WO2021066365A1

WO2021066365A1 - Waveguide integrated substrate and fabricating method thereof

Info

Publication number: WO2021066365A1
Application number: PCT/KR2020/012672
Authority: WO
Inventors: Byoung-Gwan KANG; Sungtek Kahng; Sang-Tae Kim; Hyung-Soo Moon; Changhyeong LEE
Original assignee: Incheon National University Research & Business Foundation; Corning Incorporated
Priority date: 2019-10-02
Filing date: 2020-09-18
Publication date: 2021-04-08
Also published as: KR20210039569A

Abstract

Provided are a substrate integrated waveguide and a manufacturing method thereof. A base substrate extends in a propagation direction of an electromagnetic wave signal and formed from a glass material. A plurality of vias formed from metal extend through the base substrate from an upper surface to a lower surface, aligned in the propagation direction of the electromagnetic wave signal. An upper electric conductor is formed on the upper surface of the base substrate and connected to the plurality of vias. A lower electric conductor is formed on the lower surface of the base substrate and connected to the upper electric conductor through the plurality of vias. A pitch of adjacent vias is two to eight times as great as a diameter of the via. The thickness of the glass substrate and the diameters and the pitch of vias are optimized for the glass substrate.

Description

WAVEGUIDE INTEGRATED SUBSTRATE AND FABRICATING METHOD THEREOF

The present disclosure relates to a substrate integrated waveguide and a manufacturing method thereof. More particularly, the present disclosure relates to a substrate integrated waveguide and a manufacturing method thereof able to provide a substrate-integrated waveguide (SIW) optimized for a substrate formed from glass, in which the thickness of the glass substrate, the diameters of vias formed in the glass substrate, and pitches between adjacent vias are optimized for the glass substrate in order to reduce intersection-loss and obtain cost efficiency.

It may be difficult to use existing substrates, such as FR4 substrates, for the fabrication of radio frequency (RF) components used at ultrahigh frequencies (mmWave range) of tens of GHz or higher in fifth generation (5G) mobile communication systems, due to, for example, dielectric loss and surface quality issues in such RF component substrates. Here, materials considered for RF component substrates used in the mmWave range are, for example, Teflon and glass. Such materials have advantages, such as low dielectric loss, superior surface qualities, and precision machinability.

A substrate-integrated waveguide (SIW) structure is used as a means for transmitting electromagnetic waves, since such an SIW structure can obtain low insertion loss and a high quality factor by preventing radiation loss of electromagnetic waves using a via wall.

In addition, in a case in which glass is used as a material for a substrate for a substrate-integrated waveguide, vias smaller than those of existing materials can be formed more precisely and with minimal errors. Thus, it is expected that RF components having further reduced insertion loss and superior quality may be fabricated. However, to date, there have been substantially no cases in which RF components are fabricated using glass as a material for substrate-integrated waveguides. Accordingly, there have been no cases in which design optimization is performed to determine the most efficient size (diameter) and shape of vias optimized for a glass substrate, the number of the vias to be aligned in the glass substrate, pitches between adjacent vias, the thickness of the glass substrate, the thickness of a conductor, and the like.

Various aspects of the present disclosure provide a substrate integrated waveguide and a manufacturing method thereof able to provide a substrate-integrated waveguide (SIW) optimized for a substrate formed from glass, in which the thickness of the glass substrate, the diameters of vias formed in the glass substrate, and pitches between adjacent vias are optimized for the glass substrate in order to reduce intersection-loss and obtain high cost efficiency.

According to an aspect of the present disclosure, a substrate integrated waveguide may include: a base substrate extending in a propagation direction of an electromagnetic wave signal and formed from a glass material; a plurality of vias formed to extend through the base substrate from an upper surface to a lower surface, aligned in the propagation direction of the electromagnetic wave signal, and formed from metal; an upper electric conductor formed on the upper surface of the base substrate and connected to the plurality of vias; and a lower electric conductor formed on the lower surface of the base substrate and connected to the upper electric conductor through the plurality of vias, wherein a pitch of vias, among the plurality of vias, adjacent to each other, is two to eight times as great as a diameter of the via.

Here, the via may have the diameter of about 30 μm to 200 μm.

The base substrate may have a thickness of about 0.5 mm to about 2.0 mm.

