This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2016-100428, filed on May 19, 2016, the entire contents of which are incorporated herein by reference.
The embodiments discussed herein are related to a wireless communication module and a method of manufacturing wireless communication module.
In recent years, a wireless communication module has been used in a wireless communication device, a radar device, and an imaging device using a high-frequency electromagnetic wave (high frequency signal) in, for example, a millimeter wave band or higher. The wireless communication module includes, for example, a waveguide horn antenna (horn antenna) and a semiconductor chip (Monolithic Microwave Integrated Circuit (MMIC)).
For example, a horn antenna used in a wireless communication device or the like transmits and receives a high frequency signal, includes a truncated pyramidal (conical) metal waveguide whose port is tapered in a manner to be gradually widened, has good beam pattern controllability, and is capable of earning a high antenna gain. Note that the term “high frequency signal” herein includes, for example, a signal of a millimeter wave (wavelength from 1 mm to 10 mm: frequency from 30 GHz to 300 GHz), a sub-millimeter wave (1 mm or less: 300 GHz or more), and a terahertz wave (30 μm to 3 mm: 0.1 THz to 10 THz).
In a wireless communication module, for example, a high frequency signal transmitted and received by a horn antenna is processed by a semiconductor chip (MMIC). When a high frequency signal is input, for example, a propagation mode of the high frequency signal is converted from a signal for a horn antenna (waveguide) to a signal for a planar transmission line (microstrip line) and is input to a semiconductor chip. In addition, when a high frequency signal is output, for example, a signal from the semiconductor chip via the planar transmission line is converted into a propagation mode for a high frequency signal and is output from the horn antenna. In this manner, a wireless communication module (extremely high frequency band module) includes, mounted thereon, a horn antenna, an antenna conversion unit, a substrate for signal transmission and a semiconductor chip, for example.
In addition, it has been recently contemplated that a wireless communication module is mounted on a compact portable terminal such as a smartphone and a wearable device. However, since the wireless communication module includes a horn antenna, size reduction, in particular, thickness reduction is desired.
Specifically, for example, a wireless communication module with a thickness (height) of 1 mm or less is desired to be mounted on a smartphone or the like without deteriorating design flexibility. The problem in size is present not only when mounting a wireless communication module on a compact portable terminal such as a smartphone but also when applying a wireless communication module to various devices.
Incidentally, in the past, there have been proposed various wireless communication modules to which a waveguide horn antenna is applied.
Patent Document 1: Japanese Laid-open Patent Publication No. 2014-179935
Patent Document 2: Japanese Laid-open Patent Publication No. 2013-247494
Patent Document 3: Japanese Laid-open Patent Publication No. 1998(H10)-224141
Patent Document 4: Japanese Laid-open Patent Publication No. 2002-353729
According to an aspect of the embodiments, there is provided a wireless communication module includes a horn antenna and a semiconductor chip, and the horn antenna and the semiconductor chip are integrally formed by a mold resin and are connected through a transmission line.
The horn antenna includes an open end provided on a longitudinal end face of the wireless communication module; an antenna conversion unit located on an opposite side of the open end and connected with the semiconductor chip through the transmission line; and a side face part whose shape is varied in a thickness direction of the wireless communication module in a manner such that an opening area is widened from the antenna conversion unit toward the open end.
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.
First, before describing embodiments of a wireless communication module and a method of manufacturing the wireless communication module, an example of a wireless communication module and a problem thereof will be described with reference to
As illustrated in
Inside the module casing 101, a cavity 102 is formed in which a transmission line substrate 106 and a semiconductor chip 103 mounted thereon are provided. In addition, at an end of the transmission line substrate 106, a transmission line (microstrip line) 107 is formed, where a conversion unit for mutually converting between a waveguide mode of the horn antenna 105 and a transmission mode of the microstrip line 107 is provided.
In the wireless communication module 100, as illustrated in
By the way, data transmission using radio frequency has been recently used in various fields. For example, a short-range radio communication technology such as Near Field Communication (NFC) has spread widely and there are a variety of uses thereof. One of conceivable technical developments in the future is to improve a transmission rate and enable, for example, data transfer of a large volume of contents such as high-definition video. Examples of application of such a technique include a download system that allows a user to instantaneously acquire data by holding a user's own information terminal over a server arranged in a station kiosk, a convenience store and the like for distributing information such as movies, music, sports and news.
Conceivable examples of the user's information terminal include a compact portable terminal such as a smartphone and a wearable device. However, these compact portable terminals may impose strict restrictions on size of an electronic component to be mounted. Specifically, the restriction on size is also present in a wireless communication module. As for “thinness”, a wireless communication module is desired to be less than 1 mm in height, for example. Note that the restriction on size (height and thickness) is not limitedly present only when mounting a wireless communication module on a compact portable terminal such as a smartphone, but also present when applying a wireless communication module to various devices.
In other words, in the wireless communication module 100 (module casing 101) illustrated in
In the following, embodiments of a wireless communication module and a method of manufacturing the wireless communication module are described in detail with reference to the accompanying drawings.
In
As illustrated in
The horn antenna 15 includes the open end 19 provided on a longitudinal end face of the wireless communication module 1, and the antenna conversion unit 14 located on an opposite side of the open end 19 and connected with the semiconductor chip 13 through the microstrip line 17. Further, the horn antenna 15 includes the side face parts 15b and 15c whose shape is varied in a thickness direction of the wireless communication module 1 in a manner such that an opening area is widened from the antenna conversion unit 14 toward the open end 19.
