| HS Code | 311555 |
| Product Series | SuA-2, TaA-2 |
| Appearance | Silver-gray viscous paste |
| Silver Content | 70-80 wt% |
| Solids Content | 78-85 wt% |
| Viscosity | 20,000-40,000 mPa·s at 25°C |
| Thixotropic Index | 1.5-2.5 |
| Curing Condition | 150°C for 30 minutes in air |
| Cured Film Resistivity | Less than 1.0 x 10^-4 Ω·cm |
| Adhesion Strength | Greater than 1.5 kg/mm² on ceramic substrate |
| Pencil Hardness | 3H minimum |
| Storage Temperature | 5-10°C |
| Shelf Life | 6 months in sealed container |
As an accredited Conductive Silver Paste SuA-2, TaA-2 Series factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Conductive Silver Paste SuA-2, TaA-2 Series is supplied in sealed containers, typically 100 g per jar, ensuring safe storage. |
| Container Loading (20′ FCL) | One 20′ FCL containing Conductive Silver Paste SuA-2, TaA-2 Series, safely packed on pallets, ready for export shipment. |
| Shipping | Conductive Silver Paste SuA-2, TaA-2 Series ships as a hazardous material requiring UN-compliant packaging, leak-proof containers, and flammable-solvent labeling. Transport dry, upright, away from heat, sparks, and moisture. Follow local/international dangerous goods regulations; ensure proper documentation and handling to prevent leakage or skin contact. |
| Storage | Store Conductive Silver Paste SuA-2/TaA-2 in original, tightly sealed containers in a cool, dry, well-ventilated area. Avoid direct sunlight, high temperatures, and humidity. Recommended storage: 5–25°C. Keep away from flames, sparks, and incompatible materials. Ensure containers remain sealed when not in use to prevent solvent evaporation and contamination. |
| Shelf Life | Shelf life is 6 months from production date when stored unopened at 2–10°C, sealed tightly, away from light. |
On crystalline silicon heterojunction cell lines, front-side silver metallization is deposited after transparent conductive oxide sputtering and before module lamination. The amorphous silicon passivation stack imposes a hard thermal ceiling of 220 °C; exposure above this threshold for more than 10 min degrades implied open-circuit voltage through hydrogen effusion and p-layer doping loss. Conductive Silver Paste SuA-2 is therefore processed in a six-zone belt furnace with infrared and forced convection zones, peak zone set point 200 °C, and belt speed adjusted to deliver 18 min above 180 °C after solvent evacuation. The screen specification for front fingers is typically 360/16 stainless-steel wire with calendered emulsion thickness of 10 µm to 12 µm over mesh; snap-off is held at 1.0 mm to 1.2 mm, and squeegee stroke speed is 100 mm/s to 150 mm/s using a diamond-shaped squeegee at 70 Shore A. Paste viscosity under print shear is measured on a Brookfield HBDV-II+ Pro at 10 rpm with spindle SC4-14; values below 20 Pa·s produce finger widening, while values above 50 Pa·s cause mesh clogging and skipped fingers. Wet film thickness of 20 µm to 25 µm is verified with a non-contact laser displacement sensor before cure. After drying, four-point probe sheet resistance mapping according to ASTM F390-11 is used for electrical acceptance. Typical dried-film volume resistivity for low-temperature silver pastes of this class falls between 4 × 10-5 Ω·cm and 9 × 10-5 Ω·cm; published data for SuA-2 on random-pyramid textured indium tin oxide is limited and requires lot-specific confirmation on the target texture. Adhesion to the transparent conductive oxide is assessed by crosshatch tape peel according to ASTM D3359-17, with acceptance class 4B or better before lamination. End modules are qualified under IEC 61215-2:2021, including thermal cycling test MQT 11 and humidity-freeze test MQT 12; the metallization must retain less than 5% line conductivity degradation after 200 cycles between −40 °C and +85 °C. RoHS compliance for the final module is verified by supplier declaration and IEC 62321 screening methods.
