Patent Publication Number: US-2013240252-A1

Title: 3d-shaped component with a circuit trace pattern and method for making the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority of U.S. Patent Provisional Application No. 61/612589, filed on Mar. 19, 2012. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a 3D-shaped component with a circuit trace pattern and a method for making the same, more particularly to a 3D-shaped component having a 3D-shaped plastic film and a circuit trace pattern embedded in the 3D-shaped plastic film. 
     2. Description of the Related Art 
     Conventional touch sensors having a circuit trace pattern can be formed by coating an indium-tin-oxide (ITO) layer on a plastic substrate, followed by photolithography of the ITO layer. However, since the ITO layer is very brittle and cannot be bent, it is not possible to form ITO trace elements on a flat substrate and then bend the ITO trace elements and the substrate to form a desired three dimensional-shaped (3D-shaped) component with curved ITO trace elements. In addition, the ITO layer is normally formed using sputtering techniques, which is under a temperature that is too high for most plastic substrates. Conventional touch sensors can also be made from a flexible printed circuit board. However, the flexible printed circuit board is expensive, and assembling the flexible printed circuit board with a plastic substrate increases the overall thickness of the 3D-shaped component. Neither the ITO layer on a substrate nor the flexible printed circuit board is suitable for use in making a 3D-shaped component with curved circuit trace elements. 
     U.S. Patent Application Publication No. 2008/0074330 discloses an electronic apparatus with an antenna and an anti-jamming system. The electronic apparatus comprises a casing and the antenna. The antenna is composed of a patterned metal thin film and a carrier, and is provided for processing a wireless signal. Combination of the casing and the antenna is conducted by injection molding. When the electronic apparatus is a display device, the anti-jamming system can modulate a clock signal generated by the display device to prevent the multiplication of the clock signal from interfering with signals within an operating band of the antenna. 
     U.S. Pat. No. 7,977,953 discloses an in-mold molding touch module including a plastic film, a touch circuit and a molding rind. The plastic film includes an inner surface and an outer surface for handling and touching. At least one region of the inner surface and a corresponding region of the outer surface cooperatively define a touch area. The touch circuit is arranged on the inner surface in the touch area. The molding rind is integrated on the inner surface by an in-mold injection mode to contain the touch circuit for forming a one-piece body. 
     People&#39;s Republic of China Patent Publication No. CN101587980 discloses a method for forming an antenna on a shell by inject ion-molding techniques. The method includes the steps of: coating a conductive ink on a plastic flint to form an antenna thereon; pressing and cutting an assembly of the plastic film and the antenna to form a feature unit; placing the feature unit in an injection molding machine; and injection molding a plastic material over the feature unit so as to form a shell directly on the feature unit. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a 3D-shaped component with a circuit trace pattern and a method for making the same that is simple and cost effective. 
     According to one aspect of the present invention, there is provided a 3D-shaped component with a circuit trace pattern. The 3D-shaped component comprises: a 3D-shaped plastic film having a surface; and a circuit trace pattern disposed at the surface of the 3D-shaped plastic film, embedded in the 3D-shaped plastic film, and made from a cured conductive ink. 
     According to another aspect of the pre sent invention, there is provided a method for making a 3D-shaped component having a circuit trace pattern. The method comprises: printing a circuit trace pattern of a curable conductive ink on a flat plastic film; curing the curable conductive ink on the flat plastic film; placing the flat plastic film together with the circuit trace pattern of the cured conductive ink in a mold cavity; softening the flat plastic film in the mold cavity by heating; and deforming the softened flat plastic film to the shape of the mold cavity by applying pressure to the softened flat plastic film so as to form a 3D-shaped plastic film with the circuit trace pattern. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
       In drawings which illustrate embodiments of the invention, 
         FIG. 1  is a schematic view of the first preferred embodiment of a 3D-shaped component with a circuit trace pattern according to the present invention; 
         FIGS. 2 to 5  are schematic views illustrating consecutive steps of a method of making the first preferred embodiment; 
         FIG. 6  is a schematic view of the second preferred embodiment of a 3D-shaped component with a circuit trace pattern according to the present invention; 
         FIG. 7  is a schematic view of the third preferred embodiment of a 3D-shaped component with a circuit trace pattern according to the present invention; and 
         FIG. 8  is a schematic view of the fourth preferred embodiment of a 3D-shaped component with a circuit trace pattern according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     Before the present invention is described in greater detail with reference to the accompanying preferred embodiments, it should be noted herein that like elements are denoted by the same reference numerals throughout the disclosure. 
       FIG. 1  illustrates the first preferred embodiment of a 3D-shaped component  2  for an electronic device, such as a mobile phone or a notebook computer, according to the present invention. The 3D-shaped component  2  can be a touch sensitive housing to provide touch function or can be a housing with a built-in antenna. The 3D-shaped component  2  includes: a 3D-shaped plastic film  21  having a first surface  211  and a second surface  212  opposite to the first surface  211 ; and a circuit trace pattern  22  that is disposed at the first surface  211  of the 3D-shaped plastic film  21 , that is embedded in the 3D-shaped plastic film.  21 , and that is made from a cured conductive ink. 
