| HS Code | 182400 |
| Chemical Formula | NaOH |
| Cas Number | 1310-73-2 |
| Molecular Weight | 39.997 g/mol |
| Grade | Electronic/EL Grade |
| Purity | ≥99.99% |
| Appearance | White crystalline solid (pellets or flakes) |
| Melting Point | 318 °C |
| Boiling Point | 1388 °C |
| Density | 2.13 g/cm³ at 25 °C |
| Solubility In Water | 1110 g/L at 20 °C |
| Ph Of 1 Solution | 13.0 |
| Vapor Pressure | Negligible at 20 °C |
| Refractive Index | 1.357 (aqueous solution) |
| Hygroscopicity | Highly hygroscopic |
As an accredited Sodium Hydroxide Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Sealed polyethylene liner inside a fiber drum, nitrogen-purged, 25 kg net, ensuring high-purity electronic/EL grade handling. |
| Container Loading (20′ FCL) | 20′ FCL: Electronic-grade sodium hydroxide in secure drums/IBCs, properly braced, labeled, and compliant with dangerous goods regulations. |
| Shipping | Ship Sodium Hydroxide Electronic/EL Grade as UN 1823, Sodium hydroxide, solid, Class 8, Packing Group II. Pack in UN-approved polyethylene-lined bags or drums, clearly labeled corrosive. Segregate from acids, aluminum, and moisture. Use dry, ventilated transport; secure loads; ensure spill kit and PPE availability. |
| Storage | Store in tightly sealed, moisture-proof containers made of compatible materials such as HDPE or lined steel. Keep in a cool, dry, well-ventilated area away from acids, water, and incompatible chemicals. Protect from humidity and physical damage. Use appropriate PPE and segregate to prevent contamination, preserving electronic-grade purity. |
| Shelf Life | Shelf life is typically two years when stored in a tightly sealed original container under cool, dry conditions. |
In monocrystalline Czochralski silicon texturing for photovoltaic cell production, sodium hydroxide Electronic/EL Grade is metered into heated recirculation baths at 1.0–3.0 wt% NaOH with 4–8 vol% isopropyl alcohol and the balance ultrapure water. The chemical source is controlled under SEMI C35, bath water quality is specified to ASTM D5127-13 Type E-1.2, and finished-cell reliability testing is typically performed under IEC 61215-1:2021 after wafer processing. The addition ratio is maintained by conductivity-guided dosing rather than fixed make-up, because evaporation losses of isopropyl alcohol and drag-out of NaOH shift the bath composition independently. In a typical horizontal inline texturing tool, wafers are transported through a heated process tank at 78–85 °C with residence time of 25–35 min, followed by cascading ultrapure water rinses. Etch rates on Si(100) under these conditions are commonly reported in the range of 1.0–2.0 µm/min, producing random pyramidal light-trapping textures with pyramid heights of 2–6 µm. Production-scale equipment failure modes include non-uniform pyramid density when bath temperature variation exceeds ±1.0 °C across the tank, and elevated wafer reflectance when dissolved silicates accumulate above 0.5 g/L as SiO₂. The downstream production process is anisotropic alkaline etching, in which NaOH preferentially attacks Si(100) planes over Si(111) planes, leaving pyramidal structures; hydrogen gas generated at the wafer surface must be removed by continuous filtration and by maintaining adequate isopropyl alcohol concentration for bubble detachment. Raising NaOH above 3.0 wt% increases etch rate but can produce polished facets and excessive undercutting, while reducing isopropyl alcohol below 2 vol% causes coalesced pyramids and unacceptable reflectance. Bath changes are commonly scheduled every 8–12 h because silicate accumulation and atmospheric carbon dioxide absorption reduce etch stability. Terminal finished products are alkali-textured monocrystalline silicon wafers used in PERC and TOPCon cell architectures.
