermal expansion coefficients, and to suppress a decrease in the bending strength of the circuit module 200.

Although the embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above-described embodiments and can be modified in various ways.

For example, in the above embodiments, the circuit board 10 is configured with a wiring board such as a glass epoxy board, but the circuit board 10 may be a board including a metal core. In this case, the circuit board may be configured as a component-embedded board in which a cavity is formed in a metal core and an IC, passive components, etc. are built into the cavity. As a result, a circuit module with high strength and heat dissipation performance can be obtained, and components can be mounted in high density.

REFERENCE SIGNS LIST 10, 10A...circuit board 21...first mounted component 22...second mounted component 30...sealing body 41...first shield 42...second shield 100...circuit module 121...first conductor pattern 122...second conductor pattern 131...first ground wiring 132...second ground wiring 200...circuit module 301...top surface 302, 303...groove portion 411...external shield portion (first external shield portion)
411a, 421a...extension portion 412...inner shield portion (first inner shield portion)
421...External shield part (second external shield part)
422...Inner shield part (second inner shield part)

Claims (7)

a circuit board having a component mounting surface having a first circuit region and a second circuit region, a first conductor pattern provided on the component mounting surface and partitioning the first circuit region, and a second conductor pattern provided on the component mounting surface and partitioning the second circuit region;
a plurality of mounted components mounted on the first circuit area and the second circuit area;
a sealing body provided in the first circuit region and the second circuit region and covering the plurality of mounted components;
a first shield made of a conductive material, the first shield having a first external shield part provided on a top surface of the sealing body, and a first internal shield part connecting the first external shield part to the first conductor pattern and at least a portion of which is disposed inside the sealing body;
a second external shield part provided on a top surface of the sealing body, and a second internal shield part connecting the second external shield part to the second conductor pattern and at least a portion of which is disposed inside the sealing body, the second shield being made of a conductive material and electrically isolated from the first shield ;
The circuit board further includes a first ground wiring connected to the first conductor pattern, and a second ground wiring connected to the second conductor pattern and electrically separated from the first ground wiring.
Circuit module. The circuit module according to claim 1 ,
The first internal shield part is formed in a cylindrical shape having at least four side surfaces that hang down from the first external shield part toward the component mounting surface,
The second internal shield part is formed in a cylindrical shape having at least four side surfaces that hang down from the second external shield part toward the component mounting surface. The circuit module according to claim 2 ,
At least four sides of the first internal shield part and the second internal shield part are covered with the sealing body. A circuit module. The circuit module according to any one of claims 1 to 3 ,
The first external shield part has an extension part that extends further to the outside of the first circuit area than the first internal shield part,
The second external shield part has an extension part extending further to the outside of the second circuit area than the second inner shield part. The circuit module according to any one of claims 1 to 4 ,
The said sealing body has a groove part provided in the said top surface and which isolate|separates a said 1st external shield part and a said 2nd external shield part from each other. Circuit module. The circuit module according to claim 5 ,
The groove portion is formed with a depth that reaches the component mounting surface from the top surface. The circuit module according to any one of claims 1 to 6 ,
A circuit module in which a digital circuit is formed in the first circuit area, and an analog circuit is formed in the second circuit area.

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