Patent Publication Number: US-2009233466-A1

Title: Surface-mounted circuit board module and process for fabricating the same

Description:
FIELD OF THE INVENTION 
     The present invention relates to a circuit board module and the process for fabricating the same, and more particularly to a surface-mounted circuit board module and the process for fabricating the same. 
     BACKGROUND OF THE INVENTION 
     With the progress of technology, the operation efficiency of the electronic apparatus is raised up. For increasing the operating power and conforming to the trend toward product size minimization, the volume of the electronic apparatus must be reduced and the design of the inner structure is more compacted. In other words, plural circuit board modules have to be disposed on a system circuit board of the electronic apparatus. A connector, for example, a conductive pin, is applied to the circuit board module for the circuit board thereof to be disposed on the system circuit board. The electronic components of the circuit board module can be electrically connected to the system circuit board through the connector. 
     With reduction of the electronic apparatus volume, the size of the connector has to be correspondingly reduced. Under the prerequisite of not affecting the power density, plural connectors have to be disposed on the circuit board module. The existing circuit board module is disposed on the system circuit board by the connectors thereof inserting into the predetermined through holes of the system circuit board. The circuit board module is further fixed on the system circuit board by soldering the joint of the connector and the through hole. However, each of the connectors has to be precisely aligned with the corresponding through holes of the system circuit board for firmly disposing the circuit board module on the system circuit board. Therefore, the insertion process is complex and time-consuming. Moreover, once the connectors and the through holes are not accurately aligned, the connectors may be damaged during the insertion step. Accordingly, the driving of the circuit board module and the system circuit board are impacted, and the yield of the electronic apparatus is lowered as well. 
     Therefore, it is required to develop a surface-mounted circuit board module and the process for fabricating the same to overcome the foregoing defects. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a surface-mounted circuit board module and the process for fabricating the same, so as to avoid the inconvenience of disposing the circuit board module on the system circuit board through inserting manner. The circuit board of the surface-mounted circuit board module comprises connectors. After the connectors are disposed on the circuit board of the surface-mounted circuit board module, the ends of each of the connectors applied to contact with the system circuit board are bent to form the second end portions. Hence the surface-mounted circuit board module can be disposed on the system circuit board by the second end portions of the connectors surface mounting on the system circuit board, and the electronic components on the circuit board of the surface-mounted circuit board module can be electrically connected to the system circuit board via the connectors. Besides, the system circuit board and the second end portion of each of the connectors comprise an included angle therebetween. The included angle is beneficial for the melted solder to exhaust and distribute evenly, so as to prevent the pinhole formation and increase the contact area between the second end portion of the connector and the system circuit board for securely surface mounting the surface-mounted circuit board module on the system circuit board. 
     According to an aspect of the present invention, a surface-mounted circuit board module disposed on a system circuit board is provided. The surface-mounted circuit board module comprises: a circuit board having at least an electronic component disposed thereon and a plurality of connectors. Each of the connectors comprises a first end portion at least partially embedded in the circuit board, a connecting portion connected with the first end portion, and a second end portion extended and bent from the connecting portion, the second end portion being surface mounted on the system circuit board for the electronic component on the circuit board to be electrically connected to the system circuit board via the connector. 
     In an embodiment, the circuit board comprises a first side and a second side corresponding to each other, and a plurality of through holes penetrating through the first and second sides of the circuit board for the first end portion of the connector to insert therein. 
     In an embodiment, the plural connectors are disposed on the first side and the second side of the circuit board, each of the plural connectors further comprises a bent structure formed by the first end portion and the connecting portion, so as to substantially vertically dispose the circuit board on the system circuit board. 
     In an embodiment, the circuit board further comprises a plurality of pads. 
     In an embodiment, the plural connectors are disposed on the first side or the second side of the circuit board, the connecting portion of the connector is substantially parallel to the first end portion, so as to substantially parallelly dispose the circuit board on the system circuit board. 
     In an embodiment, the second end portion of the connector and the system circuit board comprise an included angle therebetween, the range of the included angle is substantially from 0 to 8 degrees. 
     In an embodiment, the surface-mounted circuit board module further comprises a pick and place component disposed on the circuit board, wherein the pick and place component is a heat sink or a pick and place cap. 
