Zhejiang Feiyu FY101 White EVA Film

In monofacial crystalline silicon module manufacturing, Zhejiang Feiyu FY101 white EVA film functions as the rear-side encapsulant in glass/backsheet assemblies. The addition ratio is 100% of the rear encapsulant plane; transparent rear EVA is removed and replaced with FY101 white EVA at a product-selected layer thickness of 0.40–0.50 mm, corresponding to an areal weight of approximately 390–480 g/m² for an EVA compound with density 0.94–0.96 g/cm³. White pigmentation is obtained by melt-compounding rutile TiO₂, typically at 4–10 wt% of the film compound, into an ethylene-vinyl acetate matrix with vinyl acetate content of 28–33 wt%, together with a peroxide curing agent, a silane coupling agent, hindered-amine light stabilizers, and an antioxidant package. Before lamination, melt flow behavior is screened per ISO 1133-1:2022 at 190 °C / 2.16 kg; typical EVA encapsulant resins of this class exhibit melt volume-flow rates of 25–40 cm³/10 min, while exact FY101 values remain datasheet-controlled. The downstream lamination process uses a multi-chamber oil-heated diaphragm laminator with vacuum below 30 mbar and platen setpoints of 145–155 °C. A standard cycle of 13–17 min includes a preliminary vacuum hold at 110–120 °C to remove air from the interface before diaphragm pressure initiates peroxide crosslinking. After cure, gel content measured by solvent extraction is normally 75–92%; lower gel content is associated with creep displacement and delamination risk during IEC 61215-2:2021 MQT 11 thermal cycling. Adhesion to glass is confirmed after 85 °C/85% RH damp heat, and the module qualification path is governed by IEC 61215-1:2021, IEC 61215-2:2021, and IEC 61730-2:2016, with North American installations requiring UL 1703 listing. Terminal product types include 54-cell, 60-cell, and 72-cell monofacial PERC and TOPCon modules for utility, commercial, and residential rooftop arrays. A critical operational boundary is moisture uptake: storage or handling at RH 60% or higher without sealed moisture-barrier packaging can raise film moisture above 0.1 wt%, and pre-drying at 40–50 °C for 12–24 h is required to avoid bubble formation and acetic acid generation during cure. Amine-containing cleaning agents on the glass surface are incompatible with the peroxide cure system and must be avoided because residual amines can shift the cure exotherm and reduce adhesion uniformity.

What Limits the Use of a White Reflective Interlayer on the Rear Side of a Bifacial Glass-Glass Module?

Rear-side photon collection, not backsheet opacity, determines whether a white EVA interlayer can be used in bifacial glass-glass modules. A full-area FY101 white film on the rear side is excluded from qualified bifacial designs because it would attenuate rear-side irradiance and reduce rear-side short-circuit current; the film is instead applied as narrow cell-gap strips or perimeter border strips that redirect light escaping through front-side cell gaps. In this configuration, the addition ratio is expressed as strip area fraction relative to aperture area, with published production data indicating a practical ceiling of 8–10%; above this range, the front-side reflectance gain is usually offset by measurable rear-side current loss. Strip widths are generally 5–15 mm, with film thickness of 0.30–0.45 mm, yielding local areal weights of 285–435 g/m². The die-cut strips are placed onto the rear transparent EVA using a vacuum pick-and-place unit with placement tolerance ±1.0 mm; misregistration that shades active cell edges by more than 0.5 mm is a known cause of cell-level current mismatch and hot-spot risk during IEC 61215-2:2021 MQT 22 hot-spot endurance testing. Lamination remains a single-step vacuum cycle at 145–155 °C, but the glass-glass stack requires a longer soak than glass/backsheet structures, typically 17–22 min, to bring the rear-side EVA to gel content above 80%. Compliance is evaluated under IEC 61215-1:2021, IEC 61215-2:2021, and IEC 61730-2:2016; the insulation resistance requirements after damp heat place strict limits on conductive edge contamination during strip application. Terminal products are glass-glass bifacial modules with rear-side irradiance gain potential, used in utility fixed-tilt and single-axis tracker installations. Published data for this specific configuration is limited, and module producers are required to validate the strip pattern through ray-tracing simulation and current-voltage scanning before qualification; direct substitution of a full transparent rear encapsulant with white EVA without cell-gap pattern engineering is not a production-validated modification.