High-layer-count printed circuit boards with epoxy-glass laminates use sodium hydroxide Electronic/EL Grade in both the swell stage and the alkaline permanganate desmear stage. In the swell stage, NaOH is applied at 5–10 g/L at 60–70 °C for 3–5 min to soften the epoxy surface; in the permanganate stage, NaOH is maintained at 30–50 g/L with KMnO₄ at 40–60 g/L, pH 12.8–13.2, and temperature 65–80 °C for 8–15 min. Compliance is anchored to IPC-6012C Class 2 and Class 3 for plated-through hole reliability, and laminate qualification follows IPC-4101D. The downstream production process is a conveyorized or vertical wet-process line in which rigid multilayer panels are immersed sequentially in swell, alkaline permanganate etch, rinse, and neutralizer stages. The etch reaction consumes NaOH and KMnO₄ while generating manganate compounds, so the bath requires automated analysis every 4 h and replenishment of both oxidizer and hydroxide. Production-scale bottlenecks include premature permanganate decomposition when local temperature exceeds 80 °C, and insufficient epoxy removal when NaOH drops below 30 g/L, leaving cup-and-cavity defects at the inner-layer copper interfaces. In horizontal equipment, bath agitation must remain uniform across the working width; pump cavitation or filter blinding from epoxy residues can reduce flow rates below the specified turnover interval and produce uneven desmear on high-aspect-ratio through-holes. Terminal finished products are multilayer and high-density interconnect rigid PCBs with electroless copper coverage on desmeared through-hole sidewalls prior to electrolytic copper thickening.
When sodium hydroxide Electronic/EL Grade is substituted for potassium hydroxide in silicon anisotropic etching and wafer reclaim, the governing constraint is the mobile-ion contamination budget of the target wafer rather than the hydroxide source itself. The addition ratio for bulk silicon removal is 20–30 wt% NaOH in ultrapure water, with isopropyl alcohol added at 10–20 vol%, held at 80–90 °C; under these conditions Si(100) etch rates are typically 1.0–2.5 µm/min, and thermal silicon dioxide etch rates are sufficiently low to provide selectivity ratios exceeding 100:1 in many reported formulations. Material compliance for the EL-grade hydroxide is defined by SEMI C35, while process equipment is specified with polytetrafluoroethylene or polypropylene tanks, quartz immersion heaters, and vented covers for hydrogen evolution. The downstream process is batch immersion etching with recirculation and temperature control of ±0.5 °C across the working volume; wafers are loaded in cassettes, etched to remove films or create micromachined cavities, drained, rinsed in ultrapure water, and often given a dilute hydrochloric acid post-rinse to reduce residual sodium. Production-scale failure modes include non-uniform etch rates when hydrogen bubbles adhere to the wafer surface, and sodium residue on hydrophobic post-etch silicon when rinse water resistivity drops below 18 MΩ·cm. This application is limited to operations where sodium contamination is not a gate-dielectric reliability concern, such as mechanical test-wafer reclaim, MEMS sensor structures, and microfluidic channels. Terminal finished products are reclaimed silicon test wafers and bulk-micromachined silicon components.
Flat panel display substrate cleaning lines use sodium hydroxide Electronic/EL Grade as the alkalinity source in detergent formulations applied before sputter coating of indium tin oxide and before plasma-enhanced chemical vapor deposition. The formulation addition ratio for glass substrate cleaning is 1–5 wt% NaOH in an aqueous detergent mixture, delivered at 40–60 °C with spray pressures of 0.15–0.30 MPa and contact times of 30–120 s. The downstream production process integrates in-line brush cleaning, megasonic energy, final ultrapure water rinses, and air-knife drying; NaOH concentration is monitored by conductivity and replenished by metering pumps tied to bath level and pH. Equipment behavior on production-scale display lines indicates that insufficient rinsing after NaOH exposure can leave sodium residues that shift thin-film transistor threshold voltage; therefore final rinse water quality must comply with ASTM D5127-13 Type E-1.2 and exhibit resistivity above 18.18 MΩ·cm. Material compliance for the hydroxide source follows SEMI C35, while end-panel reliability is verified under IEC 61747 for liquid crystal display devices. Terminal finished products are cleaned TFT-LCD and OLED glass substrates ready for electrode and semiconductor layer deposition.
