Patent Publication Number: US-2019191556-A1

Title: Circuit board with a substrate made of silicon

Description:
The present invention is a divisional application of U.S. patent application Ser. No. 15/841,313, filed at Dec. 14, 2017, which is invented by and assigned to the applicant of the present invention, and thus the contents of the U.S. patent application Ser. No. 15/841,313 is incorporated into the present invention as a part of the present invention. 
    
    
     FIELD OF INVENTION 
     The present invention relates to circuit board materials, and in particular to a circuit board with a substrate made of silicon. 
     BACKGROUND OF THE INVENTION 
     As shown in  FIG. 1 , the conventional printed circuit is made of PET or PI boards (films) which is made as a substrate  10 ′. Then a metal layer  30 ′ is adhered to the substrate  10 ′ by using an adhesive layer  20 ′. Material of the metal layer  30 ′ is selected from copper, silver, gold, etc. If packaging is necessary, silicon  40 ′ is added to the printed circuit. 
     Generally, printed circuits are classified as hard boards and soft boards. The hard boards are made of FR4, aluminum, or ceramics. The soft boards are made of PET, PI, etc. The structure of soft boards has some defects in practical usages. The main reasons are that PET or PI are not usable in high temperatures over 130° C. This high temperature will induce deformation of the circuit or the electric properties of the elements on the circuit boards are shifted, for example, impedances are changed so that precise data transfer cannot be achieved. 
     The extension property of PET or PI is not preferable. In many applications, for example, biological chips, these circuit boards are not suitable due to bad extension property. Furthermore PET or PI boards are not compactable biologically. The boards are easily reacted with peripheral organs biologically. 
     Therefore, the present invention desired to provide a novel invention which can improve above mentioned defects. 
     SUMMARY OF THE INVENTION 
     To improve above object, the present invention provides a circuit board with a substrate made of silicon, wherein a silicon substrate is used to replace conventional substrates which use PET or PI. The silicon is more extensible and flexible than the prior art PET substrate. Furthermore silicon substrate is bendable so that it is suitable for forming bendable circuit board. Silicon has low dielectric coefficient which is suitable as substrates for antennas or other wireless circuits. Furthermore, the temperature tolerance of silicon substrate is over 200 degree C. so that the present invention is usable in high temperatures, such as medical usages. Generally, high temperature sterilization is over 160 degrees, but the conventional PET or PI substrates cannot be used under such temperatures. Moreover, the silicon substrate  10  is water proof and heat tolerant so that they can be used in various environments and thus productions of silicon substrates are easily. Further, silicon substrates are difficult to react chemically with other biological organs, and thus they are suitable in applications of biologics, such as forming as biological chips. 
     To achieve above object, a circuit board with a substrate made of silicon is provided, which comprises a silicon substrate made of silicon; an adhering layer which is a gluing layer and is adhered on the silicon substrate; a metal layer formed as a metal plate layer or a metal circuit layer; the metal layer being adhered on the adhering layer; and wherein the metal layer is etched to form with metal circuits. Furthermore, electronic elements are adhered on the metal layer to form as circuits with specific functions. A packaging silicon layer encapsulates the metal layer and the electronic elements for packaging. The circuit board is a flat plate board or a curled board. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross sectional view of a prior art printed circuit board. 
         FIG. 2A  shows a schematic cross section view of the present invention. 
         FIG. 2B  is a perspective schematic view of the present invention. 
         FIG. 3  shows the manufacturing process of the present invention. 
         FIG. 4  is a schematic view showing the etching process of the present invention. 
         FIG. 5  is a flow diagram about the manufacturing method when the present invention is applied to screen printing. 
         FIG. 6  is a schematic view which shows that the present invention is applied to screen printing. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In order that those skilled in the art can further understand the present invention, a description will be provided in the following in details. However, these descriptions and the appended drawings are only used to cause those skilled in the art to understand the objects, features, and characteristics of the present invention, but not to be used to confine the scope and spirit of the present invention defined in the appended claims. 
     With reference to  FIGS. 2A to 4 , the structures of the present invention are shown. The present invention is related to a circuit board with a substrate made of silicon which includes following elements. 
     A silicon substrate  10  (With reference to  FIGS. 2A and 2B ) is made of silicon which is more extensible and flexible than PET substrate. Furthermore, silicon is tolerable with temperatures higher than 200° C. 
     An adhering layer  20  is adhered on the silicon substrate  10 . Materials of the adhering layer  20  contains Organic silicon polyester copolymer resin, Ethyl acetate and Organic silicon resin. 
     A metal layer  30  is formed as a metal plate layer or a metal circuit layer. If the metal layer  30  is formed as a metal plate layer, it can be formed as circuits by etching or screen printing. The metal layer  30  is adhered on the adhering layer  20 . Material of the metal layer  30  is selected from metals such as copper, aluminum, sliver, gold, etc. 