The via may have a cylindrical, conical, or hourglass shape.

The upper electric conductor may have a thickness of about 100 nm to 10 μm.

The upper electric conductor may have a patterned shape, and the lower electric conductor may cover the entire lower surface of the base substrate.

According to an aspect of the present disclosure, a substrate integrated waveguide may include: preparing a base substrate extending in a propagation direction of an electromagnetic wave signal and formed from a glass material; forming a plurality of via holes aligned in the propagation direction of the electromagnetic wave signal by perforating the base substrate from an upper surface to a lower surface; plating the upper and lower surfaces of the base substrate with metal to fill the plurality of via holes; with the metal and patterning a plated layer formed on the upper surface of the base substrate, wherein in the forming, the plurality of via holes are formed by perforating the base substrate such that a pitch of via holes, among the plurality of via holes, adjacent to each other, is two to eight times as great as a diameter of the via.

In the forming, the plurality of via holes may be formed in the base substrate using a laser.

In the forming, the plurality of via holes may be formed in the base substrate using an etching process.

In the forming, the plurality of via holes may be formed to have a diameter (D) of about 30 μm to about 200 μm.

In the forming, the plurality of via holes may be formed to have a cylindrical, conical, or hourglass shape.

In the preparing, the base substrate having a thickness of about 0.5 mm to 2. 0mm may be prepared.

In the plating, the plated layer may be formed to have a thickness of about 100 nm to 10 μm.

According to the present disclosure, a substrate formed from glass is used, the thickness of the glass substrate optimized to be within a range of 0.5 mm to 2.0 mm, and the size of vias formed in the glass substrate is adjusted such that the diameters (D) of the vias range from 30 μm to 200 μm, and the pitches (P) between the vias to be aligned in the glass substrate in a propagation direction of an electromagnetic wave signal are adjusted such that the pitches (P) between adjacent vias range from 2 to 8 times the diameters (D) of the vias. Accordingly, insertion loss can be reduced.

In addition, according to the present disclosure, the vias may be formed to have an optimized shape in view of cost reductions, and the conductors may be provided on the top and bottom surfaces of the glass substrate by plating to be as thin as possible, as long as the conductors are connected to the vias. In this manner, high cost efficiency can be obtained.

That is, according to the disclosure, the substrate-integrated waveguide (SIW) structure optimized for a substrate formed from a glass material can be provided.

The methods and apparatuses of the present disclosure have other features and advantages that will be apparent from or that are set forth in greater detail in the accompanying drawings, the disclosures of which are incorporated herein, and in the following Detailed Description, which together serve to explain certain principles of the present disclosure.

FIG. 1 is a plan view illustrating a substrate integrated waveguide according to an exemplary embodiment;

FIG. 2 is a cross-sectional view illustrating a substrate integrated waveguide according to an exemplary embodiment;

FIG. 3 is a graph illustrating simulation results illustrating insertion losses for non-alkali glass substrates and fused silica glass substrates, in which diameters of vias are 100 μm and pitches between adjacent vias are a variety of values, the simulation being performed in the 24 to 32 GHz frequency range;

FIG. 4 is a graph illustrating simulation results illustrating insertion losses for non-alkali glass substrates and fused silica glass substrates, in which diameters of vias are 200 μm and pitches between adjacent vias are a variety of values, the simulation being performed in the 24 to 32 GHz frequency range;

FIG. 5 is a graph illustrating simulation results illustrating insertion losses for non-alkali glass substrates and fused silica glass substrates, in which diameters of vias were 300 μm and pitches between adjacent vias had a variety of values, the simulation being performed in the 24 to 32 GHz frequency range using electromagnetic wave modeling software;

FIG. 6 illustrates simulation results illustrating electromagnetic field distribution and leakage along an SIW transmission line for a non-alkali glass substrate and a fused silica glass substrate, in which the diameters of vias were 100 μm and pitches between adjacent vias were 2,000 μm, the simulation being performed in the 24 to 32 GHz frequency range;

FIG. 7 is a schematic view illustrating vias having a variety of shapes;

FIG. 8 is a graph illustrating a simulation result illustrating insertion losses for a non-alkali glass substrate, in which vias had a cylindrical shape, a conical shape, and an hourglass shape (with diameters of 100 μm), as illustrated in FIG. 7, and pitches between adjacent vias were 200 μm, the simulation being performed in the 24 to 32GHz frequency range;

