Mini LED Composite Film Encapsulation for Transmittance and Haze
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Solution Overview
Problem
Conventional encapsulation materials for Mini LED backlight modules struggle to balance transmittance and haze, affecting the performance and efficiency of display devices.
Innovation Solution
A composite film with a double-layer structure, comprising a first layer of ethylene-propylene copolymer or polyethylene terephthalate and a second layer of styrene-ethylene-butylene-styrene block copolymer or ethylene-vinyl acetate copolymer, is used to encapsulate light-emitting elements, achieving high transmittance and haze while maintaining stability and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional encapsulation materials (silicone, epoxy resin, OCA) are used, then protection of LED units is achieved, but the balance between transmittance and haze is difficult to achieve
Solution Approach 1:
The patent employs a composite film consisting of multiple layers with different thermoplastic materials (ethylene-propylene copolymer, PET, SEBS, EVA) to achieve both protective function and optimized optical properties. This composite structure allows simultaneous achievement of high transmittance and appropriate haze levels while maintaining reliable protection of the LED units.
Solution Approach 2:
The patent optimizes the melt flow rate parameters of the thermoplastic materials used in the composite film layers. By carefully selecting materials with specific MFR ranges and controlling the difference between layers (−11≤(R1−R2)≤11), the patent achieves optimal balance between transmittance, haze, and adhesion properties without compromising protection functionality.
2Ease of manufacture
If a single-layer encapsulation material is used, then manufacturing process is simple, but optical performance (transmittance and haze balance) is insufficient
Solution Approach 1:
The patent uses a multi-layer composite film structure where each layer contributes different optical properties. The first layer (ethylene-propylene copolymer or PET) and second layer (SEBS or EVA) work together to achieve the required transmittance and haze balance, demonstrating that complex optical performance can be achieved through material composition rather than process complexity.
Solution Approach 2:
Different layers of the composite film have different local qualities - the first layer provides structural stability and baseline optical properties, while the second layer optimizes adhesion and fine-tunes optical performance. This local differentiation allows each layer to be optimized for its specific function while maintaining overall manufacturing simplicity.
3Reliability
If encapsulation material with high adhesion is used, then stability is improved, but removal process becomes difficult and may damage components
Solution Approach 1:
The patent carefully controls the adhesion parameters by selecting thermoplastic materials with specific melt flow rates and by optimizing the temperature and pressure conditions during bonding. The adhesion is strong enough to provide stability during operation but can be reversed by heating, allowing easy removal without component damage. This is achieved by exploiting the thermoreversible nature of thermoplastic materials.
Solution Approach 2:
The adhesion properties of the composite film are dynamic rather than static - they change with temperature. At bonding temperature, the materials exhibit high adhesion for stable attachment, but at lower temperatures or when reheated, the adhesion decreases, enabling easy removal. This dynamic behavior resolves the contradiction between stability and ease of repair.
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 composite film provides high transmittance (>80%) and haze (>60%), enhancing luminous uniformity and allowing for easy removal without damaging electronic components, thus improving reworkability and product yield.
Implementation Method 1
disposing the composite film on the substrate via a thermocompression process to cover the light-emitting elements
Data Source
AI summary
A packaging structure and method for packaging are provided. The packaging structure includes a substrate, a plurality of light-emitting elements, and a composite film. The light-emitting elements are disposed on the substrate, and the composite film is disposed on the substrate, covering the light-emitting elements. The composite film includes a first layer and a second layer. The first layer includes a first thermoplastic material, wherein the melt flow rate (MFR) of the first thermoplastic material is R1, and the first thermoplastic material is an ethylene-propylene copolymer, polyethylene terephthalate, or a combination thereof. The second layer includes a second thermoplastic material, wherein the melt flow rate (MFR) of the second thermoplastic material is R2, and −11≤(R1−R2)≤11. The second thermoplastic material is a styrene-ethylene-butylene-styrene block copolymer, an ethylene-vinyl acetate copolymer (EVA), or a combination thereof.