| HS Code | 850552 |
| Thickness | 0.45 mm |
| Density | 0.94 g/cm³ |
| Melt Flow Rate | 25 g/10 min |
| Light Transmittance | ≥91% |
| Gel Content | ≥75% |
| Adhesion To Glass | ≥60 N/cm |
| Adhesion To Backsheet | ≥40 N/cm |
| Volatile Content | ≤0.5% |
| Moisture Content | ≤0.1% |
| Shrinkage | ≤3% MD, ≤2% TD |
| Tensile Strength | ≥18 MPa |
| Elongation At Break | ≥550% |
| Dielectric Constant | 2.8 |
| Volume Resistivity | >1×10^15 Ω·cm |
| Dielectric Breakdown Voltage | >15 kV/mm |
| Uv Cut Off Wavelength | <360 nm |
| Lamination Temperature | 145-150 °C |
| Lamination Time | 10-15 min |
| Shelf Life | 6 months at ≤30 °C |
| Storage Conditions | Cool, dry, ≤60% RH, avoid moisture and UV |
As an accredited STRATO SOLAR PV encapsulant EVA Film factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
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During lamination of a TOPCon or PERC string on 3.2 mm low-iron tempered glass with a 1.6 mm fluoropolymer-coated backsheet, the critical process variable is not merely plate temperature but the concurrent development of peroxide crosslinking, silane glass adhesion, and backsheet thermal relaxation. The STRATO SOLAR PV encapsulant EVA film is typically processed as a fast-cure grade containing vinyl acetate units in the 28–33 wt% range, a peroxide initiator, silane coupling agent, and UV stabilizer package; lamination on a flat-bed vacuum laminator with a 1200 mm × 2400 mm pin-type heating platen requires a plate setpoint of 150–152 °C, a 5–6 min vacuum hold, and a 6–8 min press at 0.08–0.10 MPa. The gel content of the cured encapsulant, measured by xylene extraction according to ASTM D2765-16, should reach 75–85%; values below 70% correlate with reduced cohesive strength, increased acetic acid release from residual vinyl acetate, and edge creep in 85 °C/85% RH damp-heat exposure. Crosslinking initiates when the EVA reaches 135–140 °C, but the edge of a large laminate can remain below this threshold if the heating platen center-to-edge differential exceeds 5 °C, producing a measurable gel-content gradient. Production line audits have identified edge zones with gel content 5–10 percentage points lower than the center when the vacuum membrane draft pulls cooler air across a partially cured film. Adhesion to ARC glass is facilitated by an organosilane primer in the EVA; peel values are commonly assessed against internal acceptance limits after lamination and after 1000 h damp-heat IEC 61215-1:2021 exposure, with failure typically defined as glass-side delamination or bubble area above 5% of the module surface. For TOPCon cell metallization, the front Ag/Al paste and rear poly-Si contact are not directly attacked by the EVA at peak temperatures, but acidic decomposition products from excess unreacted vinyl acetate can migrate through microcracks in the backside passivation stack under negative system voltage, contributing to potential-induced degradation. The cure window is therefore bounded on the low side by incomplete peroxide decomposition and on the high side by backsheet shrinkage, cell displacement, and thermal stress in the solder bonds; the acceptable envelope is generally quoted as 145–155 °C plate temperature with total dwell time 8–12 min for 3.2 mm front glass. The final module is qualified by IEC 61215-1:2021, IEC 61730-2:2023, and UL 1703 where applicable; the encapsulant contributes to insulation, mechanical load, hail impact, and wet leakage current compliance. Amine-functional adhesion promoters or release agents that deplete free radicals must be excluded from the laminator chamber because they depress gel content and cause measurable post-lamination haze, quantified by ASTM D1003-21 above 1.5% for encapsulated textured glass.
