| HS Code | 319046 |
| Product Name | Electronic Grade Polyimide Resin (Electronic/EL Grade) |
| Chemical Family | Polyimide |
| Appearance | Clear amber to dark brown viscous liquid |
| Solids Content | 10-30% adjustable |
| Solvent | N-Methyl-2-pyrrolidone (NMP) or equivalent |
| Viscosity | 100-5000 mPa·s at 25°C |
| Specific Gravity | 1.05-1.15 |
| Glass Transition Temperature | 250-310°C |
| Thermal Decomposition Temperature 5 Weight Loss | >500°C |
| Dielectric Constant | 3.0-3.5 at 1 MHz |
| Dissipation Factor | <0.001-0.002 at 1 MHz |
| Dielectric Strength | >150 kV/mm |
| Volume Resistivity | >1×10^16 Ω·cm |
| Surface Resistivity | >1×10^15 Ω/sq |
| Tensile Strength | 100-200 MPa |
| Elongation At Break | 5-20% |
| Moisture Absorption | <1.0% |
| Metal Ion Content Na K Fe Etc | <1 ppm |
| Purity | Electronic grade, low ionic contamination |
| Cure Schedule | Step-cure from 120°C to 350°C |
| Shelf Life | 12 months at 5°C |
As an accredited Electronic Grade Polyimide Resin Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in 1 kg sealed, inert containers to prevent contamination and moisture absorption for electronic-grade purity. |
| Container Loading (20′ FCL) | One 20′ FCL of Electronic/EL Grade Polyimide Resin, packed in sealed drums, securely loaded and ventilated. |
| Shipping | Electronic Grade Polyimide Resin (EL Grade) is shipped in sealed, contamination-free containers to preserve high purity. Temperature-controlled transport prevents degradation, while anti-static and moisture-barrier packaging safeguards electrical properties. Handling requires cleanroom-compatible protocols and careful labeling to avoid contamination, ensuring safe, traceable delivery for sensitive electronics manufacturing applications. |
| Storage | Store Electronic Grade Polyimide Resin (Electronic/EL Grade) in its original, tightly sealed container in a clean, dry, cool environment below 25°C. Protect from moisture, direct sunlight, and dust contamination. Avoid exposure to extreme heat or open flames. Keep away from incompatible materials. Use clean, dedicated equipment. Under proper conditions, shelf life is typically six months from manufacture. |
| Shelf Life | Shelf life is typically 6–12 months when stored sealed, cool, dry, and away from light. |
Electronic/EL Grade Polyimide Resin is specified as a 15–25 wt% polyamic acid solution in N-methyl-2-pyrrolidone for two-layer flexible copper-clad laminate casting, with rotational viscosity at 25°C in the 4,000–20,000 mPa·s range. The cured film is released against IPC-4202/11 for polyimide dielectric film, UL 94 V-0 flammability classification, and ASTM D257-19 volume resistivity above 1×1015 Ω·cm. In reel-to-reel production, the varnish is coated at 18–22 μm wet thickness onto reverse-treated electrolytic copper foil using a comma coater or slot die equipped with closed-loop gravimetric feed; the coated web enters a multi-zone air flotation dryer with nitrogen dew point below −60°C and oxygen below 100 ppm. Pre-dry zones operate at 80–140°C for 8–12 min, and imidization zones hold at 280–350°C for 4–10 min. The critical limit is residual NMP in the film entering final cure: above 500 ppm, blisters and interfacial delamination appear at the copper-polyimide boundary. Production-scale lots are rejected when a 1,000 m roll shows 90° peel strength variation exceeding ±10% from the mean, because downstream flexible printed circuit punching and coverlay lamination cannot compensate for inconsistent adhesion. Cured polyimide thickness after solvent removal is 12–25 μm, with tensile modulus between 2.5 GPa and 4.0 GPa and elongation at break above 30% per ASTM D882-18. The terminal product is two-layer flexible copper-clad laminate converted into flexible printed circuits for smartphone display-to-mainboard interconnects, wearable flex assemblies, and foldable device hinge zones.
