Material stacking structure of low-temperature focusable liquid crystal lens and reliability enhancing method

Abstract

The invention discloses a material stack structure of a low-temperature focus-adjustable liquid crystal lens applied to the field of flexible optical materials and a reliability enhancing method, a material stack comprises an upper transparent base material, a lower transparent base material, a transparent electrode layer, an orientation layer, a spacing layer, a liquid crystal layer and a frame sealing layer, and packaging is completed under the condition that the manufacturing temperature is not higher than 100 DEG C. The water vapor transmission rate is reduced to be lower than a preset threshold value through the barrier layer, and the stress release structure reduces warping, delamination or atomization caused by bending and temperature and humidity circulation through the flexible area, the slotting / corrugation, the gradual change glue layer, the local thickening layer and / or the buffer layer. Besides, by constructing a bending and thermal stress model, CTE matching material selection and barrier layer thickness design, and combining accelerated reliability test identification failure mechanisms such as temperature and humidity / bending / voltage life and the like, closed-loop updating of'model-test-reason code-recharge 'is formed; therefore, the mass production consistency and the long-term reliability of the windable and focusable liquid crystal lens are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flexible optical materials, in particular to a material stack structure of a low-temperature tunable liquid crystal lens and a reliability enhancement method. BACKGROUND

[0002] With the development of wearable display, smart glasses and variable focus optical system, tunable lenses need to meet the requirements of ultra-thinness, bendability / rollability, low-power driving and long-term environmental stability. Liquid crystal lenses are widely studied due to their low driving voltage, fast response, high transmittance and other advantages.

[0003] However, in order to realize rollability and thinness, the device often uses flexible transparent substrates such as PEN / TAC / COP / PET, and the upper limit of the temperature resistance of such substrates is low (limited by glass transition temperature and thermal shrinkage rate), so that the processes of electrode deposition, sealing and curing, and barrier coating must be completed within a low-temperature manufacturing window.

[0004] In a multi-layer material stack, the coefficients of thermal expansion (CTE), elastic modulus and moisture expansion coefficient of each layer of material are significantly different, and the device is prone to interface shear stress concentration, frame sealing fatigue, liquid crystal cavity high drift, warping and local fogging when it undergoes temperature changes or bending and rolling, thereby causing wavefront distortion and degradation of imaging quality.

[0005] At the same time, liquid crystal and transparent electrodes are sensitive to water vapor and oxygen, and water vapor intrusion can cause liquid crystal resistivity to decrease and electro-optic response to drift; transparent electrodes such as ITO may corrode or break in a humid environment. It is often difficult to meet long-term reliability and production consistency by relying only on traditional single-layer packaging and single-sealing.

[0006] Therefore, there is an urgent need for a material stack and reliability closed-loop solution for low-temperature processes and rollable applications, which optimizes the selection of materials, barrier and sealing, stress release structure, accelerated testing and failure backfilling, etc. to form a reusable and traceable engineering system. SUMMARY

[0007] The core of the present application is to propose a material stack structure of a low-temperature tunable liquid crystal lens and a reliability enhancement method, forming a closed loop of "structure-model-test-backfilling", which meets the requirements of long-term reliability in low-temperature manufacturing window and rollable use scenarios.

[0008] To solve the above problems, the technical scheme adopted by the present application is as follows.

[0009] The material stack structure of the low-temperature tunable liquid crystal lens comprises an upper transparent substrate, a lower transparent substrate, a transparent electrode layer, an orientation layer, a spacer layer and a liquid crystal layer arranged in sequence on the upper transparent substrate, and a frame sealing layer arranged on the lower transparent substrate. The upper limit of the manufacturing temperature of the material stack is not higher than 100℃, the material stack further comprises at least one of a barrier layer for reducing water vapor transmission rate and a stress release structure for reducing warpage, delamination or fogging caused by bending and temperature and humidity cycling.

[0010] Further, the upper transparent substrate and the lower transparent substrate are one of PEN, TAC, COP or a composite layer thereof, and at least one side of the upper transparent substrate and the lower transparent substrate is coated with a low WVTR barrier coating layer.

[0011] Further, the barrier layer is a multilayer structure of inorganic layers and organic layers alternately stacked, for reducing the water vapor transmission rate to below a preset threshold and inhibiting oxygen intrusion.

[0012] Further, the frame sealing layer comprises a sealing frame glue line, a secondary sealing structure, a filling port and an exhaust channel, the sealing frame glue line is arranged outside the upper transparent substrate and the lower transparent substrate and forms a liquid crystal cavity, and the filling port and the exhaust channel are arranged on the sealing frame glue line.

