High-transmittance microstrip patch antenna and manufacturing method thereof

Abstract

The invention discloses a high-transmittance microstrip patch antenna and a manufacturing method thereof, the high-transmittance microstrip patch antenna comprises a transparent substrate base material, one surface of the transparent substrate base material is provided with a radiation unit metal grid layer, the other surface of the transparent substrate base material is provided with a grounding plate metal grid layer, the upper surface and the lower surface of the transparent substrate base material are provided with grooves, and the upper surface and the lower surface of the transparent substrate base material are respectively provided with a metal grid layer. The groove is filled with conductive metal to form a conductive metal layer, and the radiation unit metal grid layer and the grounding plate metal grid layer are embedded into the groove; through the structure of embedding the metal grids in the grooves and the complementary topology design, while the radiation unit maintains the solid grids to guarantee the radio frequency performance, the metal shading area is reduced through the hollowing of the grounding plate, and the collaboration of the visible light wave band transmittance and the square resistance is remarkably optimized in combination with the metal thickness gradient formed by the depth difference of the grooves; a double-sided alignment laser system is adopted to realize the alignment precision, and the problem of port isolation deterioration caused by pattern dislocation is radically inhibited.

Description

Technical Field

[0001] This invention relates to the technical field of transparent antennas, specifically to a high-transparency microstrip patch antenna and its manufacturing method. Background Technology

[0002] With the rapid development of intelligent display devices, stealth communication systems, and IoT terminals, transparent thin-film antennas have become a research hotspot due to their visual concealment and spatial adaptability. Microstrip patch antennas, as the mainstream antenna type, traditionally consist of a dielectric substrate, a surface radiating patch, and a back ground plane. To achieve transparency, existing technologies mainly adopt the following solutions:

[0003] Magnetron sputtering deposits an ITO layer on a glass or PET substrate, and photolithography forms the radiating units and ground plane. However, ITO has a high sheet resistance and high high-frequency loss, which leads to a decrease in radiation efficiency. It is also brittle and prone to cracking when bent, which cannot meet the requirements of flexible devices.

[0004] Metal meshes are fabricated on the substrate surface using nanoimprinting or electroforming processes. However, these exposed metal meshes are prone to oxidation and detachment. The ground plane and radiating unit need to be fabricated separately and then laminated for alignment, resulting in large misalignment errors and impedance mismatch. Furthermore, the mesh exhibits obvious moiré fringes after the two layers of metal are stacked.

[0005] In summary, existing solutions cannot simultaneously meet the technical specifications of visible light transmittance and sheet resistance; low double-sided pattern alignment accuracy leads to deterioration of port isolation; multiple bonding introduces bubbles or wrinkles, resulting in deviations in dielectric constant uniformity. Summary of the Invention

[0006] The purpose of this invention is to provide a high-transmittance microstrip patch antenna and its manufacturing method, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a high-transmittance microstrip patch antenna, comprising a transparent substrate, wherein a radiating element metal mesh layer is provided on one side of the transparent substrate, and a ground plane metal mesh layer is provided on the other side of the transparent substrate. Grooves are provided on both the upper and lower surfaces of the transparent substrate, and conductive metal is filled in the grooves to form a conductive metal layer. The radiating element metal mesh layer and the ground plane metal mesh layer are both embedded in the grooves.

[0008] Preferably, the transparent substrate is a flexible transparent polymer film with a thickness of 50-200 μm, and is made of polyethylene terephthalate, cyclic olefin polymer, or transparent polyimide transparent substrate.

[0009] Preferably, the radiating unit metal mesh layer and the grounding plate metal mesh layer adopt a complementary topology, with the radiating unit being a solid mesh frame and the grounding plate being a hollow mesh.

[0010] Preferably, the conductive metal layer is composed of a bottom bonding layer and a main conductive layer. The bottom bonding layer is a titanium or chromium layer with a thickness of 0.1-0.5 μm, which directly contacts the bottom surface of the groove. The main conductive layer is a silver or copper layer with a thickness of 1-10 μm, which covers the bottom bonding layer.

[0011] A method for manufacturing a high-transmittance microstrip patch thin-film antenna, the method comprising the following steps:

[0012] S1: Two peelable transparent substrates are bonded to the upper and lower surfaces of a transparent substrate by hot pressing to form a three-layer composite structure. The thickness of the transparent substrate is 5–10 μm.

[0013] S2: A composite structure with synchronous etching using a dual-face aligned laser system is adopted. The upper laser head etches the radiation unit grid groove on the top substrate, and the lower laser head etches the ground plane grid groove on the bottom substrate. The etching depth penetrates the transparent substrate and extends to 1–5 μm below the surface of the transparent substrate.

