| HS Code | 719939 |
| Thermal Conductivity | 25 W/m·K |
| Volume Resistivity | ≤ 1.0 × 10⁻⁴ Ω·cm |
| Viscosity | 55,000 ± 10,000 mPa·s |
| Silver Content | 80 ± 2 wt% |
| Particle Size D90 | ≤ 8 μm |
| Low Temperature Cure Range | 90–150 °C |
| Curing Time | 20–40 minutes |
| Adhesion Strength | ≥ 2.0 kN/cm² |
| Specific Gravity | 2.8 ± 0.2 |
| Coefficient Of Thermal Expansion | 3.5 × 10⁻⁵ /°C |
| Refrigerated Shelf Life | 6 months at 2–10 °C |
| Storage Temperature | 2–10 °C |
As an accredited High Thermal Conductive Low-temperature Conductive Silver Paste Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged as 100 g in a sealed, light-resistant container, ensuring safe delivery of high thermal conductive, low-temperature silver paste for electronic/EL applications. |
| Container Loading (20′ FCL) | A 20′ FCL securely loads drums/cartridges of high thermal conductive silver paste, preventing damage and contamination for safe transit. |
| Shipping | This product ships in sealed, leak-proof containers with proper hazardous-material labeling. It is transported via ground freight only, as it may contain volatile solvents. Keep away from heat, sparks, and open flames during transit. Ensure compatibility with carrier regulations for electronic-grade silver paste before dispatch. |
| Storage | Store in the original tightly sealed container in a cool, dry, well-ventilated area, ideally refrigerated at 2–10°C. Keep away from sunlight, heat, sparks, and moisture. Before use, allow the paste to reach room temperature to prevent condensation. Follow the manufacturer’s shelf-life guidelines. |
| Shelf Life | Store in cool, dark, sealed conditions; typical shelf life is 6–12 months before performance degrades. |
On a 50 µm annealed polyimide web, the silver flake-loaded thermoset paste is printed through a 250-mesh stainless-steel screen with 10–15 µm emulsion over-screen build. This establishes conductive traces that survive downstream flex, gap-press lamination, and connector insertion. The paste is normally used as a single-component system; silver flake loading falls between 78 wt% and 83 wt%, with solvent at 5–10 wt% and reactive diluent at 2–5 wt%. Mixing before application is performed at 400–800 rpm for 3–5 min under -80 kPa vacuum. Wooden spatulas are incompatible because they introduce moisture and particulate contamination. On production sheets, wet-film thickness is controlled to 14–18 µm; cure is run in a three-zone forced-air tunnel at 120–140 °C for 10–20 min for polyimide, while 125 µm PET circuits are restricted to 90–100 °C for 15–20 min. The governing standard for flexible printed-board quality is IPC-6013, with acceptance criteria referenced to IPC-A-600. Electrical acceptance is measured by ASTM D257-14; cured traces should exhibit volume resistivity no greater than 1×10⁻⁴ Ω·cm at 25 °C. Adhesion is evaluated by ASTM D3359-23 Method B; a minimum of 3B is typical for PET and 4B for polyimide. Thermal conductivity after cure lies typically in the 2.0–3.5 W/(m·K) range when measured by ASTM E1461-13. When relative humidity exceeds 60%, both polyimide and PET webs must be pre-dried at 80 °C for 45–60 min before printing. Amine-functionalised adhesion promoters degrade pot life below 4 h at 23 °C and cause viscosity climb during long screen runs; such additives are generally avoided in epoxy-bearing silver grades. The finished traces serve flexible printed circuits, sensor electrode tails, and printed foil connectors.
