| HS Code | 234450 |
| Product Name | Betterial Anti-acidic, high-transparency EVA Solar Film B601S |
| Brand | Betterial |
| Model | B601S |
| Type | EVA solar encapsulant film |
| Anti Acidic | Yes |
| High Transparency | Yes |
| Thickness | 0.45 mm / 0.50 mm |
| Width | 1000-2200 mm |
| Light Transmittance | ≥91% |
| Density | 0.94 g/cm³ |
| Melting Point | 65-75 °C |
| Melt Flow Rate | 20-30 g/10 min |
| Volume Resistivity | ≥1×10^15 Ω·cm |
| Adhesion To Glass | ≥60 N/cm |
| Adhesion To Backsheet | ≥40 N/cm |
| Shrinkage | ≤3% |
| Uv Cut Off Wavelength | ≤360 nm |
| Tensile Strength | ≥18 MPa |
| Elongation At Break | ≥500% |
| Haze | ≤2% |
| Refractive Index | 1.48 |
| Thermal Conductivity | 0.23 W/m·K |
| Dielectric Constant | 2.5-3.0 |
| Water Vapor Transmission Rate | ≤10 g/m²·day |
| Shelf Life | 12 months |
As an accredited Betterial Anti-acidic, high-transparency EVA Solar Film B601S factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
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Lamination of monofacial passivated-contact cell strings into 3.2 mm low-iron rolled glass / encapsulant / cell / encapsulant / weathering-grade backsheet stacks is the highest-volume downstream route for high-transmittance EVA film in utility and rooftop modules. In this configuration, the anti-acidic EVA film is positioned as both the front-side cell embed and the rear-side protective film at a nominal area weight of 430 g/m² per side, producing a post-lamination encapsulant thickness of 380–420 µm and an EVA mass fraction of 8–11 wt% of the total laminate weight. The layup ratio is commonly expressed by glass-to-EVA-to-backsheet thickness as 3.2 mm / 0.40 mm / 0.30 mm, though front-side film can be raised to 450 g/m² when cell interconnect wire relief exceeds 0.15 mm. Flatbed diaphragm laminators with platen dimensions of 2.2 m × 3.2 m and oil-heated platens controlled to ±2°C are used; the vacuum chamber is evacuated to <1 mbar before the silicone membrane exerts 0.9–1.0 bar gauge pressure. The cure plateau is held at 145–155°C for 12–18 min, with platen temperature set 5–8°C above the crosslinking onset of the peroxide package. Experience on multi-opening laminators indicates that excessive vacuum before membrane contact produces edge bleed when melt viscosity drops below 2,000 Pa·s; conversely, early membrane pressure traps air at cell ribbon edges and generates bubble defects after damp heat exposure. A gel content of 75–85 wt%, determined by extraction in boiling xylene per ASTM D2765-16, is the typical acceptance window; gel fractions below 70 wt% correlate with creep-induced cell displacement in thermal cycling, while gel fractions above 90 wt% decrease interfacial adhesion to tin-coated copper ribbons. Storage and preconditioning boundary: unopened films are held at 20–25°C and 40–60% RH; if ambient RH exceeds 60%, pre-drying at 40°C for 24 h is required to prevent moisture-derived bubble formation. The anti-acidic system limits free acetic acid evolution after 1,000 h of damp heat at 85°C/85% RH when tested according to IEC 61215-1:2021 MQT 13; modules are qualified under IEC 61215-1:2021 and IEC 61730-1:2016 for safety construction. The terminal products are utility-scale and commercial roof modules with front-side weighted hemispherical transmittance above 91% at 550 nm when measured on glass/EVA/glass laminates per ASTM E903-20. Finished modules are framed with anodised aluminium and fitted with junction boxes, with encapsulant edge pull-through kept at 0.3–0.8 mm from the glass edge.
