Xuchang Chengrui Insulation Materials Co., Ltd.
Henan Province, China
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Ever wondered what keeps your smartphone from overheating or satellites intact in space? Meet polyimide film – the unsung hero of extreme environments. This golden-brown material isn’t plastic, though it looks deceptively simple. Born from combining aromatic dianhydrides and diamines, it’s like a molecular fortress. What sets it apart? Imagine a material that laughs off flames (-269°C to +400°C), scoffs at harsh chemicals, and still stays flexible. From NASA engineers to circuit board designers, pros rely on this film where ordinary materials fail. It’s not just heat-resistant – it’s practically indestructible, maintaining strength whether in Arctic cold or rocket engine heat. Next time your car’s electronics survive a summer heatwave, you’ll know who to thank.
Below are the Polyimide Film Types for your reference.
1. Standard Kapton-Type Films
l Base grade with balanced thermal/electrical properties
l Typical thickness: 12.5-125μm
l Key specs:
• 200°C continuous service temperature
• Dielectric strength ≥200kV/mm
• Tensile strength ≥200MPa2. Filled Composite Films
l Enhanced versions with additives:
• Graphite-filled (improved thermal conductivity)
• Silica-filled (reduced CTE for semiconductor use)
• Mica-reinforced (higher voltage endurance)3. Specialty Variants
l Adhesive-backed films:
¡ Pre-applied silicone or acrylic adhesives
¡ Used in motor insulation systems
l Conductive films:
¡ Carbon-loaded (10⁴-10⁶Ω/sq surface resistance)
¡ Metal-clad versions (aluminum/copper laminated)
l Transparent films:
¡ 85-90%, light transmission (display applications)
¡ UV-resistant formulations
4. Advanced Modified Polyimides
l Low-CTE films (≤10ppm/K) for flexible electronics
l High-Tg versions (400°C+) for aerospace
l Hydrolysis-resistant grades for humid environments
1. Electronics Manufacturing
l Flexible printed circuits (FPCs): Withstands solder reflow at 260°C
l Chip packaging: Low thermal expansion prevents die stress
l High-frequency boards: Stable dielectric properties up to 10GHz
2. Electrical Insulation Systems
l Motor slot liners: Survives Class H (180°C) environments
l Transformer barriers: Resists oil degradation for 30+ years
l Spacecraft wiring: Passes NASA outgassing standards
3. Industrial Processing
l Heater insulation: Maintains strength at 400°C continuous
l Plasma etching masks: Endures corrosive semiconductor processes
l Laser ablation substrates: Precise patterning without melting
Emerging Applications
l EV battery separators: Prevents thermal runaway propagation
l 5G antenna substrates: Low loss tangent at millimeter waves
l Medical implant coatings: Biocompatible and sterilizable
Picture a construction crew for microelectronics – that’s polyimide tape. When circuit boards get wave soldered, this amber tape acts as a thermal bodyguard, protecting delicate components from molten metal. Repairing frayed motor windings? It’s the electrician’s best friend, insulating better than regular tapes without adhesive meltdowns. In 3D printing, makers use it as a build plate liner for perfect first layers. But here’s the kicker – NASA wraps satellite joints with it because unlike duct tape, it won’t outgas in vacuum. Even your hair stylist might use it – some high-end hair straighteners have polyimide tape layers for heat distribution. It’s the MacGyver of high-performance adhesives.
Five words: Thermal superhero with memory. Unlike materials that warp under heat, polyimide films “remember” their shape – crucial for precision parts. Their CTE (thermal expansion rate) matches metals, preventing connector failures in gadgets. The real magic? They repel almost everything – oils, acids, solvents – while staying electrically neutral. Need numbers? How about 500°V/mil dielectric strength – enough to stop lightning in its tracks. Yet they bend like gymnasts (3%, elongation) without cracking. Transparent to microwaves but opaque to UV, they’re the Swiss Army knife of material properties. Oh, and they’re lighter than aluminum foil despite being 10x stronger than steel pound-for-pound.
