2 steps curing encapsulant and 2 steps encapsulation
Original Publication Date: 2003-Sep-25
Included in the Prior Art Database: 2003-Sep-25
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The invention allows it to be used for molding of ICs (Integrated Circuits) which is an economically advantageous method for encapsulation of ICs. The new method combines the advantages of all methods available and the new material formulation can be incorporated in MAP molding. So, the invention solves the problem of wires sweep in ICs. The factors of causing sweep are the material, the process, the design and the equipment. One of the major causes of sweep is the flowability property of the encapsulant such as high viscosity, short gel time and spiral flow. Firstly, a small amount of encapsulant is dispensed onto the wire-bonded ICs from the top either by multi-head potting or top gate molding to minimize the perpendicular forces on the wire, which causes the wire to sweep or deflect. The encapsulant A is then set at B-stage by exposing to UV (ultra violet) or conventional thermal curing process to lock the wires in position. Conventional transfer molding is then carried out to completely encapsulate the whole pancake area on the substrate with encapsulant A. Subsequently, the substrate with the homogenous molded surface is sent for post-mold cure to ensure complete cross-linking of the polymer. Again, there is no additional material being introduced to the package thus reducing any risk of reliability issue.