This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2019-128659, filed on Jul. 10, 2019, the entire contents of which are incorporated herein by reference.
The disclosed technique is related to an electronic module and an electronic device.
As techniques related to an electronic module in which a plurality of heat-generating components are mounted over a board, the following techniques are known. For example, an electronic apparatus has been described. This electronic apparatus includes a heat dissipation member that is disposed in a housing of the electronic device and that disperses and dissipates heat generated by a plurality of heat generating elements mounted over a board in the housing. The heat dissipation member is disposed so as to face the board, includes separator portions that thermally separate the heat generating elements, and is formed of a resin molded material containing carbon fiber having electrical conductivity and thermal conductivity.
Also, in a known hybrid integrated circuit, a plurality of individual components are mounted over a board and airtightly sealed by a cap. The individual components are separated into groups of predetermined numbers of the individual components and airtightly sealed by the cap. For this, the cap is partitioned by a plurality of partitioning projection walls into a plurality of space portions.
Examples of the related art include Japanese Laid-open Patent Publication No. 2004-207661 and Japanese Unexamined Utility Model Registration Application Publication No. 60-88551.
According to an aspect of the embodiments, an electronic module includes: a plurality of heat generating members provided over a first surface of a board; a frame joined to the first surface of the board and provided between the plurality of heat generating members that are arranged; and a lid configured to cover the first surface of the board and thermally coupled to each of the plurality of heat generating members.
The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention.
As a technique of next-generation wireless communication, there is a known technique in which a plurality of antennas are disposed over a board, and a beam-shaped radio wave is radiated toward wireless terminals by controlling the phases of signals transmitted from the antennas. With this technique, high-speed, large-capacity communication may be realized.
Signal processing circuits such as phase shifters and amplifiers are mounted over the board so as to correspond to the respective antennas. For example, when a fan-out wafer level package (FOWLP) is used as a package for a signal processing circuit, transmission loss of the signals may be reduced, and further, high-density mounting may be achieved. An electronic module that includes antennas and electronic components including a signal processing circuits over a board as described above preferably includes a heat dissipation mechanism that radiates heat generated by the electronic components to the outside so as to avoid damage caused by the heat generated by the electronic components.
The heat dissipation mechanism is configured by, for example, joining a lid formed of a material having a high thermal conductivity to the electronic components that are heat sources. In order to ensure heat dissipation properties, it is preferable that the lid and the electronic components be in close contact with each other, and it is preferable that a material having a comparatively high thermal conductivity such as solder and thermal grease be used in joining the lid and the electronic component.
In an electronic module configured as described above, when the amount of heat generation of the electronic components mounted over the board increases, the board may be deformed (bent) by the difference in thermal expansion coefficient between the electronic components and the board, thereby breaking the joining between the lid and the electronic components. As a result, the thermal dissipation function of the lid is not necessarily effectively produced, and accordingly, the electronic components may be damaged by the heat generation.
Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, substantially the same or equal elements or parts are denoted by the same reference numerals.
The board 10 is formed of an insulator such as, for example, a glass epoxy resin. The electronic components 20 are mounted over the first main surface S1 of the board 10 so as to form a matrix along the sides of the rectangular board 10. As illustrated in
As illustrated in
Each of the electronic components 20 includes a signal processing circuit that processes signals transmitted and received through a corresponding one of the antennas 30. The signal processing circuit may include, for example, a transmission circuit and a reception circuit, and the transmission circuit and the reception circuit may include, for example, a phase shifter and an amplifier. Each of the electronic components 20 is, for example, in the form of fan-out wafer level package (FOWLP) and is coupled to the electrodes 13 formed over the first main surface S1 of the board 10 through a plurality of solder bumps 21 formed over a surface joined to the board 10. The signal processing circuit processes signals of comparatively high frequencies, and the electronic component 20 generates a comparatively high heat during operation. The electronic component 20 is an example of a heat generating member in the disclosed technique.
The frame 40 having a grid shape is provided over the first main surface S1 of the board 10 along the electronic components 20 that are arranged. For example, the frame 40 is a grid-shaped member that extends through spaces between the electronic components 20 adjacent to each other in the longitudinal direction and the transverse direction so as to separate the electronic components 20 from each other, Preferably, the frame 40 has a rigidity higher than the rigidity of the board 10. Thus, the frame 40 may function as a reinforcing member that suppresses deformation (bending) of the board 10 caused by heat generation of the electronic components 20. Preferably, the Young's modulus of the frame 40 is, for example, 100 GPa or more. Preferably, the thermal expansion coefficient of the frame 40 is, for example, 20×10−6/K or smaller. When the Young's modulus and the thermal expansion coefficient of the frame 40 are in the above-described ranges, the effect of suppressing the deformation of the board 10 by the frame 40 may be increased. Preferably, as the material of the frame 40, for example, metal such as stainless steel (SUS), copper, tungsten, or molybdenum or a ceramic such as alumina, zirconia, or silicon carbide may be used. Alternatively, diamond or sapphire may be used.
As illustrated in
When the frame 40 is formed by combining a plurality of bar-shaped members with each other as described above, the manufacture of the frame 40 is facilitated compared to the case where the frame 40 is formed as a single unit. Furthermore, the size and number of squares of the grid of the frame 40 may be flexibly varied.
