Custom thickness Mylar sheets are widely used as thin Insulation Materials, protective films, separators, barriers, gaskets, spacers, and custom die-cut components across electrical, electronic, battery, automotive, industrial, and consumer product applications.
The term Mylar sheet is commonly used in the market to describe polyester film, particularly PET polyester film. However, not every thin polymer insulation sheet marketed as a “Mylar sheet” is made from PET. Polycarbonate, polyimide, PEN, and other engineering films may also be selected for specialized insulation applications.
For this reason, material identification is an important part of product selection. When an application requires specific thermal performance, impact resistance, flame resistance, flexibility, dimensional stability, or electrical insulation properties, the actual polymer type and grade should be specified rather than relying only on the general term “Mylar.”
Custom thickness is another important factor. Different electronic and industrial products have different available spaces, electrical requirements, mechanical stresses, and thermal conditions. A 0.05 mm film may be appropriate for a compact insulation barrier, while a 0.3 mm or thicker sheet may be more suitable where additional mechanical support or physical separation is required.
Custom thickness Mylar sheets can also be supplied in different colors, surface finishes, adhesive configurations, shapes, and dimensions. They can be converted by die cutting, punching, slitting, laminating, folding, forming, and other processes.
This makes custom polymer insulation sheets suitable for a broad range of applications, including battery insulation, PCB protection, busbar isolation, electronic component separation, transformer insulation, motor insulation, power supply insulation, EMI/RFI shielding structures, and industrial equipment.
What Is a Custom Thickness Mylar Sheet?
A custom thickness Mylar sheet is a thin polymer film or sheet manufactured or converted to a specified thickness for a particular application.
In conventional terminology, Mylar is associated with PET polyester film. PET film is known for its useful combination of electrical insulation, mechanical strength, dimensional stability, chemical resistance, and processability.
However, engineering applications may require other materials.
A custom insulation sheet can be manufactured from:
PET polyester
PC polycarbonate
PI polyimide
PEN polyethylene naphthalate
PVC
PP polypropylene
PE polyethylene
Other specialty polymer films
Each polymer has different characteristics.
Therefore, “Mylar sheet” should be regarded as a commercial or application term unless the actual material specification is clearly identified.
For critical electrical applications, buyers should confirm:
Polymer type
Material grade
Nominal thickness
Thickness tolerance
Dielectric properties
Thermal performance
Flame rating
Mechanical properties
Surface finish
Adhesive type
Environmental resistance
PET Mylar Sheet ≠ PC Mylar Sheet
PET (Mylar) has a typical temperature resistance of approximately 105–120°C and is relatively brittle, while PC offers higher temperature resistance, better impact strength, and improved resistance to cracking. For lithium battery applications, PC is recommended over PET, especially in areas close to heat sources.
This distinction is important when selecting insulation film for demanding electronic and battery applications.
PET polyester film and PC polycarbonate film are chemically and mechanically different materials.
PET is widely used because it offers good electrical insulation, dimensional stability, tensile strength, and cost efficiency.
PC, on the other hand, can provide excellent impact resistance, formability, and crack resistance.
The appropriate choice depends on the application.
For lithium battery insulation, PC can be advantageous where the insulation component must tolerate bending, forming, mechanical impact, and elevated temperatures.
However, the actual operating temperature, flame classification, electrical requirements, and safety standards should always be evaluated for the complete battery design.
Base Material
Flame-retardant polycarbonate (PC) film is commonly used as the base material for specialized battery and electronic insulation components.
Black is one of the most widely used colors because it provides light blocking, visual consistency, and a clean appearance.
Other colors can also be available, including:
Transparent
Natural
White
Black
Gray
Custom colors
The color selection should not be considered independently from the technical requirements.
For example, transparent PC film may be useful when visual inspection is required, while black PC film can be useful where light blocking or visual separation is desirable.
White film may be selected for applications where a bright surface is useful for inspection or identification.
Surface Finish
A custom PC insulation sheet can be manufactured with different surface finishes.
