Ensinger TECAFIL PEEK LDS black is a 1.75 mm diameter fused filament fabrication grade based on polyetheretherketone compounded with a mineral fiber reinforcement and a laser-direct-structuring additive. The filament is supplied in black and is intended for high-temperature extrusion systems with all-metal hot ends. The PEEK matrix typically exhibits a melt temperature near 343 °C and a glass transition temperature near 143 °C when evaluated by ISO 11357-3. The mineral fiber component reduces the coefficient of linear thermal expansion relative to unfilled PEEK, while the LDS additive permits selective electroless metal deposition after laser activation. Outside the laser-written tracks, the printed dielectric remains electrically insulating. The combination is therefore positioned for additively manufactured substrates that require circuit trace formation without a separate conductive ink or catalytic coating operation.

What Limits Laser Direct Structuring on Unfilled PEEK Surfaces?

Unfilled PEEK filaments do not contain a laser-activatable metal complex. Metallization of unfilled PEEK surfaces requires either plasma or wet-chemical etching followed by palladium seeding, or screen printing of conductive pastes. These routes introduce additional process deviation because the adhesion of palladium catalysts to PEEK is sensitive to surface oxidation and crystallinity gradients produced during fused filament fabrication. Production-scale FFF lines report that layer-bond voids at sidewalls create discontinuous seed coverage, producing open circuits in electroless copper. The LDS additive in TECAFIL PEEK LDS black is dispersed through the filament and is activated only where the laser scans the surface; this narrows the metallization boundary relative to wet-chemical activation. Printed substrates therefore retain a bulk resistivity characteristic of the filled PEEK dielectric, with no continuous conductive phase in unlasered regions. Surface insulation and volume resistivity values should be verified at the finished part level according to ASTM D257 or IEC 62631-3-1.

Product-specific dimensional control for the 1.75 mm filament is typically specified at ±0.05 mm on diameter; this tolerance must be confirmed against the certificate of analysis because ovality above 0.03 mm can generate melt-pressure fluctuation in direct-drive high-temperature extruders. The filler package raises melt viscosity relative to unfilled PEEK, so printing without an actively heated chamber often results in interlayer delamination. The material is recommended for drying at 150 °C for 4–6 h in a desiccant dryer with a dew point at or below -40 °C. PEEK filament exposed to 50 % RH at 23 °C can absorb sufficient water to produce surface hydrolysis during extrusion; this appears as irregular extrudate diameter and reduced interlayer adhesion. A moisture content below 0.10 % by weight is a common control limit for PEEK feedstocks before high-temperature extrusion.

When the Filament Is Processed on a Heated-Chamber FFF Platform

Process control for TECAFIL PEEK LDS black requires extrusion barrel temperatures in the range of 400 °C to 430 °C. The final nozzle setpoint should be adjusted to match the actual melt thermocouple reading because thin-film heater block lag can produce a true melt temperature 10–15 °C below the setpoint on some production printers. A heated build plate at 160–200 °C and a chamber temperature between 90 °C and 180 °C are typical operating boundaries. At chamber temperatures below 90 °C, the part cools through the PEEK glass transition before the next layer is applied, resulting in poor polymer chain interdiffusion across the layer interface. Layer tensile strength in PEEK is therefore highly dependent on chamber conditions; published data for this specific configuration is limited, but general PEEK FFF studies show a nonlinear drop in z-direction strength when chamber temperature falls below the matrix Tg. The extruder must be fitted with a hardened steel or ruby nozzle, and a PTFE-lined hot end is incompatible with the required melt temperature.

Residual stress relaxation after printing is performed at temperatures between 200 °C and 250 °C for 2–4 h under nitrogen or vacuum. Annealing below 200 °C is generally insufficient to relax oriented polymer chains near the nozzle stagnation point, while annealing above 260 °C may initiate surface oxidation of the LDS additive and should be avoided unless the furnace atmosphere is inert. Mineral fiber reduces global shrinkage compared with unfilled PEEK, but the part still exhibits anisotropic shrinkage because the raster direction retains oriented fiber and polymer domains. The coefficient of linear thermal expansion for mineral-filled PEEK is typically in the range of 35–50 µm/m·K between 23 °C and 150 °C measured by ASTM E831 or ISO 11359-2; unfilled PEEK may be closer to 50–60 µm/m·K in the same interval.

