| HS Code | 666210 |
| Chemical Composition | Mixture of organic solvents (e.g., NMP, DMSO, glycol ethers) and additives |
| Purity | Electronics/EL grade, typically ≥99.9% |
| Appearance | Clear, colorless to pale yellow liquid |
| Water Content | ≤0.1% (by Karl Fischer) |
| Boiling Point | 150-210°C |
| Flash Point | >60°C (closed cup) |
| Density At 20c | 0.95-1.10 g/cm³ |
| Metal Impurities | Each metal (Na, K, Ca, Fe, Cu, Ni, Zn) ≤1 ppm |
| Solubility | Miscible with common organic solvents; limited water solubility |
| Stripping Capacity | Effectively removes photoresists, polymers, and organic residues |
| Storage Condition | Store sealed at 15-25°C away from light and moisture |
| Shelf Life | 12 months under recommended storage conditions |
As an accredited Solvent-Based Stripper Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Solvent-Based Stripper Electronic/EL Grade is packaged in sealed 1-gallon and 5-gallon HDPE containers, ensuring safe handling and purity. |
| Container Loading (20′ FCL) | 20′ FCL loaded with UN-approved drums of solvent-based electronic-grade stripper, secured, labeled, and containerized for safe transport. |
| Shipping | Solvent-Based Stripper Electronic/EL Grade ships as a hazardous liquid requiring UN-approved containers, proper labeling, and ground/air transport compliance. Ensure segregation from oxidizers and acids, use secondary containment, and provide safety data sheets. Temperature-controlled, leak-proof packaging prevents vapor release and contamination during transit. |
| Storage | Store Solvent-Based Stripper Electronic/EL Grade in a tightly sealed, original container in a cool, dry, well-ventilated area away from direct sunlight, heat, sparks, and open flames. Keep away from oxidizers, acids, and moisture. Use grounded containers and bonding during transfer. Ensure secondary containment and follow manufacturer's temperature guidelines to maintain purity. |
| Shelf Life | Store tightly sealed, away from heat/ignition. Shelf life is typically one year from manufacture date when unopened. |
In aluminum-metallized semiconductor front-end processing, post-etch bulk photoresist stripping on 200 mm power-management and analog/mixed-signal wafers typically employs immersion baths formulated with 70–85 wt% N-methyl-2-pyrrolidone or dimethyl sulfoxide, 10–20 wt% monoethanolamine or diglycolamine, 1–5 wt% catechol or tert-butylcatechol as an aluminum corrosion inhibitor, and 0.1–1 wt% nonionic wetting agent. The bath is maintained at 65–75°C for 5–15 min to remove 1.5–3.0 μm i-line positive photoresist that has been crust-hardened by plasma etch. After immersion, the wafers are transferred to an intermediate isopropanol or acetone bath to displace the high-boiling stripper film before a final rinse with electronic-grade water conforming to ASTM D5127-13. Copper etch on exposed redistribution lines is specified below 2 nm/min at 70°C when coupon-tested per ASTM G31-72(2017); aluminum etch remains below 0.5 nm/min for the catechol-inhibited blend. Direct water rinsing without the intermediate solvent is excluded because localized pH depression at the stripper/water interface initiates aluminum hydroxide pitting. The target end product is the aluminum metal-stack wafer with intact bond pad and interconnect line profiles prior to barrier metal deposition or passivation. Bath life is monitored by viscometry; replacement is scheduled when kinematic viscosity rises above 8 mm²/s at 25°C or when particle counts exceed 100 particles/mL at 0.2 μm.
For thick positive diazonaphthoquinone resists used in copper pillar bumping and redistribution layers, solvent-based strippers are formulated near anhydrous because dissolved water accelerates cuprous oxide formation and increases copper etch rate in immersion and puddle tools. A representative blend contains 50–70 wt% dimethyl sulfoxide, 20–35 wt% propylene glycol monomethyl ether acetate or diethylene glycol dimethyl ether, 5–10 wt% tetrahydrofurfuryl alcohol to swell crosslinked crust, and 0.5–2 wt% benzotriazole as a cuprous surface passivator. Water is controlled below 0.5–1.0 wt% by Karl Fischer titration; batches above 1.0 wt% are rejected because copper etch coupons tested per ASTM G31-72(2017) show a transition from oxide-free surface retention to galvanic plating-line failure at 85°C. Spray or puddle processing at 80–90°C removes 20–40 μm resist features within 3–8 min; temperature must be held within ±2°C because benzotriazole inhibitor desorbs from copper above 95°C. The post-strip rinse sequence begins with anhydrous isopropanol, then electronic-grade water per ASTM D5127-13, followed by low-organic ash or spin-rinse drying. End products are copper pillar bumps of 20–50 μm diameter and 40–70 μm pitch used in fan-out wafer-level packaging and 2.5D interposers. Cationic impurities are controlled at <10 ppb for sodium, potassium, and iron because copper/interlayer dielectric interfaces are sensitive to mobile-ion drift. Published data for this specific anhydrous stripper configuration is limited; therefore pre-qualification on patterned copper wafers is mandatory before release to bumping lots.
