TWI893545B - Electromagnetic wave transmission board and method for fabricating the same - Google Patents

Abstract

An Electromagnetic wave transmission board including a dielectric waveguide structure and two substrate integrated waveguide structures is provided. The dielectric waveguide structure includes a first dielectric material with two trenches and two second dielectric materials disposed in those trenches. The trenches are located on two opposite surfaces of the first dielectric material, and a part of the first dielectric material is located between the trenches. The dielectric constant of the first dielectric material is lower than the dielectric constant of the second dielectric materials. The dielectric waveguide structure is disposed between two substrate integrated waveguide structures, and one of the substrate integrated waveguide structures is connected to the other one of the substrate integrated waveguide structures through the part of the first dielectric material and the second dielectric materials.

Description

Radio wave transmission board and manufacturing method thereof

The present invention relates to a radio wave transmission board, and more particularly to a radio wave transmission board disposed in a circuit board.

Traditional circuit boards use metal conductors (such as copper wires) to transmit radio signals between electronic components. However, with the development of increasingly versatile electronic products (such as mobile phones), the demand for high-speed and high-frequency signal transmission is increasing. Generally speaking, the higher the speed or frequency of the signal, the greater the signal loss when transmitted through metal conductors. Therefore, using metal conductors to transmit radio signals is no longer sufficient for these electronic products.

Therefore, the present invention provides a radio wave transmission board and its manufacturing method to reduce the loss rate of signal transmission.

The present invention provides a radio wave transmission board comprising a dielectric waveguide structure and two substrate-integrated waveguide structures. The dielectric waveguide structure comprises a first dielectric material and two second dielectric materials. The first dielectric material has two grooves, one located on opposite surfaces of the first dielectric material, with a portion of the first dielectric material located between the two grooves. The second dielectric material is disposed within each groove, and the dielectric constant of the first dielectric material is smaller than that of the second dielectric material. The dielectric waveguide structure is disposed between the substrate-integrated waveguide structures, with one substrate-integrated waveguide structure connected to the other substrate-integrated waveguide structure via a portion of the first dielectric material and the second dielectric material.

In at least one embodiment of the present invention, the dielectric constant of the first dielectric material ranges from 3.0 to 3.4, and the dielectric constant of the second dielectric material ranges from 10.0 to 20.0.

In at least one embodiment of the present invention, the dielectric waveguide structure extends from one substrate-integrated waveguide structure to another substrate-integrated waveguide structure along a longitudinal axis, wherein a portion of the first dielectric material and the second dielectric material extend along the longitudinal axis.

In at least one embodiment of the present invention, each substrate-integrated waveguide structure includes a dielectric layer, two metal layers located on opposite sides of the dielectric layer, and a plurality of conductive vias disposed in the dielectric layer. One metal layer is connected to the other metal layer via the conductive vias, and the conductive vias are electrically connected to the metal layers.

In at least one embodiment of the present invention, the substrate-integrated waveguide structure is connected to the dielectric waveguide structure via a dielectric layer.

In at least one embodiment of the present invention, the material of the dielectric layer is the same as the first dielectric material.

The present invention also provides a method for manufacturing a radio wave transmission plate. The method includes providing an embedded structure comprising a first dielectric material and two second dielectric materials. A second dielectric material is disposed on opposite sides of a first dielectric material, and the dielectric constant of the first dielectric material is smaller than that of the second dielectric material. A substrate is provided, comprising a dielectric layer and two metal layers disposed on opposite sides of the dielectric layer. A portion of the substrate is removed to form an opening connecting two opposite surfaces of the substrate. A buried structure is disposed within the opening, wherein the dielectric layer of the substrate is connected to the first and second dielectric materials of the buried structure, and the second dielectric material of the buried structure is exposed on the surface of the substrate. After the buried structure is disposed within the opening, a plurality of conductive vias are formed in the substrate, wherein the metal layers are electrically connected to each other through the conductive vias, and the conductive vias are distributed at opposite ends of the buried structure.

