| HS Code | 437560 |
| Chemical Composition | Copper chloride, ammonium chloride, ammonium hydroxide, and water |
| Appearance | Clear liquid |
| Color | Deep blue to dark blue |
| Odor | Ammoniacal |
| Ph | Approximately 8.5 to 9.5 at 25°C |
| Specific Gravity | Approximately 1.20 to 1.25 at 25°C |
| Boiling Point | Approximately 100°C |
| Freezing Point | Approximately -20°C |
| Vapor Pressure | Approximately 17 to 20 mmHg at 20°C |
| Solubility | Fully miscible in water |
| Copper Content | Typically 14% to 18% by weight |
| Ammonium Chloride Content | Typically 5% to 10% by weight |
| Ammonia Content | Typically 3% to 6% by weight |
| Heavy Metal Impurities | Electronic/EL grade with individual heavy metals typically below 1 ppm |
| Shelf Life | 6 months to 1 year in sealed original container |
As an accredited Alkaline Etchant Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in 5-gallon pails or 55-gallon drums, with sealed, corrosion-resistant containers ensuring purity for electronic-grade use. |
| Container Loading (20′ FCL) | 20′ FCL container loaded with Electronic/EL Grade Alkaline Etchant, secure drum packaging, hazard-compliant, safe segregation, ready for transport. |
| Shipping | Alkaline Etchant Electronic/EL Grade ships as a corrosive basic liquid under UN 3266, Hazard Class 8. It must be packaged in UN-approved HDPE drums or carboys, properly labeled, with acid segregation. Ensure intact seals, upright orientation, and compatible containment to prevent leaks during transport. |
| Storage | Store Alkaline Etchant Electronic/EL Grade in tightly sealed, original containers in a cool, dry, well-ventilated area away from direct sunlight, heat, acids, and incompatible materials. Maintain temperatures between 15–30°C, avoid metal contamination, and keep containers upright to prevent leaks. Ensure secondary containment and accessible emergency equipment are available. |
| Shelf Life | Store tightly sealed and cool; shelf life is typically 6–12 months from manufacture for electronic/EL grade alkaline etchant. |
Inside a conveyorized spray etcher configured for mSAP HDI production, a 2–5 µm electroless copper seed layer is removed from spaces after pattern plating. The electronic/EL grade alkaline etchant contains ammonium hydroxide, ammonium chloride, and cupric ion, and is maintained at 48–50 °C, pH 8.8–9.2, free ammonia 4.5–5.5 mol/L, and copper loading 5–30 g/L. Oscillating fan-spray nozzles operate at 1.8–2.2 bar, and the conveyor speed is held between 2.5 and 3.5 m/min. The etch depth is limited to 2–5 µm for seed removal, while pattern-plated traces of 20–30 µm remain protected by tin or dry film. The dominant process conflict is lateral undercut: an over-etch of 15 s can narrow isolated lines by 2–4 µm per side. Etch factor is verified by microsection per IPC-A-600, and the finished board is qualified to IPC-6012 Class 3. Terminal products are HDI boards with 40/40 µm line/space for mobile processors, automotive camera modules, and implantable medical modules. The bath is regenerated by air sparging at 0.5–1.0 vvm; copper loading above 30 g/L slows seed removal in isolated spaces, and pH below 8.5 increases dry film resist lifting.
When 0.127 mm C19400 copper-iron strip enters a double-sided conveyorized spray etcher, the electronic/EL grade etchant is deliberately operated at high copper loading of 120–150 g/L to stabilize etch rate and suppress excess free ammonia evolution. The bath is held at 52–54 °C, pH 9.0–9.3, and specific gravity 1.17–1.19. Free ammonia concentration is controlled at 4.8–5.2 mol/L, and chloride ion concentration is kept at 150–170 g/L. Half-etch pockets of 40–60 µm per side are produced at etch rates of 25–35 µm/min, while full-thickness tie-bar cuts are performed in the same line. The principal process conflict is maintenance of sidewall geometry: copper loading above 150 g/L raises dynamic viscosity, spray penetration into fine apertures degrades, and lateral undercut increases from 8–12 µm to 15–20 µm per side. Particulate copper hydroxide is controlled with 1 µm absolute filtration. Air sparging at 0.8–1.2 vvm regenerates cupric ion; air flow above 1.5 vvm volatilizes free ammonia, pH falls below 8.8, and dry film resist lifting occurs. Terminal products are QFN, DFN, and SOP leadframes with exposed pad pockets and locking features, inspected to JEDEC package outline criteria and ASTM B152/B152M for C19400 strip.
