| HS Code | 775584 |
| Chemical Composition | Nickel sulfamate, nickel chloride, boric acid |
| Appearance | Clear green liquid |
| Nickel Content | Approximately 100-150 g/L |
| Ph | 3.5 - 4.5 |
| Specific Gravity | 1.20 - 1.30 at 25°C |
| Operating Temperature | 40 - 60°C |
| Cathode Current Density | 1 - 10 A/dm² |
| Deposition Rate | 10 - 25 µm/hour |
| Metallic Impurities | Cu < 5 ppm, Fe < 10 ppm, Zn < 5 ppm |
| Electrical Conductivity | High conductivity suitable for electronics plating |
As an accredited Nickel Plating Solution Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | This Nickel Plating Solution Electronic/EL Grade is supplied in a 1-gallon (3.78 L) high-density polyethylene bottle, safety sealed and labeled. |
| Container Loading (20′ FCL) | 20′ FCL loaded with UN-approved drums/IBCs, securely palletized, labeled, ventilated, segregated from incompatible materials for safe transport. |
| Shipping | Ship Nickel Plating Solution Electronic/EL Grade as a hazardous, corrosive liquid. Pack in UN-approved containers, seal tightly, and use proper hazard labels. Segregate from incompatible materials, ensure ventilation, and follow ground transport or air cargo regulations. Include safety data sheet, emergency contacts, and spill-response documentation for compliance. |
| Storage | Store in tightly sealed, original containers in a cool, dry, well-ventilated area away from incompatible materials like strong oxidizers, acids, and alkalis. Avoid direct sunlight and temperature extremes. Use corrosion-resistant secondary containment. Keep segregated from food and drinking water. Inspect for leaks regularly. Follow manufacturer’s SDS for specific EL-grade requirements. |
| Shelf Life | Store in tightly sealed container at room temperature. Shelf life typically 6–12 months from date of manufacture. |
In electroless nickel immersion gold processing, the nickel layer functions as the primary barrier and soldering underlayer, while the immersion gold layer preserves solderability until assembly. The electronic/EL grade bath is operated at a nickel ion concentration of 4.8–5.6 g/L as Ni²⁺, sodium hypophosphite at 20–28 g/L, and a lactic–succinic–malic acid complexing system sufficient to maintain nickel solubility at pH 4.4–4.8. Bath temperature is controlled to 82–86 °C in a vertical in-line immersion module with external plate heat exchange and continuous 0.2 µm absolute filtration. Under these conditions, deposition rate is held between 8–12 µm/hr and the resulting nickel film contains 9–12 wt% phosphorus. Load is maintained between 0.3–0.8 dm²/L to limit spontaneous plate-out in the tank and rack hardware. Copper contamination above 10 mg/L in the working bath depresses bath stability and increases the incidence of skip plating on fine-pitch copper pads, so electronic-grade solution is replenished only with high-purity nickel salts and hypophosphite that carry trace iron, zinc, and lead below 1 mg/L each. The nickel thickness on high-density interconnect boards is controlled to 3.5–5.5 µm in accordance with IPC-4552A, while immersion gold thickness is limited to 0.04–0.10 µm for soldering surfaces and 0.08–0.15 µm where aluminum wire bonding is specified. Solderability is verified by wetting balance per J-STD-003 using SAC305 paste and by thermal stress at 260 °C through three reflow cycles. The high-phosphorus microstructure reduces black-pad corrosion at the nickel–gold interface compared with medium-phosphorus deposits. The terminal products are smartphone mainboards, tablet HDI boards, and camera-module flex circuits where the ENIG surface must survive multiple lead-free reflow excursions without exposing copper-tin intermetallic compounds through the nickel barrier.
