Thermal epoxy adhesive

Thermal epoxy is a thermosetting polymer loaded with metal-oxide or ceramic filler that, once cured, becomes a rigid, high-modulus structural bond with dual function — mechanical fastening plus a thermal conduction path. Compared to RTV silicone adhesive (TIS580), epoxy gives higher lap-shear strength (typical 8 – 20 MPa vs 1 – 3 MPa for RTV silicone), stiffer post-cure modulus, and better moisture resistance, at the cost of brittleness under thermal cycling and the need for a heat cure step. Pick epoxy when the joint must replace a screw or rivet; pick silicone when the joint must absorb mechanical or thermal-cycle stress.

Both TIE380-25 and TIE380-45 are single-part (1K) heat-cure formulations — pre-mixed, ready to dispense from cartridge or syringe, no Part-A/Part-B mixing required. They cure on a heated platen or in a reflow oven (typical 130 °C / 30 min). For two-component room-temp-cure structural bonding our two-part TIE280-AB potting epoxy line gives a longer pot-life with no oven needed; see the epoxy-potting-compound family for that workflow.

TIE380 series is electrically insulating (volume resistivity ≥ 10¹³ Ω·cm typical) — the ceramic filler provides thermal conduction without forming a continuous metal path, so a thin bondline between an LED can and a copper heatsink will not short. Verify the dielectric strength on the datasheet for the specific grade if your bondline is operating above 100 V; some grades will derate at very thin bondlines under high-voltage conditions.

For maximum thermal performance, target the thinnest bondline that still gives full coverage and tolerates the part-to-substrate flatness — typically 50 – 200 µm. Thinner bondlines reduce thermal resistance linearly with thickness, so 50 µm at 2.5 W/m·K gives lower interface resistance than 200 µm at 4.5 W/m·K. Use a controlled clamp pressure or shim during cure to lock the bondline; once cured, the joint is permanent and cannot be reworked without breaking the substrates.

Cured TIE380 epoxy is a permanent structural bond — by design, it cannot be peeled or melted off. Removal requires either mechanical fracture (chisel, ultrasonic) or solvent attack (chlorinated or strong polar solvents) which usually damages the substrate. If reworkability is on the spec, switch to TIA800 thermal adhesive tape (peel-and-replace) or TIS580 RTV silicone adhesive (can be cut and re-bonded).

TIE380-25 and TIE380-45 are rated −40 °C to +150 °C continuous service. Above 150 °C the epoxy backbone will gradually oxidise (Tg around 110 – 120 °C means modulus softens before chemical degradation begins). For silicone-class continuous-service ranges (−50 to +200 °C and beyond) use TIS580 RTV silicone adhesive or one of the silicone potting compounds.