Patent Publication Number: US-2021185800-A1

Title: Circuit board

Description:
FIELD OF THE INVENTION 
     This invention relates to a circuit board, and more particularly to a circuit board having a through hole for exposing an electronic component such as fingerprint reader. 
     BACKGROUND OF THE INVENTION 
     According to product demand, a conventional circuit board may be punched to form a through hole. However, the through hole may shift or have an undesired size due to blunt punch cutter, tilted/bended circuit board or misalignment between punch cutter and circuit board. 
     As shown in  FIG. 1 , conventionally, a standard sample  10  having an inspection hole  11  is used to check the through hole. The standard sample  10  is placed on the circuit board to confirm whether the through hole on the circuit board is within the inspection hole  11  so as to determine whether the through hole conforms to standards or not. 
     Overlapping the standard sample  10  with the circuit board is necessary for checking the through hole, but personal error, such as alignment error or collimation error, may be occurred to cause false determination. Further, the use of the standard sample  10  may also reduce production efficiency. 
     SUMMARY 
     One object of the present invention is to provide two measurement marks on both sides of a through hole, respectively, to help an electronic detection device to measure the through hole for preventing false determination and increasing production efficiency. 
     A circuit board of the present invention includes a substrate having a through hole, a circuit layer, a first measurement mark and a second measurement mark. The through hole penetrates through the substrate and is provided for exposing an electronic component. The circuit layer is disposed on a surface of the substrate. The first measurement mark includes a first measurement position which is located outside a first edge of the through hole, and a shortest distance between the first measurement position and the first edge along a first direction is defined as a first distance. The second measurement mark includes a second measurement position which is located outside a second edge of the through hole, and a shortest distance between the second measurement position and the second edge along a second direction is defined as a second distance. The second direction is intersected with the first direction. 
     According to the first and second measurement marks located outside the first and second edges of the through hole, an electronic detection device can measure the first distance between the first measurement position and the first edge and the second distance between the second measurement position and the second edge to determine whether the through hole is shifted or has a undesired size so as to avoid false determination and increase production efficiency. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram illustrating a conventional standard sample. 
         FIG. 2  is a top view diagram illustrating a circuit board in accordance with a first embodiment of the present invention before forming a through hole. 
         FIG. 3  is a partial enlarged diagram of  FIG. 2 . 
         FIG. 4  is a top view diagram illustrating the circuit board in accordance with the first embodiment of the present invention after forming a through hole. 
         FIG. 5  is a partial enlarged diagram of  FIG. 4 . 
         FIG. 6  is a top view diagram illustrating a circuit board in accordance with a second embodiment of the present invention before forming a through hole. 
         FIG. 7  is a partial enlarged diagram of  FIG. 6 . 
         FIG. 8  is a top view diagram illustrating the circuit board in accordance with the second embodiment of the present invention after forming a through hole. 
         FIG. 9  is a partial enlarged diagram of  FIG. 8 . 
         FIG. 10  is a top view diagram illustrating a circuit board in accordance with a third embodiment of the present invention before forming a through hole. 
         FIG. 11  is a partial enlarged diagram of  FIG. 10 . 
         FIG. 12  is a top view diagram illustrating the circuit board in accordance with the third embodiment of the present invention after forming a through hole. 
         FIG. 13  is a partial enlarged diagram of  FIG. 12 . 
         FIG. 14  is a top view diagram illustrating a circuit board in accordance with a fourth embodiment of the present invention before forming a through hole. 
         FIG. 15  is a partial enlarged diagram of  FIG. 14 . 
         FIG. 16  is a top view diagram illustrating the circuit board in accordance with the fourth embodiment of the present invention after forming a through hole. 
         FIG. 17  is a partial enlarged diagram of  FIG. 16 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIGS. 2 to 5 , a circuit board  100  in accordance with a first embodiment of the present invention includes a substrate  110 , a circuit layer  120 , a first measurement mark  130  and a second measurement mark  140 , and preferably, the circuit board  100  further includes a protective insulation layer  150 . The substrate  110  is, but not limited to, made of polyimide (PI), the circuit layer  120  is located on a surface  110   a  of the substrate  110  and includes a plurality of circuit lines, the protective insulation layer  150  covers the circuit layer  120 . A through hole forming region  110   b  is defined on the surface  110   a , and a punch tool (not shown) is provided to punch the through hole forming region  110   b  to form a through hole  111  on the substrate  110 . The through hole  111  penetrates through the substrate  110  for revealing an electronic component such as fingerprint reader (not shown). 