A 650 mm wide web of 25 µm PET carrier with 3–5 µm sputtered copper is processed at 40–45 °C to prevent polyester shrinkage. The electronic/EL grade alkaline etchant is run with copper loading below 20 g/L, pH 8.2–8.6, and free ammonia 4.0–4.5 mol/L. The roll-to-roll line integrates a 20 m combined etch-rinse chamber, web tension of 80–120 N, and D.I. water rinsing at 18 MΩ·cm. Etch time is set to 20–35 s, sufficient for complete removal of 3–5 µm copper while maintaining a line width tolerance of ±1 µm at 5 µm designed width. The primary failure mode is web shrinkage above 50 °C, causing registration drift between photoresist opening and etched mesh; pH below 8.0 attacks the adhesion-promotion layer and reduces peel strength. Adhesion is verified by 90° peel testing per ASTM D3330/D3330M. Terminal products are transparent conductive copper mesh for capacitive touch sensors in automotive center stacks, wearable displays, and smart packaging. Final circuit continuity is confirmed with 4-wire resistance measurement. Published data for this specific PET grade and mesh geometry is limited.
Photochemically machined apertures in 0.05–0.25 mm oxygen-free copper and Cu-Fe-P alloys are etched in double-sided spray machines with dry-film photoresist. The electronic/EL grade etchant is maintained at 47–49 °C, pH 8.7–9.1, copper loading 60–90 g/L, free ammonia 4.5–5.0 mol/L, and chloride 140–160 g/L. Through-etch time for 0.1 mm OFHC copper is typically 3–4 min at 2.0–2.5 bar spray pressure. The critical process conflict is carbonate accumulation from atmospheric CO₂ absorption, which raises pH, lowers etch rate, and causes resist sloughing; a bleed-and-feed rate of 5–10% of bath volume per shift controls carbonate build-up. Dimensional tolerance is held to ±25 µm on features below 100 µm, verified by optical coordinate measurement and accepted under ISO 2768-1 fine. The bath must not be used for aluminum or zinc features because dissolved copper plates onto those metals by galvanic displacement. Terminal products include RF shielding cans, encoder discs, stencil apertures, and precision shims. Qualification follows customer drawings; published data for this specific alloy-etched geometry is limited.
At wafer level, a 300 mm wafer carrying 0.3–0.5 µm copper seed remaining after pillar plating is processed at 25–30 °C. The electronic/EL grade alkaline etchant is diluted to copper loading below 10 g/L, pH 8.6–9.0, and free ammonia 3.5–4.0 mol/L. Spray or puddle tools remove the seed in 30–60 s without attacking Ti or TiW under-bump metallurgy. Extended exposure beyond 60 s produces measurable sidewall attack on copper pillars with 20–40 µm height. The etchant is filtered through 0.2 µm absolute membranes and blended with 18 MΩ·cm D.I. water. Trace metal specifications are critical: sodium is controlled below 1 ppm, iron below 0.5 ppm, and nickel below 0.1 ppm on supplier certificates of analysis, using SEMI C8 grade ammonium hydroxide as raw material. Terminal products are copper pillar bumps and redistribution layer fan-out structures for flip-chip packages. Equipment operation follows SEMI S2. The principal incompatibility is with oxidized copper; cupric ion depletion shifts the etch rate and creates non-uniform seed removal.
For direct bonded copper substrates carrying 0.2–0.3 mm electrodeposited copper on Al₂O₃ or AlN ceramic, the electronic/EL grade etchant is operated at 50–54 °C, pH 9.0–9.4, copper loading 140–170 g/L, and specific gravity 1.18–1.20. Free ammonia is held at 5.0–5.5 mol/L, and chloride concentration is maintained at 160–180 g/L. On thick copper, the etch rate is 30–40 µm/min; a 0.3 mm layer is cleared in 7.5–10 min. The etch factor is constrained to 2.0–2.5 because of the thickness-to-line-width ratio, and conductor widths below 200 µm require compensate-and-etch design rules. Ceramic edge chipping and copper overhang occur when conveyor speed is below 1.0 m/min or spray pressure exceeds 3.0 bar. The etchant is replenished with ammonia when pH falls below 8.9 and by bleed-and-feed when copper exceeds 170 g/L. Terminal products are IGBT and SiC power module substrates, qualified under AQG 324 for module reliability. The use of concentrated chloride sources with AlN substrates requires etch-rinse neutrality checks to prevent aluminum nitride surface attack during subsequent handling.
