Abstract:
A manufacturing method of electronic packaging includes the steps of preparing a metallic plate having an array of cover portions, soldering the metallic plate to a circuit board having encapsulated areas corresponding to the cover portions and employing a cutting process to obtain multiple electronic packages. Thus, the invention has the advantages of low cost and high efficiency

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to the fabrication of electronic packages and more particularly, to a manufacturing method of electronic packaging for fabricating electronic packages rapidly. 
         [0003]    2. Description of the Related Art 
         [0004]    Conventionally, the fabrication of electronic packages, for example, MEMS (MicroElectrical-Mechanical System) microphone packages, is to form a plurality of encapsulated areas with electronic devices on a circuit board, and then to stack metallic covers on the encapsulated areas of the circuit board individually by means of a pick-and-place machine, and then to perform reflowing and cutting processes, thereby obtaining the desired electronic packages. 
         [0005]    This conventional electronic package manufacturing method is complicated and time-consuming. Further, if the size of the electronic package is reduced, this method may be unable to accurately position the metal covers on the encapsulated areas, lowering the yield rate and increasing the manufacturing cost. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a manufacturing method of electronic packaging, which effectively shortens electronic package manufacturing time, reduces electronic package manufacturing cost and simplifies electronic package manufacturing process. 
         [0007]    To achieve this and other objects of the present invention, a manufacturing method of electronic packaging comprises the steps of: (a) preparing a metallic plate comprising a plurality of cover portions arranged in an array and a bridge portion connecting the cover portions; (b) soldering the metallic plate to a circuit board comprising a plurality of encapsulated areas corresponding to the cover portions to enable the encapsulated areas to be covered by the cover portions; and (c) cutting the metallic plate and the circuit board along the bridging portion to obtain a plurality of electronic packages. By means of directly stacking a metallic cover array-like metallic plate having an array of cover portions on a printed circuit board having multiple encapsulating areas, the invention enables multiple cover portions to be accurately positioned on a printed circuit board, effectively shortening the electronic package manufacturing time, reducing the electronic package manufacturing cost and simplifying the electronic package manufacturing process. 
         [0008]    Further, the step (b) is achieved by means of applying a solder material to at least one of the metallic plate and the circuit board and then employing a reflow soldering technique to solder the metallic plate to the circuit board. 
         [0009]    Further, the step (a) for preparing the metallic plate having a sound hole on each cover portion for the passing of sound waves comprises the sub-steps of: (a1) forming a release layer on a substrate and an array of insulative blocks on said release layer; (a2) forming a seed layer on the release layer and the insulative blocks, the seed layer comprising a plurality of protrusions corresponding to said insulative blocks for forming the cover portion and a plurality of connection portions connected with the protrusions for forming the bridge portion, and then forming a plurality of insulative blocks on the protrusions of said seed layer for forming the sound hole on each said cover portion; (a3) electroplating a metallic layer on the seed layer for forming the metallic plate; and (a4) removing the substrate, the release layer, said insulative blocks and the seed layer in proper order so to obtain the metallic plate. 
         [0010]    It is to be understood that the metallic plate can be prepared without any sound hole on the cover portion. In this case, the sound hole forming step in the sub-step (a2) is omitted. 
         [0011]    Further, in step (a), the metallic plate can be prepared having a sound hole on each cover portion, and a plurality of through holes on the bridge portion. In this case, after the formation of the seed layer on the release layer and the insulative blocks, it simply needs to form insulative blocks on the protrusions of the seed layer for forming the sound holes, and to form insulative blocks on the connection portions of the seed layer. Thereafter, perform the metallic layer plating process, and then remove the substrate, the insulative blocks and the seed layer. 
         [0012]    The preparation of the metallic plate having multiple through holes on the bridge portion thereof reduces the material consumption and stress-induced deformation, facilitating the follow-up cutting process. 
         [0013]    Based on the spirit of the present invention, during the preparation of the metallic plate, the seed layer can be made having the protrusions and the connection portions by means of: forming on the substrate a release layer having an array of protrusions and connection portions that connect the protrusions and then forming the seed layer on the release layer, or alternatively, forming a release layer on a substrate having an array of protrusions and connection portions connecting the protrusions and then forming the seed layer on the release layer. 
         [0014]    Further, the substrate can be selected from the group of silicon substrate, metallic substrate, glass substrate and plastic substrate; the release layer can be selected from the group of thermal tape, UV tape, photoresist, metal material and dielectric material; the seed layer can be selected from the group of chromium/copper (Cr/Cu), titanium/copper (Ti/Cu) and titanium tungsten/copper (TiW/Cu); the metallic layer can be selected from the group of nickel (Ni), copper (Cu) and nickel-chrome alloy (NiCo); the insulative blocks can be prepared using photoresist. 
         [0015]    Further, the metallic plate can be prepared using die-casting or stamping techniques. 