     In an embodiment, the first end portion, the connecting portion, and the second end portion of each of the plural connectors are integrally formed. 
     In an embodiment, the circuit board and the system circuit board further comprise a gap therebetween. 
     According to another aspect of the present invention, there is provided a process for fabricating a surface-mounted circuit board module. The process comprises steps of: (a) providing a circuit board, the circuit board comprising at least an electronic component and a plurality of through holes; (b) providing a plurality of connectors, each of which having a first end portion and a connecting portion connected with the first end portion; (c) inserting the first end portion of the connector into the through hole of the circuit board; (d) bending the end of the connecting portion opposite to that connected with the first end portion to form a second end portion, so as to surface mount the circuit board of the surface-mounted circuit board module on a system circuit board via the second end portion of the connector. 
     In an embodiment, the step (b) includes sub-step of: (b1) bending the connector to form a bent structure by the first end portion and the connecting portion. 
     In an embodiment, a bent angle is formed between the connecting portion and the second end portion of the connector, the range of the bent angle is substantially from 90 to 98 degrees. 
     The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a flow chart for fabricating the surface-mounted circuit board module according to the first preferred embodiment of the present invention; 
         FIG. 2A  is a schematic diagram showing the surface-mounted circuit board module during assembling according to the first preferred embodiment of the present invention; 
         FIG. 2B  is a schematic diagram showing the finished surface-mounted circuit board module of  FIG. 2A  being assembling to the system circuit board; 
         FIG. 2C  is the a-a′ cross-section view of  FIG. 2B  after assembly; 
         FIG. 3  is a schematic diagram showing the surface-mounted circuit board module disposed on the system board according to the second preferred embodiment of the present invention; 
         FIG. 4  is a schematic diagram showing the surface-mounted circuit board module disposed on the system board according to the third preferred embodiment of the present invention; 
         FIG. 5  is a flow chart for fabricating the surface-mounted circuit board module according to the fourth preferred embodiment of the present invention; 
         FIG. 6A  is a schematic diagram showing the surface-mounted circuit board module of the fourth preferred embodiment of the present invention being assembling to the system circuit board; and 
         FIG. 6B  is a b-b′ cross-section view of  FIG. 6A  after assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only; it is not intended to be exhaustive or to be limited to the precise form disclosed. 
     The surface-mounted circuit board module of the present invention is disposed on a system circuit board of an electronic apparatus (figure not shown) by surface mount technology (SMT). The surface-mounted circuit board module of the present invention can be a power module or any other similar module, but not limited thereto. 
     Please refer to  FIG. 1  and  FIG. 2A , which are respectively the flow chart for fabricating the surface-mounted circuit board module and the schematic diagram showing the surface-mounted circuit board module during assembling according to the first preferred embodiment of the present invention. For fabricating the surface-mounted circuit board module  1 , a circuit board  10  is provided (step S 11 ). The circuit board  10  has a first side  101  and a second side  102 , wherein the first side  101  and the second side  102  are corresponding to each other. The circuit board  10  further comprises plural through holes  103 , which substantially vertically penetrate through the first side  101  and the second side  102  of the circuit board  10  (as shown in  FIG. 2C ). The shape of the through hole  103  is preferred to be circular, but not limited thereto. The distance from the through hole  103  to the nearest edge  104  adjacent thereto is L 1 . Conductive layers (not shown) for connecting to the trace (not shown) of the circuit board  10  can be coated at the inner sidewall of each of the through holes  103 . 
     The circuit board  10  further comprises at least an electronic component  11  and a pick and place component  12  disposed thereon. In this embodiment, the circuit board  10  comprises plural electronic components  11 . The electronic components  11  can be the components such as inductance, capacitance, and etc., which can be disposed on the first side  101  and/or the second side  102  of the circuit board  10 . The pick and place component  12  has a flat surface  121  across the first side  101  and the second side  102  of the circuit board  10 . In this embodiment, the pick and place component  12  can be a heat sink, such as an aluminum extrusion heat sink, that fixed on the circuit board  10  through adherent media like thermal adhesive etc. 