1. Thermal Performance
l Continuous service temperature: -269°C to +400°C
l UL 94 V-0 flame rating standard
l Only 1-2%, dimensional change at 300°C
2. Electrical Properties
l Dielectric constant: 3.4 (1kHz)
l Volume resistivity: 10^17 Ω·cm
l Withstands >20kV/mm breakdown voltage
3. Mechanical Advantages
l Tensile modulus: 2.5-3.5 GPa
l Tear propagation resistance: >100 N/mm
l Maintains flexibility after 100,000+ flex cycles
4. Chemical Resistance
l Impervious to solvents, oils, and acids
l Hydrolysis resistance >500hrs at 85°C/85%, RH
l UV stability with <5%, property loss after 2000hrs exposure
5. Manufacturing Consistency from Top Chinese Suppliers
l Thickness tolerance: ±3%, (vs. industry ±5%,)
l Surface roughness: <0.1μm Ra
l Roll-to-roll uniformity: <2%, variation
6. What is Polyimide Film Benefits?
For global importers sourcing high-performance insulation materials, polyimide film delivers unmatched advantages that justify its premium price. These ultra-thin yet durable polymer sheets have become indispensable in modern electrical engineering due to three core benefits:
1. Extreme Environment Reliability
l Maintains mechanical integrity from -269°C to +400°C
l Only 2-3%, dimensional change across temperature extremes
l Outperforms competitors in thermal cycling tests
2. Electrical Insulation Superiority
l Dielectric strength remains stable at 200+ kV/mm even after thermal aging
l Surface resistance exceeds 10¹⁶ ohms in humid conditions
l Minimal dielectric loss (tanδ < 0.002) at high frequencies
3. Manufacturing Process Advantages
l Available in thicknesses from 7.5μm to 125μm with ±1μm tolerance
l Customizable with adhesives or metal coatings
l Chinese producers now offer cost-effective solutions without quality compromise
For flexible circuit manufacturers and transformer producers, these characteristics translate to: • 30%, longer product lifecycles in harsh environments • Reduced warranty claims from insulation failures • Design flexibility for compact, high-power devices
Leading Chinese manufacturers achieve these benefits through:
l Advanced imidization control technology
l Japanese-grade PMDA raw materials
l Class 1000 cleanroom production
Bottom line? Polyimide pays you back. Factories love slashing energy costs – no need for protective coatings means faster production. For product designers, it’s freedom: make devices thinner, lighter, yet tougher. Maintenance crews sleep better knowing insulation won’t degrade over decades. Environmentally? It’s the quiet green warrior – longevity reduces waste, and some types are now recyclable. In medical implants, its biocompatibility avoids rejection risks. Cost-wise, while pricier upfront than PVC, its 50,000-hour lifespan in motors makes accountants smile. Most importantly, it enables technologies we thought impossible – from foldable displays to deep-sea sensors.
7. What is Polyimide Film Function?
At its core, polyimide film is the ultimate mediator. In flexible circuits, it separates copper traces while conducting heat away. As a release liner, it lets sticky adhesives peel cleanly. In harsh environments, it’s both shield and bridge – blocking corrosive chemicals while letting electrical signals pass unimpeded. For coatings, it converts from liquid to protective armor under heat. Its porosity can be tuned – dense for insulation, micro-porous for filtration membranes. Some even use it as a molecular sieve in gas separation. But perhaps its greatest trick? Enabling innovation – without it, your smartwatch would be a bulky brick, and Mars exploration would’ve stayed sci-fi.
8. What is Polyimide Film Advantages?
Polyimide film isn’t called the “gold standard” of high-performance materials for nothing. Imagine a shield that deflects heat, chemicals, and electricity while bending like paper. Aerospace engineers lean on it because it won’t melt near jet engines or crack in space’s frigid void. Electronics manufacturers save millions by using it as a circuit base – no need for bulky cooling systems. Its secret? A rare combo of thermal stability (-269°C to +400°C) and electrical insulation (up to 10⁹ Ω·cm). Unlike metals, it doesn’t corrode; unlike plastics, it won’t warp under soldering irons. Even better, it’s lightweight – 1.4 g/cm³ – making EVs and drones faster. From medical implants to 5G antennas, polyimide solves problems other materials can’t touch.
Advantages Summary Table
Feature | Polyimide Film | Common Alternatives |
Temperature Range | -269°C to +400°C | -50°C to 150°C (PVC) |
Dielectric Strength | 500-700 V/mil | 300-400 V/mil (PET) |
Chemical Resistance | Resists acids, fuels | Degrades (Rubber) |
Weight | 1.4 g/cm³ | 2.7 g/cm³ (Aluminum) |
9. What is Polyimide Film Disadvantages?
Even superheroes have kryptonite. Polyimide film’s Achilles’ heel? Cost. Producing it involves pricey monomers and high-temperature curing – think 300°C ovens guzzling energy. Color options are limited too; that iconic amber hue clashes with sleek tech designs. While flexible, it’s brittle when folded sharply – a headache for foldable phone makers. Recycling? Most types can’t be melted down, ending up in landfills. Adhesion issues plague manufacturers – special primers are needed before printing circuits. Worst of all, certain grades release toxic fumes when burned, complicating disposal. For all its brilliance, polyimide isn’t a one-size-fits-all solution.