For mixed-bonding packages requiring both gold-wire and solder-joint capability, medium-phosphorus electroless nickel is deposited before autocatalytic palladium and immersion gold. The nickel bath is run at a reduced nickel ion concentration of 4.0–5.0 g/L, sodium hypophosphite 18–25 g/L, pH 4.6–5.2, and operating temperature 78–84 °C, producing a deposit with 5–9 wt% phosphorus. The lower temperature suppresses nodulation on fine-pitch copper traces and allows deposition to be stopped at the IPC-4556 range of 3.0–6.0 µm. Electroless palladium follows at 0.05–0.15 µm, and immersion gold is controlled to 0.03–0.10 µm over the palladium. A horizontal in-line wet process with cascade rinsing is required, and the rinse water is maintained at 10–18 MΩ·cm resistivity at 25 °C with nitrogen blanketing to prevent nickel oxidation between steps. Palladium drag-in into the nickel bath above 5 mg/L and copper carryover from the microetch step are controlled by air knives and rinse-water conductivity monitoring. The resulting stack is applied to BGA package substrates, package-on-package interposers, and mixed-signal modules. Solder joint reliability is confirmed by ball shear after preconditioning, and gold-wire bond integrity is checked by wire-pull testing against the applicable package qualification plan. The medium-phosphorus nickel layer remains thick enough to block copper diffusion during 245–260 °C reflow while avoiding the hardening effect of very high phosphorus at the nickel–palladium interface.
As an under-bump metallurgy diffusion barrier, the electroless nickel layer is positioned directly over a zincated aluminum pad, and the phosphorus content is maintained between 6–9 wt% to limit nickel-tin intermetallic compound growth during Sn-Ag-Cu reflow. The wafer-level bath is operated with Ni²⁺ at 4.8–5.6 g/L, hypophosphite at 20–26 g/L, pH 4.5–5.0, and temperature 80–85 °C. Batch wafer plating tools use either single-wafer spin processing with pump-fed chemistry or recirculated bath immersion with megasonic agitation at 300–500 kHz to remove hydrogen bubbles from recessed pad openings. Nickel thickness is controlled to 3–5 µm, and wafer-to-wafer thickness variation is kept below ±5% through periodic coulometric thickness checks at nine fixed measurement points per wafer. The deposit may receive immersion gold for oxidation protection or may proceed directly to flux application and bump reflow. The terminal use is under-bump metallization for flip-chip bumped wafers in automotive radar, power management ICs, and RF front-end modules. Compliance is anchored to ASTM B733 for autocatalytic nickel-phosphorus coatings, and the package is subjected to JEDEC moisture sensitivity level preconditioning and temperature cycling after bumping. Operational failure occurs when the zincate seed layer is incomplete at the pad edge; this produces localized nickel lifting, which is detectable by optical inspection after plating and by tape testing of the plated wafer before bump attach.
On sintered alumina and aluminum nitride ceramic bodies, the as-fired surface is roughened by thermal or chemical etching and then activated with a stannous chloride/palladium chloride sequence before electroless nickel application. The nickel bath for ceramic termination is held at 82–88 °C, pH 4.8–5.5, Ni²⁺ at 4.5–6.0 g/L, and hypophosphite at 20–30 g/L. Deposit thickness is controlled to 1.5–4.0 µm with phosphorus at 5–10 wt%. Barrel plating equipment operating at 1–3 rpm with small cylindrical mixing media prevents chip stacking and edge chipping during plating. The nickel termination forms the solderable base for subsequent tin or gold overplating on chip resistors, multilayer ceramic capacitors, and insulated metal substrate power modules. Adhesion is verified by destructive torque and shear testing adapted from MIL-STD-883 method 2019.9. RoHS 2011/65/EU compliance is satisfied without cadmium or lead in the electroless nickel system; REACH SVHC screening is applied to the complexing agents and stabilizers. A critical process limit is that the ceramic body must not retain plating solution in microcracks after the activation step, so post-nickel rinse water is monitored at the final cascade to exceed 12 MΩ·cm at 25 °C. Failure to maintain this rinse standard produces ionic residues at the ceramic–nickel interface and reduces insulation resistance on high-value chip resistor bodies.
