Flat Lead Frame Insulating Sheet Geometry
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Solution Overview
Problem
Semiconductor devices face challenges in achieving both effective insulation and heat dissipation between a lead frame and a heat dissipation plate without incurring higher manufacturing costs, as varying lead frame thickness improves heat dissipation and insulation but is costly, and a flat lead frame lacks stability and insulation when not bent.
Innovation Solution
A semiconductor device design featuring a flat lead frame within a sealing resin, where the insulating sheet is inclined and lowered to create a larger creepage distance between the lead frame and heat dissipation plate, ensuring insulation and heat dissipation without the need for costly bending processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lead frame is made with varying thickness to improve heat dissipation and insulation, then heat dissipation characteristics and insulation performance are improved, but manufacturing cost increases
Solution Approach 1:
The insulating sheet is designed with local quality variation through its inclined and lowered end region, creating different thickness zones. The main region maintains sufficient thickness for insulation, while the end region is reduced to allow sealing resin penetration, achieving both insulation performance and heat dissipation without varying the lead frame thickness
Solution Approach 2:
The sealing resin acts as an intermediary substance that penetrates into the end region between the insulating sheet and lead frame. This intermediary material provides the necessary insulation in critical areas while allowing the lead frame to maintain uniform thickness, thus improving heat dissipation without increasing manufacturing complexity
2Reliability
If the lead frame is bent to extend in different directions to improve insulation, then creepage distance is increased, but the lead frame becomes unstable during installation requiring additional positioning steps
Solution Approach 1:
Instead of bending the lead frame in the horizontal plane to increase creepage distance, the solution moves to the vertical dimension by lowering the end region of the insulating sheet. This dimensional shift allows the lead frame to remain flat and stable during installation while still achieving the required insulation distance through the vertical profile change of the insulating sheet
3Ease of manufacture
If a flat lead frame is used to simplify manufacturing, then manufacturing cost is reduced, but creepage distance cannot be ensured reducing insulation performance
Solution Approach 1:
The insulating sheet is designed with local quality variation through its inclined and lowered end region, creating different thickness zones. The main region maintains sufficient thickness for insulation, while the end region is reduced to allow sealing resin penetration, achieving both insulation performance and heat dissipation without varying the lead frame thickness
Solution Approach 2:
The sealing resin acts as an intermediary substance that penetrates into the end region between the insulating sheet and lead frame. This intermediary material provides the necessary insulation in critical areas while allowing the lead frame to maintain uniform thickness, thus improving heat dissipation without increasing manufacturing complexity
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 enhances insulation and heat dissipation characteristics between the lead frame and heat dissipation plate while reducing manufacturing costs by maintaining a flat lead frame and optimizing the insulating sheet's geometry, improving processability and handleability.
Implementation Method 1
The surface of the insulating sheet in contact with the lead frame is inclined and lowered to move away from the lead frame in an end region including at least a portion of an outermost end in plan view of the insulating sheet
Implementation Method 2
The sealing resin enters a region between the lead frame and the insulating sheet in the end region
Implementation Method 3
a ceramic substrate that combines thermal conductivity and insulation properties is often used in such a semiconductor device
Implementation Method 4
an insulating sheet arranged to cover the upper surface of a heat dissipation plate improves efficiency of thermal conduction from a lead frame to the heat dissipation plate while ensuring electrical insulation between the lead frame and the heat dissipation plate
Data Source
AI summary
A lead frame extends from inside a sealing resin to outside the sealing resin, and is placed to make contact with a main surface of an insulating sheet opposite to a heat dissipation plate. A semiconductor element is jointed to at least a portion of a main surface of the lead frame opposite to the insulating sheet within the sealing resin. The surface of the insulating sheet in contact with the lead frame is inclined and lowered to move away from the lead frame in an end region including at least a portion of an outermost end in plan view of the insulating sheet. The sealing resin enters a region between the lead frame and the insulating sheet in the end region. The lead frame is flat at least within the sealing resin.