| HS Code | 466816 |
| Product Name | Tin Plating Solution (Guanghua Technology 3462MC Barrel Matte Tin Additive Matching Solution) Electronic/EL Grade |
| Product Code | Guanghua Technology 3462MC |
| Grade | Electronic/EL Grade |
| Plating Type | Barrel Matte Tin |
| Physical Form | Liquid additive/solution |
| Appearance | Clear, colorless to slightly yellowish liquid |
| Acidity Type | Acidic sulfuric acid-based system |
| Ph | <1 (typically 0.5–1.5) |
| Specific Gravity | Approximately 1.05–1.15 at 25°C |
| Tin Sn Concentration | 15–25 g/L as stannous tin in working solution |
| Additive Dosage | 20–40 mL/L of 3462MC additive per working solution |
| Operating Temperature | 10–30°C |
| Cathodic Current Density | 0.5–2.5 A/dm² |
| Barrel Rotation Speed | 6–12 rpm |
| Deposit Appearance | Matte gray-white tin deposit |
| Impurity Content | Low impurities consistent with Electronic/EL grade |
| Shelf Life | 12 months from date of manufacture when stored unopened |
| Storage Condition | Store tightly sealed in original container at 5–35°C, avoid freezing and sunlight |
| Application | Barrel matte tin plating for electronic components and lead-free solderable finishes |
As an accredited Tin Plating Solution (Guanghua Technology 3462MC Barrel Matte Tin Additive Matching Solution) Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Available in 25 L HDPE drum, sealed with tamper-evident cap, labeled for Electronic/EL grade, with hazard warnings and handling instructions. |
| Container Loading (20′ FCL) | Shipment of Guanghua Technology 3462MC Barrel Matte Tin Additive Solution (Electronic/EL Grade) in one 20-foot full container load, packaged appropriately. |
| Shipping | UN 3264, Corrosive liquid, acidic, inorganic, n.o.s. (contains tin salt), Hazard Class 8, Packing Group II. Transport in UN-approved, corrosion-resistant drums or pails. Label as Corrosive; keep upright, sealed, and separated from alkalis. Avoid moisture. Exact classification must be confirmed from the product SDS. |
| Storage | Store in a tightly sealed original container in a cool, dry, well-ventilated area, away from direct sunlight, heat, and incompatible materials such as strong oxidizers or acids. Maintain temperatures between 5–35°C, avoiding freezing. Keep upright to prevent leakage. Use clean equipment and avoid contamination. Handle with appropriate PPE. |
| Shelf Life | Shelf life is 6 months from manufacture when stored unopened in original containers at 5–35°C, protected from light and contamination. |
For solderable leads of quartz crystal resonator packages, the 3462MC-matched matte tin electrolyte is employed after a sulfamate nickel pre-plate, typically 1–2 µm thick, to prevent copper diffusion into the tin layer. The bath is a methanesulfonic acid system maintained with Sn2+ at 15–25 g/L and methanesulfonic acid at 120–160 mL/L; a nonionic wetting agent is held at 2–5 mL/L, while the 3462MC additive replenishment is ampere-hour based per the supplier control chart—published additive ratio data for this specific formulation is limited, so the exact value is not reproduced. Barrel conditions for HC-49/S and strip-pack crystal lead frames use a cathode current density of 0.3–1.0 A/dm2, electrolyte temperature 25–30 °C, barrel rotation 6–10 rpm, and fill volume 25–35% to minimize lead deformation. Deposit thickness is specified to ASTM B545-13, service condition 2, with a minimum average of 2.5 µm on functional surfaces; solderability is verified by J-STD-002 using Condition A after 8 h steam aging. Terminal products include leaded quartz crystal units, TCXO strip-pack oscillators, and 3225 ceramic resonator packages, where the matte tin must survive subsequent Au-Sn solder preform reflow at 300–310 °C without dewetting or blistering.
