| HS Code | 380712 |
| Chemical Name | Methyl Ethyl Ketone |
| Synonym | 2-Butanone |
| Cas Number | 78-93-3 |
| Molecular Formula | C4H8O |
| Molecular Weight | 72.11 g/mol |
| Purity | ≥ 99.9% |
| Water Content | ≤ 0.05% |
| Appearance | Colorless clear liquid |
| Color | ≤ 10 APHA |
| Nonvolatile Residue | ≤ 5 ppm |
| Boiling Point | 79.6 °C at 760 mmHg |
| Melting Point | -86 °C |
| Flash Point | -9 °C (closed cup) |
| Density | 0.805 g/cm³ at 20 °C |
| Refractive Index | 1.3788 at 20 °C |
| Evaporation Rate | 3.8 (Butyl Acetate = 1) |
| Solubility | Soluble in water and organic solvents |
As an accredited Methyl Ethyl Ketone Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in a 4-liter high-purity glass bottle with PTFE-lined cap, ensuring contamination-free handling of Methyl Ethyl Ketone Electronic/EL Grade. |
| Container Loading (20′ FCL) | 20′ FCL: securely stow drums of Methyl Ethyl Ketone EL Grade, upright, segregated, ventilated, with proper labeling and blocking. |
| Shipping | Methyl Ethyl Ketone (EL Grade) is a flammable liquid, requiring shipment in UN-approved containers, away from ignition sources. Transport follows strict hazardous material regulations, often via dedicated ground carriers. Ensure proper labeling, grounding, and segregation from oxidizers. Temperature control and leak-proof packaging are essential to maintain ultra-high purity. |
| Storage | Store Methyl Ethyl Ketone (Electronic/EL Grade) in tightly sealed, corrosion-resistant containers under a dry, inert atmosphere. Keep in a cool, well-ventilated, properly grounded area away from heat, sparks, open flames, and strong oxidizers. Prevent contamination and moisture ingress to preserve electronic-grade purity, and follow all flammable liquid storage regulations. |
| Shelf Life | Shelf life: 12 months from manufacture date when stored sealed, under dry, cool conditions, away from light and ignition sources. |
On fully automated surface-mount technology lines, solder paste misprint reclamation and stencil aperture cleaning consume high-purity methyl ethyl ketone electronic/EL grade at rates that scale with stencil aperture density below 0.3 mm pitch and with squeegee blade wear. The solvent is charged into an explosion-proof under-stencil wipe module, where a polyester or nonwoven wipe roll is saturated at 20–25 °C with neat MEK or with a 90:10 v/v MEK/2-propanol blend; the blend is selected when ambient humidity exceeds 60 % RH because the lower evaporation rate of the mixture prolongs contact time on the stencil underside. Solder paste flux vehicles in SAC305 and eutectic SnPb pastes are dissolved by the polar and hydrogen-bonding fractions of MEK; Hansen solubility parameters of δD 16.0 MPa0.5, δP 9.0 MPa0.5, and δH 5.1 MPa0.5 position the solvent within the solubility window for rosin-modified and carboxylic acid activators. Equipment protection interlocks are configured for a closed-cup flash point of −4 °C and vapor concentration below 25 % LEL in the wipe station. Misprinted boards are reclaimed offline in a stainless-steel ultrasonic tank at 40 kHz with a transducer power density of 15–20 W/L; immersion time is 120–180 s for fresh paste and up to 300 s for dried paste containing lead-free alloys. The terminal output is a stencil with 100 % aperture-free-volume recovery and a reconstituted PCB substrate that can be reprinted without delamination or solder mask attack. Compliance is verified by IPC-TM-650 method 2.3.25 for ionic cleanliness and by visual inspection under IPC-A-610; solder mask crosshatch adhesion is checked by ASTM D3359-17 after solvent immersion. Processing limits include incompatibility with natural rubber seals and with polycarbonate housings; all wetted parts are either 316L stainless steel, PTFE, or fluoropolymer-lined.