Regeneration of anion-exchange resins in electronic-grade ultrapure water systems consumes sodium hydroxide Electronic/EL Grade as the principal hydroxyl regenerant. The addition ratio in a typical mixed-bed or separate anion-bed regeneration is 2–5 wt% NaOH, introduced at 35–50 °C and 2–4 bed volumes per hour for 45–60 min, followed by slow displacement and fast rinse with ultrapure water until effluent resistivity exceeds 18 MΩ·cm. The downstream production process includes resin separation, alkaline regeneration of the anion component, countercurrent injection to minimize sodium carryover, and reclassification of mixed beds before return to service. Material compliance for the hydroxide source is SEMI C35; the resulting water must meet ASTM D5127-13 Type E-1.2 and SEMI F63-0917 guidance for ultrapure water used in semiconductor processing, with TOC below <10 ppb and particle counts below <100 counts/mL at ≥0.05 µm. Production-scale bottlenecks include channeling in the resin bed when caustic flow rate exceeds 4 BV/h, leading to incomplete regeneration and sodium leakage above 1 µg/L into the polishing loop. Terminal finished product is electronic-grade ultrapure water used in semiconductor, flat panel, and photovoltaic manufacturing facilities.
Because electroless copper nucleation on palladium-seeded drilled and desmeared through-holes depends on maintaining the bath pH above 12.0, sodium hydroxide Electronic/EL Grade is used as the pH adjuster in electroless copper deposition baths. The addition ratio in a typical formulation is 12–18 g/L NaOH, maintaining pH 12.4–12.8 at 30–36 °C, with EDTA or Quadrol as the complexing agent at 20–40 g/L and formaldehyde at 3–5 g/L. The downstream production process is either vertical dip tank or horizontal conveyorized electroless copper plating, preceded by desmear, microetch, and activation. Continuous air agitation and automatic pH titration with NaOH are required because formaldehyde oxidation consumes hydroxyl ions; copper and formaldehyde are replenished proportionally to maintain deposition rates of 2.5–4.0 µm/h. The bath is filtered through 1–5 µm polypropylene cartridges, and byproduct formate concentrations above 25 g/L typically require partial or full bath replacement to prevent grain-size shifts. Compliance for the plated board is verified by IPC-6012C Class 2 and Class 3, with thermal stress testing per IPC-TM-650 method 2.6.8. Terminal finished products are plated-through-hole multilayer PCBs with uniform electroless copper on the resin and glass wall before electrolytic copper thickening.
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Sodium hydroxide Electronic/EL Grade is an aqueous high-purity sodium hydroxide product controlled for trace-metal, anionic, and particle burdens that are materially tighter than those applied to technical-grade or ACS reagent-grade caustic soda. The material is supplied primarily as a solution with nominal sodium hydroxide concentrations of 45%, 48%, or 50% by weight, though 25% and 32% solutions are available from some producers. The designation “EL” is producer-specific and typically denotes a semiconductor-compatible electronic grade; it is not a harmonized legal mark, and acceptance must be based on the supplier certificate of analysis and specification sheet rather than the label alone. Chemical identity corresponds to CAS 1310-73-2, molecular formula NaOH, and molecular mass 39.997 g/mol. Typical model codes encode concentration and packaging, such as EL-48-1L or 48EL, but exact model nomenclature varies by manufacturer. The dominant delivery forms for electronic use are filtered solutions in fluoropolymer, polyvinylidene fluoride, or high-density polyethylene containers filled under ISO 5 cleanroom conditions. Solid pellets are less frequently specified because on-site dissolution can introduce particle and contamination variability. The product is supplied where sodium hydroxide is chemically required but metallic impurity deposition, particle add-on, or anionic contamination would degrade device yield or surface quality.