In membrane-switch and human-machine-interface circuits printed on 125 µm polycarbonate or PET, the principal failure mode is micro-cracking of the silver flake network, not cohesive rupture of the binder. To limit this risk, silver loading is adjusted to 70–75 wt%, and fumed silica is added at 0.5–1.0 wt% to prevent settling without excessive low-shear viscosity. Screen selection is normally 250–305 mesh with 8–12 µm emulsion thickness; dry-film thickness is held at 18–25 µm for tactile switch tails. The paste is printed at a squeegee durometer of 75 Shore A, snap-off 1.0–1.8 mm, and platen speed 30–80 mm/s. After printing, the wet trace is allowed to level for 5–10 min at room temperature; early tunnel entry causes solvent pop. Curing is carried out at 90–100 °C for 8–12 min in a forced-air oven. Adhesion is verified by ASTM D3359-23 Method B; a minimum of 4B is expected on polycarbonate. Mandrel bend flexibility is assessed by ASTM D522-17; the trace should withstand a 2.0 mm radius without line resistance increasing more than 20%. Electrical resistance is tested under ASTM D257-14, and printed sheets are aged for 48 h at 85 °C and 85% RH before lot release. Cyclic flex data from production lots show that resistance rise accelerates after 100 000 cycles when the dry-film thickness exceeds 30 µm, because thick silver flake layers build internal stress at the resin interface. The final traces are die-cut, laminated into tactile keyboards, and terminated with carbon overprint at connector tails to resist silver migration. A cyclohexanone-free retarder is added at 2–4 vol% when screen open time exceeds 2 h; higher additions reduce cure density and increase tape-snap failure. These traces find terminal use in membrane keyboards, appliance control panels, and industrial keypads.
The rear electrode of an electroluminescent lamp is normally deposited onto a cured barium titanate-loaded dielectric layer after the phosphor and dielectric have been printed and dried. This layer forms the low-side conductive plane of the lamp and must accept high-frequency AC drive without hot-spot formation. The paste is specified with silver flake loading of 80–85 wt%; viscosity at 25 °C is held between 20 000 cP and 35 000 cP at 10 s⁻¹ to match flatbed screen equipment. Screen mesh is 200–250 mesh; the wet print is deposited at 25–35 µm, yielding a dry rear electrode after cure. The critical processing boundary exists because the laminated PET/ITO substrate begins to shrink when cure exceeds 100 °C. The production cure window is therefore 95 °C ±5 °C for 10–15 min; excursions above 105 °C cause visible substrate curl, and temperatures below 90 °C leave residual solvent that later attacks the dielectric, creating dark spots in the lit lamp. Dry adhesion to the dielectric is tested by ASTM D3359-23 Method B; 2B–3B is recorded on release-coated high-k dielectric surfaces. Volume resistivity is evaluated by ASTM D257-14 after cure; values in the 1×10⁻⁴ Ω·cm range are targeted. Thermal conductivity of the cured electrode measured per ASTM E1461-13 commonly falls between 0.8 W/(m·K) and 1.5 W/(m·K) on the dielectric interface, lower than on bare PET because of interfacial resistance. The electrode is formulated without sulphur-cured additives because sulphur accelerates silver tarnishing under the alternating field. If foaming appears after mixing, the paste is allowed to stand for 10 min before printing; vacuum de-aeration at -60 kPa is preferred. Terminal products include EL backlights for instrument clusters, wearable safety panels, and decorative signage.
When rotary-screen equipment is configured for 200 mm wide paper webs at 60 m/min, the silver paste is reduced to high-shear viscosity of 800–1 200 cP at 100 s⁻¹. Silver flake loading is set at 75–80 wt%, and the solvent package is adjusted for fast flash-off because dwell time in the hot-air zone is only 2–5 s. Screen mesh is 200–250 mesh; the printed antenna trace has wet-film thickness of 12–18 µm, which yields a dry film in the 8–12 µm range. After drying at 100–120 °C in a tunnel oven, the antenna loop resistance is measured by ASTM D257-14; volume resistivity at or below 1×10⁻⁴ Ω·cm is generally required for UHF read-range stability. The finished inlay is tested against ISO/IEC 18000-6C interrogator interrogation; in production, a 12% increase in loop resistance corresponds to measurable read-range loss because the antenna Q factor shifts away from the chip impedance match. Edge definition is controlled to ±50 µm; blade bleed beyond this value alters the parasitic capacitance between turns. Paper surface acidity is a known operational boundary; sulfate and sulfide residues from recycled board stocks accelerate silver tarnishing after 30 days at 40 °C/90% RH. Papers with a pH below 4.5 are excluded by incoming inspection. The table below summarises the substrate-dependent cure and performance envelope reported in commercial supplier datasheets for this class of low-temperature silver paste.
