Filled Polyimide Layer for LED Thermal Control
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Solution Overview
Problem
Conventional reflective materials for lighting systems face issues such as insufficient whiteness, reflectance, thermal stability, UV stability, mechanical properties, and deformation during soldering, which hinder their effectiveness in lighting assemblies and thermal control blankets.
Innovation Solution
A filled polyimide layer composed of 50-75 weight percent polyimide derived from 3,3′,4,4′-biphenyltetracarboxylic dianhydride and 2,2′-bis(trifluoromethyl)benzidine, combined with a white pigment particulate filler and electrically conductive circuit traces, providing enhanced reflectivity, thermal stability, and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional reflective materials are used, then the structure is simple, but the reflectance and whiteness are insufficient
Solution Approach 1:
The patent employs a composite reflective material consisting of a polyimide matrix combined with specific white pigment particles (titanium dioxide, zinc oxide, or zinc sulfide) in controlled ratios. This composite structure achieves superior reflectance and whiteness (L-value ≥85) by combining the thermal stability of polyimide with the high reflectivity of white pigments, resolving the contradiction between simple structure and insufficient reflectance performance.
2Stability of the object's composition
If conventional reflective materials are used, then the manufacturing process is simple, but the thermal stability and color stability are poor
Solution Approach 1:
The patent specifies precise compositional parameters: polyimide content of 60-80 wt%, white pigment content of 20-40 wt%, and pigment particle size of 0.1-2.0 micrometers. These controlled parameters ensure the material maintains color stability (ΔE ≤5) and structural integrity under thermal exposure up to 200°C, while remaining manufacturable through standard mixing and coating processes.
3Strength
If conventional reflective materials are used, then the application process is simple, but the mechanical properties and deformation resistance are poor
Solution Approach 1:
The polyimide-white pigment composite creates a synergistic material system where the polyimide matrix provides mechanical strength and flexibility, while the white pigment particles enhance reflectance. The controlled particle size (0.1-2.0 micrometers) ensures good dispersion and bonding, preventing deformation during soldering and maintaining mechanical integrity without requiring complex multi-layer structures.
4Stability of the object's composition
If conventional reflective materials are used, then the cost is low, but the UV stability and color stability are poor
Solution Approach 1:
The patent selects specific white pigments (titanium dioxide, zinc oxide, zinc sulfide) known for their UV resistance and specifies their content ratio within 20-40 wt%. The polyimide base material also provides inherent UV stability. These parameter specifications ensure the material maintains color stability (ΔE ≤5) under UV exposure without requiring additional UV-absorbing additives or complex protective coatings.
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 solution achieves high reflectivity, maintains color and mechanical integrity under thermal exposure, and withstands soldering processes without deformation, simplifying the structure and production of light emitting diode assemblies and thermal control blankets.
Implementation Method 1
a white pigment particulate filler with a mean particle size less than 1.9 microns and in an amount from 20 to 50 weight percent of the filled polyimide layer
Data Source
AI summary
The present disclosure relates generally to a light emitting diode assembly and a thermal control blanket. The light emitting diode assembly and the thermal control blanket have advantageous reflective and thermal properties.