Glass-glass bifacial heterojunction or TOPCon modules replace the polymeric backsheet with 2.0 mm heat-strengthened glass, so the thermal mass of the stack rises by approximately 35–45% relative to single-glass layups. The layup becomes front glass / B601S film / string matrix / B601S film / rear glass with edge tape; the rear EVA film is typically upgraded to 450–500 g/m² because the rear transparent surface must fill both cell-to-glass gaps and the smaller curvature of thin glass without excessive squeeze-out. On a 2.2 m × 2.6 m double-glass module, the EVA layer mass ratio is roughly 0.9–1.1 kg/m² of module area, but cured thickness is less uniform than in backsheet laminates, with mid-panel thickness 350–380 µm and edge-ribbon zones 300–330 µm when membrane pressure exceeds 0.95 bar. The vacuum profile is rebalanced: a 4–6 min tacking phase at 80–100°C under 0.4–0.6 bar locates the strings and removes air, followed by a 3–5 min ramp to 148–152°C under 0.85–0.95 bar. Production-scale laminators with central or split silicone membranes show that raising nip pressure too early increases glass edge squeeze-out and reduces edge seal width to below 2 mm, which later admits moisture ingress under IEC 61215-1:2021 MQT 13. The anti-acidic EVA must meet a post-lamination gel content of 78–88 wt% per ASTM D2765-16 and maintain optical coupling to both front and rear glass; laminates are inspected by visual transmission per IEC 61215-1:2021 MQT 01 and by front-side hemispherical transmittance per ASTM E903-20. Terminal products are bifacial rooftop and ground-mount modules with rear-side irradiance gain measured according to IEC 60904-1-2:2019; the finished package is framed or clamp-mounted without a backsheet, making the encapsulant the principal barrier against acid and moisture at the rear glass-cell interface.
| Parameter | Single-glass backsheet stack | Glass-glass bifacial stack |
|---|---|---|
| Front EVA area weight | 430–450 g/m² | 450–500 g/m² |
| Rear EVA area weight | 430 g/m² | 450–500 g/m² |
| Lamination cure plateau | 145–155°C, 12–18 min | 148–152°C, 15–22 min |
| Membrane pressure | 0.9–1.0 bar | 0.85–0.95 bar |
| Post-cure gel content | 75–85 wt% | 78–88 wt% |
| Primary process failure | Ribbon edge bubbles | Edge squeeze-out and seal loss |
On flexible thin-film CIGS or amorphous silicon cell circuits sputtered onto 25–50 µm stainless steel foil or 50–125 µm polyimide, roll-to-roll vacuum laminators operating at 0.2–0.5 m/min apply the B601S film at 200–350 g/m² as a front transparent dielectric and back encapsulant. The layup ratio of film to substrate is selected to keep total laminate thickness below 0.8 mm so that the module can be rolled for transport; because thermal exposure of the semiconductor junction is limited, the lamination belt is set to 120–135°C for 8–12 min, yielding a gel content of 65–75 wt% per ASTM D2765-16. Compliance for flexible thin-film modules is assessed under IEC 61215-2:2021 hot-spot, flex, and damp heat sequences; optical gain is quantified by ASTM E903-20 direct transmittance. The finished products are portable off-grid chargers, solar awnings, and adhered roof membranes where the anti-acidic film reduces acetic acid migration into the transparent conductive oxide layer. Published data for this specific flexible configuration is limited, so the 65–75 wt% gel content range should be verified on the actual roll-to-roll line before setting release specifications.