In high-density PCB assemblies with QFN packages, 0.4 mm pitch ball-grid arrays, and dissipative thermal slugs, flux residue removal is mass-transfer-limited rather than solubility-limited; the primary constraint is the diffusion path of dissolved rosin ester and activator salts through a stagnant solvent layer beneath package standoffs of 0.05–0.25 mm. Electronic/EL grade MEK is applied in a vapor-assisted batch cleaner with alternating immersion and spray cycles. The baseline immersion fluid is neat MEK held at 30–35 °C in a 316L stainless steel process vessel; vapor-phase rinse follows with condensed MEK from a heated sump. The process parameter window is narrow: solution temperature below 20 °C reduces rosin dissolution kinetics to approximately one-third of the reference rate, while temperatures above 40 °C increase solvent loss and require enclosure ventilation above 12 air changes/min. Ultrasonic agitation is typically set to 40 kHz with variable-frequency sweep between 38 kHz and 42 kHz to reduce standing-wave damage on 0201 capacitors. The cleaning solution is monitored by gas chromatography for nonvolatile residue; the replacement trigger is 5 mg/L rosin solids or 50 µS/cm conductivity. After cleaning, boards are dried with filtered dry nitrogen at 80–100 kPa gauge; ionic contamination is verified by IPC-TM-650 2.3.25 with an acceptance threshold of 1.56 µg/cm² NaCl equivalence. Flux residues under QFN thermal pads are inspected by transmission X-ray or by ultrasonic microscopy when solder voiding exceeds 15 % total void area. Terminal products include engine control modules, implantable medical device carriers, and aerospace communication units where chloride-induced dendrite growth is unacceptable.
| Process variable | QFN/BGA deflux | Stencil wipe | Leadframe cleaning |
|---|---|---|---|
| Solvent composition | neat MEK | 90:10 v/v MEK/2-propanol | neat MEK |
| Bath temperature | 30–35 °C | 20–25 °C | 40–50 °C |
| Agitation | 40 kHz sweep ultrasonic | wipe roll contact | 68 kHz ultrasonic |
| Contact time | 180–240 s | continuous per board cycle | 60 s |
| Endpoint control | IPC-TM-650 2.3.25 < 1.56 µg/cm² NaCl eq. | IPC-A-610 visual, aperture free volume 100 % | contact angle < 30°, ASTM D2578 |
| Primary failure mode | residue under thermal pads | paste drying in apertures | pad pitting from ultrasonic cavitation |
Copper, copper alloy, and Alloy 42 leadframes entering thermosonic gold wire bonding lines are cleaned with electronic/EL grade MEK to remove stamping lubricants, anti-tarnish films, and adsorbed moisture prior to plasma treatment. The cleaning sequence is integrated into a reel-to-reel or magazine-based immersion line; the first stage is a 60 s immersion in neat MEK at 40–50 °C with ultrasonic excitation at 68 kHz, chosen to avoid pad surface pitting. The second stage is a vapor rinse using distilled MEK with nonvolatile residue at or below 5 ppm as measured by ASTM D1353. Drying is performed with clean dry air at 60 °C for 20 s. The acceptance criterion is a water contact angle below 30° on bare copper after drying, with ionic residue below 1.56 µg/cm² NaCl equivalence per IPC-TM-650 2.3.25. Wire pull force after thermosonic bonding is verified to MIL-STD-883 Method 2011.7; lot rejection occurs when mean wire pull values fall below the bond-pad-area-adjusted minimum. Terminal products are leadframe-based packages such as QFP, TSSOP, and SOIC configurations. A limitation is that MEK cleaning is not used on silver-spot leadframes with exposed epoxy die attach fillets due to solvent-induced microcrazing; in those lots, alternative hydrocarbon or aqueous cleaning is substituted.
