Opto-Electric Hybrid Board Bonding for High-Temperature Reliability
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Solution Overview
Problem
In optical element-including opto-electric hybrid boards, high temperatures generated by the optical element can lead to a decrease in the mechanical strength and electrical connection reliability of the underfill resin and its vicinity.
Innovation Solution
The use of a bonding member with a thermal expansion coefficient of 80 ppm or less, combined with specific viscosity, tensile elastic modulus, and glass transition temperature ranges, helps to maintain mechanical strength and electrical connection reliability at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional underfill resin is used to bond the optical element to the electric circuit board, then the bonding function is achieved, but the mechanical strength decreases at high temperatures due to heat generation
Solution Approach 1:
The patent changes the thermal expansion coefficient parameter of the bonding member to 80 ppm or less, which is significantly lower than conventional underfill resins. This parameter change enables the bonding member to maintain its mechanical strength at high temperatures while still providing effective bonding between the optical element and electric circuit board, thereby resolving the contradiction between reliability and strength.
Solution Approach 2:
The patent employs a composite material structure where the bonding member is formulated with specific composition (including silane-modified epoxy resin, filler particles, and coupling agents) to achieve both low thermal expansion coefficient and high mechanical strength. This composite approach allows the material to simultaneously provide thermal stability and structural integrity under high temperature conditions.
2Strength
If the thermal expansion coefficient of the bonding member is reduced to maintain mechanical strength at high temperature, then strength is improved, but stress concentration may increase
Solution Approach 1:
The patent optimizes the thermal expansion coefficient to a specific range (80 ppm or less, preferably 50 ppm or less, more preferably 30 ppm or less) that balances stress reduction with mechanical strength maintenance. This precise parameter control ensures the bonding member can accommodate thermal expansion differences between components while maintaining sufficient strength, thereby resolving the contradiction between strength and stress.
3Ease of manufacture
If the viscosity of the bonding material is reduced for easy pouring, then ease of manufacture is improved, but mechanical strength may decrease
Solution Approach 1:
The patent specifies the viscosity of the bonding material at 25°C to be within a precise range of 0.1 Pa·s to 10 Pa·s. This parameter optimization ensures the material has sufficient flowability for complete filling of the gap between components during manufacturing, while the specific viscosity range also ensures proper wetting and bonding strength after curing, thereby resolving the contradiction between ease of manufacture and mechanical strength.
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 solution effectively suppresses the decrease in mechanical strength and electrical connection reliability of the bonding member and the optical element-electric circuit board interface at high temperatures, ensuring reliable performance.
Implementation Method 1
a thermal expansion coefficient of the bonding member is 80 ppm or less... since the thermal expansion coefficient of the bonding member is 80 ppm or less, it is possible to suppress a decrease in the mechanical strength of the bonding member at a high temperature based on the heat generation of the optical element
Data Source
AI summary
An optical element-including opto-electric hybrid board includes an opto-electric hybrid board including an optical waveguide and an electric circuit board in order toward one side in a thickness direction, an optical element mounted on the electric circuit board at one side in the thickness direction of the opto-electric hybrid board, and a bonding member interposed between the optical element and the electric circuit board so as to bond the optical element to the electric circuit board. A thermal expansion coefficient of the bonding member is 80 ppm or less.