Miniature Surface Mount LED Package Thermal Management
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Solution Overview
Problem
Existing surface mount devices (SMDs) for LED displays face challenges in maintaining low operating temperatures, reducing size, and increasing viewing angles while dealing with heat dissipation and glare issues, which affect color fidelity and reliability.
Innovation Solution
A surface mount LED package design featuring a lead frame with a conductive chip carrier and a polymer casing that includes a cavity for increased heat dissipation, with a common conductive chip carrier and a plastic casing that encases the lead frame, allowing for efficient heat spreading and reduced glare.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling strategies including conduction heat transfer along leads are used, then heat dissipation is achieved, but the leads do not have sufficient mass or exposed surface area to provide effective heat dissipation for high intensity LEDs
Solution Approach 1:
The device is segmented into distinct functional zones: a first cavity for LED mounting with its own heat dissipation structure, and a second cavity for driver circuitry with separate thermal management. This allows targeted cooling strategies for each component type, optimizing heat dissipation efficiency.
Solution Approach 2:
The invention transitions from one-dimensional lead-based heat conduction to multi-dimensional heat dissipation by incorporating a heat sink structure with extended surfaces in the first cavity, increasing the effective heat transfer area in multiple spatial dimensions.
2Volume of moving object
If the SMD package size is reduced to achieve compact displays, then pixel pitch is decreased, but thermal management becomes more challenging due to reduced space for heat dissipation structures
Solution Approach 1:
The driver circuitry is nested within the second cavity of the same SMD package, allowing the LED array and driver to be integrated in a single compact unit. This nesting approach minimizes overall package size while maintaining functional separation for thermal management.
Solution Approach 2:
The patent applies different structural qualities to different regions: the first cavity contains a heat sink with extended surfaces for active heat dissipation, while the second cavity provides a compact enclosure for low-power driver circuitry, optimizing each zone's thermal characteristics.
3Ease of manufacture
If material with reflective characteristics is used for LED package or mounting, then manufacturing is simplified, but color fidelity decreases due to unwanted light reflection and glare
Solution Approach 1:
The cavity structures are designed with specific geometric qualities that control light behavior locally. The first cavity's shape and the heat sink's surface geometry are optimized to minimize unwanted reflections while maintaining manufacturing feasibility, applying different optical qualities to different surfaces.
4Adaptability or versatility
If viewing angle is increased to improve display visibility, then off-axis viewing is enhanced, but color fidelity is lost with increasing viewing angle
Solution Approach 1:
The cavity geometry is specifically designed to control light emission characteristics in different directions. The shape and surface properties of the first cavity create localized optical zones that maintain color fidelity while allowing broader viewing angles through controlled light distribution.
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
The design achieves effective thermal management, improved color fidelity across various viewing angles, and a compact size, reducing manufacturing costs while maintaining the reliability of LED displays.
Implementation Method 1
One conventional way of implementing conduction heat transfer for dissipating heat in an electronic package is to allow the heat to conduct away along the leads of the device
Implementation Method 2
the material of each LED package and/or the material used to mount each of the LEDs may have reflective characteristics, which can further decrease color fidelity by creating unwanted light reflection and/or glare
Data Source
AI summary
A surface mount LED package includes a lead frame carrying a plurality of LEDs and a plastic casing at least partially encasing the lead frame. The lead frame includes an electrically conductive chip carrier and first, second, and third electrically conductive connection parts separate from the electrically conductive chip carrier. Each of the first, second and third electrically conductive connection parts has an upper surface, a lower surface, and a connection pad on the upper surface. The plurality of LEDs are disposed on an upper surface of the electrically conductive chip carrier. Each LED has a first electrical terminal electrically coupled to the electrically conductive chip carrier. Each LED has a second electrical terminal electrically coupled to the connection pad of a corresponding one of the first, second, and third electrically conductive connection parts.