Aluminum bond pads and shield housings are prepared by a double zincate immersion step because direct electroless nickel deposition on aluminum produces oxide-contaminated interfaces and blistering. The first zincate film is deposited in an alkaline solution at 18–25 °C, stripped in 30–50 vol% nitric acid, and followed by a second thinner zincate layer immediately before nickel. The electronic-grade nickel bath is then run at 80–85 °C, pH 4.6–5.0, Ni²⁺ at 4.5–5.5 g/L, and hypophosphite at 20–28 g/L, producing 3–6 µm of nickel with 8–11 wt% phosphorus on the activated aluminum surface. High-phosphorus content is selected for low porosity and corrosion resistance on lid and cavity packages used in outdoor and automotive environments. Adhesion is verified by crosshatch tape testing per ASTM D3359 and by thermal shock testing per MIL-STD-883 method 1011.9. The terminal products are organic-sealed high-frequency modules and frequency-selective shields in 5G millimeter-wave front ends. The operational boundary is that the second zincate film must not exceed 0.3 µm; thicker zincate layers dissolve unevenly in the acidic nickel bath and create localized adhesion loss at the aluminum interface. Nickel thickness below 3 µm is not used in this configuration because porosity increases rapidly on rough aluminum pad edges and allows galvanic attack in humid operating environments above 85% RH.
For microelectromechanical systems, low-phosphorus electroless nickel with 1–4 wt% phosphorus is deposited selectively on sacrificial layers or used as a structural reinforcement after release. The bath control window is narrower than for packaging applications: Ni²⁺ is held at 4.0–5.0 g/L, hypophosphite at 16–24 g/L, pH 5.8–6.4, and temperature 72–78 °C. Lower phosphorus content shifts film stress from compressive toward tensile and changes the effective elastic modulus of the plated structure, so deposition parameters are adjusted only after wafer bow measurement. Nickel thickness is maintained between 0.5–2.5 µm on proof-mass, cantilever, and interdigitated sensor structures. Published data for this specific configuration is limited; therefore, film stress and stiction behavior must be characterized on witness wafers before a production batch is committed. The terminal use is inertial sensors, micro-relay contact pads, and capacitive switches, where the nickel layer must maintain dimensional stability after through-wafer etching and release. The deposit is not used as a corrosion barrier without an additional noble metal overcoat in humid environments above 85% RH. Compliance references include ASTM B733-20 for autocatalytic nickel-phosphorus coatings and ISO 4527:2003 for engineering nickel deposits. The principal failure mode on MEMS structures is hydrogen embrittlement of thin cantilevers, controlled by the lower operating temperature and by intermittent reverse pulse agitation during the initial 0.5 µm of deposition.
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The product designation Nickel Plating Solution Electronic/EL Grade is used here as the vendor model identifier; the exact formulation is defined by the lot-specific technical data sheet and certificate of analysis. In electrolytic form, the electrolyte is supplied as a nickel sulfamate-based concentrate with a nominal nickel metal content of 180 g/L to 220 g/L in the replenishment concentrate and a working-bath dilution to 75–110 g/L nickel after makeup. The electronic/EL classification denotes a contaminant-controlled composition intended for low-porosity nickel deposits on copper, copper alloy, nickel-iron, and Fe-29Ni-17Co alloys in applications where solderability, wire-bonding cleanliness, and deposit stress control are critical. The as-supplied liquid is filtered to 0.2 µm absolute and is typically packaged in ≤ 200 L HDPE drums or 1000 L IBC containers. Storage is limited to 5–30 °C under inert or dry-air headspace; crystallization at lower temperatures requires slow redissolution with circulation rather than direct steam injection.
