Processing Machine UV Curing Heat-Sensitive PCBAs
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Solution Overview
Problem
Conformal coating processes for printed circuit board assemblies (PCBAs) are messy, hazardous, time-consuming, and costly, and existing UV curable coatings face challenges with heat-sensitive substrates like flex circuits due to high temperature risks from conventional UV emitters.
Innovation Solution
A machine is designed to process coatings using a combination of UV, visible, and IR radiation with closed-loop control, decoupling heating and UV exposure to prevent heat damage, and employing a conveyor system for efficient coating of PCBAs with UV curable materials, including DYMAX coatings, while controlling temperature and humidity to optimize curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional UV emitters are used for curing coatings, then curing speed is improved, but heat damage to substrates occurs
Solution Approach 1:
The patent segments the radiation spectrum into multiple distinct zones (UV zone with 300-400nm wavelength, visible light zone with 400-700nm wavelength, and IR zone with 700nm-1mm wavelength) that can be independently controlled. This allows the UV zone to cure the coating while the visible and IR zones provide controlled heating, separating the curing function from the heating function to prevent heat damage while maintaining curing speed.
Solution Approach 2:
The patent changes the radiation parameters by using a broad spectrum light source that emits across UV, visible, and IR ranges, and independently controls the intensity and wavelength distribution of each zone. This enables precise control over the energy delivered to the substrate, achieving rapid curing without excessive heat buildup that would damage heat-sensitive substrates.
2Loss of time
If heating and UV exposure are combined in one zone, then process time is reduced, but temperature control precision deteriorates
Solution Approach 1:
The patent divides the processing chamber into separate zones (UV curing zone, visible light zone, and IR heating zone) that can operate simultaneously but independently. This segmentation allows each zone to be optimized for its specific function while maintaining precise control, avoiding the temperature control issues that would arise from combining heating and UV exposure in a single zone.
Solution Approach 2:
The patent implements feedback control by using sensors to monitor temperature and radiation levels in each zone, and adjusting the intensity of light sources and heating elements accordingly. This closed-loop control system maintains precise temperature control even while multiple zones operate simultaneously to reduce overall process time.
3Ease of manufacture
If conventional coating processes are used, then coating application is simple, but mess and hazard increase
Solution Approach 1:
The patent replaces conventional mechanical coating methods (spray guns, dip tanks, brushes) with a deposition system that uses controlled environment and radiation curing. The coating is applied in a sealed chamber with controlled atmosphere, eliminating the mess and hazards associated with conventional open-air coating processes. The UV, visible, and IR radiation system then cures the coating without requiring additional chemical agents or complex mechanical operations.
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 machine enhances product quality, reduces operator risks, conserves energy, and allows for efficient processing of heat-sensitive substrates by ensuring precise temperature and radiation control, thereby improving coating efficiency and safety.
Implementation Method 1
a UV emitter to a PCBA to cure a UV curable coating material on the PCBA
Implementation Method 2
an IR emitter to the PCBA to heat the PCBA
Data Source
AI summary
A processing machine can include motors; at least one heater; first and second processing enclosures separated by a gap; an upper level conveyor that passes circuit assemblies through the first and second processing enclosures and the gap; a lower level conveyor that passes the circuit assemblies through the first and second processing enclosures and the gap; an elevator that transports the circuit assemblies between the upper level conveyor and the lower level conveyor; and a controller that includes circuitry operatively coupled to the motors and to the at least one heater.