Disadvantages Summary Table
Issue | Impact | Workaround |
Production Cost | 5-8x more expensive than PET films | Optimize thickness/grade |
Recyclability | Limited options | Bio-based variants in R&D |
Brittle Handling | Cracks at sharp bends | Hybrid coatings for flexibility |
Adhesion Challenges | Requires surface activation | Plasma treatment pre-application |
10. What is the Difference Between Kapton and Polyimide?
Kapton to polyimide is like Kleenex to tissues – a brand name vs. the material itself. Invented by DuPont in the 1960s, Kapton became synonymous with polyimide films but has unique specs. Generic polyimides might use different diamines (like BPDA instead of PMDA), altering thermal stability. Kapton HN’s trademark orange color comes from specific additives, while off-brand films vary from clear to dark brown. Performance-wise, Kapton maintains tighter thickness tolerances (±2%,) crucial for aerospace, whereas commercial-grade films allow ±10%,. Price reflects this: Kapton costs 20-30%, more but guarantees consistency for mission-critical uses like Mars rovers.
Kapton vs. Polyimide Table
Aspect | Kapton (DuPont) | Generic Polyimide |
Color Consistency | Strict amber | Varies by manufacturer |
Thickness Tolerance | ±2%, | Up to ±10%, |
Price | $$$ | $$ |
Typical Use | Spacecraft, military | Consumer electronics |
11. What is the Difference Between FR4 and Polyimide?
FR4 and polyimide films sit at opposite ends of the PCB material spectrum. FR4 – that green fiberglass in most circuit boards – is the budget-friendly workhorse. But once temperatures soar past 130°C, FR4 delaminates, while polyimide laughs at 260°C soldering. Weight matters too: polyimide boards are 60%, lighter, a lifesaver in drones. However, FR4 dominates consumer gadgets because it’s cheaper (1/5th the cost) and easier to drill. For high-frequency 5G circuits, polyimide’s stable dielectric constant (3.5 vs. FR4’s varying 4.3-4.8) prevents signal loss. Choose FR4 for budget projects; polyimide for extreme environments.
FR4 vs. Polyimide Table
Property | FR4 | Polyimide |
Max Operating Temp | 130°C | 260°C |
Cost per sq. meter | 5−5−20 | 80−80−200 |
Dielectric Constant | 4.3-4.8 | 3.5 (stable) |
Moisture Absorption | 0.1%,-0.3%, | <0.05%, |
12. Difference Between Polyimide Film and Polyester Film
l Polyimide (PI): • Continuous operation up to 260°C (short peaks to 400°C) • No melting point - carbonizes at >500°C • Chinese manufacturers typically guarantee 30,000hrs at 200°C
l Polyester (PET): • Max 150°C continuous (thermal class B) • Melts at 250-260°C - catastrophic failure risk • Common Chinese grades degrade after 5,000hrs at 130°C
l Dielectric Strength: • PI: 200-300 kV/mm (consistent at high temps) • PET: 150-200 kV/mm (drops 40%, above 100°C)
l Surface Resistance: • PI maintains >10¹⁶Ω after humidity exposure • PET can drop to 10¹³Ω in humid conditions
l Tensile Strength: • PI: 150-300 MPa (retains 85%, at 200°C) • PET: 100-200 MPa (loses 50%, strength at 150°C)
l Flex Endurance: • PI withstands 100,000+ dynamic flex cycles • PET cracks after ~20,000 cycles (worse in cold)
l PI Performance: • Resists most solvents except strong alkalies • Stable in transformer oil at 150°C
l PET Limitations: • Attacked by chlorinated solvents • Hydrolyzes in high-humidity, high-temp environments
l Price Differential: • PI films typically 5-8x PET price • But PI lasts 3-5x longer in harsh conditions
l Chinese Market Specifics: • Watch for "PI blend" films (often PET core with PI coating) • True PI manufacturers will show DSC curves proving pure imide structure
Smart Sourcing Tip: Always request:
1. Third-party test reports matching your actual operating conditions
2. Production video showing the actual film being spooled
3. Raw material certificates for monomer sources
At first glance, polyester (PET) and polyimide films seem interchangeable – both flexible, insulating plastics. But test them with a soldering iron, and differences blaze. PET melts at 150°C; polyimide endures 400°C. Need chemical resistance? PET dissolves in acetone; polyimide shrugs it off. Electrically, polyimide’s 10¹⁸ Ω·cm resistivity outshines PET’s 10¹⁶ Ω·cm. However, PET fights back with cost (1/10th the price) and clarity for display screens. While polyimide rules in aerospace motors, PET dominates food packaging and low-cost capacitors.