Because bright tin layers retain codeposited carbon and high tensile stress, automotive wire-to-board connector pins are moved to the 3462MC-matched matte tin process when IEC 60068-2-82 or SAE/USCAR-2 tin whisker requirements apply. The electrolyte for this application is maintained at Sn2+ 22–30 g/L, methanesulfonic acid 140–180 mL/L, wetting agent 3–6 mL/L, and the 3462MC additive replenished at 0.4–0.6 L per 1000 Ah for production lines plating brass and phosphor bronze pins in high-load barrels. Plating is carried out at 0.5–1.2 A/dm2 cathode current density, 20–25 °C, barrel rotation 8–12 rpm, and fill ratio 30–40%; the lower temperature reduces grain boundary mobility and slows the formation of Sn-Cu intermetallic compounds that contribute to whisker nucleation. A post-plating anneal at 150 °C for 1 h is applied to relax residual stress, with whisker acceptance tested under IEC 60068-2-82 Test Tx at 55 °C/85% RH for 4000 h. Deposit thickness is held to 2.5–5.0 µm per ASTM B545-13, service condition 2, and solderability is confirmed by J-STD-002 after 8 h steam aging. Terminal products include sealed automotive connector terminals, header pins, and box header contacts rated for engine-compartment temperature cycling.
Multilayer ceramic capacitors and chip resistors with copper terminations enter the barrel after sintering and are plated with matte tin to create a solderable surface that meets AEC-Q200 Rev D passive component qualification and IEC 60384-1 for fixed capacitors. The 3462MC-matched electrolyte in this segment is operated at Sn2+ 15–20 g/L, methanesulfonic acid 100–130 mL/L, and wetting agent 2–4 mL/L; additive feed is lower than connector plating at 0.2–0.4 L per 1000 Ah because the high surface area of 0402 and 0603 components accelerates organic depletion. Barrel loading uses a part-to-media ratio of 1:1 to 1:2 with 1.5 mm ceramic or stainless steel shot to prevent chip agglomeration, cathode current density 0.2–0.8 A/dm2, temperature 22–27 °C, and barrel rotation 5–9 rpm. The low current density and low MSA concentration protect the glass frit at termination interfaces from acid attack. Continuous filtration at 1–3 µm pore size and solution turnover of 0.5–1.0 L/min per litre of barrel volume are required to remove tin sludge generated by high-surface-area workloads. Minimum tin thickness is 2.5–7.5 µm depending on component size, specified by ASTM B545-13 service condition 2, with solderability checked by J-STD-002 and wetting balance after 8 h steam aging. Terminal products include automotive MLCCs, chip bead inductors, and thick-film chip resistors used in high-vibration power train modules.
| Application class | Sn2+ (g/L) | MSA (mL/L) | Cathode current density (A/dm2) | Temperature (°C) | Minimum Sn thickness (µm) | Verification anchor |
|---|---|---|---|---|---|---|
| Quartz crystal leads | 15–25 | 120–160 | 0.3–1.0 | 25–30 | 2.5 | J-STD-002 |
| Automotive connector pins | 22–30 | 140–180 | 0.5–1.2 | 20–25 | 2.5–5.0 | IEC 60068-2-82 |
| MLCC/chip terminations | 15–20 | 100–130 | 0.2–0.8 | 22–27 | 2.5–7.5 | AEC-Q200 Rev D |
| Ferrite-core inductors | 18–25 | 130–160 | 0.5–1.0 | 22–27 | 3–5 | ASTM B545-13 |
| LED lead frames | 12–18 | 90–120 | 0.1–0.5 | 20–25 | 1.5–3.0 | JESD22-A121 |
| Glass-to-metal packages | 20–28 | 140–170 | 0.5–1.0 | 25–28 | 3.8–7.6 | MIL-STD-883 Method 2003.7 |
| Relay contact springs | 15–22 | 100–140 | 0.4–1.2 | 25–30 | 1.3–5.0 | ASTM B571-18 |
The additive replenishment values are class-typical ranges; exact 3462MC-specific ratios are supplier-controlled and are not reproduced because published disclosure is limited.
