Patent Application
20130120196
1. Technical Field
The present disclosure relates to antennas and a method for making the antennas.
2. Description of Related Art
A typical antenna for an electronic device is usually a patterned copper sheet integral with a laminate manufactured to be further integrated with a plastic housing by a conventional insert molding labeling method. However, the patterned copper sheet typically has a thickness exceeding 0.3 millimeters (mm), increasing the thickness and size of the molded housing.
Therefore, there is room for improvement within the art.
Many aspects of the disclosure can be better understood with reference to the following figures. The components in the figures are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the disclosure.
The substrate 12 may be made of a transparent plastic, such as polycarbonate (PC) or polymethyl methacrylate (PMMA). The substrate 12 may also be made of transparent glass. In an exemplary embodiment, the substrate 11 is made of polymethyl methacrylate. The substrate 12 may be a display window for electronic devices. Also, the substrate 12 may be a front windshield for vehicles.
The silver layer 14 is formed on a surface 120 of the substrate 12, providing a desired antenna pattern on the substrate 12. Referring to
The ink layer 16 may cover the feed portion 141 and the grounding portion 143. The ink layer 16 may be made of an electroconductive ink mainly comprising organic polymer and electroconductive substance. The organic polymer can be a copolymer resin of chlorinated alkene, alkene acetate, and methacrylic hydroxyl. The electroconductive substance may be micron-sized silver powder or copper wrapped silver powder. The ink layer 16 may have a thickness of about 1 μm to about 50 μm, with a transmission of visible light greater than 85%. The ink layer 16 may protect the feed portion 141 and the grounding portion 143 from oxidization by ambient environmental conditions. Moreover, the ink layer 16 is electroconductive and therefore does not influence electrical connections between the feed portion 141, the grounding portion 143, and the circuit board.
The protective layer 18 may cover the entire silver layer 14 except the feed portion 141 and the grounding portion 143. The protective layer 18 is transparent and may be made of transparent resin paint, such as ultraviolet curable resin paint. In one exemplary embodiment, the protective layer 18 is made of an acrylic polyurethane paint. The thickness of the protective layer 18 may be about 5 μm to about 25 μm. The protective layer 18 may protect corresponding portions of the silver layer 14 (the feed portion 141 and the grounding portion 143 not included) from oxidization caused by contacting with air.
The antenna 10 (including the substrate 12) has an average transmission of visible light greater than 40%. In case of a substrate 12 made of PMMA, the transmission of light with a wavelength of about 550 nm of the antenna is about 45% to about 55%.
If the thickness of the silver layer 14 is greater than 25 nm, the average transmission of visible light of the antenna 10 is lower than 40%. When the thickness of the silver layer 14 is less than 5 nm, the sheet resistance of the silver layer 14 is greater than 2.1 Ω/sq. Thus, the electric conductivity of the antenna 10 can be greatly decreased.
An exemplary method for making the antenna 10 may include the following steps.
The substrate 12 is provided.
The substrate 12 may be cleaned to remove impurities such as grease or dirt from the substrate 12. Then, the substrate 12 is dried.
A desired antenna pattern is formed on the substrate 12 using a silver layer 14. The silver layer 14 has the feed portion 141 and the grounding portion 143. The silver layer 14 may partially cover the substrate 12. Forming the silver layer 14 may include the following steps:
The substrate 12 is masked using a first masking film (not shown). The first masking film has an opening. The opening has a shape of the desired antenna pattern.
A vacuum sputtering process is applied on the substrate 12 with the first masking film, forming the silver layer 14 on the substrate 12. The silver layer 14 may initially cover the first masking film and portions of the substrate 12 exposed from the opening of the first masking film. The vacuum sputtering process is implemented in a chamber of a conventional sputtering machine (not shown). The substrate 12 masked using the first masking film is held on a rotating bracket in the chamber. The speed of the rotating bracket is between about 2.5 revolutions per minute (rpm) and about 3.5 rpm. The chamber is evacuated to maintain an internal pressure in a range from about 6.5×10−3 Pa to about 9.5×10−3 Pa and the inside of chamber maintains a temperature between about 15° C. and about 55° C. Argon may be fed into the chamber as a sputtering gas. The argon may create a partial pressure of about 0.2 Pa to about 0.6 Pa in the chamber. About 1.0 kW-4.0 kW of power is applied to a silver target fixed in the chamber, depositing the silver layer 14 as an electroconductive layer. The deposition of the silver layer 14 may take about 15 seconds to about 45 seconds. The silver layer 14 has a thickness of about 5 nm to about 25 nm.
The first masking film and portions of the silver layer 14 formed on the first masking film are removed, the remainder of the silver layer 14 covering the substrate 12 forming a desired antenna pattern.
The protective layer 18 is formed on the silver layer 14. The protective layer 18 covers the entire silver layer 14 except the feed portion 141 and the grounding portion 143. Forming the protective layer 18 may include the following step. The feed portion 141 and the grounding portion 143 are masked using a second masking film (not shown). The substrate 12 with the silver layer 14 is sprayed with a transparent resin paint layer. The transparent resin paint layer covers at least the silver layer 14 and the second masking film. The second masking film and portions of the transparent resin paint layer formed thereon are removed, the remainder of the transparent resin paint layer forming the protective layer 18.
The ink layer 16 may be formed on the feed portion 141 and the grounding portion 143 by printing, for example.
The first masking film and the second masking film may be adhesive tape.
The total thickness of the antenna 10 is small and the visible light transmissible capability is also high. Thus, the antenna 10 can be mounted on transparent members without occupying much space, such as display windows of electronic devices and front windshields of vehicles.
It is believed that the exemplary embodiment and its advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its advantages, the examples hereinbefore described merely being preferred or exemplary embodiment of the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201110356854.X | Nov 2011 | CN | national |
