Wafer Circular Concavity Encapsulation for Semiconductor Packages
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Solution Overview
Problem
Conventional methods for producing semiconductor packages with multiple stacked chips require costly and complex mold-based encapsulation, leading to air trapped in the resin, potential wire breakage, and short-circuiting risks due to high pressure filling.
Innovation Solution
A method involving a semiconductor wafer with a circular concavity formed on one surface, allowing molten resin to be filled and cured without a mold, with via contact means and wire connections formed to prevent air entrapment and wire deformation, and the wafer cut into packages along lattice-patterned streets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mold is used to form the encapsulation resin, then the resin can be filled into the molding space, but the production cost increases and the production method becomes complicated
Solution Approach 1:
The patent removes the mold from the encapsulation process entirely. Instead of using a mold to form the encapsulation resin, the resin is directly filled onto the semiconductor chip stack and cured in place. This extraction of the mold eliminates the complexity of mold design, manufacturing, and maintenance while reducing production costs.
Solution Approach 2:
The semiconductor chip stack itself serves as the container for the encapsulation resin. The resin is applied directly to the chip stack and cures to form the encapsulation layer, with the chip stack's own structure defining the encapsulation boundaries. This self-service approach eliminates the need for external molding tools.
2Length of moving object
If the thickness of the molding space is made small to achieve thin packages, then air becomes difficult to discharge and may remain in the resin
Solution Approach 1:
Instead of trying to discharge air from the bottom up through a narrow molding space, the patent applies the resin from the top of the chip stack downward. The resin is dropped or dispensed onto the top surface and flows down to encapsulate the chips, allowing air to escape naturally during the curing process without requiring complex discharge mechanisms.
Solution Approach 2:
The patent replaces the mechanical mold-based filling system with a direct resin application method. The resin is applied in a controlled manner and cured in place, eliminating the need for mechanical air discharge systems and high-pressure filling mechanisms that would be required in traditional molding.
3Manufacturing precision
If high pressure is applied to fill the resin into the molding space, then the molding space becomes full of resin, but wire breakage or short-circuiting may occur
Solution Approach 1:
The patent replaces high-pressure mechanical filling with a low-pressure or gravity-assisted resin application method. The resin is applied directly to the chip stack and cures in place, eliminating the high pressures that would deform or break the fine wire bonds connecting the semiconductor chips.
Solution Approach 2:
The patent changes the pressure parameter from high (in mold filling) to low or atmospheric pressure (in direct application). This parameter change allows complete resin coverage without subjecting the delicate wire bonds to deforming forces, maintaining both filling completeness and wire integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables thin, air-free encapsulation without wire damage, reducing production costs and complexity, and ensuring reliable semiconductor packages without the need for a dedicated mold.
Implementation Method 1
filling a molten resin into the circular concavity of the semiconductor wafer, and curing the resin
Data Source
AI summary
A method for producing a semiconductor package including a main semiconductor chip having a semiconductor circuit formed on one surface thereof, at least one subsidiary semiconductor chip stacked on the other surface of the main semiconductor chip, and an encapsulation resin covering the subsidiary semiconductor chip. This method comprises a semiconductor wafer preparation step of preparing a semiconductor wafer, on whose one surface many rectangular regions are defined by streets, and in each of the rectangular regions of which a semiconductor circuit constituting the main semiconductor chip is disposed; a circular concavity formation step of forming a circular concavity in the other surface of the semiconductor wafer; a semiconductor chip stacking step of stacking at least one such subsidiary semiconductor chip on each of many rectangular regions on the bottom surface of the circular concavity; an encapsulation resin formation step of filling a molten resin into the circular concavity, and curing the resin, thereby forming an encapsulation resin covering the subsidiary semiconductor chips; and a separation step of cutting the encapsulation resin, together with the semiconductor wafer, along the streets, to separate the semiconductor wafer and the encapsulation resin into many of the semiconductor packages.