The primary performance distinction of the EL grade is deposit stress control at thicknesses above 25 µm, where high tensile stress in conventional Watts deposits leads to microcracking and lift-off. The sulfamate-based formulation with low chloride and no sulfur-bearing brighteners produces a deposit elongation of 8–20% over a 50 mm gauge length when tested on a tensile stage, compared with 2–5% for bright decorative nickel. Internal stress is measured on a spiral contractometer with a stainless-steel helix; a tensile stress below 70 MPa is the release range for most connector and semiconductor leadframe applications. The electrolyte is suitable for rack, barrel, and high-speed selective plating, but barrel-plating current density must be derated to 0.5–2 A/dm² because of current shielding inside the barrel and slower solution exchange.
The working bath is made up with nickel sulfamate, boric acid, and a controlled low-chloride addition. Nickel ion is maintained between 75 g/L and 110 g/L, with boric acid at 30–45 g/L as a pH buffer and cathode-film modifier. Chloride is typically limited to 0–5 g/L; the lower chloride limit reduces anode sludge formation and minimizes tensile stress in deposits intended for thermal cycling. Bath pH is maintained at 3.5–4.5, adjusted only with sulfamic acid or nickel carbonate; use of sulfuric acid is discouraged because sulfate accumulation raises the crystallization temperature and lowers limiting current density. Temperature is held at 50–65 °C. Cathode current density is specified from 2–10 A/dm² for rack plating and from 10–30 A/dm² for high-speed selective cells with turbulent flow. At the upper current-density range, the bath requires auxiliary eductor agitation and either moving cathode workpieces or strip speed above 2 m/min to avoid nodular growth.
The cathode efficiency of the sulfamate bath is typically 97–99% at 5 A/dm² and 55 °C, as determined by gravimetric thickness checks against coulometric measurements. Cathode efficiency decreases below 95% when pH falls below 3.3, because hydrogen evolution competes with nickel reduction; the resulting hydrogen uptake can embrittle high-strength substrates. Filtration is maintained through 0.2 µm absolute-rated polypropylene depth filters at 4–10 tank-volume turnovers per hour. The bath is agitated by low-pressure air from an oil-free blower only when chloride is present; air agitation above 0.5 L/min per square metre of bath surface oxidizes sulfite and organic contaminants but can also increase iron drag-out from steel components.
| Parameter | Specification | Control equipment or test method |
|---|---|---|
| Nickel metal | 75–110 g/L working bath; 180–220 g/L concentrate | ICP-OES or AAS |
| Boric acid | 30–45 g/L | Wet chemistry titration |
| Chloride | 0–5 g/L | Argentometric titration or ion chromatography |
| pH | 3.5–4.5 | Calibrated glass electrode |
| Temperature | 50–65 °C | RTD with recorder |
| Cathode current density | 2–10 A/dm² rack; 10–30 A/dm² high-speed | Rectifier ammeter and shunt |
| Filtration | 0.2 µm absolute | Polypropylene depth filter |
| Solution turnover | 4–10 tank volumes/h | Flow meter in filter loop |
In reel-to-reel selective plating of copper-alloy leadframes, the solution is pumped from a polypropylene sump through isolated anode chambers with titanium-mesh baskets containing sulfur-depolarized nickel rounds. The bath is returned through a 0.2 µm depth filter and a heat exchanger to maintain ±1 °C control at the plating cell. Under these conditions, a deposit thickness of 2–5 µm is produced on selectively exposed surfaces at line speeds of 1.5–6 m/min. Solderability after 8 h steam aging is assessed per J-STD-003 wetting balance at 245 °C; the deposit must exhibit zero dewetting on connector lead areas. The EL grade differs from standard sulfamate baths in that the carbon treatment interval is extended by controlling anode dissolution and excluding wetting agents that elevate total organic carbon. Bath samples are pulled every 8 h of production for pH, boric acid, nickel, chloride, and surface-tension checks; the analytical results are trended against SPC limits rather than released by visual clarity alone.