For wafer-level passivation and stress-buffer application, the resin is diluted with cyclopentanone or n-butyl acetate to 10–15 wt% solids and filtered through 0.1 μm absolute-rated polytetrafluoroethylene membranes to reduce gel particles below 10 particles/mL at 0.5 μm size by optical particle counting. Compliance obligations include SEMI S2-0718 for coating track equipment safety, SEMI F47-0706 for voltage sag immunity of the nitrogen-purged cure furnace, and ionic impurity acceptance by hot-water extraction followed by ion chromatography per ASTM D4327-17; sodium and chloride in the cured film are held below 0.5 ppm and 1.0 ppm, respectively. The downstream process starts on a 300 mm wafer track with dispense-at-center spin coating at 800–3,500 rpm, solvent-jet edge bead removal, hotplate soft bake at 100–140°C for 90–180 s, and nitrogen cassette furnace cure at 320–350°C for 30–60 min. The temperature ramp from 150°C to 250°C must not exceed 5°C/min; a faster ramp creates a skin that traps solvent and produces surface pinholes. After cure, film thickness is 2–10 μm and total thickness variation across the wafer is held below ±3%, because larger variation shifts bump shear force distribution by more than 10% within a lot. The terminal product is wafer-level chip-scale packaging passivation for power management ICs, MEMS packages, and sensor arrays that are exposed to 260°C peak reflow.
Representative ionic impurity ceilings and solids ranges for downstream sectors are consolidated in the compliance matrix below; values are derived from supplier certificates of analysis and verified by hot-water extraction per ASTM D4327-17 followed by ICP-MS cation analysis.
| Downstream use | Sodium ceiling in cured film (ppm) | Chloride ceiling in cured film (ppm) | Transition metal ceiling (ppm) | Recommended solids range (wt%) | Control method |
|---|---|---|---|---|---|
| Two-layer FCCL | 5.0 | 10.0 | 10.0 | 15–25 | ASTM D4327-17 + ICP-MS |
| Wafer buffer coat | 0.5 | 1.0 | 1.0 | 10–15 | ASTM D4327-17 + ICP-MS |
| Fan-out RDL dielectric | 1.0 | 2.0 | 2.0 | 25–40 | ASTM D4327-17 + ICP-MS |
| OLED display substrate | 1.0 | 3.0 | 2.0 | 15–25 | ASTM D4327-17 + ICP-MS |
| COF carrier tape | 2.0 | 5.0 | 5.0 | 15–20 | ASTM D4327-17 + ICP-MS |
In fan-out wafer-level packaging redistribution-layer dielectric processing, the same polyimide backbone is formulated at 25–40 wt% solids in a 70:30 NMP/γ-butyrolactone blend and spin-coated at 800–1,200 rpm for 30–60 s to deposit a wet film of 20–60 μm. The cured dielectric film of 8–15 μm is qualified against JEDEC JESD22-A104-E thermal cycling from −55°C to 125°C for 700 cycles, JEDEC JESD22-A113 moisture sensitivity preconditioning, and ASTM D882-18 tensile elongation; release criteria require elongation above 20% and modulus between 2.0 GPa and 4.5 GPa. The production sequence comprises spin coating on a reconstituted molded wafer, contact hotplate soft bake at 120–140°C for 180–300 s, UV nanosecond laser via opening at 355 nm with 20–50 μm spot diameter, and nitrogen furnace cure at 320–350°C for 30–60 min. The main process conflict is residual tensile stress from imidization shrinkage: after cure, the dielectric layer can impose 20–40 MPa tensile stress on the reconstituted wafer, and if wafer bow increases by more than 300 μm on a 300 mm panel, subsequent seed-layer sputtering exhibits edge thickness gradients. Published stress data for this exact backbone are limited; therefore the 20–40 MPa band is the on-site qualification range derived from wafer bow measurements on production lots, not a universal resin property. This is controlled by a staged cure ramp not exceeding 2°C/min between 150°C and 220°C and by limiting moisture uptake of the staged film to below 0.3 wt%. Amine-based surface conditioning additives are avoided because they interact with polyamic acid and accelerate solution viscosity drift during coating pot life. The terminal product is the polyimide interlayer dielectric in fan-out wafer-level packages and 2.5D interposer redistribution structures for application processors and baseband packages.
