| HS Code | 605557 |
| Chemical Composition | Ferric chloride (FeCl3) in aqueous solution |
| Appearance | Clear liquid |
| Color | Dark brown to amber |
| Odor | Pungent hydrochloric acid-like odor |
| Density | 1.30 g/cm3 at 20°C |
| Boiling Point | 106°C |
| Melting Point | -20°C |
| Solubility | Fully miscible with water |
| Ph | 1.5 (typical, acidic) |
| Specific Gravity | 1.30 |
| Vapor Pressure | 1.0 kPa at 20°C |
| Shelf Life | 12 months |
| Storage Temperature | 15-25°C |
| Hazard Classification | Corrosive (H314), skin and eye irritant |
| Etching Rate | Varies with concentration and temperature, typically 25 µm/min for copper |
As an accredited Metal Etchant factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Metal etchant packaged in 1-liter HDPE bottle with secure child-resistant cap and hazard labels. |
| Container Loading (20′ FCL) | Loading 20′ FCL for Metal Etchant: secure corrosive liquid packaging, proper dunnage, ventilation, leak containment, and safe container stowage. |
| Shipping | Metal Etchant is a corrosive hazardous liquid requiring UN-approved packaging, hazard labeling, and complete shipping documentation. Shipments must comply with 49 CFR, IATA, or IMDG regulations. Use ground or cargo-only transport; passenger aircraft is prohibited. Ensure spill containment, proper segregation, and certified personnel for safe handling. |
| Storage | Store Metal Etchant in a cool, dry, well-ventilated area away from direct sunlight and incompatible materials like bases, oxidizers, and reactive metals. Keep in the original, tightly sealed, corrosion-resistant container with clear labeling. Use secondary containment to catch spills, and always handle with appropriate PPE to prevent exposure. |
| Shelf Life | Shelf life is typically 6–12 months unopened; once opened, it degrades faster. Store tightly sealed, cool, and away from light. |
In photochemical machining of AISI 304 and C19400 thin-gauge components, ferric chloride working baths are held at 1.40–1.45 g/mL specific gravity (40–42°Bé) with free hydrochloric acid maintained at 0.5–2.0 vol%; this chloride-rich environment prevents hydrolysis and precipitation of ferric hydroxide during extended production runs. The formulation addition ratio for make-up from bulk 45°Bé concentrate is 1:0.40–1:0.55 with deionized water and acid, and replenishment is metered at 1.0–1.2 L of concentrate per kilogram of dissolved metal, controlled by oxidation-reduction potential at 520–560 mV vs Ag/AgCl. Downstream photochemical machining proceeds by laminating a photoresist film, exposing with collimated ultraviolet light at 365 nm, developing in 1% w/w Na₂CO₃, and spray etching through an oscillating nozzle manifold at 0.8–1.5 bar and 45–50°C. Production process control is maintained under ISO 9001:2015 and ISO 14001:2015; when metallographic verification is required, microetching practice follows ASTM E407-07. Terminal finished products include precision screens, encoder disks, stencil masks, and fuel-cell bipolar plates.
The ammoniacal cupric chloride system used for high-density interconnect printed circuit boards operates at 120–160 g/L cupric ion, 170–200 g/L chloride, and pH 8.0–8.8, with specific gravity 1.18–1.22 and temperature 48–52°C. The formulation addition ratio for replenisher is 0.8–1.2 L per kilogram of copper dissolved, and the ammonia-to-copper molar ratio is held at 2.8–3.2 to prevent sludge while preserving a high lateral-to-vertical etch ratio. The governing standard for finished conductor integrity is IPC-6012E Class 3, with visual acceptance under IPC-A-600K Class 3; RoHS Directive 2011/65/EU applies to the finished board assembly, and process water is managed under ISO 14001:2015. In downstream production, dry-film photoresist is laminated at 1.0–1.2 m/min, exposed by laser direct imaging at 405 nm, developed in 1.0–1.2% w/w Na₂CO₃ at 30–35°C, and etched in a conveyorized spray unit with nozzle pressure 2.5–3.0 bar; the critical process conflict is that raising pH above 8.8 accelerates vertical etching but also increases undercut, reducing the etch factor below 3.0 for 50 µm line-and-space features. Terminal products include HDI boards for automotive engine control units, smartphone main boards, and aerospace avionics.