Structurally, glass-glass bifacial configurations using 2.0 mm heat-strengthened glass on both faces convert the encapsulant film into an interlayer that must compensate for low post-breakage structural redundancy and edge stress concentration. The absence of a polymer backsheet places the EVA between two rigid, low-thermal-expansion substrates; during lamination the plate setpoint is usually reduced to 145–150 °C because the double-glass stack retains heat more effectively and slows post-press cooling. A vacuum/press sequence of 4 min vacuum followed by 10–15 min at 0.07–0.09 MPa is typical, after which the hot laminate is transferred to a cooling press with flatness tolerance ≤ 0.05 mm/m to avoid bow. Cured gel content by ASTM D2765-16 should be 80–90%, and residual interfacial stress must be checked by ultrasonic scanning and dark-field edge inspection before framing. In dual-glass modules, the EVA’s electrical volume resistivity, measured by ASTM D257-14, is held above 1×10¹⁴ Ω·cm to minimize leakage current pathways across the glass/EVA interface under system voltages up to 1500 V. A specific failure signature observed on production lines is post-lamination edge squeeze-out, where molten EVA extruding beyond the glass edge forms a hydrolytically weak lip; in modules without an edge seal, this lip absorbs moisture under 85 °C/85% RH damp-heat and creates a corroded ribbon zone at the laminate perimeter. To limit this, framing systems use desiccant-filled aluminum channels and structural silicone, while frameless double-glass designs often specify polyisobutylene edge tape of 10–15 mm width. The EVA must also tolerate rear-side irradiance of 100–200 W/m² in bifacial operation; the UV-stabilizer package is selected so that yellowness index by ASTM E313-20 after 3000 h of damp heat plus UV does not exceed ΔYI 2. The final glass-glass module is qualified under IEC 61215-1:2021 and IEC 61730:2023, with bifacial rear-side power rating measured according to IEC TS 60904-1-2:2019; the EVA film affects rear-side transmittance and total internal reflection, so a high-transparency grade with haze <1.0% by ASTM D1003-21 is preferred for the rear cell region. For ground-mount and agrivoltaic sites with long wind-driven rain exposure, the formulation should avoid excess vinyl acetate that can hydrolyze to acetic acid; published data for the specific corrosion threshold is limited, but utility-scale sellers increasingly specify glass-glass construction because the edge ingression path is physically shorter than in glass-backsheet stacks.
Deposition of CdTe or CIGS absorber layers on soda-lime substrates leaves back contact stacks that are temperature-sensitive and electrochemically reactive; a standard EVA cure at 150 °C can diffuse indium, copper, or molybdenum species along interfacial grain boundaries and increase series resistance. Thin-film laminates therefore use a lower-temperature EVA grade or a reduced-dwell program at 130–140 °C, extending total cycle time to 12–18 min while maintaining a target gel content of 70–80% by ASTM D2765-16. The laminator is typically a vacuum-type unit with flexible silicone diaphragm; because thin-film cells cover the entire glass surface, no cell-string gaps exist to form melt-flow channels, so the EVA must wet a monolithic semiconductor stack without producing excessive transverse flow that dislocates the absorber edge. The film’s sodium- and acetate-leachable fractions must be kept low: sodium from the front glass substrate is known to degrade CdTe and CIGS device performance, and EVA-derived acetic acid can attack the transparent conductive oxide. Formulations for this application use VA contents at the lower end of the solar range, typically 28–30 wt%, and crosslinking is designed to approach complete vinyl acetate conversion to reduce hydrolysis sites. Volume resistivity measured by ASTM D257-14 is maintained above 1×10¹⁴ Ω·cm, and wet leakage current after immersion is assessed as part of IEC 61730-2:2023. Thin-film modules frequently use frameless glass-glass construction with an edge seal of polyisobutylene or butyl rubber, because the EVA is not a primary moisture barrier; its water vapor transmission rate is roughly one order of magnitude higher than that of the glass and edge seal, so the edge seal must bear the dominant humidity exclusion function. Final product qualification relies on IEC 61215-1:2021 and IEC 61730, plus IEC 61701:2020 for salt mist when modules are deployed in coastal or farming environments. The accepted operational boundary is that the EVA should remain below 140 °C for CdTe back-contact stability; above this, field-proven failure accelerations include back-contact peel and transparent conductive oxide cracking, though module-level data for specific CIGS stacks are limited. The manufacturer’s batch release should include melt flow rate by ISO 1133-1:2022, typically 20–30 g/10 min at 190 °C/2.16 kg, as a check against excessive exudation into the edge zone.