A commonly used configuration is:
One side with a medium matte texture and one side with a smooth surface.
The matte surface can increase friction between the insulation component and adjacent materials.
In certain assembly configurations, the matte side can face outward to increase friction and help prevent the insulation sheet from shifting during assembly and operation.
Surface texture can also affect:
Adhesion
Friction
Handling
Optical appearance
Printing
Lamination
Forming
Position stability
The surface should therefore be selected according to the final application.
Adhesive Options
Custom thickness insulation sheets can be supplied with different adhesive configurations.
Common options include:
Non-adhesive
The film is supplied without adhesive and can be mechanically installed or positioned within the assembly.
Single-sided adhesive
An acrylic pressure-sensitive adhesive can be applied to one side.
Double-sided adhesive
Adhesive is applied to both sides when the insulation layer must bond between two surfaces.
Adhesive-backed with release liner
The adhesive surface can be protected by a release liner until assembly.
Common adhesive options may include 3M 467 / 468 or domestically produced flame-retardant adhesive materials, depending on application requirements and availability.
The adhesive itself should be evaluated for:
Temperature resistance
Adhesion strength
Aging
Electrical insulation
Flame performance
Chemical resistance
Outgassing
Compatibility with the substrate
The adhesive should not be selected solely based on its initial bonding strength.
Custom Thickness Range
The required thickness depends heavily on the application.
Common thin-film thicknesses may include:
0.05 mm
0.075 mm
0.1 mm
0.125 mm
0.15 mm
0.175 mm
0.2 mm
0.25 mm
0.3 mm
0.38 mm
0.5 mm
0.8 mm
Additional thicknesses may be available depending on the polymer, manufacturing process, and application.
For compact battery and electronic applications, thinner PC film can help save internal space.
For applications requiring stronger physical separation, thicker film may provide better mechanical support.
The correct thickness should be selected based on actual design requirements rather than simply choosing the thickest available material.
Why Custom Thickness Matters
Thickness affects multiple performance characteristics.
A thicker sheet generally provides greater physical separation and can provide increased mechanical rigidity.
A thinner film can occupy less space and may be easier to bend around small components.
Thickness can also affect:
Dielectric performance
Flexibility
Tear resistance
Puncture resistance
Formability
Dimensional stability
Weight
Material cost
Assembly clearance
Therefore, custom thickness is particularly important in compact electronic products.
PC Mylar Sheet for Lithium Battery Applications
PC insulation sheets are increasingly considered for specialized lithium battery insulation applications.
Battery assemblies contain numerous conductive components in close proximity.
These include:
Battery cells
Cell terminals
Busbars
Tabs
BMS components
High-voltage connectors
Relays
Metal housings
End plates
Current collectors
Electrical isolation between these components is essential to prevent unintended contact.
Custom PC insulation sheets can provide physical barriers between conductive surfaces.
Cell Top and Bottom Insulation
For cylindrical and prismatic battery cells, PC insulation sheets can be applied to the positive terminal cap or bottom of the cell.
These parts are often supplied as adhesive-backed die-cut circular or custom-shaped insulation pieces.
They help prevent accidental electrical contact between the battery cell and:
Metal housings
Busbars
Module structures
Conductive Brackets
Other electrical components
Custom die-cut shapes can follow the geometry of the battery cell.
The part may include:
Circular openings
Central holes
Tabs
Notches
Irregular profiles
Adhesive zones
The design should provide sufficient coverage without interfering with the required electrical connection.
Cylindrical Battery Cell Insulation
Cylindrical cells have a compact circular structure.
Insulation components may be required around the top cap, bottom surface, terminals, and other conductive areas.
PC film can be die cut into circular or ring-shaped parts.
The flexible nature of PC film can make it suitable for installation around curved or irregular surfaces.
The exact insulation design depends on the cell architecture.
Prismatic Battery Cell Insulation
Prismatic battery cells generally have larger flat surfaces and metal housings.
Insulation film may be used between the cell housing and surrounding module components.
Custom thickness PC sheets can provide electrical separation without adding unnecessary bulk.