Comparison Table
Factor | Polyimide | Polyester (PET) |
Heat Resistance | 400°C | 150°C |
Chemical Resistance | Excellent | Poor |
Cost | High | Low |
Transparency | Opaque/Amber | Crystal Clear |
13. What is Polyimide Film Components?
Polyimide’s magic lies in its molecular dance. The stars are aromatic dianhydrides (like PMDA) and diamines (ODA), reacting to form imide rings – nature’s perfect heat-resistant chains. Additives tweak properties: silica nanoparticles boost abrasion resistance, while fluorine groups enhance solubility. The synthesis is a two-step tango: first, creating polyamic acid in chilled conditions, then cyclodehydration at 300°C to form the final film. Some grades include fillers like graphite for conductivity or aluminum oxide for thermal management. It’s a precise recipe – alter one monomer, and you’ve got a completely different material.
Components Breakdown Table
Component | Role | Example Compounds |
Dianhydride | Forms backbone rigidity | PMDA, BTDA |
Diamine | Links chains, adds flexibility | ODA, PDA |
Solvent | Dissolves precursors | NMP, DMAC |
Additives | Enhance specific properties | SiO₂, TiO₂, PTFE |
14. How to Choose Suitable Polyimide Film
l Temperature Class Matters:
• Class H (180°C) vs Class C (220°C+) - verify actual thermal aging tests
l • Request TGA curves (not just datasheet claims)Thickness Realities:
• Standard 25-125μm ranges often have ±5%, tolerance
Critical Questions to Ask Suppliers:
l "Show me your last 3 batches' thickness uniformity maps"
l "What percentage of PMDA is imported vs domestic?"
l "Can we witness production of our specific specification?"
Red Flags in Chinese Factories:
• No separate QC lab with FTIR spectrometer
• Shared production lines with other polymer films
Where to Compromise:
l Color variations (amber vs gold) if purely functional
l Edge trim quality for non-critical applications
Where Never to Compromise:
l Dielectric strength consistency across rolls
l Outgassing properties for vacuum applications
Beyond Standard UL Certifications:
l Peel Strength Test: For adhesive-backed films (many fail after humidity exposure)
l Flex Endurance: 10,000 cycles at 180° bend radius
l Chemical Resistance: 24h immersion in your actual process chemicals
l Moisture Sensitivity: Demand nitrogen-flushed packaging for tropical routes
l Lead Time Realities: Add 2 weeks buffer for customs-cleared shipments
l Payment Terms: 30%, deposit with balance after third-party inspection
Create your own "reference sample kit" with:
1. Your current material
2. Ideal competitor sample
3. Failed import sample
Use these for side-by-side factory comparisons
15. How to Check Polyimide Film Quality
The 5-Step Quality Verification Process Smart Importers Use
1. Physical Inspection (What Most Buyers Miss)
Thickness Variation: Don’t just check edges—measure center points every 50cm on a roll using a micrometer (±3%, tolerance is ideal).
Surface Defects: Use angled LED light to spot:
• Micro-bubbles (indicate poor imidization)
• Streaks (caused by dirty casting equipment)
Roll Tension: Unwind 2 meters—if film "remembers" curl, the annealing process was rushed.