The primary distinction is not the sodium hydroxide assay, which can be similar across grades, but the controlled ceiling for transition metals, chloride, chlorate, carbonate, and suspended particles. ACS reagent-grade sodium hydroxide is specified for laboratory use and allows impurity levels in the low mg/kg range; technical diaphragm-cell material is produced for bulk neutralization and is not controlled for particle burden or trace transition metals. Electronic/EL grade material is filtered through 0.2 µm or finer membranes, filled in cleanroom environments, and released against lot-specific trace-metal data generated by inductively coupled plasma mass spectrometry after dilution. The material also differs from technical-grade caustic soda by the reduction of sodium chlorate and sodium chloride to low concentrations because chloride can contribute to metallic corrosion or contamination in wet-bench processing. Producers may include particle count data and pH/conductivity confirmation in the certificate of analysis. The following comparison summarizes typical distinctions across supply forms, though exact limits remain supplier- and model-specific.
| Attribute | Technical diaphragm grade | ACS reagent grade | Electronic/EL Grade |
|---|---|---|---|
| Transition-metal control | Not routinely specified; Fe commonly in low mg/kg range | Fe and heavy metals as Pb specified at low mg/kg levels | Fe, Cu, Ni, Cr, Ca, Mg specified in ppb or sub-ppb tiers |
| Particle burden | Not controlled for microelectronic use | Not controlled | Filtration through 0.2 µm or finer; fill in ISO 5 cleanroom |
| Packaging | Bulk tanks, tank trucks | Drums, cubitainers | Fluoropolymer or HDPE bottles/drums with lot-specific certificates of analysis |
| Target use | Neutralization, pulping, soaps | Laboratory titration, general reagents | Semiconductor etching, cleaning, CMP pH adjustment |
A representative 48% Electronic/EL Grade sodium hydroxide solution is controlled for assay, sodium carbonate, sodium chloride, trace metals, and particle burden within the acceptance windows shown below. These values are representative specification limits, not universal standards, and producer certificates of analysis may apply tighter internal controls for alkali-sensitive or gate-oxide-sensitive processes. Assay is commonly determined by acid-base titration using standardized hydrochloric acid according to ASTM E291. Sodium carbonate is measured by a two-endpoint titration or by total inorganic carbon analysis. Trace-metal determinations are typically performed by ICP-MS after dilution with high-purity water; matrix-matched calibration and internal standards are required because sodium-rich matrices cause signal suppression unless the method is optimized. Particle counts are measured at the point of fill using a laser particle counter calibrated to ISO 21501-1.
| Property | Test method | Typical specification |
|---|---|---|
| Assay as NaOH | ASTM E291 acid-base titration | 48.0–49.0 wt% |
| Sodium carbonate as Na₂CO₃ | ASTM E291 two-endpoint titration | ≤ 0.10 wt% |
| Sodium chloride as NaCl | ion chromatography | ≤ 20 mg/kg |
| Iron as Fe | ICP-MS | ≤ 100 ppb |
| Copper as Cu | ICP-MS | ≤ 20 ppb |
| Nickel as Ni | ICP-MS | ≤ 20 ppb |
| Chromium as Cr | ICP-MS | ≤ 20 ppb |
| Particles ≥ 0.2 µm | ISO 21501-1 laser particle counter | ≤ 100 counts/mL |
Suppliers may also report calcium, magnesium, aluminum, potassium, zinc, cobalt, manganese, and tin data in expanded trace-metal panels. The exact suite and detection limits depend on the analytical instrument and the requested packaging configuration. In semiconductor applications, the relevance of each impurity is not uniform: iron and copper are monitored because they degrade minority-carrier lifetime; aluminum and calcium are monitored because they can precipitate in alkaline cleaning baths; chloride and chlorate are monitored because they influence corrosion at metal interconnect surfaces. Acceptance limits for sodium carbonate are important because carbonate forms by reaction with atmospheric carbon dioxide and can alter etch rate and pH response. High-density polyethylene containers with nitrogen-blanketed headspace and sealed fluoropolymer closures have been observed to reduce carbonate drift during storage compared with open-mouth drums.