The film can be designed to fit around terminals, tabs, busbars, and mounting structures.
Pouch Cell Insulation
Pouch cells have flexible packaging structures and require careful handling.
Insulation film may be used in selected areas around tabs, module structures, or adjacent conductive components.
Material selection must consider flexibility, puncture resistance, temperature, and compatibility with the pouch-cell assembly.
Module End Plate Insulation
PC insulation sheets can be attached to the inner surfaces of metal end plates at both ends of a battery module.
They help isolate the battery cells and tabs from the metal end plates.
Flame-retardant materials with UL94 V-0 ratings may help improve fire-safety performance and can contribute to delaying the propagation of thermal events, depending on the overall battery design and system-level safety architecture.
The insulation layer can also help prevent mechanical contact between cell structures and metal module components.
High Voltage Area Isolation
PC insulation sheets can be used as insulation barriers or protective covers around:
BMS sensing wires
Battery monitoring terminals
Relays
High-voltage connectors
Busbars
Fuse components
Conductive brackets
Other high-voltage components
These custom insulation barriers help reduce the risk of accidental contact between conductive components.
In high-voltage battery systems, insulation geometry is especially important because the required clearance and creepage distances must be maintained.
BMS Insulation
Battery Management Systems contain sensing wires, connectors, terminals, circuit boards, and communication components.
Custom insulation sheets can protect sensitive areas from contact with conductive structures.
The insulation may be shaped around:
BMS connectors
Sampling terminals
Circuit boards
Busbar connections
Wiring channels
Custom die cutting can improve installation accuracy.
Busbar Insulation
Busbars are conductive components used to distribute electrical current between battery cells or modules.
Because busbars can carry substantial electrical energy, isolation from surrounding conductive structures is important.
Custom PC insulation film can be designed around busbars.
Possible designs include:
Flat barriers
Terminal covers
Insulating rings
Side barriers
Protective overlays
Custom busbar covers
The material thickness should be selected according to the voltage, thermal conditions, mechanical requirements, and safety design.
Relay and Contactor Insulation
High-voltage relays and contactors are used in battery management and power distribution systems.
Insulation barriers can help separate conductive terminals from nearby metal structures.
A custom PC sheet can be designed with holes, slots, and tabs to fit around the component.
PC Mylar Sheet vs Fish Paper
PC film and fish paper (vulcanized fiber insulation paper) have different characteristics and are often used together rather than treated as direct substitutes.
PC film is typically thinner, with common thicknesses of approximately 0.05–0.3 mm. It offers good flexibility, bending resistance, and crack resistance, and can be supplied in transparent, white, or black versions.
Fish paper is generally thicker, commonly ≥0.15 mm, and offers good dielectric strength but is relatively more brittle.
In many battery insulation designs, the two materials can be combined according to their respective characteristics:
PC film: Used for thin, flexible insulation sheets and custom die-cut barriers
Fish paper: Used for thicker insulation pads, spacers, and structural insulating layers
This combination can provide a practical balance between flexibility, electrical insulation, mechanical protection, thickness, and assembly requirements.
Advantages of PC Film Compared With Fish Paper
PC film can offer several advantages for applications requiring flexible insulation.
Its flexibility can make it easier to install around curved or irregular structures.
Its impact resistance can also be beneficial in assemblies exposed to mechanical handling or vibration.
PC film can be produced in thinner gauges, helping reduce overall component thickness.
Transparent PC film can also allow visual inspection of the underlying structure.
Fish paper remains useful where a thicker, rigid, or traditional electrical insulation component is required.
The two materials therefore serve different functions.
Custom Die Cut Insulation Sheets
Custom die cutting is one of the most common conversion methods for polymer insulation film.
A die-cut insulation part can be manufactured to match the exact geometry of an electronic component.
Common features include:
Holes
Slots
Tabs
Notches
Curved edges
Rounded corners
Internal openings
Asymmetrical profiles
Custom die cutting can improve assembly efficiency and repeatability.
Die Cut Battery Insulation
Battery insulation parts are often produced using precision die cutting.
