Abstract:
It is intended to provide high quality IC packages with the same size as that of IC chips. In a step of covering semiconductor chips with a resin for protection thereof, the resin is also allowed to adhere onto an opposite side of the substrate on which the semiconductor chips are mounted.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates generally to a method of forming IC packages in which a number of semiconductor chips are mounted on a substrate.  
           [0003]    2. Related Background Art  
           [0004]    When a number of semiconductor chips are mounted on a substrate and are covered with a resin to be protected, which then is divided into individual semiconductor packages, conventionally, the substrate warps due to the resin which is adhered onto only one side of the substrate as shown in FIG. 2.  
           [0005]    As shown in FIG. 2, since the resin is allowed to adhere onto only one side of the substrate, the substrate warps to one side. Hence, in the steps thereafter, it is necessary to work with consideration given to this warp. For instance, sufficient space should be provided so as to prevent upper-side and lower-side substrates from coming to contact with each other when a substrate is to be mounted on a magazine, or the focus of a microscope should be readjusted continuously in inspecting a substrate, which has required extra time and energy. In addition, when a substrate is cut and thereby semiconductor packages are obtained, such warp should be taken into account and the substrate cannot be cut with high precision.  
         SUMMARY OF THE INVENTION  
         [0006]    In order to solve the above-mentioned problems, in the present invention, when semiconductor chips mounted on a substrate are to be covered with resin, resin is also allowed to adhere onto the opposite side of the substrate on which the semiconductor chips are mounted. According to this, comparable levels of resin stress are exerted on respective sides of the substrate. Hence, the stresses exerted on the respective sides cancel each other out and thus the substrate does not warp. The resin that has adhered onto the opposite side of the substrate on which the semiconductor chips are mounted is removed before the substrate is cut. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    In the accompanying drawings:  
         [0008]    [0008]FIGS. 1A to  1 F show a manufacturing method of a semiconductor device according to the present invention; and  
         [0009]    [0009]FIG. 2 shows a conventional semiconductor device. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0010]    The present invention relates to a technique for preventing a substrate from warping in a method of manufacturing a semiconductor device including mounting of a number of semiconductor chips on the substrate, covering the semiconductor chips with resin, and dividing the whole into semiconductor packages. An example of the present invention is described with reference to the drawing as follows.  
         [0011]    [0011]FIG. 1 shows a manufacturing method of the present invention. FIG. 1A is a cross-sectional view illustrating a state where semiconductor chips  12  are mounted on a substrate  11  and wires inside the substrate  11  and the semiconductor chips  12  are connected with metal lines  14 . Examples of the substrate include a glass epoxy substrate, a ceramic substrate, a polyimide substrate, and the like.  
         [0012]    Next, as shown in FIG. 1B, the substrate  11  is placed inside a mold  17  and resins  15   a  and  15   b  are poured thereinto and then are solidified. Conventionally, resin was allowed to adhere onto the only side on which the semiconductor chips  12  were provided. In the present invention, however, the resins  15   a  and  15   b  are poured on both front and back sides of the substrate  11 , respectively. At this time, a tape  16  is interposed between the substrate  11  and the resin  15   b  on the side on which the semiconductor chips  12  are not provided. The mold  17  is removed after the resins  15   a  and  15   b  are solidified.  
         [0013]    [0013]FIG. 1C shows a state where the front and back sides of the substrate  11  are covered with the resins  15   a  and  15   b , respectively.  
         [0014]    Next, as shown in FIG. 1D, the face of the resin  15   a  on the side on which the semiconductor chips are provided is stuck onto a dicing tape  18 . Since the substrate  11  is not warped, it sticks to the dicing tape  18  easily.  
         [0015]    Next, the tape  16  is peeled off from the substrate  11 . At this time, the resin  15   b  on the tape side is also peeled off together. This state after the peeling off is shown in FIG. 1E.  
         [0016]    Afterward, the substrate is cut by dicing. Thus, as shown in FIG. 1F, a semiconductor package is obtained that is composed of the substrate  11 , the resin  15   a , and external electrodes  20 .  
         [0017]    As described above, since resin is allowed to adhere not only to the side on which the semiconductor chips are mounted but also to the opposite side thereto, the substrate does not warp and thus processes in the steps carried out thereafter can be proceeded easily with no problem being caused. Particularly, it is easy to stick the substrate to the dicing tape before the substrate is cut, and thus the substrate is allowed to adhere completely to the dicing tape to be stuck thereto. In addition, since a tape is interposed between the lower-side face of the substrate and resin on the lower side of the substrate, the resin on the lower side can be removed from the substrate relatively easily after the substrate is stuck to the dicing tape. It is also possible to peel off the tape and resin on the lower side of the substrate after individual semiconductor packages are obtained.  
         [0018]    The invention may be embodied in other forms without departing from the spirit or essential characteristics thereof. The embodiments disclosed in this application are to be considered in all respects as illustrative and not limiting. The scope of the invention is indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.