Resin Multilayer Substrate Inner Conductor Thermal Expansion
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Solution Overview
Problem
Resin multilayer substrates face peeling issues due to thermal expansion mismatch between resin base-material layers and side-surface conductors, leading to potential conductor detachment.
Innovation Solution
Incorporating inner conductors, such as dummy or ground conductors, between the side-surface conductor and circuit components, made of materials with a thermal expansion coefficient closer to the plane direction of the resin base-material layers, to reduce thermal expansion and prevent peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the coefficient of thermal expansion of the resin base-material layer in the thickness direction is higher than that of the side-surface conductor, then the resin base-material layer can accommodate thermal stress, but the side-surface conductor may peel from the side surface
Solution Approach 1:
The patent introduces inner conductors as intermediary elements positioned between the side-surface conductor and the resin base-material layers. These inner conductors serve as a thermal expansion mediator, with their coefficients of thermal expansion carefully selected to be between those of the side-surface conductor and the resin layers, thereby reducing thermal stress concentration and preventing peeling
Solution Approach 2:
The patent changes the thermal expansion parameters by selecting specific materials for the inner conductors. The coefficient of thermal expansion of the inner conductor material is controlled to satisfy: coefficient of side-surface conductor < coefficient of inner conductor < coefficient of resin base-material layer in thickness direction. This parameter adjustment creates a gradual transition in thermal expansion properties, reducing stress concentration
2Reliability
If inner conductors are added between the side-surface conductor and circuit component, then peeling is prevented, but device complexity increases
Solution Approach 1:
The inner conductors perform multiple functions simultaneously: they act as thermal expansion buffers to prevent peeling, serve as ground conductors or dummy conductors for electrical shielding, and provide structural support within the multilayer substrate. This multi-functionality reduces the need for separate components and justifies the added structural elements
Solution Approach 2:
The inner conductors are nested within the multilayer resin base-material structure, with each inner conductor embedded in its respective resin layer. This nesting approach integrates the stress-prevention function into the existing substrate architecture rather than adding external components, minimizing overall complexity
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 effectively reduces thermal expansion and prevents peeling of the side-surface conductor from the substrate, maintaining structural integrity and high-frequency characteristics.
Implementation Method 1
a side-surface conductor on at least a portion of a side surface of the multilayer body and made of a metallic material with a coefficient of thermal expansion whose difference from a coefficient of thermal expansion of the resin base-material layers in a plane direction is smaller than a difference from a coefficient of thermal expansion of the resin base-material layers in the thickness direction
Data Source
AI summary
A resin multilayer substrate includes a multilayer body including resin base-material layers in a thickness direction, a side-surface conductor on at least a side surface of the multilayer body and made of a metallic material with a coefficient of thermal expansion whose difference from a coefficient of thermal expansion of the resin base-material layers in a plane direction is smaller than a difference from a coefficient of thermal expansion of the resin base-material layers in the thickness direction, a circuit component in the multilayer body and defining a circuit, and inner conductors in the multilayer body, located between the side-surface conductor and the circuit component along the side-surface conductor, and at least partially overlapping each other when viewed in the thickness direction, each of the inner conductors being one of a dummy conductor and a ground conductor.