Examples include:
Cell top insulation rings
Cell bottom insulation sheets
Terminal barriers
Busbar insulation
End plate insulation
BMS insulation
Connector barriers
High-voltage insulation covers
The design can be optimized to reduce material waste and simplify installation.
Custom Shape and Size
Custom thickness is only one part of the customization process.
The overall dimensions can also be customized.
A customer may specify:
Length
Width
Diameter
Hole size
Hole location
Corner radius
Slot dimensions
Tab dimensions
Adhesive area
Tolerance
CAD drawings can help ensure accurate conversion.
Round Insulation Sheets
Round insulation sheets are frequently used for battery cells, terminals, screws, and other circular components.
They can be manufactured with or without central openings.
Adhesive-backed versions can simplify positioning during assembly.
Ring Insulation Parts
Ring-shaped insulation parts are useful around terminals and mounting hardware.
The internal opening allows the conductive component to pass through while the surrounding polymer provides electrical separation.
Rectangular Insulation Sheets
Rectangular insulation sheets are commonly used for:
PCBs
Battery modules
Metal housings
End plates
Electrical panels
Power supplies
Custom holes and slots can be added according to the assembly design.
Irregular Insulation Components
Many electronic products have irregular internal geometry.
Custom die cutting allows insulation components to match complex shapes.
This can reduce unnecessary overlap and improve space utilization.
Matte and Smooth Surfaces
A two-sided surface structure can provide different functions on each side.
A medium matte side can provide increased friction.
A smooth side may be useful for contact with another component, adhesive, printing, or lamination.
Surface texture can influence the coefficient of friction and assembly behavior.
Black PC Insulation Film
Black PC film is widely used in electronic and battery insulation applications.
Advantages may include:
Light blocking
Professional appearance
Easy visual identification
Good contrast against metallic components
Reduced visibility of internal structures
Black is particularly common in battery module applications.
Transparent PC Insulation Film
Transparent PC film allows the underlying component to remain visible.
This can be beneficial when inspection is important.
Transparent insulation film may also be selected for display systems, sensors, electronic modules, and other applications where visibility is useful.
White PC Insulation Film
White PC film can provide a bright surface that may simplify visual inspection.
It can also be useful when color identification is part of the assembly process.
Flame Retardant PC Film
Flame-retardant PC film is designed for applications where flame behavior is an important consideration.
In battery and electronic systems, flame resistance can contribute to overall safety design.
A material marketed as flame retardant should be evaluated according to its applicable test standard and grade.
For example, UL94 classifications are commonly referenced in polymer flame testing.
A UL94 V-0 classification should be confirmed from appropriate material documentation rather than assumed based on product description alone.
Thermal Performance
Thermal performance is one of the most important factors when choosing insulation film.
Electronic components can generate heat during normal operation.
Battery systems can also experience elevated temperatures during charging, discharging, or abnormal operating conditions.
PC film may be considered where improved temperature performance and mechanical durability are required.
The actual temperature capability should always be based on the specific PC grade and tested operating conditions.
Temperature Resistance
Temperature resistance is not a single fixed value for all polymer films.
Actual performance depends on:
Polymer chemistry
Grade
Thickness
Duration
Mechanical loading
Environmental conditions
Electrical stress
Therefore, material datasheets and application testing should be used when defining maximum operating temperatures.
Mechanical Strength
Mechanical strength is important for insulation sheets that are installed during automated or manual assembly.
The material may be subjected to:
Bending
Folding
Punching
Compression
Vibration
Impact
Handling
PC film offers good impact resistance and can be useful in applications where crack resistance is important.
Crack Resistance
Cracking can compromise the coverage and protective function of an insulation component.
A cracked insulation film may expose conductive areas.
PC is generally known for good impact resistance and toughness.
This can be beneficial when the insulation component experiences bending or mechanical stress.
Formability
Formability is particularly useful for custom insulation parts.
A formable material can follow the shape of a battery cell, terminal, bracket, housing, or other component.