[0013] Further, the stress release structure comprises a compliant region composed of at least one of a graded adhesive layer, a slotted or corrugated structure, a locally thickened region and a buffer layer, so that the shear stress peak at the interface between the frame sealing layer and the substrate is below a preset threshold.

[0014] Further, the transparent electrode layer comprises at least one of ITO, metal mesh or conductive polymer, and the surface of the transparent electrode layer is coated with at least one of an anti-corrosion protective layer or a lead passivation layer.

[0015] Further, the spacer layer comprises spherical spacers or columnar spacers arranged in the liquid crystal cavity, or a micro-pillar array arranged on the surface of the upper transparent substrate and / or the lower transparent substrate, for defining the cavity height of the liquid crystal cavity and inhibiting cavity height drift.

[0016] Further, the material stack satisfies the stability criterion of haze and wavefront error when the bending radius R is not less than a preset value, and the preset value is determined according to the target winding diameter and the long-term fatigue life.

[0017] Further, the material stack further comprises one of a surface hard coating layer and an anti-reflection layer to improve wear resistance and transmittance and enhance compatibility with subsequent assembly processes.

[0018] Further, the material stack structure supports repair sealing, that is, when the leakage detection is determined to be repairable, the frame sealing layer is supplemented with glue without removing the transparent electrode layer, forming a glue supplementing ring or forming a secondary sealing cap for the filling port and the exhaust channel.

[0019] Further, the low-temperature manufacturing window of the material stack includes three-parameter constraints of solidification energy, solidification time and lamination pressure, and is bound with traceability data package to support cross-batch consistency control.

[0020] A reliability enhancement method for low-temperature rollable tunable-focus liquid crystal lens material stack, comprising the following steps: S1, constructing a bending or thermal stress model of the multi-layer stack and determining the neutral axis position; S2, selecting CTE matching materials, barrier layer structure and stress release structure according to the model; S3, performing low-temperature packaging and sealing under the condition that the manufacturing temperature is not higher than 100℃; S4, performing accelerated testing of temperature and humidity, bending and voltage life of the product and recording key measurement results; S5, updating the material formula or low-temperature process window according to the failure mechanism and test data and forming a traceability record.

[0021] Further, the bending strain of the multi-layer stack is approximated as ε≈t / (2R), and the neutral axis position Z0=Σ(E i ·t i ·z i ) / Σ(E i ·t i ) is calculated according to the laminate theory.

[0022] Further, the interlayer thermal stress under thermal cycling is approximated as σ i ≈Ei(α i -α ref )ΔT / (1-ν i ), and the σ i peak, warping amount and interfacial shear stress are used as material selection and structure screening indexes.

[0023] Further, the water vapor intrusion is evaluated by Fick diffusion model , and the equivalent thickness L and the number of layers of the barrier layer are determined according to the constraint that the internal surface water content c does not exceed the threshold value c_th within the service life.

[0024] Further, the accelerated test life is extrapolated by using Arrhenius acceleration factor AF=exp[Ea / k·(1 / T use -1 / T test )], where Ea is the equivalent activation energy and k is the Boltzmann constant.

[0025] Further, the failure mode matrix is constructed by combining temperature and humidity cycling, bending cycling and voltage life test, and the main failure mechanism and its correlation with material or process parameters are output.

[0026] Further, interface peel strength or shear strength measurement is performed on failed samples and calibrated with bending or thermal stress model to update the glue layer formulation or the compliance zone structure parameters.

[0027] Further, haze H and wavefront error W RMS Set stability criterion: |ΔH|<τ_H and |ΔW RMS |<τ_W, where ΔH=H after -H before , ΔW RMS =W RMS，after -W RMS，before .

[0028] Further, pressure decay or tracer gas method is used to detect the seal leakage, which is the leakage of the frame seal layer and its filling port or secondary seal, and the leakage rate is written into the traceability data package as a rejection index.

[0029] Further, the CTE matching of the material stack, the number or thickness of the barrier layer, and the compliance zone geometry are iteratively optimized to reduce warping according to the accelerated test and metrology results, wherein each iteration at least includes: updating the model parameters, generating candidate solutions, trial verification and regression comparison.

[0030] Further, statistical process control is performed on the low-temperature process window, and drift alarm is output to trigger re-calibration or process rollback to avoid the accumulation of implicit failures.

[0031] Further, reliability test data is associated with a cause code to support root cause analysis, and manufacturing parameters are fed back, and the cause code is used to characterize at least one failure mode or abnormal source.

[0032] Further, the traceability data package is hashed and a verifiable audit record is generated to ensure that the material batch, process window, test results, and cause code are not tampered with.