     Plural connectors  13  are also provided to fabricate the surface-mounted circuit board module  1  (step S 12 ), wherein the connectors  13  can be derived from the carrier tape (not shown). Each of the connectors  13  comprises a first end portion  131  and a connecting portion  132 , wherein the connecting portion  132  is connected to and extended from the first end portion  131 . In this embodiment, connectors  13  are composed of uniform rod-like conductive material, such as copper, aluminum, and etc. The shape of the cross-section of the connector  13  is preferred to be rectangular, wherein the length of the diagonal of the rectangular cross-section is approximately equal to the diameter of the through hole  103  of the circuit board  10  (as shown in  FIG. 2B ), but not limited thereto as well. Subsequently, the connectors  13  are bent by a jig (not shown), so as to form a bent structure  134  by the first end portion  131  and the connecting portion  132  (step S 121 ). In this embodiment, the first end portion  131  of the connector  13  is perpendicular to the connecting portion  132 . In other words, the first end portion  131  and the connecting portion  132  form a 90 degree bent structure  134 , and the connector  13  at this time is substantially an L-shape (as shown in  FIG. 2A ). 
     Next, each of the connectors  13  is corresponded to one of through holes  103 , and parts of connectors  13  are connected to the circuit board  10  by the first end portions  131  thereof inserted into the through holes  103  from the first side  101  of the circuit board  10 . The other parts of the connectors  13  are connected to the circuit board  10  by the first end portions  131  thereof inserted into the through holes  103  from the second side  102  of the circuit board  10  (step S 13 ). Therefore, the connectors  13  can be disposed on the first side  101  and the second side  102  of the circuit board  10 . In other words, the connectors  13  are not symmetrically disposed on the first side  101  and the second side  102  of the circuit board  10 . Beside, since the diagonal length of the cross-section of the connector  13  is substantially equal to the diameter of the through hole  103  of the circuit board  10 , the first end portion  131  of the connector  13  can be firmly engaged with the through hole  103 . 
     In this embodiment, each of the first end portions  131  of the connectors  13  is partially inserted into each of the through holes  103 . That is to say, only a part of the first end portion  131  of each of the connectors  13  is embedded in the circuit board  10 , whereas the rest of the first end portion  131  is exposed outside of the circuit board  10 . The length of the exposed first end portion  131  is substantially equal to half of the height of the tallest electronic component  11  disposed on the side of the circuit board  10  where the connector  13  being disposed, so as to adjust gravity center of the circuit board  10  according to the disposition of the electronic components  11 . For example: when an electronic component  11  with larger volume is disposed on the first side  101  of the circuit board  10 , a longer first end portion  131  of the connector  13  can be reserved in step S 121 . Thus when the connector  13  is inserted into the through hole  103  in step S 13  from the first side  101  of the circuit board  10 , a relative longer first end portion  131  is exposed outside of the circuit board  10  for adjusting the gravity center of the circuit board  10 , so as to avoid the collapse of the circuit board  10  when the circuit board  10  is disposed on the system circuit board  2 . Of course, in some embodiment, if the gravity center adjustment of the circuit board  10  is not taken into consideration, the length of the first end portion  131  can be reduced, and the whole first end portion  131  of each of the connectors  13  can be inserted into the through hole  103  for the connecting portion  132  to be extended directly from the circuit board  10 . 
     In addition, step S 13  of the present invention can be processed by an automatic pin insertion machine (not shown). Of course, in some embodiment, a soldering process can be performed at the through hole  103  after step S 13  to ensure the connection between the connector  13  and the circuit board  10 . Since the circular through hole  103  and the first end portion  131  of the connector  13  with rectangular cross-section have space formed therebetween, the melted solder can exhaust through the space to minimize the formation of pinhole during the soldering period. Hence the current resistance and impact on the electric conductive effect caused by the pinhole can be avoided. As regards the circuit board module after the completion of step S 13  can be disposed on a system circuit board having through holes by the connecting portions directly inserted into the through holes. 
