LED Submount Contact Pad Layout for Stress-Balanced Bonding
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Solution Overview
Problem
Challenges exist in producing high-quality light-emitting diodes (LEDs) with desired emission characteristics while providing suitable mechanical support and electrical connections, particularly in mitigating stress-related deformation of active LED structures after growth substrate removal.
Innovation Solution
The use of contact structures for submounts with differing heights and shapes for anode and cathode mounting pads, along with additional support layers, to improve bonding integrity and mitigate stress-related deformation in LED chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mounting pads are made with uniform height and shape, then manufacturing is simplified, but bonding integrity and stress distribution are compromised
Solution Approach 1:
The patent applies asymmetry by making the first mounting pad (anode pad) taller than the second mounting pad (cathode pad). This asymmetric height design ensures that the taller first mounting pad provides sufficient bonding surface area and mechanical support for the corresponding first contact, while the shorter second mounting pad is adequate for the second contact. This resolves the contradiction by sacrificing manufacturing uniformity to achieve superior bonding integrity and stress distribution.
2Device complexity
If growth substrate is removed to reduce device complexity, then mechanical support is improved, but stress-related deformation increases
Solution Approach 1:
The patent applies preliminary anti-action by designing the asymmetric mounting pad structure in advance to counterbalance the stress that will arise after growth substrate removal. The taller first mounting pad and shorter second mounting pad are configured to create opposing stress forces that neutralize each other, preventing deformation. This allows the growth substrate to be removed for simplified structure while pre-computed pad asymmetry prevents the harmful stress-related deformation that would otherwise occur.
3Manufacturing precision
If mounting pad heights are equal, then manufacturing precision requirements are reduced, but stress counterbalance capability is lost
Solution Approach 1:
The patent deliberately introduces asymmetric heights between the first and second mounting pads to create stress counterbalance capability. The first mounting pad extends to a first height while the second mounting pad extends to a second height that is less than the first height. This asymmetry is designed to generate opposing stress forces that counterbalance each other, providing superior stress resistance. The manufacturing precision requirements are increased to accommodate this deliberate asymmetry, but the trade-off achieves enhanced structural strength and deformation resistance.
Data Source
AI summary
Light-emitting devices and more particularly contact structures for submounts in light-emitting diode (LED) devices are disclosed. Exemplary devices include LED chips with active LED structures bonded to carrier submounts. Contact structures include arrangements of mounting pads of carrier submounts relative to contacts of active LED structures that improve bonding integrity and/or mitigate stress-related deformation in active LED structures where growth substrates are removed. Exemplary contact structures include differing heights between anode and cathode mounting pads, particularly greater heights for mounting pads with smaller surface areas to ensure suitable bonding contact. Additional contact structures include arrangements of contacts and corresponding mounting pads that position bonding interfaces about various areas of LED chips that mitigate and/or counterbalance certain areas prone to stress-related deformation.