At production-scale filling lines, intermittent transition-metal excursions have been traced to stainless-steel impeller wear or seal leakage in transfer pumps. Facilities supplying electronic/EL grade material commonly replace impeller pumps with magnetic-drive or double mechanical seal pumps constructed with fluoropolymer wetted parts. Sample-to-sample variation in iron, chromium, and nickel below 100 ppb is often influenced more by sampling container preparation than by the bulk solution when unpreserved polyethylene bottles are used. Cleanroom filling under ISO 5 reduces aerosol deposition. The product is filtered through 0.2 µm or 0.1 µm absolute-rated filters before fill. Some suppliers use final filtration through polytetrafluoroethylene or polypropylene membranes followed by compressed gas integrity testing. The solution is not sterile, but it is particle-controlled; microbial count is not a standard release criterion.
Sampling and handling for trace-metal measurements require preconditioned fluoropolymer bottles, ultrapure nitric acid stabilization, and blank correction because sodium hydroxide readily leaches metals from glass containers. High-density polyethylene or perfluoroalkoxy bottles are preferred. Analytical laboratories typically perform matrix spike recovery and replicate analysis under ISO 17025 requirements, and lot release is based on the measurement uncertainty of the ICP-MS method. Published particle-size distribution data for this specific grade are limited; most specification sheets report only cumulative counts above 0.2 µm. Users evaluating the material for sub-micron defect-sensitive processes should request full distribution data and compare it with the particle counter calibration and dilution conditions applicable to the bath.
In anisotropic silicon etching, sodium hydroxide Electronic/EL Grade is used as a lower-cost alkaline etchant in bulk micromachining and microelectromechanical systems fabrication. The etch is routinely operated at 70–90 °C with sodium hydroxide concentrations of 10–30 wt%; the exact concentration-temperature window is selected to balance etch rate, (100) surface roughness, and mask selectivity. Crystallographic anisotropy arises because the (111) plane etches substantially slower than (100) or (110) planes, allowing formation of pyramidal or trench structures defined by silicon dioxide or low-stress silicon nitride masks. Published etch-rate data for electronic-grade NaOH-based formulations across all crystal orientations are limited; process characterization wafers are therefore used to map local etch-rate variability on specific production equipment. Transition-metal contamination is particularly important in this application because alkaline etching often occurs before high-temperature oxidation or diffusion steps, and surface-deposited copper, iron, or zinc can diffuse into the silicon lattice. Technical-grade sodium hydroxide in this step can produce low-yield lot signatures that are not visible by optical inspection but appear as threshold-voltage shifts or increased junction leakage. The electronic/EL grade also provides lower particle counts, reducing the density of etch pits caused by localized masking from particle adhesion on the silicon surface.
In photovoltaic cell manufacturing, alkali texturing of p-type monocrystalline silicon wafers produces randomized pyramids that reduce front-surface reflectance. The process typically uses 1.0–3.0 wt% sodium hydroxide at 80–90 °C, with isopropyl alcohol or ethanol added at 2–10 vol% to control surface wetting and regulate pyramid nucleation. Electronic/EL grade material is specified because trace-metal contamination can increase surface recombination velocity and lower minority-carrier lifetime in the finished cell. Sodium carbonate content is also controlled because carbonate can buffer the etching solution and shift the texturing rate or change the preferred pyramid size distribution. Batch-to-batch variation in texturing bath performance has been observed when sodium hydroxide solutions with different carbonate histories are blended; sealed containers and nitrogen overlay reduce this variable. At production scale, the texturing bath is monitored by gravimetric or titrimetric sodium hydroxide determination, and etching time is adjusted based on measured weight loss or reflectance targets. The ruggedness of the process is materially improved by controlling particle burden from the alkali source because particles can act as micromasks and create local over-etch defects on the cell surface.