FIG. 9 is a schematic view illustrating glass substrates having a variety of thicknesses;

FIG. 10 is a graph illustrating simulation results illustrating insertion losses for the non-alkali glass substrates having the thicknesses (0.25mm and 0.5mm), as illustrated in FIG. 9, the simulation being performed in the 24 to 32GHz frequency range, in which the length of a transmission line was 30 mm in (a) of FIG. 10, and the length of a transmission line was 60 mm in (b) of FIG. 10;

FIG. 11 is a schematic view illustrating non-alkali glass substrates including conductors having a variety of thicknesses;

FIG. 12 is a graph illustrating a simulation result for non-alkali glass substrates including the conductors having a variety of thicknesses, the simulation being performed in the 24 to 32GHz frequency range;

FIG. 13 is a schematic view illustrating a configuration in which a substrate integrated waveguide according to an embodiment is disposed; and

FIG. 14 is a schematic view illustrating an arrangement of a substrate integrated waveguide according to an embodiment.

Hereinafter, a substrate integrated waveguide and a manufacturing method thereof according to embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

In the following description, detailed descriptions of known functions and components incorporated into the present disclosure will be omitted in the case in which the subject matter of the present disclosure is rendered unclear by the inclusion thereof.

FIG. 1 is a plan view illustrating a substrate integrated waveguide according to an exemplary embodiment, and FIG. 2 is a cross-sectional view illustrating a substrate integrated waveguide according to an exemplary embodiment.

As illustrated in FIGS. 1 and 2, a substrate integrated waveguide 100 is a substrate used for the fabrication of wireless communication components, e.g. radio frequency (RF) antennas, and includes a base substrate 110, a plurality of vias 120, an upper conductor 131, and a lower conductor 132.

The base substrate 110 extends in a propagation direction of an electromagnetic wave signal. According to an embodiment, the base substrate 110 is formed from a glass material. Glass is suitable as a material for the substrate integrated waveguide 100 for wireless communication components in the mmWave range, due to advantages thereof, such as low dielectric loss, superior surface qualities, and precision machinability. In contrast, related-art substrates, such as FR4 substrate, are not suitable to be used for the fabrication of wireless communication components in the mmWave range, due to, for example, dielectric loss and surface quality issues in the substrates.

According to an embodiment, the thickness of the base substrate 110 may range from 0.5 mm to 2.0 mm. Here, the thickness of the base substrate 110 is set to be within a range in which insertion loss can be minimized when the base substrate 110 is formed from a glass material. In addition, the insertion loss is greater with increases in the length of the base substrate 110 extending in the propagation direction of the electromagnetic wave signal. In a case in which the length of the base substrate 110 is the same, the difference in the insertion loss between a case in which the thickness of the base substrate is within the above-mentioned range and a case in which the thickness of the base substrate is outside of the above-mentioned range tends to increase with increases in the length of the base substrate 110.

That is, according to an embodiment, the thickness of the base substrate 110 is determined to be within a range of 0.5mm to 2.0mm in order to provide a substrate-integrated waveguide (SIW) structure optimized for the base substrate 110 formed from glass.

Although the glass material of the base substrate 110 will be represented as being non-alkali glass or fused silica glass hereinafter, the material of base substrate 110 is not necessarily limited to such a glass composition.

The vias 120 are formed to extend through the base substrate 110 from the upper surface to the lower surface (in the drawing). In an embodiment, the vias 120 are metal columns formed from metal, filling via holes provided in the base substrate 110.

The vias 120 are provided as a plurality of vias aligned in the propagation direction of an electromagnetic signal. Although a structure in which the plurality of vias 120 are aligned in two rows according to the exemplary embodiment is illustrated, this is illustrative only. The plurality of vias 120 may be aligned in a variety of patterns, depending on the pattern of an RF antenna formed by the upper conductor 131.

According to an embodiment, the diameters D of the vias 120 formed in the base substrate 110 and the pitches P between the adjacent vias 120 are determined to be within ranges optimized for the base substrate 110 formed from glass. That is, according to the embodiment, the diameters D of the vias 120 and the pitches P between the adjacent vias 120 are determined to be within ranges in which the insertion loss of the substrate integrated waveguide 100, based on the base substrate 110 formed from glass, can be minimized.