     Please refer to  FIG. 1 ,  FIG. 2B  and  FIG. 2C , wherein  FIG. 2B  is the finished surface-mounted circuit board module of  FIG. 2A  being assembling to the system circuit board and  FIG. 2C  is the a-a′ cross-section view of  FIG. 2B  after assembly. As shown in these figures, after step S 13  is finished, an adjustment procedure for bending the connectors  13  is performed by jig (not shown). In other words, plural connectors  13  coupled to the circuit board  10  are bent. A length L 2  of the connecting portion  132  is reserved, and the end of the connecting portion  132  opposite to that connected with the first end portion  131  is bent toward the direction away from the circuit board  10 , so as to form the second end portion  133  (step S 14 ). That is to say, the second end portion  133  of the connector  13  is extended and bent from the connecting portion  132  (as shown in  FIG. 2B ). In this embodiment, each of the connectors  13  is integrally formed, wherein the first end portion  131 , the connecting portion  132 , and the second end portion  133  thereof are formed by bending. Since the second end portions  133  of the connectors  13  disposed on the first side  101  of the circuit board  10  are simultaneously bent by the jig (not shown), the second end portions  133  can be flatly formed on the same plane. Of course, the second end portions  133  of the connectors  13  disposed on the second side  102  of the circuit board  10  are also simultaneously bent, and thus the coplanar second end portions  133  can be flatly formed. After the adjustment procedure of step S 14  is finished, the surface-mounted circuit board module  1  as shown in  FIG. 2B  can be obtained. 
     Please refer to  FIG. 2B  and  FIG. 2C  again. In this embodiment, a bent angle d 1  is formed between the second end portion  133  and the connecting portion  132  on every connector  13  of the surface-mounted circuit board module  1 . The degree of the bent angle d 1  is substantially 90 to 98 degrees, preferably 93 to 95 degrees, but not limited thereto. Moreover, the length L 2  of the connecting portion  132  is larger than the distance L 1  from the through hole  103  to the edge  104 . Thus, when each of the connectors  13  is disposed on the circuit board  10 , part of the connecting portion  132  and the second end portion  133  are protruded relative to the edge  104  of the circuit board  10  (as shown in  FIG. 2C ), so the surface-mounted circuit board module  1  can contact to the system circuit board  2  via the second end portion  133  of each of the connectors  13 . 
     While disposing the surface-mounted circuit board module  1  on the system circuit board  2  of an electronic apparatus (not shown), a pick and place machine (not shown) can be used to draw the flat surface  121  of the pick and place component  12  to place the surface-mounted circuit board module  1  on the predetermined position of the system circuit board  2 . The second end portion  133  of each of the connectors  13  therefore contacts with the conductive areas  20  of the system circuit board  2 , wherein the conductive areas  20  are coated with solder. The circuit board  10  is substantially perpendicular to the system circuit board  2  at this time. Since the first end portion  131  of the connector  13  is inserted into the through hole  103  perpendicular to the circuit board  10 , the first end portion  131  is approximately perpendicular to the connecting portion  132 , and the connecting portion  132  and the second end portion  133  have a bent angle d 1  ranging from 90-98 degrees therebetween, an included angle d 2  is formed between the second end portion  133  of the connector  13  and the system circuit board  2  when the circuit board  10  is disposed on the system circuit board  2  (as shown in  FIG. 2C ). The included angle d 2  substantially ranges from 0 to 8 degrees, preferably 3 to 5 degrees, but not limited thereto. While the surface-mounted circuit board module  1  and the system circuit board  2  and reflowed in the reflow oven, the melted solder on the conductive area  20  can fill the space between the second end portion  133  of the connector  13  and the system circuit board  2  by capillary phenomenon. Therefore, the solder can be uniformly distributed, so as to increase the contact area between the second end portion  133  and the system circuit board  2  and enhance the structural strength therebetween. In addition, the included angle d 2  is advantageous for the melted solder to exhaust, so as to avoid the formation of holes, such as pinholes, and prevent the impact on conductive effect caused by the hole formation. Moreover, the gravity center of the circuit board  10  can be adjusted by the disposition of the pick and place component  12  and the modulation of the length of the first end portion  131  of the connector  13  exposed relative to the circuit board  10 . Thus even the circuit board  10  of the surface-mounted circuit board module  1  with plural electronic components  11  is vertically disposed on the system circuit board  2 , the collapse of the surface-mounted circuit board module  1  due to the off balance can be prevented by the design of the present invention. In such way, the surface-mounted circuit board module  1  can be firmly disposed on the system circuit board  2  via the second end portions  133  of the connectors  13  surface mounted on the system circuit board  2 , and the electronic components  11  on the circuit board  10  can be electrically connected to the system circuit board  2  through the connectors  13 . Nevertheless, to clearly illustrate the included angle d 2  between the second end portion  133  of the connector  13  and the system circuit board  2 , solder that filled the space between the system circuit board  2  and the second end portion  133  of the connector  13  on the left of  FIG. 2C  is not shown. 