| Application segment | Typical stack | Plate temperature | Dwell/pressure | Post-cure gel target | Dominant process risk |
|---|---|---|---|---|---|
| c-Si TOPCon/PERC | 3.2 mm glass/EVA/cell matrix/EVA/backsheet | 150–152 °C | 6–8 min at 0.08–0.10 MPa | 75–85% | Edge gel lag and backsheet shrinkage |
| Bifacial glass-glass | 2.0 mm glass/EVA/bifacial cell/EVA/2.0 mm glass | 145–150 °C | 10–15 min at 0.07–0.09 MPa | 80–90% | Edge squeeze-out and bow |
| Thin-film CdTe/CIGS | glass/EVA/monolithic cell/EVA/glass or barrier film | 130–140 °C | 12–18 min at 0.06–0.08 MPa | 70–80% | Back-contact degradation above 140 °C |
| Overhead BIPV | glass/EVA/glass or panel | 140–150 °C | 20–30 min at 0.10–0.12 MPa | 75–85% | Over-curing and residual bubble |
| Floating PV | glass/EVA/cell/EVA/glass with PIB edge | 145–150 °C | 10–15 min at 0.08–0.10 MPa | 85–95% | Incomplete edge crosslink and leakage current |
| Vehicle-integrated roof | curved glass/EVA/cell/EVA/polycarbonate | 135–145 °C | 8–10 min at 0.05–0.07 MPa | 70–80% | Cell drift and optical distortion |
| Flexible metal roof | ETFE/EVA/cell/EVA/stainless or FRP | 125–135 °C | 10–14 min at 0.04–0.06 MPa | 70–80% | CTE mismatch and wrinkling |
Overhead BIPV modules laminated with EVA are governed by building safety glazing requirements in addition to PV qualification, so the encapsulant must act as a structural interlayer after breakage. Unlike a standard field module, a roof-integrated or façade-integrated unit is subject to EN 12600 pendulum impact, EN ISO 12543-2 adhesion and durability requirements, and EN 50583-1/-2 classification for building-integrated systems; the EVA interlayer must retain glass fragments after impact and remain bonded through thermal cycling between -40 °C and 85 °C. Lamination for BIPV frequently uses a two-chamber oil-heated laminator or autoclave because the glass stack may include a thick, heat-strengthened outer pane, an inner polymer film, and rear glass or honeycomb panel. The cure profile is 140–150 °C for 20–30 min, with pressing pressure increased in stages to 0.10–0.12 MPa to ensure bubble-free coverage across large formats without glass bow. Gel content after cure by ASTM D2765-16 should be 75–85%, and the laminated composite’s flexural stiffness and post-breakage retention are verified by measured deflection under an imposed point load. In overhead applications, haze and yellowing are visual acceptance issues: initial luminous transmittance should exceed 91% and haze by ASTM D1003-21 should remain below 1.5% after 1000 h of 85 °C/85% RH; yellowing index by ASTM E313-20 should shift less than 2 units after 2000 h UV exposure. Fire classification of the laminated glass assembly under EN 13501-1 is not determined by the EVA alone, but the film must be disclosed as organic content in the reaction-to-fire file, and certain building codes restrict combustible interlayer mass per square meter. A practical process incompatibility occurs when BIPV integrators re-melt partially cured EVA in a second lamination cycle at 150 °C for bonding to building components; this can over-crosslink the film to gel content above 95%, causing brittleness, lowered peel adhesion, and micro-void formation. Therefore the fastener or framing interface should be completed during the primary lamination cycle or by a cold-bond adhesive, not by reheating the encapsulant. The final BIPV product may carry fire, safety glazing, PV safety, and wind load ratings simultaneously; the EVA contributes to IEC 61215-1:2021 mechanical load resistance and IEC 61730-2:2023 electrical insulation, but building code compliance is certified at the assembly level.