In multilayer ceramic capacitor manufacturing, electronic/EL grade methyl ethyl ketone functions as a carrier solvent in the tape-cast slip for barium titanate dielectric layers. A typical slip formulation contains 60–70 wt% of a MEK/ethanol mixture at 60:40 v/v to 70:30 v/v, 20–30 wt% BaTiO₃ powder with a mean particle diameter of 0.2–0.5 µm, a polyvinyl butyral binder at 4–6 wt% of the ceramic mass, a phthalate-free plasticizer, and a phosphate ester dispersant. The high-purity grade is selected because residual lithium, sodium, and potassium above 0.5 ppm in the solvent alter the dielectric breakdown strength of the fired ceramic. Slip preparation proceeds in a high-shear dissolver at 12–18 m/s tip speed for 2–4 h, followed by vacuum deaeration at 500 Pa absolute for 30 min. The slip is cast onto a silicone-coated polyester carrier film through a doctor blade gap of 25–100 µm; the wet film enters a multi-zone drying tunnel with air temperatures from 50 °C to 80 °C and solvent dew-point control below 5 °C to prevent moisture condensation. Residual solvent in the green tape is measured by thermogravimetric analysis; a residual of 0.8–1.2 wt% before lamination is considered normal, while values above 2 wt% cause layer-to-layer delamination during pressing. The fired terminal product is an X7R or C0G multilayer capacitor with dielectric layer counts from 100 to 600, where solvent metal contamination directly correlates with insulation resistance drift under IEC 60384-1 accelerated humidity. Published data for the specific interaction of MEK electronic grade with nanoscale BaTiO₃ dispersions is limited; batch-level lot acceptance includes ICP-MS metal scans and Karl Fischer water content per ASTM D1364 at ≤0.05 wt%.
| Slip parameter | X7R 0603 | X7R 0402 | C0G 0805 |
|---|---|---|---|
| MEK/ethanol ratio | 60:40 v/v | 65:35 v/v | 70:30 v/v |
| BaTiO₃ content in dried layer | 68–72 wt% | 70–74 wt% | 64–68 wt% |
| Doctor blade gap | 30–50 µm | 25–40 µm | 50–100 µm |
| Drying zone temperature | 60 °C | 55 °C | 70 °C |
| Residual solvent after casting | 0.8–1.2 wt% | 0.7–1.0 wt% | 1.0–1.5 wt% |
In lithium-ion electrode coating lines where dryer length is insufficient for N-methyl-2-pyrrolidone removal at low temperatures, electronic/EL grade MEK is substituted into polyvinylidene fluoride binder systems for cathode and anode slurries. The substitution is conditional on closed-loop solvent recovery, explosion-proof slurry mixing vessels, and controlled moisture content below 0.05 wt% as measured by ASTM D1364. A typical cathode slurry consists of 92–96 wt% lithium nickel manganese cobalt oxide, 2–4 wt% PVDF binder, and 1–3 wt% conductive carbon black dispersed in MEK at a solid content of 45–55 wt%. Mixing is performed in a planetary mixer under vacuum at 500–800 Pa absolute for 90–150 min; the slurry is then coated onto 10–15 µm aluminum foil using a slot-die head with a slot gap of 0.3–0.5 mm at a line speed of 0.5–2 m/min. The faster evaporation rate of MEK relative to NMP permits a first drying zone temperature of 60 °C instead of 120 °C, reducing energy input but increasing the required condensation recovery efficiency to over 95 % under local VOC regulations. Electrode adhesion is tested by a 180° peel fixture per ASTM D903; values below 10 N/m typically indicate binder migration or inadequate surface preparation. The main processing risk is rapid surface skin formation during drying, which can trap residual solvent and reduce electrode density; binder distribution must be verified by cross-sectional scanning electron microscopy. Published data for long-cycle capacity retention of MEK-cast electrodes is limited. The terminal product is a lithium-ion cell electrode calendered to 30–35 % porosity, with lot acceptance governed by IEC 62660-1 mechanical and electrical tests.
In optical coating facilities, electronic/EL grade MEK removes wax, pitch, and hydrocarbon residues from glass, fused silica, and sapphire substrates before thin-film deposition. The cleaning operation uses a two-stage process: first a wipe with a low-lint polyester pad saturated with MEK, then a vapor-rinse in a glass or stainless-steel chamber. The solvent must meet ASTM D1353 non-volatile residue below 5 ppm, and the water content is held below 0.05 wt% by ASTM D1364. Each lot is monitored for particulate counts at 0.5 µm and 1.0 µm via optical particle counter; values above 500 particles/mL at 0.5 µm are rejected. The process temperature is maintained at 18–22 °C to avoid thermal distortion of thin substrates. After cleaning, substrates are blown dry with 0.1 µm-filtered nitrogen and transferred to a vacuum chamber; deposition quality is checked by laser damage threshold testing per ISO 21254-1 or by adhesion tests using MIL-PRF-13830. The terminal products are anti-reflective coated lenses, laser mirrors, and long-pass filters. A limitation is that MEK is not used on polystyrene or acrylic optical components because it can craze the surface.