Hydroxylamine-containing solvent blends are applied after reactive ion etching to remove sidewall polymer residue from via and trench structures in low-k dielectric integration. The active bath is formulated with 5–15 wt% hydroxylamine, 10–25 wt% alkanolamine, 3–8 wt% catechol-based inhibitor, and the balance N-methyl-2-pyrrolidone or dimethyl sulfoxide. Single-wafer spray tools operate at 65–75°C for 60–120 s, followed by a solvent-vapor-drain step to limit pH shift. The process window is narrow because hydroxylamine decomposition accelerates above 90°C; exothermic runaway is reported in supplier safety literature for closed-loop lines with insufficient cooling. Flash point of the blended product is tested per ASTM D93-20, and process interlocks are set below 85°C vessel skin temperature. Residue removal is evaluated by scanning electron microscopy: bottom polymer in 0.18–0.35 μm vias is cleared without observable damage to titanium nitride caps. Etch rate on exposed copper is maintained below 1.5 nm/min; on aluminum alloy, below 0.5 nm/min. The end products are high-aspect-ratio interconnect vias and trenches before metallization. Rinsing uses polar solvents rather than direct water where porous low-k films exhibit capillary stress; subsequent volatile organic removal is performed under 250°C thermal budget with less than 2% residual modifier. Fresh bath particle counts are filtered to <50 particles/mL at 0.2 μm using 0.1 μm absolute cartridge filtration. Batch-to-batch variance in catechol redox state is monitored by absorbance at 430 nm; an absorbance increase above 0.15 AU leads to bath change.
Flat-panel display array processing imposes particle and metal contamination limits tighter than most wafer-level post-strip operations because residue on TFT backplanes creates visible pixel defects. Electronic-grade solvent strippers for LCD and OLED arrays are typically blends of 60–80 wt% dimethyl sulfoxide, 10–20 wt% diethylene glycol dimethyl ether, 5–10 wt% alkanolamine, and <1 wt% high-purity inhibitor. Spray processing on Gen 8.5 and Gen 10.5 glass is conducted at 40–50°C with 60–180 s contact time to remove 1.0–2.0 μm photoresist after wet etch or dry etch. The stripper is recirculated through 0.05 μm filtration; metal impurities are maintained below 5 ppb for sodium, potassium, magnesium, and zinc on certificate of analysis. Rinse water must meet ASTM D5127-13 Type E-1 criteria, and wet-bench environments are controlled per ISO 14644-1:2015 Class 5 or better. Water uptake in the stripper is limited to 1.0 wt% because polymer solvency falls sharply; lot data from display fabs show edge bead residue recurrence when bath water exceeds 1.2 wt%. The end products are amorphous silicon or low-temperature polysilicon TFT arrays used in OLED backplanes and LCD active-matrix panels. Plasma damage on indium tin oxide is avoided by using the solvent bath before ITO sputtering; the stripper is not applied post-ITO unless corrosion inhibitor compatibility has been proven on ITO coupons.
Physical property benchmarks for the primary solvents referenced in the stripping bath designs are summarized below.