     Please refer to  FIG. 2B  and  FIG. 2C  again, since the length L 2  of the connecting portion  132  is larger than the distance L 1  from the through hole  103  to the edge  104  of the circuit board  10 , a gap  14  can be created between the edge  104  of the circuit board  10  and the system circuit board  2 . When the electronic apparatus (not shown) is bumped or shocked, the gap  14  can not only provide cushion effect to avoid the loosening of the surface-mounted circuit board module  1  from the system circuit board  2  that may affect the efficiency of the electronic apparatus but also keep space for the layout of the system circuit board  2 . 
     Please refer to  FIG. 3 , which is a schematic diagram showing the surface-mounted circuit board module disposed on the system circuit board according to the second preferred embodiment of the present invention. The surface-mounted circuit board module  1  is perpendicularly disposed on the system circuit board  2 . The circuit board  10  has electronic components  11 , pick and place component  15  and plural connectors  16  disposed thereon, wherein the disposition of the electronic components  11  is the same as that shown in  FIG. 2B . The pick and place component  15  in this embodiment is preferred to be a pick and place cap that has a flat surface  151  across the first side  101  and the second side  102  of the circuit board  10 , so as to draw the flat surface  151  to place the surface-mounted circuit board module  1  on the predetermined position of the system circuit board  2  by the automatic pick and place machine (not shown). The pick and place component  15  can be removed from the circuit board  10  after the surface-mounted circuit board module  1  is disposed on the system circuit board  2 . In other words, the pick and place component  15  can be a disposable pick and place cap, but not limited thereto. 
     In addition, the connectors  16  are processed according to the flow chart shown in  FIG. 1 . Each of the connector  16  is bent in step S 121  to form the bent structure  164  by the first end portion  161  and the connecting portion  162 . However, the second end portion  163  on every connector  16  is bent toward the circuit board  10  in step S 14  to make the connectors  16  as square bracket shape. The relationships among the first end portion  161 , the connecting portion  162 , and the second end portion  163  of the connector  16  and the relationships among the connector  16 , the circuit board  10  and the system circuit board  2  are similar to that shown in  FIG. 2B  and  FIG. 2C , and thus it is not redundantly described. 
     According to the foregoing descriptions and incorporated with  FIG. 2C  and  FIG. 3 , it is to be understood that the angles between the first end portion and the connecting portion and between the connecting portion and the second end portion of the connector are not limited, and the methods to form the bent structure and the bent angle of the connector are not limited as well. The first end portion, the connecting portion, and the second end portion of the connector can be bent as a Z-shape (as shown in  FIG. 2C ) or a square bracket shape (as shown in  FIG. 3 ) depending on user&#39;s requirements. In other words, the method of bending the connectors to form the first end portions and the connecting portions first, and then forming the second end portions by bending the connectors after the connectors being disposed on the circuit board for each of the second end portions to form an included angle of 0-8 degrees with the system circuit board while the surface-mounted circuit board module being surface mounted on the system circuit board belongs to the concept of the present invention. 
     Please refer to  FIG. 4 , which is a schematic diagram showing the surface-mounted circuit board module disposed on the system board according to the third preferred embodiment of the present invention. The structure of the surface-mounted circuit board module  1  is similar to that of the first preferred embodiment shown in  FIG. 2B . However, in this embodiment, the circuit board  10  of the surface-mounted circuit board module  1  further comprises plural pads  105  electrically conducted to the trace (not shown) of the circuit board  10 . The pads  105  are disposed on the first side  101  and/or the second side  102  near the edge  104  of the circuit board  10 . The length L 2  of the connecting portion  132  of the connector  13  is substantially equal to the distance L 1  from the through hole  103  to the edge  104  of the circuit board  10 . Thus the second end portion  133  of each of the connectors  13  is approximately coplanar with the edge  104  of the circuit board  10 . 
