| HS Code | 505647 |
| Chemical Name | Isobutanol (2-Methyl-1-propanol) |
| Chemical Formula | C4H10O |
| Cas Number | 78-83-1 |
| Molecular Weight | 74.12 g/mol |
| Grade | Electronic/EL Grade |
| Purity Gc | ≥99.9% |
| Water Content | ≤0.05% |
| Appearance | Clear colorless liquid |
| Boiling Point | 108°C |
| Melting Point | -108°C |
| Flash Point | 27°C (closed cup) |
| Density At 20 C | 0.802 g/cm³ |
| Refractive Index At 20 C | 1.3955 |
| Viscosity At 20 C | 3.9 mPa·s |
| Solubility In Water At 20 C | 8.5 g/100 mL |
| Vapor Pressure At 20 C | 1.2 kPa |
As an accredited Isobutanol Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Isobutanol Electronic/EL Grade is supplied in a 4 L cleanroom-cleaned glass bottle, nitrogen-blanketed, with PTFE closures to preserve purity. |
| Container Loading (20′ FCL) | Isobutanol Electronic/EL Grade is loaded into a 20' FCL using dedicated, purged containers with sealed drums to maintain high purity. |
| Shipping | Isobutanol Electronic/EL Grade ships as a high-purity, flammable liquid. It requires UN-certified containers, proper hazard labeling, and segregation from oxidizers. Transport follows strict regulations to prevent contamination and ensure safety. Temperature-controlled and moisture-free conditions are maintained to preserve its electronic-grade integrity during transit. |
| Storage | Store Isobutanol Electronic/EL Grade in tightly sealed, corrosion-resistant containers to maintain ultra-high purity. Keep in a cool, dry, well-ventilated area away from ignition sources, oxidizers, and direct sunlight. Prevent moisture ingress and static buildup. Use dedicated, clean dispensing equipment to avoid particulate contamination, and label clearly per chemical handling protocols. |
| Shelf Life | Shelf life is typically 12 months from date of manufacture when stored in original sealed containers under recommended conditions. |
On 300 mm coater/developer tracks, isobutanol EL grade is metered into the edge bead removal (EBR) and backside cleaning nozzles before photoresist casting. The branched C4 alcohol shifts the EBR fluid surface tension to 23–25 mN/m at 23 °C, allowing the solvent to wet the bevel exclusion zone without climbing into the active die. Compliance release for this application is anchored to ASTM D1364 water content ≤ 0.10 wt%, ASTM D1209 Pt-Co color ≤ 10, ASTM D1353 non-volatile residue ≤ 5 ppm, and ICP-MS residual sodium, potassium, calcium, magnesium, iron, copper, and zinc each ≤ 1 ppb after evaporation of a 100 mL sample in a pre-cleaned PTFE dish. Isobutanol is blended at 8–25 wt% with propylene glycol methyl ether acetate, ethyl lactate, or 2-heptanone; at loadings above 30 wt% the blend flash point can drop below 25 °C in some solvent combinations, and the evaporation differential across the spinning wafer increases sufficiently to leave a visible drying ring at the edge. The production process occurs on spin-track EBR modules with dispense volumes of 0.8–2.5 mL/s, spin speeds from 800 rpm to 2500 rpm, and exhaust face velocity maintained at 0.3–0.5 m/s. Terminal products include 300 mm logic wafers, DRAM and 3D NAND wafers, and photomask blank substrates where edge clearance and backside metal contamination control are required.
Isobutanol EL grade enters OLED shadow mask cleaning as a high-purity organic solvent formulated to dissolve organic and metal-organic residue accumulated during evaporation source operation and mask alignment. The cleaning bath blend contains isobutanol at 50–70 wt% with a propylene glycol ether and a high-boiling polar aprotic co-solvent; water is limited to ≤ 0.10 wt% by ASTM D1364 because moisture accelerates pitting of invar or SUS-36 alloy mask surfaces. Cleanroom qualification is conducted under ISO 14644-1:2015 Class 5, and ASTM D1209 Pt-Co color ≤ 10 is required to prevent stain residue after drying. Production cleaning proceeds in multi-chamber ultrasonic immersion tools at 35–50 °C with sweeping frequencies of 40 kHz, 80 kHz, and 120 kHz, followed by pressurized N₂ blow-off at 0.4–0.6 MPa and vacuum baking at 80–100 °C for 10–20 min. Terminal products include fine metal masks for RGB evaporation, open metal masks for common layer deposition, and research-level shadow masks used in perovskite and organic photodiode deposition, where organic residue must not redeposit into pixel-defining edges.