         [0016]    Other and further benefits, advantages and features of the present invention will be understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference characters denote like elements of structure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a manufacturing flow chart of a manufacturing method of electronic packaging in accordance with the present invention. 
           [0018]      FIG. 2  is a schematic drawing illustrating the manufacturing method of electronic packaging of  FIG. 1 . 
           [0019]      FIG. 3  is a manufacturing flow chart of a metallic plate preparation process for the manufacturing method of electronic packaging in accordance with the present invention, wherein each cover portion of the metallic plate provides a sound hole. 
           [0020]      FIG. 4  is a manufacturing flow chart of an alternate form of the metallic plate preparation process for the manufacturing method of electronic packaging in accordance with the present invention, wherein the metallic plate provides cover portions without any sound hole. 
           [0021]      FIGS. 5-10  are schematic drawings, illustrating the preparation of the metallic plate shown in  FIG. 2 . 
           [0022]      FIG. 11  is similar to  FIG. 6  but illustrating the relative positioning between the insulative blocks formed on the seed layer and the insulative blocks for the cover portions. 
           [0023]      FIGS. 12A and 12B  are schematic drawings illustrating multiple through holes formed in the bridge portion of the metallic plate. 
           [0024]      FIG. 13  is similar to  FIG. 5  but illustrating the configuration of the protrusion array on the release layer. 
           [0025]      FIG. 14  is similar to  FIG. 5  but illustrating the configuration of the protrusion array on the substrate. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    Referring to  FIGS. 1 and 2 , a manufacturing method in accordance with the invention is adapted for manufacturing, for example, but not limited to, MEMS (MicroElectrical-Mechanical System) microphone packages. This manufacturing method includes the following steps: 
         [0027]    At first, in step S 1 , prepare a metallic plate  10 , which comprises a plurality of cover portions  13  arranged in an array, each cover portion having a sound hole  11  for the passing of sound waves, and a bridge portion  15  connecting the cover portions  13 . There are no special restrictions on the material of the metallic plate  10 . Materials commonly seen in electronic packaging can be selectively used. 
         [0028]    According to this embodiment, the metallic plate  10  is prepared by using the method illustrated in  FIG. 3  and  FIGS. 5-10 . Detailedly speaking, the preparation of the metallic plate  10  includes sub-steps of S 11 - 15 , as shown in  FIG. 3 . During sub-step S 11 , as shown in  FIG. 5 , forming a release layer  51  on the surface of a substrate  50 , and then forming an array of spaced insulative blocks  53  on the release layer  51 . The substrate  50  can be a silicon substrate, metallic substrate, glass substrate or plastic substrate. Preferably, the substrate  50  is a silicon substrate. The release layer  51  can be selected from the group of thermal tape, UV tape, photoresist, metal material and dielectric material. The insulative blocks  53  are preferably prepared using photoresist. 
         [0029]    Thereafter, proceed to sub-step S 12 . During sub-step S 12 , as illustrated in  FIG. 5 , form a seed layer  55  on the release layer  51  and the insulative blocks  53 , enabling the seed layer  55  to provide a plurality of protrusions  551  corresponding to the insulative blocks  53  for forming the said cover portions  13  and a plurality of connection portions  553  connected with the protrusions  551  for forming the said bridge portion  15 . At this time, the material for the seed layer  55  is preferably selected from the group of chromium/copper (Cr/Cu), titanium/copper (Ti/Cu) and titanium tungsten/copper (TiW/Cu). 
         [0030]    Thereafter, proceed to sub-step S 13 . During sub-step S 13 , as illustrated in  FIG. 6 , form a plurality of insulative blocks  57  on the protrusions  551  of the seed layer  55  for forming the said sound holes  11 . At this time, these insulative blocks  57  are preferably prepared using photoresist, and the size of these insulative blocks  57  must be relatively smaller than the size of the aforesaid insulative blocks  53 . 
         [0031]    Thereafter, proceed to sub-step S 14 . During sub-step S 14 , as illustrated in  FIG. 7 , electroplate a metallic layer  59  on the seed layer  55  for forming the aforesaid metallic plate  10 , leaving the insulative blocks  57  exposed to the outside. At this time, the metallic layer  59  is preferably selected from the group of nickel (Ni), copper (Cu) and nickel-chrome alloy (NiCo). Thereafter, proceed to the last sub-step S 15 , during this last sub-step S 15 , remove the substrate  50  and the release layer  51  (see  FIG. 8 ), and then remove the insulative blocks  53             57  (see  FIG. 9 ), and then remove the seed layer  55  (see  FIG. 10 ), thereby obtaining the desired metallic plate  10 , which comprises an array of cover portions  13  each cover portion provided with a sound hole  11 , and a bridge portion  15  connecting the cover portions  13 . There are no special restrictions on removing the insulative  53 ; 57  and the seed layer  55 . Removing the insulative  53             57  and the seed layer  55  can be achieved using conventional techniques, for example, using a stripper to remove the insulative  53 ; 57  and employing an etching technique to remove the seed layer  55 . 