[0033] Further, steps S1-S5 are controlled by a controller, which updates at least one threshold parameter based on the accelerated test or online metrology results, and writes the threshold version, the cause code of the update trigger, and the difference before and after the update into the traceability data package or the traceability log.

[0034] Compared with the prior art, the advantages of the present application are: (1) Strengthen the barrier and seal at the same time under the constraint of low-temperature manufacturing, improve the stability of liquid crystal and electrode in a humid heat environment.

[0035] (2) Reduce interface stress concentration through compliance zone and geometric stress release features, improve the reliability of rollable and repeated bending.

[0036] (3) Binding model, accelerated testing, root cause code and traceability data package to form a reliable closed loop of mass production traceability, improve cross-batch consistency and reduce rework cost. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 A schematic diagram of the material stack profile of the present application; Figure 2 A schematic diagram of the neutral axis and bending strain distribution in the multi-layer stack of the present application; Figure 3 A schematic diagram of the CTE mismatch stress and warpage under thermal cycling of the present application; Figure 4 A schematic diagram of the barrier layer and water vapor diffusion path of the present application; Figure 5 A schematic diagram of the frame sealing layer, filling port or exhaust channel, and leak detection or repair process of the present application; Figure 6 A schematic diagram of the stress release structure of the present application; Figure 7 A schematic diagram of the accelerated reliability test matrix of the present application; Figure 8 A schematic diagram of the typical failure mechanism of the present application; Figure 9 A schematic diagram of the life model and acceleration factor conversion of the present application; Figure 10 A simulated SEM style schematic diagram of the barrier layer interface and micro-defects of the present application. DETAILED DESCRIPTION

[0038] The technical solutions will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application.

[0039] First embodiment: As Figure 1 , the material stack structure of the low-temperature focus-adjustable liquid crystal lens includes, from top to bottom, an upper transparent substrate, a transparent electrode layer, an orientation layer, a spacer layer (for defining the cavity height h of the liquid crystal cavity), a liquid crystal layer, a lower transparent substrate, and a frame sealing layer. To improve surface wear resistance and transmittance and enhance compatibility with subsequent assembly processes, a hard coating or anti-reflection layer can be formed on the outside of the material stack structure.

[0040] Among them, the upper transparent substrate and the lower transparent substrate can be selected from one of PEN, TAC, COP, PET or a composite layer thereof. For a moisture-sensitive system, a low-WVTR barrier coating can be applied to at least one side of the upper transparent substrate and the lower transparent substrate or the outside of the transparent electrode layer, where WVTR is the water vapor transmission rate.

[0041] The transparent electrode layer can be made of ITO, metal mesh, silver nanowire or conductive polymer (e.g. PEDOT:PSS). The electrode material susceptible to corrosion in a humid environment can be further provided with a corrosion protection layer (e.g. SiO2, Al2O3 or organic passivation layer), and the lead / wafer area can be edge passivated to inhibit electrochemical migration. In addition, the transparent electrode layer is coated with at least one of the corrosion protection layer or the lead passivation layer.

[0042] The alignment layer can be made of low-temperature curing polyimide alignment layer or photo-alignment layer; the spacer layer can be made of spherical spacer or cylindrical spacer arranged in the liquid crystal cavity, or micro-pillar array arranged on the surface of the upper transparent substrate and / or the lower transparent substrate. The spacer layer can be used to define the cavity height of the liquid crystal cavity. In addition, the spacer particle size / height is preferably consistent with the target cavity height (e.g. 3-30 μm) to inhibit the wavefront change caused by cavity height drift.

[0043] As shown in Figure 5 The frame sealing layer is used to enclose the liquid crystal cavity and provide long-term sealing. Specifically, the liquid crystal cavity refers to an enclosed space enclosed by the upper transparent substrate, the lower transparent substrate and the frame sealing layer, and filled with liquid crystal. The frame sealing can be made of low-temperature curing adhesive (UV curing or ≤100℃ thermal curing), and a sealing frame adhesive line, a filling port and an exhaust passage are arranged; after filling is completed, a secondary sealing structure is formed at the filling port.

[0044] A reliability enhancement method for low-temperature rollable tunable liquid crystal lens material stack, comprising the following steps, wherein steps S1-S5 are controlled by the controller: S1, constructing a bending or thermal stress model of the multi-layer stack and determining the neutral axis position; S2, selecting CTE matching materials, barrier layer structure and stress release structure according to the model; S3, performing low-temperature packaging and sealing under the condition that the manufacturing temperature is not higher than 100℃; S4, performing accelerated testing of temperature and humidity, bending and voltage life of the product and recording key measurement results; S5, updating the material formula or low-temperature process window according to the failure mechanism and test data and forming a traceability record.