2. Critical Lab Tests (Beyond Supplier Certificates)
Thermal Stability:
• 30min at 300°C then check weight loss (should be <1.5%,)
• Compare CTE (Coefficient of Thermal Expansion) before/after heating
Electrical Properties:
• Test dielectric strength at both 23°C and 150°C (some films degrade at high temp)
• Measure volume resistivity after 24h humidity exposure
3. Factory Process Audit Red Flags
Raw Material Storage: Look for:
• PMDA in original sealed containers (not transferred bags)
• Solvent tanks with nitrogen blankets (prevents oxidation)
Production Logs: Demand to see:
• Last 3 batches’ oven temperature charts
• Scrap rates (>5%, indicates process instability)
4. Packaging & Shipping Checks
Moisture Protection: Reject shipments if:
• Desiccant indicators show >40%, humidity
• Vacuum-sealed bags have visible wrinkles (indicates seal failure)
Roll Identification: Each should have:
• Unique QR code tracing to production data
• Visible lot number matching test reports
5. Real-World Performance Testing
Sample Aging: Bake samples at 200°C for 100h—quality film shows:
• No color change beyond light yellowing
• Less than 8%, elongation decrease
Adhesion Test: Apply your actual conductive inks/adhesives—many failures occur here despite "passing" standard tests.
Pro Tip: Demand "witness testing" where your technician observes the factory’s QC process—this prevents bait-and-switch with pre-selected samples.
16. How is the Polyimide Film Manufactured
The Step-by-Step Reality of Chinese Polyimide Production
1. Raw Material Roulette
l Chinese manufacturers typically use: • Domestic PMDA (less pure than Japanese imports) • Recycled solvent systems (affects film clarity) • Local curing agents (impacts thermal stability)
2. Production Line Secrets
l Casting process variations: • Smaller factories use intermittent coating (causes thickness variations) • Tier 1 suppliers employ continuous casting (better uniformity)
l Critical but often overlooked steps: • Solvent removal at 180-220°C (incomplete drying causes bubbling) • Imidization at 300-350°C (temperature fluctuations create weak spots)
3. Quality Control Shortcuts
l Common problems importers discover: • Thickness measured only at edges (center may vary) • Dielectric tests done on dry samples (ignores humidity effects) • Batch labels that don't trace back to actual production dates
4. What Smart Buyers Verify
l Essential factory checks: • Raw material storage conditions (moisture-controlled?) • Calibration logs for thermal ovens • Waste solvent treatment systems (indicates process control)
Pro Tip: Request video of the actual production line making your specification - many factories show "demonstration lines" that aren't their daily workhorses.
17. Is Polyimide Film Waterproof
Polyimide laughs at water… mostly. Its hydrophobic nature repels liquid water (contact angle: 80°), making it ideal for submarine cables. But humidity? Prolonged 90%, RH exposure causes 0.2%, moisture absorption – negligible for most uses. Want submersion? Pair it with silicone coatings. Watch out: Microcracks from repeated bending create leak paths. For waterproof ratings, check the grade – HN-type films pass IP67 tests, while others may need laminates. In medical sterilization (autoclaves), films retain integrity after 100+ steam cycles.
For international distributors of electrical insulation materials, understanding the waterproof characteristics of polyimide films from Chinese manufacturers is crucial for proper product specification. Here's what sourcing professionals need to know:
Material Baseline Performance
l Standard grade films (25-125μm thickness) absorb 0.4-1.1%, moisture in 24hr immersion (per GB/T 1034 testing)
l Dielectric strength decreases 15-20%, after 500hrs at 85%, RH
l Typical water contact angle: 70-80° (untreated surface)
Enhanced Waterproof Options Available
1. Surface Modified Films
a. Plasma-treated versions (contact angle >100°)
b. Silicone-coated options (IP54 rating achieved)
c. Fluoropolymer laminated types (WVTR <1g/m²/day)
2. Structural Solutions
a. Aluminum foil composites (passes IP67 testing)
b. Multi-layer constructions with PE barriers
c. Edge-sealed rolls for coil applications
Key Sourcing Considerations
l Verify manufacturer testing reports (GB/T 1692 standard)
l Request 1000hr damp heat aging data (85°C/85%, RH)
l Confirm salt spray resistance for marine applications
l Validate coating adhesion (cross-cut test results)
Reliable Chinese Manufacturers Typically Offer
l MIL-I-631D compliant waterproof versions
l Customizable hydrophobicity treatments
l Batch-to-batch consistency guarantees
l Technical support for application engineering
For transformer and motor applications, we recommend specifying films with <0.5%, water absorption and verified 1000hr humidity resistance.
18. What is the Maximum Temperature for Polyimide Film
Polyimide’s thermal limit depends on its “birth certificate” – the monomers used. Standard PMDA-ODA films handle 400°C short-term (10 mins) but cap at 260°C for continuous use. Upgraded BPDA-PDA types survive 500°C bursts in rocket nozzles. Cold? They stay flexible at -269°C (liquid helium temps). Real-world test: Films wrapped around jet engine sensors last 5,000+ hours at 300°C. Warning: Thermal cycling (repeated heating/cooling) degrades films faster than steady heat. For nuclear reactors, radiation-resistant grades maintain properties up to 350°C.