     With reference to  FIGS. 2 and 3 , the though hole forming region  110   b  at least has a first predetermined edge  110   c  and a second predetermined edge  110   d , and in the first embodiment, the through hole forming region  110   b  is a rectangular region and further has a third predetermined edge  110   e  and a fourth predetermined edge  110   f . The third predetermined edge  110   e  is opposite to the first predetermined edge  110   c , the fourth predetermined edge  110   f  is opposite to the second predetermined edge  110   d . The first and second predetermined edges  110   c / 110   d  are adjacent and connected to each other, the second and third predetermined edges  110   d / 110   e  are adjacent and connected to each other, the third and fourth predetermined edges  110   e / 110   f  are adjacent and connected to each other, and the fourth and first predetermined edges  110   f / 110   c  are adjacent and connected to each other. 
     With reference to  FIGS. 2 and 3 , the first and second measurement marks  130 / 140  are located on the same surface (the surface  110   a ) of the substrate  110  in the first embodiment, and they may located on different surfaces of the substrate  110 , respectively, in other embodiments. 
     With reference to  FIGS. 2 and 3 , the circuit layer  120 , the first measurement mark  130  and the second measurement mark  140  may formed on the surface  110   a  of the substrate  110  by casting, lamination, sputtering or plating. 
     With reference to  FIGS. 2 and 3 , the circuit layer  120  and one or both of the first and second measurement marks  130 / 140  are made of a same material. The protective insulation layer  150  may cover one or both of the first and second measurement marks  130 / 140 , expose (not cover) one or both of the first and second measurement marks  130 / 140  or expose (not cover) both of the first and second measurement marks  130 / 140 . One or both of the first and second measurement marks  130 / 140  may be not electrically connected to the circuit layer  120 . In the first embodiment, both of the first and second measurement marks  130 / 140  are made of a metal material and not electrically connected to the circuit layer  120 . In other embodiments, however, one or both of the first and second measurement marks  130 / 140  are electrically connected to the circuit layer  120 . 
     With reference to  FIGS. 2 and 3 , the protective insulation layer  150  and one or both of the first and second measurement marks  130 / 140  may be made of an insulation material in other embodiments such that the protective insulation layer  150  and one or both of the first and second measurement marks  130 / 140  are formed at the same time. Preferably, all of the protective insulation layer  150 , the first measurement mark  130  and the second measurement mark  140  are formed simultaneously. 
     With reference to  FIGS. 2 and 3 , in the first embodiment, the first measurement mark  130  is located outside the first predetermined edge  110   c  of the through hole forming region  110   b , and the second measurement mark  140  is located outside the second predetermined edge  110   d  of the through hole forming region  110   b . The shapes of the first and second measurement marks  130 / 140  are not limited in the present invention, they can be any shape. The first measurement mark  130  includes at least one first measurement position  131  which is located at a first measurement edge  130   a  of the first measurement mark  130 , and the second measurement mark  140  includes at least one second measurement position  141  which is located at a second measurement edge  140   a  of the second measurement mark  140 . Preferably, the first measurement edge  130   a  and the first predetermined edge  110   c  are parallel, and the second measurement edge  140   a  and the second predetermined edge  110   d  are parallel. 
     With reference to  FIG. 3 , a shortest distance between the first measurement position  131  and the first predetermined edge  110   c  along a first direction X is defined as a first predetermined distance W 1 . And along a second direction Y intersected with the first direction X, a shortest distance between the second measurement position  141  and the second predetermined edge  110   d  is defined as a second predetermined distance W 2 . In the first embodiment, the first and second directions X/Y are perpendicular to one another. 
     With reference to  FIGS. 4 and 5 , the through hole forming region  110   b  is preferably punched by using the punch tool (not shown) to form the through hole  111 . The through hole  111  on the substrate  110  has a first edge  111   a  and a second edge  111   b , and in the first embodiment, the through hole  111  is a rectangular hole further having a third edge  111   c  and a fourth edge  111   d . The first and second edges  111   a / 111   b  are adjacent and connected with one another, the second and third edges  111   b / 111   c  are adjacent and connected with one another, the third and fourth edges  111   c / 111   d  are adjacent and connected with one another, and the fourth and first edges  111   d / 111   a  are adjacent and connected with one another. 