| Release property | Test method | Electronic/EL grade control limit |
|---|---|---|
| Purity | GC-FID internal method calibrated to NIST SRM | ≥ 99.5% |
| Water content | ASTM D1364 / ISO 760 | ≤ 0.10 wt% |
| Acidity | ASTM D1613 | ≤ 0.005 meq/g |
| Non-volatile residue | ASTM D1353 | ≤ 5 ppm |
| Color | ASTM D1209 / ASTM D5386 | ≤ 10 Pt-Co |
| Sodium, potassium, calcium, iron, copper | ICP-MS after concentration | ≤ 1 ppb each |
| Chloride | Ion chromatography after extraction | ≤ 50 ppb |
| Particles ≥ 0.2 µm | Liquid optical particle counter | ≤ 50 counts/mL |
| Flash point | ASTM D56 | 28 °C |
During printed circuit board defluxing of high-density interconnect substrates, isobutanol EL grade is formulated into alcohol-ester defluxing fluids to remove rosin, fumaric acid, and tin-lead or lead-free solder flux residues without leaving ionic contamination. The alcohol addition ratio is 15–35 wt%, selected to slow the evaporation of ethanol or isopropanol in the cleaning bath and to increase solvency for oxidized rosin while limiting solder mask interaction to contact times below 3 min. Compliance is based on IPC-J-STD-001H class 3 cleanliness requirements, with ionic residue verified by IPC-TM-650 method 2.3.25 at ≤ 1.56 µg/cm² NaCl equivalence; incoming solvent water is controlled to ≤ 0.10 wt% by ASTM D1364 and non-volatile residue to ≤ 5 ppm by ASTM D1353. The production process includes spray-in-air defluxing at 30–50 °C and 1–3 min contact time, followed by DI water rinsing at 0.5–1.5 L/min per nozzle and forced-air drying at 80–100 °C. Terminal products include engine control units, ABS controllers, and medical telemetry boards where electrochemical migration from ionic flux residues is unacceptable.
Isobutanol EL grade is used in photoresist thinner blends for high-topography spray coating and edge bead control, where its branched aliphatic structure lowers solution viscosity without shifting the solubility window beyond the resist’s compatibility limit. The solvent is added at 10–25 wt% in propylene glycol methyl ether acetate-based thinners; kinematic viscosity is targeted at 3–8 cSt at 25 °C by ASTM D445, and water content in the thinner blend is held to ≤ 0.10 wt% by ASTM D1364. The production process uses precision dispense pumps, sub-micron point-of-use filtration with 0.05 µm PTFE membrane filters, and spray coating in low-humidity tracks held at 45–55% RH and 21–23 °C. Terminal products include power discrete wafers with deep trench features, MEMS inertial sensors with sacrificial oxide topography, and wafer-level optics where viscosity variation across the wafer must remain below ±0.2 cSt.
Semi-aqueous post-CMP cleaning formulations include isobutanol EL grade at 5–15 wt% to lift copper-oxide particulates and organic slurry additives from low-k dielectric surfaces after chemical mechanical planarization. Cleaning tool qualification is performed under ISO 14644-1:2015 Class 3 or Class 4 cleanroom conditions, and the cleaning fluid is filtered through 0.05 µm PFA cartridge filters to maintain particle counts below 50 counts/mL at ≥ 0.2 µm. The downstream production process uses double-sided brush scrubbers with PVA rollers, megasonic nozzles operating at 0.8–1.2 MHz and 20–40 W, and dispense temperatures of 20–40 °C; the isobutanol fraction suppresses water spotting because the alcohol lowers surface tension and increases the vapor pressure of the rinsing fluid in the spin-drying station. Terminal products include copper/low-k interconnect wafers, through-silicon via test vehicles, and bonded wafer pairs prior to thinning. Published data for the exact corrosion inhibition window of isobutanol on cobalt-manganese barrier films in this specific post-CMP configuration is limited; process qualification therefore includes sheet resistance and XPS surface residue mapping before lot release.
Isobutanol EL grade is incorporated into non-halogenated photoresist stripper concentrates at 20–35 wt% to moderate the activity of alkanolamine components and to penetrate highly cross-linked DUV and 248 nm resist films. The solvent’s acidity is controlled by ASTM D1613 at ≤ 0.005 meq/g, and total metals are held below 20 ppb by ICP-MS to avoid plating-out in advanced packaging lines. Downstream stripping is performed in batch immersion tools with cascading baths at 60–80 °C, recirculating filter skids equipped with 0.1 µm PTFE membranes, and bath life monitoring based on gel permeation chromatography molecular weight breakdown and resist particle counts. The process is incompatible with amine-sensitive aluminum pad structures without a specific corrosion inhibitor package, and bath operation above 80 °C raises the vapor pressure of isobutanol to a level that requires sealed tank lids and regenerative thermal oxidizer venting. Terminal products include electroplated copper redistribution layers, pillar bump wafers, and flip-chip molded packages where resist residue must not remain under polyimide passivation after stripping.
