LED Lead Frame Structure for Heat Dissipation and Case Retention
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Solution Overview
Problem
Conventional semiconductor light-emitting devices face challenges in maintaining compact size while ensuring strong light emission and effective heat conduction, as increasing the width of the lead frame to enhance heat conduction weakens the frame-holding force, potentially causing the lead frame to detach from the case.
Innovation Solution
A semiconductor light-emitting device design featuring a lead frame with a bonding region and alternating thin and thick extensions, where the thin extensions are flush with the top surface and offset from the bottom surface, and the thick extensions are exposed outside the case, providing enhanced heat dissipation and secure attachment to the case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the width of the longer strip portion 91a is increased to enhance heat conduction, then heat dissipation performance is improved, but the frame-holding force of the case 93 is weakened, potentially causing the lead frame to detach
Solution Approach 1:
The lead frame structure is segmented into multiple functional portions: a bonding region for LED mounting, thin extensions for heat conduction, thick extensions for structural support, and protruding portions for case attachment. This segmentation allows each portion to be optimized for its specific function, resolving the contradiction between heat dissipation and frame-holding force.
Solution Approach 2:
Different portions of the lead frame are given different local qualities: the thin extensions have reduced thickness for heat conduction efficiency, while the thick extensions maintain original thickness for structural strength. The protruding portions are strategically positioned to provide localized attachment points, ensuring that heat dissipation and frame-holding functions are simultaneously optimized without compromising overall performance.
2Temperature
If the width of the lead frame is broadened to improve heat conduction, then thermal management is enhanced, but the overall device size increases, compromising compactness
Solution Approach 1:
The lead frame utilizes three-dimensional space efficiently by extending in multiple directions from the bonding region. The thin extensions broaden the heat conduction path in the lateral direction, while the protruding portions extend toward the case to provide attachment points. This multi-directional extension allows enhanced heat dissipation without proportionally increasing the overall device footprint, maintaining compactness while improving thermal management.
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 allows for efficient heat dissipation and secure attachment, maintaining the compact size while ensuring reliable light emission and preventing the lead frame from detaching, thus achieving bright and stable light emission.
Implementation Method 1
the amount of heat generated by the LED chip 92 is increased, and for maintaining the proper light emission, the heat should be conducted from the longer strip portion 91a to the circuit board
Implementation Method 2
the side walls of the case 93 need to be made thinner to permit the size increase of the longer strip portion 91a. This configuration, however, will weaken the frame-holding force of the case 93, which may allow the lead frame 91 to drop off from the case 93
Data Source
AI summary
A semiconductor light-emitting device includes a lead frame, a semiconductor light-emitting element mounted on the top surface of the bonding region, and a case covering part of the lead frame. The bottom surface of the bonding region is exposed to the outside of the case. The lead frame includes a thin extension extending from the bonding region and having a top surface which is flush with the top surface of the bonding region. The thin extension has a bottom surface which is offset from the bottom surface of the bonding region toward the top surface of the bonding region.