JP7522438B2 - Waveguide component and method for manufacturing the same - Patents.com - Google Patents

Description

The present invention relates to a waveguide component and a method for manufacturing a waveguide component.

A waveguide is a structure that transmits waves along a given path. Waveguides connect components in a circuit, such as filters, amplifiers, multiplexers, etc.

For example, Patent Document 1 describes a waveguide fabricated using a 3D printer. Also, for example, Patent Document 2 describes a waveguide assembly in which multiple additively manufactured waveguides are assembled.

International Publication No. 2017/203568 Special table 2019-527989 publication

The waveguide described in Patent Document 1 is intended to prevent bending due to its own weight, and is a heavy waveguide made of metal. The waveguides described in Patent Document 2 are each molded as a single piece. As a result, the conductor surrounding the waveguide cannot be made uniform, and sufficient transmission characteristics cannot be obtained.

The present invention was made in consideration of the above circumstances, and aims to provide a lightweight waveguide component with excellent transmission characteristics.

The inventors have discovered that by molding two or more resin parts and coating their surfaces with a highly conductive and smooth coating film, it is possible to obtain a lightweight waveguide component with excellent transmission characteristics. In order to solve the above problems, the present invention provides the following means.

(1) A waveguide component according to a first aspect comprises a first part and a second part which are joined together, at least one of the first part and the second part has a groove on the joining surface which becomes a waveguide when joined together, the first part and the second part each comprise a resin part containing a resin and a coating film which covers the resin part and has a higher conductivity than the resin, and in the groove, the arithmetic surface roughness (Ra) of the coating film is smaller than the arithmetic surface roughness (Ra) of the resin part.

(2) In the waveguide component according to the above aspect, the arithmetic surface roughness (Ra) of the coating film may be less than 20 μm, and the arithmetic surface roughness (Ra) of the resin part may be 20 μm or more.

(3) In the waveguide component according to the above aspect, the coating film may be a metal plating film.

(4) In the waveguide component according to the above aspect, when the first part and the second part are joined, the waveguide component may have flanges at both ends in the transmission direction, and the flanges may be divided across the joining surface.

(5) In the waveguide component according to the above aspect, the density of the outer surface of the resin part may be higher than the density of the interior.

(6) In the waveguide component according to the above aspect, the shape of a cross section obtained by cutting the waveguide along a plane perpendicular to the transmission direction is rectangular, the waveguide has two first surfaces through which a first current having a component in the transmission direction flows, and two second surfaces through which a second current perpendicular to the transmission direction flows, and the junction surface may intersect with the first surfaces.

(7) The method for manufacturing a waveguide component according to the second aspect includes a first step of producing two or more resin parts using additive manufacturing technology, a second step of coating the outer surface of each of the resin parts with a material having a higher conductivity than the resin material constituting the resin parts, and a third step of joining the resin parts coated with the coating film to form a waveguide on the joining surface.

(8) In the method for manufacturing a waveguide component according to the above aspect, the additive manufacturing technique in the first step may be a powder bed fusion process.

(9) In the method for manufacturing a waveguide component according to the above aspect, in the second step, an electroless plating process may be performed, followed by an electrolytic plating process.

The waveguide components described above have excellent transmission characteristics and are lightweight.

FIG. 1 is a perspective view of a waveguide component according to an embodiment of the present invention. FIG. 2 is an exploded view of the waveguide component according to the present embodiment. FIG. 2 is a cross-sectional view of a waveguide component according to the present embodiment. FIG. 2 is a side view of the waveguide component according to the present embodiment. FIG. 4 is a diagram showing a surface current flowing through a waveguide according to the present embodiment. FIG. 11 is a perspective view of another example of a waveguide according to the present embodiment. FIG. 1 is a perspective view of a portion of a filter using a waveguide according to an embodiment of the present invention. FIG. 1 is a diagram showing transmission characteristics of Example 1 and Comparative Example 1. FIG. 13 is a diagram showing the characteristics of the filters of Example 2 and Comparative Example 2.