On freshwater and nearshore marine reservoirs, module enclosures continuously draw high humidity and chloride aerosol across the laminate edge, shifting the encapsulant requirement from optical permanence to electrochemical isolation. Floating PV arrays expose the EVA to condensation, mechanical wave flexure, and salt spray; the module must pass IEC 61701:2020 salt mist and IEC 60068-2-52 cycling salt mist, while the encapsulant must suppress leakage current and protect solder ribbon and cell metallization. For this application, the chosen EVA film should be a low-free-acetate, high-gel-content grade; post-cure gel content by ASTM D2765-16 is typically specified above 85% and sometimes 90%, because residual unreacted vinyl acetate accelerates acetic acid formation at the glass/EVA interface under continuous humidity. The lamination cycle is similar to glass-glass bifacial: 145–150 °C plate temperature, 10–15 min dwell, and 0.08–0.10 MPa pressure; after cooling, edge squeeze-out must be trimmed or fully encapsulated by polyisobutylene before framing. Wet leakage current is measured after immersion per IEC 61730-2:2023 at 500 V or system maximum voltage; field experience shows that defective edge gel content below 75% can elevate wet leakage current beyond the acceptable module limit, especially when the junction box potting is incomplete. The EVA must also maintain adhesion to ARC glass under long-term salt spray; adhesion failure at the edge is observed as white bloom and glass-side interlayer separation after 3000 h of salt mist exposure. Framed floating modules often use double-layer edge seal: a butyl primary seal followed by a structural silicone secondary seal; the EVA is not interchangeable with this seal system and must be fully cured before the frame is applied. The final system is qualified to IEC 61215-1:2021, IEC 61730:2023, and IEC 61701:2020, with additional corrosion testing on connectors and ribbons because the encapsulant is one part of a multi-material electrochemical chain. A known operational boundary is that EVA with high vinyl acetate content above 33 wt% tends to produce more mobile acetate species in hot, humid environments; therefore solar grades used in floating modules are frequently specified at the lower VA limit to restrict hydrolysis kinetics. Published data for long-term floating performance of EVA versus polyolefin encapsulants is limited, but utility owners increasingly require monitoring of cell-to-frame leakage current and electroluminescence imaging at annual intervals.
Vehicle-integrated photovoltaic modules use non-planar substrates such as deep-drawn polycarbonate, curved tempered glass, or painted metal roof panels; the EVA encapsulant must fill the curvature without cell misalignment, air pockets, or residual melt-flow orientation that produces optical distortion. The lamination equipment for automotive canopy and roof modules is often a short-cycle diaphragm vacuum press with heated aluminum tooling shaped to the substrate, rather than a flat-bed solar laminator. Because the substrate curvature varies, the film is pre-tacked at 80–90 °C before the full cure step at 135–145 °C, with dwell limited to 8–10 min to protect polycarbonate from prolonged heat. The target gel content by ASTM D2765-16 is 70–80%, balancing sufficient crosslinking against the lower thermal stability of the polymer backsheet. Automotive environmental qualification follows ISO 16750-4:2023 for thermal cycling from -40 °C to 85 °C, and the laminate is also screened under IEC 61215-1:2021 where applicable. The EVA must maintain adhesion to curved glass and polycarbonate under vibration; peel testing often follows ASTM D903-98 or a custom 90° peel fixture because no single PV standard fully captures curved adhesive peel. A field-observed failure in automotive lamination is cell cracking when the melted EVA carries cells along flow lines; the cure pressure is therefore reduced to 0.05–0.07 MPa compared with flat glass modules to control cell drift. Optical quality is measured by ASTM D1003-21 haze on a flat witness coupon and by visual inspection with a zebra-board or fringing pattern on curved surfaces; haze must remain below 1.0% in the viewing zone. The final roof module must also comply with automotive safety standards for head impact and flammability, but those are assembly-level requirements; the EVA contributes as an interlayer that retains glass fragments after impact. Published data for EVA adhesion to polycarbonate in deep-drawn configurations is limited, so production trials should include damp-heat exposure at 85 °C/85% RH and thermal shock cycling before the full qualification batch is released. Amine-functional plasticizers and moisture-reacting polyurethane residues on polycarbonate surfaces must be eliminated prior to EVA placement, because they consume peroxide radicals and reduce gel content at the interface, producing bubbles and delamination after 1000 h of damp heat.