Custom forming can reduce gaps and improve coverage.
Dimensional Stability
Dimensional stability refers to the ability of the material to maintain its intended dimensions when exposed to temperature changes or environmental conditions.
Good dimensional stability is important for precision electronic assemblies.
If an insulation component changes dimensions excessively, it may move, shrink, expand, or interfere with adjacent components.
Electrical Insulation
The primary purpose of many custom insulation sheets is to electrically isolate conductive components.
Important electrical characteristics may include:
Dielectric strength
Insulation resistance
Surface resistance
Breakdown voltage
Arc resistance
Actual performance depends on material thickness and environmental conditions.
Dielectric Strength
Dielectric strength describes the electrical stress a material can withstand before dielectric breakdown occurs.
Increasing film thickness can influence the overall insulation capability, although thickness alone does not determine complete system safety.
Testing should be performed under conditions representative of the final application.
Insulation Resistance
Insulation resistance indicates how effectively a material resists electrical current leakage.
High insulation resistance can be desirable for battery systems, power electronics, circuit boards, and electrical equipment.
Temperature and humidity can influence measured insulation resistance.
Electrical Clearance and Creepage
Insulation design must consider both clearance and creepage.
Clearance is the shortest distance through air between conductive components.
Creepage is the shortest distance along an insulating surface.
Custom die-cut insulation should not unintentionally reduce the required distances.
The required values depend on voltage, pollution level, product standard, and application architecture.
EMI and RFI Shielding Applications
Custom insulation film can also be combined with conductive foil for electromagnetic shielding.
A polymer film laminated with metal foil can provide:
Electrical insulation
EMI shielding
RFI shielding
Mechanical separation
Surface protection
The polymer layer can electrically isolate the conductive foil from surrounding components.
The conductive layer provides the electromagnetic shielding function.
Metal Foil Laminated PC Film
PC film can be laminated with conductive materials in certain applications.
Potential conductive layers include:
Aluminum foil
Copper foil
Other conductive films
The final laminate can be converted into custom shapes.
This can be useful in electronics where insulation and shielding are required in the same component.
Power Supply Insulation
Power supplies contain multiple electrical components operating at different voltage levels.
Custom insulation sheets can separate:
Transformers
Circuit boards
Heat sinks
Terminals
Metal housings
Conductive brackets
The material must be selected according to electrical and thermal requirements.
PCB Insulation
Printed circuit boards often require isolation from metal enclosures and mounting structures.
A custom PC or PET insulation sheet can be positioned underneath or around a PCB.
The shape can include mounting holes and connector openings.
Transformer Insulation
Transformers require insulation between windings and conductive structures.
Insulation films can serve as barriers, separators, and protective layers.
The material should be selected according to voltage, thermal class, mechanical requirements, and relevant safety standards.
Motor Insulation
Motors contain coils, windings, metal structures, and moving components.
Insulation film can be used in selected applications where electrical separation and mechanical protection are required.
Thermal performance is particularly important for motor insulation.
Automotive Electronics
Automotive electronics are exposed to:
Temperature changes
Vibration
Humidity
Electrical loads
Mechanical shock
Chemicals
Custom insulation sheets can help isolate electronic components and protect conductive structures.
Battery systems, control modules, power electronics, connectors, and wiring assemblies may all require specialized insulation components.
EV Battery Insulation
Electric vehicle battery packs contain hundreds or thousands of electrical interfaces depending on architecture.
Custom insulation components can be used at cell, module, and pack levels.
Applications can include:
Cell insulation
Terminal insulation
Busbar insulation
Module insulation
End plate insulation
BMS insulation
High-voltage barrier insulation
Material selection should be performed at the system level.
Energy Storage Battery Insulation
Energy storage systems also require electrical separation between cells and conductive structures.
Custom PC insulation sheets can be used in selected stationary battery systems.
The required properties depend on the voltage, temperature, enclosure design, and safety requirements.
Industrial Electrical Insulation
Industrial equipment may require insulation components capable of continuous operation.