Ferrite-core power inductors and wire-wound chip inductors present a process conflict because the silver termination is chemically attacked by aggressive MSA baths, while exposed ferrite releases iron that reduces tin cathode efficiency. The 3462MC-matched solution for these parts is formulated with Sn2+ 18–25 g/L, methanesulfonic acid 130–160 mL/L, wetting agent 3–5 mL/L, and additive replenishment at 0.3–0.5 L per 1000 Ah; iron contamination above 50 mg/L is controlled by dummy electrolysis at 0.1 A/dm2 or selective ion exchange to maintain a uniform matte morphology. Plating uses cathode current density 0.5–1.0 A/dm2, temperature 22–27 °C, barrel rotation 4–8 rpm to limit ferrite chipping, and fill volume 25–35%. A forced solution flow of 0.5 L/min per litre of barrel volume through eductor nozzles is necessary for low-void coverage between wire leads and silver pads. Deposit thickness is 3–5 µm per ASTM B545-13, adhesion is checked by ASTM B571-18 bend or tape method, and solderability is tested per J-STD-002 after 8 h steam aging. Terminal products include SMD power inductors, ferrite bead arrays, and common-mode chokes qualified to AEC-Q200 Rev D for automotive body electronics.
Visible and infrared LED lead frames plated in the 3462MC-matched electrolyte require a low-acid matte tin bath because silver spot-plated die attach areas are not fully masked; aggressive MSA concentrations redissolve the silver and cause die-bond voiding. The electrolyte is held at Sn2+ 12–18 g/L, methanesulfonic acid 90–120 mL/L, wetting agent 1–3 mL/L, with additive replenishment at 0.1–0.3 L per 1000 Ah after initial bath passivation. Barrel plating of 3 mm and 5 mm lamp lead frames proceeds at cathode current density 0.1–0.5 A/dm2, temperature 20–25 °C, rotation 3–6 rpm, and fill volume 20–30% to avoid bent leads and shadowing in deep barrel loads. Minimum tin thickness on the solderable lead section is 1.5–3.0 µm, evaluated by ASTM B545-13; solderability after preconditioning is checked by JESD22-A102 with a 245 °C solder dip, and whisker growth by JESD22-A121 under room temperature storage for 1000 h. Terminal products include through-hole LED lamps, infrared emitters, and optocoupler leadframes used in industrial sensing modules.
Hermetic transistor headers and crystal oscillator bases are plated with nickel and then matte tin to provide a solderable finish without introducing stress that could crack the glass seal. The 3462MC-matched barrel process for these packages uses a sulfamate nickel strike of 1–2 µm, followed by tin from an electrolyte containing Sn2+ 20–28 g/L, methanesulfonic acid 140–170 mL/L, wetting agent 2–4 mL/L, and additive replenishment at 0.3–0.5 L per 1000 Ah. Plating temperature is 25–28 °C, cathode current density 0.5–1.0 A/dm2, barrel rotation 4–8 rpm, and fill volume 15–25% because Kovar leads are dense and can strike against each other during barrel rotation. The tin deposit is specified at 3.8–7.6 µm average thickness on leads, per ASTM B545-13 service condition 2, with solderability tested by MIL-STD-883 Method 2003.7 using 245 °C solder after 8 h steam aging. Whisker control is verified by IEC 60068-2-82 Test Tx at 55 °C/85% RH. Terminal products include TO-46 headers, TO-5 transistor bases, and glass-sealed crystal oscillator platforms for aerospace telemetry circuits.