Because thin stainless steel and fiber-reinforced polymer backsheets impose unequal thermal expansion across the laminate stack, cure schedules for lightweight flexible modules shift toward lower peak temperatures and longer dwell to avoid wrinkling and edge curl. Flexible and semi-flexible modules for standing-seam metal roofs, truck trailer roofs, and portable off-grid arrays rely on EVA to bond an ETFE or fluoropolymer front film to a thin metal or FRP backsheet; the stack is laminated in a vacuum press or a roll-to-roll vacuum laminator with flexible tooling. Non-planar thermal expansion can exceed 5 mm/m during cooling if the EVA crystallizes while the backsheet is still contracting, so the cooling stage must be controlled at 5–10 °C/min and the laminate restrained until the platen temperature falls below 60 °C. The cure profile is typically 125–135 °C for 10–14 min, with gel content by ASTM D2765-16 of 70–80%; higher gel content above 85% can reduce conformability and lead to interlayer cracking during repeated bending. Because there is no front glass, the EVA is directly exposed to moisture ingress through the thin front film, so the grade must combine low free acetate with high adhesion to ETFE; fluoropolymer surfaces require plasma or corona pre-treatment to reach 35–50 dyn/cm wetting tension, otherwise peel adhesion after damp heat drops below the usual internal acceptance boundary. Electrical insulation is assessed by ASTM D257-14, and the flexible module is qualified under IEC 61215-1:2021 with additional flexure cycles specified by the integrator because no single standard fully covers all portable and vehicle-mount stress modes. The EVA layer also functions as the primary dielectric between the cell circuit and the conductive metal roof; therefore any pinholing or thickness variation below 150 μm becomes a wet insulation failure site. Published data for EVA on stainless steel and FRP in roll-to-roll lamination is limited, and outdoor validation campaigns often show that the dominant failure mode is not cell degradation but edge delamination at the front film/EVA interface under high UV albedo. For that reason, module designers specify an edge sealing tape or heat-sealed film overlap around the perimeter, and the encapsulant is not expected to serve as the sole environmental barrier in continuous outdoor service.
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STRATO SOLAR PV encapsulant EVA film is a peroxide-cured ethylene-vinyl acetate sheet supplied for crystalline silicon photovoltaic module lamination. The product is available in nominal thicknesses of 0.45 mm, 0.50 mm, 0.60 mm, and 0.80 mm, in roll widths of 1,000 mm, 1,100 mm, and 1,300 mm, and in roll lengths of 150 m and 200 m. Model designations are divided by cure-rate class—standard cure, fast cure, and ultra-fast cure—and exact alphanumeric codes should be confirmed against the current datasheet. The film is positioned between the front glass and the cell string and between the cell string and the backsheet. It is intended for crystalline silicon modules with glass-backsheet and glass-glass stacks, including bifacial and building-integrated configurations. After vacuum lamination, it provides optical coupling, mechanical load transfer, and electrical isolation in module qualification sequences such as IEC 61215-2 and IEC 61730-2.
For void-free lamination, the uncured film must flow around cell edges and interconnect ribbons before crosslinking develops. Melt flow rate is typically 20 g/10 min to 40 g/10 min at 190 °C and 2.16 kg per ISO 1133-1:2022. The peroxide initiator is dispersed in the EVA matrix; one-hour half-life temperature is near 135 °C, and one-minute half-life is near 165 °C. Because the decomposition rate rises steeply between these temperatures, the practical lamination window for standard-cure grades is 145 °C to 155 °C at the cell surface. A deviation beyond ±5 °C can produce undercure at the module perimeter or premature crosslinking before complete void elimination in the center.