The waveguide component according to this embodiment will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may show characteristic parts in an enlarged scale for the sake of convenience in order to make the features easier to understand, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and may be modified as appropriate without departing from the spirit of the description.

First, let us define the directions. The direction in which the waveguide component 100 described later extends is the x direction. The x direction coincides with the signal transmission direction, for example. The direction perpendicular to the x direction and perpendicular to the joint surface between the first component 10 and the second component 20 described later is the y direction. The direction perpendicular to the x direction and the y direction is the z direction.

Figure 1 is a perspective view of a waveguide component 100 according to this embodiment. The waveguide component 100 is one of the elements that make up a waveguide. The waveguide component 100 has a first part 10 and a second part 20, and has a waveguide Wg inside. The first part 10 and the second part 20 are joined together. The first part 10 and the second part 20 are joined together, for example, by screwing, gluing, welding, etc.

The waveguide component 100 has a main part M and a flange F when the first part 10 and the second part 20 are joined. The main part M is a part that extends in the transmission direction of the waveguide component 100. The flanges F are at both ends of the waveguide component 100 in the transmission direction and are parts that extend in a direction intersecting the main part M. The flanges F extend, for example, in the yz direction. The flanges F are responsible for connection to another waveguide component 100.

Figure 2 is an exploded view of the waveguide component 100 according to this embodiment. In Figure 2, the first part 10 and the second part 20 are exploded so that the joint surfaces between them are exposed. The first part 10 has, for example, a groove 10a. The second part 20 has, for example, a groove 20a. The grooves 10a and 20a form the waveguide Wg. Figure 2 shows an example in which the grooves 10a and 20a are formed in both the first part 10 and the second part 20, but the groove 10a or groove 20a may be formed in only one of them.

Figure 3 is a cross-sectional view of the waveguide component 100 according to this embodiment. Figure 3 is a cross-section of the waveguide component 100 shown in Figure 1 taken along the yz direction. The first part 10 and the second part 20 are joined together with their joint surfaces facing each other to form the waveguide component 100. The joint surfaces extend along the xz plane. The opening between the first part 10 and the second part 20 forms the waveguide Wg.

The waveguide Wg transmits high-frequency signals. The waveguide Wg transmits, for example, microwaves or millimeter waves. The shape of the yz cross section of the waveguide Wg is, for example, rectangular. The shape of the yz cross section of the waveguide Wg may be circular, elliptical, or the like. The waveguide Wg is surrounded by a conductive coating film C.

The first component 10 and the second component 20 each have a resin component R and a coating film C. The coating film C covers the resin component R.

The resin part R includes a resin. There is no particular restriction on the resin that constitutes the resin part R, so long as it can form a coating film on the outer surface. The resin part R is, for example, nylon 11 or nylon 12. The shape of the resin part R is not a restriction, and any shape can be produced. The resin part R is produced by additive manufacturing technology, details of which will be described later. The resin part R is tougher and less likely to break than resin members produced by stereolithography. For example, resin members produced by stereolithography are prone to cracking when fastened by screws, which poses yield issues, but nylon 11 and nylon 12 are tougher and do not crack when fastened by screws.

The density of the resin part R is, for example, 0.7 g/cm ³ or more.

The resin part R may also have different densities on its outer surface and inside. For example, the density of the outer surface of the resin part R may be higher than the density of its inside. By lowering the density of the inside of the resin part R, the conductive tube component 100 becomes lighter.

The coating film C has a higher electrical conductivity than the resin constituting the resin part R. The electrical conductivity of the coating film C is, for example, 1.43×10 ⁷ S/m or more. The coating film C is, for example, a metal plating film. The coating film C is, for example, an element or an alloy containing Cu, Ni, Ag, or Au. Cu, Ni, and Au have better corrosion resistance than Ag and are therefore suitable as the coating film C.

The thickness of the coating film C is, for example, 1 μm or more and 100 μm or less, preferably 10 μm or more and 50 μm or less, and more preferably 20 μm or more and 30 μm or less.

