Abstract:
A cleaning substrate for cleaning and regenerating a mold is disclosed. The mold is contaminated after repeatedly packaging the semiconductor device by making use of thermosetting resin. At least a protrusion of the substrate can substantially match with and be contained within the edges of the mold cavity of the mold when the cleaning substrate is placed in the mold.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates to a cleaning substrate for cleaning and regenerating a mold, and more particularly, to a cleaning substrate for cleaning a mold of a semiconductor package that can save the amount of the usage of the cleaning compound without changing the facilities of the original fabrication process.  
       BACKGROUND OF THE INVENTION  
       [0002]     During the encapsulating process by making use of the mold for molding the encapsulant of thermosetting resin, the mold releasing agent contained in the encapsulant of thermosetting resin can seep into the inner surface of the mold in order to release the mold. However, the mold-releasing characteristic of the molding parts will be deteriorated and the molding parts will be damaged cosmetically resulting from the continuously repeating the encapsulating process. Consequently, the material layer is contaminated and the mold releasing agent become less effective.  
         [0003]     To resolve the above-mentioned problems, cleaning work must be undertaken to remove the contaminated material layer that makes the mold-releasing agent ineffective. For example, an encapsulant made of thermosetting melamine resin is put in the mold so as to make the contaminated material, which is positioned on the inner surface of the mold, integrally form and solidify in order to be removed, thereby, the inner surface of the mold is cleaned.  
         [0004]      FIG. 1  and  FIG. 2  disclose a conventional semiconductor mold. As shown in  FIG. 1  and  FIG. 2 , the semiconductor mold  10  has a pot  11  for storing encapsulant. The pot  11  is connected to a mold cavity  14  through a runner  12  and a gate  13  where the mold cavity  14  is employed for placing semiconductor chip (not shown). When packaging a semiconductor chip, a plunger  15  is employed to press downward so as to compress the encapsulant that is liquidized to flow through the runner  12  and the gate  13 , and then fill the mold cavity  14  so as to encapsulate the semiconductor chip. Thereafter, the mold  10  is opened and the molded products are taken out after the encapsulant material is hardened.  
         [0005]     However, after the above-mentioned steps are continuously performed, a contaminated material layer is generated on the inner surface of the mold  10 . Especially, the contaminated material layer on the inner surface of the mold cavity  14  will cosmetically damage the molded products. Therefore, it is necessary to clean the contaminated material layer of the mold  10 . As shown in  FIG. 2 , when cleaning the mold  10 , a cleaning substrate  20  is put into the mold  10 , and a cleaning compound is injected into the mold cavity  14 . As the cleaning compound is solidified, it will integrally form with the contaminated material layer on the inner surface of the mold cavity  14  and the cleaning substrate to become a plastic mold which is then taken out of the mold cavity  14 . The inner surface of the mold will be entirely cleaned after repeating the above-mentioned action for around 10 to 15 times.  
         [0006]     It is noted that the cleaning substrate  20  is generally designed in the shape of a plate that can not effectively reduce the volume of the mold cavity  14  such that it takes several times for mold injecting to fill the mold cavity  14  of the mold  10 . As a result, it unnecessarily wastes the material of the cleaning compound.  
         [0007]     In the light of the above-mentioned disadvantages, it is necessary to provide a cleaning substrate for cleaning the mold of the semiconductor package that can save the amount of the usage of the cleaning compound without changing the facilities of the original fabrication process.  
       SUMMARY OF THE INVENTION  
       [0008]     It is an object of the present invention to provide a cleaning substrate for cleaning the mold of the semiconductor package that can save the amount of the usage of the cleaning compound.  
         [0009]     To achieve the above object, the present invention provides a cleaning substrate for cleaning and regenerating a mold. A protrusion provided on the substrate can substantially match with and be contained within the edges of a mold cavity of the mold when the cleaning substrate is placed in the mold while the mold is contaminated after repeatedly packaging the semiconductor device.  
         [0010]     In another aspect of the cleaning substrate according to the present invention, the profile of the protrusion is corresponding to the edges of the mold cavity.  
         [0011]     In one other aspect of the cleaning substrate according to the present invention, the cleaning substrate is made of paper.  
         [0012]     In addition, a cleaning method provided by the present invention for cleaning a mold includes the following steps: 
        (a) providing a mold having at least a mold cavity;     (b) placing a cleaning substrate in the mold cavity wherein the cleaning substrate has at least a first protrusion that can substantially match and be contained within the edges of the mold cavity;     (c) injecting a cleaning compound into the mold cavity of the mold;     (d) hardening the cleaning compound such that the cleaning compound is integrally formed with the cleaning substrate to become a molding product; and     (e) taking the molding product out of the mold cavity by opening the mold.        
 
         [0018]     According to the cleaning substrate of the present invention for cleaning semiconductor package, when cleaning the mold, a cleaning substrate is put into the mold. The multiplicity of protrusions of the cleaning substrate can be substantially contained within the edges of the multiplicity of mold cavities of the mold. Then, a cleaning compound is injected into the mold cavity. The cleaning substrate can reduce the amount of usage for mold injection since the protrusions are provided on the cleaning substrate to reduce the volume of the cavity 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0019]      FIG. 1  is a top view of a conventional cleaning substrate for a mold.  
         [0020]      FIG. 2  is a partial cross-sectional view of a conventional cleaning substrate for a mold of  FIG. 1 .  
         [0021]      FIG. 3  is a top view of the cleaning substrate for a mold according to the preferred embodiment of the present invention.  
         [0022]      FIG. 4  is a partial cross-sectional view of a cleaning substrate for a mold according to the preferred embodiment of the present invention of  FIG. 3 .  