     When the surface-mounted circuit board module  1  is disposed on the system circuit board  2 , the edge  104  of the circuit board  10  leans against the surface of the system circuit board  2  for the pads  105  on the circuit board  10  and the second end portion  133  of the connector  13  to contact with the conductive area  20  on the system circuit board  2 . Since solder is coated on the conductive area  20 , the circuit board  10  of the surface-mounted circuit board module  1  can be surface mounted on the system circuit board  2  via the pads  105  and the connectors  13  after reflow procedure, so as to electrically connect the electronic components  11  and the system circuit board  2 . In this embodiment, the electronic components  11  can be electrically connected to the system circuit board  2  via the pads  105 , and thus the connectors  13  can be replaced by non-conductive material to serve as supporting structures to prevent the surface-mounted circuit board module  1  from collapsing while the electronic apparatus is bumped or shocked. 
     Of course, the present invention is not limited to the foregoing embodiments.  FIG. 5  is a flow chart for fabricating the surface-mounted circuit board module according to the fourth preferred embodiment of the present invention, and  FIG. 6A  and  FIG. 6B  are schematic diagrams respectively showing the surface-mounted circuit board module being assembling to the system circuit board and the b-b′ cross-section view of  FIG. 6A  after assembly. Please refer to  FIG. 5 ,  FIG. 6A  and  FIG. 6B , a circuit board  30  is provided to fabricate the surface-mounted circuit board module  3  (step S 11 ). The circuit board  30  has a first side  301  and a second side  302  corresponding to each other. The circuit board  30  further comprises plural through holes  303  substantially vertically penetrate through the first side  301  and second side  302  (as shown in  FIG. 6B ). The shape of the through hole  303  is preferred to be circular, but not limited thereto. In addition, electronic components  31  are disposed on the first side  301  and second side  302  of the circuit board  30 , wherein the electric components  31  can be inductance, capacitance, and etc., but not limited thereto. 
     Subsequently, plural connectors  32  are provided. Each of the connectors  32  has a first end portion  321  and a connecting portion  322  connected with the first end portion  321  (step S 12 ). In this embodiment, the connectors  32  are composed of uniform rod-like conductive material. The cross-section of each of the connectors  32  is preferred to be rectangular, wherein the length of the diagonal of the cross-section is approximately equal to the diameter of the through hole  303  of the circuit board  30 . As regards the connecting portion  322  is parallel to the first end portion  321 . In other words, the connecting portion  322  is extended from the first end portion  321  and coplanar with the first end portion  321  to form the connecting portion  322  and the first end portion  321  as a straight linear shape (as shown in  FIG. 6B ). Besides, the connectors  32  can be derived from the metal continuous reel (not shown). 
     Next, the first end portion  321  of each of the connectors  32  is inserted into the though hole  303  of the circuit board  30  (step S 13 ). In this embodiment, the first end portion  321  of each of the connectors  32  is inserted into the through hole  303  from the first side  301  of the circuit board  30 , and thus the connectors  32  are extended only from one side. Since the length of the diagonal of the rectangular cross-section of the connector  32  is substantially the same as the diameter of the through hole  303  of the circuit board  30 , the connectors  32  can be firmly fixed in the through holes  303  of the circuit board  30 . 
     After all the connectors  32  are inserted in the through holes  303  via the first end portions  321 , the connectors  32  are processed by a jig (not shown) to bend the end of the connecting portion  322  opposite to that connected to the first end portion  321  to form a second end portion  323  (step S 14 ). In other words, the second end portion  323  is extended and bent from the connecting portion  322  of the connector  32 . In this embodiment, the length of the connecting portion  322  of the connector  32  is L 2 , which is larger than the height L 1  of the tallest electronic component  31  on the first side  301  of the circuit board  30 . The connecting portion  322  and the second end portion  323  comprise a bent angle d 1  therebetween (as shown in  FIG. 6B ). The bent angle d 1  substantially ranges from 90 to 98 degrees, preferably 93 to 95 degrees, but not limited thereto. After the second end portion  323  is processed, the surface-mounted circuit board module  3  shown in  FIG. 6A  can be obtained. Since the second end portions  323  are bent (step S 14 ) after the linear connectors  32  are inserted into the though holes  303  of the circuit board  30  (step S 13 ), the flatness of the second end portions  323  of the connectors  32  can be ensured. 
