JP2010114826A - Method of manufacturing waveguide slot antenna substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a slot antenna substrate having high dimensional accuracy of an antenna opening in a waveguide slot antenna substrate with a through-hole and the antenna opening. <P>SOLUTION: The method has a half etching step of reducing the film thickness of a copper foil 2 of a copper-clad substrate 1, a boring step of forming a through-hole 4a in a desired region of the copper foil 2, an electroless plating step of making the copper foil 2 and an inner wall surface of the through-hole 4a conductive by immersing the copper-clad substrate 1 in a solution, a photoengraving step of forming an antenna opening 3 whose periphery is enclosed with the copper foil 2 in a region except a desired region, a waveguide connection pattern formation step of forming a waveguide transforming part 5a whose periphery is enclosed with the copper foil 2 in a region except a desired region separated from the antenna opening 3, an inspection step of measuring the size of the formed antenna opening 3 and an electrolytic plating step of forming a metal layer 8 laminated in the inner wall surface of the through-hole 4a and laminated in the outer circumference of the antenna opening. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a method for manufacturing a waveguide slot antenna substrate in which an opening of a waveguide slot antenna used in a high frequency band such as a millimeter wave is formed with high accuracy to improve antenna characteristics.

For example, in FIG. 1 (see Patent Document 1) of Japanese Patent Laid-Open No. 2002-344117, a printed wiring board having a thickness of 12 μm or less as a method for easily forming a copper wiring pattern having a target design value width and thickness is disclosed. A method of forming a fine pattern in which a copper foil is patterned by a subtractive method and then copper is plated on the pattern by an electrolytic copper plating method is disclosed.

Japanese Patent Laid-Open No. 2002-344117 (paragraph “0017” in FIG. 1)

However, although the thing of patent document 1 uses the thin thing of the copper foil 2, since it is possible to form a pattern with high dimensional accuracy, normally a copper clad laminated board is copper foil and When the thin copper foil is used to firmly adhere to the base material by the anchor effect, it is necessary to make the adhesive surface smooth and the surface area is reduced, resulting in a decrease in peel strength. That is, if the peel strength between the copper foil 2 and the substrate 1 is lowered, the peel strength may be further lowered due to the action of a solution or the like at the time of etching. There was a problem that peeling occurred. Moreover, in patent document 1, the relationship between an antenna opening part and a through-hole part is not mentioned.

The present invention has been made in order to solve the above-mentioned problems, and in a waveguide slot antenna substrate having a through hole portion and an antenna opening portion, a waveguide slot antenna having a high dimensional accuracy of the antenna opening portion. An object is to provide a method for manufacturing a substrate.

A method for manufacturing a waveguide slot antenna substrate according to a first aspect of the present invention includes a half-etching step of etching a copper foil of a copper-clad substrate to reduce the film thickness of the copper foil, and penetrating a desired region of the copper foil. A perforating step of providing a hole, a non-electrolytic plating step of immersing the copper-clad substrate in a solution to make the copper foil and the inner wall surface of the through-hole part conductive, and the periphery is a copper foil in a region other than the desired region A photoengraving process for forming an enclosed antenna opening by etching, and a waveguide for etching to form a waveguide converter surrounded by copper foil in a region other than the desired region apart from the antenna opening. A tube connection pattern forming step, an inspection step for measuring the dimension of the formed antenna opening, and an electrolytic layer for forming a metal layer to be laminated on the inner wall surface of the through hole and at the outer periphery of the antenna opening. A step of controlling the concentration of the solution, the plating energy, or the dipping time in the electrolytic plating step from information on the pre-calculated amount of the metal layer and the amount of side surface adhesion of the antenna opening. The opening area of the opening is reduced to a predetermined size.

In the method for manufacturing a waveguide slot antenna substrate according to a second aspect of the present invention, the through hole is provided along both sides from the waveguide converter to the antenna opening, and the through hole is a barrier. The high-frequency power transmission path propagating through the copper-clad substrate is configured as follows.

A method for manufacturing a waveguide slot antenna substrate according to a third aspect of the present invention is the method according to the first or second aspect, wherein the antenna openings are arranged in an array.

