TL;DR — Key Takeaways
- Industrial release film is a temporary protective film used during supply chain operations to prevent surface damage and contamination
- Wansen's release film achieves surface resistivity of 10⁶–10¹¹ Ω·cm — within the ESD-safe dissipative range
- Silicone release coating provides clean, non-reactive release from composite panels, PCB substrates, and coated metal surfaces
- ESD protection is critical in electronics supply chain operations — static discharge can destroy sensitive components before they are installed
- Film must have consistent release force (not too strong, not too weak) across the entire roll length
What Is Industrial Release Film?
Industrial release film is a temporary protective film applied to the surface of manufactured components during fabrication, storage, and transit. Unlike PPF (which is a permanent paint protection solution), release film is designed to be removed — cleanly, completely, and without residue — at a defined point in the supply chain operations or assembly process.
Primary applications include:
- PCB (Printed Circuit Board) supply chain operations: Protecting the copper trace surface from oxidation and contamination during solder paste printing and component placement. The film must not generate static charge that could damage sensitive semiconductor devices.
- Composite panel supply chain operations: Protecting carbon fibre reinforced polymer (CFRP) or fibreglass composite panels from surface scratches, dust deposition, and chemical contamination during layup, curing, and trimming operations.
- Coiled metal sheet storage: Protecting polished or coated metal coils from roll-to-roll contact damage during storage and transit between processing stages.
- Glass and display panel supply chain operations: Protecting optical surfaces from scratching and contamination during cutting, edge polishing, and assembly operations.
The ESD Protection Requirement
Electrostatic discharge (ESD) is the uncontrolled transfer of electrical charge between two objects at different potentials. In electronics supply chain operations environments, ESD is one of the leading causes of latent damage to sensitive components — damage that is not immediately detectable but causes field failures months after the product is in service.
The ESD risk arises because materials become electrostatically charged through friction (triboelectric charging) during handling, unwinding, and winding operations. A release film being unwound from a roll will generate static charge due to the friction between the film and the roll core or the preceding layer. If that charge is not controlled, it can discharge into a nearby sensitive component, destroying its gate oxide or semiconductor junction.
Material surface resistivity is the key parameter for ESD control:
| Surface Resistivity (Ω·cm) | ESD Classification | Suitable For |
|---|---|---|
| <10⁴ | Conductive | Not suitable — charge dissipates too quickly, creating high discharge current |
| 10⁴ – 10⁶ | Static dissipative (lower end) | Moderate ESD protection; charge decays in 0.01–0.1 seconds |
| 10⁶ – 10¹¹ | ESD-safe dissipative (target range) | Ideal — charge decays at controlled rate, preventing sudden discharge events |
| >10¹² | Insulative | Not ESD-safe — charge accumulates and discharges suddenly at high voltage |
Wansen's industrial release film is manufactured to a surface resistivity target of 10⁶–10¹¹ Ω·cm. This range is the internationally recognised "ESD-safe" dissipative zone — charge decays at a controlled rate (typically 0.1–10 seconds depending on the exact resistivity), preventing the sudden high-current discharge events that cause component damage.
Surface resistivity (Ω·cm, or more precisely Ω/square for a sheet material) measures the resistance to current flow along the surface of the material. Volume resistivity (Ω·cm) measures the resistance through the bulk of the material. In release film applications, surface resistivity is the critical parameter because ESD events originate at the film surface. Wansen specifies surface resistivity in the 10⁶–10¹¹ Ω·cm range per ASTM D257.
Silicone Release Coating Chemistry
The release property of Wansen's industrial release film comes from a thin silicone release coating applied to one face of the base film. This coating uses a platinum-catalysed addition-cure silicone system — specifically, a vinyl-substituted polydimethylsiloxane (PDMS) crosslinked with a methylhydrogensiloxane polymer in the presence of a Karstedt's catalyst (platinum complex).