In at least one embodiment of the present invention, providing a buried structure includes providing a dielectric substrate; providing two composite substrates, each of which includes a second dielectric material comprising a metal foil; laminating the composite substrates to opposite sides of the dielectric substrate, with the metal foils facing each other; and after laminating the composite substrates, cutting the dielectric substrate and the composite substrate along a normal to the dielectric substrate to form the buried structure.

In at least one embodiment of the present invention, the method further includes removing the metal foil of the buried structure after forming the conductive via to expose the second dielectric material of the buried structure.

In at least one embodiment of the present invention, disposing the embedded structure within the opening includes applying tape to one surface of the substrate, with the tape covering the opening; disposing the embedded structure on the tape so that the embedded structure passes through the opening; and, after disposing the embedded structure on the tape, bonding the substrate and the embedded structure.

Based on the above, the present invention utilizes the difference in dielectric constant between a first dielectric material and a second dielectric material to provide a radio signal transmission path. A portion of the first dielectric material is sandwiched between the second dielectric materials. Because the dielectric constant of the first dielectric material is smaller than that of the second dielectric material, radio signals tend to be transmitted through the portion of the first dielectric material located between the two second dielectric materials. This radio signal transmission method prevents radio signal loss due to passing through the wires, helping to reduce the loss rate of radio signal transmission.

100: Radio wave transmission board

120: Dielectric waveguide structure

122,122’: First dielectric material

122t: Groove

305f, 305s: Surface

124a, 124b: Second dielectric material

140: Substrate-integrated waveguide structure

142,305i: Dielectric layer

144,305m: Metal layer

146:Conductive via

202: Dielectric substrate

204a, 204b: Composite substrate

204c: Metal foil

204g:Resin substrate

210: Embedded structure

301,302: Bonding film

305:Substrate

305t: Opening

307: Tape

A-A, B-B: Line segment

D1: Long axis direction

N1: normal line

w: width

The present invention will be understood from the following detailed description when reviewed in conjunction with the accompanying drawings. It should be noted that many features are not drawn to scale as is standard practice in the industry. In fact, the dimensions of the various features may be arbitrarily increased or decreased for clarity of discussion.

Figure 1A shows a top view of a radio wave transmission plate according to at least one embodiment of the present invention.

Figure 1B shows a cross-sectional view of the radio wave transmission plate along line segment A-A in Figure 1A.

Figures 2A and 2B illustrate cross-sectional views of a method for manufacturing a radio wave transmission plate according to at least one embodiment of the present invention.

Figures 3A and 3B illustrate cross-sectional views of a method for manufacturing a radio wave transmission plate along line A-A in Figure 1A according to at least one embodiment of the present invention.

Figures 3C and 3D illustrate cross-sectional views of a method for manufacturing a radio wave transmission plate along line B-B in Figure 1A according to at least one embodiment of the present invention.

The present invention will be described in detail using the following embodiments. It should be noted that the following descriptions of the embodiments of the present invention are for illustrative purposes only and are not intended to be exhaustive or to limit the present invention to specific embodiments. For example, the phrase "a first feature formed on a second feature" encompasses various implementations, including both direct contact between the first and second features and additional features formed between the first and second features without direct contact. Furthermore, identical reference numbers will be used throughout the drawings and description to represent identical or similar components whenever possible.

Spatially relative terms, such as "inferior," "lower than," "beneath," "above," and related terms, are used herein to simply describe the relationship of one component or feature to another component or feature as shown in the diagram. These spatially relative terms encompass not only the orientation depicted in the diagram but also various orientations during use or operation of the device. Furthermore, when a component is rotatable (90 degrees or other angles), the spatially relative descriptors used herein should be interpreted accordingly.

Furthermore, when using terms like "approximately" or "about" to describe a number or a range of numbers, such terms are intended to encompass numbers within a reasonable range, taking into account the natural variations in manufacturing processes that are understood by those skilled in the art. Numerical ranges encompass a reasonable range encompassing the described number. For example, within +/- 10% of the described number is based on known manufacturing tolerances associated with the characteristics of the manufacturing feature. For example, a material layer having a thickness of "approximately 5 nanometers" may encompass dimensions ranging from 4.25 nanometers to 5.75 nanometers, where the manufacturing tolerances for depositing the material layer are within +/- 15%, as is known to those skilled in the art. Furthermore, this disclosure may repeat numbers and/or designations throughout the various examples. This repetition is for simplicity and clarity and is not intended to indicate a relationship between the various implementations and/or configurations discussed here.