     Practically, other electronic elements  35  may be arranged on the metal layer  30  (as shown in the schematic view of  FIG. 2 ) so as to form as a functional circuit. 
     If in packaging, a packaging silicon layer  40  encapsulates the metal layer  30  (maybe including the electronic elements  35  thereon) for packaging the metal layer  30  and the electronic elements  35  thereon. 
     With reference to  FIGS. 3 and 4 , a manufacturing process for forming an etching circuit board on the silicon substrate is illustrated. The process will be described herein. The process comprises the following step of: 
     Preparing metal layer  30  for forming a circuit; and guiding the metal layer  30  to a coating unit  110 ; and coating glue material on the metal layer  30  so as to form with a gluing layer  20  (step  802 ); 
     Guiding the metal layer  30  with the gluing layer  20  to a first baking unit  121  for baking (step  804 ); Spraying silicon material from a silicon material barrel  100  into a space between two rollers  1 ; wherein the rollers will compress and roll the silicon material to be form as a silicon substrate  10  with a predetermined width (step  806 ); 
     By the two rollers  2  and a transferring belt  200 , guiding the silicon substrate  10  to a metal adhering unit  130 , and meanwhile guiding the metal layer  30  with the gluing layer  20  to the metal adhering unit  130 ; adhering the gluing layer  20  of metal layer  30  to the silicon substrate  10  so as to form as a compound board  50  which serves to be formed as a circuit board (step  810 ); Guiding the compound board  50  to a second baking unit  122  for baking the compound board  50  (step  820 ); 
     In the present invention, the compound board  50  may be a plate like structure or be curled for storage or transferring. If necessary, the curled compound board  50  can be straightened for forming circuits or packaging in the succeeding process. 
     Next, transferring the baked compound board  50  to an etching tank  140  for etching (step  840 ); wherein liquid for etching may be alkaline or acidic, for example, copper chloride. 
     Next, forming circuit on the etched compound board  50  (step  850 ); these steps are known in the arts, and thus the details will not be further described herein. 
     If packaging is necessary, the functional circuit  37  formed by electronic elements  35  on the metal layer  30  is packaged with a packaging silicon layer  40  by using a packaging device  150  (step  850 ). 
     With reference to  FIGS. 5 and 6 , the process for forming printed circuit board on the silicon substrate will be described herein. 
     Spraying silicon material from a silicon material barrel  100  into a space between two rollers  1 ; wherein the rollers will compress and roll the silicon material to be form as a silicon substrate  10  with a predetermined width (step  906 ); 
     By the two rollers  2  and a transferring belt  200 , guiding the silicon substrate  10  to a gluing material coating unit  110 , and then gluing material is coated on the silicon substrate  10  so as to form a gluing layer  20  (step  907 ); Guiding the silicon substrate  10  with the gluing layer  20  to a first baking unit  121  for baking the silicon substrate  10  with the gluing layer  20  (step  908 ) 
     Then guiding the baked silicon substrate  10  with the gluing layer  20  to a screen printing plate adding unit  160  so as to adhere a screen plate  161  on the gluing layer  20  to form with an integrated board  60 ; wherein the screen plate  161  has hollowed areas  165  for forming circuits in the succeeding process (step  909 ) 
     Next transferring the integrated board  60  to an ink unit  170  to add metal ink on the hollowed areas of the screen plate  161 ; and then taking out the screen plate  161  and the left metal inks  171  are formed as a metal layer  30  which is a printed circuit. In that, the metal layer  30 , the silicon substrate  10  and the gluing layer  20  are formed as a compound board  50  (step  910 ). The metal inks  181  are selected from metal materials, such as copper, aluminum, silver, gold, etc. 
     Guiding the compound board  50  to a second baking unit  122  for baking the compound board  50  (step  911 ) 
     If packaging is necessary, other electronic elements  35  are installed or formed on the metal layer  30  (those shown on the drawings are only schematic views) to form as a functional circuit  37 ; then a packaging machine  150  forms a packaging layer  40  on the compound board  50  (step  912 ). 
     In the present invention, a silicon substrate is used to replace conventional substrates which use PET or PI. The silicon is more extensible and flexible than the prior art PET substrate. Furthermore silicon substrate is bendable so that it is suitable for forming bendable circuit board. Silicon has low dielectric coefficient which is suitable as substrates for antennas or other wireless circuits. Furthermore, the temperature tolerance of silicon substrate is over 200 degree C. so that the present invention is usable in high temperatures, such as medical usages. Generally, high temperature sterilization is over 160 degrees, but the conventional PET or PI substrates cannot be used under such temperatures. Moreover, the silicon substrate  10  is water proof and heat tolerant so that they can be used in various environments and thus productions of silicon substrates are easily. Further, silicon substrates are difficult to react chemically with other biological organs, and thus they are suitable in applications of biologics, such as forming as biological chips. 
     The present invention is thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.