| Substrate | Typical cure window | Volume resistivity (ASTM D257-14) | Cross-hatch adhesion (ASTM D3359-23) | Cured thermal conductivity (ASTM E1461-13) |
|---|---|---|---|---|
| 125 µm chemically stabilised PET | 90–100 °C, 10–15 min | ≤8×10⁻⁵ Ω·cm | 3B–4B | 1.5–2.8 W/(m·K) |
| 50 µm polyimide | 120–140 °C, 10–20 min | ≤6×10⁻⁵ Ω·cm | 4B–5B | 2.0–3.5 W/(m·K) |
| Barium titanate dielectric over PET | 95 °C ±5 °C, 10–15 min | ≤1×10⁻⁴ Ω·cm | 2B–3B | 0.8–1.5 W/(m·K) |
| 80 g/m² clay-coated paper | 100–120 °C, 2–5 s | ≤1×10⁻⁴ Ω·cm | 2B–3B | 0.5–1.0 W/(m·K) |
Terminal inlays are laminated into wet-inlay or dry-inlay structures for retail, logistics, and pharmaceutical item-level labelling. Published batch data for nitrogen-cured and air-cured variants on uncoated woodfree paper are limited; incoming paste is qualified on the target substrate rather than extrapolated from PET values.
A 325-mesh stainless-steel screen with 10 µm emulsion thickness prints border bus bars at dry-film thickness of 8–15 µm on ITO-coated PET or glass. The replacement of vacuum-deposited or etched aluminium reduces process cost but introduces a cure boundary: ITO-PET is restricted to 100 °C for 15 min, while ITO-glass can be cured at 120–130 °C for 20 min. Silver flake loading is maintained at 80–85 wt%, and fumed silica is added at 0.5–1.5 wt% to hold the paste on the screen. Above 1.5 wt% fumed silica, volume resistivity climbs non-linearly because the thixotrope disrupts flake-to-flake contact; at 2.0 wt%, resistivity is often twice the value obtained at 1.0 wt%. The paste pH is held at 6.5–7.5; acid-modified adhesion promoters below pH 5.0 attack ITO and increase contact resistance at the bus-bar interface. After cure, electrical acceptance is tested by ASTM D257-14; bus-bar resistance is usually specified as less than 5 Ω across a 100 mm length. Adhesion is verified by ASTM D3359-23 Method B on ITO-bearing surfaces; 3B is considered acceptable for PET-based touch sensors. Thermal conductivity of the cured silver layer falls between 2.0 W/(m·K) and 3.2 W/(m·K) as measured by ASTM E1461-13, allowing the bus bar to spread heat away from soldered flex attach points. In production, high-speed dispensing through a 23G needle at 0.3 MPa is used for touch-panel perimeter wiring when the repeat length is below 500 mm; vacuum de-aeration after refill prevents needle clogging from agglomerated silver flakes. Terminal components include projected-capacitive touch sensors, display edge shields, and electronic whiteboard border traces. This segment carries a narrow rheological boundary; if screen open time exceeds 2 h, the addition of 0.5–1.0 vol% glycol ether acetate retarder is preferred over solvent xylene, which leaves residual odour and reduces adhesive bond strength to ITO.
