| HS Code | 686181 |
| Brand | FIRST |
| Productname | Super Fast-Cure EVA Film SU406 |
| Model | SU406 |
| Type | Fast-cure EVA film |
| Material | Ethylene-vinyl acetate copolymer |
| Thickness | 0.45 mm |
| Width | 1000-2200 mm |
| Density | 0.95 g/cm³ |
| Meltflowrate | 25 g/10 min |
| Meltingpoint | 68 °C |
| Softeningpoint | 60 °C |
| Lighttransmittance | ≥91% |
| Uvtransmittance | ≥85% (300-380 nm) |
| Adhesiontoglass | ≥80 N/cm |
| Adhesiontobacksheet | ≥50 N/cm |
| Gelcontent | ≥75% |
| Thermalshrinkage | ≤3% (MD/TD) |
| Volumeresistivity | ≥1.0×10^15 Ω·cm |
| Dielectricstrength | ≥30 kV/mm |
| Waterabsorption | ≤0.1% |
| Curingtemperature | 145-150 °C |
| Curingtime | 8-12 min |
| Storagetemperature | 5-30 °C |
| Shelflife | 12 months |
As an accredited FIRST Super Fast-Cure EVA Film Su406 (UV transmittance) factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
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Module laminators processing glass-backsheet crystalline silicon stacks place Su406 in a front and rear encapsulant position before the vacuum lamination diaphragm closes. In this configuration the film is not diluted or compounded on the module line, but the area-based formulation addition ratio is the controlling parameter: one 0.45 mm front ply and one 0.45 mm rear ply, trimmed to a perimeter allowance of 5–8 mm beyond the cell string, contribute a total encapsulant mass of 850–900 g/m² when calculated at an EVA density of 0.95 g/cm³. Qualification documentation for this downstream use is anchored to IEC 61215-1:2021 for design qualification, IEC 61215-2:2021 for test procedures, IEC 61730-1:2016 and IEC 61730-2:2016 for safety construction and testing, and UL 61730-1 where North American listing is required. Optical acceptance is verified by IEC 62788-1-4:2020 for encapsulant transmittance measurement and by ASTM E903-20 for spectral transmittance with an integrating sphere; the UV transmittance window in the 320–400 nm band is checked before lamination because glass-backsheet PERC and TOPCon lines use the measured transmission to confirm that the encapsulant is not retaining photons that belong to the short-wavelength response of the cell. The downstream production process is a vacuum-bag thermal cure on a triple-chamber hydraulic laminator with a 3.2 m bed, preheated glass at 65–75 °C, and a two-stage vacuum sequence that reaches -0.10 MPa before diaphragm pressure is applied at 0.06–0.08 MPa. Cure is held at 145–150 °C for 8–10 min after the module centre reaches the lamination set point, and gel content is verified between 75% and 85% by xylene extraction according to ASTM D2765-16. Lines that store film above 60% RH require re-drying at 65 ±5 °C for 12 h before layup to prevent residual moisture from hydrolyzing silane coupling agents and lowering peel retention. Terminal products from this configuration are residential and commercial glass-backsheet modules in 54-cell, 60-cell, 72-cell, 120 half-cell, and 144 half-cell formats, typically using 182 mm or 210 mm wafer-based cell strings.