         [0032]    After preparation of the metallic plate  10 , proceed to step S 2 . During step S 2 , as shown in  FIGS. 1 and 2 , solder the metallic plate  10  to a circuit board  20  having a plurality of encapsulated areas (not shown) corresponding to the cover portions  13 , enabling the cover portions  13  to cover the respective encapsulated areas. During this step, the metallic plate  10  is soldered to a circuit board  20  by means of (but not limited to) applying a solder  30 , for example, tin paste to the metallic plate  10  and then employing a reflow soldering technique. In actual practice, the solder material  30  can also be applied to the circuit board  20 . 
         [0033]    At final, proceed to step S 3 . During step S 3 , cut the metallic plate  10  and the circuit board  20  along the bridge portion  15 , thereby obtaining multiple electronic packages  40 . 
         [0034]    Because the aforesaid embodiment is an example of the present invention for manufacturing MEMS (MicroElectrical-Mechanical System) microphone packages, each cover portion  13  of the metallic plate  10  must provide a sound hole  11  for the passing of sound waves. However, in actual application, the metallic plate  10  can be prepared without the aforesaid sound holes  11 . Detailedly speaking, the preparation of the metallic plate  10  can be alternatively achieved subject to the manufacturing flow chart shown in  FIG. 4 . After formation of the structure shown in  FIG. 5  subject to the sub-steps of S 11  and S 12 , proceed to sub-step S 13 ′ to electroplate a metallic layer  59  on the seed layer  55 , and then proceed to sub-step  14 ′ to remove the substrate  50  and release layer  51 , the insulative blocks  53  and the seed layer  55 , thereby obtaining the desired metallic plate  10 . 
         [0035]    It is to be noted that the configuration of the metallic plate  10  used in the manufacturing method of the present invention is not limited to the aforesaid example. In other alternate forms shown in  FIGS. 12A and 12B , the metallic plate  10  further comprises a plurality of through holes  17  located on the bridge portion  15  to reduce material consumption for the metallic layer  59  for forming the metallic plate  10  and the stress-induced deformation in soldering the metallic plate  10  to the circuit board  20 , facilitating the follow-up cutting process. 
         [0036]    In more detail, perform sub-steps S 11 -S 13  to form the structure shown in  FIG. 6 , and then, as shown in  FIG. 11 , form insulative blocks  58  on the connection portions  553  of the seed layer  55  for forming the through holes  17  (only on insulative block is shown in the drawing), and then electroplate the metallic layer  59  on the seed layer  55  for forming the aforesaid metallic plate  10 , leaving the insulative blocks  57 ; 58  exposed to the outside, and then remove the substrate  50 , the release layer  51 , the insulative blocks  53 ; 57 ; 58  and the seed layer  55 , thereby obtaining the desired metallic plate  10 , as shown in  FIGS. 12A and 12B . Further, the through holes  17  can be, but not limited to, circular or oblong through holes configured subject to the configuration of the insulative blocks  58 . 
         [0037]    Further, during the preparation of the metallic plate  10 , the seed layer  55  can be made to provide the protrusions  551  and the connection portions  553  subject to the following procedures. In more detail, as shown in  FIG. 13 , the release layer  51 ′ that is formed on the substrate  50  comprises a plurality of protrusions  511  arranged in an array and a plurality of connection portions  513  connecting the protrusions  511 . After formation of the release layer  51 ′on the substrate  50 , form the seed layer  55  on the release layer  51 ′, wherein the seed layer  55  comprises a plurality of protrusions  551  corresponding to the protrusions  511  of the release layer  51 ′, and a plurality of connection portions  553  corresponding to the connection portions  513  of the release layer  51 ′. Alternatively, as shown in  FIG. 14 , use a substrate  50 ′ comprising an array of protrusions  501  and a plurality of connection portions  503  connecting the protrusions  501 , and then form the seed layer  55  on the release layer  51 , wherein the seed layer  55  comprises a plurality of protrusions  551  corresponding to the protrusions  511  of the release layer  51 , and a plurality of connection portions  553  corresponding to the connection portions  513  of the release layer  51 . 
         [0038]    It is to be noted that the preparation of the metallic plate  10  is not limited to the aforesaid methods; die-casting or stamping techniques may be employed to make the metallic plate  10 . 
         [0039]    In conclusion, the invention is to directly stack a metallic cover array-like metallic plate  10  having an array of cover portions  13  on a printed circuit board having multiple encapsulating areas. When compared to conventional techniques, the invention enables multiple cover portions to be accurately positioned on a printed circuit board, effectively shortening the manufacturing time, reducing the manufacturing cost and simplifying the manufacturing process. 
         [0040]    Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.