LED Lead Frame Reinforcement via Inclined Interconnects
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Solution Overview
Problem
Conventional lead frames for semiconductor devices with LED elements are prone to deformation due to the formation of elongated spaces between die pads and leads, which can lead to a slit blind or interdigitated shape during handling, causing short-circuiting issues.
Innovation Solution
A lead frame design with package regions arranged in multiple rows and columns, interconnected via dicing regions, where die pads and leads are connected by inclined reinforcement pieces and lead connecting portions, preventing spatial gaps and thus deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If die pads and leads are spaced apart to prevent short-circuiting, then electrical isolation is improved, but spatial gaps become connected forming elongated spaces that cause deformation
Solution Approach 1:
A resin layer is introduced as an intermediary substance between the die pads and leads. This resin fills the spatial gaps and connects the spaces, preventing the formation of continuous elongated spaces while maintaining the necessary electrical isolation. The resin acts as a mediator that simultaneously addresses both the electrical isolation requirement and the structural stability concern.
Solution Approach 2:
The physical state and properties of the spacing material are changed by using a resin that can be applied in liquid or paste form and then cured. This parameter change allows the resin to flow into and fill the gaps between die pads and leads, then solidify to provide structural support and prevent deformation, thereby transforming the lead frame from a vulnerable state to a stable state.
2Reliability
If tie bars are arranged in grid form to interconnect terminals, then electrical connectivity is improved, but the lead frame becomes prone to deformation into slit blind or interdigitated shape
Solution Approach 1:
The resin layer serves as an intermediary that fills the spaces created by the grid arrangement of tie bars and die pads. By filling these spaces, the resin prevents the lead frame from deforming into slit blind or interdigitated shapes while maintaining the electrical connectivity provided by the grid structure.
Solution Approach 2:
The lead frame structure is transformed into a composite system combining metal components (tie bars, die pads, leads) with a resin matrix. This composite structure leverages the electrical conductivity of the metal grid while the resin provides mechanical stability and prevents deformation, creating a synergistic structure that addresses both connectivity and stability requirements.
3Productivity
If spatial gaps between die pads and leads are reduced to increase mounting density, then productivity is improved, but the risk of short-circuiting and deformation increases
Solution Approach 1:
The resin layer acts as an intermediary that enables closer spacing between die pads and leads by filling the reduced gaps and preventing short-circuits. This allows higher mounting density to be achieved while maintaining electrical isolation, as the resin provides both physical separation and structural support even at reduced spacings.
Solution Approach 2:
The use of resin changes the parameters of the spacing system, allowing for reduced gap dimensions while maintaining reliability. The resin's ability to fill and solidify in small spaces enables tighter packaging of components, increasing mounting density without compromising electrical isolation or structural integrity.
Data Source
AI summary
A lead frame for mounting LED elements includes a frame body region and a large number of package regions arranged in multiple rows and columns in the frame body region. The package regions each include a die pad on which an LED element is to be mounted and a lead section adjacent to the die pad, the package regions being further constructed to be interconnected via a dicing region. The die pad in one package region and the lead section in another package region upward or downward adjacent to the package region of interest are connected to each other by an inclined reinforcement piece positioned in the dicing region.