In the grooves 10a, 20a of the first part 10 and the second part 20, the arithmetic surface roughness (Ra) of the coating film C is smaller than the arithmetic surface roughness (Ra) of the resin part R. In other words, the surfaces of the grooves of the first part 10 and the second part 20 after coating with the coating film C are flatter than the surfaces of the grooves of the resin part R before coating with the coating film C. The arithmetic surface roughness (Ra) of the coating film C is, for example, less than 20 μm. The arithmetic surface roughness (Ra) of the resin part R is, for example, 20 μm or more.

Figure 4 is a side view of the waveguide component 100 according to this embodiment. Figure 4 is a view of the waveguide component 100 as viewed from the x direction, and a view of the flange F as viewed from the x direction. The flange F in the waveguide component 100 is composed of a semicircular plate of the first part 10 and a semicircular plate of the second part 20. That is, the first part 10 and the second part 20 each have a main part that forms the waveguide Wg and a semicircular plate that forms a flange. The flange F can be divided, for example, across the joint surface between the first part 10 and the second part 20.

Figure 5 is a diagram of the waveguide Wg according to this embodiment. In Figure 5, the surface current flowing through the waveguide Wg is illustrated as a current line. The current lines of the surface current flowing through the waveguide Wg are divided into a first current line Ia and a second current line Ib. The first current line Ia represents a surface current that has a component in the transmission direction (x direction). The first current line Ia extends over the first surface S1 of the waveguide Wg. The second current line Ib represents a surface current that is perpendicular to the transmission direction. The second current line Ib extends over the second surface S2 of the waveguide Wg.

The joint surface between the first component 10 and the second component 20 is provided, for example, at a position intersecting with the first surface S1. For example, the joint surface passes through the midpoint of the long side of the waveguide Wg in the yz cross section and is perpendicular to the long side. By providing the joint surface at a position that does not interrupt the surface current of the waveguide Wg, the transmission characteristics of the waveguide component 100 are improved.

Next, a method for manufacturing the waveguide component 100 according to this embodiment will be described. The method for manufacturing the waveguide component 100 according to this embodiment has a first step, a second step, and a third step. The first step is a step for producing a resin part R. The second step is a step for covering the resin part R with a coating film C. The third step is a step for joining the first part 10 and the second part 20. The specific steps will be described below.

In the first step, two or more resin parts R are produced. The resin parts are produced using additive manufacturing, a processing method that joins materials together to form three-dimensional objects. Additive manufacturing is also known as 3D printing.

The additive manufacturing technology used in the first step is, for example, powder bed fusion. Powder bed fusion can manufacture objects with higher toughness than stereolithography. On the other hand, objects obtained by powder bed fusion have a rougher surface than objects manufactured by stereolithography, which produces a glossy finish. For example, the surface roughness (Ra) of the resin part R manufactured using powder bed fusion is 20 μm or more. When stereolithography is used, the surface roughness (Ra) is less than 20 μm.

In powder bed fusion, the powdered raw material is melted with a laser or other tool, and the molten raw material is re-solidified, a process that is repeated layer by layer to form an object. The density of the molded plastic part R varies depending on the laser output. If the laser output is high, the powdered raw material melts sufficiently, increasing the density of the molded product. If the laser output is low, or the laser is not irradiated, some voids will remain between the powdered raw material, decreasing the density of the molded product. If the density of the outer surface and interior of the plastic part R is to be different, the laser output when molding the area corresponding to the outer surface of the plastic part R is increased compared to the laser output when molding the interior.

Next, in the second step, the outer surface of each of the resin parts R is coated with a material having a higher electrical conductivity than the resin material constituting the resin parts R. Since the resin parts R that will become the first part 10 and the resin parts R that will become the second part 20 are each coated with the coating film C separately, the coating film C can be applied substantially uniformly to the grooves 10a, 20a of the first part 10 and the second part 20, respectively.

The coating film C is produced, for example, by plating or applying a conductive paint. In the case of plating, electroless plating is performed followed by electrolytic plating. Electroless plating alone does not ensure a sufficient thickness of the coating film C, and it is difficult to make the surface roughness (Ra) of the coating film C smaller than the surface roughness (Ra) of the resin part R. By coating the resin part R with the coating film C, the first part 10 and the second part 20 are obtained.