The present invention provides a radio wave transmission plate 100. Referring to FIG. 1A , the radio wave transmission plate 100 includes a dielectric waveguide structure 120 and two substrate-integrated waveguide structures 140. Referring to FIG. 1B , the dielectric waveguide structure 120 includes a first dielectric material 122 and two second dielectric materials 124a and 124b . The first dielectric material 122 has two grooves 122t , and these two grooves 122t are located on opposite surfaces (not shown) of the first dielectric material 122 .

As shown in Figure 1B , second dielectric materials 124a and 124b are disposed within grooves 122t, respectively. A portion of the first dielectric material 122 (not labeled) resides between the grooves 122t. Specifically, the two opposing grooves 122t are completely separated, so a portion of the first dielectric material 122 resides between the bottom surfaces of the two grooves 122t, preventing the two grooves 122t from connecting. The cross-sectional view of Figure 1B shows that the dielectric waveguide structure 120 in this region forms a sandwich structure, with the first dielectric material 122 sandwiched between the two second dielectric materials 124a and 124b, and directly contacting both second dielectric materials 124a and 124b.

In particular, the dielectric constant of the first dielectric material 122 is smaller than that of the second dielectric materials 124a and 124b. For example, the dielectric constant of the first dielectric material 122 may range from 3.0 to 3.4, and may include, for example, hydrocarbon-based polymers, polyphenylene oxide (PPO), polyphenylene ether (PPE), or similar materials. On the other hand, the dielectric constant of the second dielectric materials 124a and 124b may range from 10.0 to 20.0, and may include a glass-reinforced resin (RSR) with a high dielectric constant, or similar materials. However, the dielectric constants of the first dielectric material 122 and the second dielectric materials 124a and 124b of the present invention are not limited to the aforementioned ranges.

The dielectric waveguide structure 120 is disposed between two substrate-integrated waveguide structures 140, extending from one substrate-integrated waveguide structure 140 to the other substrate-integrated waveguide structure 140 along a longitudinal direction D1. It is worth noting that the first dielectric material 122 and the second dielectric materials 124a and 124b in the dielectric waveguide structure 120 also extend along the longitudinal direction D1, and one substrate-integrated waveguide structure 140 is connected to the other substrate-integrated waveguide structure 140 via a portion of the first dielectric material 122 and the second dielectric materials 124a and 124b. In other words, in this embodiment, a portion of the first dielectric material 122 and the second dielectric materials 124a and 124b extend in the same direction, interconnecting the two substrate-integrated waveguide structures 140 in this direction.

Because the dielectric constant of the first dielectric material 122 differs from the dielectric constants of the second dielectric materials 124a and 124b, and the dielectric constant of the first dielectric material 122 is smaller than the dielectric constants of the second dielectric materials 124a and 124b, when an electromagnetic signal is transmitted along the longitudinal axis D1 through the dielectric waveguide structure 120, the electromagnetic signal is concentrated in the portion of the first dielectric material 122 between the second dielectric materials 124a and 124b.

In other words, because the first dielectric material 122 located between the second dielectric materials 124a and 124b has a lower dielectric constant (compared to the surrounding second dielectric materials 124a and 124b), radio signals tend to pass through the first dielectric material 122. Therefore, this portion of the first dielectric material 122 can serve as the primary channel for radio signals to be transmitted from one substrate-integrated waveguide structure 140 to the other substrate-integrated waveguide structure 140.

On the other hand, while the majority of the radio wave signals transmitted within the substrate-integrated waveguide structure 140 pass through the first dielectric material 122, a small portion of the radio wave signals can still be transmitted through the second dielectric materials 124a and 124b. It is worth noting that the greater the difference between the dielectric constant of the first dielectric material 122 and the dielectric constants of the second dielectric materials 124a and 124b, the higher the proportion of the radio wave signals transmitted through the first dielectric material 122. In other words, the radio wave signal transmission is more concentrated in the first dielectric material 122 between the second dielectric materials 124a and 124b, thereby reducing radio wave signal loss during the transmission process.