[0014] S3: Conductive metal is deposited on the grooved surface through a vacuum sputtering process, so that the metal fills the groove and covers the surface of the transparent substrate.

[0015] S4: Peel off the transparent substrate, retaining the metal mesh structure embedded in the transparent substrate;

[0016] S5: Electroplating is applied to thicken the exposed metal mesh so that the metal layer thickness reaches 90–110% of the groove depth.

[0017] Preferably, the dual-sided alignment laser system includes a laser device, and the composite substrate has positioning holes at its four corners with a diameter of 0.5 mm; the laser device is equipped with a coaxial CCD positioning camera.

[0018] Preferably, in the vacuum sputtering process, the metal layer inside the groove and the metal layer on the outer plane of the groove form a thickness difference through the difference in etching depth, and the thickness of the metal inside the groove is 1.5–3 times the thickness of the metal outside the groove.

[0019] Preferably, the surface of the transparent substrate is formed with raised metal mesh lines, the height of which is 1–8 μm and the line width is 3–5 μm.

[0020] Preferably, the surface of the metal mesh structure is coated with a transparent insulating layer with a thickness of 0.5–2 μm, which covers the metal mesh and fills the mesh gaps.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. This invention utilizes a groove-embedded metal mesh structure and complementary topology design to maintain a solid mesh in the radiating unit to ensure radio frequency performance, while reducing the metal light-shielding area by hollowing out the ground plane. Combined with the metal thickness gradient formed by the groove depth difference, it significantly optimizes the synergy between transmittance and sheet resistance in the visible light band.

[0023] 2. This invention uses a double-sided alignment laser system to achieve alignment accuracy, fundamentally suppressing the problem of port isolation deterioration caused by pattern misalignment. The single hot-pressing composite process can peel off the sacrificial layer substrate, completely avoiding bubbles, wrinkles and dielectric constant non-uniformity caused by multiple bonding.

[0024] 3. The design of the groove extending 1–5 μm into the substrate, combined with a titanium or chromium bonding layer, improves the adhesion stability of the metal mesh under flexible bending; the end electroplating precisely controls the metal volume and the transparent insulating coating, simultaneously achieving the high-frequency conductivity requirement and optical surface flatness. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the layered structure of the high-transmittance microstrip patch antenna of the present invention.

[0026] Figure 2 This is a schematic diagram of the structure of the radiating unit pattern layer and the ground plane pattern layer with grooves of the present invention.

[0027] Figure 3 This is a schematic diagram of the structure of the vacuum sputtered conductive metal layer of the present invention.

[0028] Figure 4 This is a schematic diagram of the transparent thin-film antenna of the present invention.

[0029] In the figure: transparent substrate 1; groove 11; radiating unit metal mesh layer 2; ground plane metal mesh layer 3; transparent substrate 4; conductive metal layer 5. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Please see Figures 1 to 4This invention provides a technical solution: a high-transmittance microstrip patch antenna, comprising a transparent substrate 1, a radiating element metal mesh layer 2 disposed on one side of the transparent substrate 1, a ground plane metal mesh layer 3 disposed on the other side of the transparent substrate 1, grooves 11 being formed on both the upper and lower surfaces of the transparent substrate 1, the grooves 11 being filled with conductive metal to form a conductive metal layer 5, the radiating element metal mesh layer 2 and the ground plane metal mesh layer 3 being embedded in the grooves 31, the metal mesh embedded in the grooves forming a raised wire structure, the metal being embedded inside the substrate, avoiding edge burrs caused by traditional etching, and improving the continuity of radio frequency current.

[0032] The transparent substrate 1 is a flexible transparent polymer film with a thickness of 50-200μm. It is made of polyethylene terephthalate, cyclic olefin polymer, and transparent polyimide. The 50-200μm flexible substrate provides mechanical support and optical transmittance. The ultra-thin design reduces light scattering and improves visible light transmittance. The polymer material has a stable dielectric constant, which reduces the dielectric constant deviation caused by environmental temperature and humidity.

[0033] The radiating unit metal mesh layer 2 and the grounding metal mesh layer 3 adopt a complementary topology. The radiating unit is a solid mesh frame, and the grounding unit is a hollow mesh. The solid mesh of the radiating unit ensures current distribution, and the hollow grounding unit reduces metal shading.

[0034] The solid radiating unit grid period is λ / 10–λ / 8, and the perforation rate of the hollow ground plane is 70–85%. The solid grid period ensures continuous current distribution; the high perforation rate increases the light transmittance of the ground plane.

