Dual Downset Leadframe Layout for Reliable Semiconductor Package Interconnects
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Solution Overview
Problem
Existing semiconductor device packages face challenges in accommodating sophisticated features while maintaining reliability, performance, and minimizing costs.
Innovation Solution
A semiconductor device with a dual downset leadframe configuration, where leads are bent in a specific manner to allow for efficient encapsulation and exposure of lead pads and distal portions, enabling reliable connections to a printed circuit board and external components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional leadframe configuration is used, then the device structure is simple, but the reliability and performance are reduced when accommodating sophisticated semiconductor features
Solution Approach 1:
The leadframe is segmented into multiple functional zones: a first downset portion for coplanarity with the semiconductor die, a second downset portion for lead pad formation, and a distal portion for PCB attachment. This segmentation allows each portion to be optimized for its specific function, improving overall reliability while managing complexity through functional decomposition.
Solution Approach 2:
The leadframe transitions from a conventional planar configuration to a three-dimensional dual downset structure. The leads are bent downward at two distinct levels, creating vertical dimensionality that enables both coplanarity with the die and exposure of lead pads through the encapsulant, thereby improving reliability without excessive complexity.
2Reliability
If leads are configured for coplanarity with semiconductor die, then connection reliability improves, but encapsulation and lead pad exposure become difficult
Solution Approach 1:
The leadframe is divided into distinct segments with different vertical positions: the first downset portion achieves coplanarity with the die for reliable connections, while the second downset portion creates a lower plane that allows lead pads to be exposed through the encapsulant. This segmentation resolves the conflict between connection reliability and encapsulation ease.
Solution Approach 2:
The leadframe is pre-configured with dual downset portions before encapsulation. The first downset portion is positioned to ensure coplanarity with the die, and the second downset portion is positioned to allow encapsulant flow and lead pad exposure. This preliminary configuration simplifies the encapsulation process while maintaining connection reliability.
3Adaptability or versatility
If lead pads are exposed through encapsulant, then external component attachment is enabled, but manufacturing complexity increases
Solution Approach 1:
The leadframe structure is segmented to include a second downset portion that extends below the first downset portion. This lower segment positions the lead pads to be exposed through the encapsulant, enabling external component attachment. The segmentation allows this functionality to be achieved through structural design rather than additional manufacturing steps.
Solution Approach 2:
The dual downset leadframe configuration is self-forming during the encapsulation process. The encapsulant naturally flows around the downset portions, automatically exposing the lead pads without requiring additional masking or exposure steps. This self-service approach enables external component attachment capability while minimizing manufacturing complexity.
Data Source
AI summary
A semiconductor device is provided. The semiconductor device includes a leadframe having a plurality of leads. A first lead of the plurality of leads has a lead pad formed between a distal portion and a proximal portion of the first lead. A semiconductor die includes a plurality of bond pads located at an active side. Each bond pad of the plurality is connected to a respective lead of the plurality of leads. An encapsulant encapsulates the semiconductor die and at least a portion of the leadframe. A distal portion of each lead is exposed through the encapsulant at a first major side. The lead pad is exposed through the encapsulant at a second major side opposite of the first major side.