Semiconductor Die Pad Stability via Three-Point Lead Frame Support
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Solution Overview
Problem
The challenge in semiconductor devices is to enhance the reliability and stability of die pads during assembly processes, such as die bonding and wire bonding, while reducing the number of support pins without increasing the device size, as fewer support pins lead to unstable die pad support and potential damage from external loads.
Innovation Solution
The semiconductor device manufacturing method involves a lead frame with three support pins integrally formed with each die pad, including a first support pin connected to an outer lead, a second support pin between inner leads connected to a tie bar, and a third support pin on a different side, ensuring three-point support and stability during assembly processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of support pins is reduced to increase the number of signal pins, then the number of pins for functional enhancement increases, but the die pad support stability deteriorates
Solution Approach 1:
The lead frame structure is designed to perform multiple functions: it provides both mechanical support for the die pad and electrical connection paths for signals. The outer leads serve dual purposes as both structural support elements and signal transmission conduits, eliminating the need for separate support pins and allowing increased signal pin count without compromising support stability
Solution Approach 2:
The invention merges the support function and signal transmission function into a single integrated lead frame structure. The outer leads that provide mechanical support are also configured to carry signal connections, combining what would traditionally be separate functional elements into one unified structure
2Volume of moving object
If the die pad size is reduced to match chip size, then the device size is minimized, but the coupling portion for support pins cannot be provided
Solution Approach 1:
The support function is extracted from the die pad structure itself and transferred to the lead frame. Instead of incorporating coupling portions into the die pad, the lead frame's outer leads are designed to provide support independently, allowing the die pad to be minimized to chip size without requiring additional coupling structures
Solution Approach 2:
The outer leads of the lead frame serve multiple functions: they provide mechanical support for the die pad, establish electrical connections, and eliminate the need for separate coupling portions on the die pad, enabling miniaturization while maintaining manufacturability
3Productivity
If external load is applied to the die pad during assembly, then the bonding and wire bonding processes can be performed, but the die pad deforms or vibrates vertically causing bonding failure
Solution Approach 1:
The lead frame structure is designed with enhanced rigidity and structural support specifically at the locations where the die pad is supported. The outer leads are configured to provide localized mechanical reinforcement that prevents vertical deformation and vibration during bonding operations, while maintaining flexibility in other areas for electrical connectivity
Data Source
AI summary
A semiconductor device includes a die pad, which includes an upper surface and a lower surface, the upper surface forming a rectangular shape in plan view; a plurality of support pins that support the die pad; a plurality of inner leads arranged around the die pad; a plurality of outer leads connected to each of the inner leads; a semiconductor chip which includes a main surface and a back surface and in which a plurality of electrode pads is formed in the main surface; a plurality of wires which electrically couple the electrode pads of the semiconductor chip to the inner leads respectively; and a sealing body that seals the support pins, the inner leads, the semiconductor chip, and the wires. A first support pin of the plurality of support pins is integrally formed together with the die pad. The first support pin is terminated inside the sealing body.