A backlight reflective sheet

Abstract

The utility model discloses a kind of backlight reflector, it is related to keyboard backlight module technical field, including aluminium foil reflecting layer, the thickness of aluminium foil reflecting layer is 0.01-0.2 mm aluminium foil sheet, one side surface of aluminium foil reflecting layer is equipped with diffuse reflection structure, the diffuse reflection structure includes multiple micron level pits, the peak density of the micron level pit is 150-250 per / mm square, profile arithmetic average deviation Ra is 0.4-0.8 µm.The utility model replaces existing PET film by aluminium foil, adopts the backlight module of this reflector, can reduce the number of LED under the same brightness, improve the reflection efficiency of reflector, aluminium foil is metal key simultaneously, not easy to break, in addition, the heat conductivity coefficient of aluminium is higher, can evenly radiate LED lamp heat, prolong the service life and light efficiency stability of lamp.

Description

Technical Field

[0001] This utility model relates to the technical field of keyboard backlight modules, and in particular to a backlight reflector. Background Technology

[0002] As a key component of the backlight module in a backlit keyboard, the reflector is usually located at the bottom of the light guide plate. It is used to efficiently reflect the downward-scattered light back to the light-emitting surface to improve light energy utilization and brightness uniformity.

[0003] Currently, the industry widely uses 0.025T white PET film as a backlight reflector. However, existing PET films are prone to wrinkling and are formed by coating with white ink, resulting in poor light reflection. Due to the reliance on the scattering effect of the white film, its total reflectivity is not high, thus limiting further improvements in the brightness of the backlight module. Utility Model Content

[0004] The purpose of this invention is to provide a backlight reflective sheet to solve the problems mentioned in the background art, such as the existing PET film being prone to wrinkles and being a white film formed by coating with white ink, resulting in an insignificant light reflection effect and low total reflectivity due to the scattering effect of the white film.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a backlight reflective sheet, comprising an aluminum foil reflective layer, wherein the thickness of the aluminum foil reflective layer is 0.01-0.2 mm aluminum foil sheet, and a diffuse reflection structure is provided on one side surface of the aluminum foil reflective layer, wherein the diffuse reflection structure comprises multiple micron-level pits, the peak density of the micron-level pits is 150-250 pits / mm², and the profile arithmetic mean deviation Ra is 0.4-0.8 µm.

[0006] Preferably, the opening diameter of the micron-sized pit is 5-15 µm and the depth is 1-3 µm.

[0007] Preferably, the aluminum foil reflective layer is a first-series aluminum foil or an eighth-series aluminum foil.

[0008] Preferably, the aluminum foil reflective layer has a thermally conductive adhesive layer on the side facing away from the light source. The thermally conductive adhesive layer is a modified acrylic thermally conductive pressure-sensitive adhesive with a thermal conductivity ≥1 W / m·K and a thickness of 10-50 µm.

[0009] Preferably, the surface of the aluminum foil reflective layer is further covered with an anodized aluminum layer, which is located between the aluminum foil reflective layer and the thermally conductive adhesive layer. The anodized aluminum layer is fixedly connected to the aluminum foil reflective layer and the thermally conductive adhesive layer by hot pressing. The thickness of the anodized aluminum layer is 1-5 µm and the porosity is 10-30%, which is used to improve reflectivity and insulation withstand voltage.

[0010] The technical effects and advantages of this utility model are as follows: By replacing the existing white PET film with aluminum foil, this utility model uses a backlight module with this reflective sheet, which can reduce the number of LEDs under the same brightness and improve the reflection efficiency of the reflective sheet. At the same time, aluminum foil is a metal bond and is not easy to break. In addition, aluminum has a higher thermal conductivity, which can evenly dissipate the heat of the LED lamp, extend the lamp's service life and the stability of its light effect. Attached Figure Description

[0011] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0012] Figure 2 This is a schematic diagram of the backlight reflector structure of this utility model.

[0013] In the figure: 1. Aluminum foil reflective layer; 2. Micron-level pits; 3. Thermally conductive adhesive layer; 4. Anodized aluminum layer. Detailed Implementation

[0014] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0015] This utility model provides, for example Figure 1-2 The backlight reflective sheet shown includes an aluminum foil reflective layer 1 with a thickness of 0.01-0.2 mm. The aluminum foil reflective layer 1 has a diffuse reflection structure on at least one side surface, and the diffuse reflection structure includes a plurality of micron-sized pits 2 with a peak density of 150-250 pits / mm² and a profile arithmetic mean deviation Ra of 0.4-0.8 µm.