Building-integrated photovoltaic modules for façades, spandrels, skylights, and canopies frequently use asymmetric layups: a 6–10 mm tempered or heat-strengthened outer glass, a 0.38–0.76 mm PVB or EVA interlayer, a 0.4–0.5 mm B601S encapsulant around the cell string, and a lightweight polymer backsheet or a second thin glass. The stack ratio is driven by wind-load deflection limits rather than optical mass; for a 1.5 m × 2.0 m façade module, the front glass may be 8 mm, the rear encapsulant 450 g/m², and the edge sealant polyisobutylene at a 12–15 mm width. Lamination on an autoclave or flatbed laminator requires a two-step pressure sequence: 5 min at 110–125°C and 0.4–0.6 bar to remove air, then 20–30 min at 135–145°C and 0.95–1.05 bar to cure the EVA and bond to the as-cast glass surface. Process conflict arises from asymmetric thermal expansion: 8 mm glass acts as a heat sink and slows front-side crosslinking rate, while the backsheet side heats faster, leading to non-uniform gel content if platen toplates are not independently zoned. Qualification under IEC 61215-1:2021 and IEC 61730-1:2016 is supplemented by EN 12600:2002 pendulum impact for overhead glazing and by the building code reaction-to-fire requirement; high-transparency EVA must retain luminous transmittance above 90% according to ASTM D1003-13 when laminated with low-iron glass. The terminal products are BIPV curtain wall units, skylight laminates, and canopy panels that serve as both envelope and power generator, with the anti-acidic formulation reducing delamination risk in humidity-condensing cavities.
Floating photovoltaic arrays on reservoirs, tidal flats, and industrial water bodies place the encapsulant under sustained humidity, temperature cycling, and dilute acidic or saline aerosols, so the module is normally a double-glass construction without a backsheet. In this configuration, 2.0 mm or 2.5 mm heat-strengthened glass sheets are coupled with two B601S films at 450–500 g/m² each; the finished laminate thickness is 6.8–7.8 mm and the EVA constitutes roughly 10–14 wt% of the total mass. Process control is tighter than in terrestrial single-glass production: the laminator vacuum is held below 0.5 mbar for 5–7 min, membrane pressure is ramped to 0.85–0.90 bar only after melt wet-out is visually complete, and the curing plateau is maintained at 145–150°C for 18–22 min to compensate for the heat-absorbing water-facing glass. Experience on multi-chamber laminators demonstrates that float-glass stacks retain heat during exit cooling; if modules are unloaded above 50°C, the EVA at the centre remains above the softening point and can creep under framing pressure, causing thickness gradients of ±40 µm. Salt mist resistance is evaluated under IEC 61701:2020, ammonia resistance under IEC 62716:2013, and damp heat under IEC 61215-1:2021 MQT 13; the anti-acidic EVA is specified because acetic acid generated by conventional EVA under high humidity can corrode cell fingers and interconnect metals. The terminal products are floating water surface modules with sealed junction boxes and foam floats, where the encapsulant must maintain adhesion to glass after 15,000 h of wet exposure in accelerated sequential testing. Published data on the 15,000 h sequential test for B601S is limited; validation on the specific glass type and edge seal is required.
| Application route | Standard or method | Monitored parameter |
|---|---|---|
| Single-glass monofacial module | IEC 61215-1:2021 MQT 13 | 1,000 h damp heat resistance |
| Glass-glass bifacial module | IEC 60904-1-2:2019 | Bifacial rear-side irradiance response |
| Flexible thin-film module | IEC 61215-2:2021 | Hot-spot, flex, damp heat sequences |
| BIPV façade and skylight | EN 12600:2002 | Pendulum impact resistance |
| Floating double-glass module | IEC 61701:2020; IEC 62716:2013 | Salt mist and ammonia corrosion resistance |
| Vehicle-integrated PV | ASTM E903-20; ASTM D1003-13 | Solar transmittance and haze |
For vehicle-integrated photovoltaic modules laminated into glass roofs, bus roof caps, or rail carriage glazing, the EVA film must follow double-curvature surfaces while retaining a cell-to-ribbon bond that withstands mechanical vibration and thermal shock. The stack uses a 2.1–3.2 mm chemically or thermally tempered outer glass, a 0.4–0.5 mm B601S film, a shingled or standard cell string, a second 0.4 mm film, and a thin 0.7–1.1 mm glass or polymer inner skin; the total build ratio is selected so that the final laminate passes ECE R43 impact requirements for roof glazing where applicable in the target region. Lamination is performed in a curved-glass vacuum press at 125–140°C for 25–35 min, with the EVA melt phase kept below 1,500 Pa·s through the initial forming stage; additional cure time at 145°C may be required for the central region of highly curved panels because the glass radiative heat loss creates a temperature difference of 8–12°C between edge and centre. The anti-acidic film is preferred for VIPV applications subject to repeated solar soak at 105°C black panel temperatures, because conventional EVA can release acetic acid that attacks the conductive ribbon within the cell string; optical performance is verified by ASTM D1003-13 haze below 2% on glass/EVA/glass laminates and by ASTM E903-20 solar transmittance. The terminal products are factory-installed solar roofs, charging canopies for electric vehicles, and semi-transparent rail-mounted PV panels. A limitation is the incompatibility with amine-based edge sealants, which are avoided because they can prematurely consume the peroxide cure package and lower the final gel content below the 70 wt% acceptance floor.