[0045] Second embodiment: This embodiment is mainly about repairable sealing and glue supplementing / secondary sealing, as shown in Figure 5 During mass production, a leak detection station can be performed after filling and initial curing. When the leakage rate is below the upper limit of repair and no irreversible failure such as electrode corrosion / liquid crystal contamination occurs, the following repair strategy can be used: Glue filling ring: The outer surface of the frame seal is cleaned (e.g., by plasma activation or solvent cleaning), a glue filling ring is formed on the outer side and cured at low temperature; the glue filling ring can form a parallel sealing path with the original main glue line, thereby significantly reducing the equivalent leakage rate; Secondary sealing: A secondary sealing cap (partial adhesive / film sealing cap) is formed at the filling port or venting channel, and UV or low-temperature heat curing is used; the secondary sealing cap is preferably made of a material with low volatility, low shrinkage and good adhesion to the substrate / adhesive line; Process control: Rework can be carried out in an inert atmosphere or low dew point environment to avoid moisture introduction; the rework curing energy, time and pressure are also written into the traceability data package as input for subsequent reliability analysis.

[0046] The above-mentioned rework strategy allows for the re-adhesion of the frame sealing layer without removing the transparent electrode layer, thereby restoring the seal, reducing the scrap rate, and improving mass production consistency.

[0047] The third implementation method: This embodiment mainly concerns a stress-relief structure, which is used to reduce warping, delamination, or fogging caused by bending and temperature and humidity cycles, such as... Figure 6 As shown, the stress relief structure can be disposed near the frame seal or in a localized area of ​​the upper or lower transparent substrate to reduce interfacial shear stress concentration. Specifically, the stress relief structure includes a low-modulus compliant zone disposed inside the frame seal, allowing for a gradual strain transition during bending. Optional structures for the compliant zone include: Grooved or corrugated structure: Grooved or corrugated structures are set near the upper transparent substrate, lower transparent substrate or adhesive layer to reduce the equivalent bending stiffness and disperse stress; Gradient adhesive layer: Adhesive layer with modulus or filler concentration gradually changing along the thickness direction to reduce sudden changes in interfacial stress; Local thickening: Thickening the substrate or adding a reinforcing layer in a specific area is used to adjust the position of the neutral axis and reduce the tensile or compressive stress at critical interfaces. Buffer layer: A buffer layer (low modulus organic layer or elastomer) is introduced at the interface between the transparent electrode layer and the upper transparent substrate or the barrier layer and the upper transparent substrate to suppress microcrack propagation and improve peel toughness.

[0048] The aforementioned optional structural features can be used individually or in combination. By designing the interface shear stress peak τ_max below the threshold τ_th (e.g., determined by peel strength and safety factor), the risk of delamination and fogging is reduced.

[0049] Fourth implementation method: This implementation method mainly concerns bending / thermal stress models and material selection, such as Figure 2 and Figure 3To obtain reliable stacking under low-temperature coiling constraint, a simplified laminate model and thermal stress model can be established, in particular: (1) Bending strain: for a stack with total thickness t under bending radius R, the surface strain is approximately ε≈t / (2R). For example, Figure 2 For a multi-layer stack structure, the neutral axis position can be calculated according to the laminate theory: and the distance of each layer from the neutral axis ΔZ i is obtained, where: t is the total thickness of the stack, R is the bending radius; ε is the bending strain; Z0 is the neutral axis position, E i , t i , z i , α i , ν i are the elastic modulus, thickness, geometric center position, CTE and Poisson's ratio of the i-th layer, respectively.

[0050] (2) Thermal stress: for example, Figure 3 Under temperature change ΔT (such as thermal cycling), thermal stress is generated in each layer due to CTE mismatch. The in-layer thermal stress can be estimated by the approximate formula σ i peak, warpage and interfacial shear stress are used as selection criteria for materials and structures.

[0051] (3) Selection strategy: a candidate material library (substrate, electrode, adhesive, barrier layer, buffer layer) is established, and for each candidate combination, σ i peak, τ_max, predicted warpage W_pred and neutral axis offset are calculated; constraints such as σ i <σ_allow, τ_max<τ_th, W_pred<W_th, and bending radius R meet the target coiling diameter; select the combination with the smallest objective function (e.g. J=w1·τ_max+w2·W_pred+w3·ΔCTE) among the schemes that meet the constraints.

[0052] (4) Test calibration: perform bending cycles and thermal cycles on the sample, measure warpage and peel strength; back-substitute the results to calibrate the material parameters and boundary conditions in the model, and improve the prediction accuracy.