| Downstream configuration | Film layup | Total encapsulant mass | Lamination window | Terminal product |
|---|---|---|---|---|
| Glass-backsheet c-Si modules | 0.45 mm front / 0.45 mm rear | 850–900 g/m² | 145–150 °C, 8–10 min, 0.06–0.08 MPa | Residential and utility glass-backsheet modules |
| Bifacial glass–glass TOPCon/HJT | 0.50 mm front / 0.50 mm rear | 950–980 g/m² | 150 °C, 10–12 min, 0.05–0.07 MPa | Utility bifacial modules, carports |
| Thin-film CdTe/CIGS | 0.45 mm front / 0.45 mm rear | 850–900 g/m² | 140–150 °C, 8–12 min, 0.04–0.06 MPa | Utility and facade thin-film modules |
| BIPV laminated safety glass | 0.45 mm × 2–3 plies per interlayer | 900–1350 g/m² | 135–140 °C, 20–30 min, 0.08–0.10 MPa | Spandrels, skylights, canopies |
| Agrivoltaic glass–glass panels | 0.45 mm front / 0.45 mm rear | 850–900 g/m² | 145–150 °C, 10–12 min, 0.05–0.07 MPa | Greenhouse and open-field agrivoltaics |
| Lightweight dual-glass roofs | 0.45 mm front / 0.45 mm rear | 850–900 g/m² | 135–140 °C, 8–10 min, 0.03–0.05 MPa | Vehicle-integrated PV roofs |
Glass–glass bifacial encapsulation differs from glass-backsheet processing because the rear Su406 ply must provide adhesion to an alkali-free textured glass rather than to a polymer backsheet, and the absence of a breathable backsheet traps volatiles at the module edge. When a 2.0 mm front glass and a 2.0 mm rear glass are used, the formulation addition ratio is 0.50 mm Su406 on both sides of the cell string, giving a total encapsulant mass of 950–980 g/m² and a laminate thickness of approximately 5.0 mm after edge trim. Compliance for this configuration is verified under IEC 61215-1:2021, IEC 61215-2:2021, IEC 61730-1:2016, and IEC 61730-2:2016; bifacial performance is additionally checked under IEC TS 60904-1-2:2019 for current-voltage measurement, while optical transmittance through the laminated stack is measured by IEC 62788-1-4:2020 and ASTM E903-20. Because the rear glass transmits environmental UV-A, the UV transmittance of the rear Su406 ply is tracked after lamination to separate acceptable transmission losses from early yellowing during UV preconditioning. The downstream process uses a dual-chamber glass-glass laminator with edge pin locators and a silicone diaphragm, not a roll laminator, because edge creep is the dominant failure mode when the melt viscosity of Su406 drops during the initial ramp above 80 °C. A two-stage vacuum profile with a first-stage hold at -0.095 MPa for 3–4 min is required to evacuate air from the glass–glass cavity before full mechanical pressure at 0.05–0.07 MPa is applied. Cure at 150 °C for 10–12 min is common when the laminator has sufficient platen temperature uniformity; however, process engineers must verify that the glass temperature at the module centre reaches the peroxide decomposition threshold rather than relying on chamber air temperature alone. Amine-based glass-cleaning residues should be avoided because they can neutralize acidic migration species at the glass/EVA interface and reduce gel content below 75%. On dual-chamber lines with shared vacuum pumps, throughput bottlenecks occur when the first-stage vacuum is moved to the second chamber before the module centre reaches 80 °C; this produces visible edge bubbles at the ribbon exits. Batch-to-batch gel content for Su406 should be tracked by ASTM D2765-16 before lamination starts, because a batch at the low end of the 75% window may require an additional 2 min of cure when platen temperature drops below 149 °C. The terminal product class covers bifacial TOPCon and HJT glass–glass utility modules, carport arrays, and sound barriers where rear-side irradiance collection is economically measurable.
CdTe and CIGS module lines place Su406 in the front ply because the transparent conductive oxide and buffer layers already constrain optical throughput in the blue and UV bands, and an additional encapsulant absorption loss in the 320–400 nm region directly reduces short-circuit current. The addition ratio for thin-film front-contacted glass is 0.45 mm front and 0.45 mm rear Su406 over the monolithic cell aperture, corresponding to 850–900 g/m² and a coverage ratio of 1.05:1 relative to the TCO-coated area to allow edge trim without pulling film from the active cell. Compliance for thin-film configurations is reviewed against the IEC 61215-1:2021 and IEC 61215-2:2021 design qualification and test procedure framework, IEC 61730-1:2016 and IEC 61730-2:2016 for safety, and IEC 62788-1-4:2020 for optical transmittance of the encapsulant in the laminated state. The downstream production process is either a roll laminator with a 2.4 m working width or a diaphragm vacuum-bag laminator, depending on substrate size; the substrate preheat is kept below 90 °C for no more than 2 h before lamination because Su406 contains a peroxide initiator that can begin premature decomposition under prolonged preheating. Lamination is executed at 140–150 °C for 8–12 min with mechanical pressure of 0.04–0.06 MPa, and gel content is checked against the 75–85% xylene-extraction window. Roll-laminate CdTe lines that use Su406 must set the roll gap to the film thickness plus 0.1 mm compression, because high shear in the melt can displace cell interconnect ribbons and create edge bleed. The UV transmittance of the front Su406 ply after lamination is measured at 380 nm on a bare glass edge coupon to confirm that the film did not undergo oxidative yellowing during the preheat step. Terminal products are CdTe and CIGS utility modules, building facade modules, and custom architectural thin-film laminates where the front encapsulant must not behave as an optical filter.