For aerospace aluminum skins, alkaline sodium hydroxide–based milling solutions are formulated to 150–200 g/L sodium hydroxide with 10–20 g/L sodium sulfide, and the addition ratio for caustic concentrate is 1 L per 20–30 kg of aluminum dissolved; the dissolved aluminum threshold is capped at 60–80 g/L before bath blowdown to avoid viscosity and etch-rate collapse. The etch reaction is exothermic enough that production tanks require immersed titanium or polytetrafluoroethylene heat-exchanger coils to hold 70–90°C within ±2°C, because a temperature excursion above 92°C produces gas bubble blanketing that roughens the milled surface. Process parameters are controlled under AS9100D clause 8.5.1, and corrosion resistance after subsequent conversion coating is validated under ASTM B117-19. Downstream manufacturing begins with a strippable maskant applied to the skin, scribing of window areas, immersion in the alkaline bath for 10–30 min, followed by deoxidizing in nitric acid, rinsing, and thickness inspection by ultrasonic gage; etch depth is timed, and rate is validated on coupon witnesses in each load. Terminal finished product types include fuselage skins, wing skins, and integrally machined panels.
Metallographic preparation of quenched-and-tempered AISI 4140 steel cross-sections relies on nital rather than aqueous acid mixtures because ethanol suppresses hydrolytic attack on non-metallic inclusions. The addition ratio is 2 mL of 65% nitric acid in 98 mL of ethanol for carbon and low-alloy steel, with swab or immersion etching of 5–30 s; for wrought 6061 aluminum, Keller’s reagent is mixed as 190 mL water, 5 mL nitric acid, 3 mL hydrochloric acid, and 2 mL hydrofluoric acid, applied for 20–60 s. The compliance frame is ASTM E3-11 for specimen preparation and ASTM E407-07 for microetching practice. Downstream manufacturing-quality workflows cut sections with water-cooled abrasive wheels, hot-mount in glass-filled phenolic at 150–180°C, grind through P120–P1200 silicon carbide papers, polish with 3 µm and 1 µm diamond suspensions, and etch by immersion or swab before examination at 200×–1000× under reflected light. Terminal product types are polished metallographic specimens, retained as process records, and failure analysis reports used to disposition heat-lot nonconformities.
Because chlorine plasma processes impose thermal and sidewall limitations on back-end CMOS layers, wet etching of titanium and aluminum thin films in MEMS device fabrication is selected when process temperature must remain below 200°C and when tapered sidewall profiles are acceptable. The aluminum etch formulation is prepared at a volume ratio of H₃PO₄:HNO₃:CH₃COOH:H₂O = 16:1:1:2, held at 35–45°C; titanium wet etch uses either dilute hydrofluoric acid at 1–10% v/v or buffered oxide etch at 6:1 NH₄F:HF at 25–30°C, with addition and replenishment of acid components batchwise according to accumulated etch load and inductively coupled plasma mass spectrometry metal monitoring. The process is governed by SEMI S2-0718 for equipment safety and ISO 14644-1:2015 Class 5 cleanroom operation; waste streams are controlled under REACH Regulation 1907/2006/EC. Downstream fabrication uses piranha cleanup at 120°C with H₂SO₄:H₂O₂ = 3:1, hexamethyldisilazane vapor prime, photoresist spin coating at 1.2 µm, exposure, develop, hard bake at 110°C for 60 s, then etch in a recirculating bath with continuous chemical concentration monitoring, followed by deionized wafer rinse and dry. Terminal products include MEMS inertial sensors, microbolometer focal-plane arrays, and RF switches.
In reel-to-reel lead frame manufacturing, copper alloy strip is chemically milled in ferric chloride working baths held at 40–42°Bé with hydrochloric acid concentration 0.5–1.0 vol% and temperature 45–50°C; the addition ratio for make-up from 45°Bé concentrate is 1 part concentrate to 0.4–0.6 parts water and 0.05–0.1 parts hydrochloric acid, with replenisher dosing by redox potential at 500–550 mV vs Ag/AgCl. The compliance specification is JEDEC J-STD-033D for moisture sensitivity classification of finished packages and IATF 16949:2016 clause 8.5.1 for production control; environmental compliance is under RoHS Directive 2011/65/EU. Downstream manufacturing uses a reel-to-reel line: photoresist lamination at 0.8–1.2 m/min, dual-side exposure, carbonate development, spray etching with 1.0–1.5 bar nozzle pressure, resist stripping, silver spot plating at 3–5 µm, and final trim-and-form. Terminal product types include QFN, SOP, and TSSOP leadframes supplied to semiconductor assembly and test houses.