19. Is Polyimide Film Conductive
Polyimide film is emphatically not conductive. It serves as a premier electrical insulator across critical industries.
Polyimide film is widely recognized as an excellent electrical insulator, making it a preferred choice for applications requiring non-conductive materials. The inherent chemical structure of polyimide, characterized by strong covalent bonds and aromatic rings, contributes to its high dielectric strength and low electrical conductivity. These properties ensure that polyimide film effectively prevents the flow of electric current, even under high voltage conditions. This makes it ideal for use in flexible printed circuits, insulating tapes, and other electronic components where electrical isolation is critical.
The non-conductive nature of polyimide film is further enhanced by its ability to withstand extreme temperatures. Unlike many other polymers, polyimide maintains its insulating properties even at temperatures exceeding 400°C. This thermal stability prevents the material from breaking down or becoming conductive under high heat, which is a common issue with lesser insulating materials. Additionally, polyimide film exhibits minimal moisture absorption, ensuring that its electrical insulation performance remains consistent in humid environments. This combination of thermal and moisture resistance makes polyimide film a reliable choice for harsh operating conditions.
Applications of polyimide film in the electronics industry highlight its non-conductive properties. For instance, it is frequently used as a substrate for flexible circuits, where it provides a stable, insulating layer between conductive traces. In transformers and motors, polyimide film acts as an insulating barrier, preventing short circuits and electrical failures.
In conclusion, polyimide film is not conductive in its pure form. Its exceptional electrical insulation properties, combined with thermal and chemical resistance, make it an indispensable material in industries where non-conductivity is essential.
20. What is the Shelf Life of Polyimide Film
Unopened polyimide rolls are the vampires of materials – they don’t age. Stored at 23°C/50%, RH in UV-blocking bags, films last 10+ years. Once exposed, clock starts ticking: Adhesive tapes degrade fastest (2-year shelf life). Humidity sensitivity? Non-issue if kept below 40%, RH. Yellowing occurs after 5+ years in sunlight but doesn’t affect performance.
Standard Storage Conditions
l Temperature: 15-30°C (avoid >40°C)
l Humidity: <60%, RH (critical for moisture-sensitive grades)
l Light protection: UV-resistant packaging required
l Stacking: Maximum 5 cartons high to prevent deformation
Manufacturer VariationsTop-tier Chinese producers now offer:
1. Standard films (2-3 year shelf life)
2. Vacuum-sealed versions (5 year guarantee)
3. Nitrogen-packed premium grades (8 year stability)
Key Degradation IndicatorsImporters should inspect for:
l Yellowing (b* value increase >3 points)
l Brittleness (elongation reduction >15%,)
l Surface crystallization (visible haze)
l Adhesive transfer (liner contamination)
Extended Storage Solutions
1. Climate-controlled warehouses add 1-2 years
2. Desiccant-packed shipments maintain dryness
3. Quarterly rotation system for oldest stock
Certification RequirementsReputable suppliers provide:
l Accelerated aging reports (85°C/85%, RH testing)
l Batch-specific production dates
l Material safety data sheets with storage guidelines
Pro Tip: Always request third-party verified shelf life data rather than manufacturer claims alone.
21. What is 3M Polyimide Film Electrical Tape 92?
If duct tape had a PhD in heat resistance, it’d be 3M’s Tape 92. This amber-colored wizardry starts with a 0.05mm polyimide film base—thinner than human hair—but packs a silicone adhesive that clings through hellfire. Engineers love it for surviving 260°C solder baths without bubbling, while astronauts trust it to insulate wiring in Mars rovers. Unlike cheaper tapes, Tape 92 leaves no sticky residue even after 10,000 thermal cycles. Why? 3M’s proprietary cross-linking chemistry creates a bond that weakens predictably at 300°C, ideal for temporary masking during PCB assembly. The tape’s secret weapon: UL 510 flame certification, making it mandatory in EV battery packs where a single spark could mean disaster. Pro tip: Its 18 lbs/in tensile strength lets you hand-tear clean edges—no scissors needed for motor coil wrapping.