The open end 19 of the horn antenna 15 can be formed in, for example, a rectangular shape. In other words, a side face part (side face parts 15d and 15e in
Further, an upper face (first side face) 15b, a lower face (second side face) 15c, a left face (third side face 15d), and a right face (fourth side face 15e) of the dielectric material 15a in the horn antenna 15 are preferably metalized (coated with metal) except for the antenna conversion unit 14 and the open end 19. However, even without metal coating on all of the first to fourth side faces, the horn antenna 15 functions enough as an antenna owing to a dielectric confinement effect, for example.
Inside the horn antenna 15, the dielectric material 15a having a large permittivity (relative permittivity) is filled, and a thickness of the wireless communication module 1 is suppressed to be 1 mm or less, for example. Note that alumina ceramics, high-resistivity silicon, quartz, sapphire, an organic material such as High Density Polyethylene (HDPE) and the like can be used as the dielectric material 15a, for example.
In addition, the open end 19 of the horn antenna 15 is a face parallel with the longitudinal end face of the wireless communication module 1, and the anti-reflective coating layer 19a is provided to the open end 19. Note that a material of the anti-reflective coating layer 19a has a permittivity intermediate between a permittivity of air through which a high frequency signal that the wireless communication module 1 uses is transmitted and the permittivity of the dielectric material 15a filled inside the horn antenna 15, for example. Specifically, Parylene-C, Parylene-D, Silicon Dioxide (SiO2), Graphene, and the like can be used as a material of the anti-reflective coating layer 19a.
The antenna conversion unit 14 includes, for example, a dielectric waveguide where the upper face 15b and the lower face 15c of the dielectric material 15a in the horn antenna 15 are metalized, and the microstrip line 17 that sets a ground potential GND to the same plane as the metalized upper face 15b. In addition, the semiconductor chip 13 can be electrically connected above the antenna conversion unit 14 of the horn antenna 15 through a via (a connection via 18 in
In this manner, the wireless communication module according to the first example becomes able to be formed thin (for example, as thin as 1 mm or less) while suppressing a signal loss between the horn antenna 15 and the semiconductor chip 13. In addition, since the horn antenna 15 can be formed as an end-fire antenna in which a feed node is arranged on a proximal end face portion of the semiconductor chip 13 or in the vicinity thereof, it is possible to earn an antenna gain in a lateral direction (longitudinal direction) without increasing a thickness. Further, by filling the dielectric material 15a inside the horn antenna 15, it is possible to implement a compact, yet high-gain antenna owing to a wavelength shortening effect.
Phase shifts in an aperture (open end 19) of the optimum horn are a ⅜ wavelength and a ¼ wavelength in H-plane (Z=0 plane) and E-plane (Y=0 plane), respectively, and a size of the optimum horn (lengths of a and b) can be expressed by the following equations, where λ depicts a wavelength.
a=(3Lhλ)1/2
b=(2Leλ)1/2
Based on the equations above, a relation between the height-direction size b and the flare length L in E-plane of the optimum horn in consideration of the wavelength in the dielectric is illustrated in
In
As illustrated by the characteristic curved line C1 in
In contrast, as illustrated by the characteristic curved line C3 in
Note that the horn antenna 15, although being different from the optimum horn, has the open end 19 whose width a (width direction)× height b (thickness direction) is 2 mm×0.5 mm, has a length L of L=3 mm, and has the dielectric material 15a made of alumina ceramics. In addition, the horn antenna 15 has metal layers only on the upper face 15b and the lower face 15c thereof, with the left face 15d and the right face 15e being in contact with the mold resin 11. Further, a high frequency signal having a wavelength of 1 mm, in other words, having a frequency of 300 GHz is used.
As illustrated in
As illustrated in
Note that a shape (cross-sectional shape) of the hole in the GND metal around the connection via 18 is not limited to a square of 0.4 mm×0.4 mm, but may be a circle or the like, for example. However, the hole is preferably formed as a hole of a size equal to or less than half a wavelength of a high frequency signal to be applied. In other words, since a wavelength of a high frequency signal to be applied in the simulation is 1 mm, a square hole having a cross-sectional shape of 0.4 mm×0.4 mm is applied as the connection via 18. In addition, a portion of the alumina waveguide 15 (a portion corresponding to the antenna conversion unit 14 of the horn antenna 15 in which the dielectric material 15a is filled) in
As illustrated in
As described above, the wireless communication module 1 according to the first example is able to be manufactured with low loss and good reproducibility, since the horn antenna 15 and the semiconductor chip (MMIC) 13 are connected through the microstrip line 17 (RDL). The wireless communication module 1 according to the first example is able to be formed thin while suppressing a signal loss between the horn antenna and the semiconductor chip. The configurations and advantageous effects described above in detail will be the same in a second example described below.
In other words, the aperture of the open end 19 is cut along a face forming the angle α with a longitudinal end face of the wireless communication module 1′, so that the upper face 15b and the lower face 15c of the horn antenna 15 are formed symmetric to each other. In other words, the horn antenna 15 is so configured as to be capable of symmetrically controlling antenna directivity by aligning the shape thereof. Note that it is possible to cut the open end 19 at a predetermined angle by using, for example, a grinding machine. In addition, it is needless to say that the anti-reflective coating layer 19a can be provided to the open end 19 of the horn antenna 15 in the same manner as in the first example described with reference to
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 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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2016-100428 | May 2016 | JP | national |