Abstract:
A method of manufacturing an electronic package module is provided. The method forms dual-side and selective encapsulation by using a dam filling process and a sacrificial layer. Electronic components are protected from electromagnetic interference while not interfering functioning of specific electronic components which are not encapsulated.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to a method of manufacturing an electronic package module; in particular, to a method of forming selective encapsulation by using a dam and filling process. Another aspect of the present disclosure relates to an electronic package module manufactured by the same. 
     2. Description of Related Art 
     A conventional electronic package module includes a circuit board and a plurality of electronic components mounted on the circuit board. The electronic components are for example chip packages, passive components, etc. Additionally, most electronic package modules include molding compounds for encapsulating the electronic components. 
     However, encapsulation interferes with the operation of and is therefore not appropriate for some electronic components such as optical components (e.g. CMOS image sensors (CIS), charge-coupled devices (CCD), light emitting diodes (LED), etc.) and connectors. 
     SUMMARY OF THE INVENTION 
     The object of the present disclosure is to provide a method of manufacturing an electronic package module for forming dual-side encapsulation by using a dam and filling process and a sacrificial layer. 
     An embodiment of the present disclosure comprises the steps: providing a circuit board having a first mounting face and a second mounting face, wherein the first mounting face includes a first encapsulation region and a first predetermined region, and the second mounting face has a second encapsulation region and a second predetermined region; mounting at least one first-type electronic component onto the first mounting face at the first encapsulation region; forming a first dam structure at the border between the first encapsulation region and the first predetermined region; forming a first encapsulation at the first encapsulation region; forming a second dam structure at the border between the second encapsulation region and the second predetermined region; forming a second encapsulation at the second encapsulation region; forming a first metal shield layer on the first encapsulation region and contacting at least one contact pad on the circuit board; forming a first sacrificial layer on the first metal shield layer; forming a second metal shield layer on the second encapsulation region and contacting the circuit board; and removing the first sacrificial layer. 
     By using a dam and filling process to form molding compound and metal coating at regions to be encapsulated, the abovementioned method of manufacturing an electronic package module according to the present disclosure can selectively encapsulate without affecting operation of particular components and further provide metal shield protecting against electromagnetic interference. 
     Additionally, the present disclosure provides an electronic package module including a circuit board, a first encapsulation, a second encapsulation, a first dam structure, a second dam structure, a first metal shield layer, and a second metal shield layer. The first dam structure and the second dam structure are made of photo-curable metal glue. The circuit board includes a first mounting face and a second mounting face. The first mounting face has at least one encapsulation region and at least one predetermined region. The second mounting face has at least one second encapsulation region and at least one second predetermined region. The first encapsulation is disposed above the first encapsulation region and covers at least one electronic component. The second encapsulation is disposed above the second encapsulation region and covers at least one electronic component. At least one side of the first encapsulation is adjacent to the first dam structure. At least one side of the second encapsulation is adjacent to the second dam structure. The first metal shield layer covers the upper surface of the first encapsulation and the first dam structure and is electrically connected to at least one contact pad on the circuit board. The second metal shield layer covers the upper surface of the second encapsulation and the second dam structure and is electrically connected to at least one contact pad on the circuit board. 
     In order to further the understanding regarding the present disclosure, the following embodiments are provided along with illustrations to facilitate the disclosure of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A-1L  shows a sequential process of a method of manufacturing an electronic package module according to a first embodiment of the present disclosure; 
         FIG. 2A  shows a top view of a step of a method of manufacturing a plurality of electronic package modules according to the present disclosure; and 
         FIG. 2B  shows a bottom view of a step of a method of manufacturing a plurality of electronic package modules according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following embodiments are used to describe a method of manufacturing electronic package modules according to the present disclosure. The present disclosure is not limited to the particular environment, application or special implementations described in the embodiments. Therefore, the embodiments are not meant to limit the present disclosure. 
     Additionally, the first-type electronic components refer to IC chip, chip packages, discrete components or passive components which can operate normally after being encapsulated. The second-type electronic components refer to connector units or optical components such as CMOS image sensors, CCD or LEDs, which cannot operate normally after being encapsulated. 