Substrate-integrated waveguide structure 140 includes a dielectric layer 142, two metal layers 144, and a plurality of conductive vias 146. The two metal layers 144 are located on opposite sides of dielectric layer 142, and conductive vias 146 are disposed within dielectric layer 142. Because conductive vias 146 are located along the plane taken along line B-B in Figure 1A , they are represented by dashed lines in Figure 1B . As shown in Figure 1B , one metal layer 144 is connected to the other metal layer 144 via conductive vias 146, and conductive vias 146 electrically connect both metal layers 144. The metal layers 144 and conductive vias 146 can be made of copper. Although each substrate-integrated waveguide structure 140 of this embodiment includes six conductive vias 146, and the conductive vias 146 are arranged in pairs, the distribution and number of the conductive vias 146 are not limited thereto.

It is worth noting that in this embodiment, the substrate integrated waveguide (SIW) structure 140 can be a rectangular waveguide element used in microwave antennas, thereby feeding radio wave signals into the dielectric waveguide structure 120. Furthermore, when the radio wave transmission board 100 is mounted on a circuit board (not shown), the received radio wave signal can be introduced into the dielectric waveguide structure 120 via one of the SIW structures 140 and then transmitted to the other SIW structure 140 via the dielectric waveguide structure 120.

The substrate-integrated waveguide structure 140 is connected to the dielectric waveguide structure 120 via a dielectric layer 142. Specifically, the dielectric layer 142 of the substrate-integrated waveguide structure 140 is directly connected to opposite ends of the dielectric waveguide structure 120. In this embodiment, the dielectric layer 142 is made of the same material as the first dielectric material 122, i.e., the dielectric constant of the dielectric layer 142 may range from 3.0 to 3.4, and may include, for example, an alkyl polymer, polyoxyethylene, polyphenylene oxide, or a similar dielectric bonding material.

The present invention provides a method for manufacturing a radio wave transmission plate. Taking radio wave transmission plate 100 as an example, this manufacturing method may include several steps as shown in Figures 2A-2B and 3A-3D. First, an embedded structure 210 (shown in Figure 2B) is provided. The steps for forming embedded structure 210 are described in detail in Figures 2A-2B. As shown in Figure 2A, a dielectric substrate 202 and two composite substrates 204a and 204b are provided. Composite substrates 204a and 204b are then laminated to opposite sides of dielectric substrate 202 using heat-pressing. The dielectric substrate 202 may be made of, for example, a hydrocarbon-based resin substrate, and its dielectric constant may range from 3.0 to 3.4.

In particular, the thickness of composite substrate 204a (and composite substrate 204b) can range from 0.13 mm to 0.5 mm, for example, 0.5 mm, and each can include a double-layer metal foil 204c and a resin substrate 204g. Composite substrates 204a and 204b can be copper clad laminates (CCLs), so metal foil 204c can be copper foil. Specifically, the two layers of metal foil 204c are located on opposite sides of the resin substrate 204g.

In this embodiment, one layer of metal foil 204c can be removed by etching or polishing to form the composite substrate 204a shown in FIG2A , which includes only the metal foil 204c. The composite substrate 204a and the resin substrate 204g of 204b are bonded to the dielectric substrate 202 facing each other. That is, the metal foil 204c of the composite substrate 204a and the metal foil 204c of the composite substrate 204b are disposed opposite each other. In some embodiments, the resin substrate 204g can include materials such as fiberglass, and the dielectric constant of the resin substrate 204g can range from 10.0 to 20.0.

Referring to Figures 2A and 2B , after bonding the composite substrates 204a and 204b, the dielectric substrate 202 and the composite substrates 204a and 204b can be cut along a normal line N1 of the dielectric substrate 202 by machining (e.g., CNC machining) or laser cutting to form a buried structure 210. The buried structure 210 includes a first dielectric material 122′ and two second dielectric materials 124a and 124b, respectively, with the second dielectric materials 124a and 124b located on opposite sides of the first dielectric material 122′. Please refer to Figures 2A and 2B together. The width w of the embedded structure 210 in this embodiment can range from 1.27 mm to 2.54 mm, for example, 2 mm. However, the width w of the embedded structure 210 in the present invention is not limited to the above range.