For selective metallization, laser activation is typically carried out with focused near-infrared radiation at 1,064 nm or 1,070 nm, depending on the LDS system. The exposed additive initiates electroless copper deposition. In 3D-MID production, electroless copper thickness is commonly controlled in the range of 5 µm to 12 µm, followed by electroless nickel at 2 µm to 5 µm and, where required, immersion gold at 0.05 µm to 0.10 µm. Plating adhesion is influenced by the laser scan energy, the surface roughness of the printed part, and the degree of polymer crystallinity at the surface. When the part is subsequently exposed to lead-free reflow soldering with peak temperatures near 260 °C, the PEEK matrix remains dimensionally stable, but the plated stack must be qualified for thermal shock because metal-polymer CTE mismatch can produce microcracking at the trace edge.

Mineral Fiber Reinforcement, CLTE Reduction, and Annealing Response

The mineral fiber in TECAFIL PEEK LDS black is selected for dielectric compatibility with the LDS additive. Unlike carbon fiber-filled PEEK, which exhibits non-negligible electrical conductivity and can interfere with electroless copper selectivity, the mineral filler remains electrically insulating. Mechanical data for mineral-filled PEEK grades typically show tensile strengths between 90 MPa and 110 MPa and tensile moduli above 4,000 MPa when tested according to ISO 527-2; elongation at break is generally below 5 %. These values are not a substitute for the manufacturer’s datasheet for this specific filament, because filler loading and LDS additive content shift short-term mechanical response. The mineral reinforcement reduces print shrinkage, but it also lowers fracture toughness; thin-wall sections below 1.0 mm can be notch-sensitive at layer interfaces. Post-build annealing raises the crystalline fraction and may reduce residual stress, but it can also increase brittleness in the same thin sections.

Comparative Behaviour Against Carbon-Filled and Unfilled PEEK Feedstocks

Three distinctions govern material selection. First, unfilled PEEK provides higher ductility, but its high crystallinity-driven shrinkage and absence of an LDS additive make it unsuitable for selective metallization without additional activation. Second, carbon fibre-filled PEEK offers higher stiffness and lower CLTE, but the carbon phase creates surface conductivity that can short-circuit adjacent traces and is incompatible with LDS selectivity. Third, TECAFIL PEEK LDS black occupies an intermediate position in which the mineral fiber controls thermal expansion while the dielectric filler and LDS additive preserve a non-conductive bulk. The following table summarises the differentiation.

Storage conditions for partially consumed spools are critical because the mineral fiber can increase moisture wicking along the filament surface. Once removed from vacuum-sealed packaging, the spool should be stored in a dry-air cabinet with dew point below -30 °C or in a desiccant container with fresh molecular sieve. If a spool remains outside controlled storage for more than 8 h at 50 % RH, re-drying at 150 °C for 4–6 h is required before further extrusion. Repeated drying cycles above 7 are generally not recommended because prolonged thermal exposure can degrade the LDS additive and reduce plating adhesion on subsequent builds.

Operational boundaries extend beyond the heated chamber. The filament must not be processed in hot ends containing PTFE or PFA components; thermal degradation of these fluoropolymers begins above 260 °C and can release acidic species that catalyse PEEK degradation. The LDS additive is sensitive to melt residence time; extended hold-up above 30 min at processing temperature can darken the melt and reduce subsequent plating adhesion. Compliance is defined at the finished article level: the PEEK base polymer is often assessed for REACH and RoHS conformity, but the final plated MID must be evaluated separately because electroless nickel and copper layers introduce their own regulatory considerations. Avoid combinations with amine-based processing aids or epoxy hardeners in downstream bonding steps, as residual amine species can accelerate PEEK degradation and may contaminate the laser-activated surface before electroless plating.