Thin Foil Semiconductor Package Carrier Cavities
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Solution Overview
Problem
Conventional integrated circuit packaging methods using leadframes face challenges such as warpage due to thin foil fragility and the high cost of supporting structures, as well as the incompatibility of existing equipment with thin foil-based designs.
Innovation Solution
A thin foil carrier structure with embossed cavities and pedestals is used to form electrical interconnects, where the foil is reshaped by molding material to create raised and recessed areas, allowing for the formation of contact pads without the need for backing tape or photolithography, and subsequent singulation into individual packages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the leadframe thickness is reduced to conserve metal and reduce package size, then material usage and package size are improved, but the leadframe becomes more prone to warpage during packaging
Solution Approach 1:
The foil is pre-formed with raised and recessed areas before packaging, so that the interconnect structure is already shaped to accommodate the die and wire bonds. This preliminary formation eliminates the need for post-packaging warpage compensation and allows thin foil to be used without suffering from warpage issues during the packaging process.
Solution Approach 2:
The invention replaces the traditional rigid leadframe structure with a thin, flexible foil that is molded into shape. Instead of relying on the mechanical rigidity of a thick leadframe to prevent warpage, the process uses molding to directly form the interconnect structure, substituting mechanical support with a shaping process that works specifically for thin materials.
2Ease of manufacture
If conventional leadframe packaging processes are used, then manufacturing experience and equipment compatibility are maintained, but the process is more expensive and less efficient due to the need for backing tape and complex steps
Solution Approach 1:
The invention extracts and eliminates the backing tape component from the packaging process. By forming the interconnect structure directly in the molding process without requiring a supporting backing tape, the process becomes simpler and more cost-effective while maintaining manufacturing reliability through direct formation of the functional interconnect structure.
Solution Approach 2:
The invention merges the interconnect formation process with the packaging molding process. Instead of separately creating the leadframe structure and then packaging it, the thin foil interconnects are formed directly within the packaging mold, combining multiple steps into one integrated process that improves both simplicity and reliability.
3Device complexity
If thin foil is used without backing tape support, then material cost and process complexity are reduced, but the foil becomes more fragile and difficult to handle
Solution Approach 1:
The invention changes the physical state and form of the thin foil through molding. By applying heat and pressure during the molding process, the foil is transformed from a fragile, flat sheet into a structurally sound three-dimensional interconnect structure with raised and recessed areas. This parameter change (from flat to molded) provides the necessary strength and handling robustness while eliminating the need for backing tape support.
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
This method conserves metal, reduces costs, and avoids the need for supporting structures, while enabling efficient processing of thin foils using standard packaging equipment, resulting in cost-effective and stable integrated circuit packages.
Implementation Method 1
The molding material presses against the foil, such that the shape of the foil follows some of the contours of the underlying cavities on the carrier. As a result, raised and recessed areas are formed in the foil.
Data Source
AI summary
An apparatus for incorporating a metallic foil into a semiconductor package includes a carrier embossed with a multiplicity of cavities. Each of the cavities define a pedestal recessed with the cavities which penetrate only partially through the thickness of the carrier. A metallic foil overlying a pattern with the pedestals in direct contact and help support the metallic foil with the metallic foil pressed into at least some of the cavities. In other embodiments, a gap is between the metallic foil and bottoms of the cavities in a substrate. Integrated circuit dice are attached to the foil. Each die is attached to the foil in a region of the foil overlying a portion of the at least one device area pattern. Bonding wires electrically connect the integrated circuit dice to the foil.