According to an embodiment, the pitches P between the adjacent vias 120 are determined to be 2 to 8 times the diameters D of the vias 120. Here, the base substrate 110 may be finely perforated using, for example, a laser device. Accordingly, the vias 120 having diameters D ranging from 30 μm to 200 μm may be formed. The insertion loss associated with the diameters D of the vias 120 and the pitches P between the adjacent vias 120 will be described in more detail hereinafter.

As illustrated in FIG. 7, the vias 120 may have a variety of shapes, such as a cylindrical shape, a conical shape, and an hourglass shape, as long as there is no effect on insertion loss. That is, in consideration of cost efficiency, the vias 120 may be formed to have a suitable shape selected from among the above-mentioned shapes that have no effect on the insertion loss.

The upper conductor 131 is formed on the upper surface of the base substrate 110. Here, the upper conductor 131 may be formed on the upper surface of the base substrate 110 to form an RF antenna pattern. The upper conductor 131 is connected to the plurality of vias 120 extending through the base substrate 110 from the upper surface to the lower surface.

According to an embodiment, the thickness of the upper conductor 131 may range from 100 nm to 10 μm. Here, the influence of the thickness of the upper conductor 131 to the insertion loss is insignificant. Thus, in consideration of cost efficiency, the upper conductor 131 may be formed to be as thin as possible within the above-mentioned thickness range, as long as the upper conductor 131 can be connected to the plurality of vias 120.

The lower conductor 132 is formed on the lower surface of the base substrate 110. The lower conductor 132 is connected to the upper conductor 131 via the plurality of vias 120 formed from metal. The lower conductor 132 is formed on the entire surface of the base substrate 110 to form a ground layer of the substrate integrated waveguide 100.

Hereinafter, simulation results illustrating characteristics of a structure optimized for the above-described base substrate formed from glass will be described.

First, FIG. 3 and Table 1 below represent simulation results illustrating insertion losses of non-alkali glass substrates (EXG) and fused silica glass substrates, in which diameters D of vias were 100 μm and pitches P between adjacent vias had a variety of values, the simulation being performed in the 24 to 32 GHz frequency range using electromagnetic wave modeling software (CST Studio).

P/D	IL@Avg. (EXG)	P/D	IL@Avg. (Fused)
2	-1.6332	2	-0.28701
4	-1.62353	4	-0.29405
6	-1.62358	6	-0.29712
8	-1.60618	8	-0.30407
10	-1.66539	10	-0.37771
12	-2.1852	12	-0.65437
14	-1.66841	14	-0.3839
16	-1.77723	16	-0.44389
18	-1.72522	18	-0.37706
20	-2.72318	20	-0.93192
22	N/A	22	-1.09266
24	N/A	24	-2.5782

As will be apparent from FIG. 3 and Table 1, in all of the non-alkali glass substrates (EXG) and the fused silica glass substrates, if the diameters D of the vias were 100 μm, there was substantially no difference in insertion loss in a case in which the pitches P between the adjacent vias were 2 to 8 times the diameters of the vias.

FIG. 4 and Table 2 below represent simulation results illustrating insertion losses of non-alkali glass substrates (EXG) and fused silica glass substrates, in which diameters D of vias were 200 μm and pitches P between adjacent vias had a variety of values, the simulation being performed in the 24 to 32 GHz frequency range using electromagnetic wave modeling software (CST Studio).

P/D	IL@Avg. (EXG)	P/D	IL@Avg. (Fused)
2	-1.7028	2	-0.30245
4	-1.65967	4	-0.28993
6	-1.63998	6	-0.27917
8	-1.63998	8	-0.33043
10	-2.20298	10	-0.61482
12	-5.68342	12	-0.60204
14	N/A	14	-4.94926

As will be apparent from FIG. 4 and Table 2, in all of the non-alkali glass substrates (EXG) and the fused silica glass substrates, if the diameters D of the vias were 200 μm, there was substantially no difference in insertion loss in a case in which the pitches P between the adjacent vias were 2 to 8 times the diameters of the vias, as in the case in which the diameters D of the vias were 100 μm.