[0016] This invention improves the thermal conductivity of LEDs from 0.2 W / m·K to 237 W / m·K by replacing PET film with aluminum foil, reducing the LED junction temperature by 4-6 ℃. The density and roughness of the micron-level pits fall within the "Lambertian scattering window," reducing the specular component by 60%, and improving the 9-point brightness uniformity from 76% to 85%. It maintains a yield strength of 40 MPa even at 0.01 mm and can be rolled up for patching. At 0.2 mm, the weight is only +60 g / m², meeting the requirements for ultra-thin LEDs.

[0017] This allows backlit keyboards to reduce the number of LEDs by 8-10% at the same brightness, lowering the BOM cost by 0.15 USD per module and extending lifespan by 20%.

[0018] like Figure 1 As shown, the opening diameter of the micron-sized pit 2 is 5-15 µm and the depth is 1-3 µm;

[0019] With a micron-sized pit 2 opening of 5-15 µm and a depth of 1-3 µm, this size forms the optimal "Mie scattering" range with the visible light wavelength (450-650nm). While the reflectivity decreases by <1%, the brightness difference within a viewing angle of ±60° is <18%. The depth ≤3 µm avoids etching through the aluminum foil, which would cause a sharp drop in mechanical strength.

[0020] like Figure 1 As shown, the diffuse reflection structure is formed by etching or laser processing;

[0021] The etching process costs approximately USD 0.01 per piece, with Ra uniformity of ±0.05 µm. Laser processing is chemical-free, and changeover time is less than 5 minutes, making it suitable for small batches of various products.

[0022] like Figure 1 As shown, the aluminum foil reflective layer 1 is a first-series aluminum foil or an eighth-series aluminum foil;

[0023] The first series aluminum foil guarantees a thermal conductivity of 237 W / m·K; the 8 series has a 30% increase in yield strength, and can be made thinner than 0.008 mm without breaking. The appropriate series of aluminum foil can be selected according to the manufacturer's requirements.

[0024] like Figure 2 As shown, a thermally conductive adhesive layer 3 is provided on the side of the aluminum foil reflective layer 1 away from the light source. The thermally conductive adhesive layer 3 is a modified acrylic thermally conductive pressure-sensitive adhesive with a thermal conductivity ≥1 W / m·K and a thickness of 10-50 µm.

[0025] The side away from the light source uses a modified acrylic thermally conductive pressure-sensitive adhesive for heat conduction, resulting in a vertical thermal resistance of ≤0.05 K·in² / W, which is 25 times lower than that of PET tape. The peel strength is ≥1 N / mm, and it does not yellow at 85 ℃ / 1000 h. The thickness is 10-50 µm and is compatible with the tolerances of existing mounting machines, requiring no equipment modification and reducing manufacturing costs.

[0026] like Figure 1 As shown, the surface of the aluminum foil reflective layer 1 is covered with an anodized aluminum layer 4. The anodized aluminum layer 4 is located between the aluminum foil reflective layer 1 and the thermally conductive adhesive layer 3. The anodized aluminum layer 4 is fixedly connected to the aluminum foil reflective layer 1 and the thermally conductive adhesive layer 3 by hot pressing. The thickness of the anodized aluminum layer is 1-5 µm and the porosity is 10-30%. It is used to improve reflectivity and insulation withstand voltage.

[0027] By covering the surface of the aluminum foil reflective layer 1 with the surface of the anode layer, the reflectivity of the reflective sheet is increased by 2-3%; the pores form air microcavities, further scattering the light and reducing the shadow by 15%; the insulation withstand voltage is ≥2 kV, so even if the thermally conductive adhesive contains conductive fillers, it will not short-circuit; hot pressing at 120 ℃ / 0.3 MPa / 10 s can form an "anchor" with the acrylic adhesive, increasing the peel strength by 40%.

[0028] All data below are designed with a “aluminum foil reflective layer vs. 0.1 mm white PET reflective sheet” comparison, with sample size of 65 mm × 115 mm, 5-point sampling, n=5, and confidence level of 95% (t-distribution).

[0029] The aluminum foil grade is 1070-H18 (first series); the diffuse reflection process is 15 W fiber laser weaving three times; the density of micron-level pits is 200 ± 20 pcs / mm²; and Ra is 0.62 ± 0.05 µm.

[0030] In-plane thermal conductivity (W·m⁻¹·K⁻¹) 237 237 237 237 237 237 0.19 Vertical thermal resistance (K·in² / W) 0.018 0.012 0.009 0.006 0.005 0.004 0.260 Yield strength (MPa) 41 ± 2 45 ± 2 48 ± 2 52 ± 2 55 ± 2 58 ± 2 210 Warpage* (µm / 50mm) 180 ±20 55 ± 8 32 ± 5 18 ± 3 12 ± 2 8 ± 2 5 ± 1 550 nm reflectance (%) 91.5 93.1 93.8 94.0 93.5 92.8 97.1 9-point uniformity U (%) 82 84 85 85 84 83 76

[0031] Conclusion: Within a window with a thickness of 0.01-0.2 mm, the reflectivity is ≥92%, the uniformity is ≥82%, and the vertical thermal resistance is 25 times lower than that of PET.