[0035] The conductive metal layer 5 consists of a bottom bonding layer and a main conductive layer. The bottom bonding layer is a titanium or chromium layer with a thickness of 0.1-0.5μm, which directly contacts the bottom surface of the groove 11. The main conductive layer is a silver or copper layer with a thickness of 1-10μm, which covers the bottom bonding layer. The titanium or chromium bonding layer enhances the adhesion in the groove and avoids radio frequency delamination. The silver or copper main layer provides a low-resistance path.

[0036] A method for manufacturing a high-transmittance microstrip patch thin-film antenna, the method comprising the following steps:

[0037] S1: Two peelable transparent substrates 4 are bonded to the upper and lower surfaces of the transparent substrate 1 by hot pressing to form a three-layer composite structure. The thickness of the transparent substrate 4 is 5–10 μm. A single hot pressing replaces multiple bonding to eliminate interlayer bubbles or wrinkles and ensure the uniformity of dielectric constant. Raised metal grid lines are formed on the surface of the transparent substrate 1. The height of the metal grid lines is 1–8 μm and the line width is 3–5 μm.

[0038] S2: A dual-face alignment laser system is used to synchronously etch the composite structure. The upper laser head etches radiation unit grid grooves on the top substrate, and the lower laser head etches ground plane grid grooves on the bottom substrate. The etching depth penetrates the transparent substrate 4 and extends to 1–5 μm below the surface of the transparent substrate 1 to ensure the anchoring strength of the metal grid. The dual-face alignment laser system includes a laser device. Positioning holes with a diameter of 0.5 mm are set at the four corners of the composite substrate. The laser device is equipped with a coaxial CCD positioning camera. The upper and lower laser heads achieve alignment accuracy with the CCD camera through the positioning holes to avoid the deterioration of port isolation caused by misalignment of the radiation and the ground plane.

[0039] In this embodiment, a 355nm ultraviolet laser with a pulse frequency of 50kHz and an energy density of 2.5J / cm² was used. 2 Subpixel alignment with the CCD camera is achieved through a positioning hole with a diameter of 0.5mm, and the double-sided etching position deviation is ≤3μm;

[0040] S3: Conductive metal is deposited on the surface of the groove through vacuum sputtering process, so that the metal fills the groove and covers the surface of the transparent substrate 4. In the vacuum sputtering process, the metal layer inside the groove 11 and the metal layer on the outer plane of the groove 11 form a thickness difference through the etching depth difference. The metal thickness inside the groove 11 is 1.5-3 times the metal thickness outside the groove 11 to reduce the grid sheet resistance and reduce the surface metal coverage, thus balancing the light transmittance and conductivity.

[0041] The depth-to-width ratio of the groove depth to the line width is controlled between 0.3 and 1.7. If it is too shallow, the metal adhesion will be insufficient, and if it is too deep, the mechanical strength of the substrate will decrease. The balance between the metal anchoring strength and the light transmittance of the substrate is achieved.

[0042] In the vacuum sputtering process, in the embodiment of layered deposition control, the titanium or chromium layer uses a sputtering power of 100–150W, an argon pressure of 0.3Pa, and a deposition rate of 0.5nm / s to enhance the adhesion at the bottom of the groove; the silver or copper layer uses a sputtering power of 300–500W, an argon pressure of 0.5Pa, and a deposition rate of 5nm / s to achieve a metal thickness inside the groove that is twice that outside the groove.

[0043] S4: Peel off the transparent substrate 4, retaining the metal mesh structure embedded in the transparent substrate 1;

[0044] S5: Electroplating is applied to thicken the exposed metal mesh so that the metal layer thickness reaches 90-110% of the groove depth. Electroplating thickening precisely controls the metal volume, avoiding the decrease in light transmittance caused by excessive thickness, while meeting the high-frequency skin depth requirements.

[0045] In the embodiment of electroplating thickening, the electroplating solution formulation is as follows: for silver electroplating, 35 g / L potassium silver cyanide and 120 g / L potassium cyanide are used at a temperature of 25°C; for copper electroplating, 200 g / L copper sulfate, 50 g / L sulfuric acid, and 0.5 g / L PEG additive are used; the thickness is controlled at a current density of 1–2 A / dm. 2 The duration is 30–120 seconds.

[0046] The surface of the metal mesh structure is coated with a transparent insulating layer made of UV-curable fluorinated acrylic resin with a refractive index matching the substrate and a thickness of 0.5–2 μm. This layer covers the metal mesh and fills the gaps between the meshes, smoothing the surface and reducing haze caused by optical diffraction. The transparent insulating layer isolates the environment from water and oxygen, improving the weather resistance of the flexible antenna.