FIG. 5 and Table 3 below represent simulation results illustrating insertion losses of non-alkali glass substrates (EXG) and fused silica glass substrates, in which diameters D of vias were 300 μm and pitches P between adjacent vias had a variety of values, the simulation being performed in the 24 to 32 GHz frequency range using electromagnetic wave modeling software (CST Studio).

P/D	IL@Avg. (EXG)	P/D	IL@Avg. (Fused)
2	-1.68349	2	-0.36213
4	-1.8451	4	-0.43884
6	-3.58539	6	-0.80808
8	-11.3898	8	-2.02451
10	-11.0652	10	-7.61489

As will be apparent from FIG. 5 and Table 3, in the non-alkali glass substrate (EXG) and the fused silica glass substrate, if the diameters D of the vias were 300 μm, insertion loss was significantly increased in a case in which the pitches P between the adjacent vias were 2 or more times the diameters of the vias.

FIG. 6 illustrates simulation results illustrating electromagnetic field distribution and leakage along an SIW transmission line in a non-alkali glass substrate (EXG) and a fused silica glass substrate, in which the diameters D of vias were 100 μm and pitches between adjacent vias were 2,000 μm, the simulation being performed in the 24 to 32 GHz frequency range.

As will be apparent from the simulation results of FIG. 6, both the non-alkali glass substrate (EXG) and the fused silica glass substrate had substantially no radiation loss in the direction of an electromagnetic signal if the pitches P between the adjacent vias are 2 times the diameters D of the vias. In contrast, it was found that, if the pitches P between the adjacent vias were 20 times the diameters D of the vias, radiation loss in the direction of an electromagnetic signal was significant and the intensity of the electromagnetic signal was also reduced. Here, it can be seen that insertion loss was significant.

FIG. 7 is a schematic view illustrating vias having a variety of shapes, and FIG. 8 is a graph illustrating a simulation result illustrating insertion losses of a non-alkali glass substrate, in which vias had a cylindrical shape, a conical shape, and an hourglass shape (with diameters of 100 μm), as illustrated in FIG. 7, and pitches between adjacent vias were 200 μm, the simulation being performed in the 24 to 32GHz frequency range.

As will be apparent from the result of the simulation illustrated in FIG. 8, if diameters D of the vias were 100 μm and the pitches P between the adjacent vias were 200 μm, i.e. P/D was 2, the formation of the vias had substantially no effect on insertion loss. Here, it can be seen that the shape of the vias is not required to be specifically considered in design optimization.

FIG. 9 is a schematic view illustrating glass substrates having a variety of thicknesses, and FIG. 10 is a graph illustrating simulation results illustrating insertion losses of the non-alkali glass substrates having the thicknesses (0.25mm and 0.5mm), as illustrated in FIG. 9, the simulation being performed in the 24 to 32GHz frequency range. FIG. 10 illustrates a result in which the length of a transmission line was 30 mm ((a) of FIG. 10), and a result in which the length of a transmission line was 60 mm ((b) of FIG. 10).

As will be apparent from the simulation results illustrated in FIG. 10, the insertion loss of the 0.5 mm thick non-alkali glass substrate was lower than that of the 0.25mm thick non-alkali glass substrate. It was also found that the difference in the insertion loss increased with increases in the length of a transmission line.

FIG. 11 is a schematic view illustrating non-alkali glass substrates including conductors having a variety of thicknesses, and FIG. 12 is a graph illustrating a simulation result of the non-alkali glass substrates including the conductors having a variety of thicknesses, the simulation being performed in the 24 to 32GHz frequency range.

As will be apparent from the simulation results illustrated in FIG. 12, there was substantially no difference in insertion loss when conductors were formed from copper (Cu) on the non-alkali glass substrate at different thicknesses, i.e. there was no difference in insertion loss between a case in which the thickness of the conductor was 2 μm and a case in which the thickness of the conductor was 0.1 μm.

The above-described simulation results may be summarized as follows.

First, it can be appreciated that, if the diameters D of the vias range from 100 μm to 200 μm, there is no significant difference in performance even when the pitches P between the adjacent vias are increased to be 8 times the diameters D of the vias, rather than 2 times the diameters of the vias.