On the other hand, referring to FIG. 3A , a substrate 305 is provided. This substrate 305 includes a dielectric layer 305i and two metal layers 305m, one located on opposite sides of the dielectric layer 305i. The dielectric layer 305i can be made of the same material as the first dielectric material 122′, while the metal layer 305m can be made of copper. Specifically, the substrate 305 can be formed by laminating multiple layers of bonding films (prepreg) using thermal compression. For example, in this embodiment, two layers of bonding adhesive sheets 301 are stacked on top of each other, and two layers of bonding adhesive sheets 302 including metal layers 305m are stacked on the outer sides of the bonding adhesive sheets 301. These layers are then bonded together by heat and pressure to form a substrate 305.

Next, referring to FIG. 3B , a portion of the substrate 305 is removed to form an opening 305t . This opening 305t connects the opposing surfaces 305f and 305s of the substrate 305. After the opening 305t is formed, the embedded structure 210 is disposed within the opening 305t . In this embodiment, the step of disposing the embedded structure 210 within the opening 305t includes attaching an adhesive tape 307 (e.g., polyethylene terephthalate tape) to the surface 305s of the substrate 305, with the tape 307 covering the opening 305t. The embedded structure 210 is then disposed on the tape 307 such that the embedded structure 210 passes through the opening 305t . After the embedded structure 210 is placed on the tape 307, the substrate 305 and the embedded structure 210 can be bonded together using heat and pressure lamination. The tape 307 is then removed.

It is worth noting that after bonding the substrate 305 and the embedded structure 210, the dielectric layer 305i of the substrate 305 is connected to the first dielectric material 122' and the second dielectric materials 124a and 124b of the embedded structure 210. Furthermore, the surfaces 305f and 305s of the substrate 305 expose the second dielectric materials 124a and 124b of the embedded structure 210, respectively (when ignoring the metal foil 204c). In other words, the embedded structure 210 is disposed within the opening 305t such that the first dielectric material 122' is sandwiched between the second dielectric materials 124a and 124b, with the second dielectric materials 124a and 124b facing outward from the substrate 305.

Referring to Figure 3C , after the embedded structure 210 is disposed within the opening 305t, a plurality of conductive vias 146 are formed in the substrate 305. The two metal layers 305m of the substrate 305 are electrically connected via the conductive vias 146, which are distributed on opposite sides of the embedded structure 210. Specifically, some conductive vias 146 are located in the left substrate 305 (i.e., on the left side of the embedded structure 210), while others are located in the right substrate 305 (i.e., on the right side of the embedded structure 210).

The step of forming conductive vias 146 may include: forming a plurality of through-holes (not shown) in substrate 305 connecting surfaces 305f and 305s by mechanical drilling. Then, a metal layer (e.g., a copper layer) is deposited on the inner walls of the through-holes by, for example, plating through hole (PTH) to form conductive vias 146.

Referring to FIG. 3D , after forming the conductive via 146, the metal foil 204c of the embedded structure 210 can be removed by etching to expose the second dielectric materials 124a and 124b of the embedded structure 210. Furthermore, in this embodiment, after forming the conductive via 146, the metal layer 305m of the substrate 305 can also be patterned by etching to form the metal layer 144 shown in FIG. 1A .

In summary, at least one embodiment of the present invention utilizes the difference in dielectric constants between a first dielectric material and a second dielectric material to provide a radio signal transmission path. A portion of the first dielectric material is sandwiched between the second dielectric materials, forming a sandwich-like embedded structure. Because the dielectric constant of the first dielectric material is smaller than that of the second dielectric material, radio signals tend to propagate through the portion of the first dielectric material located between the two second dielectric materials. This method of forming a radio signal transmission path based on the difference in dielectric constants prevents radio signal loss caused by passing through metal conductors (e.g., copper conductors), thereby helping to reduce radio signal loss.