         [0023]      FIG. 5  is a partial cross-sectional view of a cleaning substrate for a mold according to another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0024]     Currently, manufacturers in the field of semiconductor generally make use of the conventional transfer molding to form an encapsulating member for packaging the chip and the substrate. Normally, a molding apparatus connecting to the mold cavity through a runner and a gate includes a pot for placing the encapsulant. Besides, the molding apparatus provides a plurality of eject pins for ejecting the molding products out of the mold cavity.  
         [0025]     As for the molding process, firstly, the substrate with semiconductor chips attached thereon is placed into the molding apparatus. Then, the encapsulant is put in the pot with mold tightly clamped. Subsequently, a plunger in the pot is pushed to compress the encapsulant to flow through the runner and the gate so as to fill the mold cavity and encapsulate the chips and the substrate. After the encapsulant is entirely filled up the cavity, the plunger is kept still for a predetermined period of time till the encapsulant become hardened. Afterwards, the plunger is pulled up, the mold is opened, a degating process is performed, and the molding product is ejected by the use of the eject pin. However, after continuously repeating the above-mentioned processes, a contaminated material layer is generated on the inner surface of the mold.  
         [0026]      FIG. 3  and  FIG. 4  show a cleaning substrate for a semiconductor mold  100  according to the preferred embodiment of the present invention. As shown in  FIG. 3 , and  FIG. 4 , the semiconductor mold  100  is applicable for making semiconductor devices having printed circuit board (PCB) such as ball grid array (BGA). The mold  100  includes an upper mold  110   a  having a plurality of recesses  111  and a lower mold  110   b . When the upper mold  110   a  and the lower mold  110   b  are closed, a mold cavity  120  is formed therebetween at the recesses  111 . In addition, the mold  100  has a plurality of pots  130 , a plurality of runners  140 , and a plurality of gates  150  where the pots are connected to the mold cavities  120  through the runners  140  and gates  150 .  
         [0027]     As shown in  FIG. 4 , when cleaning the mold  100 , the mold  100  is tightly clamped to have the cleaning substrate  200  containing in the mold cavities  120 . A plurality of first protrusions  210 , preferably made of paper, are provided on the top surface of the cleaning substrate  200  and are integrally formed thereof. Each of the protrusions  210  is entirely contained within the edges of the mold cavities  120  of the mold  100  respectively. Moreover, the profile of each the protrusion  210  is preferably corresponding to the edge of each recess  111  of the mold cavity  120  respectively. Then, a cleaning compound, such as a thermosetting melamine resin, stored in the pots  130  and compressed by a downward pushing plunger  160  flows through the runner  140  and gate  150 , fills the mold cavities, and also forms over the top surface of the cleaning substrate  200 . After the cleaning compound is hardened to have the cleaning compound, the contaminated material layer and the cleaning substrate  200  all integrally formed together to become a molding product, the mold  100  is opened to have the molding products taken out. In this way, the contaminated material layer is removed from the inner surface of the mold cavity  120 . Since the substrate  200  is provided with the protrusion  210  that can effectively reduce the volume of the mold cavity  120 , the saving of the amount of usage of cleaning compound can be achieved.  
         [0028]      FIG. 5  is a cleaning substrate for a mold according to another embodiment of the present invention. As shown in  FIG. 5 , the semiconductor mold  100  is applicable for making semiconductor devices having lead frame such as quad flat package (QFP), thin small outline package (TSOP) etc. The mold  100  includes an upper mold  110   a  having a plurality of first recesses  111   a , and a lower mold  110   b  having a plurality of second recesses  111   b . The upper mold  111   a  and the lower mold  110   b  are tightly compressed to close each other such that the first recess  111   a  and the second recess  111   b  are combined to form a mold cavity  120   a . In addition, the mold  100  has a plurality of pots  130 , a plurality of runners  140 , and a plurality of gates  150  where each of the pots  130  are connected to each of the mold cavities  120  through each of the runners  140  and each of the gates  150  respectively.  
         [0029]     As shown in  FIG. 5 , when cleaning the mold  100 , the mold  100  is tightly clamped to have the cleaning substrate  200  containing in the mold cavities  120   a . A plurality of first protrusions  210   a  and second protrusion  210   b , both preferably made of paper, are provided on the top and the bottom surfaces of the cleaning substrate  200  respectively, and are integrally formed thereof respectively. Both of the protrusions  210   a  and  210   b  are substantially matched with and contained within the edges of each of the first recesses  111   a  and the second recesses  111   b  of the mold cavities  120   a  of the mold  100  respectively. Moreover, the profiles of each the first protrusions  210   a  and each of the second protrusion  210   b  are preferably corresponding to the edges of each of the first recesses  111   a  and the second recesses  111   b  of the cavities  120   a  respectively. Next, a cleaning compound, such as a thermosetting melamine resin, is stored in the pots  130 . The cleaning compound compressed by a downward pushing plunger  160  flows through the runner  140  and gate  150 , and fills the mold cavities  120   a , and also forms over the top surface of the cleaning substrate  200 . After the cleaning compound is hardened to have the cleaning compound, the contaminated material layer, and the cleaning substrate  200  all integrally formed together to become a molding product, the mold  100  is opened to have the molding products taken out. In this way, the contaminated material layer is removed from the inner surface of the mold cavity  120   a . Since the substrate  200  is provided with the protrusions  210   a  and  210   b  that can effectively reduce the volume of the mold cavity  120   a , the saving of the amount of usage of cleaning compound can be achieved.  
         [0030]     Although the present invention has been explained in relation to its preferred embodiments, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.