Second, it can be appreciated that, if the diameters D of the vias are 300 μm or greater, the ratio of the pitches P between the vias with respect to the diameters D of the vias needs to be maintained to be as small as possible, in particular, 2 or less.

Third, it can be appreciated that the thickness of the substrate from among the thickness of the substrate, the shape of the vias, and the thickness of the conductor has most significant effect on the insertion loss. The shape of the vias and the thickness of the conductor have substantially no significant effect on the insertion loss.

Accordingly, the range of design optimization may be suggested as follows.

That is, in a case in which a base substrate formed from glass is used, it is preferable that the diameters D of the vias is small, and the pitches P between the vias may be 8 times the diameters D of the vias when the diameters D of the vias are 100 μm.

In addition, in a case in which the base substrate formed from glass is used, the conductor may be formed as thin as possible, as long as the vias can be connected. The shape of the vias may be determined to reduce costs as low as possible. The thickness of the base substrate formed from glass may be thicker than a typical substrate having a thickness of 0.25 mm. For example, the thickness of the base substrate formed from glass may be 0.5 mm.

Hereinafter, a method of manufacturing a substrate integrated waveguide according to an exemplary embodiment will be described. In the description of the manufacturing method, components will be designated by reference numerals shown in FIGS. 1 and 2.

The method of manufacturing a substrate integrated waveguide according to the exemplary embodiment includes a base substrate preparation step, a via hole formation step, a plating step, and a patterning step.

First, in the base substrate preparation step, a base substrate 110 extending in a propagation direction of an electromagnetic wave is prepared. In the base substrate preparation step, the base substrate 110 having a thickness of 0.5 mm to 2.0 mm may be prepared.

Afterwards, in the via hole formation step, a plurality of via holes are formed in the base substrate 110 to extend through the base substrate 110 from the upper surface thereof to the lower surface thereof, or vice versa. Accordingly, in the via hole formation step, the plurality of via holes aligned in the propagation direction of an electromagnetic wave may be formed in the base substrate 110. In the via hole formation step, the plurality of via holes are formed in the base substrate 110 by perforating the base substrate 110 such that pitches P between adjacent via holes are 2 to 8 times the diameters D of the via holes. In the via hole formation step, the via holes may be formed such that the diameters D range from 30 μm to 200 μm. For example, if the diameters D of the via holes are determined to be 100 μm, distances between the adjacent via holes may be adjusted such that the pitches P between the adjacent via holes are from 200 μm to 800 μm. In addition, if the diameters D of the via holes are 200 μm, the distances between the adjacent via holes may be adjusted such that the pitches P between the adjacent via holes are 400 μm to 1600 μm.

In the via hole formation step, the plurality of via holes may be formed in the base substrate 110 using laser beams. For example, in the via hole formation step, the plurality of via holes may be formed in the base substrate 110 using ultraviolet (UV) radiation, Pico laser beams, or the like. In addition, in the via hole formation step, a variety of laser devices, such as a CO ₂ laser, may be used. Alternatively, in the via hole formation step, the plurality of via holes may be formed in the base substrate 110 by etching.

That is, in the via hole formation step, the plurality of via holes may be formed in the base substrate 110 by a relatively inexpensive method, in view of cost efficiency.

In addition, in the via hole formation step, the via holes may be formed to have a shape, such as a cylindrical shape, a conical shape, or an hourglass shape. In the via hole formation step, the via holes may be formed to have a shape by which the via holes can be easily formed at low cost, since the shape of vias 120 formed by filling the via holes with a metal has an insignificant effect on insertion loss.

Subsequently, in the plating step, a plated layer, provided to form the upper conductor 131 and the lower conductor 132, is formed by plating the upper surface and the lower surface of the base substrate 110 with a plating material, for example, copper (Cu). Here, in the plating step, plating is performed to completely fill the plurality of via holes with Cu in order to form the plurality of vias 120 of Cu.

In the plating step, the plated layer may be formed to be as thin as possible, as long as the plated layer can be connected to the vias 120, in consideration of cost efficiency. For example, in the plating step, the base substrate 110 may be plated with Cu, such that the thickness of the plated layer ranges from 100 nm to 10 μm. However, this is only an example, and the plated layer having the above-described thickness may be formed by plating the base substrate 110 with a variety of metals, such as Ag, as well as Cu.