On flat polyester printing lines, CNC dispensing heads pull paste from a 2 kg cartridge through a 0.6 mm needle at 0.3 MPa; wet line width is controlled to ±0.15 mm. The traces become resistive heating elements after lamination into automotive seat heater pads, heated steering wheel pads, or mirror defogger films. The paste is formulated at 78–83 wt% silver flake with a glass transition temperature of the cured binder between -20 °C and 0 °C to survive low-temperature flex during seat installation. Viscosity at 25 °C is held between 18 000 cP and 28 000 cP; screen printing through 200–250 mesh yields dry-film thickness of 20–30 µm. Curing is performed at 90–100 °C for 15–20 min on 125 µm PET; higher temperatures produce dimensional distortion, and lower temperatures leave a tacky binder surface that blocks during roll rewind. The primary electrical parameter is sheet resistance uniformity, measured by ASTM D257-14; a local dry-film thickness increase of 10% lowers local resistance and produces hot spots under constant-voltage operation. Thermal conductivity after cure is measured by ASTM E1461-13 and falls commonly between 2.0 W/(m·K) and 3.0 W/(m·K); this value helps maintain uniform heat distribution when the substrate is bonded to polyurethane foam. Adhesion to PET is checked by ASTM D3359-23; 4B is expected before lamination. Finished seat-heater pads are validated under ISO 16750-4:2016 temperature cycling and must survive 1 000 cycles from -40 °C to 85 °C without resistance drift greater than 10%. The paste must be stored at 5–10 °C and conditioned at 23 °C for 2 h before opening to avoid condensation. Silicone release agents from upstream lamination must be excluded from the print area; silicone contamination below 0.1 µg/cm² is difficult to detect but causes cratering and local insulation gaps. Sulfur-containing foam systems are incompatible because sulfur diffuses into the trace and forms silver sulfide, increasing resistance during service life. Terminal products are heated seat pads, mirror heating films, and battery thermal-management pads for electric vehicles.
Single-use ECG electrodes employ the conductive silver paste as the silver backplane between a carbon or Ag/AgCl contact layer and the snap electrode. The paste is printed on spunbond nonwoven or open-cell foam at 10–15 µm dry-film thickness and cured at 90–110 °C for 15–20 min. Silver flake loading is held at 75–82 wt%, and the solvent system is selected so residual post-cure solvent is below 0.1 wt% as measured by headspace GC, because solvent residues extract into 0.9% w/v NaCl electrolyte and cause local irritation. The binder must maintain adhesion after 24 h saline immersion at 37 °C; adhesion is tested by ASTM D3359-23 before and after immersion, with a maximum acceptable loss of one classification step. Volume resistivity is measured by ASTM D257-14; values above 1×10⁻⁴ Ω·cm are rejected because the electrode impedance rises above product specification. Biocompatibility is assessed according to ISO 10993-5:2009 for cytotoxicity and ISO 10993-10:2010 for skin sensitisation and irritation; the cured conductive film, not the liquid paste, is submitted. A DC bias of 20 µA/cm² applied for 24 h in contact with saline-soaked gauze accelerates delamination at the foam interface and distinguishes undercured lots. Gamma irradiation at 25 kGy may embrittle some vinyl-based binder systems; electron-beam or ethylene oxide sterilisation is generally preferred for these formulations, but published data for this specific paste grade under gamma are limited. Chloride-containing solvents are incompatible because they precipitate ionic silver and shift the half-cell potential at the electrode surface. The paste is also used in iontophoresis pads and disposable biosensor strips where the cured trace must carry low DC currents without generating excessive noise; terminal products include ECG electrodes, TENS contacts, and wearable cardiac monitoring patches.
Competitive High Thermal Conductive Low-temperature Conductive Silver Paste Electronic/EL Grade prices that fit your budget—flexible terms and customized quotes for every order.
For samples, pricing, or more information, please contact us at +8615365186327 or mail to admin@ascent-chem.com.
We will respond to you as soon as possible.
Tel: +8615365186327
Email: admin@ascent-chem.com
Flexible payment, competitive price, premium service - Inquire now!
Designated HTC-LT-240 EL, this single-component, solvent-borne silver flake-filled polymer system is formulated for screen printing rear electrodes, bus bars, and thermal spreading traces on heat-sensitive electroluminescent lamp stacks and flexible printed electronic substrates. The material is supplied in 100 g, 250 g, and 1 kg wide-mouth polypropylene jars with vapour-seal closures at 0–10 °C. It is intended for deposition through 200–325 mesh stainless steel screens or 50–75 µm stencils. The formulation is controlled for low halide content with chloride 50 ppm, sulfur 100 ppm, and sodium 50 ppm to limit ITO corrosion and phosphor poisoning in EL laminates. Cured films exhibit sheet resistance below 15 mΩ/sq/25 µm after 120 °C cure, through-plane thermal conductivity in the 3.2–4.2 W·m⁻¹·K⁻¹ range, and adhesion to ITO-coated PET without delamination after 20,000 flex cycles at 5 mm bend radius when tested to IPC-TM-650 2.4.3.1. The material is designed to meet RoHS recast 2011/65/EU and REACH 1907/2006 lot-level restrictions for the listed SVHCs. The primary operating envelope is defined by the low-temperature cure requirement and the high silver flake loading required for simultaneous electrical and thermal transport.