[0053] Fifth implementation: This implementation is mainly about barrier layer design and thickness determination. As shown in Figure 4 and Figure 10 , the barrier layer is used to inhibit the intrusion of water vapor and oxygen. A multi-layer barrier structure with inorganic / organic alternating layers can be used, where the inorganic layer provides high barrier, and the organic layer provides crack passivation and stress buffering.

[0054] Diffusion model: Fick's diffusion equation is used The diffusion of water vapor in the barrier layer is estimated, where D is the diffusion coefficient. In one-dimensional approximation, if the equivalent thickness of the barrier layer is L, the upper bound of the inner surface water content as a function of time can be obtained by the boundary conditions (water vapor partial pressure on the outer surface, initial water content on the inner surface).

[0055] (2) Thickness / layer number determination: With the constraint of "the inner surface water content c(t) does not exceed the threshold value c_th within the service life T_use", the minimum L or the minimum dyad layer number N that satisfies the constraint is obtained. In engineering implementation, the WVTR index can also be used equivalently: WVTR_eff≤WVTR_th is required, and N is increased, the density of the inorganic layer is improved, or the interlayer interface is optimized.

[0056] (3) Edge path consideration: In addition to in-plane penetration, there may be an edge penetration path at the edge seal. Local barrier reinforcement (such as edge sealing coating or barrier glue) can be added in the edge area, and edge leakage and in-plane penetration are included in the data package record and failure analysis.

[0057] The sixth implementation mode: This implementation mode is mainly about life extrapolation, as shown in the following formula: Figure 9 To extrapolate from accelerated testing to service life, the Arrhenius model can be used: where T test is the accelerated testing temperature, T use is the service temperature, Ea is the equivalent activation energy (which can be obtained by fitting the life at different temperature points), and k is the Boltzmann constant.

[0058] The specific extrapolation process can include: selecting multiple temperature points for life testing, fitting to obtain Ea; calculating AF at the target service temperature T use ; converting the test life t test to the predicted service life t use ≈t test ·AF. If there is humidity acceleration at the same time, a temperature and humidity coupling model can be introduced or handled with a conservative coefficient, and the extrapolation model version and parameters are recorded in the data package.

[0059] The seventh implementation mode: This implementation mode is mainly about stability criteria and determination process. In order to ensure the stability of optical performance, the haze H and wavefront RMS error W RMS can be set as criteria, and the specific process is as follows: The haze H and wavefront error W RMS are set as stability criteria: |ΔH|<τ_H and |ΔW RMS |<τ_W, where ΔH=H after -H before , ΔW RMS= W RMS，after = W RMS，before .

[0060] (1) Baseline measurement: Measure H before and W RMS，before before test; (2) Post-test measurement: Measure H after and W RMS，before after completing temperature / humidity / bend / voltage life tests, etc.; (3) Difference calculation: AH = H after - H before , AW RMS = W RMS，after - W RMS，before ; (4) Judgment: If |AH| < T_H and |AW RMS | < T_W, then it is judged as pass; otherwise, it is judged as fail, and the cause code is determined in combination with failure appearance, leakage rate and electro-optical response drift; (5) Threshold maintenance: T_H, T_W can be versioned maintained by the controller based on historical yield and failure distribution, and written into traceability log with batch / process window binding, wherein T_H, T_W are stability criterion threshold values respectively.

[0061] Eighth implementation: As Figure 7 this implementation is mainly about the accelerated reliability test process, the controller updates at least one threshold parameter based on the accelerated test or online metrology results, and writes the threshold version, the cause code of the update trigger and the difference before and after the update into a traceability data package or a traceability log.

[0062] The material stack meets the stability criterion of haze and wavefront error when the bend radius R is not less than a preset value, and the preset value is determined according to the target winding diameter and long-term fatigue life.

[0063] The accelerated test can use a multi-dimensional matrix to cover the main stress sources: (a) Temperature and humidity cycle: for example, keep T1 hours at 85°C / 85%RH and cycle N1 times, and measure haze, electro-optical response and leakage rate periodically within the cycle; (b) Bend cycle: perform N2 times of reciprocating bending at a bend radius R (e.g. 20-50 mm), set the bending frequency f, and measure the wavefront and cavity height drift at key cycle numbers (e.g. 10 4 , 10 5 (c) Voltage life: work continuously for T1 hours at the target driving waveform and voltage amplitude, and monitor the changes of transmittance, phase delay and leakage current; ​(d) Combined stress: Bending or voltage driving can be applied simultaneously under temperature and humidity conditions to better simulate actual use conditions.