[0032] Thermally conductive adhesive layer test: aluminum foil 0.05 mm, adhesive thickness 30 µm

[0033] A Modified propylene PSA 1.2 0.009 1.1 B Organosilicon PSA 1.8 0.007 0.9 PET control glue 0.25 0.260 1.0 -0.8 %

[0034] Conclusion: Modified acrylic PSA has a thermal conductivity ≥1 W·m⁻¹·K⁻¹, a thermal resistance 25 times lower than PET, and a peel strength ≥1 N / mm.

[0035] 0 0 0 0 0 0 3 1.2 12 +1.8 2.1 +25 5 2.5 20 +2.9 3.8 +35 8 4.0 28 +3.1 4.5 +40 10 5.2 32 +2.8 5.0 +38

[0036] Conclusion: When the diameter is 1-5 µm and the porosity is 10-30%, the reflectivity is increased by 2-3%, the breakdown voltage is ≥2 kV, and the peel strength is +40%.

[0037] Backlight module test: The test platform has a 5-inch keyboard backlight module with light from both sides, 12 LEDs, 0.3W per LED, and a total power of 3.6W.

[0038] The reflective sheets are made of: ① 0.05 mm aluminum foil with laser-etched texture;

[0039] ② 0.1 mm white PET.

[0040] Thermocouple: Type T, soldered to LED pads;

[0041] Infrared thermal imager: FLIR A325, emissivity 0.95, used for in-plane temperature distribution.

[0042] LED junction temperature Tj (°C) 68.2 ± 1.1 74.5 ± 1.3 -6.3 ℃ Maximum surface temperature of the reflector (°C) 58.4 ± 0.8 66.1 ± 1.0 -7.7 ℃ In-surface temperature difference (°C) 3.1 ± 0.3 8.4 ± 0.6 -5.3 ℃ Center brightness (cd / m²) 4850 ± 50 4750 ± 60 +100 cd / m² Power consumption (W) 3.60 3.60 0

[0043] Conclusion: Under high temperature and high humidity (85 ℃ / 85 %RH), after 500 h, the reflectivity of aluminum foil decreased by 0.8% and that of PET decreased by 1.1%. After 200 cycles of thermal cycling from -40 ℃ to 85 ℃, the warpage of aluminum foil increased by 5 µm and that of PET increased by 12 µm.

[0044] The experimental data above show that the backlight reflective sheet using the above technical solution maintains a reflectivity of ≥90%, while reducing the vertical thermal resistance by more than 25 times compared with the traditional PET reflective film, lowering the LED junction temperature by 4-6 ℃, and improving the brightness uniformity of 9 points to over 85%; the anodized aluminum layer improves the insulation withstand voltage to ≥2 kV and the peel strength by ≥40%, meeting the comprehensive requirements of high-end keyboards for ultra-thinness, high brightness, high uniformity, and high reliability.

[0045] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A backlight reflective sheet, comprising an aluminum foil reflective layer (1), characterized in that: The aluminum foil reflective layer (1) is an aluminum foil sheet with a thickness of 0.01-0.2 mm. One side surface of the aluminum foil reflective layer (1) is provided with a diffuse reflection structure, which includes multiple micron-sized pits (2). The peak density of the micron-sized pits (2) is 150-250 pits / mm², and the profile arithmetic mean deviation Ra is 0.4-0.8 µm.

2. The backlight reflective sheet according to claim 1, characterized in that: The opening diameter of the micron-sized pit (2) is 5-15 µm and the depth is 1-3 µm.

3. A backlight reflective sheet according to claim 1, characterized in that: The aluminum foil reflective layer (1) is a first-series aluminum foil or an eighth-series aluminum foil.

4. A backlight reflective sheet according to claim 1, characterized in that: The aluminum foil reflective layer (1) has a thermally conductive adhesive layer (3) on the side away from the light source. The thermally conductive adhesive layer (3) is a modified acrylic thermally conductive pressure-sensitive adhesive. The thermal conductivity of the thermally conductive adhesive layer (3) is ≥1 W / m·K and the thickness is 10-50 µm.

5. A backlight reflective sheet according to claim 1, characterized in that: The aluminum foil reflective layer (1) is also covered with an anodized aluminum layer (4). The anodized aluminum layer (4) is located between the aluminum foil reflective layer (1) and the thermally conductive adhesive layer (3). The anodized aluminum layer (4) is fixedly connected to the aluminum foil reflective layer (1) and the thermally conductive adhesive layer (3) by hot pressing. The thickness of the anodized aluminum layer is 1-5 µm and the porosity is 10-30%. It is used to improve reflectivity and insulation withstand voltage.

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