Flexible OLED substrate manufacturing shifts the resin from wafer spin tracks to flat-panel slot-die coating on Gen 6 glass carriers measuring approximately 1,500 mm × 1,850 mm. The formulation addition ratio is 15–25 wt% solids in NMP, with a slot-die gap of 100–300 μm and coating speed from 0.3 m/min to 1.5 m/min. Compliance includes RoHS 2011/65/EU for lead, cadmium, and phthalate restrictions, REACH SVHC screening for display modules assembled in the EU, and ASTM D882-18 tensile property measurement on free-standing polyimide film after peel. The process flow is release-layer deposition on the glass carrier, slot-die coating, vacuum drying at 80–120°C, nitrogen imidization at 350–400°C for 20–60 min, thin-film transistor fabrication, excimer laser lift-off at 308 nm, and film transfer. The cured polyimide substrate thickness is 10–20 μm, and the in-plane CTE is maintained at 8–15 ppm/°C to avoid backplane dimensional drift. The critical production bottleneck occurs at laser lift-off: if the release interlayer absorbs nitrogen-containing species during the polyimide cure step, the required laser fluence shifts from 150–250 mJ/cm² to above 300 mJ/cm², causing carrier microcracking and incomplete separation. Thus the release layer-carrier stack is re-qualified with a 308 nm excimer source whenever the resin lot changes. The terminal product is flexible OLED display substrate for foldable smartphones, curved automotive cockpit displays, and rollable display prototypes.
Chip-on-film carrier tape production consumes Electronic/EL Grade Polyimide Resin at a solids loading of 15–20 wt% in NMP, with rotational viscosity between 5,000 mPa·s and 12,000 mPa·s at 25°C to match comma-coater fluid-flow dynamics. Compliance references IPC-4202/11 for polyimide dielectric film properties, UL 94 V-0 for flammability of the finished tape, and IPC-TM-650 2.4.9 peel-strength testing after chemical exposure; display driver IC packaging also requires the tape to survive 3 reflow cycles at 260°C peak without blistering or delamination. The roll-to-roll line coats the resin onto 12–18 μm low-profile electrolytic copper foil at 3–8 m/min, passes the web through a 5-zone air-flotation dryer with exhaust gas chromatography monitoring of solvent removal, and holds the terminal imidization zone at 320–350°C for 3–5 min. The narrow processing window is molecular-weight drift during storage: when polyamic acid viscosity decreases by more than 10% from moisture ingress, dry-film thickness across a 1,000 m roll can oscillate beyond ±0.5 μm. That thickness variation propagates into inner lead bonding registration error because the downstream sputtered barrier metal and photolithographic lead pattern are indexed to the polyimide surface plane. The terminal product is chip-on-film carrier tape used for display driver IC packages in LCD television panels, OLED smartphone display modules, and automotive display instrument clusters.
For TFT-LCD array planarization layers, the resin is diluted to 8–12 wt% solids in N-methyl-2-pyrrolidone or γ-butyrolactone and applied by slit-spin coating on Gen 8.5 glass substrates. Ionic purity is anchored to hot-water extraction followed by ASTM D4327-17 ion chromatography; sodium in the cured film is held below 1.0 ppm and chloride below 2.0 ppm, because these mobile ions migrate under gate-bias stress and shift thin-film transistor threshold voltage. Additional compliance tests include ASTM D149-20 dielectric strength at a minimum 250 V/μm and ASTM D257-19 volume resistivity above 1×1015 Ω·cm. The production sequence consists of slit-spin coating at 300–800 rpm, prebake at 100–150°C for 2–5 min, and low-temperature imidization at 230–280°C in nitrogen for 30–60 min; the cure ceiling is set by the 300°C thermal budget of the underlying TFT array. The critical control point is residual solvent in the planarization film after cure: if the film retains more than 1.0 wt% NMP as measured by TGA-FTIR, subsequent ITO sputtering generates contact resistance instability at via interfaces. The terminal product is the polyimide planarization layer in active-matrix TFT-LCD backplanes for televisions, monitors, and automotive display panels.
