Conformal Coating Thickness Control With Inline Optical Feedback
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Solution Overview
Problem
Conventional conformal coating thickness measurement is often manual and prone to errors, contamination, and incorrect results, while optical inspection requires calibration for each batch and comparison to a 'golden' sample.
Innovation Solution
A method for controlling a dispensing system that integrates a dispensing device with an inspection device, allowing for real-time measurement and adjustment of coating thickness and placement, with parameters such as pump speed, fluid pressure, and orifice opening being adjusted based on sensor data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual thickness measurement methods are used, then measurement can be performed, but contamination and incorrect results occur
Solution Approach 1:
The patent replaces manual mechanical measurement methods (wet film gages, eddy current meters, laser sensors) with an optical inspection system that uses cameras and image processing to measure coating thickness non-contactually, eliminating contamination risks from physical contact
Solution Approach 2:
The system creates an optical copy (image) of the coating surface and analyzes it digitally to determine thickness, replacing the need for physical contact with the coating material while maintaining measurement capability
2Productivity
If optical inspection is used, then inline measurement is possible, but calibration for every batch and comparison to golden sample is required
Solution Approach 1:
The system implements real-time feedback by continuously monitoring coating thickness during the dispensing process and automatically adjusting dispensing parameters to maintain target thickness, eliminating the need for batch-by-batch calibration and golden sample comparison
Solution Approach 2:
The inspection system performs self-calibration using reference features on the substrate itself, eliminating the need for external calibration procedures and golden samples while maintaining measurement accuracy across batches
3Measurement precision
If inspection is performed after substrate exits dispensing system, then measurement can be completed, but time is lost and errors propagate to subsequent substrates
Solution Approach 1:
The inspection is performed while the substrate is still in position within the dispensing system, before the substrate exits, allowing immediate detection and correction of thickness errors without delaying the process or allowing errors to propagate to subsequent substrates
4Measurement precision
If manual handling of substrates is performed, then measurement can be conducted, but coating placement may be compromised
Solution Approach 1:
The system replaces manual physical contact methods with non-contact optical inspection, eliminating the risk that handling operations will displace, smear, or otherwise compromise the coating placement while still enabling accurate thickness measurement
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 enables immediate error detection and correction, reducing the number of substrates coated with errors and eliminating the need for substrate ejection and remote inspection, thus improving coating consistency and efficiency.
Implementation Method 1
In an exemplary embodiment, the inspection device is a spectral interference laser sensor integrated with the dispensing device.
Data Source
AI summary
A method for controlling a dispensing system is provided, including the steps of dispensing, by a dispensing device, a coating material onto a substrate according to a first dispensing operation, inspecting, by an inspection device integrated with the dispensing device, the coating material applied to the first substrate, and altering the first dispensing operation based on the inspecting so that the coating material is dispensed onto a subsequent substrate according to a second dispensing operation. An associated coating machine is also provided.