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Isobutanol Electronic/EL Grade (CAS 78-83-1; 2-methyl-1-propanol) is a branched C4 alcohol controlled for moisture, trace metals, non-volatile residue, and particle content in semiconductor wet-processing, flat-panel display edge-bead removal, and high-purity precursor dilution. Supplier product codes differ by packaging and purity band; a representative certificate of analysis may carry a designation such as IBA-EL-04, where the suffix denotes a 4N or near-4N assay capability, but the lot-specific certificate remains the binding specification. Distinction from technical-grade isobutanol is based on impurity control rather than base alcohol assay alone. Physical properties include a normal boiling point of 108 °C, closed-cup flash point of 28 °C per ASTM D56-21, density of 0.802 g/cm³ at 20 °C per ASTM D4052-22, and dynamic viscosity near 4.0 mPa·s at 20 °C. The EL designation is not a single regulatory grade; it is a supplier-defined electronic chemical specification aligned to lot-release protocols that typically include GC-FID assay, Karl Fischer moisture, ICP-MS trace metals, ion chromatography for anionic species, and optical particle counting.
Moisture is controlled at lower levels than in general-purpose solvent because water competes with photoresist and precursor chemistry, particularly in metal alkoxide dilution and anhydrous cleaning formulations. EL-grade isobutanol is commonly released with water at ≤500 ppm by weight, measured by ASTM E203-16; high-sensitivity lithography processes may require point-of-use drying to ≤100 ppm. Non-volatile residue is determined gravimetrically after evaporation at 105–110 °C, with representative lot-acceptance limits at ≤5 ppm. Chloride is measured by ion chromatography and is often specified at ≤0.5 ppm because chloride can drive copper electromigration and corrosion in post-etch cleaning. Trace metals are analyzed by ICP-MS after open-vessel or microwave-assisted digestion; sodium, potassium, iron, calcium, and zinc are frequently controlled at or below 10 ppb, and some supply chains maintain sodium and potassium at ≤1 ppb for gate-level processes. Organic impurity monitoring includes 2-butanol, n-propanol, and isobutyraldehyde. Isobutyraldehyde is a reactive aldehyde that can condense with amine-based photoresist components or form colored Schiff-base species; EL-grade material is usually controlled at ≤0.1% by GC-FID. Batch-to-batch variance in high-volume 200 L stainless-steel drums is more commonly observed as moisture rebound after opening than as metal cross-contamination. Production sites with ambient relative humidity above 60% typically require dry nitrogen blanketing to hold sub-500 ppm water during dispense.
In copper/low-k interconnect fabrication, isobutanol EL is evaluated as a cosolvent in semi-aqueous post-etch residue removers where n-methyl-2-pyrrolidone is restricted by process safety or substrate compatibility constraints. Test vehicles include patterned 300 mm wafers with porous organosilicate low-k films at dielectric constant near 2.5; the solvent blend is dispensed through single-wafer spin processors with backside rinse and typical flow rates of 0.5–1.0 L/min. Residue removal is scored by scanning electron microscopy after 30–60 s contact at 45–65 °C. Isobutanol has a higher boiling point and lower vapor pressure than isopropanol, which reduces evaporative cooling and improves contact time on hydrophobic post-etch residues, but also increases the risk of low-k pore absorption and dielectric constant shift after drying. Published data for this specific configuration is limited; suppliers recommend measuring dielectric constant, contact angle, and surface roughness before production qualification. At addition levels above 20 wt% in aqueous tetramethylammonium hydroxide-based cleaners, phase separation and pattern collapse can occur because isobutanol reduces the aqueous phase solubility of the quaternary ammonium hydroxide. Below 10 wt%, the effect on residue selectivity may be too small to distinguish from baseline variation in a production bath.
Bulk delivery of EL-grade isobutanol is typically performed in 200 L electropolished stainless-steel canisters or 4 L fluoropolymer bottles. Cleanroom filling is maintained under ISO 14644-1:2015 ISO Class 5 conditions to limit environmental particle and condensable hydrocarbon ingress. Point-of-use dispensing loops include 0.05 µm PTFE or PFA filters, with particle monitoring by optical particle counters calibrated under ISO 21501-4. Reject thresholds for immersion cleaning baths commonly fall at 100 particles/mL for particles at ≥0.5 µm. Production-scale failure modes include particle shedding from peristaltic pump tubing, moisture ingress through fluoropolymer bottle caps after repeated opening, and static charge accumulation causing particle adhesion to plastic container walls. Pre-wetting filter cartridges with isobutanol before full-flow startup reduces initial particle spiking in some fabs, but the magnitude is process-specific and not a substitute for inline filtration validation. Material compatibility with seals and wetted components is evaluated before conversion from NMP or PGMEA; ethylene-propylene rubber and some perfluoroelastomer grades can swell or extract oligomers into the solvent.
