Surface Mountable LED with Flip-Chip Metallurgical Bonding
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Solution Overview
Problem
Conventional LED light sources face issues with limited light output, spectral band limitations, and connection problems such as wire bond fragility, encapsulant aging, and increased costs due to precise placement requirements for flip-chip LEDs, which affect efficiency and reliability.
Innovation Solution
A surface mountable light-emitting device configuration featuring a light-emitting section and a base section, where the light-emitting section includes an active layer sandwiched between semiconductor layers, and the base section provides electrical connections and structural support with metal traces and insulating layers to minimize light absorption and enhance current distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonds are used to connect LED dies to substrate, then electrical connections can be established, but the wire bonds are fragile and require encapsulation protection which increases device complexity and cost
Solution Approach 1:
The patent extracts the problematic wire bonds and encapsulation from the system by adopting a flip-chip configuration where LED dies are directly mounted to the substrate with metallurgical bonds, eliminating the need for fragile wire bonds and their protective encapsulation
Solution Approach 2:
The patent replaces the mechanical wire bond system with a metallurgical bonding system where metal pads on the LED die are directly bonded to metal traces on the substrate through diffusion bonding, creating a more reliable and simpler structure
2Reliability
If encapsulant is used to protect wire bonds, then protection is provided, but the encapsulant absorbs light over time and stresses the wire bonds causing premature failure
Solution Approach 1:
The patent removes the encapsulant from the system by eliminating the wire bonds that required protection, thereby eliminating the source of light absorption and stress-related failures
Solution Approach 2:
The patent converts the harmful effect of needing encapsulation into a benefit by redesigning the connection method to eliminate the need for encapsulation entirely, thus avoiding light absorption and stress issues
3Reliability
If wire bonds are used for LED connections, then electrical connectivity is achieved, but the wire bonds block part of the emitted light reducing source efficiency
Solution Approach 1:
The patent extracts the light-blocking wire bonds from the optical path by using direct flip-chip mounting where electrical connections are made through the substrate plane rather than through space, eliminating light blocking
Solution Approach 2:
The patent moves the electrical connection from a three-dimensional wire bond through space into the two-dimensional substrate plane, allowing light to travel unobstructed while maintaining electrical connectivity
4Reliability
If flip-chip LEDs are used to avoid wire bond problems, then connection reliability improves, but precise placement requirements increase manufacturing complexity and cost
Solution Approach 1:
The patent applies preliminary action by pre-aligning and pre-bonding multiple LED dies to the substrate in an array configuration before final assembly, allowing for easier handling and reduced placement precision requirements during manufacturing
5Power
If multiple LED dies are combined into a single light-emitting element, then light output increases, but the device size increases reducing LED density
Solution Approach 1:
The patent merges multiple LED dies onto a single substrate to create a multi-LED device that provides high light output while maintaining a compact form factor suitable for surface mounting
Solution Approach 2:
The substrate serves multiple functions including electrical interconnection, mechanical support, and heat dissipation, allowing multiple LED dies to be combined without proportionally increasing device area
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 enhances light output, reduces device size, and improves reliability by minimizing light absorption and current non-uniformity, while allowing for more efficient and cost-effective manufacturing with reduced risk of shorts and increased LED density.
Implementation Method 1
The bottom layer includes an insulating layer bonded to a surface thereof, and the second conductor includes a layer of metal bonded to the insulating layer, the insulating layer preventing contact between the second conductor and the bottom layer
Implementation Method 2
The bottom contact is connected to the first bottom electrode by a first conductor and the second bottom electrode is connected to the top contact by a second conductor
Implementation Method 3
The top base surface is bonded to the bottom layer
Data Source
AI summary
A surface mountable device having a circuit device and a base section. The circuit device includes top and bottom layers having a top contact and a bottom contact, respectively. The base section includes a substrate having a top base surface and a bottom base surface. The top base surface includes a top electrode bonded to the bottom contact, and the bottom base surface includes first and second bottom electrodes that are electrically isolated from one another. The top electrode is connected to the first bottom electrode, and the second bottom electrode is connected to the top contact by a vertical conductor. An insulating layer is bonded to a surface of the circuit device and covers a portion of a vertical surface of the bottom layer. The vertical conductor includes a layer of metal bonded to the insulating layer.