     With reference to  FIGS. 4 and 5 , the first and second measurement marks  130 / 140  are located outside the through hole  111 , particularly, the first measurement mark  130  is located outside the first edge  111   a  of the through hole  111 , and the second measurement mark  140  is located outside the second edge  111   b  of the through hole  111 . And one or both of the first and second measurement marks  130 / 140  are located between the circuit layer  120  and the through hole  111 . The first measurement edge  130   a  of the first measurement mark  130  is preferably parallel to the first edge  111   a  of the through hole  111 , and the second measurement edge  140   a  of the second measurement mark  140  is parallel to the second edge  111   b  of the through hole  111 . 
     With reference to  FIG. 5 , the relative positions of the first measurement position  131  of the first measurement mark  130 , the second measurement position  141  of the second measurement mark  140  and the through hole  111  are defined by a first axis X 1  and a second axis Y. In the first embodiment, the first axis X 1  extends along the first direction X and the second axis Y 1  extends along the second direction Y. 
     With reference to  FIG. 5 , the first axis X passes through the first measurement position  131  and extends toward the through hole  111 , the second axis Y 1  passes through the second measurement position  141  and extends toward the through hole  111 . The first and second axes X 1 /Y 1  are intersected at an intersection point O and an included angle D exists between them. The values of a first linear distance A between the intersection point O and the first measurement position  131 , a second linear distance B between the intersection point O and the second measurement position  141 , a third linear distance C between the first and second measurement positions  131 / 141  and the included angle D satisfy the formula presented as follows: 
         C   2   =A   2   +B   2 −2 AB  cos  D  
 
     With reference to  FIG. 5 , a shortest distance between the first measurement position  131  and the first edge  111   a  along the first direction X is defined as a first distance S 1 , and a shortest distance between the second measurement position  141  and the second edge  111   b  along the second direction Y is defined as a second distance S 2 . 
     With reference to  FIGS. 3 and 5 , the absolute difference between the first predetermined distance W 1  and the first distance S 1  is equal to or lower than 0.3 mm (|W 1 −S 1 |≤0.3 mm), and the absolute difference between the second predetermined distance W 2  and the second distance S 2  is also equal to or lower than 0.3 mm (|W 2 −S 2 |≤0.3 mm). 
     After forming the through hole  111  by the punch tool, an electronic detection device is provided to measure the first distance S 1  between first measurement position  131  and the first edge  111   a  and measure the second distance S 2  between the second measurement position  141  and the second edge  111   b . According to the measured values of the first and second distances S 1 /S 2 , the electronic detection device can determine whether the through hole  111  has an undesired diameter or shift. And if the through hole  111  is shifted, the electronic detection device is also provided to determine whether the shifted through hole  111  conforms to standards so as to prevent the false determination due to personal error and enhance manufacturing efficiency of the circuit board  100 . 
       FIGS. 6 to 9  and  FIGS. 10 to 13  show a second embodiment and a third embodiment of the present invention, respectively. In the second and third embodiments, the second predetermined edge  110   d  and the fourth predetermined edge  110   f  of the through hole forming region  110   b  are circle arc, different to the first embodiment. And the second edge  111   b  and the fourth edge  111   d  of the through hole  111  formed by the punch tool are arc edges, preferably, the second axis Y 1  passes through centers of the second edge  111   b  and the fourth edge  11   l  d. 
     A fourth embodiment of the present invention is represented in  FIGS. 14 to 17 . Different to the first embodiment, the first to fourth predetermined edges  110   c / 110   d / 110   e / 110   f  of the through hole forming region  110   b  are arc edges, and the through hole forming region  110   b  is circular in the fourth embodiment. After punching, the first to fourth edges  11   a / 111   b / 111   c / 111   d  of the through hole  111  are also arc edges and the through hole  111  is a circular hole. In the fourth embodiment, the first axis X 1  passes through the first measurement position  131 , the second axis Y 1  passes through the second measurement position  141 , and the first axis X 1  is not perpendicular to the second axis Y 1 . 
     While this invention has been particularly illustrated and described in detail with respect to the preferred embodiments thereof, it will be clearly understood by those skilled in the art that is not limited to the specific features shown and described and various modified and changed in form and details may be made without departing from the scope of the claims.