       FIG. 1A  to  FIG. 1L  shows schematic diagrams of processes of a method of manufacturing an electronic package module according to a first embodiment of the present disclosure. In the present embodiment, first a circuit board  11  is prepared as shown in  FIG. 1A . The circuit board  11  has a first mounting face  111  and a second mounting face  112  at different sides. The first and second mounting faces do not refer to any order regarding front and rear, upper and lower, or front and back. The first mounting face  111  includes a first encapsulation region and a first predetermined region (not labelled in the figures). The second mounting face  112  includes a second encapsulation region and a second predetermined region (not labelled in the figures). In the present embodiment, the first encapsulation region is positioned at the periphery of the first mounting face and the first predetermined region is positioned at the center of the first mounting face. The second encapsulation region and the second predetermined region are positioned at the second mounting face  112 . However, the present disclosure is not limited thereto. The quantity, shape, position and dimension of the encapsulation region or predetermined region can be designed according to the need. Additionally, the circuit board  11  has at least one contact pad  17  made of electrically conductive material for grounding. The contact pad  17  is positioned on the circuit board  11  or embedded in the circuit board  11 , and is exposed at the first mounting face  111 , the second mounting face  112 , or the side of the circuit board  11 . Next, as shown in  FIG. 1A , the first-type electronic components  181  are mounted on the circuit board  11  at the first encapsulation region. 
     Next, as shown in  FIG. 1B , a first dam  121  is formed at the boundary between the first encapsulation and the first predetermined region of the circuit board  11 . The first dam  121  can be made of photoreactive polymer, which can be cured by light as it is being coated to form a dam structure of a particular height, but is not limited thereto as long as a dam structure of a particular height can be formed at the boundary between the first encapsulation region and the first predetermined region. In the present embodiment, the first dam  121  and the contact pad  17  do not overlap. In other words, after the first dam  121  has been formed, the contact pads  17  are still exposed at the first mounting face  111 , the second mounting face  112  or the side of the circuit board  11 , for increasing the contact area between subsequently formed metal shield layers and the contact pads  17 . Then, using the first dam  121  as a barrier, a first encapsulation  131  is formed on the circuit board  11  at the first encapsulation region and covers the first-type electronic component  181 . After the first encapsulation  131  has been cured, the surface thereof is polished and the selective encapsulation of the first-type electronic component  181  is completed. At this moment, the first encapsulation  131  has at least one side wall adjacent to the first dam  121 . 
     Referring to  FIG. 1C , as mentioned above, the second mounting face  112  of the circuit  11  is likewise partitioned into an encapsulation region and a predetermined region (not labelled), such as a second encapsulation region and a second predetermined region. The second encapsulation region and the second predetermined region are respectively positioned at different sides of the circuit board  11 . As shown in  FIG. 1C , the first-type electronic components  182 ,  182 ′ are mounted on the second mounting face  112  of the circuit board  11  at the second encapsulation region. 
     Next, referring to  FIG. 1D , a second dam  122  is formed at the boundary between the second encapsulation region and the second predetermined region of the circuit board  11 . Similarly, the second dam  122  can be made of photoreactive polymer, which can be cured by light as it is being coated to form a dam structure of a particular height, but is not limited thereto as long as a dam structure of a particular height can be quickly formed at the boundary between the second encapsulation region and the second predetermined region. In the present embodiment, the second dam  122  and the contact pad  17  do not overlap, for increasing the contact area between subsequently formed metal shield layers and the contact pads  17 . Then, using the second dam  122  as a barrier, a second encapsulation  132  is formed on the circuit board  11  at the second encapsulation region and covers the first-type electronic component  182 ,  182 ′. After the second encapsulation  132  has been cured, the surface thereof is polished and the selective encapsulation of the first-type electronic component  182 ,  182 ′ is completed. At this moment, the second encapsulation  132  has at least one side wall adjacent to the second dam  122 . Of particular note, at least one surface of the first-type electronic component  182 ′ is exposed at the second encapsulation  132 . For example, as shown in  FIG. 1D , the height of the first-type electronic component  182 ′ (namely the distance between the upper surface of the first-type electronic component  182 ′ and the second mounting face  112 ) is greater than the height of the second encapsulation  132 , and the second encapsulation  132  partially covers the first-type electronic component  182 ′. 
