Parker Chomerics THERMATTACH T405-R is a double-sided, reinforced thermally conductive pressure-sensitive adhesive tape supplied as roll stock on a differential release liner. The product consists of a filled acrylic pressure-sensitive adhesive carried on a reinforced carrier; the -R designation in Parker Chomerics product literature identifies the reinforced construction that stabilises die-cut parts and restricts adhesive squeeze-out under nip or platen pressure. The tape is used to bond stamped aluminium heat sinks, exposed-pad semiconductor packages, LED modules, and other low-to-moderate power assemblies without threaded fasteners or spring clips. Because the adhesive film is itself the thermal interface, junction temperature rise is governed by bond-line thickness, surface wet-out, void formation, and applied lamination pressure rather than by bulk pad deflection. Published typical thermal conductivity for T405-R is 0.6 W/(m·K) when tested in accordance with ASTM D5470; the product is converted at total thicknesses of 0.127 mm to 0.254 mm depending on required conformability and thermal impedance.

For initial design evaluation, the typical property set in Table 1 is used with the caveat that values are not specification limits and will shift with substrate finish, lamination pressure, and lot-to-lot variation. Peel adhesion and dielectric performance should be reconfirmed on production substrates because acrylic pressure-sensitive adhesive behaviour is strongly influenced by surface energy and roughness.

Which qualification standards are cited for T405-R thermal, electrical, and adhesion data?

Thermal conductivity values are reported against ASTM D5470-17, which imposes one-dimensional heat flux through the specimen between temperature-controlled meter bars. Because apparent thermal conductivity includes interfacial contact resistance, the reported value is not solely a bulk material property and will vary with surface finish and applied test pressure. Adhesion data are obtained with ASTM D3330 peel panels at 180° and a crosshead speed of 300 mm/min; lap shear data, where required for structural evaluation of the bond line, are generated in accordance with ASTM D1002 using stainless steel coupons. Electrical insulation values are measured under ASTM D149-20 for dielectric breakdown and ASTM D257-14 for volume resistivity. For sealed-enclosure or space applications, outgassing should be requested from the manufacturer in the form of ASTM E595 total mass loss and collected volatile condensable material values.

The dielectric breakdown result in Table 1 is a short-time test result and does not capture partial discharge or tracking behaviour under PWM inverter waveforms in high-voltage applications. Creepage and clearance distances should be designed according to IEC 62368-1 or IEC 60664-1. When the tape is placed between a heat sink and a live electrical tab, the tape edge should be recessed at least 0.5 mm from the metal edge to reduce surface tracking risk.

In die-cut conversion, T405-R is kiss-cut through the adhesive and reinforced carrier to the primary release liner without cutting the secondary liner. This produces individually removable parts for automated pick-and-place. Rotary die-cutting is preferred for high-volume geometries because the continuous web path avoids adhesive stringing and liner curl associated with flatbed dwell time. Blade depth is typically set to within 0.012 mm of the carrier–liner interface; liner fracture below 0.008 mm of the interface creates pick-and-place failures in high-speed placement heads. Flatbed and galvo-laser cutting are reserved for prototype builds. Published data for laser cutting of this specific reinforced tape configuration is limited, so edge char and liner damage should be validated on short runs before production release.

Attachment is carried out by removing the liner, positioning the die-cut tape on the heat sink or component, and applying pressure through a compliant elastomer nip roll or flat platen. Bonding pressure of 0.2 MPa to 0.6 MPa is common for aluminium substrates; pressure below 0.1 MPa can leave microvoids at the adhesive–substrate interface. Because acrylic pressure-sensitive adhesion forms by viscoelastic wet-out rather than cure chemistry, no dwell time is required for crosslinking. Peel strength nevertheless continues to increase over 24 h to 72 h at 20 °C to 25 °C as the adhesive flows into microscopic substrate roughness. Assemblies should not be subjected to peel or shear loads immediately after lamination if design margins are below 1.5.

Surface preparation for aluminium and copper consists of an isopropanol wipe followed by dry compressed air. Abrading anodised surfaces is generally avoided because the tape is not a gap filler and loose particles can become trapped at the thermal interface. Surface energy should be at least 38 mN/m; surfaces below this threshold require a primer or plasma treatment. Untreated polyolefin is not recommended, and published adhesion data for this configuration on untreated polyolefin is limited.

Roll stock should be stored at 10 °C to 30 °C and 40% to 60% relative humidity. Open rolls should be resleeved after each conversion run; liner curl and adhesive pickup are observed on converting floors when exposed rolls remain outside controlled humidity for more than 8 h. Shelf life from date of manufacture is 12 months in original packaging.

Thermal impedance in a bonded assembly is the sum of bulk adhesive-and-carrier conduction and two interfacial contact resistances. For a 0.254 mm bond line at 0.6 W/(m·K), the bulk component alone is 4.2 K·cm²/W. In a 1000 mm² contact area carrying 5 W, the ideal bulk temperature rise is therefore 2.1 K; interfacial voids and roughness can increase this value by 30% to 80% if lamination pressure is inadequate. This is why thermal qualification should be based on ASTM D5470 apparent thermal impedance measured at the intended bond-line thickness and pressure rather than bulk thermal conductivity alone.

When the reinforced T405-R build is set beside non-reinforced thermal transfer tapes

Three product-level differences dominate selection. First, the reinforced carrier in T405-R restricts adhesive squeeze-out under static clamp load; non-reinforced transfer tapes can thin under edge pressure and produce inconsistent thermal impedance across the interface. Second, the carrier increases dimensional stability during rotary die-cutting, permitting narrower webs and tighter part tolerances. Third, the carrier reduces elongation during liner stripping but increases bending stiffness. The trade-off is conformability: T405-R should not be expected to fill a non-uniform gap larger than its total thickness. If flatness deviation exceeds 0.1 mm across the contact area, a cured gap pad or dispensed thermally conductive gel must be used.

When compared with non-reinforced acrylic transfer tapes, T405-R shows lower uncontrolled thinning under compression and better kiss-cut part release on high-speed converting lines. A non-reinforced tape may wet out a slightly rough surface at lower nip pressure because the carrier does not resist local deformation; however, that same material is more prone to edge ooze and dimensional distortion during liner stripping. The selection between the two should therefore be driven by bond-line topography and converting tolerance, not by thermal conductivity alone.

T405-R is not intended for lead-free solder reflow; the adhesive system is not a replacement for a reflow-stable cured silicone pad. Continuous service above 125 °C accelerates oxidative degradation of the acrylic polymer, and shear load capacity declines as temperature approaches the adhesive glass-transition. The tape does not supply a sustained clamp force over thermal cycling; assemblies with mismatched coefficients of thermal expansion or continuous vibration should include mechanical retention. Plasticized PVC, silicone-rich surfaces, and certain casting-release agents can migrate into the adhesive and reduce peel force. For power dissipation above 10 W per component, a cured pad or dispensed gap filler may be required because the thermal impedance of a thin PSA bond line is higher than that of a bulk gap-filling elastomer. The design decision should be based on measured ASTM D5470 thermal impedance at the as-laminated thickness, ASTM D1002 lap shear after thermal aging, and production-grade surface roughness rather than on bulk thermal conductivity alone. Published data for T405-R under cyclic humidity aging on aluminium-clad PCBs is limited.