The chemistry can be summarised as follows:
- Base polymer: Vinyl-terminated PDMS provides the flexible silicone backbone. The vinyl groups are the reaction sites for the hydrosilylation crosslinking reaction.
- Crosslinker: Methylhydrogensiloxane polymer (Si-H functional) reacts with the vinyl groups of the PDMS under platinum catalysis, forming an ethyl bridge (Si-CH2-CH2-Si) crosslink between polymer chains.
- Catalyst: Karstedt's catalyst (divinyl-tetramethyldisiloxane platinum complex) accelerates the hydrosilylation reaction at temperatures from 80°C upward, allowing controlled cure at relatively low temperatures.
- Release mechanism: The crosslinked silicone network has very low surface energy (approximately 20–24 mN/m), which prevents most adhesives and polymer matrices from wetting the surface. Instead of bonding, the adhesive contacts the release coating but does not interlock with it — clean release is possible at the designed peel force.
The release force is a critical specification — it must be consistent across the roll and reproducible from batch to batch. If the release force is too high, operators will struggle to remove the film and risk damaging the underlying component. If the release force is too low, the film may delaminate prematurely during storage or transport. Wansen's release film is manufactured to a target release force range that is validated per FINAT test method FTM 1 (or equivalent) for each production batch.
Base Film Substrate — Why TPU?
While many industrial release films use polyester (PET) or polyethylene (PE) as the base substrate, Wansen's release film uses a TPU base for specific performance advantages:
- Thermal stability during processing: Many composite panel supply chain operations processes involve elevated temperatures (vacuum bagging at 120–180°C, autoclave curing at elevated pressure and temperature). TPU maintains its mechanical integrity and dimensional stability through these thermal cycles without softening, shrinking, or deforming.
- Chemical resistance: During composite layup, the release film contacts uncured epoxy or polyester resin systems. TPU has better chemical resistance to these resin systems than standard PE, reducing the risk of the film surface being attacked or partially dissolved by uncured resin.
- Controlled elongation: TPU has sufficient elongation at break to allow the film to conform to slightly curved or irregular surfaces during application without cracking or tearing — important in composite panel applications where the film must maintain complete coverage over the panel surface.
- Clean separation from composite: The silicone release coating on the TPU base provides clean release from cured composite surfaces (CFRP, fibreglass) without adhesive residue, even after high-temperature cure cycles.
Key Technical Specifications
| Parameter | Specification | Test Method |
|---|---|---|
| Surface Resistivity | 10⁶ – 10¹¹ Ω·cm | ASTM D257 |
| Release Force | 0.05 – 0.25 N/25mm (adjustable) | FINAT FTM 1 |
| Film Thickness | 50–150μm (customisable) | ASTM D2103 |
| Silicone Coat Weight | 0.8–1.5 g/m² | Internal gravimetric |
| Maximum Service Temperature | 200°C (short-term); 150°C (continuous) | Internal thermal aging |
| Elongation at Break | ≥300% | ASTM D882 |
| Tensile Strength | ≥20 MPa | ASTM D882 |
| Transparency | Clear to slightly hazy | Visual |
| Residue After Removal | None (clean release) | Internal adhesion test |
Application Scenarios in Detail
PCB supply chain operations
In PCB supply chain operations, release film (often called " ESD film" in this context) is used to protect the copper surface of bare printed circuit boards during storage and transport between supply chain operations stages. The key requirement is that the film must not generate static charge when being applied or removed, because the discharge can destroy sensitive semiconductor components that will later be placed on the board.
The film's surface resistivity of 10⁶–10¹¹ Ω·cm ensures that any static charge generated during unrolling or application dissipates safely to ground within a controlled timeframe rather than accumulating to high voltage levels. This protects both the board surface and any sensitive components nearby.