     Next, in order to build a metal shield layer protecting against electromagnetic interference on the first encapsulation region of the circuit board  11 , a second sacrificial layer  141  is coated on the first predetermined region of the circuit board  11 . The second sacrificial layer  141  does not cover the contact pad  17  such as the ground pad, as shown in  FIG. 1E . Then, as shown in  FIG. 1F , a first metal shield layer  151  is coated on the entire surface and contacts the circuit board  11 . Of particular note, the contact pad  17  exposed at the first mounting face  111  and not covered by the second sacrificial layer  141  directly contacts the first metal shield layer  151  to achieve electrical connection. Next, as shown in  FIG. 1G , in order to carry out a dual-side encapsulation, a first sacrificial layer  142  is formed at the entire surface of the first metal shield layer  151 . 
     The method of manufacturing an electronic package module according to the present embodiment can use laser to form compartments, forming metal shield compartments for particular first-type electronic components. The following description uses the first-type electronic components  182 ,  182 ′ on the second mounting face  112  as examples, but does not limit the present disclosure thereto. 
     Referring to  FIG. 1H , after forming the second encapsulation  132  on the circuit board  11  at the second encapsulation region by using the second dam  122 , and polishing the surface of the second encapsulation  132 , a third sacrificial layer  143  is formed on the second predetermined region and the second encapsulation region of the circuit board, for protecting the surface. The third sacrificial layer  143  on the second predetermined region covers the second encapsulation  132  and the first-type electronic component  182 ′. Of particular note, the contact pad  17  exposed at the second mounting face  112  is not covered by the third sacrificial layer  143 . Therefore, a metal shield layer subsequently formed can contact the contact pad  17  and achieve electrical connection thereto. 
     Next, referring to  FIG. 1I , in order to form individual metal shield compartments for specific first-type electronic components  182 ,  182 ′, laser can be used at necessary locations to drill grooves on the second encapsulation  132 , until the contact pad  17  on the circuit board  11  is exposed. The difference in absorption of laser between the contact pad  17  and the second encapsulation  132  can be used to mark the end of the laser cutting at the circuit board  11 , but the present disclosure is not limited thereto and can use other methods, such as routing, to drill the encapsulation  132  while preserving the circuit board  11 . 
     After the groove has been drilled, metal glue  16  is filled in the groove and cured, as shown in  FIG. 1I , thereby achieving individual metal shield compartments for the first-type electronic components  182 ,  182 ′. Subsequently forming a metal shield layer can strengthen the protection against electromagnetic interference. The metal glue  16  can be a conventional metal glue, preferably a metal glue which can be cured by heat, but is not limited thereto as long as it can be filled in a narrow groove and can be completely cured. 
     Next, referring to  FIG. 1J , a portion of the third sacrificial layer  143  on the second encapsulation region is removed, such that the third sacrificial layer  143  only covers the first-type electronic component  182 ′ and the second predetermined region. 
     Referring to  FIG. 1K , a second metal shield layer  152  is coated on the entire exterior such that the second metal shield layer  152  covers the exterior of the electronic package module and contacts the circuit board  11 . For example, the second metal shield layer  152  can completely cover the lateral of the circuit board  11 , and contact the contact pads  17  on the lateral sides of the circuit board and the contact pads  17  exposed at the second mounting face  112 , achieving electrical connection thereto. Subsequently the first sacrificial layer  142 , the second sacrificial layer  141 , and the third sacrificial layer  143  are removed. As such, metal shield layers are selectively formed on the two faces of the circuit board  11  (the first mounting face  111  and the second mounting face  112 ) as shown in  FIG. 1L . 
     Lastly, a second-type electronic component  191  can be mounted on the first mounting face  111  at the first predetermined region, and a second-type electronic component  192  can be mounted on the second mounting face  112  at the second predetermined region. The second-type electronic components  191 ,  192  can be optical components, sensors or connectors. 
