Multilayer Wiring Base Plate Thermal Stress Mitigation
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Solution Overview
Problem
Thin-film resistors in multilayer wiring base plates for probe cards experience deterioration and breakage due to heat expansion and contraction differences with surrounding synthetic resin layers, leading to reduced durability under temperature shock conditions.
Innovation Solution
Incorporating a heat expansion and contraction restricting layer with a smaller linear expansion coefficient than the synthetic resin layers, buried adjacent to the thin-film resistor, to mitigate stress caused by temperature changes, and using connection electrodes to disperse stress at the interface, while being electrically insulated from the wiring circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a thin-film resistor is buried in a synthetic resin layer to form a multilayer wiring base plate, then the resistor can be integrated into the wiring circuit, but the resistor experiences repeated stresses and deterioration under heat cycle test conditions due to linear expansion coefficient differences between the resistor and the resin layer
Solution Approach 1:
A heat expansion and contraction restricting layer is introduced as an intermediary between the thin-film resistor and the synthetic resin layer. This restricting layer has a linear expansion coefficient that is closer to that of the synthetic resin layer, thereby mediating the thermal expansion mismatch and reducing the repeated stresses on the thin-film resistor during heat cycle testing.
Solution Approach 2:
The heat expansion and contraction restricting layer is specifically positioned adjacent to the thin-film resistor in the synthetic resin layer. This local placement ensures that the stress mitigation effect is concentrated at the critical interface between the resistor and the resin layer, rather than uniformly throughout the entire structure.
2Reliability
If the linear expansion coefficient of the synthetic resin layer is reduced to match the thin-film resistor, then stress reduction is achieved, but the manufacturing flexibility and material selection are limited
Solution Approach 1:
The structure is segmented into distinct functional layers: the synthetic resin layer provides mechanical support and electrical insulation, while the separate heat expansion and contraction restricting layer provides thermal mismatch management. This segmentation allows each layer to be optimized independently for its specific function without compromising the other.
Solution Approach 2:
The multilayer wiring base plate employs a composite structure combining the synthetic resin layer with the heat expansion and contraction restricting layer. This composite approach leverages the advantages of both materials - the resin layer's mechanical properties and the restricting layer's thermal expansion characteristics - to achieve both structural integrity and stress reduction.
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
Enhances the durability of the thin-film resistor and the multilayer wiring base plate by reducing stress from heat expansion and contraction differences, thereby improving the overall durability of the probe card under heat cycle test conditions.
Implementation Method 1
having a smaller linear expansion coefficient than a linear expansion coefficient of the adjacent synthetic resin layers
Data Source
AI summary
A multilayer wiring base plate includes an insulating plate including a plurality of synthetic resin layers made of an insulating material, a wiring circuit provided in the insulating plate, a thin-film resistor formed along at least one of the synthetic resin layers to be buried in the synthetic resin layer and inserted in the wiring circuit, and a heat expansion and contraction restricting layer formed to be buried in the synthetic resin layer adjacent to the synthetic resin layer in which the thin-film resistor is formed to be buried, arranged along the thin-film resistor, and having a smaller linear expansion coefficient than a linear expansion coefficient of the adjacent synthetic resin layers.