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Alkaline Etchant Electronic/EL Grade, designated AE-EL 2000, is an ammoniacal copper etchant formulated for subtractive patterning of fine-line copper circuitry in printed circuit board manufacturing. The product is used in horizontal conveyorized spray etching where line/space geometries below 50 μm pitch are processed. Representative lot-release data list a copper concentration of 130–160 g/L, chloride 180–220 g/L, pH 8.6–9.2 at 25 °C, and specific gravity 1.10–1.12. In comparison with technical-grade ammoniacal etchants, the Electronic/EL grade imposes cation impurity ceilings of < 1 ppm total transition metals and < 0.5 ppm sodium, as determined by ICP-MS per ASTM D5673-16. The product is compatible with tin/lead etch resists and alkaline-stable organic photoresists.
Use of the Electronic/EL grade in printed circuit fabrication is governed by two constraints: metallic impurities must remain below thresholds that affect electrical leakage and dendrite formation, and insoluble particulates must be low enough to prevent nozzle deposition. Plant-scale failure modes observed on horizontal spray etchers include pH drift caused by ammonia volatilization, copper loading exceeding solubility limits, and chloride imbalance from drag-out losses. These failure modes are not uniform across etch chemistries; the ammoniacal system is selected where the resist compatibility of acid cupric chloride is insufficient.
Acid cupric chloride and ferric chloride etchants attack tin and lead, which restricts their use in outer-layer circuits that employ tin/lead resists. Alkaline etchants operate at pH values where tin/lead surfaces passivate, allowing the etch to proceed without destroying the metal resist. This property permits direct etching of outer-layer panels with tin/lead etch resists and reduces process steps compared with photoresist-only acid etching. In horizontal spray systems, the etch rate on 18 μm electrolytic copper foil is reported in supplier technical bulletins at 25–45 μm/min when the bath is maintained at 48–52 °C and nozzle pressure is held at 1.2–2.8 bar. Published data for this specific configuration is limited; validation on the specific etcher model is required. The bath should be monitored by glass-electrode pH measurement and Coriolis density meter for specific gravity.
Technical-grade ammonium chloride and ammonium hydroxide feedstocks can carry sodium, potassium, calcium, magnesium, iron, nickel, and chromium at levels that generate residues on printed circuit board surfaces. These residues can reduce surface insulation resistance under humid bias conditions such as 85 °C/85 % RH, as evaluated by IPC-TM-650 Method 2.6.3.7. Electronic/EL grade material is filtered and specified to limit these elements to sub-ppm concentrations. A representative specification comparison is shown below; lot-specific certificate-of-analysis values should be confirmed before tank make-up.
| Parameter | Electronic/EL Grade AE-EL 2000 | Technical-Grade Ammoniacal Etchant | Test Designation |
|---|---|---|---|
| pH at 25 °C | 8.6–9.2 | 8.3–9.0 | ASTM E70-07 |
| Specific gravity at 25 °C | 1.10–1.12 | 1.09–1.14 | ASTM D4052-18 |
| Copper concentration | 130–160 g/L | 100–180 g/L | ASTM D1688-17 |
| Chloride concentration | 180–220 g/L | 160–230 g/L | ASTM D512-12 |
| Sodium | < 0.5 ppm | < 50 ppm | ASTM D5673-16 |
| Iron | < 0.3 ppm | < 20 ppm | ASTM D5673-16 |
| Calcium and magnesium combined | < 0.5 ppm | < 15 ppm | ASTM D5673-16 |
The sodium and calcium differences are operationally significant. In technical-grade material, calcium and magnesium precipitate as carbonate and oxalate salts in the spray chamber and on heater surfaces. In Electronic/EL grade material, the combined calcium and magnesium burden is specified below 0.5 ppm, which reduces scale deposition and nozzle blockage. This distinction is not visible in pH or copper concentration but affects pattern yield on high-density interconnect panels. Trace-metal limits are verified by inductively coupled plasma mass spectrometry per ASTM D5673-16 after a 10:1 dilution in 2 % nitric acid. The Electronic/EL grade is also routinely checked for particulate by light-scattering particle counter at a threshold of > 0.5 μm, with acceptance criterion < 25 particles/mL. This particulate limit matters in high-density interconnect processing because nozzle orifices of 0.8 mm to 1.2 mm diameter can accumulate particles and reduce impingement uniformity.
