Flexible Interconnect Structure for LED Arrays on Heatsinks
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Solution Overview
Problem
Existing methods for assembling light emitting semiconductor devices, such as LEDs, on insulated metal substrates face challenges with curved surfaces, limited form factor, and increased thermal resistance, which restrict their application in complex shapes and reduce efficiency.
Innovation Solution
A flexible interconnect structure using a dielectric film with metal interconnects that conforms to complex shapes, eliminating the need for traditional insulated metal substrates and wirebonds, allowing direct attachment of LEDs to a heatsink for improved thermal performance and multidirectional lighting capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional insulated metal substrates with dielectric layers are used, then electrical insulation is provided, but thermal resistance increases and thermal performance deteriorates
Solution Approach 1:
The patent removes the dielectric layer from between the LED chip and heatsink, extracting the thermal resistance element while maintaining electrical insulation through alternative means (metal interconnect structure design and overlay circuit configuration). This directly resolves the contradiction by eliminating the thermal barrier while preserving electrical isolation.
Solution Approach 2:
The metal interconnect structure serves as an intermediary that provides both thermal conduction pathways and electrical insulation when properly configured. The overlay circuit with conductive traces on a substrate acts as a mediator that maintains electrical isolation while allowing direct thermal contact between LED and heatsink.
2Reliability
If wirebonding is used to connect LED chips to IMS, then electrical connections are established, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges the electrical connection function and mechanical support function into a single integrated metal interconnect structure. The overlay circuit combines multiple conductive traces and connection points into one unified component that replaces multiple wirebonds, reducing assembly steps and structural complexity while maintaining reliable electrical connections.
Solution Approach 2:
The metal interconnect structure performs multiple functions simultaneously: it provides electrical connection, mechanical support, and thermal management interface. The overlay circuit serves as both a structural element and an electrical interconnection network, eliminating the need for separate wirebonding operations and reducing overall device complexity.
3Strength
If insulated metal substrates with fixed form factors are used, then structural support is provided, but adaptability to complex shapes is limited
Solution Approach 1:
The patent employs flexible or bendable substrate materials for the overlay circuit that can dynamically adapt to various heatsink geometries. The metal interconnect structure can be configured in different arrangements to match complex surfaces, providing structural support while maintaining adaptability to curved, angled, or irregular shapes unlike rigid traditional IMS.
Solution Approach 2:
The overlay circuit uses flexible substrate materials and thin-film metal traces that can conform to complex three-dimensional surfaces. This flexible construction maintains structural integrity and electrical connectivity while adapting to various heatsink profiles, enabling applications on curved or irregular surfaces that rigid IMS cannot accommodate.
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
Enables the arrangement of LEDs in various complex shapes with robust interconnects, reducing thermal resistance and enhancing lumen output by eliminating dielectric layers and wirebonds, thus improving thermal performance and lighting coverage.
Implementation Method 1
a metal interconnect structure formed on the flexible dielectric film, the metal interconnect structure extending through vias formed through the flexible dielectric film so as to be electrically connected to the connection pads of the LES chips
Implementation Method 2
an array of LES chips mounted on the heatsink and electrically connected thereto
Data Source
AI summary
A system and method for packaging light emitting semiconductors (LESs) is disclosed. An LES device (10) is provided that includes a heatsink (14) and an array of LES chips (12) mounted on the heatsink (14) and electrically connected thereto, with each LES chip comprising connection pads (28) and a light emitting area (32) configured to emit light therefrom responsive to a received electrical power. The LES device (10) also includes a flexible interconnect structure (18) positioned on and electrically connected to each LES chip to provide for controlled operation of the array of LES chips (12), with the flexible interconnect structure (18) further including a flexible dielectric film (24) configured to conform to a shape of the heatsink (14) and a metal interconnect structure (22) formed on the flexible dielectric film (24) and that extends through vias (26) formed in the flexible dielectric film (24) so as to be electrically connected to the connection pads (28) of the LES chips (12).