Electronic/EL Grade sodium hydroxide is used as an alkaline pH adjuster in chemical-mechanical planarization slurry preparation and post-CMP cleaning concentrates. In silica-based slurries, pH is commonly adjusted to 9.5–11.5 depending on the abrasive and passivation chemistry. The addition must be made as a dilute stream with continuous metering and static mixing; direct high-concentration injection can create local pH overshoots that cause colloidal fumed-silica particles to aggregate or gel. In post-CMP cleaning formulations, sodium hydroxide contributes to the alkaline environment that assists removal of residual organic residues and particulate contamination, but it is used at lower concentrations than in etchants. The low iron, copper, and nickel limits of electronic/EL grade material reduce the risk of metal contamination on copper-interconnect or tungsten-contact surfaces during polishing. Aluminum and calcium control is also relevant because precipitation of alkaline-earth silicates or carbonates on pad surfaces can increase microscratch and defectivity. Producers that supply CMP chemical formulators may issue additional analytical data for calcium, magnesium, aluminum, potassium, and sodium carbonate, with limits depending on the intended slurry formulation. Technical-grade caustic soda is generally avoided in this application because transition-metal impurities may deposit on the wafer surface through electrochemical displacement on exposed metal films.
For printed circuit board and advanced packaging wet processing, Electronic/EL Grade sodium hydroxide is applied in alkaline cleaning, photoresist developing in some non-critical applications, and electroless copper bath pH adjustment. In high-density interconnect manufacturing, the product is used where alkaline cleaning must not leave metallic residues that can migrate under solder mask or accelerate dendritic growth under bias and humidity. Sodium hydroxide solutions in this application are typically lower concentration; bath life and contaminant accumulation are monitored by conductivity and by trace-metal analysis. The low chloride content of electronic/EL grade material is relevant because chloride residues on flexible or rigid substrates can support electrochemical migration of copper under high humidity and voltage bias. The same material is sometimes specified in wafer-level packaging where polymer stripping and plasma etch residue removal require an alkaline component that is compatible with downstream copper pillar and redistribution layer metallurgy. Unlike semiconductor front-end use, PCB applications may accept less stringent particle limits, but the trace-metal ceilings and lot-to-lot consistency of electronic/EL grade are still retained.
Despite its alkaline cleaning efficiency, Electronic/EL Grade sodium hydroxide is excluded from most post-gate dielectric cleaning sequences because sodium ions drift readily in silicon dioxide and can produce threshold-voltage shifts or oxide breakdown failures. Even when sodium is present at low ppb levels in the solution, adsorption onto hydroxylated silicon dioxide surfaces can create a mobile-ion contamination source during subsequent thermal processing. This is the reason tetramethylammonium hydroxide or choline-based developers are preferred in front-end post-gate and gate-stack processes. Wafer reclaim facilities that use sodium hydroxide must maintain segregated tools and downstream contamination monitoring to avoid cross-contact with front-end surfaces.
Sodium hydroxide solutions at 48–50 wt% crystallize at temperatures near 10–12 °C; heated storage or lower-concentration grades are therefore used in cold environments. Storage at 20–40 °C in closed, vented containers is typical. The product must not be mixed with concentrated acids without heat removal because neutralization is strongly exothermic and can cause boiling or splattering. Contact with aluminum, zinc, brass, magnesium, and tin should be avoided because alkaline attack releases hydrogen and can damage equipment or create fire risk. Fluoropolymer, polypropylene, and high-density polyethylene are the preferred wetted materials; polycarbonate and polyethylene terephthalate are unsuitable for long-term contact with concentrated sodium hydroxide. Empty containers retain a thin alkaline film and require triple rinsing with high-purity water before disposal or recycling. Dilution with water also releases heat; the correct procedure is to add sodium hydroxide solution to water slowly with mixing rather than adding water to concentrated solution. The material is corrosive to skin and eyes; engineering controls and splash protection meeting ANSI/ISEA Z87.1 for eye protection are applied at production facilities. A supplier certificate of analysis and safety data sheet should be reviewed before introducing the material into a new process because the exact concentration, impurity profile, and packaging configuration influence compatibility at the point of use.