Decorative etching of stainless steel and brass sheet stock uses ferric chloride diluted from 45°Bé bulk to 38–42°Bé working strength, with make-up addition at 1:0.5–1:0.8 concentrate to water and hydrochloric acid held at 0.2–0.5 vol% to maintain clean vertical edges; edge definition after etching is inspected at 20× optical magnification before surface finishing. The process is controlled under ISO 9001:2015, and post-coating corrosion resistance is evaluated under ASTM B117-19 salt spray exposure before release. Downstream production applies photopolymer dry film or UV-cured silkscreen masking, exposes and develops, and spray etches sheet stock at 40–50°C with 0.6–1.0 bar nozzle pressure; etched sheets are rinsed, stripped, brushed or electropolished, and clear coated. Terminal products include elevator cabin panels, signage, interior wall cladding, and nameplates.
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Metal Etchant comprises a family of formulated chemical systems for controlled removal of copper, copper alloys, aluminum, and austenitic stainless steel in printed wiring board fabrication, photochemical machining, and metallographic specimen preparation. The production range includes ME-Cu-C1 cupric chloride-hydrochloric acid etchant, ME-Cu-C2 sulfate-peroxide etchant, ME-SS-F2 chloride-fluoride stainless steel etchant, and ME-Al-M3 alkaline aluminum etchant. Each variant is supplied in 20 L HDPE cubitainers, 200 L HDPE drums, or 1,000 L IBC containers with a certificate of analysis covering specific gravity, free acid or alkalinity, trace chloride, and insoluble matter. Unlike single-component commodity etchants, the formulations include controlled inhibitor packages to stabilize etch rate and reduce undercut variation on production lines where conductor width tolerance is below 15%. The product is not intended for rust removal or thermal oxide stripping; it is specified for defined stock removal and metallographic phase delineation under controlled immersion or spray conditions. Wetted equipment for ME-Cu-C1 and ME-SS-F2 must exclude uncoated carbon steel; CPVC, PVDF, PTFE, and HDPE are acceptable depending on operating temperature.
| Model | Target Alloy | Specific Gravity at 20 °C | Operating Temperature | Nominal Removal Rate | Primary Usage and Distinguishing Characteristic |
|---|---|---|---|---|---|
| ME-Cu-C1 | Electrodeposited and rolled copper | 1.28–1.36 g/cm³ | 48–52 °C | 25–35 µm/min on 35 µm copper at 2.0 kg/cm² spray pressure | Conveyorized spray etching of rigid printed boards and photochemical machining; regenerable cupric chloride chemistry with higher copper loading than ferric chloride |
| ME-Cu-C2 | Fine-line copper and copper alloy foil | 1.10–1.18 g/cm³ | 35–45 °C | 18–25 µm/min at 1.5 kg/cm² spray pressure | HDI and fine-line printed board etching below 75 µm conductor width; sulfate-peroxide chemistry without chlorine regeneration |
| ME-SS-F2 | 300 series austenitic stainless steel | 1.20–1.28 g/cm³ | 20–30 °C | 8–15 µm/min immersion, as-prepared microstructure | Metallographic grain boundary and carbide network delineation; chloride-fluoride formulation requiring HDPE or PTFE wetted equipment |
| ME-Al-M3 | 2xxx, 6xxx, and 7xxx aluminum alloys | 1.10–1.15 g/cm³ | 40–50 °C | 10–18 µm/min immersion on 6061-T6 | Metallographic and chemical milling of wrought aluminum; fluoride-free alkaline system with reduced pitting relative to plain sodium hydroxide |
The nominal values in the table are lot-release and pilot-spray data. Published data for substantially different nozzle geometries and line speeds is limited; qualification trials on the target equipment are therefore required.