Barrel plating of small connector pins with an EL-grade sulfamate bath requires load size not exceeding 60% of barrel volume, and mechanical work is reversed every 4–6 min to prevent shadowing. Deposit thickness variation across a barrel load is typically ± 15% when the barrel is rotated at 6–10 rpm; tighter distributions require immersed dangler systems and a reduced current density at the start of the cycle. The solution is used without cetylpyridinium or sodium lauryl sulfate wetting agents in fine-pitch applications because organic residues on the deposit can increase contact resistance; if surface wetting is required, a non-ionic low-foam surfactant is added at less than 0.1 mL/L and monitored by surface-tension checks.
Conversion from a conventional sulfamate bath to the electronic/EL grade requires a clean-out of the sump, filter housing, heat exchanger, and anode bags to remove sludge, iron, and old organic breakdown products. Residual chloride from the previous bath must be below 100 mg/L before the EL grade is introduced; otherwise the low-stress deposit specification may be exceeded. The principal differences observed in production are lower particulate counts on the cathode surface, lower codeposited sulfur, and narrower internal-stress distribution. Deposit sulfur content is maintained below 0.005 wt% where the bath is operated without brighteners; this is measured by combustion analysis per ASTM E1019. Tensile stress in the deposit is determined by spiral contractometer or by the bent-strip method; the typical range for the EL grade is 0–70 MPa tensile without organic stress reducers. For comparison, decorative Watts nickel with sulfur-bearing brighteners can exhibit tensile stress above 170 MPa and sulfur content above 0.03 wt%, making the deposit unsuitable for thermal-cycle or solder-assembly environments.
Existing rectifiers with ripple above 5% can produce rough, slightly sulfur-stained deposits from this electrolyte, particularly at high current density. The EL grade does not mask the effect of poor current control; therefore, three-phase full-wave rectification with ripple below 5% is specified for leadframe and edge-connector lines. The bath is sensitive to drag-in of copper from upstream strike tanks; copper levels above 10 mg/L cause visible darkening in low-current-density areas and reduce solder wetting. Low-current-density dummy plating at 0.2–0.5 A/dm² on corrugated steel cathodes removes copper and zinc in production; if the contamination exceeds 25 mg/L, a selective ion-exchange or partial bath discard is required.
| Parameter | Electronic/EL sulfamate | Standard sulfamate | Decorative Watts bright nickel |
|---|---|---|---|
| Nickel metal | 75–110 g/L | 75–110 g/L | 60–90 g/L |
| Chloride | 0–5 g/L | 2–8 g/L | 9–18 g/L |
| Sulfate | Absent or trace | Absent or trace | 150–190 g/L |
| Total organic carbon | <200 mg/L as supplied | <1000 mg/L | <2000 mg/L |
| Sulfur in deposit | 0.003–0.008 wt% | 0.010–0.020 wt% | 0.030–0.080 wt% |
| Internal stress | 0–70 MPa tensile | 70–140 MPa tensile | 140–260 MPa tensile |
On printed circuit board edge-connector lines using isolated anode chambers, the EL grade is applied at 2–5 A/dm² to produce a semi-bright deposit thickness of 1.25–5 µm over copper. After plating, adhesion is verified by bend testing and tape pull per ASTM B571; porosity is screened by the ferroxyl test or by sulfur dioxide exposure. Panels with visible nodules or edge build-up are traced to insufficient filtration, improper rectifier ripple above 5%, or airborne debris. The bath does not contain organic brighteners of the aromatic sulfonate class that codeposit sulfur, so the need for periodic carbon treatment is lower than in Watts lines; however, if the solution is contaminated by drag-in from a bright nickel strike, carbon treatment and low-current-density dummying at 0.2–0.5 A/dm² are required to restore metallic impurity and TOC targets.
