Circuit Board Solder Resist Support for Fine Pattern Collapse
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Solution Overview
Problem
Conventional circuit boards with fine circuit patterns face issues with the outermost circuit pattern collapsing due to the lack of a supporting structure in open regions, leading to reliability problems.
Innovation Solution
A circuit board with a layered solder resist structure, where the solder resist is divided into different regions with varying heights, is used to support and protect the outermost circuit pattern. This is achieved through a stepwise exposure and development process, ensuring the solder resist remains in key areas to prevent collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the circuit line width is reduced to increase circuit integration, then the degree of circuit integration is improved, but the circuit pattern becomes more prone to collapse during etching
Solution Approach 1:
The patent applies preliminary action by forming a supporting layer of solder resist material before the etching process. This supporting layer is deposited on the substrate and extends beyond the circuit pattern boundaries, providing structural support during subsequent etching operations. The supporting layer is removed after etching is complete, having fulfilled its temporary support function. This preliminary structural preparation prevents fine circuit patterns from collapsing during the etching process while enabling high circuit integration.
2Manufacturing precision
If the circuit pattern is made finer to reduce line width, then the circuit integration is improved, but the outermost circuit pattern easily collapses
Solution Approach 1:
The patent applies local quality by creating a supporting layer with spatially varying properties. The solder resist material is deposited to form a layer that extends beyond the circuit pattern boundaries, providing localized support where needed. The supporting layer has different heights and densities in different regions - thicker and more substantial at the edges and corners where fine patterns are most vulnerable, and thinner or absent in the center regions. This localized structural reinforcement protects fine circuit patterns from collapse without interfering with the overall circuit functionality.
3Reliability
If a supporting structure is added to protect the outermost circuit pattern, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent applies the discarding and recovering principle by using a temporary supporting layer of solder resist material that is deliberately designed to be removed after serving its protective function. The supporting layer is deposited before etching to provide structural support for fine circuit patterns during the vulnerable etching process. Once the etching is complete and the circuit patterns have been formed and stabilized, the supporting layer is removed through standard photoresist stripping processes. This temporary structure enables high-reliability fine pattern fabrication without permanently increasing device complexity, as the supporting material is discarded after fulfilling its protective role.
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 solution effectively prevents the collapse of the outermost circuit pattern, enhancing the reliability of the circuit board by providing necessary support and protection, especially in fine circuit pattern designs.
Implementation Method 1
a circuit board including a solder resist having a layered structure having a different height for each area by performing a stepwise exposure and development process of the solder resist
Data Source
AI summary
A circuit board according to an embodiment comprises: an insulating layer including first to third regions; an outer layer circuit pattern disposed on the upper surface of the first to third regions of the insulating layer; and a solder resist including a first part disposed in the first region of the insulating layer, a second part disposed in the second region, and a third part disposed in the third region, wherein the outer layer circuit pattern has a first height, the third part of the solder resist is disposed on the upper surface of the outer layer circuit pattern to have a second height, the first region includes a first sub-region and a second sub-region, the first part includes a first sub-part disposed in the first sub-region and a second sub-part disposed in the second sub-region, the upper surface of the first sub-part is located to be higher than the upper surface of the outer layer circuit pattern and lower than the upper surface of the third part, the upper surface of the second sub-part is located to be lower than the upper surface of the outer layer circuit pattern, and the surface roughness of the third part of the solder resist is different from the surface roughness of the first part of the solder resist.