Low-temperature cure is obtained through a thermoplastic acrylic-modified polyester binder, not through silver sintering. The binder is solvated in diethylene glycol monoethyl ether acetate and dibasic ester solvents with boiling points between 210 °C and 250 °C. During the first drying phase at 80 °C for 10 min, approximately 75% of the solvent mass is removed. Remaining solvent is desorbed during crosslinking at 120 ± 5 °C for 25–30 min. Below 115 °C, residual solvent remains above 0.8 wt%, raising volume resistivity from 4.2×10⁻⁵ Ω·cm to above 1.1×10⁻⁴ Ω·cm and reducing ITO/PET adhesion to class 2B or lower when tested to ASTM D3359-17. Above 130 °C, PET substrates exhibit machine-direction shrinkage greater than 0.8%, causing bus-bar width loss and delamination at printed edges. The cure window is therefore 120 ± 5 °C, with forced-air oven setpoint variation maintained at ±2 °C.
Silver flake loading is controlled at 82 ± 2 wt%. At 84 wt%, Brookfield viscosity at 10 rpm rises above 45,000 mPa·s, thixotropic index above 6.0, and 325-mesh screen life decreases from 2,500 impressions to fewer than 400 impressions before mesh plugging. At 80 wt%, through-plane thermal conductivity falls below 2.5 W/(m·K). The formulation is therefore positioned at the edge of the rheology–thermal conductivity trade-off. Convection infrared hybrid ovens with 2.4–3.6 m heated length and zone temperatures of 80 °C, 110 °C, and 120 °C are used for roll-to-roll processing at 0.8–1.2 m/min. Conventional high-temperature silver pastes require 180–250 °C for 30–60 min, or 450–850 °C for ceramic thick films; this product is intended for substrates with heat deflection temperatures below 140 °C.
Comparative property matrix of HTC-LT-240 EL and a conventional polymer thick-film silver is provided below. Values are measured on 25–30 µm dry film thickness after curing at the stated schedule. The table is used for batch-to-batch lot release and application screening, not as a substitute for device-level qualification.
| Property | Test Method | HTC-LT-240 EL | Conventional PTF Silver |
|---|---|---|---|
| Viscosity at 25 °C, 10 rpm | ISO 3219 | 22,000–28,000 mPa·s | 18,000–24,000 mPa·s |
| Thixotropic index, 1 rpm/10 rpm | ISO 3219 | 4.0–5.5 | 2.5–3.5 |
| Silver content | ASTM E1131 | 82 ± 2 wt% | 68–72 wt% |
| Volume resistivity after cure | ASTM F1896 | 4.2×10⁻⁵ Ω·cm | 1.8×10⁻⁴ Ω·cm |
| Sheet resistance at 25 µm | ASTM F1896 | 12–15 mΩ/sq | 35–50 mΩ/sq |
| Through-plane thermal conductivity | ISO 22007-2 | 3.2–4.2 W/(m·K) | 1.2–1.8 W/(m·K) |
| Adhesion to ITO/PET | ASTM D3359-17 | 4B | 3B |
| Flexure, 5 mm bend radius | IPC-TM-650 2.4.3.1 | 20,000 cycles without delamination | 2,000 cycles with edge cracking |
| Cure schedule | Forced-air box oven | 120 °C / 25 min | 150 °C / 30 min |
These values are representative batch lot release limits. The key differentiation is the combination of low-temperature cure and higher thermal transport. Conventional polymer thick-film silver systems with 68–72 wt% silver do not reach 2.0 W/(m·K) without cure at 150 °C or above. The HTC-LT-240 EL system achieves the higher transport through bimodal silver flake packing and controlled flake orientation during screen printing.