| Standard/test | Condition or parameter | Application relevance |
|---|---|---|
| ASTM B545-13 | Service condition 2 minimum average 2.5 µm; service condition 1 1.3–1.5 µm | Leaded components, connector pins, chip terminations |
| J-STD-002 | Steam aging 8 h; solder dip 245 °C | SMD terminations, leads, contact springs |
| IEC 60068-2-82 | Test Tx; 55 °C/85% RH, 4000 h | Whisker propensity on matte tin deposits |
| JESD22-A121 | Room temperature storage, 1000 h | Tin whisker growth on leadframes |
| AEC-Q200 Rev D | Passive component qualification | MLCC and inductor terminations |
| SAE/USCAR-2 | Terminal finish durability | Automotive connector terminals |
| MIL-STD-883 Method 2003.7 | Solderability dip 245 °C | Hermetic package leads |
| ASTM B571-18 | Bend and tape adhesion method | Ductility and adhesion verification |
Signal relay contact springs and stamped copper-alloy switch terminals are plated in high-impact barrels where low foam generation is a production requirement; excessive foam from wetting agents causes solution carry-out and inconsistent cathode contact. The 3462MC-matched electrolyte in this segment is maintained at Sn2+ 15–22 g/L, methanesulfonic acid 100–140 mL/L, wetting agent 2–5 mL/L, and additive replenishment at 0.3–0.6 L per 1000 Ah, with continuous filtration through 5 µm polypropylene cartridges to remove particulate generated by mechanical abrasion. Plating parameters are cathode current density 0.4–1.2 A/dm2, temperature 25–30 °C, barrel rotation 10–14 rpm, and fill ratio 30–45% to maximize throughput while avoiding edge build-up on flat springs. Deposit thickness is 1.3–2.5 µm on contact springs where crimp formability is required and 2.5–5.0 µm on solder tails, verified by ASTM B545-13 service conditions 1 and 2 respectively. Solderability is tested by J-STD-002 after 8 h steam aging; ductility is confirmed by ASTM B571-18 bend adhesion test. Terminal products include signal relay contact springs, rocker switch terminals, and printed-circuit-board test point pins.
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In barrel matte tin electrodeposition for electronic connectors, terminal pins, and semiconductor lead frames, the replenishment additive package is the principal control point for deposit morphology, throwing power, and oxidation by-product accumulation. The product designated as Guanghua Technology 3462MC Barrel Matte Tin Additive Matching Solution, Electronic/EL Grade, is an acidic aqueous concentrate intended for use with a paired make-up additive in methanesulfonic acid-based tin electrolytes. Its function is not to supply the tin source but to restore organic grain refiners, antioxidants, and wetting agents lost through drag-out, electrochemical decomposition, and air oxidation during barrel rotation. The EL-grade designation imposes tighter controls on transition-metal contamination, chloride, sulfate, and insoluble particulates than general-purpose technical-grade additives, though exact lot-specific ceilings must be taken from the supplier certificate of analysis. Published data for this specific formulation is limited beyond the manufacturer’s specification; procurement specifications should therefore require lot-specific trace-metal reporting by ICP-MS or ICP-OES and should reject material with unlisted metallic impurity excursions.
Barrel plating consumes organic additives through mechanisms that are less pronounced in rack operations. The tumbling of parts inside polypropylene barrels with perforations typically in the range of 2–5 mm creates alternating solution-air contact, which accelerates aerial oxidation of stannous tin to stannic tin and increases the oxidative degradation of antioxidant components. In addition, the current density across the load is nonuniform; contact areas near the barrel dangler and perforation-rich side receive higher local current densities, while recessed areas and blind holes receive lower local current densities. The matching solution therefore contains components that suppress gas bubble entrapment, refine grain structure in low current density zones, and passivate colloidal stannic acid particles. On multi-barrel automatic lines with barrel volumes from 30 L to 800 L, additive consumption per ampere-hour is affected by drag-out volume, parts geometry, loading density, and barrel open-area ratio. Maintenance programs typically establish replenishment rates in millilitres of additive per ampere-hour as determined by Hull cell panels and production lot solderability results.