     In the present embodiment, the first-type electronic components  181 ,  182 ,  182  and the second-type electronic components  191 ,  192  are mounted on the circuit board  11  for example by surface mount technology (SMT). The types, location and quantities of the first-type electronic components  181 ,  182 ,  182 ′ and the second-type electronic components  191 ,  192  can be designed according to the need. Moreover, the first encapsulation  131  and the second encapsulation  132  can be formed for example by resin transfer molding or by injection molding, but is not limited thereto. Additionally, the first metal shield layer  151  and the second metal shield layer  152  can be formed by spray coating, electroless plating, sputtering, etc. Additionally, the sacrificial layers  141 ,  142 ,  143  can be ink that compose of photosensitive medium or thermoplastic resin, such as liquid photosensitive ink, but is not limited thereto. The sacrificial layers  141 ,  142 ,  143  are used to remove the contamination produced by process and to protect the surface under the sacrificial layers  141 ,  142 ,  143 . Organic solvents can be used to remove the sacrificial layers  141 ,  142 ,  143 , but is not limited thereto. 
     In an embodiment of the present disclosure, the first dam  121  and the second dam  122  can be conductive or not conductive. In the condition that the first dam  121  and the second  122  are both conductive and formed by curing a photo-curable metal glue which is composed of conductive medium, the first dam  121  and the second dam  122  directly contact the contact pads  17  on the circuit board  11 . Furthermore, the first metal shield layer  151  electrically connect to the first dam  121  and the second metal shield layer  152  electrically connect to the second dam  122 . Therefore, the first metal shield layer  151  and the second metal shield layer  152  can be electrically connected to the contact pads  17 , such as ground pads, through the first dam  121  and the second dam  122 . 
     Moreover, as shown in  FIG. 1E ,  FIG. 1F  and  FIG. 1G , regarding the protrusion of the first-type electronic component  182 ′ over the second encapsulation  132 , the present embodiment uses a carrier having an indentation whose shape and dimension fits the shape and dimension the first-type electronic component  182 ′ for accommodating the protruding portion of the first-type electronic component  182 ′. 
     In another embodiment of the present disclosure, the first mounting face  111  can have a plurality of first encapsulation regions. According to design, at least one of these first encapsulation regions can be formed with a first encapsulation  131  by using a first dam  121 . Alternately, the second mounting face  112  can have a plurality of second encapsulation regions. According to design, at least one of these second encapsulation regions can be formed with a second encapsulation  132  by using a second dam  122 . 
       FIG. 2A  shows a top view of a step of a method of manufacturing a plurality of electronic package modules according to the present disclosure.  FIG. 2B  shows a bottom view of a step of a method of manufacturing a plurality of electronic package modules according to the present disclosure. Through method of manufacturing an electronic package module mentioned in the above embodiments, a plurality of electronic package modules can be completed at the same time.  FIG. 1A  to  FIG. 1L  can represent one of the electronic package modules shown in  FIG. 2A  and  FIG. 2B .  FIG. 2A  and  FIG. 2B  are respectively a top view and a bottom view corresponding to  FIG. 1J . 
     The method of the present embodiment carries out multiple electronic package modules at the same time. In steps shown in  FIG. 1B  and  FIG. 1D , a frame F can be used as a barrier to form the first encapsulation  131  and the second encapsulation  132  at the first encapsulation region and the second encapsulation region of the circuit board  11 . The frame F is temporarily fixed at the border of the circuit board and surrounds the sides of the circuit board. 
     After completing the step shown in  FIG. 1J , a cutting machine or laser cutter is used to cut the circuit board to obtain individual modules, such that ground traces are exposed at the sides of the module boards. Namely, the cut lines C 1 , C 2  are cut. Afterward, in the steps shown in  FIG. 1K  to  FIG. 1L , the second metal shield layer  152  is coated on the entire surface of the electronic package modules to obtain a plurality of electronic package modules having complete metal shields. 
     Referring to  FIG. 1L , the second-type electronic components  191 ,  192  can be respectively mounted on the predetermined regions of the first mounting face  111  and the second mounting face  112  of the circuit board. Both faces of the circuit board are partially formed with encapsulations, and the electronic components not suitable to be encapsulated are placed at the predetermined regions. Protection against electromagnetic interference, shield compartments and not covering the second-type electronic components with encapsulations are achieved. 
     While the invention has been disclosed with respect to a limited number of embodiments, numerous modifications and variations will be appreciated by those skilled in the art. It is intended, therefore, that the following claims cover all such modifications and variations that may fall within the true spirit and scope of the invention.