PCB Bonding Structure With Insulating Films for Fine-Pitch Reliability
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Solution Overview
Problem
The increasing number of laminations in printed circuit boards leads to a higher defect rate and lower yield, particularly in substrates requiring fine circuits, due to accumulated defects during chip mounting.
Innovation Solution
A printed circuit board design featuring insulating films on conductor layers and a bonding portion with conductive filler to connect wiring portions, utilizing atomic layer deposition for thin insulating films of Al2O3, ZnO, or TiO2 to prevent unintended electrical connections and improve reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of laminations is increased to achieve fine circuits, then the circuit density and processing capability are improved, but the defect rate accumulates and yield decreases
Solution Approach 1:
The patent divides the circuit board into multiple independent wiring portions (first wiring portion, second wiring portion, etc.), each with its own insulating layer and conductor layer. This segmentation allows defects to be isolated to specific portions rather than affecting the entire board, thereby reducing the accumulation of defects across multiple laminations while maintaining fine circuit processing capability.
Solution Approach 2:
The bonding portion acts as an intermediary element between different wiring portions. It includes a bonding layer with conductive filler that electrically connects conductor layers from different wiring portions while maintaining physical separation. This intermediary structure prevents direct electrical contact between adjacent wiring portions, reducing the risk of short circuits and defect propagation across laminations.
2Manufacturing precision
If conductor layers are closely spaced to reduce pitch, then the circuit density is improved, but the risk of unintended electrical connections increases
Solution Approach 1:
The patent applies insulating films with specific properties (thickness, material composition including Al2O3, ZnO, TiO2, SiO2) at critical locations between conductor layers. The insulating film thickness is precisely controlled (e.g., 5 nm to 15 nm) to provide adequate electrical insulation while allowing close spacing of conductor layers. This local quality approach ensures reliable insulation where needed while maintaining high circuit density.
Solution Approach 2:
The bonding portion with conductive filler serves as an intermediary that selectively conducts electricity between conductor layers while the insulating films provide localized insulation. This intermediary structure enables controlled electrical connections only where intended, preventing unintended short circuits between closely spaced conductor layers.
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 reduces short circuit defects and enhances electrical reliability by preventing unintended electrical connections between conductor layers, thereby improving yield and reducing manufacturing defects.
Implementation Method 1
utilizing atomic layer deposition for thin insulating films of Al2O3, ZnO, or TiO2
Implementation Method 2
a bonding portion disposed between the first and second wiring portions to connect the first and second wiring portions, and including a bonding layer and a conductive filler dispersed within the bonding layer
Data Source
AI summary
A printed circuit board includes a first wiring portion including a first insulating layer and a first conductor layer disposed on at least one surface of the first insulating layer; a second wiring portion including a second insulating layer and a second conductor layer disposed on at least one surface of the second insulating layer facing the one surface of the first insulating layer; a bonding portion disposed between the first and second wiring portions to connect the first and second wiring portions, and including a bonding layer and a conductive filler dispersed within the bonding layer; and a first insulating film disposed on a portion of the first conductor layer.