Circuit Board Outer Pattern Support via Solder Resist Segmentation
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Solution Overview
Problem
Conventional circuit boards with fine circuit patterns on the outermost side are prone to collapse due to external impacts, and existing methods like the ETS method face challenges in manufacturing multi-layer boards, leading to productivity issues and pattern damage during the lamination process.
Innovation Solution
A circuit board structure with an insulating layer divided into regions, featuring a solder resist with different heights and surface roughness levels, and a primer layer to support the outer circuit pattern, allowing for copper dissolution and adhesive formation to stabilize the pad height and prevent resin residue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the circuit pattern is made fine to achieve miniaturization and integration, then the circuit board can support higher integration and smaller size, but the outermost circuit pattern becomes prone to collapse due to external impacts
Solution Approach 1:
The patent applies beforehand cushioning by forming a support layer of solder resist material beneath the outermost circuit pattern before finalizing the board structure. This support layer acts as a cushion that prevents collapse of the fine circuit pattern under external impacts, while maintaining the miniaturized and integrated design goals.
2Manufacturing precision
If the ETS method is used to embed copper foil in insulating layer for finer circuit pattern, then circuit pitch can be made fine without etching loss, but manufacturing multi-layer boards becomes difficult leading to productivity issues and pattern damage during lamination
Solution Approach 1:
The patent applies segmentation by dividing the circuit pattern formation into separate stages: inner circuit patterns are formed using conventional methods on insulating layers, while outer circuit patterns are formed separately using electroless plating on a support layer. This segmentation allows each type of circuit to be optimized independently, avoiding the productivity and pattern damage issues associated with embedding all circuits during lamination.
Solution Approach 2:
The patent introduces a support layer as an intermediary element between the insulating layer and the outer circuit pattern. This support layer provides mechanical strength during manufacturing and serves as a foundation for forming precise outer circuits through electroless plating, thereby achieving both high precision and productivity.
3Ease of operation
If the outer circuit pattern protrudes on the insulating layer to be accessible, then the circuit can be connected externally, but the circuit pattern easily collapses under external impact
Solution Approach 1:
The patent forms a support layer of solder resist material beneath the outer circuit pattern before completing the board assembly. This support layer provides mechanical strength and prevents collapse of the protruding circuit pattern, while the pattern remains accessible for external connections.
Solution Approach 2:
The patent creates a composite structure where the outer circuit pattern (copper foil) is formed on a support layer (solder resist material) which itself is on the insulating layer. This composite structure combines the electrical conductivity of copper with the mechanical strength of solder resist, enabling both accessibility and strength.
4Reliability
If solder resist is applied to protect the circuit pattern, then the circuit pattern is protected from damage, but resin may remain on the surface of the circuit pattern in the SR open region
Solution Approach 1:
The patent applies local quality by creating an SR open region where the solder resist layer is intentionally made thinner or removed in specific areas. This allows the circuit pattern surface to be exposed and clean in regions where it needs to be accessible, while maintaining protection in other regions. The support layer provides underlying protection even where solder resist is reduced.
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 proposed structure enhances the reliability of the circuit board by preventing resin residue and ensuring stable support for the adhesive, thereby reducing the risk of pattern collapse and improving manufacturing efficiency.
Implementation Method 1
allowing for copper dissolution and adhesive formation to stabilize the pad height
Implementation Method 2
allowing for copper dissolution and adhesive formation to stabilize the pad height
Data Source
AI summary
A circuit board according to an embodiment includes an insulating layer including first to third regions; an outer circuit pattern disposed on upper surfaces of the first to third regions of the insulating layer, and a solder resist including a first part disposed on the first region of the insulating layer, a second part disposed on the second region, and a third part disposed on the third region, wherein the outer circuit pattern includes a first trace disposed on an upper surface of the first region of the insulating layer; a first pad disposed on an upper surface of the first region of the insulating layer; and a second trace disposed on an upper surface of the third region of the insulating layer; wherein an upper surface of the first part of the solder resist is positioned lower than an upper surface of the first trace; and a height of the first trace is different from a height of the first pad.