Resin Multilayer Substrate Adhesion via Pattern Length Variation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing resin multilayer substrates face issues with weak joining strength between copper foils and resin sheets, leading to peeling problems, especially when exposed copper foils are subjected to external triggers, affecting junction performance and reliability.
Innovation Solution
A resin multilayer substrate design that enhances adhesion strength between conductive patterns and resin layers through a mechanism other than the anchor effect, utilizing a conductive via and a second resin layer with strategically positioned openings to cover a larger area around the conductive pattern, thereby improving mechanical and electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the surface roughness of the copper foil is increased to achieve the anchor effect, then the joining strength between copper foil and resin sheet is improved, but the electrical characteristics deteriorate
Solution Approach 1:
A resin layer is introduced as an intermediary substance between the copper foil and the external environment. This resin layer has high adhesion to the copper foil and provides mechanical protection, preventing peeling while maintaining the copper foil's smooth surface for good electrical characteristics. The resin layer acts as a mediator that transfers and distributes mechanical stresses, protecting the copper-resin interface from direct stress concentration.
2Strength
If the conductive pattern size is increased to improve adhesion strength, then the joining strength is enhanced, but the design flexibility deteriorates
Solution Approach 1:
The resin layer provides localized protection and adhesion enhancement at the copper foil interface without requiring changes to the overall conductive pattern geometry. The adhesion promotion is concentrated at the critical interface region, allowing the conductive patterns to maintain their original small sizes and flexible arrangements while still achieving strong joining strength through the resin's localized bonding action.
3Reliability
If the copper foil is exposed on the main surface for electrical connection, then the electrical connectivity is improved, but the peeling resistance deteriorates
Solution Approach 1:
A thin resin film or coating is applied over the exposed copper foil surfaces. This thin film maintains electrical connectivity by being conductive or allowing solder penetration while providing a flexible protective layer that prevents peeling. The thin film conforms to the copper pattern geometry and provides mechanical reinforcement without significantly increasing the overall structure thickness.
Data Source
AI summary
A resin multilayer substrate includes a first resin layer, a conductive pattern that covers a portion of the first resin layer, a conductive via connected to the conductive pattern, and a second resin layer that is overlaid on the first resin layer. The second resin layer includes an opening through which the conductive pattern is partially exposed. As seen in plan view, the opening includes an inner peripheral edge including a first portion that is spaced from the conductive via by a first distance, and a second portion that is spaced from the conductive via by a second distance. The conductive pattern has a length that starts from the inner peripheral edge of the opening to outside and extends under the second resin layer. The length of the conductive pattern at the second portion is greater than the length of the conductive pattern at the first portion.