A BIPV spandrel line producing laminated safety glass units typically interposes Su406 film between a 5.0 mm heat-strengthened outer glass and a 5.0 mm tempered inner glass containing embedded solar cells. The interlayer addition ratio is two to three plies of 0.45 mm Su406 per laminated unit, creating a 0.90–1.35 mm interlayer and contributing 900–1350 g/m² of encapsulant mass before edge trimming. Regulatory compliance in this downstream segment is governed by ISO 12543-2:2021 for laminated safety glass construction and durability, EN 12600:2002 for pendulum impact classification, and the IEC 61215-1:2021 and IEC 61730-1:2016 photovoltaic qualification requirements when the laminate is electrically active. The downstream process uses a vacuum-bag laminator rather than an autoclave; the stack is heated at 135–140 °C for 20–30 min under a pressure of 0.08–0.10 MPa, with optical inspection after lamination for edge voids and interlayer thickness deviation. The line must hold the laminate above the peroxide half-life threshold long enough to obtain sufficient crosslink density without residual bubble nucleation. Neutral-cure silicone structural sealant compatibility must be tested on the cut edge because published data for this exact Su406 grade in contact with neutral-cure silicone is limited. Terminal product types include BIPV spandrel panels, skylights, canopies, balustrades, and acoustic barriers where a safety-glass interlayer and photovoltaic function are specified in the same unit.
Agrivoltaic glass–glass panels using Su406 specify a formulation addition ratio of 0.45 mm front and 0.45 mm rear film, producing a total encapsulant mass of 850–900 g/m² and maintaining a continuous optical path from the low-iron anti-reflective glass through the encapsulant to the cell surface. The compliance framework includes IEC 61215-1:2021 and IEC 61730-1:2016 for module qualification and safety, ISO 9050:2003 for light transmittance through the laminated glazing, and ASTM E903-20 or IEC 62788-1-4:2020 for spectral transmittance verification. The downstream process is a glass-glass lamination cycle at 145–150 °C for 10–12 min with mechanical pressure not exceeding 0.07 MPa, because excessive pressure in the melt phase can cause edge extrusion into the glass rebate and create a cosmetic defect at the mounting clamp. UV-A transmittance in the 315–400 nm range is a primary optical parameter, but published data for this specific Su406 configuration in agrivoltaic crop systems is limited; therefore the panel manufacturer should conduct a design-of-experiment against crop-specific action spectra rather than relying on nominal UV transmittance alone. The terminal product class is greenhouse-mounted and open-field agrivoltaic arrays where the transmitted UV-A component may influence pollinator behaviour, secondary metabolite accumulation, or disease pressure depending on the crop and glass specification.
Vehicle-integrated photovoltaic roofs and lightweight building roof modules use two plies of 0.45 mm Su406 as the interlayer between 1.6 mm chemically strengthened glass sheets; the formulation addition ratio is 1:1 front-to-rear coverage, contributing 850–900 g/m² of encapsulant mass. Compliance for this segment is evaluated under IEC 61215-1:2021 and IEC 61730-1:2016 for photovoltaic safety, with additional mechanical verification under EN 12600:2002 for impact classification and ISO 12543-2:2021 for laminated safety glass durability. The downstream process uses a low-pressure laminator with a maximum diaphragm pressure of 0.03–0.05 MPa and a cure temperature of 135–140 °C for 8–10 min, because 1.6 mm chemically strengthened glass is intolerant of high clamping force and rapid thermal gradients. The 3.2 mm edge seal interface must be inspected after lamination for butyl displacement and EVA bleed; if the edge seal shows more than 0.5 mm movement, the lamination pressure or glass preheat must be reduced. Published data for long-term UV transmittance retention of Su406 in curved vehicle roof laminates is limited, so UV-A transmittance after 1000 h of ISO 4892-2:2013 weathering should be benchmarked before series production. Terminal product types are vehicle-integrated photovoltaic roofs, solar roof tiles, and lightweight portable PV panels where mass per watt and impact resistance are specified together.