The present additive is not a standalone plating bath. It is formulated as a matching replenisher for a specific make-up additive package and is balanced for barrel-specific mass transport. In contrast, rack-only bright tin additives often contain higher concentrations of carrier and brightener species that produce levelled deposits but can yield excessive organic incorporation in barrels. The 3462MC matching solution is adjusted to produce a matte, fine-grained deposit with reduced organic codeposition, which is a relevant distinction for electronic components that undergo thermal aging and solder wetting tests.
| Parameter | Typical MSA-based barrel matte tin system using matched additive pair | Conventional sulfate-based matte tin bath | Analytical or control method |
|---|---|---|---|
| Stannous tin concentration | 15–25 g/L | 25–35 g/L | Iodometric titration with potassium iodate |
| Free acid concentration | 150–200 g/L as methanesulfonic acid | 180–220 g/L as sulfuric acid | Acid–base titration with sodium hydroxide |
| Bath temperature | 20–30 °C | 15–25 °C | PTFE-jacketed immersion heater or external heat exchanger with PID control |
| Cathode current density in barrel | 0.05–0.40 A/dm² | 0.10–0.50 A/dm² | Rectifier current integration divided by total plated area; Hull cell verification at 267 mL |
| Filtration rate | 2–4 turnovers per hour with 1–5 µm polypropylene cartridge | 1–3 turnovers per hour | Flow meter and pressure differential across filter housing |
| Bath pH | below 1.0 | below 1.0 | pH meter with acid-resistant glass electrode |
The ranges in the table represent general operating envelopes common to methanesulfonic acid-based and sulfate-based barrel tin chemistries; lot-specific limits for the Guanghua Technology 3462MC matching solution must be obtained from the supplier. The EL-grade product is typically handled as a low-viscosity liquid with a density close to 1.05–1.15 g/cm³ at 20 °C and a strongly acidic pH. Storage requires sealed containers away from oxidising agents and direct sunlight, with controlled room temperature below 30 °C. Freezing should be avoided because phase separation of the organic components can occur.
The principal difference of the 3462MC barrel matte tin additive system relative to bright tin is the deliberate absence of strong brightener species that create highly levelled reflective deposits. In electronic applications, matte tin deposits are often selected because they contain less incorporated organic material and exhibit lower interfacial stress after thermal cycling. However, matte tin has lower visual uniformity than bright tin, which can complicate automated optical inspection. The EL-grade matching solution is intended to produce a uniformly matte, fine-grained finish without the voiding and gas-pitting defects that arise from additive imbalance in high-speed barrel motion.
Compared with conventional sulfate-based matte tin electrolytes, methanesulfonic acid-based systems offer higher solubility, improved anode dissolution behaviour, and reduced sludge formation. In barrel plating, this translates into less frequent anode bag clogging and lower maintenance of titanium baskets. The 3462MC matching solution is specifically balanced for this methanesulfonic acid matrix; substitution into a sulfate bath without reformulation is not recommended because the wetting and grain-refining components may not remain stable in sulfate media. Conversely, sulfate-based additives transferred to an MSA bath can produce excessive foam, poor low current density coverage, and rapid oxidation of stannous tin.
| Standard or test method | Metric assessed | Typical acceptance criterion for electronic-grade matte tin finish | Equipment or procedure |
|---|---|---|---|
| ASTM B545-13 | Thickness and purity of electrodeposited tin coatings | Minimum local thickness specified by component drawing; commonly 2.5–10 µm for connector leads | Coulometric thickness tester conforming to ISO 2177:2003 |
| IPC/J-STD-002E | Solderability after steam aging | At least 95% of test areas wetted after 8 h steam aging when specified | Solder bath with Pb-free Sn-Cu or Sn-Ag-Cu alloy at 245–260 °C |
| JESD22-A121A | Tin whisker propensity | No whisker exceeding acceptance length; component-specific requirement, commonly 50 µm after 4000 h ambient storage or thermal cycling | SEM or optical microscopy at 100× to 200× |
| RoHS Directive 2011/65/EU | Restricted substance content | Lead below 1000 ppm in homogeneous material unless exemption applies | XRF screening followed by ICP-OES for borderline results |
The compliance matrix identifies test methods used to evaluate finished deposits rather than the additive concentrate itself. For the EL-grade chemical, the supplier specification should include metal impurity reporting, visual appearance, and density. In-line process control is commonly performed by potentiometric titration for stannous tin and free acid, while Hull cell testing at 267 mL and 1 A for 5 min provides a qualitative check of additive balance. Cyclic voltammetric stripping may be used on automated lines to maintain organic additive concentration, but published calibration data for this specific 3462MC matching solution is limited.