In horizontal conveyorized etchers, ME-Cu-C1 is maintained at a free hydrochloric acid concentration of 1.8–2.4 mol/L and a specific gravity of 1.30 ±0.02 g/cm³. Redox potential is controlled between 540 mV and 580 mV versus Ag/AgCl by metered addition of sodium chlorate or 35% hydrogen peroxide. Spray pump discharge pressure is held at 1.8–2.5 kg/cm², and sump temperature is maintained at 50 ±2 °C. At this setpoint, a 35 µm electrodeposited copper foil is cleared in 65–85 seconds. The equilibrium removal rate is not determined solely by chemistry; nozzle type, impingement angle, and conveyor speed create local mass transfer variations. A redox potential below 500 mV reduces cupric ion availability and extends clear time by 30–50%, while a redox potential above 600 mV causes chlorine off-gassing and accelerates passivation loss on titanium heat exchanger surfaces. The upper copper loading limit is 150 g/L; above this value etch factor, defined as depth removed divided by lateral undercut, typically falls below 2.0:1 on 75 µm conductor lines. Production baths are therefore bled and regenerated by electrolytic copper recovery or metathesis to copper sulfate. Copper, free acid, specific gravity, and redox are monitored every 8 hours in accordance with the bath-control procedure referenced in IPC-6012D.
A common production failure mode in cupric chloride lines is suction-side air leakage at the titanium transfer pump, which lowers effective spray pressure and produces localized etch-rate variation even when sump chemistry is in specification. Because the pump curve is comparatively flat across 1.5–2.5 kg/cm², the condition may not be evident from the pressure gauge alone; nozzle pattern inspection and clear-time charting are required. Relative to conventional 42°Bé ferric chloride, ME-Cu-C1 supports a higher dissolved copper concentration before sidewall degradation. Ferric chloride is commonly operated below 80 g/L copper because iron hydroxide precipitation and viscosity increase reduce spray uniformity; regenerable cupric chloride systems are operated at 120–150 g/L copper. Ferric chloride also generates iron hydroxide sludge requiring 10 µm filtration, while ME-Cu-C1 discharges a clear copper-bearing liquor compatible with electrolytic recovery. However, ME-Cu-C1 is not suitable for aluminum or zinc substrates because uncontrolled hydrogen evolution and pitting occur even at ambient temperature.
In photochemical machining of copper alloy foils, ME-Cu-C1 is sprayed at 2.0–2.5 kg/cm² through 0.8–1.2 mm nozzle orifices to remove 50–200 µm stock. Dry-film photoresist is qualified to ASTM D3359-17 adhesion class 4B. For C26000 brass, the etch rate is 12–18% lower than for pure copper because zinc chloride enrichment forms a surface film; a 5 µm filtration loop is recommended to prevent particulate deposition on resist edges. The process window is narrower for copper-beryllium alloys; free hydrochloric acid above 2.4 mol/L can cause uneven sidewall attack and should be reduced by bleed-and-rebuild before processing that alloy.
For fine-line copper processing below 75 µm conductor width, ME-Cu-C2 is specified when chlorine off-gassing and cupric chloride residuals must be avoided. The bath is prepared with ASTM D1193 Type II water and operated at 35–45 °C; temperature is held to ±1 °C because hydrogen peroxide decomposition accelerates significantly with trace iron and thermal excursions. Sulfuric acid concentration is maintained at 1.0–1.5 mol/L, and copper loading is kept below 60 g/L. Above this limit, copper sulfate pentahydrate can crystallize in the lower-temperature zones of the etcher and plug nozzles. The formulation is incompatible with titanium and unpainted stainless steel components because dissolved iron and chromium catalyze peroxide decomposition; wetted parts are CPVC, PVDF, or fluoropolymer. In comparison with ME-Cu-C1, sulfate-peroxide chemistry provides lower undercut on thin copper foil but requires more frequent bath bleed and rebuild and does not support direct electrolytic copper recovery. The bath-life endpoint is defined by a drop in removal rate below 18 µm/min or an increase in top-width loss beyond 12% under the fixed spray recipe described in the product data sheet. The sulfate-peroxide formulation does not contain lead, cadmium, chromium VI, or mercury above the reporting thresholds defined in RoHS 2011/65/EU Annex II, which simplifies waste classification in facilities that track those elements.