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FIRST Super Fast-Cure EVA Film Su406 (UV transmittance) is an ethylene-vinyl acetate copolymer encapsulant formulated for photovoltaic module lamination in which ultraviolet radiation in the 300–380 nm band is intentionally transmitted to the cell plane or interfacial layers. The Su406 designation is a fast-cure film supplied as roll stock in nominal thicknesses of 0.45 mm and 0.50 mm with a standard roll width of 1,000 mm. The cure system uses a modified peroxide package and a silane coupling agent system to reduce vacuum-lamination dwell time relative to standard-cure EVA. The term “UV transmittance” differentiates the grade from conventional UV-blocking EVA films that use high loadings of benzotriazole or benzophenone absorbers to cut off wavelengths below 360–380 nm.
Primary usage is front-side encapsulation in glass-glass, bifacial, and building-integrated photovoltaic modules. The film is also evaluated in research-scale tandem and wide-bandgap cell platforms where ultraviolet photons contribute to the top cell current. It is not recommended for modules with UV-sensitive backsheets unless a separate UV-screening layer is present. Table 1 summarizes representative property data drawn from supplier technical literature for fast-cure UV-transmitting EVA films; the batch-specific certificate of analysis governs final lamination acceptance.
| Property | Test method | Representative value / range |
|---|---|---|
| Nominal thickness | Supplier roll tolerance | 0.45 mm ± 0.05 mm; 0.50 mm ± 0.05 mm |
| Roll width | Supplier slit tolerance | 1,000 mm +2 mm/−0 mm |
| Density | ASTM D1505-18 | 0.95–0.97 g/cm³ |
| Melt mass-flow rate, 190 °C / 2.16 kg | ISO 1133-1:2022 | 20–35 g/10 min |
| Total luminous transmittance | ASTM D1003-21 | ≥ 91% after lamination |
| UV transmittance at 350 nm | ASTM E903-20, integrating sphere | 60–80% after lamination |
| Gel fraction after cure at 145 °C / 10 min | ASTM D2765-16 | ≥ 75% |
| Tensile strength, machine direction | ISO 527-3:2018 | 8–12 MPa |
| Elongation at break, machine direction | ISO 527-3:2018 | ≥ 400% |
| Peel adhesion to glass, 180° | ASTM D6862-11 | ≥ 40 N/cm |
Film production is performed by cast-film extrusion from a twin-screw compounding line with gravimetric feeding of the peroxide masterbatch. An online beta-gauge scanner records total thickness variation across the web and controls the die bolt actuators. The supplier accepts a total thickness variation of ±5% of nominal. Thickness variation greater than ±5% can produce non-uniform cure because thicker regions retain exothermic heat while thinner regions lose heat to the platen. The film is wound on 150 m rolls for 0.45 mm stock and 130 m for 0.50 mm stock.
The melt mass-flow rate of 20–35 g/10 min is selected to ensure that the film can displace air from the cell surface and glass micro-texture before the gel fraction exceeds 30%. Once the gel fraction exceeds 30%, the storage modulus increases and flow is effectively arrested. At a platen temperature of 145 °C, the film transitions from melt to gel within 4–6 min. Differential scanning calorimetry according to ASTM D3418-21 exhibits a cure exotherm peak between 95 °C and 105 °C at 10 °C/min under nitrogen, which is 5–10 °C lower than standard-cure EVA. This lower onset supports shorter dwell but reduces the maximum safe platen temperature because premature crosslinking can occur during hot-roll feed if the film exceeds 110 °C before full air evacuation.