     The 3D-shaped plastic film  21  has a generally bow-shaped cross-section, The first surface  211  of the 3D-plastic film  21  has two opposite curved regions  211   a . The circuit trace pattern  22  has a plurality of conductive trace elements  221  (only two trace elements  221  are shown for the sake of clarity) that are spaced apart from one another, that are disposed at the curved regions  211   a  of the first surface  211  of the 3D-shaped plastic film  21 , respectively, and that are curved in shape. 
     Preferably, the 3D-shaped plastic film  21  is made from a material selected from polycarbonate (PC), polymethylmethacrylate (PMMA), and polyethylene terephthalate (PET). 
     The cured conductive ink is made from a curable conductive ink including an electrically conductive material and a UV or heat curable resin. 
       FIGS. 2 to 5  illustrate consecutive steps of a method of making the first preferred embodiment of the 3D-shaped component  2 . The method includes: printing a circuit trace pattern  22  of a curable conductive ink on a peripheral region of a flat plastic film  21 ′ (see  FIG. 2 ), the circuit trace pattern  22  having a plurality of conductive trace elements  221 ; curing the curable conductive ink on the flat plastic film  21 ′ using a UV light (see  FIG. 3 ); placing the flat plastic film  21 ′ together with the circuit trace pattern  22  of the cured conductive ink in a mold cavity  50  in a mold  5  (see  FIGS. 4 and 5 ); softening the flat plastic film  21 ′ in the mold cavity  50  by heating; deforming the softened flat plastic film  21 ′ to the shape of the mold cavity  50  by applying a pressure (P) to the softened flat plastic film  21 ′ so as to form the 3D-shaped component  2  including the 3D-shaped plastic film  21  and the circuit trace pattern  22  embedded in the 3D-shaped plastic film  21  (see  FIG. 5 ); and cooling and removing the 3D-shaped component  2  from the mold  5  (see  FIG. 1 ). During the deformation of the softened flat plastic film  21 ′ to the shape of the mold cavity  50 , the peripheral region of the flat plastic film  21 ′ is curvedly deformed and the trace elements  221  of the circuit trace pattern  22  on the peripheral region are curvedly deformed as well. Therefore, the method of the present invention is capable of forming a circuit trace pattern on a curved surface to thereby facilitate the design of the electronic device and the utilization of space in the electronic device so as to reduce the dimensions of the electronic device. 
     The printing of the curable conductive ink on the flat plastic film  21 ′ to form the circuit trace pattern  22  can be conducted by screen printing, digital printing, pad printing, and offset printing. The curable ink employed can be transparent or have a silver color. 
       FIG. 6  illustrates the second preferred embodiment of the 3D-shaped component  2  according to the present invention. The second preferred embodiment differs from the first preferred embodiment in that the 3D-shaped component  2  further includes a 3D-shaped plastic feature part  23  that is molded over the first surface  211  of the 3D-shaped plastic film  21  and that covers at least a portion of the circuit trace pattern  22 . The 3D-shaped plastic film  21  has a thickness less than that of the plastic feature part  23 . Formation of the plastic feature part  23  on the 3D-shaped plastic film  21  is conducted by In-Mold Forming (IMF) techniques by placing the 3D-shaped plastic film  21  together with the circuit trace pattern  22  in an injection mold (not shown), followed by injecting a molten resin into the injection mold. 
     Preferably, the plastic feature part  23  is made from, a resin selected from polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS), polymethyl-methacrylate (PMHA), and combinations thereof. 
     Preferably, formation of the plastic feature part  23  is conducted by IMF techniques using one of the aforementioned resins as the raw material under a mold temperature ranging from 80° C. to 90° C. When the mold temperature is less than 80° C., an undesired pattern shifting or deformation of the circuit trace pattern  22  by the flow of a molten resin occurs during injection of the molten resin in the injection mold, and when the mold temperature is greater than 90° C., the 3D-shaped plastic film  21  cannot withstand the mold temperature, which can cause an undesired film warping problem. 
       FIG. 7  illustrates the third preferred embodiment of the 3D-shaped component  2  according to the present invention. The third preferred embodiment differs from the second preferred embodiment in that the plastic feature part  23  is molded over the second surface  212  of the 3D-shaped plastic film  21 . 
       FIG. 8  illustrates the fourth preferred embodiment of the 3D-shaped component  2  according to the present invention. The fourth preferred embodiment differs from the first preferred embodiment in that the 3D-shaped plastic film  21  is generally arcuate in shape. 
     By printing the curable conductive ink on the flat plastic film  21 ′ and softening and deforming the flat plastic film  21 ′ to the shape of the mold cavity SO according to the method of this invention, a 3D-shaped plastic film  21  with a circuit trace pattern  22  formed on a curved region  211   a  of the first surface  211  of the 3D-plastic film  21  can be formed and the aforesaid drawbacks associated with the use of the ITO layer on a substrate or the flexible printed circuit board for forming the 3D-shaped component can be overcome. In addition, since the circuit trace pattern  22  is embedded in the 3D-shaped plastic film  21  by virtue of the softening of the flat plastic film  21 ′ during the deforming process, the overall thickness of the 3D-shaped component  2  is reduced. Moreover, by controlling the mold temperature to foe within the range of from 80° C. to 90° C., the aforesaid pattern shifting or deformation of the circuit trace pattern  22  during injection of the molten resin for forming the plastic feature part  23  over the first surface  211  of the 3D-shaped plastic film  21  and the circuit trace pattern  22  can be alleviated. 
     While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.