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Electronic Grade Polyimide Resin Electronic/EL Grade is supplied as a high-purity polyamic acid solution dissolved in a polar aprotic solvent system, most commonly N-methyl-2-pyrrolidone or N,N-dimethylacetamide. The product is used in semiconductor packaging for dielectric passivation layers, stress buffer coatings, and redistribution layers on silicon wafers. The Electronic/EL designation identifies a resin lot with reduced alkali-metal, alkaline-earth, and halide concentrations compared with general-purpose polyimide varnishes; supplier certificates of analysis typically specify sodium, potassium, and chloride at 1 ppm or lower per element. Rotational viscosity at 25 °C is generally controlled between 5,000 cP and 20,000 cP, and solids content is maintained between 15 wt% and 18 wt%. The resin is stored at −20 °C to −15 °C to slow imidization and viscosity drift. Because polyamic acid releases water during thermal imidization, films thicker than 10 µm require a controlled cure ramp to avoid interfacial blistering. Packaging is carried out in solvent-resistant containers after filtration through 0.2 µm absolute-rated membrane cartridges.
Representative product forms are Electronic/EL-100 and Electronic/EL-200. The Electronic/EL-100 series is selected when a cured-film coefficient of thermal expansion between 30 ppm/°C and 40 ppm/°C and a tensile modulus near 3.0 GPa are required. The Electronic/EL-200 series is specified for stress buffer layers with elongation above 30 % and CTE values from 45 ppm/°C to 50 ppm/°C. These series differ from standard polyimide varnish not only in ionic content but also in lot-to-lot viscosity tolerance. Standard varnish may show a viscosity range of 3,000 cP to 15,000 cP at 25 °C, whereas Electronic/EL Grade is filtered and diluted to a tighter process window for spin-coating repeatability on automated tracks.
Lot-to-lot variation in electronic-grade polyimide resins is a known processing risk. Differences in polyamic acid molecular weight distribution alter spin-coating thickness at constant spin speed even when viscosity remains within specification. Production facilities therefore qualify each lot by spin-speed curve generation on oxide wafers before release to product wafers. The curve is generated by coating at 1,500 rpm, 2,000 rpm, 3,000 rpm, and 4,000 rpm, measuring cured thickness by spectral reflectance, and fitting thickness against the inverse square root of spin speed. A lot is held if the fitted intercept deviates by more than 5 % from the qualified baseline.
Incoming inspection of Electronic/EL Grade polyimide resin is typically performed before release to wafer fabrication. The test panel includes trace metal content, water content, viscosity, solids content, and particle burden. The values listed below are supplier certificate-of-analysis limits for electronic-grade lots; they are not universal for every manufacturer, and users verify them against their own qualified material specification. Moisture uptake during sampling is a known source of lot rejection, because water reacts with polyamic acid and lowers viscosity.