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Methyl ethyl ketone electronic/EL grade is a high-purity 2-butanone solvent supplied for semiconductor, flat panel display, and precision electronic component manufacturing. The product is identified by CAS RN 78-93-3 and molecular formula C4H8O, with a typical assay minimum of 99.9% for critical wet-bench applications. The electronic/EL designation denotes control of metallic cations, anions, water, particulate matter, and non-volatile residue below the limits normally accepted under ASTM D740-11 for industrial methyl ethyl ketone. The solvent is used in photoresist thinning, edge bead removal, coater cup cleaning, post-strip residue dissolution, and precision cleaning of components where ionic contamination must be minimized. Published data for specific end-user process configurations is limited, but supplier qualification reports commonly align analytical test methods with ASTM D740-11, ASTM D1364-02, ASTM D1613-06, and ASTM D1353-13.
Supplier part-number schemes for the electronic/EL grade are not standardized across manufacturers. Typical packaging includes 4 L amber glass bottles for research and development, 20 L stainless steel pressure cans for pilot use, and 200 L stainless steel drums for production delivery. The grade designation is embedded in certificate-of-analysis metadata rather than in a universal model code; therefore procurement specifications should state the electronic/EL grade limits directly. Some suppliers offer sub-grades with additional low-chloride or low-alpha certifications for advanced packaging and image sensor manufacturing.
Electronic/EL grade MEK differs from industrial MEK primarily in trace-metal burden, particle loading, water content, and residual acid titre. In general industrial MEK, water can be present up to 0.1–0.5% by weight depending on supplier and transport conditions; electronic/EL grade routinely controls water below 0.05%. Total non-volatile residue is reduced from industrial ranges near 10–50 ppm to ≤5 ppm in electronic/EL grade. Acidity as acetic acid is controlled to ≤0.003% versus 0.01–0.02% in standard solvent grades. Trace cations such as Na, K, Ca, Mg, and Fe are typically specified at ≤10 ppb individually and total metals below 50 ppb; industrial grades are generally not certified for metal content at these levels. Additional particulate limits for electronic/EL grade are commonly set at ≤25 particles/mL for particles ≥ 0.5 µm. These specifications are critical because residual metal ions and non-volatile residues can survive thermal processing and modify photoresist contrast or degrade gate oxide integrity.
In gas-chromatographic purity testing for electronic/EL MEK, the difference between 99.5% and 99.9% assay may appear small, but the remaining 0.1% can contain high-boiling condensation products, residual alcohols, and unsaturated ketones that are not acceptable in front-end processes. Industrial grade is often controlled for color, water, acidity, and distillation range only; trace metal and particle specifications are omitted. For electronic/EL grade, the certificate of analysis is expected to report metal concentrations by inductively coupled plasma mass spectrometry, particle counts, and in some cases silica, phosphorus, and chloride content. Without these additional tests, the certificate cannot be used to demonstrate compliance with semiconductor solvent acceptance protocols.
| Parameter | General Industrial MEK | Electronic/EL Grade MEK | Test Method |
|---|---|---|---|
| Assay | ≥99.5% by GC | ≥99.9% by GC-FID | ASTM D740 |
| Water content | ≤0.1–0.5% | ≤0.05% | ASTM D1364 |
| Acidity as acetic acid | ≤0.01–0.02% | ≤0.003% | ASTM D1613 |
| Non-volatile residue | 10–50 ppm | ≤5 ppm | ASTM D1353 |
| Individual trace metals | Not routinely specified | ≤10 ppb | ICP-MS |
| Total trace metals | Not routinely specified | ≤50 ppb | ICP-MS |
| Particles ≥ 0.5 µm | Not routinely specified | ≤25 particles/mL | Laser particle counter |
The shift from general industrial MEK to electronic/EL grade is not limited to tighter water and residue values. Certification requires lot-specific analytical data, clean-container preparation, and traceability of the packaging. General industrial grades may be transported in shared or unlined containers and are not tested for particle count; electronic/EL grade is filled in dedicated, nitrogen-purged packaging and filtered during filling. These process controls are as important as the final certificate values because post-purification contamination during packaging can reintroduce metallic and particulate defects.