High thermal conductivity is meaningful when the printed film provides low thermal resistance per unit area. For a 25 µm dry film with thermal conductivity of 3.8 W/(m·K), the film thermal resistance is approximately 6.6×10⁻⁶ m²·K/W. In an EL lamp stack, the silver rear electrode is printed over a 35–50 µm phosphor-dielectric layer on ITO/PET. Heat generated in the phosphor must cross the dielectric and silver rear electrode; a conventional PTF silver with 1.5 W/(m·K) at 25 µm adds 1.67×10⁻⁵ m²·K/W, more than double. This can increase local phosphor grain temperature by 8–14 °C at 400 Hz, 115 V AC operating conditions, depending on emissivity and air convection. The measurement is performed on cured free-standing films by transient plane source under ISO 22007-2, but published data for this specific EL configuration is limited; device-level thermal resistance should be validated by infrared thermography at 50 µm spatial resolution. Thermal cycling from -40 °C to 85 °C for 500 cycles per IEC 60068-2-14 causes less than 10% sheet resistance increase when the ink is printed on chemically stabilized PET. Under 60 °C/90% RH for 1,000 h per IEC 60068-2-78, sheet resistance drift is less than 15%, but adhesion may decrease if substrate surface energy is below 38 mN/m or corona treatment intensity is less than 250 W·min/m².
Compatibility with ZnS:Cu phosphor and BaTiO₃ dielectric is evaluated by screen-printing the silver rear electrode onto a cured EL stack and measuring initial capacitance loss and 100 h luminous decay at 400 Hz, 115 V AC. Permitted capacitance shift after lamination at 120 °C is less than 3%. Higher silver paste acidity or residual solvent can attack the phosphor binder and cause a luminance half-life reduction greater than 20%. The HTC-LT-240 EL system uses a neutral binder with acid value below 3 mg KOH/g and residual extractables below 0.5 wt% after full cure, so phosphor interaction is minimized. This is a key point of difference from general-purpose electronic silver pastes that do not specify low outgassing or low acidity for EL phosphor stacks.
For roll-to-roll flatbed screen printing, a 77 Shore A polyurethane squeegee with 60° blade angle and 15–25 mm/s flood speed is used. Print speed is set between 60 mm/s and 120 mm/s, with snap-off of 0.5–1.5 mm. On 250 mesh plain-weave stainless steel screens with 30 µm emulsion thickness, wet film thickness after printing is 35–40 µm, yielding 22–28 µm dry film after drying. In high-humidity environments above 60% RH, the printed film must be pre-dried at 50 °C for 15 min before entering the final cure zone to prevent moisture-induced pinholes and silver flake agglomeration at the film surface. Thinner deposits below 18 µm dry film may exhibit thermal resistance above 1.0×10⁻⁵ m²·K/W and are not recommended for high-brightness EL devices. Edge curl and mesh marks are controlled by maintaining paste temperature at 23 ± 2 °C and restoring thixotropic structure by gentle paddle stirring for 2–3 min before use; high-speed shear mixing is avoided because it introduces air bubbles and reduces screen working life.
The product is shipped in sealed jars and should be stored at 0–10 °C in an upright position. Warm-up time to 23 ± 2 °C is 4 h before opening to avoid condensation on the paste surface. Open containers have a pot life of 8 h at 23 ± 2 °C and 50 ± 10% RH; beyond this interval, viscosity drift exceeds 10%, and screen release becomes inconsistent. Solvent entrapment occurs when the drying ramp exceeds 5 °C/min: a skin forms before buried solvent desorbs, causing blistering during final cure and volume resistivity above 1.0×10⁻⁴ Ω·cm. The paste should not be blended with amine-based crosslinkers, acid-containing adhesion promoters, or silicone release agents; amines accelerate binder chain extension, acids corrode silver flake surfaces, and silicones reduce adhesion to ITO. Halide and sulfur contamination limits are specified because residual chloride is a known initiator of ITO degradation in flexible EL devices. End-use qualification should include 85 °C/85% RH damp-heat exposure for 500 h and 20,000-cycle flex testing, because published data for long-term field aging of this specific formulation is limited. The material is not intended for direct contact with silver migration-sensitive fine-pitch circuits at DC bias above 12 V/mm without conformal coating or solder mask protection.