| Solvent | Kinematic viscosity at 25°C (mPa·s, ASTM D445-21) | Closed-cup flash point (°C, ASTM D93-20) |
|---|---|---|
| N-methyl-2-pyrrolidone | 1.65 | 86 |
| Dimethyl sulfoxide | 1.99 | 87 |
| Propylene glycol monomethyl ether acetate | 1.2 | 45 |
| γ-Butyrolactone | 1.7 | 98 |
In III-V compound semiconductor processing, liftoff sequences require solvent-based strippers that swell the sacrificial positive photoresist without attacking aluminum or gold bond pads. A typical anhydrous liftoff medium contains 70–85 wt% γ-butyrolactone or N-methyl-2-pyrrolidone, 10–20 wt% diglycolamine, 1–3 wt% gallic acid ester inhibitor, and 0.5–1 wt% nonionic surfactant. The bath is heated to 60–70°C and ultrasonically agitated at 40 kHz for 5–10 min to clear resist patterns with undercut morphology. After lift-off, substrates are transferred promptly to a solvent intermediate; direct water contact on exposed aluminum bond pads causes pitting attack at residual amine concentrations above 0.1 wt%. Aluminum etch is maintained below 0.3 nm/min for 60°C exposure, and gold pad reflectivity is unchanged after 30 min immersion. End products include GaAs HEMT gate structures, GaN RF devices, and InP photonic components with metal lift-off dimensions below 0.5 μm. The low-moisture formulation prevents aluminum hydroxide formation during ultrasonic cavitation; Karl Fischer water is controlled below 0.5 wt%. Viscosity is measured per ASTM D445-21 to ensure consistent ultrasonic transmission; bath replacement is indicated when viscosity exceeds 6 mm²/s or when filtered particle counts rise above 50 particles/mL at 0.2 μm. Published data for GaAs-specific lift-off stripper baths is limited to supplier application bulletins and compound semiconductor process reports, so coupon-level corrosion pre-qualification is required for each new bond pad metallurgy.
On copper leadframes and pre-plated QFN surfaces, transfer molding and die attach operations generate uncured or partially cured epoxy squeeze-out that must be removed without attacking silver, nickel, or palladium finishes. Electronic-grade solvent strippers used for selective bleed removal are formulated with 50–70 wt% ethyl lactate or γ-butyrolactone, 10–20 wt% propylene glycol methyl ether, 5–10 wt% tetrahydrofurfuryl alcohol, and 1–2 wt% benzotriazole as a silver/nickel passivator. The bath is sprayed at 45–55°C for 3–8 min; this temperature is below the softening point of the partially crosslinked epoxy, so bulk molded packages remain dimensionally stable. Silver roughening on plated leadframes is below 1 nm Ra after 10 min exposure, while nickel and palladium finishes show no visible tarnish under 50× inspection. Cured epoxy molding compound is not removed by this solvent chemistry; only uncured or partially cured bleed and transfer residue are solvated. The leadframes are rinsed with isopropanol and then dried with filtered nitrogen to avoid water spotting on silver finishes. The end products are clean leadframes and package arrays ready for wire bonding or die attach, with no amine residue that would inhibit subsequent adhesion. Viscosity is controlled between 2 and 5 mm²/s at 25°C for uniform spray coverage; flash point is reported per ASTM D93-20 and requires equipment classification for Class I Division 1 areas. Operators monitor bath conductivity and replace the stripper when conductivity exceeds 50 μS/cm, indicating metal salt extraction from plated surfaces.
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Solvent-Based Stripper Electronic/EL Grade is a low-metal, low-particle solvent formulation used for post-etch and post-implant photoresist removal in wafer-level packaging, copper pillar bumping, redistribution layer formation, and through-silicon via processing. The product is supplied as a single-component blend of N-methyl-2-pyrrolidone, dimethyl sulfoxide, and a tertiary amine alkalinity source, with a benzotriazole-based copper corrosion inhibitor and a chelating component for metal-fluoride residues. The Electronic/EL Grade designation separates the material from industrial solvent strippers by lot-release controls for trace cations, chloride, water, and non-volatile residue. Representative lot data include sodium ≤ 20 ppb, potassium ≤ 10 ppb, iron ≤ 10 ppb, calcium ≤ 10 ppb, and zinc ≤ 5 ppb by ICP-MS following SEMI C1 protocols. Chloride is controlled to ≤ 0.5 ppm by ion chromatography per ASTM D512-23. Kinematic viscosity at 25 °C is 2.9–3.6 mm²/s by ASTM D445-21, and density at 20 °C is 1.03–1.07 g/cm³ by ASTM D4052-22. Water content is ≤ 0.10 wt% by ASTM E203-21. Closed-cup flash point is 74 °C by ASTM D93-20, defining heated tooling and ventilation limits.
| Property | Target range | Test method |
|---|---|---|
| Kinematic viscosity at 25 °C | 2.9–3.6 mm²/s | ASTM D445-21 |
| Density at 20 °C | 1.03–1.07 g/cm³ | ASTM D4052-22 |
| Water content | ≤ 0.10 wt% | ASTM E203-21 |
| Closed-cup flash point | 74 °C | ASTM D93-20 |
| Chloride | ≤ 0.5 ppm | ASTM D512-23 |
| Sodium | ≤ 20 ppb | SEMI C1 ICP-MS |
| Iron | ≤ 10 ppb | SEMI C1 ICP-MS |
| Non-volatile residue | ≤ 5 ppm | ASTM D1353-13 |
For single-wafer spray tools, the product is normally dispensed at 65–75 °C through a 316L electropolished stainless steel or PFA delivery line with a 0.1 µm PTFE point-of-use filter. Process qualification on a 300 mm spray processor typically evaluates 60–120 s exposure at 0.5–1.5 L/min flow. Batch immersion strippers operate at 60–70 °C for 10–20 min with recirculation through a 0.2 µm filter. Rinsing with deionized water at 25–50 °C is followed by isopropyl alcohol drying; insufficient rinse can leave non-volatile residue above the 5 ppm lot limit by ASTM D1353-13.