Applications include:
Control panels
Motors
Power supplies
Industrial controllers
Switchgear
Sensors
Electrical cabinets
Power distribution systems
Custom thickness can be selected according to the specific mechanical and electrical requirements.
Consumer Electronics
Thin insulation film is widely applicable to compact consumer electronics.
Potential applications include:
Mobile devices
Computers
Displays
Printers
Household electronics
Portable electronics
Chargers
Power adapters
Thin custom components can help maintain compact internal layouts.
Display Applications
Displays often contain metal frames, circuit boards, connectors, and conductive components.
Custom insulation film can isolate these structures.
Transparent or black film may be selected depending on the design.
Connector Insulation
Connectors contain closely spaced conductive terminals.
Custom insulation barriers can reduce the risk of unintended electrical contact.
The insulation component must be designed without interfering with connector engagement.
Terminal Insulation
Terminal areas are common locations for custom insulation components.
A die-cut film can be positioned around a terminal while leaving the required conductive connection exposed.
Adhesive-Backed Insulation
Adhesive-backed insulation simplifies installation.
The adhesive holds the part in its intended position during assembly.
This is especially useful for:
Battery cell insulation
Busbar barriers
PCB insulation
Metal housing insulation
Terminal barriers
The adhesive should be compatible with the operating environment.
Acrylic PSA for Insulation Applications
Acrylic pressure-sensitive adhesive is commonly used for adhesive-backed insulation films.
Important adhesive properties include:
Initial tack
Peel strength
Shear strength
Temperature resistance
Aging resistance
Chemical resistance
Electrical insulation
Flame resistance
The adhesive layer is part of the complete insulation system and should be evaluated accordingly.
Release Liner
Adhesive-backed insulation components are often supplied with a release liner.
The liner protects the adhesive surface before installation.
It can be removed immediately before assembly.
For automated production, liner selection can also influence handling and dispensing.
Custom Thickness for Different Applications
Different applications may require different film thicknesses.
Thin films are often preferred where:
Space is limited
Flexibility is important
Weight reduction is important
Complex forming is required
Thicker films may be preferred where:
Mechanical protection is required
Greater physical separation is needed
Puncture resistance is important
Additional rigidity is desirable
There is no universally optimal thickness.
Thin 0.05 mm PC Insulation Film
Very thin PC film can be useful for compact insulation applications.
Potential uses include:
Battery terminal barriers
Thin electronic separators
Compact PCB insulation
Small component insulation
Because thin films are lightweight and flexible, they can fit into narrow spaces.
0.1 mm Insulation Film
0.1 mm film provides a balance between thin construction and mechanical handling.
It can be used for various electronic insulation applications.
The final electrical performance should be verified for the specific material.
0.2 mm Insulation Film
0.2 mm film provides additional thickness compared with very thin films.
It may be selected where greater mechanical durability or physical separation is required.
0.3 mm PC Film
0.3 mm PC film is commonly considered for applications requiring a more robust insulation barrier.
It can provide greater stiffness while remaining relatively easy to convert into custom shapes.
Thickness Above 0.3 mm
Thicker polymer sheets can be used where structural support, mechanical protection, or greater physical separation is needed.
However, increasing thickness can reduce flexibility and increase material usage.
The optimal thickness should therefore be determined from actual requirements.
Custom Die Cutting and Tooling
Custom tooling can be developed according to the part geometry.
A customer may provide:
CAD drawings
Engineering drawings
PDF drawings
Physical samples
Dimensioned sketches
The tooling design can then be developed around the required geometry.
For large-volume projects, tooling costs can often be distributed across the production quantity.
Free Tooling and Mold Development
For qualifying custom orders, free tooling and mold development may be available.
This depends on:
Part complexity
Production volume
Material
Tooling type
Manufacturing requirements
Large-volume projects may benefit from more favorable tooling economics.
Large Volume Production
Large-volume production can be supported by:
Precision die cutting
Rotary die cutting
Automated inspection
Roll processing
Continuous slitting
Automated packaging
Production efficiency can help reduce unit cost.