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The product identified as Betterial Anti-acidic, high-transparency EVA Solar Film B601S is a fast-cure ethylene-vinyl acetate encapsulant film designed for vacuum lamination of crystalline silicon photovoltaic modules. Manufacturer-documented specifications place the film thickness at 0.45 mm and 0.60 mm roll formats, with a solar transmittance over the 400–1100 nm range of ≥91.5% when measured according to ASTM D1003-21. The formulation incorporates an acid-scavenging package intended to limit acetic acid accumulation during damp-heat aging, while retaining the cure and adhesion profile of conventional EVA on standard lamination lines. The film is supplied in roll widths from 670 mm to 2200 mm depending on module string layout, and is intended for both single-glass and double-glass module constructions.
B601S is based on a poly(ethylene-co-vinyl acetate) matrix with a vinyl acetate content in the 28–33 wt% range, as is typical for photovoltaic encapsulation grades. The crosslinking system uses an organic peroxide initiator with a one-hour half-life temperature appropriate for 135–150°C lamination cycles, and the silane adhesion promoter enables bonding to glass and polyester backsheet surfaces. The anti-acidic function is obtained by incorporating a dispersed metal-oxide acid acceptor within the polymer matrix; the acid acceptor reacts with acetic acid released by vinyl acetate hydrolysis under 85°C/85% RH aging. This mechanism differs from simple pH-neutralizing additives because the reaction products remain immobilised in the cured network rather than migrating to cell surfaces. Melt flow rate at 190°C/2.16 kg is documented as 25–35 g/10 min per ISO 1133-1:2022, which maintains flow into inter-cell gaps without excessive squeeze-out at module edges.
Production-scale cast-film extrusion on a slot-die line with a die width of 2200 mm is used to control thickness variation within ±0.03 mm. Inline corona treatment raises surface energy on the embossed film side to ≥52 mN/m to reduce air entrapment during glass layup. Because the acid acceptor is incorporated during melt compounding, batch-to-batch variation in acetic acid uptake is mitigated by controlling moisture below 0.10 wt% before extrusion and by monitoring gel content after cure at 145°C for 18 min according to ASTM D2765-16.
Optical and electrical verification data supplied with B601S are summarised in Table 1. Total luminous transmittance and haze are determined on laminated glass/EVA/glass coupons, not on free film, because the encapsulant optical path differs after lamination.
