Flexible Substrate Bonding for Non-Coplanar LED Dies
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The high cost and complexity of LED-based lighting systems due to the need for high-power LEDs, thermal-management systems, and the use of stud bumps for bonding, which lead to increased costs, reduced efficiency, and reliability issues, especially with non-coplanar semiconductor die contacts.
Innovation Solution
A flexible and/or deformable substrate is used to bond semiconductor dies directly to electrical traces without stud bumps, utilizing a pressure-sensitive adhesive to form a mechanically strong and electrically conductive connection, allowing for non-coplanar contacts to be reliably connected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high-power LEDs are used to reduce package count, then light intensity is improved, but thermal management cost and complexity increase
Solution Approach 1:
The patent extracts the thermal management function from a separate complex system and integrates it directly into the substrate material itself. The substrate is designed with inherent thermal conductivity properties, eliminating the need for separate thermal slugs, ceramic submounts, and heat sink structures. This extraction simplifies the overall device while maintaining high-power LED performance.
Solution Approach 2:
The substrate is designed to perform multiple functions simultaneously: mechanical support, electrical connection, and thermal management. By making the substrate multi-functional, the patent eliminates the need for separate dedicated thermal management components, reducing overall device complexity while supporting high-power LED operation.
2Strength
If stud bumps are used for bonding semiconductor dies, then mechanical strength is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent removes the stud bump intermediate structure from the bonding process. Instead of using stud bumps as a separate bonding intermediary, the substrate directly bonds to the semiconductor die contacts through conventional adhesive bonding, eliminating the need for stud bump fabrication and attachment steps.
Solution Approach 2:
Instead of building up structure with stud bumps to achieve bonding, the patent inverts the approach by using a planar substrate surface that bonds directly to the die. This inversion simplifies the bonding process while achieving equivalent or superior bonding strength through direct adhesive bonding between the substrate and die contacts.
3Stability of the object's composition
If rigid substrates are used for LED mounting, then structural stability is improved, but adaptability to non-coplanar contacts is reduced
Solution Approach 1:
The patent introduces dynamic compliance to the substrate through a multi-layer construction that includes a rigid support layer and a compliant bonding layer. This allows the substrate to adapt its shape during bonding to match non-coplanar die contacts, while maintaining structural stability during operation. The compliant layer acts as a buffer that absorbs misalignment.
Solution Approach 2:
The substrate is constructed as a composite material system combining rigid and compliant layers. The rigid layer provides structural stability and thermal management, while the compliant layer provides adaptability for bonding to non-coplanar contacts. This composite structure resolves the contradiction between stability and adaptability.
4Power
If larger contact areas are used to support high current, then current capacity is improved, but light-emitting area is reduced
Solution Approach 1:
The patent moves the current distribution function to another dimension by using a three-dimensional conductive structure within the substrate. Instead of increasing contact area on the two-dimensional surface, the substrate provides vertical current pathways through conductive layers and traces, allowing small surface contacts to support high current through volumetric current 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
This approach simplifies bonding procedures, reduces costs, and enhances the reliability and efficiency of LED-based lighting systems by eliminating the need for expensive thermal-management systems and stud bumps, while enabling the use of LED lighting in applications previously unsuitable for rigid substrates.
Implementation Method 1
utilizing a pressure-sensitive adhesive to form a mechanically strong and electrically conductive connection
Implementation Method 2
A flexible and/or deformable substrate is used to bond semiconductor dies directly to electrical traces without stud bumps
Data Source
AI summary
In accordance with certain embodiments, a light-emitting element composed of one or more discrete units configured for light emission is adhered directly to a yielding substrate with a pressure-activated adhesive notwithstanding any nonplanarity of the surface of the light-emitting element or non-coplanarity of the semiconductor die contacts.