According to the first aspect of the present invention, since the pattern size of the antenna opening formed in the photoengraving process is measured and then the outer peripheral side surface adhesion amount of the antenna opening is adjusted in the electrolytic plating process. By accurately controlling the size of the adhesion amount, there is an effect of reducing the loss of the antenna gain of the high frequency power and the shift of the pass loss of the effective pass bandwidth.

According to the second aspect of the present invention, in addition to the effect of the first aspect, the high-frequency power transmission path propagating in the dielectric of the copper-clad substrate from the waveguide conversion portion to the antenna opening is provided on both sides. Since the through-hole portion is provided as the barrier provided along, there is an effect of preventing a leakage of high-frequency power in the transmission path and obtaining a waveguide slot antenna substrate with a small transmission loss.

According to the third aspect of the present invention, since the plurality of antenna openings are arranged in an array, the effective area of the antenna opening is expanded, the transmission / reception area as a slot antenna is widened, and a wide range of transmission / reception is possible. .

Embodiment 1 FIG.
A waveguide slot antenna substrate according to Embodiment 1 of the present invention will be described below with reference to FIG. FIG. 1 is a perspective view of a waveguide slot antenna substrate according to the first embodiment. In FIG. 1, 1 is a copper-clad substrate (copper-clad laminate) in which copper foils are formed on both sides of a base material, 1a is a dielectric that serves as a base material of the copper-clad substrate 1, and 2 is a surface copper foil of the copper-clad substrate 1. And having copper foils 2a and 2b on both sides of the dielectric 1a. Reference numeral 3 denotes an antenna opening (opening pattern) having a function of transmitting high-frequency power such as a millimeter wave band to the outside or receiving external radio waves, and 4 is a through-hole portion that electrically connects the front and back of the copper-clad substrate 1. Reference numeral 5 denotes a waveguide connected to the copper-clad substrate 1, and 5a denotes a connection part (waveguide converter) between the waveguide 5 and the copper-clad board 1, and a part of the pattern of the copper foil 2b is stripped off. Thus, it is configured to be connected (converted) to the end of the waveguide 5.

FIG. 2 is a plan view of the surface of the waveguide slot antenna substrate shown in FIG. 1. The high frequency power from the connecting portion 5a to the waveguide 5 is divided into the copper-clad substrate 1 with the through hole portion 4 as a barrier. Waves are transmitted to the antenna opening 3 side. That is, a dielectric waveguide is formed by the through-hole portion 4 and the surface copper foil 2, and high frequency power propagates to the plurality of antenna openings 3. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

FIG. 3 is a cross-sectional view of the waveguide slot antenna substrate shown in FIG. 2 taken along the line AA. The copper foil 2a is provided with the antenna opening 3 from which the surrounding copper foil is removed. A waveguide converter 5a from which the surrounding copper foil is removed is installed on the copper foil 2b. Reference numeral 6 denotes a connection means composed of a solder material or a conductive adhesive for fixing the waveguide 5 and the copper-clad substrate 1. The high-frequency power propagating through the copper-clad substrate 1 is bidirectional. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

Next, the operation will be described. In FIG. 1, the high-frequency power (signal) transmitted from the waveguide 5 is taken into the dielectric (waveguide) by the waveguide converter 5a, and the surface copper foil 2 and the through hole serving as the ground conductor. It propagates toward the antenna opening 3 through the inside of the dielectric 1 a surrounded by the portion 4. The antenna opening 3 is formed in an array shape and has a long groove shape with a predetermined electrical wavelength length. In addition, the through-hole portion 4 serves not only to electrically connect the copper foil 2a serving as the short-circuit ground conductor and the copper foil 2b serving as the ground conductor, but also serves as an impedance adjustment function with the antenna opening 3 and the waveguide 5.

FIG. 4 is a partially enlarged plan pattern diagram of the surface of the waveguide slot antenna substrate shown in FIG. 1. The antenna opening 3 has a dimension width (W) of 0. 0 with respect to a predetermined design center frequency (fc). Corresponding to 2 mm and dimension length (L) of 1.7 mm, the width of the copper foil 2 a is 0.24 mm (W) × 1.74 mm (L). In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

Next, a method for manufacturing the waveguide slot antenna substrate according to the first embodiment of the present invention will be described with reference to FIG. In FIG. 5, 4a is a through-hole portion before forming the through-hole portion 4, 7 is a copper plating layer (electroless plating layer), 8 is a metal layer (electrolytic plating layer), and 21a and 21b are surface copper foils (copper foil). Reference numerals 2a and 2b denote copper foils that have been thinned by half etching.