| Property | Test method | Documented value or range | Unit |
|---|---|---|---|
| Thickness, standard sheet | ASTM D374-16 | 0.45 ± 0.03 | mm |
| Thickness, double-glass grade | ASTM D374-16 | 0.60 ± 0.04 | mm |
| Solar transmittance, 400–1100 nm | ASTM D1003-21 | ≥91.5 | % |
| Haze | ASTM D1003-21 | ≤3.0 | % |
| Melt flow rate, 190°C/2.16 kg | ISO 1133-1:2022 | 25–35 | g/10 min |
| Gel content after 145°C/18 min cure | ASTM D2765-16 | 70–90 | % |
| Peel strength to glass | ASTM D6862-11 | ≥60 | N/cm |
| Peel strength to PET backsheet | ASTM D1876-08 | ≥40 | N/cm |
| Volume resistivity, cured film | IEC 62631-3-1:2016 | ≥1.0 × 1014 | Ω·cm |
| Shrinkage after cure | ASTM D2732-14 | ≤5.0 | % |
These values are manufacturer-reported for the standard anti-acidic formulation. Published independent data for this specific film configuration is limited; therefore, module qualification should confirm the values on the actual module stack and laminator profile. The volume resistivity is measured after full peroxide cure because residual peroxide and acid acceptor distribution change the dielectric response before crosslinking is complete.
B601S is processed in a flat-bed vacuum laminator with a chamber temperature set point between 145°C and 150°C. The recommended cure plateau is 15–18 min after the module reaches temperature, which corresponds to a gel content target of 70–90%. Vacuum stage pressure is held at 30–80 kPa for 4–6 min to evacuate air from the embossed film surface before membrane pressure of 80–100 kPa is applied. For double-glass modules, the 0.60 mm grade is used with edge-trim thermal history sufficient to prevent premature crosslinking before complete wet-out of cell gaps. Laminator belt speed and pin height are adjusted so that the film reaches 110°C within 3 min; slower ramp profiles can cause the peroxide to begin decomposition before full void removal, trapping gas at the cell edges.
Because B601S contains a metal-oxide acid acceptor, dispersion quality at the extruder is critical. Poor distributive mixing in a low-L/D single-screw compounding step can produce acid-acceptor agglomerates larger than 50 μm, which reduce optical clarity and increase haze beyond 3.0%. The supplier recommends melt filtration through a 100–150 μm screen pack and monitoring of pressure rise during extrusion as an indirect indicator of agglomeration. In lamination, the film does not require a pre-tack step if the glass temperature is above 20°C and relative humidity is below 60%; above this humidity, pre-drying at 60°C for 12–24 h is required to prevent moisture-induced void formation.
Anti-acidic encapsulant films are specified for module designs in which acetic acid accumulation is a known corrosion vector for cell metallization and solder alloys. In damp-heat testing at 85°C/85% RH for 1000 h according to IEC 61215-2:2021, conventional EVA can release acetic acid at rates that depend on cure state, VA content, and lamination temperature. B601S is formulated to reduce the available acetic acid inventory by chemical scavenging rather than by reducing vinyl acetate content to the point where adhesion and processability decline. This distinction is relevant for TOPCon and heterojunction cell structures, where front-side contacts are sensitive to acid penetration and where rear-side passivation stacks may promote potential-induced degradation under negative bias. The film is also used in single-glass PERC modules with aluminium backsheets and in double-glass bifacial modules with transparent backsheets, where low haze is required to maintain rear-side irradiance gain.
Current-voltage degradation during PID testing at 85°C/85% RH with −1500 V bias for 96 h as described in IEC TS 62804-1:2015 can be influenced by encapsulant ion mobility and acid content. B601S is not a zero-acid material; it is an EVA-class film with a finite vinyl acetate monomer fraction, so the acid-scavenging capacity is a consumable resource. In module designs with excessive free acetic acid generation from adjacent edge sealants or backsheet hydrolysis, the scavenger may be depleted before the warranty period. The manufacturer-documented acetic acid uptake capacity is therefore not a substitute for proper edge sealing and low-moisture ingress backsheet selection.
The 0.45 mm grade is intended for standard single-glass modules with glass thickness 2.8–3.2 mm and PET-based backsheets. The 0.60 mm grade is specified for double-glass modules and for thin-film modules where additional mechanical cushioning is required around cell edges. Both grades use the same base formulation, but the peroxide concentration is adjusted so that after the recommended lamination cycle the volumetric crosslink density is similar despite the thickness difference. In practice, the thicker film retains more heat during cooling and can continue crosslinking for several minutes after removal from the laminator; gel content measurements on immediately cooled coupons may therefore read 3–5% lower than after 24 h of room-temperature stabilization. Slitting tolerance is held to ±1.0 mm on roll widths over 1000 mm to prevent exposed glass at module edges.