For flexible printed electrodes on heat-stabilized polyethylene terephthalate or polycarbonate, the curing window is set by substrate dimensional stability rather than by the silver paste chemistry. TaA-2 series is evaluated on heat-stabilized PET with machine-direction shrinkage of 0.1% at 150 °C after 30 min; the cure profile is therefore limited to 130 °C to 145 °C for 20 min in a forced-air oven with cross-flow uniformity of ±2 °C. Substrate pre-drying at 60 °C for 4 h is required when ambient relative humidity exceeds 60%, because trapped moisture at the paste-substrate interface causes bubble defects during solvent evaporation. The screen is polyester 300/27 or stainless 325/23 with emulsion over mesh of 8 µm to 10 µm; this produces cured line width of 90 µm to 120 µm from a nominal 75 µm screen opening. Minimum line spacing under production conditions is 150 µm, because edge waviness typically consumes ±20 µm per edge. The dry silver content in this application class usually falls between 80 wt% and 90 wt%, which determines the trade-off between volume resistivity and film elongation. Dilution with retarder thinner above 2 wt% lowers press-ready viscosity below the printable window and increases bleed on polycarbonate; rheometer verification per ISO 3219:1994 is required before any such adjustment. Adhesion is tested by tape peel according to ASTM D3359-17; on polycarbonate, silane priming can raise the result from class 3B to class 5B. The dried traces are then overcoated with UV-curable dielectric if the end product is a wearable ECG electrode array. Without overcoat, silver migration across adjacent traces under 5 V DC bias and 85% RH becomes measurable within 168 h in accelerated tests. Biocompatibility for medical wearable electrodes is a final-device requirement evaluated according to ISO 10993-5:2009 for cytotoxicity and ISO 10993-10:2021 for skin sensitization; the paste itself is not certified as medical grade. RoHS limits for lead, mercury, cadmium, and hexavalent chromium are verified by IEC 62321-4 and IEC 62321-5 with detection limits below 0.01 wt%. End products include single-use wearable biosensor patches and flexible membrane keyboard circuits.
Because the two series are often compared on the same production line when a product family spans both rigid and flexible substrates, the following table consolidates typical process windows. The values are not datasheet specifications; they represent commonly observed ranges for low-temperature silver paste classes and must be verified on the target line.
| Parameter | SuA-2 series | TaA-2 series | Test method |
|---|---|---|---|
| Peak cure temperature | 180–200 °C | 120–145 °C | Thermocouple in film plane |
| Minimum dwell above cure threshold | 15–20 min | 8–15 min | Belt speed profiling |
| Viscosity at 10 s⁻¹ | 35–50 Pa·s | 25–45 Pa·s | ISO 3219:1994 |
| Screen mesh | 360/16 | 300/27–380/14 | Wire count per inch |
| Adhesion class after cure | 4B–5B | 3B–5B without primer | ASTM D3359-17 |
Near-field communication and UHF RFID antenna coils printed on coated paper require a low drying burden because paper loses dimensional stability above 110 °C and may yellow at 120 °C. TaA-2 is preferred in this application because its lower curing temperature reduces paper cockle; SuA-2 can be used when higher conductivity per unit thickness is demanded and the paper grade tolerates 150 °C after coating. The paste is applied by flatbed or rotary screen with a 380/14 stainless mesh and emulsion thickness of 8 µm; a butt-step squeegee geometry reduces paste scooping on high-roughness paper surfaces. Viscosity is profiled on a Haake Mars 40 rheometer with a 35 mm parallel plate at 23 °C; values at 1 s⁻¹ should fall between 80 Pa·s and 120 Pa·s, while equilibrium viscosity at 100 s⁻¹ falls to 15 Pa·s to 30 Pa·s to allow mesh release without slumping. Cure is conducted with near-infrared panels and forced air at 105 °C for 10 min to 15 min, yielding dry-film sheet resistivity suitable for UHF dipole antennas. The printed antenna is measured with a vector network analyzer; return loss at 860 MHz to 960 MHz should remain above 10 dB after 40 min at 50 °C and 95% RH if an overcoat is applied. Without overcoat, silver electromigration and cellulose swelling degrade throw distance irreversibly. Compliance for NFC tags references ISO/IEC 14443-2 for proximity coupling and ISO/IEC 18000-63 for UHF passive tags; the conductive paste itself is not certified, but its use must not reduce read range below the chip sensitivity threshold. End products include RFID inventory labels, transit fare tokens, and printed sensor antennas.
In printed electroluminescent lamp construction, silver paste serves as the rear electrode and busbar collector, while the front electrode is usually indium tin oxide-coated polyester. The rear silver layer is applied over a printed dielectric and phosphor stack, so TaA-2 must not redissolve or plasticize the underlying UV-cured or solvent-cast dielectric. A rear electrode print is made with 230/31 stainless mesh and an emulsion thickness of 18 µm, producing a dry film thickness of 25 µm to 30 µm after cure at 120 °C for 10 min. Solvent entrapment is a known production failure; forced-air exhaust of 2 m³/min per meter of oven width is recommended, with peak solvent concentration in the drying tunnel maintained below 20% lower explosive limit. The resulting busbar resistance is tested by four-terminal Kelvin measurement; an increase above 15% after 1000 h at 60 °C and 90% RH indicates incomplete drying or inadequate overcoat. In membrane switch tail frames, the same paste is used for crossing traces and connector pad build-up. Pad edge cracking occurs when silver film elongation does not match the polycarbonate tail flexing radius of 2 mm; tape peel adhesion per ASTM D3359-17 should remain class 4B after 5000 dynamic flex cycles at 2 mm radius. End products include electroluminescent backlight panels for membrane switches and automotive climate-control interface tails.