As illustrated in
The lid 50 covers the first main surface S1 of the board 10. The lid 50 has a recess on a side facing the board 10. The electronic components 20 are housed in a space defined by the recess of the lid 50 and the first main surface S1 of the board 10. Preferably, the lid 50 is formed of a material having a comparatively high thermal conductivity such as silver, copper, aluminum, or alumina.
Each of the electronic components 20 is joined to a surface S3 of the lid 50 facing the board 10 with a joining material 60 having a comparatively high thermal conductivity interposed therebetween. For example, each of the electronic components 20 is thermally coupled to the lid 50. Preferably, as the joining material 60, materials having a comparatively high thermal conductivity such as, for example, solder and thermal grease are used. An outer peripheral portion of the lid 50 is joined to the first main surface S1 of the board 10 with a joining material 61 interposed therebetween. A conductor pattern (not illustrated) used for joining to the lid 50 may be formed over the first main surface S1 of the board 10 at a position corresponding to the outer peripheral portion of the lid 50. In this case, solder may be used as the joining material 61. Alternatively, a resin adhesive may be used as the joining material 61.
Hereinafter, a method of manufacturing the electronic module 1 is described.
First, the board 10 is prepared. The electrodes 13 (see
Next, the electronic components 20 are mounted over the first main surface S1 of the board 10 (
Next, the frame 40 is mounted over the first main surface S1 of the board 10 (
Next, the joining material 60 including materials having a comparatively high thermal conductivity such as solder and thermal grease is formed over surfaces of the electronic components 20 opposite the surface joined to the board 10. Then, the lid 50 is mounted over the first main surface S1 of the board 10 (
In contrast, in the electronic module 1 according to the embodiment of the disclosed technique, the grid-shaped frame 40 along the electronic components 20 that are arranged is joined to the first main surface S1 of the board 10. The frame 40 may function as the reinforcing member that increases the rigidity of the board 10 to suppress the deformation (bending) of the board 10 caused by the heat generation of the electronic components 20. Thus, the joining between the lid 50 and the electronic components 20 may be maintained, the thermal dissipation function of the lid 50 may be effectively produced, and the risk of damaging the electronic components 20 may be reduced. The frame 40 is joined not only to the board 10 but also to the lid 50. Thus, the reinforcing function of the frame 40 may be further improved, and accordingly, the effect of suppressing the deformation of the board 10 may be increased. The frame 40 has a grid shape along the electronic components 20 that are arranged. Thus, the entire region of the board 10 may be uniformly reinforced.
The effect of suppressing the deformation of the board 10 by using the frame 40 was verified by a simulation.
In the model according to Example 1 including the frame 40M formed of stainless steel, the deformation amount of the board 10M is reduced by 0.2 mm compared to the model according to the comparative example without the frame. In the model according to Example 2 including the frame 40M formed of alumina, the deformation amount of the board 10M is reduced by 0.9 mm compared to the model according to the comparative example without the frame.
R=(ΔL2−ΔL1)/ΔL2 (1)
For example, when the deformation amount reduction rate R is a positive value, it is indicated that the deformation amount of the board 10M is smaller than that of the comparative example. When the deformation amount reduction rate R is a negative value, it is indicated that the deformation amount of the board 10M is greater than that of the comparative example.
As illustrated in
The electronic module 1A according to the second embodiment includes the board 10 having a hexagonal external shape. The frame 40 includes portions 40C and multiple annular portions 40D, 40E. The portions 40C radially extend from the center toward the vertices of the board 10. The annular portions 40D, 10E are centered at the center of the board 10 and disposed parallel to the sides of the board 10. For example, the frame 40 is in the form of a mesh shape in the electronic module 1A. The electronic components 20 are disposed in regions separated by the portions 40C, 40D, 40E of the frame 40. The orientation of the electronic components 20 may vary from region to region.
In the electronic module 1A according to the present embodiment, similarly to the electronic module 1 according to the first embodiment, deformation of the board 10 caused by the heat generation of the electronic component 20 as the heat generating member may be suppressed. Although the board 10 having a hexagonal external shape is described as an example for the present embodiment, the external shape of the board 10 may be any polygon having five or more angles (vertices).
The electronic device 2 is included in a communication device that performs wireless communication and includes a housing 70, a baseband board 80, and an electronic module 1. As the electronic module 1, the electronic module 1 according to the first embodiment of the disclosed technique or the electronic module 1A according to the second embodiment of the disclosed technique may be used. The baseband board 80 is housed in the housing 70. The electronic module 1 is attached to a surface of the housing 70 such that the antennas 30 face outward.
As illustrated in
The RF unit 100 is a block that processes analog signals of a frequency band of an electromagnetic wave transmitted and received through an antenna 120. The RF unit includes a transmission circuit 101 and a reception circuit 102. The functions of the RF unit 100 are implemented in the electronic module 1. For example, the functions of the transmission circuit 101 and the reception circuit 102 included in the RF unit 100 are implemented in the electronic components 20 included in the electronic module 1, and the antenna 120 is realized by the antennas 30 included in the electronic module 1.
In the electronic device 2 according to the embodiments of the disclosed technique, deformation of the board 10 included in the electronic module 1 may be suppressed, thereby reducing the risk of damaging the electronic components 20. Thus, the reliability of the electronic device 2 may be improved.
All examples and conditional language provided herein are intended for the pedagogical purposes of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although one or more embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.
Number | Date | Country | Kind |
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2019-128659 | Jul 2019 | JP | national |