In a fixed barrel cathode, the parts near the barrel wall experience mechanically induced solution exchange during rotation, while parts in the centre of the load remain partially diffusion-limited. This creates a distribution of local current density that can range from less than 0.01 A/dm² in shielded blind holes to more than 0.50 A/dm² at exposed high-point edges. A barrel-specific tin additive package must produce acceptable deposits across this range without forming spongy tin at low current density or burnt tin at high current density. The 3462MC matching solution is formulated to be added in proportion to current passed, so that the low current density coverage and high current density tolerance remain balanced as the bath ages.
Production-scale experience on barrel lines with load densities between 0.2 kg/L and 1.0 kg/L of barrel volume indicates that dragged-in moisture and acidic pre-dip carryover can alter the additive balance by locally diluting the bath or raising chloride contamination. Chloride ingress above accepted limits for MSA tin electrolytes can attack copper substrates and reduce solderability after aging. The use of dedicated barrels, racks, and filtration equipment is therefore required. Cross-contamination from bright nickel or copper pyrophosphate lines should be prevented through segregated hoods and separate rinse systems, because even low concentrations of metallic and organic contaminants can disturb the grain-refinement behaviour of the matching solution.
Anode selection also affects solution stability. The preferred anode material is high-purity tin, minimum 99.9%, placed in titanium baskets with polypropylene anode bags. If anode bags become fouled with stannic oxide sludge, anode polarisation increases and free acid consumption may rise. Premature sludge formation in MSA tin baths is typically caused by high temperature, excessive air agitation, or the presence of iron and copper impurities. Baths using the 3462MC matching solution should be maintained below 30 °C and filtered continuously. Air agitation should be replaced with mechanical barrel rotation and eductor-driven solution movement where possible, because air agitation accelerates stannous oxidation and additive consumption.
Lot-to-lot variation in raw electronic-grade tin salts can shift the additive response even when the matching solution remains unchanged. Purchasing records should therefore associate each bath make-up with the tin salt lot number and the additive lot number, permitting traceability if deposit roughness or solderability deviations occur. Routine bath analysis after make-up and after each 10,000 A·h of production throughput is a practical monitoring interval, but high-speed barrel lines processing small parts may require more frequent sampling when the drag-out volume exceeds 0.5 L per load. The replenishment rate of the matching solution cannot be fixed without ampere-hour integration and visual or instrumental deposit checks, because parts geometry and barrel loading dominate consumption rate.
Operational boundaries include avoidance of oxidising agents such as hydrogen peroxide or peroxymonosulfuric acid in the rinse water entering the plating bath. These agents oxidise stannous tin to stannic tin and can precipitate the organic grain refiner. Similarly, the matching solution should not be mixed with amine-based brightener packages, which can cause phase separation or excessive foaming in the strongly acidic methanesulfonic acid matrix. The EL-grade classification does not exempt the material from standard hazardous chemical handling protocols; the acid concentrate must be stored in acid-resistant containers, and transfer lines should be constructed of polypropylene, PVDF, or PTFE. If the bath is left idle for more than 72 h, the stannous tin concentration should be rechecked and the bath may require a maintenance addition of antioxidant component before production resumes.
