Abstract:
A flat plate mold with special treatment or a metallic flat plate mold is adopted to flatten the resin painted over on IC chips during package dispensing process, such that it is able to maintain a consistent flatness of the surface of IC products after dispensing for laser or ink marking. And heat sinks can be attached to the flat plate mold to increase the heat-dissipating rate of IC products after dispensing.

Description:
FIELD OF THE INVENTION  
         [1]    1. The present invention relates to an improvement of IC package, and more particularly to the use of a flat plate mold with special treatment during IC package dispensing process, such that it is able to improve the surface flatness of an IC product after dispensing; and a heat sink can be attached to the flat plate mold to improve the heat-dissipating problem of IC product.  
         BACKGROUND OF THE INVENTION  
         [2]    2. In traditional plastic ball grid array (PBGA) package dispensing process, the surface of an IC package is not so smooth as that of a molding process.  
           [3]    3. Please refer to FIG. 1, which shows the traditional manufacturing processes of a liquid encapsulated plastic ball grid array, and has steps as below:  
           [4]    4. ( 1 . 1 ) Preparation of a substrate  1   
           [5]    5. ( 1 . 2 ), Mounting IC chip  2  (die attach)  
           [6]    6. ( 1 . 3 ) Bonding wire  3   
           [7]    7. ( 1 . 4 ) Dispensing liquid dam resin  4   
           [8]    8. ( 1 . 5 ) Filling liquid resin  5   
           [9]    9. ( 1 . 6 ) Mounting balls  6   
           [10]    10. Due to the surface tension of liquid resin  5 , it is possible to form an arc or spherical shape on the surface of resin  5  after solidification. The non-flatness of the resin surface will directly affect the quality of laser marking or ink marking. Also in traditional IC package dispensing process, there is no such a way of attaching heat sink. Therefore, the heat dissipation of a dispensing-type product will become a serious problem.  
         OBJECTS OF THE INVENTION  
         [11]    11. Therefore, one of the objects of the present invention is to adopt a flat plate mold with special coating treatment to flatten resin surface of IC package, such that the surface flatness of a dispensing-type IC product will be improved. The coating of flat plate mold is teflon or any other coatings which are hard to adhere with liquid resin. A vent or pin one dot is provided on the flat plate mold for venting away of liquid resin, solvent or diluent to avoid generation of voids. The pin one dot is used for recognition for a surface mount device. Therefore, after removing the flat plate mold, it is adapted to a marking process of the resin surface of IC package. A convex point will be formed on the resin surface simultaneously, which can be used as a marker for pin one dot.  
           [12]    12. Another object of the present invention is to adopt a metal flat plate mold, and in particular, to be designed with a heat sink. After the metal flat plate mold flattens the resin surface, the heat sink can contact with or approach to IC chip for heat dissipation. The metal flat plate is provided with a vent or pin one dot, and its inner surface can be treated by roughening or protruding process to increase the adhesion between heat sink and resin, and prevent from delamination.  
           [13]    13. A further object of the present invention is to adopt a flat plate mold structure with special design for the dispensing manufacturing of matrix array package (MAP). On the special flat plate mold, a vent or pin one dot has been provided for each IC in MAP respectively, to be adapted for the package of multiple chip modules (MCM) to increase the productivity of the process and raise the yield of the product.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [14]    14.FIG. 1 is a process drawing of the formation of a traditional PBGA liquid dispensed package;  
         [15]    15.FIG. 2 is a process drawing of a first embodiment of the liquid dispensed package of the present invention;  
         [16]    16.FIG. 3 is process drawing of a second embodiment of the liquid dispensed package of the present invention;  
         [17]    17.FIG. 4 is a process drawing of a third embodiment of the liquid dispensed package of the present invention;  
         [18]    18.FIG. 5 is a process drawing of a fourth embodiment of the liquid dispensed package of the present invention;  
         [19]    19.FIG. 6 is a process drawing of a fifth embodiment of the liquid dispensed package of the present invention;  
         [20]    20.FIG. 7A and FIG. 7B are schematic views of the inner surface on the flat plate mold after roughening or protruding treatment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [21]    21. Please refer to FIG. 2, it is a process drawing of a first embodiment of a liquid dispensed package of the present invention. After filling the thermosetting liquid resin  5  but before being solidified, a flat plate mold  7  with a special treatment surface is adopted (step  2 . 1 ) to flatten the resin  5  (step  2 . 2 ). The flat plate mold  7  is pressed over on resin  5 , and is provided with a vent  71  or pin one dot at proper position (we can design several air vents  71  if necessary), therefore it can smoothly vent away the extra resin  5  and air. After the resin  5  is solidified and the flat plate mold  7  is removed (step  2 . 3 ), a marker of pin one dot will be left on the resin surface. Finally, balls  6  are mounted on the back of the substrate  1  (step  2 . 4 ). The shape of flat plate mold that fits with the shape of resin, can be circular or polygon. This method can be applied to flatten the epoxy resin of either cavity up or cavity down PBGA package.  