Bulk transfer history also differs. Electronic/EL MEK is filled in dedicated lines with nitrogen purge after passivation; general industrial MEK may be shipped in stainless or carbon steel tanks that have previously carried other solvents, with no certificate of cleaning. Such systems can introduce rust, metal flakes, and residual plasticizer additives into the solvent. The electronic/EL grade therefore requires established container management and tamper-evident seals.
In high-volume semiconductor fabs, methyl ethyl ketone electronic/EL grade is supplied in dedicated stainless steel or fluoropolymer returnable containers, transferred under nitrogen pressure, and dispensed through 0.05–0.2 µm point-of-use membrane filtration to preserve particle specifications. Wet-bench and coater-cup equipment typically use 316L electropolished stainless steel or PFA/PTFE wetted surfaces because MEK can swell certain elastomeric seals and leach extractables from incompatible polymers. Field experience on coater cup cleaning stations indicates that solvent delivery lines without nitrogen blanketing can exceed the ≤0.05% water specification within 8–12 h in high-humidity fab bays; in-line moisture analyzers are therefore installed for critical photoresist thinning operations. The solvent is applied at 20–25°C or pre-warmed to 40–50°C in closed recirculation baths for post-strip residue removal. Tool maker service guides typically specify flush flow rates in the range of 10–30 mL/min for coater cup cleaning; actual parameters are recipe-controlled and vary with wafer size, resist type, and chamber airflow.
During edge bead removal, electronic/EL MEK is dispensed from the spin-coater solvent nozzle to dissolve resist at the wafer perimeter before coating uniformity defects form. The solvent evaporates quickly enough to prevent migration into the active die area but not so fast that it dries inside the nozzle; this balance is affected by exhaust airflow and spin speed. In wafer cleaning after dry-strip or ash processes, the product may be used in ultrasonic or megasonic baths at 20–40°C to remove residual organic films. However, ultrasonic cavitation in open baths can increase evaporation and moisture uptake; therefore closed-loop systems with chiller condensers and dry nitrogen blankets are preferred for particle-sensitive layers.
Material qualification for electronic/EL MEK is typically tied to SEMI C8 guidance for organic solvents used in semiconductor manufacturing. Each incoming lot is tested for water by ASTM D1364-02 Karl Fischer coulometric titration; acidity is determined by ASTM D1613-06 titration; non-volatile residue is measured by gravimetric evaporation and reported in ppm. Density is controlled by ASTM D4052-18a and used as a blend consistency check. Inductively coupled plasma mass spectrometry detection limits for trace metals are set below 1 ppb for Na, K, Ca, Mg, Fe, Cu, and Zn, with control limits reported at ≤10 ppb for individual elements and ≤50 ppb total. Particle counting uses light-scattering instrumentation capable of resolving particles from 0.2 µm upward; the certificate of analysis normally records particles ≥ 0.5 µm and ≥ 1.0 µm per milliliter. The user acceptance window is often narrower than the supplier upper specification limit because in-line filtration can be compromised by high particle load and repeated solvent recycling. Published data for specific lithographic material interactions is limited; therefore qualification should include wafer-level defect inspection and film-strip testing rather than relying solely on bulk solvent certificates.
Anion contamination is controlled because chloride and sulfate can initiate corrosion on exposed copper or aluminum interconnects. Ion chromatography is performed with detection limits around 10–50 ppb for chloride, nitrate, phosphate, and sulfate. Representative specification bands reported in supplier literature vary; common control limits are set at ≤0.5 ppm for chloride and ≤1 ppm for sulfate, but these values should be confirmed against the actual supplier certificate and the process corrosion sensitivity.
Water is not merely a solvent-specification issue; in chemically amplified resist systems, excess water can alter acid generation and dissolution rate. A change of 0.02–0.05% in moisture content can shift developer clearing times in sensitive resist formulations. Therefore the product is often stored under nitrogen or fitted with molecular sieve dryers in recirculating lines.