Next, in the third step, the resin part R coated with the coating film C is bonded to form the waveguide Wg on the bonding surface. As described above, the first part 10 and the second part 20 are manufactured separately. By bonding the first part 10 and the second part 20 together, the waveguide Wg is formed between the bonding surfaces. By bonding the first part 10 and the second part 20, which are manufactured separately, the flatness of the inner surface of the waveguide Wg can be made approximately uniform. Furthermore, even if multiple waveguide components 100 are manufactured, the state of the inner surface of the waveguide Wg can be easily reproduced by making them into separate parts.

The waveguide component 100 according to this embodiment is lighter than a waveguide component made of metal because the inside is made of resin. As will be shown in detail in the examples, the waveguide component 100 according to this embodiment has the same performance as a waveguide component made of metal. Furthermore, by using additive manufacturing technology, complex shapes can be easily formed and processing costs can be reduced. Furthermore, because the inside of the waveguide component 100 is made of resin, it has lower thermal conductivity than a waveguide component made of metal. Therefore, the waveguide component 100 is less susceptible to the effects of external heat and can be used in harsh applications where the outside temperature changes drastically, such as aerospace parts.

The above describes in detail the preferred embodiment of the present invention, but the present invention is not limited to a specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims.

For example, FIG. 6 is a perspective view of a waveguide component 101 according to a first modified example. The waveguide component 101 according to the first modified example differs from the waveguide component 100 shown in FIG. 1 in the shapes of the first part 11 and the second part 21. In the waveguide component 101, the flange F belongs to the first part 11 and is not divided. The first part 11 has a main part that forms the waveguide Wg and disks at both ends of the main part in the transmission direction. The disks become the flange F of the waveguide component 101. The second part 21 is made of the main part (flat plate) that forms the waveguide Wg. The second part 21 is fitted between the disks at both ends of the first part 11 to form the waveguide component 101.

The waveguide component 101 of the first modified example has the same effect as the waveguide component 100, except that the parts are divided differently.

For example, FIG. 7 is a perspective view of the first part 12 constituting the waveguide component 102 according to the second modified example. For the sake of explanation, the second part is not shown in FIG. 7. The waveguide component 102 according to the second modified example differs from the waveguide component 100 shown in FIG. 1 in that a rib L is provided on the waveguide Wg. The rib L is provided so as to intersect with the transmission direction of the waveguide Wg. The rib L is, for example, in the groove 12a of the first part 12. The waveguide component 102 functions as a filter by having the rib L.

The waveguide component 102 of the second modified example differs only in that it has a rib L, and provides the same effect as the waveguide component 100.

Example 1
First, a resin part was produced by powder bed fusion bonding using nylon 11 as the resin material. The laser output during production of the resin part was constant, and the density of the resin part was approximately uniform. Two resin parts were produced, each of which had the same shape as the first part 10 and the second part 20 of the waveguide component 100 shown in Figure 1. The surface roughness (Ra) of the resin part was measured and found to be 26.3 μm.

Next, each of the two resin parts was subjected to a plating process. First, the resin parts were immersed in an electroless nickel plating solution at 45°C for 10 minutes to perform an electroless plating process. Next, the resin parts after the electroless plating process were electroplated. The electrolytic plating was performed for 40 minutes at 3 A/ ^dm2 using a copper sulfate plating solution at 23°C. The obtained coating film was a copper plating film, and its thickness was 25 μm. The surface roughness (Ra) of the parts corresponding to the grooves 10a, 20a of the first part 10 and the second part 20 was measured and found to be 14.9 μm.

Then, the first part 10 and the second part 20 thus prepared were joined to produce the waveguide component 100. The length of the waveguide component 100 was 5 cm, and the yz cross section of the waveguide Wg was rectangular. The length of the long side of the waveguide Wg was 2.54 mm, and the length of the short side was 1.27 mm. The joining surface was provided so as to pass through the center of the long side of the waveguide Wg and to extend in the xz direction.