     Similarly, the surface-mounted circuit board module  3  can be placed on the system circuit board  2  with the first side  301  of the circuit board  30  facing the system circuit board  2  by an automatic pick and place machine (not shown). Since the connectors  32  are disposed on and extended from the first side  301  of the circuit board  30 , the surface-mounted circuit board module  3  can be disposed on the system circuit board  2  through the second end portions  323  of the connectors  32  contacting with the conductive areas  20  of the system circuit board  2 . Under this circumstance, the circuit board  30  of the surface-mounted circuit board module  3  is parallel to the system circuit board  2 . In comparison with the surface-mounted circuit board module  1  shown in  FIG. 2B , the electronic component  31  on the second side  302  of the circuit board  30  is applied as the pick and place component in this embodiment. That is to say, the automatic pick and place machine (not shown) draws the larger flat surface of the electronic component  31  on the second side  302  of the circuit board  30 , so as to pick and place the surface-mounted circuit board module  3 . 
     Since the first end portion  321  of the connector  32  is vertically embedded in the circuit board  30 , the connecting portion  322  is parallel to the first end portion  321 , and the second end portion  323  and the connecting portion  322  have the bent angle d 1  therebetween, an included angle d 2  will be created between the second end portion  323  and the system circuit board  2  while the surface-mounted circuit board module  3  is disposed on the system circuit board  2 . The included angle d 2  ranges from 0 to 8 degrees, preferably 3 to 5 degrees, but not limited thereto. In addition, the conductive area  20  in contact with the second end portion  323  can be coated with solder. Therefore, the space between the second end portion  323  of the connector  32  and the system circuit board  2  can be filled with melted solder owing to the capillary phenomenon during soldering process. The included angle d 2  between the second end portion  323  and the system circuit board  2  is not only advantageous for increasing the contact area between the second end portion  323  and the system circuit board  2  but also advantageous for exhausting. Thus the increase of current resistance and impact on conductive efficiency caused by the pinhole formation can be prevented. Accordingly, the surface-mounted circuit board module  3  can be firmly surface mounted on the system circuit board  2  via the second end portions  323  of every connector  32 , and the electronic components  31  on the circuit board  30  can be electrically connected to the system circuit board  2  through the connectors  32 . 
     Please refer to  FIG. 6B  again. Because the length L 2  of the connecting portion  322  of the connector  32  is larger than the height L 1  of the tallest electronic component  31  on the first side  301  of the circuit board  30 , a gap  33  can be created between the circuit board  30  and the system circuit board  2 . The gap  33  is beneficial to cushion the impact and lower the layout limitation of the system circuit board  2 . Please be advised that for clearly illustrating the included angle d 2  between the second end portion  323  and the system circuit board  2 , the solder filled between the system circuit board  2  and the second end portion  323  of the connector  32  on the left of  FIG. 6B  is not shown. 
     Of course, in some embodiments, the first end portions  321  of the connectors  32  can be inserted into the through holes  303  of the circuit board  30  from the second side  302 . The connectors  32  therefore are disposed on and extended from the second side  302 . Under this circumstance, the circuit board  30  of the surface-mounted circuit board module  3  can be parallelly disposed on the system circuit board  2  with the second side  302  thereof facing the system circuit board  2 . 