MEK electronic/EL grade is selected over electronic-grade acetone when a ketone medium with higher boiling point and lower headspace volatility is required. MEK has a boiling point of 79.6°C, density near 0.805 g/cm³ at 20°C, and a closed-cup flash point of -9°C; acetone boils at 56.2°C and exhibits higher vapor pressure at ambient conditions, which can reduce dwell time in ultrasonic cleaning vessels. Compared with NMP, MEK does not introduce nitrogen-containing residues but has a lower flash point and higher evaporation rate; it is therefore confined to short-residence cleaning and spin-processing steps rather than long soak baths. Relative to PGMEA, MEK provides faster evaporation and can be used where film residues must be removed without extended bake-out. The selection is validated through residue removal efficiency tests, metal contamination tracing, and surface roughness measurements; no single solvent substitution can be made without requalifying the cleaning and coating sequence. Published data for this specific configuration is limited when the photoresist chemistry contains high-molecular-weight acrylate monomers.
The boiling point difference between MEK and acetone also impacts vacuum-drying cycles. In heated wafer cleaning modules, a 79.6°C solvent may leave less residual liquid after pressure reduction than acetone, but it may also increase the exposure time needed for removal from high-aspect-ratio features. For substrates with narrow trenches or through-silicon vias, wetting and contact angle behavior are process-specific; published data for this configuration is limited. Substitution evaluations typically include contact angle measurement on patterned wafers, post-clean elemental analysis by TXRF or VPD-ICP-MS, and device electrical test lot splits.
For flat panel display and hard disk drive component cleaning, the product is filtered at point of use and often blended with co-solvents to modulate evaporation. Anhydrous electronic/EL MEK is used in polarizer cleaning lines where sodium and potassium residues must remain below detectable levels after drying. In these operations, solvent purity is checked at the receiving stage by ICP-MS and moisture analysis because replenished tanks in high-humidity cleanrooms can accumulate water from ambient exchange. Returnable containers are pressure-blanketed with 99.999% nitrogen; wetted seals are specified as FFKM or ultra-high molecular weight polyethylene rather than Buna/NBR, which can swell and release extractables. A documented incompatibility is with strong oxidizing agents and concentrated mineral acids; contact with hydrogen peroxide, nitric acid, or chlorine-bleach solutions can generate heat and hazardous decomposition products. Therefore storage and dispensing lines are segregated from oxidizers and waste drains are maintained separately.
Printed circuit board fabricators use electronic/EL MEK in selective cleaning of bare boards and stencils where halide contamination can lead to electromigration. The solvent is sometimes applied through ultrasonic immersion lines at 25–35°C for 2–5 min; bath life is determined by acid number increase above 0.01% and particle rise above 25 particles/mL. In these lower-grade electronic applications, the EL product may be blended with isopropanol or ethanol to reduce evaporation, but such blends must be requalified for residue after drying.
Electronic/EL grade MEK is flammable and should be stored in grounded, closed containers below 25°C and away from ignition sources. The lower explosion limit in air is 1.8 vol% and the upper explosion limit is 10.0 vol%; area electrical classification and local exhaust are determined by these values. Exposure limits include an ACGIH TLV of 200 ppm and an OSHA PEL of 200 ppm. Under repeated solvent recycling, distillation can concentrate non-volatile residues and degrade the product below electronic/EL specification; revalidation is required after 2–3 recycle passes in closed solvent recovery loops. Material should not be blended with amine-based strippers for long-term storage because aldol condensation can proceed under basic or oxidative conditions; published kinetic data for this electronic-grade formulation is limited. Incompatibilities include strong oxidizers, strong Lewis acids, and some chlorinated cleaning agents. When the product is exposed to water above 0.05%, moisture can contribute to photoresist scum and surface hazing in sensitive metal lift-off processes.
Explosion limits are lower 1.8 vol% and upper 10.0 vol%; flash point is -9°C; autoignition temperature is 404°C. Equipment grounding and nitrogen blanketing are mandatory when material is heated above ambient. Vapor concentrations in coater cup areas are controlled below 25% of the lower explosion limit; local exhaust flow is validated by anemometer and gas detection calibration.