BIPV and Opaque Spandrel Lamination—Adhesion, Moisture Uptake, and Corner Seal Kinetics

Building-integrated photovoltaic and opaque spandrel assemblies use FY101 white EVA film as both encapsulant and adhesive interlayer between front glass, active solar cells or fritted decorative glass, and a rear glass or rigid substrate. The addition ratio is a full-area interlayer with thickness of 0.38–0.76 mm, corresponding to approximately 365–730 g/m²; thicker films are required when the rear substrate is textured, when ceramic frit print height exceeds 80 µm, or when the laminate includes embedded mesh, perforated metal, or stone veneer layers. The film is laid in a dust-controlled cleanroom environment, and lamination is performed in a single-chamber vacuum diaphragm press or silicone bag oven operating at pressures below 30 mbar. Because architectural laminates commonly use annealed, heat-strengthened, or fully tempered glass in thicknesses from 4 mm to 12 mm, the thermal cycle is longer than a PV module cycle: typical setpoints are 135–145 °C with a soak period of 25–40 min. This lower maximum temperature relative to PV lamination reduces the risk of temporary thermal bow in heat-strengthened glass while still achieving gel content in the 75–90% range. Adhesion and durability requirements are specified under EN ISO 12543-4:2021 for laminated glass and EN 12600:2002 for impact classification; BIPV electrical qualification remains under IEC 61215-1:2021 and IEC 61730-2:2016, with facade fire performance governed by applicable local building codes. A recognized operational boundary is the higher moisture permeability of EVA compared with PVB or ionomer interlayers; edge fog or corner delamination may occur if moisture ingress exceeds the silane grafting capacity of the interlayer. Qualified end products include BIPV spandrel panels, facade modules, skylights, and opaque glass cladding systems that combine electrical generation with building envelope functions.

For interior partition walls, table surfaces, staircase balustrades, and cabinet doors, FY101 white EVA film is processed as a pigmented interlayer between two lites of heat-strengthened or tempered glass. The film provides a diffusing white background for screen-printed or digital-printed PET interlayers and eliminates the autoclave step required for PVB. The addition ratio is a single full-sheet interlayer with gauge selected between 0.25 mm and 0.38 mm, yielding areal weights of 240–365 g/m²; films below 0.25 mm are not recommended when glass lites exceed 1500 mm in width because edge air removal becomes uneven in flatbed laminators. The downstream process involves glass cutting, edge seaming, cleaning with deionized water and isopropanol, layering glass/FY101 white EVA film/printed PET/glass, and laminating in a silicone bag or flatbed vacuum press. A typical degassing step at 85–95 °C for 20 min under vacuum of 20–30 mbar is followed by cure at 125–135 °C for 30–50 min. After cooling, impact classification is tested according to EN 12600:2002, and durability is assessed under EN ISO 12543-4:2021. The white interlayer is evaluated for Yellowness Index and luminous reflectance using ASTM E313-20, with virgin-film Yellowness Index below 2.0 and reflectance above 88%; post-aging yellowness is monitored after 1000 h damp heat. A process limitation is that EVA interlayers can develop edge haze if stored at RH > 60% before lamination; sealed foil packaging and pre-drying at 40–50 °C for 8–12 h are therefore used. Final product categories include interior glass partitions, table tops, kitchen and bathroom cabinet doors, wardrobe doors, and illuminated decorative panels.

When Re-Lamination of Field-Aged Modules Uses White EVA as a Rear Bonding Interlayer

Re-lamination work on field-aged glass/backsheet modules uses FY101 white EVA film as a rear bonding interlayer when the original backsheet has cracked or delaminated but the cell and front encapsulant remain mechanically intact. The addition ratio is 100% of the rear bonding plane at a film thickness of 0.30–0.45 mm, giving an areal weight of 285–435 g/m²; thicker films are selected only when the rear side has residual roughness after grinding or when junction-box removal leaves surface depressions. The rework process begins with junction-box disconnection and removal, preheating the module to 60–80 °C, and peeling the failed backsheet at a controlled angle below 15° to limit cell microcrack generation. Residual degraded EVA is removed by dry-ice blasting or solvent cleaning, and the exposed rear surface is primed with a silane-based adhesion promoter before the new white EVA film is placed. Lamination is carried out in a double-platen hydraulic press at 135–145 °C for 12–18 min, with an initial vacuum below 30 mbar and a final diaphragm pressure of 0.7–1.0 bar gauge. Because the front encapsulant has already been cured, re-lamination cannot restore a uniform crosslinked network across the full thickness; gel content in the new rear film is typically 80–92%, while the bond to the pre-cured front encapsulant depends on surface roughening and adhesion promoter diffusion. Compliance for the refurbished module is evaluated under IEC 61215-1:2021, IEC 61215-2:2021, and IEC 62446-1:2016 for system-level operation and maintenance; electrical safety is re-confirmed according to IEC 61730-2:2016. Terminal product types include re-qualified modules for small off-grid systems, agricultural water pumping, and secondary market rooftop installations where full-form warranty is not required. Published data for this specific configuration is limited, and re-lamination is only appropriate for modules whose front encapsulant adhesion remains within the initial qualification range after field exposure.