Gel fraction after lamination is measured with ASTM D2765-16. A production-ready laminate typically exhibits 75% to 90% gel fraction. Gel fraction below 70% correlates with thermoplastic creep, high thermal shrinkage, and loss of adhesion after damp heat. Gel fraction above 95% can increase embrittlement and edge cracking under mechanical load. On multi-chamber laminators, the cure station residence time is rate-limiting for standard-cure film, while fast-cure and ultra-fast-cure grades can shift the bottleneck to the cooling or handling stations. Platen temperature non-uniformity should be controlled to ±2 °C; bubble clusters at cell edges are commonly observed when the ramp rate exceeds 3 °C/min.
For air evacuation during vacuum lamination, the film is supplied with a controlled embossed surface on one or both sides. Embossing depth is typically 20 µm to 60 µm; the pattern collapses during lamination and does not contribute to residual haze. Thickness tolerance is maintained by beta gauge feedback on the casting line at ±10% of nominal. Roll winding tension is set to avoid blocking, typically 20 N/m to 40 N/m of roll width.
Unopened rolls should remain in their moisture-barrier packaging at 15 °C to 25 °C and below 60% relative humidity. If a roll equilibrates above 60% RH for more than 24 h, pre-drying is required; the corrective step is 8 h to 12 h at 40 °C in a desiccated cabinet. Contact with amine-based additives, certain organometallic colorants, and strongly acidic substrates should be prevented because these species can deactivate the peroxide or promote premature crosslinking. Shelf life is normally 6 months from date of manufacture in the original sealed packaging.
Adhesion to glass and backsheet is evaluated after lamination and after exposure at 85 °C and 85% relative humidity for 1,000 h to 2,000 h according to IEC 61215-2. Peel tests are typically performed at 180° peel angle and 100 mm/min jaw separation speed. EVA encapsulants of this class are generally specified above 60 N/cm to glass and above 40 N/cm to polyester-based backsheets before aging. Published data for the exact STRATO SOLAR formulation are limited; current datasheet values should be used for lot acceptance. The silane coupling agent reacts with glass hydroxyl groups during lamination, and incomplete reaction due to low cure is detected as interfacial failure in aged peel specimens.
Mechanical properties of the cured film are measured by ASTM D882-18. Typical tensile strength after crosslinking ranges from 10 MPa to 20 MPa, and elongation at break from 400% to 600%. These values reflect the transition from thermoplastic melt to elastomeric network. Uncured film is weaker and can stretch during roll threading on automated stringer lines; therefore, film tension should be controlled below the yield point of the uncured material and indexed to roll diameter.
Laminated optical transmittance is normally above 91% in the 400 nm to 1,100 nm wavelength band when measured by ASTM D1003-21, with haze below 2%. Yellowness index change after 1,000 h of damp heat or UV preconditioning is specified below 2 units under ASTM E313-20. The UV absorber package is selected to protect the encapsulant and cell interconnect without suppressing blue response in crystalline silicon cells. The cured film also functions as a dielectric; volume resistivity is specified above 1×1014 Ω·cm at 25 °C according to ASTM D257-14.
For medium-voltage building-integrated arrays, the encapsulant must also limit surface leakage currents. In these applications, lamination voids and bubbles act as partial discharge sites; film surface quality is therefore monitored by automated optical inspection for gels, fisheyes, and thickness bands before layup. The film is processed at casting speeds comparable to 20 m/min to 40 m/min with optical defect detection at a minimum resolution of 0.2 mm.
System voltages above 1,000 V increase the electric field across the encapsulant and backsheet. Volume resistivity and its retention under humidity become dominant selection criteria. The EVA film is formulated to maintain volume resistivity above 1×1014 Ω·cm after lamination without a high-voltage post-cure. Potential-induced degradation testing according to IEC 62804-1 screens module stacks at ±1,500 V, 85 °C, and 85% RH for 96 h. EVA with insufficient bulk resistivity or excessive sodium ion mobility can show power loss at the negative pole. The low-degradation formulation approach uses additives that reduce free acid and mobile ion content; the specific additive package is proprietary. For modules with extended damp-heat requirements above 2,000 h, POE-based encapsulants may be preferred if edge corrosion or acetic acid generation is a concern.