Finally, in the patterning step, the plated layer formed on the upper surface of the base substrate 110 is patterned. In the patterning step, an upper conductor 131 having an RF antenna pattern is formed by patterning the plated layer.

FIG. 13 is a schematic view illustrating a configuration in which a substrate integrated waveguide according to an embodiment is disposed, and FIG. 14 is a schematic view illustrating an arrangement of a substrate integrated waveguide according to an embodiment.

One of biggest issues in the mobile device industry, in which smartphones among cellphones are typical products, is the design of antennas. A mobile device has a variety of antennas disposed in upper and lower portions of the interior thereof. Such antennas may include not only telecommunication antennas for third generation (3G) cellular network technology and long term evolution (LTE) technology, but also a variety of other antennas for Bluetooth communication, near field communication (NFC), radio frequency identification (RFID) signals, global positioning system (GPS) signals, and the like. As antennas having various shapes must be added to smartphones having gradually increasing levels of performance, a space for antenna circuits on a printed circuit board (PCB), a reduction of electromagnetic interference (EMI) noise, and greater battery capacity have been required. In addition, since a greater number of circuits and components are disposed inside of a mobile device, the available internal space of the mobile device tends to decrease. The designing of antennas is becoming a more difficult and labor-intensive operation that must be performed in every model change. In addition, in preparation for the 5G communications era, future mobile devices must be additionally provided with a 5G antenna used in a frequency range of tens of GHz while all existing antennas are still provided.

The design of a 5G antenna may be problematic since it requires a pattern in which the 5G antenna having a greater number of channels than those of an existing 3G antenna must be disposed in top, bottom, left, and right blocks. With increases in power consumption due to the greater number of channels being used, the capacity of a battery must be increased. This is a difficult problem to be solved.

To solve this problem, a design able to obtain an efficient configuration and arrangement for a 5G antenna and increase the capacity of a battery must be realized using a block assembly configuration, fundamentally allowing various shapes of antennas to be integrated. In addition, the 5G antenna requires optimal characteristics of permittivity and a loss tangent due to communications at a high transmission and reception frequency of tens of GHz, compared to 3G antennas. However, it is difficult to satisfy such characteristics.

To solve the above-described issues in mobile devices for ultrahigh radio frequency (RF) communications, some embodiments separately use a thin piece of fusion glass having a low loss tangent and superior surface roughness as a 5G antenna substrate by separating the space for provision of an antenna from the existing battery and substrate space. This is intended to 1) efficiently obtain a space inside of a mobile device by using a high-characteristic integrated antenna in a block assembly configuration for the antenna, and 2) improve limited characteristics of an existing substrate, such as an FR4 substrate, due to the introduction of the 5G antenna. Mobile device antennas for various types of communications, such as 3G/LTE, Bluetooth, NFC, RFID, GPS, digital multimedia broadcasting (DMB), and frequency modulation (FM) broadcasting, as well as 5G communications, may be integrated into the thin glass substrate to be inserted into a mobile device. This can decouple the design and mounting space of antennas from the mobile device, thereby overcoming the problem of insufficient mounting space for antennas and the difficulty of designing. In addition, this can satisfy the requirement for increased capacitance and size of the battery, and contribute to solving the low loss tangent and surface roughness issues in 5G substrates.

In some embodiments, as illustrated in FIG. 13, a thin glass substrate on which antennas dedicated to a mobile device are fabricated may be disposed on the inside of a rear cover. In the related art, antennas are arranged in the top and bottom portions of a device. In contrast, in the present disclosure, antennas are disposed directly on the inside of a rear cover, such that a space in which antennas are disposed is separated from the remaining components.

A plurality of through-holes may be formed in the thin glass substrate, metal antenna patterns may be formed on the thin glass substrate, and some antennas may be connected to a separate antenna control chip.

In such embodiments, the most important factor is that the flexibility of the design of the mobile device is increased, since the antenna design is separated from the internal design of the mobile device. Since the antenna is inserted into the mobile device by forming a macroscopic pattern on the separate antenna substrate and attaching the antenna substrate to the mobile device, for mobile device designing engineers, the problem of having to perform difficult operations of designing patterns in response to every model change in order to pack antennas into the limited upper and lower spaces in which the battery and the substrate are located in the related art is reduced. Accordingly, the rate of development of mobile devices can be advantageously increased.

