Interlayer Wiring Board Structure for Thermal Shock Resistance
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Solution Overview
Problem
Wiring boards experience significant fluctuations in resistance values due to repeated thermal shocks between low and high temperatures, which existing technologies fail to adequately address.
Innovation Solution
The wiring boards are designed with insulating layers and interlayer connection conductors where the thermal expansion coefficient of the insulating layer is greater than that of the interlayer connection conductor, and the storage elastic modulus of the insulating layer is higher than that of the interlayer connection conductor, maintaining stable electrical connections under thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the elastic modulus of the resin mixture is reduced to below 2 GPa at 85°C to improve connection stability in high-temperature high-humidity environments, then the resistance fluctuation is reduced, but the resistance value still fluctuates significantly when repeated thermal shocks are applied between -40°C and 85°C
Solution Approach 1:
The invention changes the key parameters from solely elastic modulus to a combination of thermal expansion coefficient and elastic modulus. By controlling the thermal expansion coefficient to be 15×10^-6/K to 30×10^-6/K and the elastic modulus to be 0.5 GPa to 2.0 GPa at 85°C, the interlayer connection conductor achieves coordinated thermal expansion with the insulating layer, preventing resistance fluctuation under repeated thermal shocks while maintaining connection stability in high-temperature high-humidity environments
Solution Approach 2:
The invention uses a composite material system consisting of conductive particles embedded in a resin matrix. The resin mixture contains epoxy resin (30-90 wt%), silicone resin (10-60 wt%), and other components, creating a composite that combines the low elastic modulus of silicone with the thermal stability of epoxy, achieving both thermal shock resistance and connection stability
2Stability of the object's composition
If the thermal expansion coefficient of the interlayer connection conductor is increased to match the insulating layer, then thermal stress is reduced, but the connection strength may be compromised
Solution Approach 1:
The invention optimizes the thermal expansion coefficient parameter to a specific range (15×10^-6/K to 30×10^-6/K) that balances thermal expansion compatibility with connection strength. This parameter control ensures the interlayer connection conductor expands and contracts at the same rate as the insulating layer during thermal cycles, preventing stress concentration while maintaining mechanical bond integrity
Solution Approach 2:
The invention applies different material compositions to different regions of the interlayer connection conductor. The conductive paste contains conductive particles (30-75 vol%) embedded in a resin matrix with specific local properties, creating a material that has both the required thermal expansion characteristics and sufficient mechanical strength for reliable connections
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 reduces or prevents resistance value fluctuations even in environments with repeated thermal shocks, ensuring reliable electrical connectivity across varying temperatures.
Implementation Method 1
When a thermal expansion coefficient of the insulating layer in the lamination direction is defined as ∝z10, a thermal expansion coefficient of the interlayer connection conductor in the lamination direction is defined as ∝z30... relationships of ∝z10>∝z30 are satisfied
Implementation Method 2
a storage elastic modulus of the insulating layer is defined as E′10, and a storage elastic modulus of the interlayer connection conductor is defined as E′30... relationships of E′10>E′30 are satisfied
Data Source
AI summary
A wiring board includes an insulating layer, a conductive layer on the insulating layer, and an interlayer connection conductor extending through the insulating layer in a lamination direction. The interlayer connection conductor is connected to the conductive layer. When a thermal expansion coefficient of the insulating layer in the lamination direction is defined as ∝z10, a thermal expansion coefficient of the interlayer connection conductor in the lamination direction is defined as ∝z30, a storage elastic modulus of the insulating layer is defined as E′10, and a storage elastic modulus of the interlayer connection conductor is defined as E′30, relationships of ∝z10>∝z30 and E′10>E′30 are satisfied in a temperature range from about −40° C. to about 85° C.