Operationally, the lower evaporation rate of isobutanol EL compared with isopropanol requires longer spin-off and purge times in single-wafer cleaning programs. Solvent film thickness on copper and low-k surfaces after spin drying is affected by both viscosity and surface tension. Isobutanol EL is stored under dry nitrogen in closed containers and protected from direct light; prolonged air exposure increases isobutyraldehyde and isobutyric acid formation, which is monitored as acid value in long-term stability studies. Transfer lines are often configured with low-moisture fluoropolymer tubing and stainless-steel quick-connect fittings to reduce water flux through connectors. For titanium and hafnium alkoxide precursor dilution, moisture is typically held below 100 ppm to prevent premature hydrolysis and M-O-M oligomer formation; in-line FTIR is used to monitor metal-oxygen network growth in precursor delivery lines. Avoid combination with strong oxidizing agents or concentrated nitric acid, because exothermic oxidation can generate carbon oxides and volatile organic vapors.
| Control Parameter | Test Method | Representative EL-Grade Acceptance Limit |
|---|---|---|
| Assay | GC-FID | ≥99.5% area |
| Water | ASTM E203-16 | ≤0.05 wt% (500 ppm) |
| Non-volatile residue | Gravimetric, 110 °C | ≤5 ppm |
| Chloride | Ion chromatography | ≤0.5 ppm |
| Sodium | ICP-MS after digestion | ≤10 ppb; high-purity lots ≤1 ppb |
| Iron | ICP-MS after digestion | ≤20 ppb |
| Particles ≥0.5 µm | ISO 21501-4 optical particle counter | ≤100 particles/mL |
| Isobutyraldehyde | GC-FID | ≤0.1% |
Isobutanol EL differs from semiconductor-grade isopropanol primarily in evaporation rate, water solubility, and branched alkyl character. The normal boiling point of isobutanol is 108 °C, compared with 82.6 °C for isopropanol and 202 °C for NMP, which shifts drying time, film thickness uniformity, and post-clean volatile residue on spin tracks. Closed-cup flash point is 28 °C compared with 12 °C for isopropanol under ASTM D56-21, but the material remains classified as a flammable liquid under GHS; storage must be in grounded, nitrogen-blanketed containment. Water solubility of isobutanol at 20 °C is approximately 8.5 wt%, which limits its use in highly aqueous cleaners unless a tertiary cosolvent is added. Unlike NMP, isobutanol EL is not classified as a reproductive toxicant under Annex VI of CLP; this regulatory distinction is a primary substitution driver in European semiconductor fabs. However, isobutanol is a skin and eye irritant with an ACGIH TLV-TWA of 50 ppm, and airborne vapor monitoring in wet-bench areas is required. The branched C4 structure reduces solvent acidity compared with NMP and shifts Hansen solubility parameters toward nonpolar post-etch residues while retaining a hydrogen-bonding contribution useful for salts and carboxylic acid species.
| Property | Isobutanol EL | Semiconductor IPA | NMP | PGMEA |
|---|---|---|---|---|
| Boiling point at atmospheric pressure | 108 °C | 82.6 °C | 202 °C | 146 °C |
| Closed-cup flash point ASTM D56-21 | 28 °C | 12 °C | 86 °C | 42 °C |
| Density at 20 °C ASTM D4052-22 | 0.802 g/cm³ | 0.785 g/cm³ | 1.028 g/cm³ | 0.966 g/cm³ |
| Viscosity at 25 °C | 4.0 mPa·s | 2.0 mPa·s | 1.7 mPa·s | 1.2 mPa·s |
Differences in solvent drying behavior must be accounted for in edge-bead removal nozzle programs and in batch immersion tools where drag-out carries solvent into subsequent deionized water rinse tanks. Isobutanol EL has lower water miscibility than isopropanol, so rinse water can form temporary solvent-rich boundary layers on wafer surfaces. In ultrasonic cleaning baths, the higher viscosity and lower vapor pressure of isobutanol EL reduce cavitation intensity compared with isopropanol under identical acoustic power; users compensate by raising transducer power or extending process time. For photoresist strip and post-etch residue formulations, the choice between isobutanol EL, NMP, and PGMEA is governed by metal compatibility, low-k damage, evaporation rate, and wastewater discharge limits. Isobutanol EL is not a drop-in replacement for NMP in every formulation; solvent ratio optimization and residue-type screening are required before production use.
