Patent Publication Number: US-2011056614-A1

Title: Manufacturing method of circuit board

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 10-2009-0085385 with the Korean Intellectual Property Office on Sep. 10, 2009, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a manufacturing method of a circuit board. 
     2. Description of the Related Art 
     Recently, the size of electronic components for electronic devices gets smaller. Accordingly, the size of package of a device chip also gets smaller. This requires thinner circuit boards for the package. Meanwhile, to minimize the loop inductance originated by physical distance of circuitry, thinner circuit boards are required. 
     According to today&#39;s trend that circuit boards get thinner, there is an increasing demand for coreless substrates which omit the core in the circuit board. 
     Since the coreless substrate has a structure of low stiffness, stiffeners are used for reinforcement. Accordingly, because a process for implementing the stiffeners on the circuit board is needed, additional manufacturing cost and time are consumed. 
     SUMMARY 
     The present invention provides a manufacturing method of circuit board that can easily form stiffeners on circuit board. 
     One aspect of the invention provides a manufacturing method of a circuit board. The manufacturing method of a printed circuit board in accordance with an embodiment of the present invention can include: forming a separation layer on a carrier; stacking an adhesion layer which is coupled to the carrier and covers the separation layer; forming a circuit layer on the adhesion layer; forming a circuit board unit by cutting the separation layer, the adhesion layer and the circuit layer such that the separation layer is separated from the carrier; and forming a stiffener by processing the separation layer of the circuit board unit. 
     Here, the forming of a separation layer can include stacking a metal plate on the carrier. 
     The forming of a separation layer can also include forming a demolding layer on the carrier before the stacking of a metal plate. 
     The method can also include forming a reinforcement layer on the circuit layer and forming a stiffener by processing the reinforcement layer. 
     The forming of a reinforcement layer can include applying a solder resist on the circuit layer and stacking a metal plate on the solder resist by vacuum lamination. 
     The method can also include forming a plating protection layer on the stiffener. 
     The forming of the plating protection layer can include forming an oxidized film on the stiffener. 
     The forming of the oxidized film can include anodizing the stiffener. 
     Here, the stiffener can include aluminum, and the anodizing of the stiffener can include forming an aluminum oxide by anodizing the aluminum stiffener. 
     The forming of a plating protection layer can include forming the plating protection layer by applying an insulation material on the stiffener. 
     The forming of a plating protection layer can include forming an OSP (Organic Solderability Preservative) coating layer on the stiffener. 
     Additional aspects and advantages of the present invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a flow chart of a manufacturing method of a circuit board according to an embodiment of the invention. 
         FIG. 2  through  FIG. 9  illustrate sectional views showing processes of a manufacturing method of a circuit board according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     An embodiment of the present invention will be described below in more detail with reference to the accompanying drawings. 
       FIG. 1  is a flow chart of a manufacturing method of a circuit board according to an embodiment of the invention, and  FIG. 2  through  FIG. 9  illustrate sectional views showing processes of a manufacturing method of a circuit board according to an embodiment of the invention. 
     The manufacturing method of a circuit board in accordance with an embodiment of the present invention includes forming a separation layer (S  110 ), stacking an adhesion layer (S 120 ), forming a circuit layer (S 130 ), forming a circuit board unit (S 140 ) and forming a stiffener (S 150 ). Also, it can further include forming a plating protection layer (S 160 ) 
     A separation layer  20  is formed on a carrier  10  in forming a separation layer (S 110 ). The carrier  10  is a part supporting an in-process product of the circuit board in the manufacturing process, and the separation layer  20  is a part which is not connected to the carrier  10  but stacked on the carrier  10  only to easily separate the in-process product of circuit board from the carrier  10 . 
     Here, the carrier  10  can be composed of insulation material. Because the difference in thermal expansion coefficient between the carrier  10  composed of insulation material and the circuit board formed above the carrier  10  is small, the carrier  10  can prevent damages which are resulted from thermal deformation in the process. Also, the carrier  10  can include a metal layer  12 . The metal layer costs less and can be recycled with limited damages in a cutting process described below. 
     Moreover, the separation layer  20  is formed by stacking a metal plate on the carrier  10  (S 115 ). The metal plate used as the separation layer  20  can be easily produced by an etching process in forming a stiffener (S 150 ). 
     As illustrated in  FIG. 2 , the carrier  10  which is formed by stacking the metal layer  14  on the insulation layer  12  is used in this embodiment. Also, the separation layer  20  is formed by stacking the metal plate on the metal layer  14  of the carrier  10 . Here, for the purpose of easy separation between the metal layer  14  and the metal plate in the separation process of the separation layer described below, a demolding layer can be formed on the carrier  10  before stacking the metal plate constituting the separation layer  20 . 
     Subsequently, an adhesion layer  30 , which is coupled to the carrier  10  and covers the separation layer  20 , is stacked on the carrier  10  in stacking the adhesion layer (S 120 ). As illustrates in  FIG. 3 , the adhesion layer  30 , which covers the separation layer  20  and is stacked, is coupled at the area of the carrier  10 , which is not covered by the separation layer  20 . Accordingly, the in-process product, which is stacked on the separation layer  20  and the adhesion layer  30 , is firmly supported by the carrier  10 . 
