Multilayer PCB Adhesive Structure for Peeling-Resistant Bonding
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Solution Overview
Problem
Existing multilayer printed wiring boards face issues with peeling and stress between conductor circuits and interlayer resin insulating layers, particularly when the number of layers increases or the board size grows, leading to potential cracking and uneven electrical properties.
Innovation Solution
A printed wiring board design featuring a smooth adhesive layer with protruding parts between the conductor and resin insulating layers, ensuring strong adhesion and uniform electrical properties, using a nitrogen-based organic compound adhesive layer with smooth film and protrusions to enhance bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional multilayer printed wiring boards are manufactured with increased number of layers or larger board sizes, then the functionality and capacity of the board are improved, but peeling and stress between conductor circuits and interlayer resin insulating layers occur leading to cracking and uneven electrical properties
Solution Approach 1:
The invention applies different surface qualities to different regions of the conductor layer. The upper surface is kept smooth for electrical performance, while the side surface is formed with protrusions to enhance adhesive bonding. This local differentiation resolves the contradiction by providing both smooth electrical contact areas and high-adhesion bonding areas in the same component.
Solution Approach 2:
The protrusions are formed on the side surface of the conductor layer before the resin insulating layer is applied. This preliminary action creates pre-formed bonding anchors that ensure strong adhesion from the start, preventing peeling and cracking that would otherwise occur in high-capacity multilayer boards.
2Manufacturing precision
If the conductor layer surface is made smooth for good electrical properties, then signal transmission is improved, but adhesion to the resin insulating layer is reduced causing peeling
Solution Approach 1:
The conductor layer is given different surface qualities in different locations: the upper surface remains smooth for optimal electrical signal transmission, while the side surface develops protrusions that provide mechanical interlocking for strong adhesive bonding. This spatial differentiation of surface properties resolves the contradiction between smoothness for electricity and roughness for adhesion.
Solution Approach 2:
Instead of making the entire surface rough in one dimension, the invention creates protrusions that extend in the vertical dimension from the side surface. This dimensional approach allows the upper surface to remain smooth for electrical contact while the side surface gains bonding capability through vertically extending protrusions.
3Reliability
If adhesive layers are added to improve bonding between layers, then peeling is reduced, but the board complexity and manufacturing difficulty increase
Solution Approach 1:
The conductor layer itself generates the bonding enhancement features through protrusions on its side surface. This self-service approach eliminates the need for separate adhesive layers, as the protrusions provide the necessary mechanical interlocking directly. The structure serves its own bonding function, reducing overall complexity.
Solution Approach 2:
The protrusions act as intermediary bonding elements between the conductor layer and resin insulating layer. Instead of using a separate adhesive material layer, the protrusions mediate the bonding function by providing mechanical interlocking, thereby reducing structural complexity while maintaining bonding reliability.
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 design provides high-quality boards with reduced peeling and cracking, maintaining consistent electrical performance and minimizing signal propagation delays, even with multiple layers and larger sizes.
Implementation Method 1
an adhesive layer formed on the first conductor layer... ensuring strong adhesion and uniform electrical properties, using a nitrogen-based organic compound adhesive layer with smooth film and protrusions to enhance bonding
Data Source
AI summary
A printed wiring board includes an insulating layer, a first conductor layer formed on the insulating layer, an adhesive layer formed on the first conductor layer, a resin insulating layer formed on the insulating layer such that the adhesive layer is formed between the first conductor layer and the resin insulating layer, and a second conductor layer formed on the resin insulating layer. The first conductor layer is formed such that the first conductor layer has a smooth upper surface and a smooth side surface and that the adhesive layer has a smooth film formed on the smooth upper and side surfaces, and a protruding part protruding from the smooth film.