[0047] In summary, this solution utilizes a groove-embedded metal mesh structure and complementary topology design to maintain a solid mesh in the radiating unit to ensure RF performance, while reducing the metal light-shielding area by hollowing out the ground plane. Combined with the metal thickness gradient formed by the groove depth difference, it significantly optimizes the synergy between transmittance and sheet resistance in the visible light band.

[0048] The double-sided alignment laser system is used to achieve alignment accuracy, which fundamentally suppresses the problem of port isolation deterioration caused by pattern misalignment. The process of single hot-pressing composite can peel off the sacrificial layer substrate, completely avoiding bubbles, wrinkles and dielectric constant non-uniformity caused by multiple bonding.

[0049] The design of the groove extending 1–5 μm into the substrate, combined with a titanium or chromium bonding layer, enhances the adhesion stability of the metal mesh under flexible bending; the end electroplating precisely controls the metal volume and the transparent insulating coating covers it, simultaneously achieving the requirements of high-frequency conductivity and optical surface flatness.

[0050] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-transmittance microstrip patch antenna, comprising a transparent substrate (1), characterized in that: One side of the transparent substrate (1) is provided with a radiation unit metal mesh layer (2), and the other side of the transparent substrate (1) is provided with a ground plane metal mesh layer (3). Grooves (11) are provided on both the upper and lower surfaces of the transparent substrate (1). The grooves (11) are filled with conductive metal to form a conductive metal layer (5). The radiation unit metal mesh layer (2) and the ground plane metal mesh layer (3) are both embedded in the grooves (31).

2. The high-transmittance microstrip patch antenna according to claim 1, characterized in that: The transparent substrate (1) is a flexible transparent polymer film with a thickness of 50-200μm, and is made of polyethylene terephthalate, cyclic olefin polymer, and transparent polyimide transparent substrate.

3. The high-transmittance microstrip patch antenna according to claim 1, characterized in that: The radiating unit metal mesh layer (2) and the grounding plate metal mesh layer (3) adopt a complementary topology structure. The radiating unit is a solid mesh frame and the grounding plate is a hollow mesh.

4. The high-transmittance microstrip patch antenna according to claim 1, characterized in that: The conductive metal layer (5) is composed of a bottom bonding layer and a main conductive layer. The bottom bonding layer is a titanium or chromium layer with a thickness of 0.1-0.5μm, which directly contacts the bottom surface of the groove (11). The main conductive layer is a silver or copper layer with a thickness of 1-10μm, which covers the bottom bonding layer.

5. A method for manufacturing a high-transmittance microstrip patch thin-film antenna, characterized in that: The manufacturing method, applied to the high-transmittance microstrip patch thin-film antenna as described in any one of claims 1-4, includes the following steps: S1: Two peelable transparent substrates (4) are bonded to the upper and lower surfaces of the transparent substrate (1) by hot pressing to form a three-layer composite structure. The thickness of the transparent substrate (4) is 5–10 μm. S2: A composite structure is synchronously etched using a dual-face aligned laser system. The upper laser head etches a radiation unit grid groove on the top substrate, and the lower laser head etches a ground plane grid groove on the bottom substrate. The etching depth penetrates the transparent substrate (4) and extends to 1–5 μm below the surface of the transparent substrate (1). S3: Conductive metal is deposited on the groove surface by vacuum sputtering process, so that the metal fills the groove and covers the surface of the transparent substrate (4); S4: Peel off the transparent substrate (4), retaining the metal mesh structure embedded in the transparent substrate (1); S5: Electroplating is applied to thicken the exposed metal mesh so that the metal layer thickness reaches 90–110% of the groove depth.

6. The method for manufacturing a high-transmittance microstrip patch thin-film antenna according to claim 5, characterized in that: The dual-sided alignment laser system includes a laser device, and the composite substrate has positioning holes at its four corners with a diameter of 0.5 mm; the laser device is equipped with a coaxial CCD positioning camera.

7. The method for manufacturing a high-transmittance microstrip patch thin-film antenna according to claim 5, characterized in that: In the vacuum sputtering process, the metal layer inside the groove (11) and the metal layer on the outer plane of the groove (11) form a thickness difference through the difference in etching depth. The metal thickness inside the groove (11) is 1.5–3 times the metal thickness outside the groove (11).

8. The method for manufacturing a high-transmittance microstrip patch thin-film antenna according to claim 5, characterized in that: The transparent substrate (1) has raised metal mesh lines on its surface, with a height of 1–8 μm and a line width of 3–5 μm.

9. The method for manufacturing a high-transmittance microstrip patch thin-film antenna according to claim 5, characterized in that: The surface of the metal mesh structure is coated with a transparent insulating layer with a thickness of 0.5–2 μm, which covers the metal mesh and fills the mesh gaps.

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