Transparent Silicone Coating for Optoelectronic Modules
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Solution Overview
Problem
Current methods for coating optoelectronic chip-on-board modules with UV and temperature-resistant materials are inadequate, as they either compromise light radiation intensity, are not UV-stable, or require complex and heavy glass frames, leading to inefficiencies in space utilization and thermal expansion issues.
Innovation Solution
A method involving a transparent, UV and temperature-resistant silicone coating applied under elevated atmospheric pressure, which fully encapsulates the module, including the edges, using a silicone mold that allows for complete immersion and curing of the carrier with optoelectronic components, ensuring comprehensive protection and optimal space utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plastic dam is applied to enclose the carrier surface for coating, then the liquid filling compound can be contained without flowing away, but the plastic dam is not transparent and impairs light radiation intensity and light sensitivity
Solution Approach 1:
The patent removes the plastic dam structure entirely and replaces it with a liquid silicone coating process. The carrier is immersed directly into the liquid silicone under elevated pressure, eliminating the need for any enclosing dam structure. This extraction of the harmful plastic dam component resolves the contradiction by allowing full light transparency while maintaining coating containment through the pressure-controlled liquid immersion process.
Solution Approach 2:
The patent replaces the mechanical plastic dam containment system with a pressure-controlled liquid immersion system. By applying elevated atmospheric pressure (4-10 bar) during the coating process, the liquid silicone is forced to uniformly coat the carrier surface without requiring any mechanical enclosing structures. This substitution eliminates the light-blocking plastic dam while maintaining effective coating containment.
2Ease of manufacture
If epoxy resin is used as the filling compound, then the coating can be applied effectively, but the epoxy resin is not UV and temperature resistant and ages quickly under UV exposure
Solution Approach 1:
The patent changes the material parameter from epoxy resin to liquid silicone, which fundamentally alters the chemical composition and properties of the filling compound. Liquid silicone possesses inherent UV and temperature resistance that epoxy resin lacks, while still maintaining ease of application through the liquid state and curing process. This material parameter change resolves the contradiction by providing both manufacturability and long-term reliability under UV exposure.
Solution Approach 2:
The patent employs liquid silicone as a composite material that combines the benefits of ease of application (liquid state, moldable) with superior UV and temperature resistance. The silicone material can be cured to form a durable, transparent coating that maintains its protective properties under harsh environmental conditions, resolving the contradiction between manufacturability and reliability.
3Reliability
If a glass frame or glass dome is glued on for transparent protection, then UV and temperature stability is achieved, but the frame assembly is complex and the weight is higher
Solution Approach 1:
The patent merges the frame structure and the protective coating into a single integrated liquid silicone coating process. Instead of separately assembling a glass frame and then applying coating, the liquid silicone directly coats the entire carrier surface including edges, eliminating the need for separate frame structures. This merging simplifies the assembly process while maintaining UV and temperature stability.
Solution Approach 2:
The patent uses a liquid silicone coating that forms a thin, flexible protective film over the carrier surface. This thin film approach replaces the thick, rigid glass frame structure, reducing weight while providing equivalent or superior protection. The liquid silicone cures to form a durable yet lightweight coating that maintains UV and temperature resistance without the complexity of frame assembly.
4Manufacturing precision
If the carrier is fully immersed in liquid silicone under elevated pressure, then complete surface coverage including edges is achieved, but the process requires elevated atmospheric pressure equipment
Solution Approach 1:
The patent employs pneumatic pressure (elevated atmospheric pressure of 4-10 bar) to force the liquid silicone into complete contact with the carrier surface, including vertical and edge surfaces. The pressure differential drives the liquid coating material to uniformly cover all surfaces, ensuring complete coverage. This pneumatic approach provides precise control over the coating process and achieves manufacturing precision that gravity-only methods cannot attain.
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 method provides a transparent, UV and temperature-resistant coating that protects optoelectronic components over the entire surface, including edges, enhancing mechanical protection, maintaining optical efficiency, and allowing for seamless stacking and efficient use of space, while being suitable for high-performance UV-LED and photodiode applications.
Implementation Method 1
a liquid silicone is poured into a mold which is open at the top and has external dimensions which correspond to or exceed the external dimensions of the carrier; introducing the carrier into the mold, the optoelectronic component or the optoelectronic components being completely immersed in the silicone
Implementation Method 2
curing and crosslinking of the silicone with the optoelectronic components and the carrier
Implementation Method 3
the process steps a) and/or b) and/or c) are carried out under an elevated atmospheric pressure, in particular at an atmospheric pressure of between 4 and 10 bar, in particular between 5 and 7 bar
Implementation Method 4
curing and crosslinking of the silicone with the optoelectronic components and the carrier
Implementation Method 5
curing and crosslinking of the silicone with the optoelectronic components and the carrier
Data Source
Figure 1~3b
Figure 4~6
Figure 7A~8B
AI summary
The invention relates to a method for coating an optoelectronic chip-on-board module (1, 11-11'''). The optoelectronic chip-on-board module (1, 11-11''') comprises a flat support (2, 2') fitted with one or several optoelectronic components (4). The optoelectronic chip-on-board module (1, 11-11''') can have in particular at least one optics (23) which can encompass at least a primary optics (24) and, optionally, at least a secondary optics (25). In the method, the optoelectronic chip-on-board module (1, 11-11''') is coated with a transparent, UV- and temperature-resistant coating (12) made of a silicone. The method is characterized by the following method steps: a) casting a liquid silicone (21, 22) into a mould (20) which is open at the top and has external dimensions which correspond to or exceed the external dimensions of the support (2, 2'), b) introducing the support (2, 2') into the mould (20), wherein the optoelectronic component (4) or the optoelectronic components (4) are completely immersed in the silicone (21) and a surface of the support (2, 2') comes into contact with the entire surface of the silicone (21), or the support (2, 2') is at least partially immersed in the silicone (21), c) curing and cross-linking the silicone (21) with the optoelectronic components (4) and the support (2, 2'), and d) removing the support (2, 2') having the coating (12) from the cured silicone (21) from the mould (20).