In recirculated immersion tanks, solvent blending affects the lower explosive limit and evaporation rate. The amine concentration is titrated by non-aqueous acid-base methods and is reported as amine value; fresh product typically shows 10–14 mg KOH/g by ASTM D2073-22. Replacement is triggered when the amine value falls below 8 mg KOH/g because removal rate of deep-UV-cured resist becomes non-linear. Water absorption from ambient air shifts the solvent polarity and reduces solvation of novolac-based photoresist films; bath life is therefore managed to a water limit of 0.8 wt%, measured at line by Karl Fischer titration. Open tanks require local exhaust ventilation with face velocity not less than 0.5 m/s and nitrogen blanketing when bulk temperature exceeds 60 °C. Wetted components of aluminum or unlined mild steel are excluded because the amine component can etch aluminum and generate hydrogen.
In spray-tool configurations, the dispense nozzle material is typically 316L stainless steel or perfluoroalkoxy polymer, and the fluid path is kept below 30 psig to limit aerosol formation. Point-of-use filtration at 0.1 µm removes particle adders from valve wear, but filter change-out must occur when differential pressure exceeds 15 psi because larger pressure drops can cause filter bypass or solvent flash in the housing. Equipment interlocks are set to stop dispense if exhaust airflow drops below the lower limit specified in SEMI S2.
Crosslinked photoresist after high-dose ion implantation or deep-UV curing presents a skin layer that slows solvent penetration. The Electronic/EL Grade relies on a polar aprotic solvent mixture with Hansen solubility parameters optimized for cresol novolac and polyhydroxystyrene resists; the tertiary amine cleaves ester and imide crosslinks by aminolysis. Removal rate is temperature-dependent, increasing by approximately 2.0–2.5× between 50 °C and 70 °C in supplier wafer-level test data. At the same time, the benzotriazole inhibitor suppresses copper attack; supplier immersion data show a copper etch rate ≤ 2 Å/min at 70 °C for exposures up to 30 min by gravimetric mass loss adapted from ASTM G31-72(2021). On copper pillars with tin-capped surfaces, process validation should include cross-section inspection after repeated stripping cycles because solder-capping alloys can be selectively affected at immersion times exceeding 15 min.
Compared with aqueous alkaline strippers based on tetramethylammonium hydroxide, the solvent-based Electronic/EL Grade has lower surface tension and improved wetting into high-aspect-ratio vias and under bump metallization edges. Aqueous TMAH formulations commonly require higher temperatures and can show anisotropic removal on re-entrant profiles; however, they do not introduce the volatile organic compound handling burden associated with NMP/DMSO mixtures. Compared with fluorinated solvent strippers, the Electronic/EL Grade typically provides faster solvation of positive novolak photoresist but requires a deionized water rinse to remove ionic residues. Fluorinated solvents may penetrate sub-100 nm features more readily and present lower flammability, but their solvency for heavily crosslinked resist can be insufficient without co-solvents.
| Stripper class | Single-wafer removal time for 1.5 µm implanted resist | Copper etch rate | Primary limitation |
|---|---|---|---|
| Solvent-Based Stripper Electronic/EL Grade | 60–120 s at 1.0 L/min | ≤ 2 Å/min by ASTM G31 supplier lot data | VOC and flash point controls |
| Aqueous TMAH stripper | 120–240 s at 85 °C | ≤ 1 Å/min with inhibitor package | Higher surface tension; profile anisotropy |
| Fluorinated solvent stripper | 180–300 s at 60 °C | ≤ 0.5 Å/min | Limited solvency for high-dose implant crust |
Dry-etch residues from reactive-ion etching often contain metal fluorides that resist alkaline hydrolysis. The chelating component in the Electronic/EL Grade coordinates aluminum and titanium species and assists in dispersing residue from via sidewalls. For tungsten-rich residues, an intermediate warm deionized water rinse at 40–50 °C before the final solvent rinse is recommended because partial hydrolysis of tungsten fluoride improves removal efficiency. For aluminum fluoride residues, the stripper should not be combined with oxidizing pre-treatments or extended bath aging beyond the water limit, because fluoride release can complex with the amine and reduce the free alkalinity available for resist stripping. On wafers with exposed titanium-tungsten adhesion layers, electrochemical galvanic effects require verification; the supplier recommends split-lot testing on patterned wafers because published data for this specific configuration is limited.