For bonded strain sensors and force-sensing resistor arrays on polyimide substrates, SuA-2 traces operate below their fatigue threshold when cured thoroughly at 180 °C for 30 min, but undercure leaves organic residues that raise contact resistance and drift under cyclic loading. A polyimide substrate with glass transition above 300 °C allows higher curing; however the conductive film must not exceed 20 µm dry thickness because thicker deposits develop shrinkage cracks at 2.5% tensile strain. The screen is 325/23 stainless steel with an emulsion thickness of 10 µm; print-flood-print sequencing is required to eliminate voids in the gauge grid. After cure, gauge resistance is trimmed by laser ablation to ±0.5% of nominal. Gauge factor is validated by four-point bending according to ASTM E251-92; drift beyond 0.2% over 1000 h at 85 °C is rejected. Incompatibility exists with tin-lead rosin fluxes, as residual carboxylic acids cause silver sulfide or silver chloride growth at soldered terminations; no-clean solder paste with halide content below 500 ppm according to J-STD-004B is required. End products include pressure-mapping insoles and robotic gripper tactile arrays.
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Conductive Silver Paste SuA-2, TaA-2 Series is supplied as a two-family silver thick-film metallization system for screen printing, stencil printing, and pneumatic or volumetric dispensing. SuA-2 is formulated for low-temperature cure on polyester, polyimide, and indium tin oxide-coated glass, while TaA-2 is formulated for high-temperature sintering on alumina, barium titanate, and other oxide ceramic bodies. Both families use a mixed silver flake/spherical filler population; the organic vehicle in SuA-2 is a hybrid thermoplastic/thermosetting resin system, and TaA-2 contains an inorganic glass frit package for ceramic adhesion. The model suffix denotes solids fraction, solvent vapour pressure, and particle-size class, so the two series are not interchangeable across print platforms. A lot-specific certificate of analysis supplies release values for silver content, fineness of grind, viscosity, and water content.
On automated flatbed lines with a 400 mm × 400 mm print bed, batch-to-batch solvent loss during open-screen operation is measured by weight loss rather than elapsed time. Three-roll milling on a 200 mm roll diameter mill with a 5 µm gap can shift viscosity by ±10 % if the paste temperature exceeds 45 °C; cooling water below 20 °C is therefore used. The product family is inspected on arrival with a cone/plate viscometer at 25 °C and a laser diffraction particle-size analyser per ISO 13320. This incoming inspection detects coarse agglomerates that do not appear on a Hegman gauge alone.
Rotational viscosity measured at 25 °C and 10 s−1 under ISO 3219 is the primary incoming-control parameter. SuA-2 lots typically fall between 8 Pa·s and 35 Pa·s, while TaA-2 lots are higher, between 25 Pa·s and 80 Pa·s. The thixotropic index, calculated as the ratio of apparent viscosity at 1 s−1 to 10 s−1, is kept below 2.0 for SuA-2 to support fine-line leveling and above 4.0 for TaA-2 to maintain edge geometry on vertical ceramic surfaces. Silver content by thermogravimetric analysis under ASTM E1131 is 55 wt% to 75 wt% for SuA-2 and 75 wt% to 88 wt% for TaA-2. The higher silver loading in TaA-2 is necessary to reduce sintered film porosity when the glass frit wets the ceramic grain boundaries, but it also raises the yield stress and requires lower print speeds.
| Parameter | SuA-2 | TaA-2 | Method |
|---|---|---|---|
| Viscosity at 25 °C, 10 s−1 | 8 Pa·s to 35 Pa·s | 25 Pa·s to 80 Pa·s | ISO 3219 |
| Thixotropic index | 1.2 to 2.0 | 4.0 to 6.5 | ISO 3219 |
| Silver content | 55 wt% to 75 wt% | 75 wt% to 88 wt% | ASTM E1131 |
| Particle size D50 | 2 µm to 6 µm | 1 µm to 4 µm | ISO 13320 |
| Peak process temperature | 80 °C to 180 °C | 550 °C to 850 °C | Profile furnace |
| Volume resistivity | 1.5 × 10−5 Ω·cm to 5.0 × 10−5 Ω·cm | 2.0 × 10−6 Ω·cm to 8.0 × 10−6 Ω·cm | ASTM D257 / four-point probe |
| Adhesion after cure or fire | 5B on polyimide | 4B on 96 % alumina | ISO 2409 |
Screen printing is performed through stainless-steel mesh counts of 325 to 500 threads per inch with emulsion thicknesses of 10 µm to 25 µm. The resulting wet film thickness ranges between 8 µm and 35 µm depending on squeegee durometer, snap-off distance, and mesh tension. SuA-2 reaches tack-free drying within 10 min to 20 min at 120 °C in a forced-air tunnel; TaA-2 requires a staged organic burnout plateau at 350 °C to 450 °C before peak sintering. On open screens, solvent evaporation raises paste viscosity by 15 % to 25 % per hour; approved thinners should not exceed 2 wt% of original paste mass because silver content and sheet resistance shift outside the specified range.
