Vacuum Lamination for Conformal LED Coating
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Solution Overview
Problem
The two-step vacuum lamination technique for forming conformally coated articles, such as LED devices, is limited by partial curing of the binder material in the first heating step, leading to processing time constraints and defects, and restricts the use of varying LED heights and binder/phosphor material combinations.
Innovation Solution
A single-step vacuum lamination method where a preformed lamination layer is heated to soften the middle portion, forming a gastight seal, and then conformally coated over the object by increasing gas pressure within the vacuum chamber, allowing for a wider range of binder compositions and LED array heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a two-step vacuum lamination technique is used with independent heating steps, then the preformed lamination layer can be heated to achieve flow in the uncured thermosetting binder material, but the binder material begins to cure during the first heating step, reducing flow characteristics and causing the layer to become too stiff for subsequent conformal coating
Solution Approach 1:
The patent combines the heating and conformal coating operations into a single integrated step. The heating element simultaneously heats the preformed lamination layer to achieve binder flow and applies the conformal coating in one continuous process, eliminating the intermediate curing issue that occurs with separate heating steps.
Solution Approach 2:
The heating and conformal coating process continues uninterrupted in a single operation. The binder material maintains its flow characteristics throughout the entire process because the heating is applied continuously during the coating deposition, preventing the partial curing that would occur with intermittent heating steps.
2Productivity
If the first heating step is performed to achieve flow in the binder material, then the lamination layer begins to cure and reduces processing time, but this limited processing time prevents conformal coating on arrays of LEDs with varying heights and restricts binder material choices
Solution Approach 1:
By merging the heating and conformal coating steps into one simultaneous operation, the patent extends the effective processing window. The heating is applied continuously during coating deposition rather than in a separate preliminary step, allowing sufficient time for both high-speed processing and complete conformal coating of varied LED structures.
Solution Approach 2:
The patent modifies the temporal parameters of the heating process by applying heat continuously during the coating operation rather than in a separate preliminary step. This parameter change allows the binder material to maintain optimal flow characteristics throughout the entire coating process, enabling accommodation of varying LED heights and different binder material viscosities.
3Manufacturing precision
If precise control of curing conditions is maintained during two-step vacuum lamination, then processing can be managed, but the processing time is still limited due to partial curing in the first heating step
Solution Approach 1:
The heating and coating process operates continuously in a single step without interruption. The binder material is heated and coated simultaneously, eliminating the time loss associated with transitioning between separate heating and coating steps, and preventing the partial curing that would occur during any delay between steps.
Solution Approach 2:
The patent merges the heating and conformal coating operations into one integrated process step. This eliminates the sequential time penalty of performing heating first and then coating, allowing both functions to occur concurrently and reducing total processing time while maintaining precise control over the coating quality.
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 method enables defect-free, repeatable conformal coatings with an increased processing window, allowing for the use of diverse phosphor levels and binder compositions, and conformal coating over LEDs of varying heights.
Implementation Method 1
heating said preformed lamination layer to a first temperature sufficient to soften said middle portion of said preformed lamination layer
Implementation Method 2
applying a vacuum within the vacuum chamber... conforming said softened preformed lamination layer over said LED array by increasing the gas pressure within the vacuum chamber
Data Source
Figure 1~2
Figure 3~4
Figure 5~5A
AI summary
Vacuum lamination methods for forming conformally coated articles having a preformed lamination layer conformally coated to or on an object such as an LED array are provided. These vacuum lamination methods utilize a single heating step to heat a middle portion of the preformed lamination layer to a flowable condition prior to the preformed lamination layer being conformally coated over the article, such as the array of light emitting diodes disposed on an inner portion of a first side of a submount wafer.