Ammoniacal etchants lose free ammonia through evaporation at the operating temperature. A drop in pH from 9.0 to 8.4 decreases the etch rate and increases undercut. Plant-scale observation on a 2.4 m effective etch chamber with exhaust flow of 1,200–1,800 m³/h indicates pH sag occurs within 6–8 h unless automatic ammonia injection is used. Copper loading changes specific gravity, and above 170 g/L the bath approaches the solubility limit of the copper ammonium complex. At specific gravity above 1.15, copper-rich solids can form in cooling loops, leading to nozzle clogging and visible striations. The operating window for this grade is therefore typically maintained at 130–160 g/L copper, 180–220 g/L chloride, pH 8.6–9.2, and specific gravity 1.10–1.12. These ranges are consistent with supplier technical bulletins for ammoniacal etching systems.
Closed-loop regeneration is used in high-throughput lines to maintain these ranges. Copper is recovered by electrowinning from a recirculating slipstream at 4–8 A/dm² with insoluble anodes, while ammonia and chloride are replenished through a venturi saturator. Because the Electronic/EL grade limits calcium and magnesium below 0.5 ppm, the insoluble anode surfaces and spray bars show lower scale deposition than in technical-grade systems. The use of untreated hard water for dilution should be avoided; deionized water with resistivity above 1 MΩ·cm is recommended.
Etch factor, defined as the ratio of vertical etch depth to lateral undercut per side, determines whether a given printed circuit design can be retained after etching. For 50 μm line features on 18 μm copper foil, the Electronic/EL grade is typically operated to an etch factor of 3.0–4.5, while acid cupric chloride systems may exhibit lower values. The following comparative process envelope is derived from supplier bulletins and equipment compatibility data; published data for this specific configuration is limited and plant-specific validation is required.
| Property or Process Condition | Alkaline Electronic/EL Grade AE-EL 2000 | Acid Cupric Chloride Etchant | Relevance |
|---|---|---|---|
| Tin/lead resist compatibility | Compatible | Incompatible; dissolves tin/lead | Metal-resist processing |
| Operating temperature | 48–52 °C | 45–55 °C | Horizontal spray etcher |
| Nozzle pressure | 1.2–2.8 bar | 1.0–2.5 bar | Impingement uniformity |
| Copper loading before precipitation | 130–170 g/L | 80–120 g/L | Bath life |
| Etch rate on 18 μm foil | 25–45 μm/min | 15–30 μm/min | Throughput |
| Typical undercut per side at 50 μm line | 2–4 μm | 5–10 μm | Line width retention |
The alkali pH of the ammoniacal system passivates tin/lead resist surfaces and permits the use of thin copper foils without resist breakdown. In contrast, acid cupric chloride attacks tin/lead and is largely restricted to photoresist-defined inner-layer circuits. The alkaline system also holds more copper in solution before precipitation, which extends bath life and reduces waste volume. These differences make the Electronic/EL grade suitable for outer-layer etched features where conductor width and spacing are below 50 μm.
AE-EL 2000 is supplied as a ready-to-use liquid in 20 L cubitainers and 200 L HDPE drums. The product is prepared by blending electronic-grade ammonium hydroxide with high-purity ammonium chloride and dissolving copper metal or copper(II) oxide under controlled pH to form the tetraammine complex. Because the formulation is ammonia-based, vapor pressure increases with temperature; containers should be vented and stored in corrosion-resistant cabinets. Waste etch solution is treated by raising pH to 10.5 to precipitate copper oxide, or by closed-loop electrowinning. The high copper holding capacity of the ammoniacal system reduces waste volume relative to acid cupric chloride, where solubility limits force more frequent dumping.
Operational boundaries must be observed to maintain the Electronic/EL grade within its specified impurity and performance envelope. The product should not be mixed with sulfuric acid, hydrogen peroxide, or other oxidizing acids, because exothermic decomposition and chlorine release can occur. Storage should be maintained between 5 °C and 35 °C in vented HDPE containers; freezing at temperatures below 0 °C can cause crystal formation and subsequent nozzle blockage. Do not dilute with hard water or reclaimed water containing more than 10 ppm calcium or magnesium. The product is incompatible with strong oxidizers and with acid cupric chloride baths; cross-contamination can precipitate copper chloride and destabilize the ammoniacal complex. When pH falls below 8.0, the etch rate becomes non-uniform, and the bath should be corrected with anhydrous ammonia before further processing.
