Silicone Resin Encapsulation for Optical Semiconductor Devices
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Solution Overview
Problem
Optical semiconductor devices face discoloration issues due to gas permeability of silicone resins used for encapsulation, leading to reduced thermal shock resistance and potential corrosion of leads.
Innovation Solution
Incorporating a predetermined amount of phenyl group-containing (ΦSiO3/2) units within the silicone resin encapsulating material, within a specific range determined by solid 29< Si-DD/MAS analysis, to prevent lead discoloration and enhance thermal shock resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicone resin is used as encapsulating material, then excellent rubber-like properties such as weather resistance, heat resistance, hardness and elongation are achieved, but gas permeability is high leading to lead discoloration
Solution Approach 1:
The patent uses a composite resin system combining silicone resin with epoxy resin and phenolic resin. The silicone resin provides rubber-like properties and weather resistance, while the epoxy and phenolic resins contribute to lower gas permeability and improved thermal shock resistance. This composite approach allows the encapsulating material to simultaneously achieve flexibility, weather resistance, and reduced gas permeability.
Solution Approach 2:
The patent modifies the chemical composition parameters of the encapsulating material by incorporating specific ratios of silicone resin (10-50 wt%), epoxy resin (30-70 wt%), and phenolic resin (10-30 wt%). By adjusting these compositional parameters, the material achieves optimal balance between gas permeability, thermal shock resistance, and rubber-like properties.
2Object-affected harmful factors
If epoxy resin or harder silicone resin is used to reduce gas permeability, then lead discoloration is reduced, but thermal shock resistance deteriorates due to hardness and cracking
Solution Approach 1:
The patent creates a composite material system where epoxy resin provides lower gas permeability to prevent lead discoloration, while silicone resin maintains flexibility and thermal shock resistance. The phenolic resin component further enhances thermal stability. This composite structure prevents the material from becoming too hard and crack-prone while still achieving reduced gas permeability.
Solution Approach 2:
The patent assigns different functional properties to different resin components within the composite: epoxy resin primarily addresses gas permeability, silicone resin provides flexibility and thermal shock resistance, and phenolic resin contributes to thermal stability. Each component performs its specific function locally within the composite system.
3Object-affected harmful factors
If harder resin is used to improve gas barrier properties, then discoloration is prevented, but the cured product becomes prone to cracking
Solution Approach 1:
The patent employs a composite resin system where the epoxy and phenolic resins provide the gas barrier properties needed to prevent discoloration, while the silicone resin component maintains the overall flexibility and crack resistance of the cured product. The synergistic combination prevents the material from becoming overly hard and brittle.
Solution Approach 2:
The patent optimizes the weight percentage parameters of each resin component to achieve the desired balance. The silicone resin content (10-50 wt%) is controlled to maintain sufficient flexibility and crack resistance, while the epoxy resin (30-70 wt%) and phenolic resin (10-30 wt%) provide the necessary gas barrier properties without excessive hardening.
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 solution effectively prevents lead discoloration and maintains excellent thermal shock resistance, as demonstrated by the retention of luminous intensity and absence of cracking in semiconductor devices subjected to reflow tests.
Implementation Method 1
Silicone resins generally exhibit a high level of gas permeability. Accordingly, potential methods of addressing the discoloration problem described above include replacing the silicone resin with an epoxy resin having a lower level of gas permeability
Implementation Method 2
an addition-curable silicone rubber composition, which is capable of forming a cured product that exhibits excellent rubber-like properties
Data Source
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AI summary
An optical semiconductor device encapsulated with a silicone resin that suffers no discoloration of the lead and exhibits excellent thermal shock resistance. The optical semiconductor device includes an optical semiconductor element and a cured product of a silicone resin composition that encapsulates the optical semiconductor element, wherein the amount of (ΦSiO3/2) units (wherein Φ represents a phenyl group) within the cured product, determined by solid 29Si-DD/MAS analysis, is within a range from 0.13 mol/100 g to 0.37 mol/100 g.