22. How Strong is Polyimide Film?
Try bending a credit card 200,000 times. It’ll snap. Polyimide film? Just getting warmed up. With tensile strength hitting 350 MPa (stronger than cold-rolled steel per gram), this material armors jet engine wiring against vibration that would shred plastics. In peel tests, 25µm films withstand 6.5 kg/cm² before stretching—critical for flexible displays that fold like origami. But raw numbers don’t tell the full story. During the 2021 Perseverance Rover landing, polyimide bushings absorbed 12,000 Gs of shock without cracking. Yet it’s not invincible: Sharp creases create microtears, so manufacturers use laser scoring for controlled folding.
Polyimide film from reputable Chinese manufacturers typically delivers tensile strength ranging from 150-350 MPa, with elongation at break of 40-80%,. These mechanical properties make it one of the strongest polymer films available for electrical insulation applications.
Key Strength Parameters
1. Tensile Performance
a. Standard 25μm film: 170-230 MPa (ASTM D882)
b. Reinforced 125μm grades: 250-350 MPa
c. High-temperature retention: Maintains 85%, strength at 260°C
2. Tear Resistance
a. Elmendorf tear strength: 50-120 N/mm
b. Puncture resistance: 3-8 N/μm thickness
3. Flex Endurance
a. Withstands >100,000 MIT folds (0.5mm radius)
b. Dynamic flex tests show <5%, property loss after 50k cycles
Manufacturing Variations
l Top Chinese producers now offer:Nanoparticle-reinforced films (↑30%, tensile strength)
l Aramid-fiber blended versions (↑200%, tear resistance)
l Surface-treated films for adhesive bonding (↑50%, peel strength)
Quality Verification Tips
1. Importers should request:Batch-specific mechanical test reports (GB/T 1040.3)
2. Third-party validated aging studies
3. Actual production samples for independent testing
Application Considerations
l Motor insulation: Require >200 MPa tensile strength
l Flexible circuits: Prioritize high elongation (>70%,)
l Aerospace: Specify reinforced grades with 300+ MPa
23. Difference Between European and China Polyimide Film
While both regions produce to international standards, smart importers watch for these critical differences:
1. Base Material Variations
l European producers typically use DuPont-style Kapton chemistry
l Chinese manufacturers often modify formulations with: • Cheaper dianhydride precursors (affects thermal stability) • Different solvent recovery systems (impacts surface roughness)
2. Performance Gaps That Matter
l Thermal endurance: • EU films maintain >90%, tensile strength after 1,000h at 260°C • Chinese equivalents average 82-87%, in same conditions
l Thickness tolerance: • EU standard: ±3%, for 25-125μm films • Chinese mills typically achieve ±5%, without premium pricing
3. Certification Realities
l EU suppliers provide: • Full UL File E reports (not just yellow cards) • Lot-traceable RoHS documentation
l Chinese factories often: • Share "company-wide" certs not specific to polyimide • Lack documentation of raw material sourcing
4. Cost-Saving InsightsChinese films can be 30-40%, cheaper but require:
l Upfront dielectric testing (spot check 5%, of rolls)
l Verification of actual glass transition temperature (Tg)
l Moisture barrier packaging during transit
Smart Sourcing Tip: Many Chinese manufacturers now produce "EU-spec" lines for export - look for dedicated production lines rather than mixed batches.
24. Where to Source Polyimide Film for Bulk Wholesale
For importers of electrical insulation materials, finding trustworthy polyimide film suppliers in China requires navigating a complex landscape. Here’s what experienced buyers look for:
1. Key Production Hubs:
i. XuChang/Henan – Highest concentration of certified Polyimide Film manufacturers
b. Shenzhen – Best for quick-turn prototypes (but higher MOQs)
c. Shandong – Lower pricing but verify thickness consistency
2. Supplier Red Flags:
a. "Golden samples" that don’t match production batches
b. Vague answers about cure processes (affects thermal stability)
c. No on-site video verification of cleanroom production
3. Smart Sourcing Tactics:
a. Demand 3rd party test reports for:
• Dielectric strength (>200 V/μm)
b. • Dimensional stability (<0.3%, shrinkage at 300°C)Require container-load inspections before shipment
c. Negotiate payment terms as 30%, deposit, 70%, after batch testing
25. How to Wholesale and Import Polyimide Film from China
Most importers waste months vetting suppliers who can’t actually deliver consistent quality. Here’s how professionals do it:
l Certification Traps: 80%, of "UL-certified" suppliers only have certification for specific thicknesses (usually 25μm). Demand test reports matching your exact specs.