When the target structure is austenitic 300 series stainless steel, ME-SS-F2 is applied after mechanical grinding through 600 grit and final polishing to 1 µm diamond. The etchant is used by immersion or swabbing for 10–45 s at 20–25 °C to reveal grain boundaries, twin boundaries, delta ferrite, and sensitized chromium carbide networks. The formulation is diluted relative to standard mixed chloride-fluoride etchants listed in ASTM E407-07 Table 1 to improve reproducibility on 304L and 316L alloys. The fluoride constituent requires HDPE or PTFE containers; borosilicate glass and porcelain are incompatible, and etching is conducted under a fume hood with a face velocity of at least 0.5 m/s. Rinsing follows with ASTM D1193 Type II water and isopropyl alcohol, then drying with filtered compressed air. Overetching beyond 45 s can produce grain boundary widening and false sensitization indications in low-carbon grades. For martensitic 400 series stainless steels, electrolytic oxalic acid etching at 6 V for 15–30 s is preferred because ME-SS-F2 does not provide the same carbide network delineation. Compared with standard Kalling’s No. 2 reagent, the lower copper chloride concentration in ME-SS-F2 reduces copper replating on the specimen surface but extends the time required for heavily cold-worked microstructures. The etchant is not recommended for aluminum or titanium alloys.
Alkaline removal of wrought 2xxx, 6xxx, and 7xxx aluminum alloys is performed with ME-Al-M3 at 40–50 °C; immersion times of 10–25 s are typical for 2024-T3 and 7075-T6 after grinding to 1200 grit. The sodium hydroxide base attacks second-phase intermetallic particles and can generate hydrogen at the specimen surface; therefore, the bath is stored in HDPE and isolated from acidic waste streams because mixing with hydrochloric acid releases heat and may ignite evolved hydrogen in confined drains. The inhibitor package in ME-Al-M3 slows exothermic attack on the aluminum matrix and reduces pitting compared with unmixed 10% sodium hydroxide, but published data for this specific inhibitor system in non-aerospace alloys is limited. The formulation is fluoride-free and does not require hydrofluoric acid waste treatment; however, it does not delineate intermetallic phases as sharply as Keller’s reagent in 2xxx alloys. Endpoint is confirmed by observation of a matte gray surface and cell structure at 50× to 200× optical magnification. The acceptable as-etched microstructure is evaluated under ASTM E407-07 and, where grain size is specified, measured by the planimetric or intercept method of ASTM E112-13. Process temperature above 50 °C shortens immersion time but increases pitting frequency; temperatures below 40 °C require longer immersion and may not develop complete grain boundary contrast.
Compliance and traceability documentation for the product family is maintained under a quality system certified to ISO 9001:2015. The product data sheet references the following standards and regulatory requirements. Compliance with standards does not imply suitability for every use; the user is responsible for validating the etchant under its own process conditions.
| Reference | Designation or Clause | Applicability |
|---|---|---|
| IPC-6012D | Conductor geometry and etch quality sections | ME-Cu-C1 and ME-Cu-C2 on rigid printed boards |
| ASTM E407-07 | Table 1 | ME-SS-F2 and ME-Al-M3 metallographic etchants |
| ASTM E3-11 | Metallographic specimen preparation | ME-SS-F2 and ME-Al-M3 |
| ASTM E112-13 | Grain size measurement | ME-Al-M3 etched aluminum specimens |
| ASTM D1193-06 | Type II reagent water | All dilutions and rinses |
| REACH 1907/2006 | Annexes VII–X | Chemical registration and safety data |
| RoHS 2011/65/EU | Annex II | ME-Cu-C2 heavy-metal reporting thresholds |
Storage conditions are specified in Section 7 of each safety data sheet. ME-Cu-C1 is stored in CPVC or HDPE closed containers at 10–30 °C and must not be mixed with nitric acid, hypochlorite, or cyanide waste streams because chlorine or cyanogen gas can be generated. ME-SS-F2 is segregated from alkaline etchants and ammonia; ammonia in the work area can buffer the acid and reduce etch rate on 316L stainless steel. ME-Al-M3 is not compatible with borosilicate glass, and contact with moisture on raw aluminum fines can liberate hydrogen. The corrosive classification for ME-Cu-C1 and ME-SS-F2 is UN 3264; ME-Al-M3 is classified as UN 1824 when the sodium hydroxide concentration exceeds the corrosive threshold. These assignments may vary by regional regulation and must be confirmed against the current safety data sheet. Empty containers retain hazardous residue and must be drained under local ventilation before disposal.
