Optical Semiconductor Mounting Package With Gap-Free Resin-Electrode Joint
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Solution Overview
Problem
Optical semiconductor devices face reliability issues due to gaps between thermosetting resin moldings and lead electrodes, caused by coefficient mismatch and stress, leading to adhesion decrease, resin flash formation, and potential cracking, especially under harsh conditions and with ultraviolet light emission.
Innovation Solution
An optical semiconductor element mounting package with a recessed part formed by integrating a thermosetting light-reflecting resin composition and lead electrodes, featuring a filler composition with epoxy resin, curing agents, inorganic fillers, and white pigments, which provides high optical reflectivity and improved adhesion through transfer molding, reducing gaps and enhancing thermal and light resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermosetting resin composition is used to form the resin molding, then the resin molding provides good electrical insulation and structural support, but gaps form at the joint face between the resin molding and lead electrodes due to coefficient mismatch and stress
Solution Approach 1:
A metal film is introduced as an intermediary layer between the lead electrode and the thermosetting resin molding. This metal film serves as a mediator that improves adhesion between the two materials by providing a bonding surface that is compatible with both the metal electrode and the resin, thereby preventing gap formation while maintaining electrical insulation and structural support functions.
Solution Approach 2:
The joint structure is designed as a composite material system consisting of the lead electrode, metal film, and thermosetting resin molding layers. This composite structure combines the advantages of each material: the conductivity and mechanical strength of metal, the adhesive properties of the metal film, and the electrical insulation and structural support of the resin molding, thereby achieving both strong adhesion and high reliability.
2Ease of manufacture
If the resin molding and lead electrodes are integrated by conventional molding methods, then manufacturing is simplified, but resin flash forms at the joint face and cracking may occur under harsh conditions
Solution Approach 1:
The metal film is formed on the lead electrode surface before the resin molding process. This preliminary action prepares the bonding surface in advance, ensuring that when the thermosetting resin is injected and cured, it adheres properly to the metal film without forming gaps or resin flash, thereby achieving high joint face precision while maintaining ease of manufacture.
Solution Approach 2:
The molding process parameters are optimized to control the injection pressure, temperature, and curing conditions of the thermosetting resin. By adjusting these parameters, the resin fills the mold cavity completely without excessive pressure that would cause flash, while ensuring proper adhesion to the metal film and preventing cracking under subsequent harsh conditions.
3Ease of manufacture
If conventional resin compositions are used, then manufacturing cost is reduced, but optical reflectivity and resistance to ultraviolet light degradation are insufficient
Solution Approach 1:
The thermosetting resin composition is formulated as a composite material containing inorganic fillers (such as titanium dioxide, zinc oxide, or barium sulfate) and white pigments dispersed in the resin matrix. This composite structure provides both the structural and electrical insulation functions of the resin and high optical reflectivity across the visible and ultraviolet spectra, while the inorganic fillers also provide resistance to UV light degradation.
Solution Approach 2:
The resin molding is designed with different local properties: the bulk resin provides structural support and electrical insulation, while the distributed inorganic fillers and white pigments localized throughout the resin matrix provide enhanced optical reflectivity and UV resistance. This local quality approach allows the resin to perform multiple functions simultaneously without significantly increasing manufacturing cost.
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 ensures good adhesion between resin molding and lead electrodes, maintaining device reliability and reflectivity from visible to near-ultraviolet light, while preventing cracking and moisture ingress, thus enhancing the overall performance and longevity of optical semiconductor devices.
Implementation Method 1
a resin molding composed of a thermosetting light-reflecting resin composition
Implementation Method 2
thermosetting light-reflecting resin composition
Data Source
AI summary
An optical semiconductor element mounting package as well as an optical semiconductor device using the package are provided. The optical semiconductor element mounting package has a recessed part that serves as an optical semiconductor element mounting region. The package includes a resin molding and at least a pair of positive and negative lead electrodes. The resin molding is composed of a thermosetting light-reflecting resin composition, which forms at least the side faces of the recessed part. The lead electrodes are disposed opposite to each other so as to form part of the bottom face of the recessed part, and there is no gap at a joint face between the resin molding and the lead electrodes.