(Comparative Example 1)
The waveguide component of Comparative Example 1 differs from Example 1 in that it is made of metal. The waveguide component of Comparative Example 1 was produced by brazing a flange to a tube that forms a waveguide produced by drawing. The configuration of the waveguide component of Comparative Example 1 was the same as that of the waveguide component of Example 1. The metal that constitutes the waveguide component was a copper alloy.

Figure 8 is a diagram showing the transmission characteristics of Example 1 and Comparative Example 1. Figure 8 shows the S parameters of the waveguide components of Example 1 and Comparative Example 1. As shown in Figure 8, the waveguide component of Example 1 exhibited performance equivalent to that of the waveguide component of Comparative Example 1. It is believed that the waveguide component of Example 1 adequately maintains its transmission characteristics for high-frequency signals by smoothing the rough surface of the resin part with metal plating.

Example 2
Example 2 differs from Example 1 in that a rib L is provided on the resin part, and the structure is similar to that of the waveguide component 102 shown in Fig. 7. Other manufacturing conditions were the same as those of Example 1. The surface condition of the waveguide component 102 was also equivalent to that of the waveguide component of Example 1.

(Comparative Example 2)
A waveguide component having ribs L was fabricated by cutting aluminum. The structure of the waveguide was the same as that of Example 2.

Figure 9 shows the characteristics of the filters of Example 2 and Comparative Example 2. Figure 9 also shows the design values of the filters. As shown in Figure 9, the filter of Example 2 exhibited performance equivalent to that of the filter of Comparative Example 1.

The waveguide component according to this embodiment can be used in satellite-mounted components in the aerospace industry, components for mobile phones of generations beyond 5G that use millimeter-wave bands, components for millimeter-wave radar, components for millimeter-wave non-destructive testing equipment, etc.

10, 11, 12 First part 10a, 20a Groove 20, 21, 22 Second part 100, 101, 102 Waveguide component C Covering film R Resin part M Main part F Flange Wg Waveguide Ia First current line Ib Second current line S1 First surface S2 Second surface L Rib

Claims (6)

A first part and a second part are joined together,
At least one of the first component and the second component has a groove on a joining surface thereof that becomes a waveguide when joined together,
The first component and the second component each include a resin component containing a resin and a coating film covering the resin component and having a higher electrical conductivity than the resin,
In the groove, the arithmetic surface roughness (Ra) of the coating film is smaller than the arithmetic surface roughness (Ra) of the resin part,
A waveguide component , wherein the coating film has an arithmetic surface roughness (Ra) of less than 20 μm, and the resin part has an arithmetic surface roughness (Ra) of 20 μm or more. A first part and a second part are joined together,
At least one of the first component and the second component has a groove on a joining surface thereof that becomes a waveguide when joined together,
The first component and the second component each include a resin component containing a resin and a coating film covering the resin component and having a higher electrical conductivity than the resin,
In the groove, the arithmetic surface roughness (Ra) of the coating film is smaller than the arithmetic surface roughness (Ra) of the resin part,
The resin part has an outer surface having a higher density than an inner surface of the waveguide component. The waveguide component according to claim 1 or 2, wherein the coating film is a metal plating film. a flange is provided at each end in a transmission direction when the first component and the second component are joined together;
The waveguide component according to claim 1 , wherein the flange is divided on either side of the joining surface. a cross section of the waveguide cut by a plane perpendicular to the transmission direction has a rectangular shape;
the waveguide has two first surfaces through which a first current having a component in the transmission direction flows, and two second surfaces through which a second current perpendicular to the transmission direction flows;
The waveguide component of claim 1 , wherein the joining surface intersects with the first surface. A first step of fabricating two or more resin parts using additive manufacturing techniques;
a second step of covering an outer surface of each of the resin parts with a material having a higher electrical conductivity than a resin material constituting the resin parts;
and a third step of bonding the resin part covered with the coating film to form a waveguide on the bonding surface,
The additive manufacturing technique in the first step is powder bed fusion;
In the second step, electroless plating is performed and then electrolytic plating is performed .

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