Although the embodiments of the present invention have been disclosed above, they are not intended to limit the embodiments of the present invention. Anyone with ordinary skill in the art may make minor changes and modifications without departing from the spirit and scope of the embodiments of the present invention. Therefore, the scope of protection of the embodiments of the present invention shall be determined by the scope of the attached patent application.

100: Radio wave transmission board

120: Dielectric waveguide structure

122: First dielectric material

122t: Groove

124a, 124b: Second dielectric material

140: Substrate-integrated waveguide structure

142: Dielectric layer

144: Metal layer

146:Conductive via

D1: Long axis direction

Claims (9)

A radio wave transmission board includes: a dielectric waveguide structure comprising: a first dielectric material having two grooves, the grooves being located on opposite surfaces of the first dielectric material, wherein a portion of the first dielectric material is located between the grooves; two second dielectric materials disposed within the grooves, wherein the dielectric constant of the first dielectric material is smaller than the dielectric constant of the second dielectric material; and two substrate-integrated waveguide structures, wherein the dielectric waveguide structure is disposed between the substrate-integrated waveguide structures. , and one of the substrate-integrated waveguide structures is connected to the other of the substrate-integrated waveguide structures through the portion of the first dielectric material and the second dielectric material; wherein each of the substrate-integrated waveguide structures includes: a dielectric layer; two metal layers, respectively located on opposite sides of the dielectric layer; and a plurality of conductive vias, disposed in the dielectric layer, and one of the metal layers is connected to the other of the metal layers through the conductive vias, wherein the conductive vias are electrically connected to the metal layers. The radio wave transmission plate of claim 1, wherein the dielectric constant of the first dielectric material is in the range of 3.0 to 3.4, and the dielectric constant of the second dielectric material is in the range of 10.0 to 20.0. The radio wave transmission board according to claim 1, wherein the dielectric waveguide structure extends from one of the substrate-integrated waveguide structures to the other substrate-integrated waveguide structure along a longitudinal axis, wherein the portion of the first dielectric material and the second dielectric material extend along the longitudinal axis. The radio wave transmission board as claimed in claim 3, wherein the substrate-integrated waveguide structure is connected to the dielectric waveguide structure through the dielectric layer. The radio wave transmission board as described in claim 3, wherein the material of the dielectric layer is the same as the first dielectric material. A method for manufacturing a radio wave transmission plate comprises: providing an embedded structure, the embedded structure comprising: a first dielectric material; and two second dielectric materials, wherein the second dielectric materials are located on opposite sides of the first dielectric material, and the dielectric constant of the first dielectric material is smaller than the dielectric constant of the second dielectric material; providing a substrate, the substrate comprising: a dielectric layer; and two metal layers, located on opposite sides of the dielectric layer; removing a portion of the substrate to form an opening, wherein the opening is connected to The substrate has two opposing surfaces; the embedded structure is disposed in the opening, wherein the dielectric layer of the substrate is connected to the first dielectric material and the second dielectric material of the embedded structure, and the second dielectric material of the embedded structure is exposed on the surfaces of the substrate; and after the embedded structure is disposed in the opening, a plurality of conductive vias are formed in the substrate, wherein the metal layers are electrically connected to each other through the conductive vias, and the conductive vias are distributed at opposite ends of the embedded structure. A method as described in claim 6, wherein providing the embedded structure includes: providing a dielectric substrate; providing two composite substrates, each of the composite substrates comprising a metal foil; laminating the composite substrates on opposite sides of the dielectric substrate, respectively, and arranging the metal foils back to back to each other; and after laminating the composite substrates, cutting the dielectric substrate and the composite substrate along the normal of the dielectric substrate to form the embedded structure. The method as described in claim 7 further includes: after forming the conductive through hole, removing the metal foil of the buried structure to expose the second dielectric material of the buried structure. A method as described in claim 6, wherein arranging the embedded structure in the opening includes: attaching a tape on one of the surfaces of the substrate, and the tape covers the opening; arranging the embedded structure on the tape so that the embedded structure passes through the opening; and after arranging the embedded structure on the tape, joining the substrate and the embedded structure.