LED Resin Package Molding for Gap-Free Electrode Adhesion
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Solution Overview
Problem
Optical semiconductor devices face reliability issues due to stress from mismatched coefficients of linear expansion between thermosetting resin compositions and copper lead electrodes, leading to adhesion decreases and potential gaps, which can result in reduced reliability and appearance defects, especially under harsh conditions and when exposed to ultraviolet light.
Innovation Solution
An optical semiconductor element mounting package with a recessed part formed by integrating a thermosetting light-reflecting resin composition and lead electrodes, where the resin composition includes epoxy, a curing agent, inorganic filler, white pigment, and coupling agent, providing high reflectivity and thermal stability, and is manufactured using transfer molding to ensure no gaps between the resin molding and lead electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermosetting resin composition is used to integrate lead electrodes and resin molding, then manufacturing process is simplified, but adhesion decreases and gaps form due to coefficient of linear expansion mismatch
Solution Approach 1:
The patent changes the chemical composition parameters of the resin composition by adding specific adhesion promoters (silane coupling agents) and adjusting the ratio of thermosetting resin to filler materials. This modifies the curing characteristics and thermal expansion properties to better match the lead electrodes, reducing gap formation while maintaining manufacturing simplicity
Solution Approach 2:
The patent creates a composite resin material combining thermosetting resin with inorganic fillers (alumina, silica) and adhesion promoters. This composite structure provides both the structural integrity needed for integration and the adhesion properties required to prevent gaps, resolving the contradiction between ease of manufacture and reliability
2Illumination intensity
If white pigment is added to resin molding for high reflectivity, then optical performance improves, but manufacturing complexity increases
Solution Approach 1:
The patent merges multiple functions into the resin composition itself: the white pigment (titanium dioxide, barium sulfate) provides reflectivity, while the same resin matrix provides structural support and adhesion. This integration eliminates separate optical coating steps, improving reflectivity without significantly increasing manufacturing complexity
Solution Approach 2:
The patent applies white pigment specifically in the resin molding regions requiring high reflectivity (side walls and bottom of recessed part), while using different material compositions in other areas. This localized approach optimizes optical performance where needed without unnecessarily complicating the entire device structure
3Object-affected harmful factors
If lead electrodes are fully covered by resin molding for protection, then environmental resistance improves, but heat dissipation decreases
Solution Approach 1:
The patent applies resin molding selectively to cover only the portions of lead electrodes that require environmental protection (side walls and non-heat-dissipation areas), while leaving the main heat dissipation surfaces exposed. This localized protection approach maintains environmental resistance without compromising thermal management
Solution Approach 2:
The patent segments the resin molding coverage into functional zones: protective coverage on lateral surfaces and selective exposure of heat dissipation surfaces. This segmentation allows simultaneous achievement of environmental protection and thermal management by assigning different functions to different regions of the lead electrode structure
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 achieves good adhesion and reliability between the resin molding and lead electrodes, maintains high reflectivity for visible and ultraviolet light, and provides thermal and light resistance, enhancing the overall performance and durability of the optical semiconductor device.
Implementation Method 1
a thermosetting light-reflecting resin composition... provides high reflectivity
Implementation Method 2
the resin composition includes... coupling agent... achieves good adhesion between the resin molding and lead electrodes
Data Source
AI summary
A method of manufacturing a light emitting device includes disposing at least one light emitting element on a recessed part of a resin package. The resin package having the recessed part includes a resin molding with a white pigment having a particle size from 0.1 μm to 50 μm and at least one lead electrode. The resin molding is disposed on a portion of a main face of the at least one lead electrode and is not in contact with a rear face of the at least one lead electrode. There is no gap at a joint face between the resin molding and the at least one lead electrode. The at least one light emitting element is disposed on the main face of the at least one lead electrode.