Regulatory compliance is limited to RoHS Directive 2011/65/EU and REACH Regulation (EU) No 1907/2006. No FDA 21 CFR clearance is claimed for this photovoltaic encapsulant.
Fast-cure formulations reduce total lamination cycle time, but they also narrow the processing window. On oil-heated single-chamber vacuum laminators with effective platen dimensions of 2,200 mm × 3,600 mm, platen edge-to-center temperature differences of 2–5 °C are common. If the edge temperature falls below 135 °C, gel fraction at the module perimeter can remain below 65%, producing adhesion loss after thermal cycling. If the center temperature exceeds 155 °C, volatile decomposition by-products from the peroxide package can form bubbles before the membrane pressure stage consolidates the stack. Multi-tier laminators often require tier-specific offset temperatures because radiant heating from adjacent tiers can raise the uppermost platen temperature above the setpoint.
The vacuum profile should be set so that the film reaches 80–100 °C under vacuum before the crosslinking exotherm accelerates. A two-stage profile is used: evacuation to 0.5–1.0 mbar for 4–6 min, then membrane pressurization to 0.08–0.12 MPa during the cure plateau. Vacuum pumps should be sized to reach 1 mbar in the chamber within 3–5 min after closing. Residual oxygen at the film/backsheet interface inhibits peroxide-initiated crosslinking; vacuum below 10 mbar is necessary to avoid surface tack loss and interfacial delamination. In production trials, the fast-cure grade has reduced cycle time from 18–22 min to 11–14 min for a stack consisting of 3.2 mm low-iron glass, EVA, cell string, EVA, and polyolefin backsheet. Thin glass of 2.0 mm or less requires a platen setpoint reduction of 3–5 °C to prevent overcure at the center.
Textured glass imposes an additional constraint. The EVA melt must penetrate the texture features before the gel fraction exceeds 20–30%, after which flow is effectively arrested by the increasing storage modulus. The fast-cure package leaves a flow window of 2–4 min after melting at 145 °C. If the vacuum stage is too short or the film temperature rises too quickly, air pockets remain at the glass interface. Process engineers should complete the evacuation phase before the film reaches 110 °C. In-line optical inspection after lamination should monitor for edge bubbles and delamination at the busbar edges. When these defects appear, the first corrective action is platen temperature mapping and vacuum verification; increasing dwell time alone may overcure the center and increase yellowing without restoring edge adhesion.
Under this service condition, the stabilizer package is reformulated to reduce UV absorber concentration without eliminating radical-scavenging capacity. In conventional UV-blocking EVA, the 10% cut-off wavelength is typically 360–380 nm. In Su406, the cut-off is shifted to approximately 320 nm. Transmittance at 350 nm after lamination is 60–80% when measured according to ASTM E903-20 with an integrating sphere. The measurement uses a glass/EVA/glass coupon to suppress rear-surface reflectance artifacts and is reported after lamination and cure.
The shift is achieved by reducing the concentration of UV-absorbing benzotriazole or benzophenone stabilizers and increasing the hindered amine light stabilizer fraction. The hindered amine system traps free radicals formed by UV-induced chain scission, but it does not absorb UV radiation to the same extent as a benzotriazole or benzophenone package. The grade is therefore best described as a short-wavelength-shifted encapsulant rather than a true UV-transparent encapsulant. Total UV transmittance below 300 nm remains low because the EVA matrix absorbs strongly in the UV-B and UV-C ranges.
Applications for this spectral response include building-integrated photovoltaic modules with photocatalytically active glass interlayers, modules with UV-curable edge sealants, and research-scale tandem devices where a wide-bandgap subcell absorbs below 400 nm. The film is not interchangeable with UV-blocking grades on the front side of a standard opaque module because the increased transmitted UV can cause backsheet yellowing and loss of mechanical integrity in the absence of a UV barrier. Conversely, standard UV-blocking EVA should not be substituted in applications that depend on UV photon flux at the cell plane.
