Lead Frame Heat Sink Layout for Resin-Sealed Electronics
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Solution Overview
Problem
Electronic apparatuses with metal lead frames bonded to semiconductor components sealed with resin face challenges in heat dissipation due to the low thermal conductivity of the sealing resin, making it difficult to efficiently dissipate heat, especially when the components generate a significant amount of heat.
Innovation Solution
The electronic apparatus includes a metal lead frame with a heat sink and lead design where the lead frame has a surface bonded to the semiconductor component and partially exposed, allowing heat to be dissipated from the heat sink's exposed surface, and the semiconductor component is mounted on a wiring board with an insulating base and adhesive layer covered by sealing resin, enhancing heat transfer and dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lead frame and electronic component are entirely covered by sealing resin, then the electronic component is protected and sealed, but heat dissipation efficiency deteriorates due to the low thermal conductivity of the sealing resin
Solution Approach 1:
The patent applies local quality by exposing specific local regions of the lead frame (first and second exposed portions) while sealing other regions. This creates different functional zones: sealed areas for protection and exposed areas for heat dissipation. The selective exposure allows the lead frame to serve dual purposes - structural sealing support and thermal management pathway.
Solution Approach 2:
The sealing resin is segmented to cover only specific portions of the lead frame while leaving other portions exposed. This segmentation creates distinct functional regions within the sealing structure, allowing simultaneous achievement of sealing protection in covered areas and heat dissipation in exposed areas.
2Temperature
If heat dissipation is improved by exposing the lead frame, then thermal conductivity increases, but the sealing protection is reduced
Solution Approach 1:
Different regions of the lead frame are assigned different functions through selective sealing. The first and second exposed portions are left uncovered to optimize heat dissipation, while other portions are sealed for protection. This local differentiation resolves the contradiction by allowing both sealing and heat dissipation to occur simultaneously in different locations.
Solution Approach 2:
The sealing resin coverage is segmented rather than complete, creating distinct sealed and exposed regions. This segmentation enables the structure to fulfill multiple functions - the sealed portions provide protection while the exposed portions facilitate thermal management, thereby resolving the trade-off between sealing and heat dissipation.
3Reliability
If the wiring board is fully sealed with resin, then the electronic component is protected, but heat transfer from the component is impeded
Solution Approach 1:
The lead frame acts as an intermediary thermal pathway between the electronic component and the external environment. By exposing portions of the lead frame, heat can transfer from the component through the lead frame to the exposed surfaces, bypassing the thermal barrier of the sealing resin. The lead frame serves as a thermal mediator that enables heat dissipation while the sealing resin provides protection.
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 configuration improves heat dissipation efficiency by utilizing the high thermal conductivity of the metal lead frame and heat sink, effectively managing heat generated by the semiconductor components, even when the heat generation is substantial.
Implementation Method 1
thermal conductivity of the sealing resin is lower than thermal conductivity of the lead frame, so that heat dissipation efficiency is not much high
Implementation Method 2
a second surface to which the electronic component is bonded
Implementation Method 3
heat generated by the electronic component is dissipated from the lead frame or dissipated from the lead frame through the sealing resin
Data Source
AI summary
An electronic apparatus includes a lead frame, a wiring board, and a sealing resin. The wiring board mounts an electronic component boded to the lead frame. The sealing resin seals the lead frame, the electronic component, and the wiring board. The lead frame includes a first surface bonded to the electronic component and a second surface located opposite to the first surface and exposed from the sealing resin. The wiring board includes an insulating base material, a wiring layer formed on a first surface of the insulating base material, and an adhesive layer laminated on a second surface of the insulating base material on an opposite side of the first surface and including a second surface to which the electronic component is bonded. The first surface of the insulating base material and the second surface of the adhesive layer are covered by the sealing resin.