Solder Resist Reprint Using 3D Defect Volume Filling
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Solution Overview
Problem
In the photolithography process for circuit board manufacturing, defects such as pinholes in the solder resist layer can lead to unintended exposure of metal layers, resulting in costly material and process losses due to the discarding of defective substrates.
Innovation Solution
A reprint apparatus and method that includes a defect checking unit to calculate the volume of defective areas, a material filling unit to precisely fill these defects with a filling material, and a curing unit to ensure the material is properly cured, using a 3D laser displacement sensor and EHD jet printing for accurate and quantitative filling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography process is used to manufacture circuit boards, then complex patterns can be formed on circuit boards, but defects such as pinholes may occur in the photoresist layer causing metal layer exposure
Solution Approach 1:
The patent performs preliminary defect detection and filling before final curing. The defect filling unit identifies pinholes and other defects in the photoresist layer, fills them with filling material, and cures the filled portions before the photoresist layer is completely cured. This preliminary action prevents defects from causing metal layer exposure during subsequent processing.
Solution Approach 2:
The patent introduces filling material as an intermediary substance to repair defects. The filling material is applied to defective portions of the photoresist layer, cured separately, and then the remaining uncured photoresist is cured. This intermediary filling material acts as a mediator to prevent defect propagation to the metal layer.
2Reliability
If all defective substrates are discarded, then product quality is maintained, but material costs and process costs are lost increasing overall production cost
Solution Approach 1:
The patent recovers defective substrates by filling and curing defects in the photoresist layer. Instead of discarding substrates with pinholes or other defects, the defect filling unit targets and fills only the defective portions, then cures the filled material. This allows the substrate to be reused, recovering material costs while maintaining product quality.
Solution Approach 2:
The patent applies local quality by filling only the defective portions of the photoresist layer rather than replacing the entire layer. The defect filling unit precisely targets pinholes and defects, applying filling material only where needed. This localized approach preserves the good portions of the photoresist layer and substrate, reducing material waste.
3Reliability
If filling material is applied to defective portions, then defects can be repaired, but material overflow and misplacement may occur
Solution Approach 1:
The patent uses feedback control through the defect detection unit, which identifies the location, size, and type of defects in the photoresist layer. This detection information is fed back to the defect filling unit, which adjusts the filling material application accordingly. The system monitors the filling process and makes real-time adjustments to prevent overflow and misplacement, ensuring precise material placement.
Solution Approach 2:
The patent applies partial action by filling only the defective portions rather than the entire photoresist layer. The defect filling unit selectively targets pinholes and defects, applying filling material only to the extent needed to repair the defects. This partial approach minimizes material usage and reduces the risk of overflow and misplacement.
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
This approach allows for the repair of defective solder resist layers on circuit boards, reducing material and process costs by enabling the reuse of substrates, while ensuring precise and efficient filling and curing of the defects, thus minimizing material overflow and misplacement.
Implementation Method 1
using a 3D laser displacement sensor
Implementation Method 2
EHD jet printing
Implementation Method 3
curing unit configured to cure the material filled in the defective portion
Data Source
AI summary
A reprint apparatus may include: a defect checking unit configured to check a defective portion in a solder resist layer of a circuit board; a material filling unit positioned above the circuit board to fill the defective portion with a filling material; and a curing unit configured to cure the material filled in the defective portion. The defect checking unit may be configured to calculate a volume of the defective portion, and the material filling unit may be configured to calculate a discharge amount of the filling material based on the calculated volume of the defective portion, and then discharge the filling material by the discharge amount.