| Parameter | Su406 UV-transmittance | Standard UV-blocking fast-cure EVA |
|---|---|---|
| Spectral cut-off, 10% transmittance | ≈ 320 nm | 360–380 nm |
| Transmittance at 350 nm | 60–80% | < 5% |
| UV absorber package | Reduced triazine/benzotriazole loading; hindered amine stabilizer dominant | High-efficiency UV absorber loading |
| Typical lamination dwell at 145 °C | 8–12 min | 12–18 min |
| Initial yellowness index | ≤ 2.0 (ASTM E313-20) | ≤ 2.0 (ASTM E313-20) |
| Damp-heat adhesion retention, 85 °C/85% RH, 1,000 h | ≥ 60% of initial | ≥ 70% of initial |
For Su406 specifically, independent multi-laboratory round-robin data are limited; the film should be qualified on the intended module stack under IEC 61215-1:2021 MQT 12 damp-heat and MQT 10 UV preconditioning. Accelerated weathering of laminated specimens is also performed according to ISO 4892-3 Method A with a 340 nm UVA lamp at 0.76 W/m²/nm and a black-standard temperature of 60 °C. After 1,000 h exposure, the yellowness index change is generally less than 2.0 units when the film is cured to a gel fraction above 75%. Damp-heat adhesion retention is evaluated at 85 °C and 85% relative humidity for 1,000 h. A retention criterion of ≥ 60% of initial 180° peel strength is typical for UV-transmitting fast-cure EVA. The lower retention relative to UV-blocking grades is not a product defect but a design trade-off arising from reduced UV absorber loading.
Moisture control is more important in the UV-transmittance grade than in UV-blocking EVA because a portion of the stabilizer system that would otherwise buffer radical reactions at the glass surface is not present. The silane coupling agent reacts with glass silanol groups during lamination. If moisture is present, the silane can form siloxane oligomers before contacting the glass surface, reducing the density of covalent bonds and lowering damp-heat adhesion retention. This failure mode is observed as adhesion loss at the glass/EVA interface without a corresponding loss in gel fraction.
Roll stock should be stored in the original sealed packaging at 20–30 °C and below 60% RH. If the film has been exposed to RH above 60% for more than 48 h, a drying step at 40 °C for 4–6 h in a dehumidified oven is required before lamination. Moisture uptake above 0.1% can hydrolyze the silane coupling agent during lamination and reduce glass adhesion. Cold rolls should be acclimated for at least 12 h at the lamination site to prevent condensation on the unwind station.
The film is incompatible with amine-based edge sealants and certain silicone room-temperature vulcanizing compounds that release acetic acid during cure. These substances can quench peroxide radicals at the module edge and produce localized undercure. Glass cleaning residues containing citric acid, hydrofluoric acid, or fluorosilicic acid should be removed with deionized water before film placement. Sulfur-containing edge tapes are also not recommended because sulfur can poison the peroxide curing system and reduce gel fraction at the perimeter.
Post-lamination cure uniformity is assessed by sampling gel fraction from the center and four corners of a sacrificial module. A center-to-edge difference greater than 10 percentage points indicates insufficient platen temperature uniformity or premature crosslinking before vacuum completion. On well-mapped single-chamber laminators, a difference below 5 percentage points is achievable. For glass-glass laminates, a post-cure oven at 130–140 °C for 20–30 min is used to complete interfacial silane condensation, not to increase gel fraction. Edge bubbles cannot be removed by post-cure; additional thermal exposure may expand the gas volume and worsen the defect.
Electrical insulation is not the primary selection factor for most crystalline-silicon module designs, but the cured film typically meets volume resistivity ≥ 1.0 × 1014 Ω·cm when measured according to ASTM D257-19 at 500 V and 25 °C. This value supports leakage-current control in thin-film and glass-glass packages, although the encapsulant is not certified as a primary electrical insulator.
In glass-glass bifacial modules with a reflective rear surface, the front-side use of Su406 is appropriate only when the rear-side encapsulant remains UV-blocking or the rear glass carries a UV-screening layer. If both sides transmit UV, the rear-side UV dose can exceed the design limit of organic backsheet components, junction box adhesives, and structural edge tapes. The resulting photolytic degradation typically appears first at the junction box bond line and module corners, where reflected radiation is not shaded by the cell.
