Leadframe With Notched Chip Supporting Plate And Thin Lead Forming Plate
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Solution Overview
Problem
Conventional leadframes with uniform thickness struggle to provide adequate heat dissipation for high-power chips, leading to increased costs and prolonged manufacturing time when attempting to incorporate a thick chip supporting plate and thin lead forming plate.
Innovation Solution
A leadframe design featuring a chip supporting plate and a lead forming plate as individual components with a notch on the supporting plate, where the lead forming plate is thinner and connected via a connecting rod with solder points, allowing for separate rolling and laser welding to reduce manufacturing costs and stress release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional leadframe with uniform thickness is used, then the manufacturing process is simple, but the heat dissipation efficiency is insufficient for high-power chips
Solution Approach 1:
The leadframe applies different thickness specifications to different functional components: the chip supporting plate uses a first thickness (e.g., 0.5-1.0mm) for heat dissipation, while the lead forming plate uses a second thickness (e.g., 0.05-0.1mm) for flexibility and bonding. This local differentiation resolves the contradiction by optimizing each region for its specific function rather than using uniform thickness throughout.
2Temperature
If a leadframe with different thicknesses (thick chip supporting plate and thin lead forming plate) is provided, then the heat dissipation efficiency is improved, but the manufacturing costs increase and lead-time is prolonged
Solution Approach 1:
The leadframe is divided into two separately manufactured components: a chip supporting plate with first thickness and a lead forming plate with second thickness. These components are produced independently through rolling processes optimized for each thickness requirement, then assembled together. This segmentation allows each component to be manufactured efficiently at its optimal thickness without the complexity of producing a single multi-thickness component, thereby reducing overall manufacturing time and cost while maintaining the heat dissipation benefits.
3Strength
If the chip supporting plate and lead forming plate are connected rigidly, then the structural strength is high, but the stress concentration reduces the service life
Solution Approach 1:
A connecting rod serves as an intermediary element between the chip supporting plate and lead forming plate. This connecting rod provides structural connection while allowing stress distribution and release, preventing stress concentration at the junction. The intermediary connecting rod maintains structural integrity while accommodating thermal and mechanical stresses, thereby extending the service life of the leadframe.
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 design simplifies the manufacturing process, reduces costs and time, and extends the service life of the leadframe by releasing stresses and ensuring high-quality welding, while maintaining efficient heat dissipation.
Implementation Method 1
The end portion of the connecting rod is structurally connected to the notch of the chip supporting plate by laser welding
Data Source
AI summary
A leadframe including a chip supporting plate, a lead forming plate, and solder points is provided. A notch is formed on an edge of the chip supporting plate. The thickness of the lead forming plate is less than the thickness of the chip supporting plate. The lead forming plate has a main body, inner leads, and a connecting rod. The inner leads and the connecting rod are extended from an edge of the main body. The connecting rod has an end portion fitting the notch. The solder points are located at the boundary between the end portion and the notch for structurally connecting the connecting rod and the chip supporting plate.