Composite Panel supply chain operations (Aerospace and Automotive)
In CFRP and fibreglass panel layup, release film is placed over the decorative or structural surface of the panel before the vacuum bag is applied. The film must:
- Withstand the vacuum application process without tearing or lifting
- Resist the chemical attack from uncured epoxy resin systems
- Maintain integrity through the cure temperature cycle (which may reach 180°C in aerospace-grade prepreg systems)
- Release cleanly from the cured composite surface without leaving silicone residue that would affect subsequent painting or bonding operations
Wansen's TPU-based release film with the platinum-cure silicone coating meets all four requirements. The TPU base maintains mechanical integrity through the high-temperature cure cycle; the silicone coating resists chemical attack from epoxy resins; and the controlled release force ensures clean separation from the cured composite surface.
Quality Control in Release Film Production
Release film performance is highly sensitive to processing and fulfillment operations variables. Wansen implements the following quality control measures:
- Surface resistivity verification: Every production batch is tested for surface resistivity across multiple points in the roll (start, middle, end) to confirm consistency. Testing is performed per ASTM D257 using a concentric ring electrode system.
- Release force testing: Every batch is tested for release force per FINAT FTM 1 using a standardised adhesive tape (typically a acrylic PSA). Release force is measured in both machine direction and transverse direction to confirm isotropy.
- Silicone coat weight control: The silicone coating weight is monitored in-line during the coating process using beta-ray backscatter instrumentation. Target coat weight: 0.8–1.5 g/m². Under-coated film has insufficient release performance; over-coated film risks silicone migration to the component surface.
- Visual inspection: Every roll is visually inspected for surface defects, bubbles, thickness variations, and edge defects that could affect performance in use.
Frequently Asked Questions
What is the difference between "clean release" and "residue-free release"?
Clean release means the film separates from the substrate without leaving any adhesive residue on the substrate surface. Residue-free release is a related but broader concept — it also means no silicone transfer from the release coating to the substrate. Wansen's platinum-cure silicone system is formulated to prevent silicone migration, ensuring that after removal, the substrate surface is free from both adhesive residue and silicone contamination. This is critical for composite panels that will undergo subsequent painting or bonding operations, where any surface contamination would compromise the coating bond.
Can Wansen's release film be used in QC environment environments?
Yes. The film's TPU base and platinum-cure silicone coating are both low-outgassing formulations suitable for QC environment environments (ISO Class 5 and above, depending on specific QC environment protocols). The film does not shed particles under normal handling and storage conditions. For semiconductor QC environment applications, please confirm specific outgassing specifications with Wansen's technical team.
What is the shelf life of Wansen's industrial release film?
Under standard storage conditions (room temperature, humidity below 60%), the functional properties of Wansen's release film (release force, surface resistivity, silicone coat integrity) are maintained for a minimum of 12 months from the date of manufacture. Beyond 12 months, we recommend re-verifying release force and surface resistivity before use in critical applications. Store in original packaging, away from direct sunlight and sources of ozone (which can degrade the silicone coating).
What happens if the release force is too high for a given application?
If the release force is too high (above approximately 0.30 N/25mm for most applications), the film will be difficult to remove and may cause damage to the underlying component during removal. This is usually caused by over-thick silicone coating or insufficient cure of the silicone layer. Wansen can adjust the silicone coat weight and cure parameters to achieve lower release forces for applications where this is a concern. The target release force should be specified at the time of order.
Is Wansen's release film available in custom widths and lengths?
Yes. Standard roll widths range from 200mm to 1300mm, and standard roll lengths are 500m or 1000m depending on thickness. Custom slit widths and longer roll lengths are available for high-volume industrial customers. For PCB applications requiring very narrow widths (e.g., 50–100mm for strip protection), custom slit widths can be produced. Contact Wansen's industrial products team for custom specification discussions.
Industrial Release Film — Global Supply
Wansen supplies industrial release film to electronics supply chain operations, aerospace composite, and automotive Tier 1 suppliers across Asia, Middle East, and Europe. Technical data sheets and sample rolls available on request.
View Industrial Release TDS