| Parameter | Typical Electronic/EL Grade limit | Reference method or standard |
|---|---|---|
| Sodium (Na+) | 1 ppm maximum | ICP-MS after microwave digestion, ASTM E1479 |
| Potassium (K+) | 1 ppm maximum | ICP-MS after microwave digestion, ASTM E1479 |
| Chloride (Cl−) | 1 ppm maximum | Combustion ion chromatography, ASTM D7359 |
| Sulfate (SO42−) | 2 ppm maximum | Ion chromatography, ASTM D4327 |
| Iron (Fe) | 0.5 ppm maximum | ICP-MS, ASTM E1479 |
| Copper (Cu) | 0.5 ppm maximum | ICP-MS, ASTM E1479 |
| Water content | 0.5 wt% maximum | Karl Fischer titration, ASTM E203 |
| Viscosity at 25 °C | 5,000 cP to 20,000 cP | Rotational viscometer, ASTM D2196 |
| Solids content | 15 wt% to 18 wt% | Gravimetric, ASTM D2834 |
| Particle count at 0.5 µm | 10 particles/mL maximum | Liquid-borne particle counter, ISO 11500 |
On a production coating track, Electronic/EL Grade is dispensed from a temperature-controlled chemical cabinet through fluoropolymer-lined tubing and a 0.05 µm point-of-use filter. Substrate preparation includes vapor-phase adhesion promotion with hexamethyldisilazane or a silane coupling agent. Spin-coating is performed at 1,500 rpm to 4,000 rpm; the resulting wet film is soft-baked at 90 °C to 110 °C for 90 s to 120 s on a hotplate or in a belt oven. After soft bake, edge-bead removal is carried out with solvent-wetted nozzles, and the film is inspected for comets, striations, and thickness nonuniformity. For a 5 µm cured film, a single-pass spin-coating process at 2,000 rpm for 30 s typically yields a coater uniformity below 3 % across a 300 mm wafer. Final imidization is performed in a nitrogen-purged forced-convection oven or vertical furnace at 350 °C to 400 °C for 30 min to 60 min. The ramp from ambient to cure temperature is controlled at 4 °C/min to 8 °C/min through the solvent-evaporation region between 150 °C and 250 °C. Oxygen concentration is maintained below 10 ppm to prevent oxidative discoloration and surface embrittlement. A slow ramp through the imidization onset range limits water vapor accumulation and prevents blistering. After cure, thickness shrinkage from the soft-baked state is recorded; typical imidization shrinkage for Electronic/EL Grade with 15 wt% to 18 wt% solids is between 10 % and 20 %. Values outside this band generally indicate retained solvent or premature partial imidization in the bottle.
The viscosity of Electronic/EL Grade varies with temperature approximately according to an Arrhenius relation; a 5 °C increase in dispense temperature can reduce viscosity by 10 % to 20 %, shifting spin-coating thickness by several hundred nanometers. On coat tracks without chilled chemical cabinets, intermittent viscosity drift can therefore be mistaken for lot-to-lot variation. Production equipment is set to maintain chemical cabinet temperature at 20 °C ± 0.5 °C. Point-of-use filtration with 0.05 µm rated cartridges may increase pressure drop over the dispense cycle; replacement intervals are set by differential pressure rather than fixed time.
Thermal stability of cured Electronic/EL Grade is characterized by thermogravimetric analysis per ASTM E1131. Typical 5 % weight loss temperature in nitrogen is above 500 °C, and in air the onset of oxidative mass loss is near 400 °C, measured at a ramp rate of 10 °C/min under 20 mL/min purge. Isothermal outgassing at 300 °C for 2 h is recorded by residual gas analysis in qualified processes; the main volatile species below 400 °C are trace solvent and water. When tested according to ASTM E595 after full cure, typical total mass loss is below 1 % and collected volatile condensable material below 0.1 %. These values are cure-temperature dependent; a 350 °C cure may leave a higher outgassing baseline than a 400 °C cure, particularly when solvent retention is present.
Compared with polyimide films based on fluorinated dianhydrides, Electronic/EL Grade typically reports a slightly higher dielectric constant but lower moisture absorption. Fluorinated polyimides may exhibit dielectric constants below 3.0 and lower water uptake, but they are also higher in raw material cost and may require different adhesion promoters. Electronic/EL Grade is formulated for conventional silicon and inorganic dielectric surfaces, not for direct application to copper without an adhesion layer. In contrast, polybenzoxazole resins can be cured at lower temperatures but may show higher moisture uptake after curing and different mechanical stress characteristics.
