Realize transparent alumina on vacuum winding evaporation coating machine（Al?O?）The deposition of thin films requires addressing core issues such as high-temperature evaporation, oxidation reaction control, and winding uniformity. The following are specific implementation plans and key technical points:

1. Process scheme design

(1)Selection of evaporation source

Final choice:
Using electron beam evaporation+Plasma assisted reactive deposition（PAR）At the same time as evaporating aluminum, oxygen is introduced and excited by plasma（RF 13.56MHz）Promote the generation of alumina.

(2)Coating system configuration

2. Optimization of key process parameters

(1)Evaporation control

Aluminum evaporation rate:0.5-2 nm/s(Through electron beam current)6-10kV/100-300mAAdjustment)

Oxygen partial pressure:2×10? 2 - 5×10? 2 Pa(Too high leads to a decrease in rate, too low leads to insufficient oxidation)

Substrate temperature:80-150℃ (flexible polymer substrate required)<120℃）

(2)Plasma assisted

(3)Winding system parameters

Roll speed:0.1-1 m/min(Corresponding to film thickness)50-500nm）

Tension control:10-20N(Avoid substrate deformation)

Cooling roller temperature:15-25℃ (to prevent heat accumulation)

3. Film performance regulation

(1)Optical performance optimization

Refractive index control:1.62-1.67(Adjusted by oxygen aluminum ratio)

Method: Online optical monitoring（550nmTransmittance at different locations>85%）

Extinction coefficient:<0.001(Avoid residual aluminum metal)

(2)Mechanical performance enhancement

Hardness:>8 GPa(achieved through ion beam assisted deposition)

Adhesion: ThroughArPlasma pretreatment（50W, 60s）MakePETSurface energy of substrate>50mN/m

(3)Improved barrier performance

Water vapor permeability（WVTR）：<10? 3 g/m2/day(requires film thickness)>100nmAnd without pinholes)

Testing method: Calcium testing method（85℃/85%RH）

4. Typical application cases

(1)Flexible electronic packaging

Requirement: InPETSubstrate (thickness)125μm）Top plating300nm Al? O?Barrier layer

workmanship

Electron beam evaporation of aluminum (rate)1.2nm/s）

Oxygen flow rate20sccm，RFpower200W

Roll speed0.3m/min, tension15N

Result:

Visible Light Transmittance88%

WVTR 5×10?? g/m2/day

(2)photovoltaic backsheet

Challenge: Avoid film cracking during the winding process

Solution:

Adopting segmented deposition (plating per cycle)50nmInterval cooling10s）

addSiO?Transition layer (thickness)10nm）Reduce internal stress

5. Common Problems and Countermeasures

6. Technical upgrade direction

(1)Multi evaporation source synergy

Al+MgCo evaporation: PreparationMgdopingAl?O?Enhance dielectric performance

Dynamic baffle technology: achieving transverse film thickness gradient (for optical filters)

(2)intelligent control

Machine learning optimization:

Input: real-time data of evaporation rate, oxygen partial pressure, and transmittance

Output: Automatic adjustmentRFPower ofPIDparameter

Digital twin system:ANSYSSimulate the heat during the winding process-Force coupling effect

(3)Environmental protection technology

Aluminum recycling system: Condenser plate collects non deposited aluminum, recovery rate>90%

Low energy design: using pulsed plasma (duty cycle)30%）Reduce40%energy consumption

Conclusion:

To achieve high-quality transparent alumina film on a vacuum wound evaporation coating machine, it is necessary to focus on controlling the adequacy of oxidation reaction and the dynamic stability of winding. By combining electron beam evaporation with plasma assistance, thin films with high transmittance and excellent barrier properties can be obtained on flexible substrates. Future development directions include:
① Large area uniformity improvement (width)>2m）；
② Ultra-thin continuous deposition（<10nmNo pinholes);
③ Compared to other functional film layers (such asSiO?TheITO）Online composite sedimentation.