Gel-Like Silicone Buffer for Optical Coupling Thermal Stress
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Solution Overview
Problem
In optical coupling devices, the strong adhesion between resins with different thermal expansion coefficients can lead to peeling of the light emitting chip from the light receiving chip due to thermal stress, causing a deterioration in optical coupling characteristics.
Innovation Solution
The use of a gel-like silicone with a hardness value between 16 to 24, which acts as a tension relaxing member, covers the light emitting chip, and a resin portion with a higher hardness covers the silicone, creating a flexible interface that prevents peeling by accommodating thermal expansion differences without the need for plasma cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a second resin is strongly adhered to the first resin, then adhesion strength is improved, but the light emitting chip may peel from the light receiving chip due to thermal expansion stress
Solution Approach 1:
A gel-like silicone layer is introduced as an intermediary between the first resin and the second resin. This intermediate layer has a hardness of 16-24 and serves as a buffer that absorbs thermal expansion stress, preventing it from being transmitted to the light emitting chip while still maintaining overall structural adhesion.
Solution Approach 2:
The hardness parameter of the intermediate layer is specifically controlled to be between 16-24. This parameter optimization allows the material to be soft enough to absorb thermal stress but firm enough to maintain adhesion, resolving the contradiction between strong bonding and stress absorption.
2Strength
If plasma cleaning is performed to improve adhesion, then adhesion strength is improved, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of using expensive and complex plasma cleaning processes, the invention employs a simple gel-like silicone material that inherently provides good adhesion without requiring additional surface treatment steps. This simpler, more economical approach achieves the same adhesion goal without the complexity of plasma equipment and processes.
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 effectively prevents peeling of the light emitting chip during temperature and humidity variations, maintaining stable optical coupling efficiency and simplifying the manufacturing process by eliminating the need for plasma cleaning.
Implementation Method 1
since the first resin and the second resin generally have different thermal expansion coefficients, a strong adhesion between the first resin and the second resin leads to a concern that the light emitting chip will peeled from the light receiving chip due to force applied from the second resin portion
Data Source
AI summary
According to one embodiment, a semiconductor device includes a first semiconductor element having a first surface, a second semiconductor element having a lower surface bonded to the first surface of the first semiconductor element, a gel-like silicone that covers an upper surface of the second semiconductor element, and a resin portion that covers the gel-like silicone and the first surface of the first semiconductor element.