[0064] By combining temperature and humidity cycles, bending cycles, and voltage life tests, a failure mode matrix is constructed, and the main failure mechanisms and their correlation with material or process parameters are output. For example, Figure 7 , the test output includes at least: H, W RMS , leakage rate L rate , cavity height drift Δh, driving voltage drift ΔV, and electrode resistance change ΔR, etc., and forms a failure mode matrix. By outputting the drift alarm, re-calibration or process rollback is triggered to avoid the accumulation of hidden failures.

[0065] Ninth implementation: As Figure 8 , this implementation mainly describes the failure mechanism, and typical failure mechanisms can include: (1) Water vapor intrusion → electrode corrosion: Water vapor enters along the barrier layer micro-defects or edge path, causing ITO / metal mesh corrosion or electrochemical migration, resulting in resistance rise, open circuit or uneven driving; (2) Water vapor intrusion → liquid crystal contamination / response drift: The increase in water content leads to a decrease in liquid crystal resistivity and a change in dielectric constant, causing driving voltage drift and response time change; (3) Interface delamination / micro-cracks → fogging: Bending and thermal cycling cause interface shear stress accumulation, resulting in micro-cracks and delamination, leading to increased scattering and increased haze; (4) Sealing leakage → bubbles / pollution: Frame sealing or filling port leakage leads to liquid crystal leakage or air / impurities entering, forming bubbles, stripes and local optical distortion; (5) Cavity height drift → wavefront distortion: Spacer compression creep or glue layer shrinkage leads to cavity height change, causing wavefront RMS error to rise.

[0066] For different failure mechanisms, microscopic observation, peeling test, resistance test, and water vapor content estimation can be used to determine the cause code, and the corresponding process / material parameter is updated.

[0067] Tenth implementation: This implementation is mainly about cause code and traceability data package. Cause code refers to the standardized enumeration of failure mode / abnormal source coding, which is used for root cause analysis and process backfill. Traceability data package refers to the structured record of material batch, process window, key metrology, accelerated test results, cause code, and hash / signature information. To support traceable production and closed-loop backfill, it is recommended to establish a traceability data package PRD (Product Reliability Data Package), which can include: (a) Material lots: substrate lots, liquid crystal lots, electrode material lots, glue lots, barrier layer process lots; (b) Process window: curing energy / time / pressure, lamination temperature, ambient dew point, filling pressure and time, etc. (c) Key metrics: cell gap h, wavefront W RMS , haze H, transmittance, driving voltage vs. phase curve, etc. (d) Reliability test: conditions and results of temperature / humidity / bending / voltage life, leakage rate, Ah, AV, etc. (e) Cause code enumeration: for example, RC01 = SEAL LEAK, RC02 = DELAM, RC03 = ITO CORR, RC04 = HAZE, RC05 = CELL GAP DRIFT, RC06 = LC CONTAM, etc. (f) Audit and verification: hash calculation H(data) is performed on the data package and hash_root is recorded; further signature S(hash_root, sk) can be used for cross-organization verification if necessary.

[0068] The controller can version the threshold values (such as τ_H, τ_W, L_rate_th, etc.) based on historical distribution, and write the trigger cause code and update difference when the threshold value is updated, to facilitate review and accountability.

[0069] Among them, the pressure decay or tracer gas method is used to detect the sealing leakage, the sealing leakage is the leakage of the frame sealing layer and its filling port or secondary sealing place, and the leakage rate is written as a rejection index in the traceability data package.

[0070] Eleventh implementation mode: This implementation mode is mainly about iterative optimization closed loop, wherein each iteration at least includes: updating model parameters, generating candidate schemes, trial verification and regression comparison. The iteration can use the following process: (1) Modeling: update the bending / thermal stress model and diffusion model based on the latest material parameters and structure parameters; (2) Screening: generate a set of candidate schemes, calculate the predicted indicators and screen the schemes that meet the constraints; (3) Trial production: trial production of samples within the low-temperature manufacturing window and record the process window, wherein the low-temperature manufacturing window includes three parameter constraints of curing energy, curing time and lamination pressure, and is bound with the traceability data package to support cross-lot consistency control; (4) Testing: according to Figure 7 the test matrix, perform accelerated testing, generate a failure mode matrix and assign a cause code; (5) Recharge: Associate cause code with key parameters, update material recipe, barrier layer count / thickness, compliant zone geometry, and sealing process, where cause code is used to represent at least one failure mode or abnormal source; (6) Audit: Form a traceable data package and perform a hash check to ensure material lot, process window, test results, and cause code consistency and non-tamperability.