         [22]    22. Please refer to FIG. 3, it is a process drawing of a second embodiment of a liquid dispensed package of the present invention. After filling the thermosetting resin  5  but before being solidified (step  3 . 1 ), a flat plate mold  7 ′ with a special treatment surface is adopted to flatten the resin  5  (step  3 . 2 ), but the flat plate mold  7 ′ can be bent downward at the dam resin  4  to cover the substrate  1 . The flat plate mold  7 ′ is pressed over on resin  5 , and is provided with an upper air vent  71 ′ or pin one dot at proper position (we can design several air vents  71 ′ if necessary); a lower side vent  72 ′ is provided at where the flat plate mold  7 ′ being bent downward to cover the substrate  1  (we can design several air vents  72 ′ if necessary), therefore extra resin  5  and air can be vented out smoothly, and resin  5  can be formed according to the shape of the flat plate mold  7 ′. After the resin  5  is solidified and the flat plate mold  7  is removed (step  3 . 3 ), a marker of pin one dot will be left on the resin surface. Finally, balls  6  are mounted on the back of the substrate  1  (step  3 . 4 ). The shape of flat plate mold that fits with the shape of resin, can be circular or polygon.  
         [23]    23. Please refer to FIG. 4, which is a process drawing of a third embodiment of liquid dispensed package of the present invention. After filling the thermosetting resin  5  but before being solidified, a flat plate mold  8  that is designed to have a metal heat sink  82  (step  4 . 1 ), is adopted to cover the resin  5  (step  4 . 2 ). The flat plate mold  8  is provided with a vent  81  or pin one dot at proper position (we can design several air vents  81  if necessary) to smoothly vent away the extra resin  5  and air. Resin  5  can be formed according to the shape of the flat plate mold  8 . The heat sink  82  is formed integrally or adhered with the flat plate mold  8 , and both are made of the same metal; the position of the heat sinks  82  is just corresponding to the IC chip in the resin  5 . When the flat plate mold  8  is pressed closely over the resin  5 , the heat sink  82  is just contacted or is very close to the IC chip  2 , therefore it will enhance the heat dissipation of the IC chip  2 . An inner surface  84  of the flat plate mold  8  is roughened or by protruding treatment (see FIG. 7A and FIG. 7B) to enhance the adhesion between flat plate mold  8 /heat sink  82  and resin  5 , and prevent from delamination. The flat plate mold  8  remains on the resin  5 , then balls  6  are mounted on back of the substrate  1  (step  4 . 3 ). The shape of flat plate mold that fits with the shape of resin, can be circular or polygon. This method can be adapted for the package flattening of a cavity up or cavity down of an IC package.  
         [24]    24. Please refer to FIG. 5, it is a process drawing of a fourth embodiment of a liquid dispensed package of the present invention. After filling the thermosetting resin  5  but before being solidified, a flat plate mold  8 ′, which is designed to have a metal heat sink  82 ′ (step  5 . 1 ), is adopted to cover the resin  5  (step  5 . 2 ). But the flat plate mold  8 ′ is bent downward at dam resin  4  to cover the substrate  1 . The flat plate mold  8 ′ is provided with an upper air vent  81 ′ or pin one dot at proper position (we can design several air vents  81 ′ if necessary). A lower air vent  83 ′ is provided at where the flat plate mold  8 ′ being bent downward to cover the substrate  1  (we can design several air vents  83 ′ if necessary), therefore extra resin and air can be vented out smoothly, and resin  5  can be formed according to the shape of the flat plate mold  8 ′. An inner surface  84  of the flat plate mold  8 ′ is roughened or by protruding treatment (see FIG. 7A and FIG. 7B) to enhance the adhesion between flat plate mold  8 ′/heat sink  82 ′ and resin  5 , and prevent from stripping. The flat plate mold  8  remains on the resin  5 , then balls  6  are mounted on back of the substrate  1  (step  5 . 3 ). The shape of flat plate mold that fits with the shape of resin, can be circular or polygon.  
         [25]    25. Please refer to FIG. 6, it is a process drawing of a fifth embodiment of a liquid dispensed package of the present invention, which is used for manufacturing of a matrix array package (MAP) in the dispensing packages process, and adopts a flat plate mold  9  of special matrix array package (MAP) design for the liquid dispensed packing (step  6 . 1 ). After filling the thermosetting resin  5  on the matrix array packaged IC chips  2 , but before being solidified, the special designed flat plate mold  9  is pressed over on the resin  5  (step  6 . 2 ). The flat plate mold  9  fits with those MAP IC chips  2 , and is provided with a vent  91  or pin one dot respectively for each IC to smoothly vent away extra resin  5  and air. If the flat plate  9  is with special treatment (i.e. painted with a layer of teflon or any other coating which is hard to adhere with the liquid resin), it will be removed after the resin  5  is solidified. If the flat plate mold  9  is designed by metal, many heat sinks  92  are designed respectively for each IC chip  2 , such that heat generated by each IC chip  2  can be smoothly vented away. These heat sinks can contact or approach the IC chip  2  (the one shown in FIG. 6 is a design of metal heat sink). An inner surface  84  of the flat plate mold  9  is roughened or by protruding treatment (see FIG. 7A and FIG. 7B) to enhance the adhesion between the flat plate mold  9 /heat sink  92  and the resin  5  to prevent from delamination. Then, balls  6  are mounted on back of the substrate (step  6 . 3 ), and after sawing of the substrate, many individual IC packages  10  are obtained (step  6 . 4 ).  
         [26]    26. One skilled in this art can make various alterations without departing from the spirit and scope of the present invention after reading the present invention. Therefore, the appended claims are intended to embrace all these variations.