The main alternative encapsulant chemistries are polyolefin elastomer, polyvinyl butyral, and ionomer sheets. STRATO SOLAR EVA Film differs from POE in processability: uncured EVA has lower melt viscosity and develops adhesion to glass at lower lamination temperatures; POE generally has lower moisture vapor transmission and higher volume resistivity, which favors glass-glass and bifacial configurations. The EVA formulation compensates through silane adhesion promoters and a low-acid-generation peroxide package, but POE may be preferred when damp-heat exposure exceeds 2,000 h or when sodium ion migration is the dominant degradation mechanism.
PVB is not a direct substitute in photovoltaic lamination because PVB requires higher processing pressure and has greater moisture sensitivity. Its use is concentrated in architectural glass and thin-film modules where edge adhesion and shear modulus are more important. Ionomer sheets offer higher stiffness and impact resistance but require higher lamination temperature and exhibit lower melt flow. EVA remains the lowest-cost encapsulant with a broad lamination window and is suitable for standard glass-backsheet modules, while POE-based stacks are generally preferred for bifacial and high-humidity applications.
Within EVA films, STRATO SOLAR EVA Film is differentiated by cure speed, shrinkage, and adhesion retention after damp heat. The fast-cure and ultra-fast-cure grades reduce cycle time to 6 min to 10 min at 150 °C in low-thermal-mass single-chamber laminators, whereas standard-cure EVA may require 12 min to 18 min. Shrinkage after 30 min at 150 °C is typically below 4% in the machine direction and 2% in the transverse direction when measured by ASTM D2732-20.
Dimensional stability is relevant when the film is used with thin glass or large-format modules. Shrinkage above 4% in the machine direction can pull cell strings out of alignment during lamination, particularly in modules larger than 2 m². The film is annealed during manufacture to reduce frozen-in stress; residual shrinkage is measured after free-standing exposure at 150 °C for 30 min by ASTM D2732-20. In roll-fed stringer lines, edge curling should be monitored because it can cause double-sheet feeding or misalignment at the layup station.
| Property | Test Method | Typical Range | Unit |
|---|---|---|---|
| Nominal thickness | Beta gauge / micrometer | 0.45–0.80 | mm |
| Gel fraction after lamination | ASTM D2765-16 | 75–90 | % |
| Tensile strength, cured film | ASTM D882-18 | 10–20 | MPa |
| Elongation at break, cured film | ASTM D882-18 | 400–600 | % |
| Laminated transmittance, 400–1,100 nm | ASTM D1003-21 | >91 | % |
| Haze after lamination | ASTM D1003-21 | <2 | % |
| Volume resistivity at 25 °C | ASTM D257-14 | >1×1014 | Ω·cm |
| Shrinkage at 150 °C, machine direction | ASTM D2732-20 | <4 | % |
| Shrinkage at 150 °C, transverse direction | ASTM D2732-20 | <2 | % |
| Requirement | Standard or Test Method | Acceptance Criterion |
|---|---|---|
| Module qualification | IEC 61215-2 | No visual defect; power loss <5% after damp heat, thermal cycling, humidity freeze |
| Module safety | IEC 61730-2 | Insulation resistance, dielectric withstand, and creepage requirements |
| PID resistance | IEC 62804-1 | Power loss <5% at ±1,500 V, 85 °C/85% RH, 96 h |
| Gel fraction | ASTM D2765-16 | 75%–90% |
| Optical retention | ASTM E313-20 | ΔYI <2 |
| Restricted substances | RoHS Directive 2011/65/EU | Below threshold concentrations |
| SVHC declaration | REACH Regulation (EC) 1907/2006 | Supplier declaration on current Candidate List |
For the ultra-fast-cure grade, a representative single-chamber lamination sequence is vacuum dwell at 145 °C for 3 min, membrane press at 80 kPa for 6 min, and cooling to 40 °C before unloading. This sequence is a process starting point; exact parameters must be optimized for module size, glass thickness, and laminator thermal mass. The film should be qualified in the complete module stack, including backsheet and glass, before full production release.