[0071] Iterative optimization of material stack CTE match, barrier layer count or thickness, and compliant zone geometry based on accelerated testing and metrology results to reduce warpage, while continuously improving reliability and yield of rollable tunable liquid crystal lens without breaching <100C manufacturing constraints.

[0072] The above description is only the preferred specific implementation of the present application; all the protection scope of the present application is included, any person skilled in the art can make equivalent replacement or change according to the technical scheme and the improvement concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A material stacking structure for a low-temperature adjustable focus liquid crystal lens, characterized in that: It includes an upper transparent substrate, a lower transparent substrate, a transparent electrode layer, an alignment layer, a spacer layer, a liquid crystal layer disposed sequentially on the upper transparent substrate, and a frame sealing layer disposed on the lower transparent substrate; The upper limit of the manufacturing temperature of the material stack is not higher than 100°C. The material stack also includes at least one of a barrier layer and a stress relief structure. The barrier layer is used to reduce water vapor permeability, and the stress relief structure is used to reduce warping, delamination or fogging caused by bending and temperature and humidity cycling.

2. The material stacking structure of the low-temperature adjustable focus liquid crystal lens according to claim 1, characterized in that: Both the upper transparent substrate and the lower transparent substrate are one of PEN, TAC, COP or a composite layer thereof, and at least one side of the upper transparent substrate and the lower transparent substrate is coated with a low WVTR barrier coating.

3. The material stacking structure of the low-temperature adjustable focus liquid crystal lens according to claim 1, characterized in that: The barrier layer is a multi-layered structure with alternating inorganic and organic layers, used to reduce water vapor permeability to below a preset threshold and inhibit oxygen intrusion.

4. The material stacking structure of the low-temperature adjustable focus liquid crystal lens according to claim 1, characterized in that: The frame sealing layer includes a sealing frame adhesive line, a secondary sealing structure, an injection port, and an exhaust channel. The sealing frame adhesive line surrounds the upper and lower transparent substrates and forms a liquid crystal cavity. The injection port and the exhaust channel are located on the sealing frame adhesive line.

5. The material stacking structure of the low-temperature adjustable focus liquid crystal lens according to claim 1, characterized in that: The stress relief structure includes a compliant zone, which is composed of at least one of a gradient adhesive layer, a slotted or corrugated structure, a locally thickened zone, and a buffer layer, such that the peak shear stress at the interface between the frame sealing layer and the substrate is lower than a preset threshold.

6. The material stacking structure of the low-temperature adjustable focus liquid crystal lens according to claim 1, characterized in that: The transparent electrode layer includes at least one of ITO, metal mesh or conductive polymer, and the surface of the transparent electrode layer is coated with at least one of anti-corrosion protective layer or lead passivation layer.

7. The material stacking structure of the low-temperature adjustable focus liquid crystal lens according to claim 1, characterized in that: The spacer layer includes spherical or columnar spacers disposed within the liquid crystal cavity, or an array of micropillars disposed on the surface of the upper transparent substrate and / or the lower transparent substrate, for defining the cavity height of the liquid crystal cavity and suppressing cavity height drift.

8. The material stacking structure of the low-temperature adjustable focus liquid crystal lens according to claim 1, characterized in that: The material stack satisfies the stability criteria for haze and wavefront error when the bending radius R is not less than a preset value. The preset value is determined based on the target winding diameter and long-term fatigue life.

9. The material stacking structure of the low-temperature adjustable focus liquid crystal lens according to claim 1, characterized in that: The material stack also includes one of a surface hard coating and an anti-reflective layer to improve abrasion resistance and transmittance and enhance compatibility with subsequent assembly processes.

10. The material stacking structure of the low-temperature adjustable focus liquid crystal lens according to claim 1, characterized in that: The material stack structure supports repair sealing, that is, when the leak detection determines that it can be repaired, the frame sealing layer can be filled with glue without removing the transparent electrode layer to form a glue ring or to form a secondary cap for the injection port and exhaust channel.

11. The material stacking structure of the low-temperature adjustable focus liquid crystal lens according to claim 1, characterized in that: The cryogenic manufacturing window of the material stack includes three parameters constrained by curing energy, curing time, and bonding pressure, and is bound to a traceability data package to support cross-batch consistency control.

12. A method for enhancing the reliability of a low-temperature rollable and focusable liquid crystal lens material stack, characterized in that, Includes the following steps: S1. Construct a multi-layer stacked bending or thermal stress model and determine the location of the neutral axis; S2. Select CTE matching materials, barrier layer structures, and stress relief structures according to the model; S3. Perform low-temperature encapsulation and sealing under manufacturing temperatures not exceeding 100°C; S4. Conduct accelerated tests on the product for temperature and humidity, bending and voltage life and record key measurement results; S5. Update the material formulation or low-temperature process window based on the failure mechanism and test data, and form a traceability record.