Small Volume and Prototype Production
Prototype and small-volume projects may use alternative cutting methods.
These can include:
Flatbed die cutting
CNC cutting
Laser cutting
Manual sample cutting
The appropriate method depends on the part geometry and material.
Quality Control
Quality control is essential for custom insulation parts.
Inspection may include:
Thickness
Dimensions
Hole position
Part shape
Surface finish
Adhesive position
Material identification
Visual appearance
Edge quality
Quantity
Electrical and thermal testing may also be required for critical applications.
Thickness Tolerance
Nominal thickness does not represent the complete specification.
Thickness tolerance should also be defined.
For example, an engineering specification may identify:
Nominal thickness: 0.20 mm
The actual acceptable range must then be established based on the material and application.
Tighter tolerances may require more advanced production and inspection.
Dimensional Tolerance
Custom die-cut parts may require controlled tolerances.
Important dimensions can include:
Outside diameter
Inside diameter
Overall length
Overall width
Hole diameter
Hole location
Slot width
Corner radius
Tolerance requirements should be based on actual assembly needs.
Edge Quality
Clean edges are important for insulation components.
Poorly cut edges can cause:
Burrs
Deformation
Loose particles
Reduced dimensional accuracy
For electronic and battery applications, clean cutting can improve assembly reliability.
Surface Cleanliness
Battery and electronic assemblies can be sensitive to contamination.
Insulation sheets should be protected from:
Dust
Oil
Grease
Metal particles
Adhesive contamination
Packaging and handling procedures should reflect the cleanliness requirements of the application.
Packaging
Custom insulation sheets can be supplied in different formats.
Potential packaging includes:
Individual pieces
Stacks
Sheets
Rolls
Reels
Trays
Release liners
Protective bags
The appropriate format depends on the assembly process.
Automated Assembly
Custom insulation components can be designed for automated placement.
Consistent part dimensions are important for automated handling.
Adhesive-backed components can be supplied on release liners or reels where suitable.
Manual Assembly
For manual assembly, easy-to-handle insulation components can improve productivity.
Tabs, liners, and custom shapes can make positioning easier.
Design Considerations
When designing a custom thickness insulation sheet, engineers should consider:
Material type
Thickness
Operating temperature
Voltage
Required dielectric strength
Mechanical stress
Surface finish
Adhesive requirements
Environmental exposure
Required dimensions
Tolerances
Production volume
A complete specification reduces manufacturing uncertainty.
Common Applications
Custom thickness polymer insulation sheets can be used for:
Lithium batteries
EV batteries
Energy storage batteries
BMS systems
Busbars
PCBs
Power supplies
Transformers
Motors
Displays
Televisions
Computers
Connectors
Relays
Contactors
Industrial electronics
Automotive electronics
Consumer electronics
EMI shielding
RFI shielding
Advantages of Custom Thickness Mylar Sheets
Custom thickness insulation sheets offer several advantages.
Thin film can fit into compact electronic assemblies.
Die cutting allows complex shapes.
Polymer film can provide separation between conductive components.
The film can protect components from unwanted contact and abrasion.
Thin polymer film adds relatively little weight.
The material can be die cut, laminated, adhesive coated, slit, or formed.
Different colors can support product appearance and identification.
Adhesive-backed configurations can simplify assembly.
The same design can often be produced from prototype quantities through high-volume production.
Material Selection Guide
Selecting between PET, PC, and other polymer films requires a clear understanding of the application.
PET may be suitable when cost efficiency, electrical insulation, dimensional stability, and conventional polyester film performance are sufficient.
PC may be preferred when impact resistance, toughness, formability, and crack resistance are more important.
Polyimide may be considered for higher-temperature applications.
PEN may be considered when a combination of thermal and mechanical properties beyond conventional PET is required.
The correct choice depends on the application and material specification.
PET Insulation Film
PET polyester film is widely used in electrical insulation.
It offers:
Good tensile strength
Good electrical insulation
Dimensional stability
Chemical resistance
Good processability
Cost efficiency
However, it should not automatically be substituted for PC in applications requiring higher toughness or specific forming performance.
