Wired Circuit Board Ground Layer Adhesion via Nested Insulating Openings
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Solution Overview
Problem
Conventional wired circuit boards face challenges in achieving sufficient adhesion of the ground layer to the insulating layers, leading to reliability issues in ground connections due to small contact areas between the side ground layer and openings in the insulating layers.
Innovation Solution
A wired circuit board design featuring a metal supporting layer, first and second insulating layers with strategically formed openings and inclined peripheral side surfaces, where the ground layer fills these openings to contact the metal supporting layer, enhancing adhesion by creating stepped portions for improved contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the first opening and the second opening are formed flush along the thickness direction, then the manufacturing process is simple, but the contact area between the side ground layer and each opening is small, resulting in low adhesion
Solution Approach 1:
The patent transitions from a two-dimensional flush opening configuration to a three-dimensional nested opening configuration, where the first opening is surrounded by the second opening when projected in the thickness direction. This dimensional change creates stepped portions that significantly increase the contact area between the ground layer and insulating layers, thereby improving adhesion while maintaining manufacturing feasibility through sequential opening formation processes.
2Device complexity
If the openings are formed with small contact area, then the insulating layer structure is simple, but the adhesion of the side ground layer to the insulating layer is low
Solution Approach 1:
The patent divides the single opening structure into two segmented openings (first opening and second opening) with different sizes and positions. The first opening is formed in the first insulating layer, and the second opening is formed in the second insulating layer such that the first opening is surrounded by the second opening when projected. This segmentation creates multiple contact surfaces and stepped portions, significantly increasing the adhesion area between the ground layer and insulating layers without overly complicating the overall structure.
3Ease of manufacture
If the ground layer fills the opening flush, then the filling process is simple, but the contact area with the metal supporting layer is limited
Solution Approach 1:
The patent employs a nested opening configuration where the first opening (in the first insulating layer) is surrounded by the second opening (in the second insulating layer) when projected in the thickness direction. This creates a stepped structure that extends the ground layer's contact area with the metal supporting layer in the planar dimension, allowing the ground layer to fill both openings sequentially and achieve larger contact area without complicating the filling process.
Data Source
AI summary
A wired circuit board includes a metal supporting layer, a first insulating layer, a conductive layer, a second insulating layer, and a ground layer. The first opening of the first insulating layer is surrounded by the second opening of the second insulating layer when projected in the thickness direction, and the ground layer fills the first opening via the second opening so as to come in contact with an upper surface of the metal supporting layer. Alternatively, the first opening surrounds the second opening when projected in the thickness direction, the second insulating layer fills a peripheral end portion of the first opening, and the ground layer fills the second opening so as to come in contact with the upper surface of the metal supporting layer.