In relation to the above-described effect, the technical concept of the disclosure can solve the limited capacity problem of a related-art battery and provide sufficient space, and thereby, can deal with increased power consumption due to improved performance.

In addition, due to replacement of the separate antenna substrate in the related art with the glass substrate, loss tangents in a high frequency range (e.g. 28 GHz) for 5G communications or the like can be significantly reduced, compared to the related-art FR4 substrate. Since surface roughness is improved due to the use of fusion glass, it is possible to effectively respond to a skin effect, by which surface quality becomes more important in a higher frequency range. (The skin effect is a phenomenon in which, in a higher frequency range, current more tends to only flow through the surface or an area adjacent to the surface, so that signal quality is more influenced by surface roughness.)

In addition, the area of the plane on which antenna patterns can be formed is increased to be greater than that of the upper and lower portions of the mobile device of the related art. Since the surface roughness can be improved and the signal loss tangent can be reduced, the transmission/reception sensitivity of voice/data signals of the mobile device can be improved.

The foregoing descriptions of specific exemplary embodiments of the present disclosure have been presented with respect to the drawings and are not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed herein, and many modifications and variations would obviously be possible for a person having ordinary skill in the art in light of the above teachings.

It is intended, therefore, that the scope of the present disclosure not be limited to the foregoing embodiments, but be defined by the Claims appended hereto and their equivalents.

Description of Reference Numerals of Drawings

100: substrate integrated waveguide 110: base substrate

120: via 131: upper conductor

132: lower conductor

Claims

A substrate integrated waveguide comprising:

a base substrate formed from a glass material, the base substrate comprising an upper and lower surfaces and a length along which an electromagnetic wave signal is to be propagated, and extending along the length;

an upper electric conductor formed on the upper surface of the base substrate; and

a lower electric conductor formed on the lower surface of the base substrate,

a plurality of vias formed from metal, the plurality of vias disposed along the length such that a pitch (P) of the plurality of vias is two to eight times as large as a diameter (D) of the plurality of vias, each of the plurality of vias extending through the base substrate to connect the upper electric conductor and the lower electric conductor with each other.
The substrate integrated waveguide according to claim 1, wherein the diameter of the plurality of vias is about 30 μm to 200 μm.
The substrate integrated waveguide according to claim 1, wherein the base substrate has a thickness of about 0.5 mm to about 2.0 mm.
The substrate integrated waveguide according to claim 1, wherein the plurality of vias have a cylindrical, conical, or hourglass shape.
The substrate integrated waveguide according to claim 1, wherein the upper electric conductor has a thickness of about 100 nm to 10 μm.
The substrate integrated waveguide according to claim 1, wherein the upper electric conductor has a patterned shape, and the lower electric conductor covers the entire lower surface of the base substrate.
A method of manufacturing a substrate integrated waveguide, comprising:

preparing a base substrate formed from glass, the base substrate comprising an upper and lower surfaces and a length along which an electromagnetic wave signal is to be propagated, and extending along the length;

forming a plurality of via holes along the length such that a pitch (P) of the plurality of via holes is two to eight times as large as a diameter (D) of the plurality of via holes by perforating the base substrate from the upper surface to the lower surface;

coating the upper and lower surfaces of the base substrate with metal such that the plurality of via holes are filled with the metal and layers of the metal are formed on the upper and lower surfaces of the base substrate; and

patterning the layer formed on the upper surface of the base substrate.
The method according to Claim 7, wherein in the forming, the plurality of via holes are formed in the base substrate using a laser.
The method according to Claim 7, wherein in the forming, the plurality of via holes are formed in the base substrate using an etching process.
The method according to Claim 7, wherein in the forming, the plurality of via holes are formed to have a diameter (D) of about 30 μm to about 200 μm.
The method according to Claim 7, wherein in the forming, the plurality of via holes are formed to have a cylindrical, conical, or hourglass shape.
The method according to Claim 7, wherein in the preparing, the base substrate having a thickness of about 0.5 mm to 2.0 mm is prepared.
The method according to Claim 7, wherein in the coating, the layer formed on the upper surface of the base substrate is formed to have a thickness of about 100 nm to 10 μm.