FIG. 5A shows a copper-clad laminate (copper-clad substrate) 1, and a general-purpose base material using a BT resin or a general-purpose FR-4 material is suitable for the dielectric 1a. The surface copper foil 2 is suitably a general-purpose copper foil using rolled copper or electrolytic copper, 2a is a conductive foil formed on one surface side of the dielectric 1a, and 2b is formed on the other surface side of the dielectric 1a. Use conductive foil. The conductive foil 2 has a thickness of 18 μm (1/2 ounce copper foil) on each side. In the copper-clad laminate 1, the bonding surface between the copper foil 2 and the substrate 1a is firmly bonded by an anchor effect (biting). Although the first embodiment has been described using a double-sided copper-clad substrate, a dielectric 1a using a multilayer prepreg may be used.

FIG. 5B shows a half-etching step, and the copper-clad laminate 1 of FIG. 4A is half-etched with the surface copper foil 2 using an etching solution, thereby a copper foil 21a having a thickness of 5 to 6 μm. , 21b is obtained. In half-etching, both copper foils 2a and 2b are thinned in the first embodiment. However, when the antenna opening 3 is on one surface, only the copper foil 2a may be thinned.

FIG.5 (c) has shown the drilling process which forms the through-hole part 4, and forms the through-hole 4a which penetrates the front and back of the copper clad laminated board 1 by NC (numerical control) in a desired area | region with equal intervals by a drill To do.

FIG.5 (d) has shown the electroless-plating process, the copper clad laminated board 1 is immersed for about 5 to 10 minutes in the tank which used the chemical copper as the plating solution, and the inside of the through-hole (through-hole part) 4a mainly A copper plating layer 7 is applied to the wall surface to ensure conduction between the front and back copper foils 2 of the dielectric 1a. In the first embodiment, the copper plating layer 7 uses a copper material. However, even if it is an electroless nickel plating using a nickel (Ni) material, the copper plating layer 7 plays an equivalent role. In addition, since the electroless plating process is intended to conduct the through hole 4a, a region other than the through hole 4a of the surface copper foil 2 may be masked to prevent the plating material from adhering to the surface. In addition, what plated the through-hole (through-hole part) 4a is called the through-hole hole part 4. FIG.

FIG. 5E shows a photolithography process, which is exposed and developed using a photosensitive photoresist (not shown), etched, and has a size of 0.24 mm (W) × 1.74 mm (L). A predetermined antenna opening 3 is formed. Therefore, the antenna opening 3 has a blank pattern in which the periphery is covered (enclosed) with the copper foil 2. Similarly, a part of the surface copper foil 2 is also peeled off from the waveguide conversion portion 5a apart from the antenna opening 3 to form a removal pattern. The formation process of the waveguide conversion part 5 (waveguide connection pattern formation process) is performed in advance in the previous process by etching because only a part of the pattern of the copper-clad laminate 1 is peeled off according to the shape of the waveguide 5. You can keep it. In addition, when it does not interfere with the transmission / reception area, the waveguide converter 5 may be installed on the surface copper foil 2a side.

FIG. 5 (f) shows an electrolytic plating process, in which the copper-clad laminate 1 is immersed in an electrolytic copper plating solution tank, and the antenna layer 3 is mainly plated with a metal layer 8 around the antenna opening 3. The side surface (thickness direction) is also plated with copper. At the same time, the conduction of the inner wall surface of the through-hole portion 4a is enhanced. The through hole 4a with enhanced conduction is referred to as a through hole 4.

In the first embodiment, a copper material is used for the metal layer 8, but an equivalent role is achieved even by electrolytic gold plating using a gold (Au) material such as electrolytic gold.

The plating thickness in the electrolytic plating process is set according to the reliability of the through hole with respect to the use environment of the equipment, the substrate thickness, etc., and is preferably 10 μm to 30 μm. In the first embodiment, since the plating thickness of the through-hole hole 4 is about 20 μm, the size of the antenna opening in the pre-electrolytic plating process is a surface shape whose width and length are larger than the design size. That is, the dimensions are larger than the outer circumference determined by the width and length. In FIG. 5, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

FIG. 6 is a diagram for explaining the dimensions of the antenna opening 3 installed in the copper clad laminate 1 with reference to the BB cross section of FIG. Although the electroless plating layer 7 adheres to the copper foil 2a, the plating layer of the antenna opening 3 is etched in the photolithography process. Accordingly, the opening pattern 3 dimension (W) defined by the photosensitive photoresist size is formed to be 0.24 mm. Similarly, the opening pattern 3 dimension (L) is 1.74 mm.

