Lead Frame Manufacturing for Compact Semiconductor Packages
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Solution Overview
Problem
Semiconductor packages with large volumes are not compatible with the miniaturization trend in electronic products, necessitating a solution to reduce size while maintaining functionality.
Innovation Solution
A lead frame with a hollow rectangular structure, a central pad, and peripherally extending lead portions, formed by etching or stamping a metal plate, is used to create a quad flat non-leaded package, where the lead frame is integrated with a semiconductor package, reducing volume and enhancing waterproof capabilities through encapsulating material filling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a traditional semiconductor package structure is used, then the package can accommodate multiple chips, but the volume becomes large and incompatible with miniaturization
Solution Approach 1:
The patent implements chip stacking where the first chip is disposed on the substrate and the second chip is disposed on the first chip, creating a nested vertical arrangement. This nesting principle allows multiple chips to occupy a smaller footprint area by utilizing the vertical dimension, thereby reducing overall package volume while maintaining the capability to accommodate multiple chips.
Solution Approach 2:
The invention transitions from a planar horizontal arrangement of chips to a vertical three-dimensional stacking configuration. By utilizing the vertical dimension (Z-axis) for chip placement rather than only the horizontal plane, the package achieves miniaturization in the footprint area while accommodating multiple chips through vertical stacking, thus resolving the volume contradiction.
2Reliability
If the lead frame is exposed without encapsulation, then the structure remains simple, but waterproof capability is insufficient
Solution Approach 1:
The patent employs a mold compound that encapsulates the lead frame, chips, and bonding wires, forming a protective shell structure. This encapsulation layer acts as a waterproof barrier that protects the internal components from environmental moisture and contaminants, thereby improving reliability without significantly complicating the overall device structure.
Solution Approach 2:
The invention uses a composite structure combining the metal lead frame, semiconductor chips, bonding wires, and mold compound material. The mold compound material serves as a protective encapsulation layer that provides waterproofing and mechanical support, creating a composite package structure that enhances reliability while maintaining manufacturing feasibility.
Data Source
AI summary
A method of manufacturing a lead frame includes, firstly, forming a metal plate which has a frame portion, a pad portion for mounting semiconductor elements, and lead portions. After that, the lead portions are etched to form a support end, a connecting terminal and a jointing end of each lead portion. Then a receiving portion for receiving the semiconductor elements is formed, wherein the receiving portion is collectively defined by the connecting terminals, the support ends and the pad portion. After that, step portions are formed on the lead portions and the pad portion by half-etching. A method of manufacturing a semiconductor package which includes the lead frame is also provided.