     In this embodiment, the adhesion layer  30  is formed by applying an insulation material on the carrier  10  on which the separation layer is stacked. 
     Subsequently, a circuit layer  40  is formed on the adhesion layer  30  in forming a circuit layer (S 130 ). 
     As illustrated in  FIG. 4 , a multi-layered circuit layer  40  is formed on the insulation layer used as the adhesion layer  30  by using the Build-Up process in this embodiment. 
     At this time, as illustrated in  FIG. 5 , a reinforcement layer  60  can be further formed on the circuit layer  40  in order to form stiffeners  25 ,  26  on both sides of the circuit board. The reinforcement layer  60  can be used as a stiffener  65  in the subsequent process. In this embodiment, the reinforcement layer  60  is formed by stacking a metal plate. 
     Here, the stack of the reinforcement layer  60  can be formed in company with forming a solder resist layer  50 . Specifically, after applying the solder resist on the circuit layer  40 , the metal layer can be coupled to the solder resist layer  50  by laminating the metal plate with vacuum press. 
     Subsequently, a circuit board unit is formed by cutting the separation layer  20 , the adhesion layer  30  and the circuit layer  40  to separate the separation layer  20  from the carrier  10  in forming a circuit board unit (S 140 ). Because the carrier  10  is not needed in a finished circuit board, the circuit board unit is formed by separating the circuit layer  40  from the carrier  10  after forming major parts of the circuit board. 
     Specifically, the unit of circuit board and carrier  10  are separated by separating the separation layer  20  of the unit of circuit board from the carrier  10 . In order to do this, as illustrated in  FIG. 6 , the separation layer  20  and the adhesion layer  30  and the circuit layer  40 , which are formed on the separation layer  20 , are cut. Since the carrier  10  and the separation layer  20  are not coupled, as illustrated in  FIG. 7 , the circuit board unit can be separated from the carrier  10  along the separation layer  20 . In this embodiment, the separation layer  20 , the adhesion layer  30  and the circuit layer  40 , which are stacked on the carrier  10 , are cut through a routing process. 
     Subsequently, a stiffener  25  is formed by processing the separation layer  20  of the circuit board unit and utilizing the separation layer  20  in forming a stiffener (S 150 ). Accordingly, the manufacturing cost and manufacturing time are reduced because the stiffener  25  is formed together in the processing of the circuit board. 
     As illustrated in  FIG. 8 , the stiffener  25  is formed by processing the metal plate used as the separation layer  20  with an etching process in this embodiment. In this time, the stiffeners  25 ,  65  can be formed on both sides of the circuit board unit together by processing the metal plate used as the reinforcement layer  60  with the etching process. 
     The stiffeners  25 ,  65  are formed by processing the metal plate in this embodiment. Accordingly, the waste of the plating plate may occur due to the plating of the expensive plating plate on the stiffeners  25 ,  65  in the subsequent forming of an electrode pad. 
     For the purpose of preventing this, as illustrated in  FIG. 9 , a plating protection layer  70  is formed on the stiffeners  25 ,  65  in forming a plating protection layer (S 160 ). 
     Specifically, forming an oxidized film on the stiffeners  25 ,  65  in this embodiment can prevent plating (S 165 ). Here, the oxidized film can be formed by anodizing, i.e. anodic oxidation. Anodic oxidation is the method that can connect a metal to an anode, which sinks under an electrolyte, and oxidize the surface of the metal by oxygen generated from the anode. Since the oxidized film formed on the surface of the stiffeners  25 ,  65  by anodic oxidation has lower conductivity, it can prevent the ion of the plating plate from sticking to the stiffeners  25 ,  65 . Moreover, because the oxidized film has high corrosion resistance and high stiffness, it has limited damages in the subsequent manufacturing process of the circuit board. 
     Especially, in the case of forming the stiffeners  25 ,  65  made of aluminum by processing the aluminum metal plate, an aluminum oxide is formed by anodizing the aluminum stiffeners  25 ,  65 . 
     Meanwhile, the plating protection layer  70  can be formed by applying an insulation material, which can prevent plating, to the stiffeners  25 ,  65 , in contrast to this embodiment. Specifically, an OSP (Organic Solderability Preservative) coating layer can be formed on the stiffeners  25 ,  65 . 
     OSP coating can be readily applied to an automatic production line because of the low cost and is environmentally friendly. 
     The manufacturing method of a circuit board in accordance with the present invention can provide forming of the stiffener together in the manufacturing of the circuit board, thereby reducing the cost and time for forming the stiffener. 
     Moreover, the manufacturing method of a circuit board in accordance with the present invention can prevent plating on the stiffener, thereby preventing a wasting of high-priced plating metal. 
     Hitherto, although a certain embodiment of the present invention have been shown and described for the above-described objects, it will be appreciated by any person of ordinary skill in the art that a large number of modifications, permutations and additions are possible within the principles and spirit of the invention, the scope of which shall be defined by the appended claims and their equivalents.