From the above, in the first embodiment, the dimension (W) of the opening pattern after plating in the electrolytic plating process is accurately set to 0.20 mm, and the dimension (L) of the opening pattern is accurately set to 1.70 mm. Therefore, the amount of side surface adhesion of the metal layer 8 attached to the outer peripheral side surface of the opening pattern 3 is controlled.

FIG. 7 is a diagram for explaining the frequency characteristics related to the antenna gain when the dimensions of the antenna opening 3 of the waveguide slot antenna substrate are changed. fh is the passband upper limit frequency, fl is the passband lower limit frequency, fc is the passband center frequency, and the pattern size of the antenna opening 3 is 1.7 mm (L) X 0.2 mm (W) as the optimum value. The loss (gain loss) is about 0.5 dB with a dimensional deviation of 15 μm with respect to a predetermined pass band, and about 1.5 dB with a dimensional deviation of 30 μm, and the pattern accuracy of the antenna opening 3 has a great influence on the antenna gain loss. Can be seen. There is also a shift in gain loss for a predetermined passband width (fl to fh).

FIG. 8 is a diagram showing the relationship between the adhesion time (immersion time) of electrolytic copper adhering to the side surface of the antenna opening 3 and the adhesion amount (adhesion width). In FIG. 8, it is understood that there is a change in the side surface adhesion amount of about 30 μm depending on the electrolytic copper solution concentration (A> B), the plating current (A> B), and the immersion time. Using this change in adhesion amount as an information, an optimum adhesion amount is applied in the electrolytic plating process. That is, when the pattern size of the antenna opening 3 is 1.70 mm (L) X 0.2 mm (W), the outer peripheral dimension of the antenna opening 3 is measured (inspected) after the photolithography process 5 (e). To do. Then, after obtaining the difference between the optimum value and the average value of the measured dimensions of each antenna opening 3, in electrolytic plating step 5 (f), the solution concentration, electrolytic plating energy corresponding to the difference (plating voltage, plating current, plating) Pulse duration, etc.) or control immersion time.

That is, after measuring the pattern dimension of the antenna opening 3 formed in the photoengraving process, the amount of adhesion of the outer peripheral side surface of the antenna opening 3 is controlled in the electrolytic plating process to reduce the opening area of the antenna opening 3 to a predetermined dimension. Adjust to.

The antenna surrounded by the metal layer 8 by controlling the concentration of the solution and the immersion time in the electrolytic plating process from the relationship (information) between the coating amount of the metal layer 8 calculated in advance and the side surface adhesion amount of the opening pattern portion 3. Since the size of the opening 3 is adjusted to the optimum value, it is possible to control the size of the side surface adhesion amount of the opening pattern 3 with high accuracy. Even if there is a shift in the pass loss, there is an effect of reducing the shift in the pass loss of the effective pass bandwidth defined in the specification.

Embodiment 2. FIG.
A waveguide slot antenna substrate according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 9 is a cross-sectional view of a waveguide slot antenna substrate according to the second embodiment. In FIG. 9, 11 is a dielectric (reinforcing plate) affixed on both sides via the copper-clad laminate 1, and the copper-clad laminate 1 except for the installation area of the antenna opening 3 and the waveguide converter 5a. The structure is covered. 9, the same reference numerals as those in FIG. 3 denote the same or corresponding parts.

Next, the operation will be described. The point that the dielectric waveguide is formed by the surface copper foil 2 is the same as that of the first embodiment. In FIG. 9, the high-frequency power transmitted from the waveguide 5 is taken into the dielectric waveguide by the waveguide converter 5a, and is surrounded by the surface copper foil 2 and the through-hole portion 4 serving as a ground conductor. It propagates through the inside of the dielectric 1 a toward the antenna opening 3. The antenna opening 3 is formed in an array shape and has a long groove shape with a predetermined electrical wavelength length.