     According to the foregoing descriptions, it is to be understood that the manner the surface-mounted circuit board module disposed on the system circuit board can be adjusted by slightly modifying the process for fabricating the surface-mounted circuit board module. For example, when fabricating the surface-mounted circuit board module  1 , each of the connectors  13  is bent to form the bent structure  134  by the first end portion  131  and the connecting portion  132  first. Then the first end portions  131  of the connectors  13  are inserted into the through holes  103  from the first side  101  and the second side  102  of the circuit board  10 . The connectors  13  are subsequently bent to form the second end portions  133 , so as to dispose the circuit board  10  of the surface-mounted circuit board module  1  on the system circuit board  2  perpendicularly (as shown in  FIG. 2C ,  FIG. 3 , and  FIG. 4 ). If the first end portion  321  and the connecting portion  322  of every connector  32  are parallel and coplanar, the connectors  32  are inserted into the through holes  303  from the first side  301  or the second side  302  of the circuit board  30 , and then the connectors  32  are bent to form the second end portions  323 , the circuit board  30  of the surface-mounted circuit board module  3  can be parallelly disposed on the system circuit board  2  via the connectors  32  (as shown in  FIG. 6B ). Hence the surface-mounted circuit board module can be flexibly disposed on the system circuit board depends on the layout of the system circuit board. 
     When the circuit board of the surface-mounted circuit board module is desired to be perpendicularly disposed on the system circuit board (as shown in  FIG. 2C ,  FIG. 3 , and  FIG. 4 ), the length of the first end portion of the connector can be adjusted in step S 121 , and the first end portion of each connectors can be partially inserted into the through holes of the circuit board in step S 13 . Thus the gravity center of the circuit board can be adjusted by the exposed first end portion of each of the connectors to avoid the collapse of the circuit board. 
     Besides, in the present invention, an included angle d 2  with the range of 0 to 8 degrees is formed between the second end portion of the connector of the surface-mounted circuit board module and the system circuit board (as shown in  FIG. 2C  and  FIG. 6B ). Hence the solder can exhaust and fill the space between the second end portion and the system circuit board evenly and entirely, so as to reduce the pinhole formation and increase the contact area between the second end portion and the system circuit board. 
     In some embodiments, the length of the connecting portion of the connector of the surface-mounted circuit board module can be adjusted in steps S 12  or S 121 , so as to form a cushion gap between the circuit board and the system circuit board while the surface-mounted circuit board module is disposed on the system circuit board (as shown in  FIG. 2C ,  FIG. 3 , and  FIG. 6B ). Moreover, since the circuit board of the surface-mounted circuit board module is elevated disposed on the system circuit board, the space on the system circuit board is not occupied by the surface-mounted circuit board module. Thus the layout of the system circuit board will not be limited with the disposition of the surface-mounted circuit board module. 
     In some embodiments of the present invention, the gravity center of the circuit board of the surface-mounted circuit board module can be adjusted by disposing a pick and place component (as shown in  FIG. 2B ,  FIG. 3 , and  FIG. 4 ). Furthermore, if the pick and place component is a heat sink, it is not necessary to remove the heat sink after the surface-mounted circuit board module is disposed on the system circuit board. The heat dissipating effect of the surface-mounted circuit board module can be further raised by keeping the heat sink on the circuit board. 
     To sum up, the surface-mounted circuit board module is surface mounted on the system circuit board by the second end portions of the connectors. Therefore, the inconvenience for inserting the connectors into the through holes of the system circuit board can be prevented. In addition, the surface-mounted circuit board module can be vertically or horizontally disposed on the system circuit board by modifying the shape of the connectors and the manner that the connectors being inserted into the circuit board. So the disposition of the surface-mounted circuit board module is more flexible. Moreover, since the second end portions of the connectors are bent after the connectors are coupled to the circuit board and after the circuit board is tested, the flatness of the second end portions can be ensured and the impact to the flatness of the second end portions caused by the test can be reduced. 
     Furthermore, the soldering area between the second end portion of the connector and the system circuit board can be increased and gas in the melted solder can be exhausted through the included angle d 2 , so as to fortify the structural strength between the surface-mounted circuit board module and the system circuit board and prevent the formation of the pinhole. The cushion gap between the circuit board and the system circuit board can be created by adjusting the length of the connecting portion of the connector. Whereas the gravity center of the circuit board can be revised by modifying the length of the first end portion of the connector or disposing the pick and place component. All the foregoing features are advantageous for the surface-mounted circuit board module to be firmly and securely surface mounted on the system circuit board. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.