Fine-line resolution below 100 µm is limited primarily by the coarse flake tail rather than by the median particle size. A 400 mesh with 25 µm wire diameter has an aperture near 38 µm; a silver flake with a major axis exceeding 15 µm can bridge the aperture and generate starved line segments. SuA-2 grades with a D90 below 8 µm are suited to 80 µm line arrays, while TaA-2 grades with a D90 below 6 µm are used for ceramic termination lines at 60 µm. Print speed, squeegee pressure, and screen tension interact through the paste yield stress: a yield stress above 200 Pa can reduce mesh release and produce dog-bone profiles when emulsion thickness exceeds 20 µm. TaA-2 compensates with a higher thixotropic index, but this also means that insufficient squeegee speed can leave transverse ripple marks in the wet film.
TaA-2 replaces conventional 85/15 Ag/Pd termination paste in multilayer ceramic capacitor and chip inductor termination where pure silver metallization is permitted by the subsequent plating process. Unlike 85/15 Ag/Pd systems, TaA-2 does not rely on palladium to inhibit silver migration; it uses a glass frit package that densifies in the 650 °C to 850 °C window and bonds to the ceramic surface. The substitution narrows the firing tolerance: peak temperature should remain below 900 °C to avoid excessive silver penetration into barium titanate, and the air-to-nitrogen transition must occur after organic burnout is complete. Compared with carbon-based conductive inks, SuA-2 provides lower cured film resistivity, but its silver flake network is susceptible to contact-resistance drift when exposed to amine-curing epoxies. Compared with low-solids silver paints used for repair, both SuA-2 and TaA-2 are formulated for stencil release and repeatable wet-film thickness rather than brush application.
Pneumatic dispensing of SuA-2 through a 22 to 27 gauge needle is permitted after thinning to 10 Pa·s to 15 Pa·s at 10 s−1; TaA-2 is not recommended for time-pressure needle dispensing because its high yield stress causes tailing and stringing. In stencil printing, a 0.10 mm laser-cut electroformed stencil supports pad arrays down to 150 µm. Paste slump after deposition is controlled by maintaining TaA-2 thixotropic index above 5.0; lower values may produce encroachment between adjacent pads on vertical ceramic side faces. A solderability test under IEC 60068-2-58 is used for process qualification after cure or firing. TaA-2 fired above 650 °C can survive passive solder dip, while SuA-2 requires a pre-tinning step before wave soldering.
| Requirement | Limits or method |
|---|---|
| RoHS Directive 2011/65/EU amended by (EU) 2015/863 | Pb < 1000 ppm, Cd < 100 ppm, Hg < 1000 ppm, hexavalent chromium < 1000 ppm, PBB/PBDE < 1000 ppm; screening by IEC 62321-5 |
| REACH Regulation EC 1907/2006 | Candidate list SVHC < 0.1 wt% per article; lot certificate |
| Halogen content | Cl < 900 ppm, Br < 900 ppm, total < 1500 ppm; EN 14582 |
| Storage | 5 °C to 25 °C, RH < 60 %; sealed container |
Frozen storage is not recommended; paste subjected to freezing can phase-separate because the solvent package has limited low-temperature solubility. If a container has been exposed to temperatures below 0 °C, the paste should be quarantined and inspected for syneresis before use. Pre-drying of substrates is required when ambient relative humidity exceeds 60 %; residual moisture on alumina or polyimide can generate pinholes and reduce film adhesion during transfer. The pastes are incompatible with amine-based curing agents used in certain overcoat epoxies; amine exposure can increase cured film resistivity and weaken the silver–epoxy bondline. SuA-2 should not be exposed to ketone-based cleaning solvents before full cure because the organic vehicle can soften and release silver flake. Published independent failure-rate data for the specific SuA-2/TaA-2 configuration is limited; lot-specific certificates and process validation should therefore define acceptance limits rather than historical field data.