l Production Audits: Require unannounced video walkthroughs showing:
• Cleanroom environments (Class 1000 or better)
• Raw material batch tracking systems
l MOQ Loopholes: Many factories advertise 500kg MOQs but will accept 300kg if you:
• Combine orders with other standard products
l • Agree to quarterly repeat ordersPayment Terms: Never pay 100%, upfront. Standard secure terms:
• 30%, deposit
• 60%, after third-party inspection
l HS Code Games: Some suppliers use 3920.99.00 (general plastics) instead of 3921.90.10 (specific to polyimide) to save export taxes - this risks your customs clearance.
l Moisture Protection: Insist on vacuum-sealed aluminum bags with desiccant - standard plastic wrapping causes hydrolysis during ocean transit.
Pro Tip: Partner with factories supplying EV battery manufacturers - their B-grade stock often exceeds insulation industry specs at 40%, lower cost.
26. How Thick is Polyimide Film?
l Polyimide’s thickness range is a masterclass in extremes. At the slim end: 7.5µm films (think Saran Wrap’s sleek cousin) shield 5G phone antennas without signal loss. Go thick: 250µm sheets line hypersonic missile nose cones. Sweet spots:12µm: Flex circuits in smartwatches
l 50µm: Insulation in EV battery packs
l 125µm: Cryogenic seals for liquid nitrogen
Precision matters. Space-grade films demand ±1µm tolerance—achieved via ultrasonic thickness gauges during casting. But here’s a curveball: Laminating eight 25µm layers outperforms single 200µm sheets in bend tests. For DIYers, US-based DuPont resellers sell 100mm x 100mm samples starting at $25.
27. Is Polyimide Film a Vacuum Coating Substrate?
l In the vacuum coating arena, polyimide is the silent workhorse. Its outgassing rate of 0.01%, TML (total mass loss) beats PET’s 1.2%,—crucial for defect-free gold sputtering in satellite comms. Key applications:ITO coatings: Creates flexible touchscreens without cracking
l Aluminum reflectors: JWST telescope’s sunshield uses 20-layer stacks
l Diamond-like carbon (DLC): Lubricates Mars rover drill bits
But there’s a catch: Films thicker than 75µm tend to curl under high vacuum. Fix? Pre-bake at 150°C for 4 hours to drive off residual solvents. For reference, Tokyo Electron charges $12k to coat 1,000m² of polyimide with 100nm aluminum.
28. What is the Best Adhesive for Polyimide?
l Glueing polyimide is like matchmaking—chemistry is everything. For harsh environments:Silicone adhesives (Momentive TSE392): Withstand -100°C to +300°C, peel strength 4.5 N/cm
l Epoxies (MasterBond EP21TD): 35 MPa shear strength, perfect for copper bonding
l Pressure-sensitive acrylics (Scapa 9040): Removable for prototyping, 2.5 N/cm tack
l Polyimide-based adhesives (Aremco 526N): Laser-weldable for hermetic seals
Avoid cyanoacrylates—they create brittle bonds. Surface prep? A 30-second plasma etch boosts adhesion 300%,. One pro trick: Mix 10%, carbon nanotubes into epoxy for conductive bonds in heater circuits.
29. What is the Alternative to Polyimide Film?
l When polyimide’s overkill or budget-blowing, alternatives creep in:PEI (Ultem): Cheaper, handles 170°C—good for drone motor slots
l PPS Film: Resists acids better, but cracks after 5,000 bends
l TPU: Stretchable for wearable sensors, melts at 80°C
l Aluminized PET: Reflects heat in low-cost insulation
Emerging star: Bio-based polyimide from Showa Denko—50%, plant-derived, degrades in 5 years. Downside: Costs 3x conventional. For high-frequency PCBs, LCP films (like Kuraray’s Vecstar) offer lower dielectric loss but tear like wet paper.
30. What is the Quality Certifications of Polyimide Film
l Certifications are polyimide’s report card. Top marks:UL 94 V-0: Self-extinguishes in ≤10 seconds
l NASA ASTM E595: <1%, volatiles for spacecraft
l ISO 10993-5: Non-toxic for implantable devices
l IPC-4203/11: Flex circuit reliability tests
l EN 45545-2: Rail fire safety (mandatory in EU)
But beware: 2022 saw Wuhan factories counterfeit UL certs—always verify via UL’s online database. Aerospace clients demand NADCAP accreditation for suppliers. Pro tip: Batch-specific DSC reports prove thermal stability—look for Tg ≥ 360°C.
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