The primary distinction is ionic purity, but differences in viscosity control, optical clarity, and cure behavior also affect selection. Standard polyimide varnish is used for wire enamel and non-critical conformal coating, where residual metal catalyst content and broader molecular weight distribution are tolerated. Photosensitive polyimide systems incorporate acrylate or naphthoquinone diazide chemistry to permit direct patterning by exposure and aqueous development; Electronic/EL Grade is non-photosensitive and is patterned by photoresist masking or dry etching. The comparison below presents typical cured-film values reported in supplier datasheets. These values are not specifications and should be confirmed for a specific lot and cure profile.
| Property | Electronic/EL Grade | Standard polyimide varnish | Photosensitive polyimide |
|---|---|---|---|
| Sodium content | 1 ppm maximum | 5 ppm to 20 ppm | 1 ppm to 5 ppm |
| Cured-film CTE | 30 ppm/°C to 50 ppm/°C | 40 ppm/°C to 60 ppm/°C | 35 ppm/°C to 60 ppm/°C |
| Dielectric constant at 1 MHz | 3.2 to 3.5 | 3.3 to 3.6 | 3.0 to 3.4 |
| Tensile strength | 150 MPa to 250 MPa | 120 MPa to 200 MPa | 100 MPa to 180 MPa |
| Viscosity at 25 °C | 5,000 cP to 20,000 cP | 3,000 cP to 15,000 cP | 1,000 cP to 10,000 cP |
| Patterning route | Photoresist mask or dry etch | Photoresist mask or dry etch | Direct exposure and development |
| Typical use | Dielectric passivation, stress buffer | Wire enamel, structural film | Passivation with direct patterning |
The residual stress of a cured polyimide film is commonly measured by wafer-curvature methods before seed-metal sputtering. For a 300 mm wafer with a 10 µm cured Electronic/EL-200 film, typical total bow after cure is below 60 µm, although the exact value depends on front-side versus back-side film coverage and prior thermal history. Oxygen leakage in the cure furnace is a critical process variable; even 20 ppm to 50 ppm of oxygen can increase the measured dielectric constant and alter surface wetting for subsequent metal deposition. Production furnaces therefore use load-lock entry, mass-flow-controlled nitrogen, and oxygen analyzers. When quartz furnace tubes are used, batch-to-batch variation in film stress has been traced to door-opening frequency, wafer position, and exhaust flow. Cure recipe validation includes a monitor wafer coated with 10 µm of resin; thickness change between soft bake and final cure is measured by stylus profilometry to verify imidization shrinkage. A shrinkage value below 10 % suggests retained solvent, while a value above 20 % may indicate excessive solids or partial imidization before coating. Both conditions require adjustment of the soft-bake recipe or solvent blend.
Adhesion to silicon nitride, silicon oxide, and copper barrier layers is evaluated by tape peel after cure and after pressure-cooker aging. Failure at the polyimide-substrate interface rather than within the polyimide film indicates a problem with substrate dehydration or the adhesion promoter step. Vapor-phase hexamethyldisilazane at 120 °C for 60 s is a common process window for silicon oxide surfaces; copper surfaces generally require a separate benzotriazole-based pre-treatment or a barrier layer because copper oxide can react with polyamic acid and reduce adhesion. Published data for this specific Electronic/EL grade on copper redistribution layers is limited, and users verify adhesion after thermal cycling rather than relying solely on room-temperature tape peel.
Electronic/EL Grade is not compatible with amine-based hardeners or water-based additives; amines accelerate imidization and increase room-temperature viscosity drift. Containers should be warmed from storage to coating temperature under dry nitrogen before opening, and material should not be held at 25 °C for more than 72 h once opened. At relative humidity above 60 % RH, wafer processing should include a dehydration bake immediately before adhesion promotion, because absorbed moisture can change spin-coating thickness by up to 5 % and reduce film uniformity. Rework of fully cured film is generally not performed with acidic strippers; oxygen plasma or hot N-methyl-2-pyrrolidone is used for partially cured films. The available dielectric characterization for Electronic/EL Grade is typically reported at 1 MHz according to ASTM D150; extrapolation to 28 GHz or higher frequencies requires split-post resonator, microstrip, or broadband dielectric measurements that are not covered by the standard 1 MHz datasheet values.