Further, the through-hole portion 4 electrically connects the surface copper foil 2a serving as the short-circuit ground conductor and the surface copper foil 2b serving as the ground conductor. Moreover, the mechanical strength of the transmission line by the ground conductors such as the copper foils 2a and 2b is enhanced by attaching the reinforcing plate 11 such as a dielectric so as to sandwich the transmission line along the transmission line of the dielectric waveguide. It is configured to do. In addition, the electric performance of the transmission line including the ground conductor of the surface copper foil 2 may be enhanced by attaching a metal plate (reinforcing plate) instead of the dielectric, and electromagnetic shielding is applied to the surface of the dielectric or the metal plate. A paint or moisture-proof paint may be applied.

From the above, according to the waveguide slot antenna substrate according to the second embodiment, the reinforcing plate 11 is attached to the transmission line in which the dielectric waveguide is formed by the surface copper foil 2, and the electromagnetic shielding paint is applied to the surface of the reinforcing plate 11. In addition, the mechanical strength of the transmission line of the dielectric waveguide can be enhanced by applying a moisture-proof coating, and the performance of the waveguide slot antenna substrate can be stably maintained even if the environmental conditions change.

It is a perspective view of the waveguide slot antenna board | substrate by Embodiment 1 of this invention. It is a top view of the waveguide slot antenna board | substrate surface by Embodiment 1 of this invention. It is sectional drawing of the waveguide slot antenna board | substrate shown in FIG. 2 by Embodiment 1 of this invention. It is a partial expansion plane pattern figure of the waveguide slot antenna board | substrate surface by Embodiment 1 of this invention. It is a figure explaining the manufacturing method of the waveguide slot antenna board | substrate by Embodiment 1 of this invention. It is a figure explaining the dimension of the antenna opening part installed in the copper clad board | substrate of the waveguide slot antenna board | substrate by Embodiment 1 of this invention. It is a figure explaining the frequency characteristic regarding the antenna gain when the dimension of the antenna opening part of the waveguide slot antenna board | substrate by Embodiment 1 of this invention changes. It is a figure which shows the relationship between the adhesion time of the electrolytic copper adhering to the side surface of the antenna opening part of the waveguide slot antenna board | substrate by Embodiment 1 of this invention, and the adhesion amount. It is sectional drawing of the waveguide slot antenna board | substrate by Embodiment 2 of this invention.

Explanation of symbols

1 .. Copper-clad laminate (copper-clad substrate) 1a .. Dielectric (base material) 2 .. Copper foil (surface copper foil)
2a .. One surface copper foil (copper foil) 2b .. The other surface copper foil (copper foil)
3. ・ Antenna opening (opening pattern) 4. ・ Through hole 4a ・ ・ Through hole (through hole) 5. ・ Waveguide 5a ・ ・ Waveguide converter (connection part)
6. ・ Connecting means 7 ・ ・ Copper plating layer (electroless plating layer) 8. ・ Metal layer (electrolytic plating layer)
11 .. Reinforcement plate 21 .. Thinned surface copper foil 21a ... Copper foil 21b ... Copper foil

Claims (3)

Etching the copper foil of the copper-clad substrate and reducing the film thickness of the copper foil; a drilling step of providing a through hole in a desired region of the copper foil; and immersing the copper-clad substrate in a solution An electroless plating step for making the foil and the inner wall surface of the through hole portion conductive, a photoengraving step for etching to form an antenna opening surrounded by a copper foil in a region other than the desired region, and the antenna A waveguide connection pattern forming step for etching to form a waveguide converter surrounded by copper foil in a region other than the desired region apart from the opening, and measuring the dimensions of the formed antenna opening And an electroplating step of forming a metal layer that is laminated on the inner wall surface of the through-hole portion and that is laminated on the outer periphery of the antenna opening, The waveguide slot antenna having a predetermined size by reducing the opening area of the antenna opening by controlling the concentration of the solution, the plating energy, or the dipping time in the electrolytic plating process based on the information about the amount of the side opening of the opening. A method for manufacturing a substrate. The through hole is provided along both sides from the waveguide converter to the antenna opening, and constitutes a transmission path for high-frequency power propagating through the copper-clad substrate using the through hole as a barrier. A method for manufacturing a waveguide slot antenna substrate according to claim 1. The method of manufacturing a waveguide slot antenna substrate according to claim 1 or 2, wherein the antenna openings are arranged in an array.

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