The primary difference between B601S and standard EVA encapsulants is the presence of an acid-scavenging phase that competes with acetic acid for reaction at the polymer-cell interface. Standard EVA films rely on high gel content and low residual acetate to minimize acid release; however, hydrolysis under damp heat still produces acetic acid. POE encapsulants avoid vinyl acetate hydrolysis entirely and offer lower water vapor transmission, but they typically require higher lamination temperature and slower silane adhesion development to glass. B601S is positioned between these classes: it retains the 145–150°C lamination window and adhesion performance of EVA while reducing the acid accumulation rate to a level closer to polyolefin encapsulants. Comparative data from accelerated damp-heat screening are shown in Table 2.
| Property | B601S | Conventional EVA | POE |
|---|---|---|---|
| Acetic acid generation under 85°C/85% RH | Reduced via acid acceptor | Higher, increases with VA content | Minimal, no vinyl acetate hydrolysis |
| Typical lamination plateau | 145–150°C | 145–150°C | 150–160°C |
| Water vapor transmission | EVA-class, 5–10 g/m²·day | EVA-class, 5–10 g/m²·day | Lower, typically 2–5 g/m²·day |
| Adhesion to glass | ≥60 N/cm | ≥50 N/cm | ≥40 N/cm depending on silane |
| PID resistance in damp-heat bias screening | Improved over standard EVA | Limited | High |
| Processability on standard EVA laminators | No laminator profile change required | Standard | May require profile adjustment |
The water vapor transmission values are nominal ranges for 0.45–0.60 mm cured encapsulant films and vary with temperature and backing material. Direct quantitative comparison for B601S against specific POE grades should be performed with the final module stack because weathering performance is not controlled solely by encapsulant chemistry. Independent published data for this specific film configuration is limited; therefore, the comparison in Table 2 is based on encapsulant-class behavior rather than a direct B601S dataset.
Accelerated aging of B601S laminates according to IEC 61215-2:2021 damp-heat sequence is performed on full-size modules and on one-cell coupons. After 1000 h at 85°C/85% RH, qualification requires no visual delamination, no corrosion of busbar or cell interconnect regions, and power attenuation below 5%. For anti-acidic encapsulants, additional monitoring of yellowness index and adhesion retention is applied. A cured B601S coupon laminated between 3.2 mm low-iron glass and a fluoropolymer backsheet shows a yellowness index increase of less than 2.0 after 1000 h when measured per ASTM E313-20, provided the gel content before aging is at least 75%. Incomplete cure below 70% gel leaves unreacted vinyl acetate and peroxide residues that accelerate acetic acid release during damp heat.
Electroluminescence imaging after 85°C/85% RH exposure can reveal acid-related corrosion at finger lines before it appears as power loss. The anti-acidic grade is not a replacement for moisture barrier design; edge ingression from unsealed laminate edges will still transport water vapor into the module and may exhaust the scavenger. Modules with B601S should therefore maintain the edge-to-cell distance and sealant coverage specified in the module maker’s bill of materials.
B601S rolls must be stored in their original sealed packaging at 0–30°C and relative humidity below 60%. If the packaging is opened for more than 8 h at ambient humidity above 60%, the film surface can absorb moisture and generate bubbles during lamination. Pre-drying in a forced-air oven at 60°C for 12–24 h is required after such exposure. The film should not be stored near strong oxidizers or amine-based additives, because amines can interfere with silane adhesion promoter hydrolysis and reduce glass peel strength to below 40 N/cm. Shelf life from the date of production is 12 months in unopened packaging at 20°C; after expiration, gel content and melt flow rate should be retested per ISO 1133-1:2022 and ASTM D2765-16 before release to production.
