Metal film materials primarily consist of thin metallic materials such as aluminum foil, copper foil, and stainless steel foil, and are widely used in applications including electronic thermal conductivity, electromagnetic shielding, flexible circuitry, and packaging composites. The surfaces of these materials are dense and smooth, often featuring a passivation layer, stamping-induced oil contamination, or an oxide layer; consequently, conventional adhesives struggle to achieve long-term, stable bonding performance. In industrial settings, it is essential to select appropriate adhesive types based on the composite substrate and the specific operating conditions.
I. Core Requirements for Adhesion of Metal Film Materials Metal bonding adhesive selection for thin films follows the same surface preparation logic, and JOME supplies grades for metal foil and film assemblies.
Excellent interfacial adhesion: ensures full wetting of the metal surface, preventing delamination or peeling over extended periods of use.
Weather and temperature resistance: Designed for high-temperature operating conditions during fabrication and service, and certified to pass reliability tests such as the Double 85 test.
Compatible with mass production processes: enables uniform film formation and is compatible with roll-to-roll production techniques such as roller coating and blade coating.
No corrosion risk: The formulation contains no corrosive components such as strong acids or bases, thereby preventing oxidation and discoloration of the metal coating, as well as degradation of its performance.
II. Types of Mainstream Compatible Adhesives
1. Liquid-modified hot-melt adhesive
This adhesive is predominantly used for large-area coating applications; it can be pre-applied to substrates such as PET or PI, and after activation under high temperature and pressure, forms a robust bond with the metal film. Once the adhesive layer is fully cured, it exhibits high bonding strength and outstanding resistance todamp heat aging, making it well-suited for roll-to-roll continuous mass production. Consequently, it is the preferred adhesive choice for electromagnetic shielding films and thermally conductive composite films. Certain silicone-modified variants offer controllable initial tack; after coating and winding, placement at room temperature allows the initial tack to dissipate automatically, facilitating long-term storage of the film rolls.
2. Two-component polyurethane adhesive
This material is suitable for structural metal film bonding applications, where it cures via chemical reactions to achieve high cohesive strength, as well as excellent resistance to hydrolysis and extreme temperature conditions. It is ideal for structural composites between thick metal foils and plastic or foam materials, and is widely used in thermal conductive components for power batteries and automotive electronics; however, its curing cycle is relatively long, necessitating the integration of a curing process step.
3. Acrylate pressure-sensitive adhesive
This product is primarily used for temporary protective self-adhesive metal film applications. It can achieve adhesion under mild pressure at room temperature, offering ease of use, and leaves no residual adhesive after peeling. It is suitable for surface protective films on metal foils and for temporary masking in manufacturing processes; however, its temperature resistance and long-term adhesive strength are inferior to those of hot-melt adhesives, making it unsuitable for prolonged operation in high-temperature environments.
4. Epoxy structural adhesive
For high-strength metal-to-metal film bonding applications, the cured adhesive layer exhibits high hardness, high shear strength, and excellent chemical corrosion resistance. It is widely used for securing metal films in precision electronic components; however, the adhesive layer is relatively brittle and not suitable for repeated bending, making it inappropriate for flexible film composite applications.
Selection Reference
For mass production of flexible film materials, modified hot-melt adhesives are preferred due to their high production efficiency and stable performance; for bonding structural components, two-component polyurethane adhesives or epoxy adhesives may be selected; for temporary protective applications, acrylic pressure-sensitive adhesives are suitable. Prior to application, it is recommended to clean the metal film surface of oil residues and contaminants to ensure optimal bonding performance.
product recommendation
Product Name: JOMP1518K Modified Hot-Melt Adhesive
Product Introduction: Silicone-modified polyurethane hot-melt adhesive, applicable to substrates such as PET and PI, and suitable for high-temperature hot-pressure bonding of metal film materials.
Product Features: After coating and curing, the material exhibits initial tack; when left at room temperature, this initial tack is eliminated. It offers strong adhesion and is compatible with a wide range of substrates.
Application: High-temperature hot-press bonding of various materials (e.g., PET, PI) and metal film materials
Why is it difficult to bond metal film materials?
Metal film materials, owing to their properties such as thinness, electrical conductivity, barrier properties, and thermal conductivity, are widely used in fields including electronics, packaging, and new energy applications. However, they remain widely recognized as difficult-to-bond materials in industrial bonding processes, frequently exhibiting issues such as delamination, peeling, and insufficient bonding strength. The challenges in bonding these materials do not stem from a single factor, but rather result from the combined effects of multiple inherent characteristics—namely, the material structure, interfacial conditions, and stress matching.
The metal film layer is ultra-thin with a smooth surface, resulting in extremely poor mechanical anchorage.
Metal films are typically nanoscale ultra-thin coatings, with a thickness accounting for less than 0.1% of the total thickness of the substrate. Their surfaces are extremely smooth, exhibiting virtually no micro-textural features; consequently, adhesives cannot establish mechanical interlock or physical anchorage. Also, processing techniques such as vacuum evaporation can easily result in uneven film thickness, which further compromises the uniformity of interfacial bonding, leading to localized failure of the adhesive bond.
The interface exhibits numerous defects, making chemical bonding difficult to stabilize.
When a metal film is exposed to air, it rapidly forms a porous oxide layer; this layer exhibits weak adhesion to the metal substrate, and even if the adhesive successfully adheres to the oxide layer, it may detach along with the entire oxide layer under mechanical stress. Also, slip agents present in substrates such as PET or PI can migrate to the surface of the metal film. When combined with contaminants like grease and moisture, this migration significantly reduces the surface energy of the metal film, preventing the adhesive from fully wetting the interface and hindering the formation of effective intermolecular forces.
Incompatibility in the coefficient of thermal expansion can lead to interfacial stresses that compromise the bond strength.
The coefficients of thermal expansion (CTE) between metals and conventional adhesives or polymer substrates differ significantly; consequently, shear and tensile stresses develop at the interface during temperature fluctuations. Under prolonged thermal cycling or high-temperature operating conditions, the continuous accumulation of these stresses can lead to cracking of the adhesive layer and interfacial debonding—these phenomena constitute one of the primary causes of long-term bonding failure in metallic film materials.
Conventional adhesives exhibit insufficient compatibility.
Conventional adhesives struggle to simultaneously satisfy the ultra-thin characteristics, surface inertness, and high-temperature operating requirements of metal films; they either exhibit insufficient initial tack or fail to maintain durable adhesion after curing, thereby failing to meet the industrial bonding requirements for metal film composites.
In summary, the bonding challenges associated with metallic film materials arise from the combined effects of ultra-thin structures, interfacial defects, stress mismatch, and inadequate compatibility of the adhesives; therefore, the use of specialized modified adhesives is required to achieve reliable bonding.
product recommendation
Product Name: JOMP1518K Modified Hot-Melt Adhesive
Product Introduction: Silicone-Modified Polyurethane Liquid Hot-Melt Adhesive
Product Features: Strong adhesion to metal film materials; suitable for large-area coating applications.
Application: Suitable for high-temperature hot-press bonding of various metal film materials using PET, PI, and other materials.
The full JOME product catalogue named above is one part of the JOME production line. For the earlier discussion of Which materials can be bonded using liquid, follow the link, or browse the Shanghai JOME Industrial range; specifications and samples go through the consult the JOME technical team.