In via chains with tungsten plugs and titanium nitride barriers, incomplete residue removal can appear as contact resistance variation across the wafer. A two-step process consisting of immersion stripping at 70 °C for 12 min, followed by a deionized water intermediate rinse at 45 °C and a final isopropyl alcohol rinse, has been used to reduce via resistance spread in supplier application tests. Because the solvent swells the remaining photoresist before complete dissolution, the intermediate rinse should not be omitted when the aspect ratio exceeds 5:1.
The closed-cup flash point of 74 °C by ASTM D93-20 requires that bulk fluid temperature be maintained at least 10–15 °C below the flash point in open equipment unless nitrogen inerting is applied. Heated recirculation loops should be designed with low-velocity returns below the liquid surface to reduce vapor generation; pump seals should be magnetically coupled or double mechanical seals with barrier fluid. Cartridge filters should be replaced only when the loop temperature is below 40 °C. Ventilation interlocks and solvent vapor sensors are applied in closed cabinets; maintenance procedures follow SEMI S2 equipment safety guidelines and NFPA 30 flammable liquid storage classifications. Because the product contains N-methyl-2-pyrrolidone, waste streams are segregated and evaluated under REACH and local industrial wastewater discharge permits; NMP is not incinerated in uncontrolled municipal waste streams.
The flash point imposes a narrower processing window than aqueous strippers, but the solvent blend is formulated so that the stripping rate at 65 °C remains adequate for most copper RDL processes. In closed-loop systems with nitrogen blanketing, temperatures up to 75 °C can be used for short intervals if the oxygen concentration in the headspace is maintained below 8% and solvent vapor monitoring is active. Open-bath operation above 65 °C without inerting is outside the recommended boundary.
Water ingress changes the activity of the tertiary amine and can increase metal-fluoride deposition rather than residue removal. At water concentrations above 0.8 wt%, the single-component stripper becomes less homogeneous, and phase separation may occur in cold zones of the recirculation line. This condition is observed in production immersion tanks that are not sealed between shifts or that receive wafers without sufficient post-rinse drying. When phase separation occurs, the pH measured after dilution in deionized water can shift outside the normal 11.2–11.8 range, and the removal rate of ion-implanted resist can drop by more than 50%. The amine value alone is not a sufficient indicator because water dilution can mask the titration result; both water content and amine value are recorded at line for bath release.
Particle control is monitored at point-of-use with laser particle counters calibrated with NIST-traceable polystyrene latex spheres. A single-wafer spray process using a 0.1 µm PTFE filter can maintain particle adders below 20 particles per wafer at ≥ 0.2 µm in a Class 1000 cleanroom, but only when the dispense line is flushed after each lot. Trace metal deposition on bare silicon after double-pass application is controlled to ≤ 1×10¹⁰ atoms/cm² for sodium and aluminum, measured by vapor phase decomposition inductively coupled plasma mass spectrometry; this value is used as a lot-release criterion for gate oxide integrity-sensitive flows.
Against semiconductor-grade NMP-only strippers, the addition of dimethyl sulfoxide in the Electronic/EL Grade increases the polarity range and accelerates swelling of polyhydroxystyrene-based resists. Against methylene chloride/phenol strippers, the Electronic/EL Grade eliminates chlorinated solvent exposure and phenolic disposal classification but has a lower evaporation rate in vapor degreaser configurations. Against d-limonene-based terpene strippers, the Electronic/EL Grade has narrower lot-to-lot variation for trace metals but higher toxicity labeling for the amine fraction. These differences are evaluated by material compatibility testing according to ASTM D543-20 for polymer seals and tubing before tool installation.
The stripper should not be used on substrates containing unpassivated aluminum in continuous immersion because hydrogen generation can occur at the metal surface; for such structures, an aqueous development cleaner is substituted. Compatibility with porous low-k dielectrics must be verified by k-value shift measurement after 30 min immersion at 70 °C and subsequent cure, because solvent absorption into pores can affect dielectric constant. Published data for advanced porous low-k films below 2.2 dielectric constant is limited; lot qualification on patterned wafers is required.