13. The method for enhancing the reliability of the material stack structure of the low-temperature adjustable focus liquid crystal lens according to claim 12, characterized in that: The bending strain of the multilayer stack is approximated by ε≈t / (2R), and the neutral axis position Z0=Σ(E) is calculated according to the laminate theory. i ·t i ·z i ) / Σ(E i ·t i ).

14. The method for enhancing the reliability of the material stack structure of a low-temperature adjustable focus liquid crystal lens according to claim 12, characterized in that: The intralayer thermal stress under thermal cycling is approximated as σ. i ≈Ei(α i -α ref )ΔT / (1-ν i ), and with σ i Peak value, warpage, and interfacial shear stress are used as indicators for material selection and structural screening.

15. The method for enhancing the reliability of the material stack structure of a low-temperature adjustable focus liquid crystal lens according to claim 12, characterized in that: Using the Fick diffusion model Assess moisture intrusion and determine the equivalent thickness L and number of barrier layers based on the constraint that the moisture content c on the inner surface does not exceed the threshold c_th during the service life.

16. The method for enhancing the reliability of the material stack structure of a low-temperature adjustable focus liquid crystal lens according to claim 12, characterized in that: The Arrhenius acceleration factor AF = exp[Ea / k·(1 / T)] is used. use -1 / T test Extrapolate the accelerated test lifetime, where Ea is the equivalent activation energy, k is the Boltzmann constant, and T... test To accelerate the testing temperature, T use For operating temperature.

17. The method for enhancing the reliability of the material stack structure of a low-temperature adjustable focus liquid crystal lens according to claim 12, characterized in that: A failure mode matrix is ​​constructed by combining temperature and humidity cycling, bending cycling, and voltage life tests, and the main failure mechanisms and their correlation with material or process parameters are output.

18. The method for enhancing the reliability of the material stack structure of a low-temperature adjustable focus liquid crystal lens according to claim 12, characterized in that: The interface peel strength or shear strength of the failed samples were measured and calibrated with the bending or thermal stress model to update the adhesive formulation or compliance zone structural parameters.

19. The method for enhancing the reliability of the material stack structure of a low-temperature adjustable focus liquid crystal lens according to claim 12, characterized in that: For the relationship between haze H and wavefront error W RMS Stability criterion: |ΔH| < τ_H and |ΔW RMS |<τ_W, where ΔH=H after -H before ΔW RMS =W RMS，after -W RMS，before .

20. The method for enhancing the reliability of the material stack structure of a low-temperature adjustable focus liquid crystal lens according to claim 12, characterized in that: The sealing leak is detected by pressure decay or tracer gas method. The sealing leak is the leakage of the frame sealing layer and its injection port or secondary seal. The leakage rate is written into the traceability data packet as the rejection index.

21. The method for enhancing the reliability of the material stack structure of a low-temperature adjustable focus liquid crystal lens according to claim 12, characterized in that: Based on the results of accelerated testing and metrology, the CTE matching of the material stack, the number or thickness of the barrier layer, and the geometry of the compliant region are iteratively optimized to reduce warpage. Each iteration includes at least: updating model parameters, generating candidate schemes, prototyping verification, and regression comparison.

22. The method for enhancing the reliability of the material stack structure of a low-temperature adjustable focus liquid crystal lens according to claim 12, characterized in that: Statistical process control is performed on the cryogenic process window to output drift alarms and trigger recalibration or process rollback in order to avoid the accumulation of latent failures.

23. The method for enhancing the reliability of the material stack structure of a low-temperature adjustable focus liquid crystal lens according to claim 12, characterized in that: Reliability test data is correlated with cause codes to support root cause analysis and manufacturing parameters are fed back in, the cause codes being used to characterize at least one failure mode or source of anomaly.

24. The method for enhancing the reliability of the material stack structure of a low-temperature adjustable focus liquid crystal lens according to claim 23, characterized in that: Hash verification is performed on traceability data packets and verifiable audit records are generated to ensure the immutable association between material batches, process windows, test results and cause codes.

25. The method for enhancing the reliability of the material stack structure of a low-temperature adjustable focus liquid crystal lens according to claim 12, characterized in that: Steps S1-S5 are all controlled by the controller. The controller updates at least one threshold parameter based on the accelerated test or online measurement results, and writes the threshold version, the reason code for the update trigger, and the difference before and after the update into the traceability data packet or traceability log.

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