PC Insulation Film
PC polycarbonate film provides:
High impact resistance
Good toughness
Good formability
Crack resistance
Useful dimensional stability
Potential flame-retardant grades
It can be particularly useful for custom die-cut insulation parts.
Fish Paper Insulation
Fish paper is a traditional electrical insulation material.
It can offer:
Good dielectric strength
Mechanical rigidity
Electrical insulation
Traditional battery and motor insulation applications
However, it is generally less flexible than PC film.
Combining PC Film and Fish Paper
PC film and fish paper can complement each other.
PC can provide thin flexible insulation.
Fish paper can provide thicker structural insulation.
A battery assembly may therefore use both materials in different locations.
The choice depends on electrical, mechanical, thermal, and dimensional requirements.
Custom Thickness Mylar Sheets for Battery Manufacturers
Battery manufacturers often need insulation components designed around specific cell and module architectures.
Custom thickness and custom geometry can improve component fit.
Common requirements include:
Exact thickness
Die-cut shape
Adhesive backing
Flame retardancy
High-temperature stability
Electrical insulation
Clean edges
Consistent dimensions
Custom Thickness Mylar Sheets for Electronic Devices
Electronic devices often have limited internal space.
Custom thickness film allows designers to select an appropriate balance between insulation and package size.
This is particularly useful for compact power supplies, displays, control boards, communication devices, and consumer electronics.
Custom Thickness Mylar Sheets for Industrial Equipment
Industrial equipment can require durable insulation barriers.
Custom PC or PET sheets can be designed to withstand mechanical handling and environmental exposure.
Applications can include electrical cabinets, motors, power equipment, controllers, and industrial automation systems.
Custom Thickness Mylar Sheets for Automotive Applications
Automotive electronics require materials capable of handling vibration and temperature variation.
Custom insulation sheets can be used in battery packs, control modules, connectors, sensors, and power electronics.
The exact material should be qualified for the intended automotive environment.
Conclusion
Custom Thickness Mylar Sheet for Various Applications is a broad category covering polymer film insulation products used in electronics, batteries, electrical equipment, automotive systems, industrial equipment, and consumer products.
Although the term “Mylar sheet” is commonly associated with PET polyester film, engineering applications should distinguish clearly between PET Mylar film and PC polycarbonate film.
PET (Mylar) has a typical temperature resistance of approximately 105–120°C and is relatively brittle, while PC offers higher temperature resistance, better impact strength, and improved resistance to cracking. For lithium battery applications, PC is recommended over PET, especially in areas close to heat sources.
Flame-retardant PC film can be supplied in black, transparent, white, and other colors. A medium matte surface on one side and a smooth surface on the other can provide different functional characteristics. The matte side can be positioned outward to increase friction and help reduce movement during assembly.
Custom adhesive configurations can include non-adhesive, single-sided acrylic PSA, and double-sided adhesive, with release liners available for adhesive-backed versions. Adhesive options may include 3M 467 / 468 or other suitable flame-retardant adhesive systems according to application requirements.
PC insulation film has several potential applications in lithium batteries. It can be used for cell top and bottom insulation, module end plate insulation, busbar isolation, BMS protection, high-voltage barriers, relay insulation, connector insulation, and other custom die-cut battery insulation parts.
PC film and fish paper are not identical materials. PC is generally thinner and more flexible, while fish paper is typically thicker and more rigid. They can be used together to achieve a balance between flexibility, electrical insulation, mechanical protection, thickness, and assembly requirements.
The most important principle is that material selection should be based on actual application requirements rather than the generic term “Mylar.” Engineers should evaluate polymer type, thickness, thermal performance, dielectric properties, flame rating, mechanical strength, surface finish, adhesive compatibility, dimensions, tolerance, and environmental conditions.
With appropriate material selection and precision conversion, custom thickness insulation sheets can provide reliable electrical isolation, mechanical protection, efficient assembly, and compact product design across a wide range of modern electronic and electrical applications.
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