When the EL grade is compared with electroless nickel-phosphorus deposits, the electrolytic deposit contains no codeposited phosphorus, which benefits solder wetting and wire bonding, but it does not plate recesses with the same thickness uniformity as an autocatalytic bath. Throwing power for the EL grade is controlled by cathode efficiency, solution conductivity, and cell geometry; in low-current-density zones below 1 A/dm², deposit thickness may fall below specification unless auxiliary anodes or pulse reverse are used. Electroless nickel deposits of 4–10 wt% phosphorus produce higher hardness but lower inherent solderability after thermal aging. The EL grade is selected where low electrical resistivity, low sulfur codeposition, and sulfamate ductility dominate over uniformity on non-line-of-sight surfaces.
Sulfur-depolarized nickel anode rounds in titanium baskets require a minimum chloride concentration of 2 g/L to prevent anode passivation at current densities above 2 A/dm²; below that level, the anode potential rises, oxygen evolution increases, and the bath may form a fine black sludge that deposits as pit roughness. The EL grade is formulated at the lower end of the chloride range because chloride raises deposit tensile stress; therefore, anode area is maintained at 1.5–2.0 times the cathode area in rack operations and at 2.0–3.0 times in high-speed cells. Insoluble mixed-metal oxide anodes with sulfamate-compatible anolyte chambers eliminate chloride dependence but require separate pH control and periodic removal of orthophosphate if phosphorus-based anolyte conditioners are used. Published data for this specific configuration is limited, so anode selection is usually confirmed by Hull cell panels and anode polarization scans rather than by reference data alone.
The as-shipped electrolyte is released against a certificate of analysis that typically limits copper, zinc, lead, iron, chromium, and aluminum to low single-digit mg/L levels because these species influence deposit solderability, porosity, and wire-bonding yields. Metallic impurities are determined by ICP-MS or AAS; the lower detection limit for copper and zinc is commonly 0.1 mg/L. Total organic carbon is held below 200 mg/L in the as-supplied product, and the liquid is filtered through 0.2 µm absolute-rated media; this reduces particulate-related pit formation on leadframe and connector surfaces. The product is also specified to contain no intentionally added arsenic, antimony, or sulfur-bearing brighteners. For engineering nickel deposits covered by ISO 4526 or ASTM B689, the plated article is subject to thickness verification by coulometric or microscopy methods, adhesion testing, and neutral salt spray exposure per ASTM B117 if corrosion resistance is specified.
Bath aging in the EL grade is governed by sulfamate hydrolysis, which becomes significant above 70 °C and at low pH below 3.2. Hydrolysis releases sulfate and ammonium; sulfate increases conductivity but raises the tendency for deposit stress to shift tensile, while ammonium accumulates and can reduce cathode efficiency. In well-controlled production at 50–60 °C, sulfate accumulation is typically 1–3 g/L per 1000 A·h/L; exceeding this range indicates a hot spot in the heat exchanger or localized boiling on immersion heater surfaces. The analytical release criteria therefore include sulfate, ammonium, and total organic carbon in addition to metallic contaminants, because their interaction determines the long-term deposit reproducibility of the electronic/EL grade.
Under pulse-reverse plating conditions with a peak current density of 8–15 A/dm² and reverse duty cycles below 10%, the EL grade improves throwing power in connector recesses without the addition of sodium or potassium salts that leave conductive residues on high-frequency housings. The electrolyte is operated at the lower end of the pH range near 3.5 when chloride is absent, but pH below 3.3 causes boric acid consumption and increased hydrogen evolution at the cathode; pH above 4.8 risks nickel hydroxide precipitation and nodule growth. The bath should not be mixed with amine-based brighteners, sulfur-bearing carrier systems, or hypophosphite-containing electroless nickel solutions; sulfamate hydrolysis accelerates above 70 °C, releasing sulfate and ammonium that alter deposit stress and reduce cathode efficiency. Continuous filtration at 4–10 tank-volume turnovers per hour is required for high-speed operations; interrupted filtration during production is a common field failure mode that produces star-dust roughness on fine-pitch connectors.
