| HS Code | 278447 |
| Dielectric Constant | 2.45 (at 10 GHz) |
| Dissipation Factor | 0.0008 (at 10 GHz) |
| Water Absorption | 0.05% (24h) |
| Tensile Strength | 12 MPa |
| Elongation At Break | 650% |
| Flexural Modulus | 150 MPa |
| Peel Strength To Copper | 1.2 N/mm |
| Glass Transition Temperature | -70°C |
| Volume Resistivity | 1e16 ohm·cm |
| Surface Resistivity | 1e15 ohm/sq |
As an accredited SBS/SEBS Resin for Flexible High-Frequency PCB Substrates factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Sealed, moisture-proof aluminum foil bags with nitrogen purge, 25 kg net each, preserving SBS/SEBS resin purity for flexible high-frequency PCB substrates. |
| Container Loading (20′ FCL) | 20′ FCL loading: SBS/SEBS resin packed in sealed bags on pallets, secured to prevent shifting during transport. |
| Shipping | This resin is shipped in sealed, moisture-proof drums or bags to preserve purity. Transport at ambient temperature, avoiding direct sunlight and extreme humidity. Handle with care to prevent damage, and ensure proper labeling for chemical transport. Standard industrial logistics apply, with no special hazardous classification under normal conditions. |
| Storage | Store SBS/SEBS resin in a cool, dry, well-ventilated area, away from direct sunlight, heat, sparks, and open flames. Keep containers tightly sealed to prevent moisture absorption and oxidation. Ideal storage temperature is below 25°C. Avoid prolonged air exposure. Follow manufacturer’s shelf-life guidelines to maintain purity and performance for flexible PCB substrates. |
| Shelf Life | Shelf life: 12 months from manufacture when stored sealed in a cool, dry place away from direct sunlight. |
Flexible high-frequency PCB substrates that incorporate SBS and SEBS resins as dielectric binders or adhesive tie layers require substrate-level validation across the full signal integrity chain. SBS grades are typically restricted to sub-6 GHz cost-optimised constructions because of higher allylic unsaturation and oxidation sensitivity; hydrogenated SEBS grades occupy the millimetre-wave low-loss window when combined with low-polarity tackifiers and spherical ceramic fillers. The following application zones are limited to sectors where SBS/SEBS-based films, bonding sheets, or coverlay adhesives have been placed on production-scale equipment: slot-die coaters, reverse roll coaters, co-rotating twin-screw compounding lines, and vacuum lamination presses. In each zone, the resin addition window, governing standard test method, lamination/coating process, and terminal product category are treated as inseparable.
Roll-to-roll slot-die coating of ceramic-filled polyolefin elastomer dielectric pastes used in 5G NR millimetre-wave antenna flex circuits begins with a SEBS-rich binder phase that balances dielectric loss against copper peel strength. Compliance for this construction is assessed under IPC-TM-650 Method 2.5.5.13 for relative permittivity and loss tangent at 10 GHz, ASTM D150-18 for AC loss characteristics, and UL 94 VTM-0 for thin-film flame propagation; RoHS Directive 2011/65/EU restricts the use of brominated flame retardants that would otherwise raise dissipation factor. The formulation window reported in published technical literature places SEBS at 20–35 phr of total solids, hydrogenated C9 tackifier at 5–12 phr, spherical silica at 20–40 wt%, and phosphorus/nitrogen flame retardant at 12–20 phr; the exact ratio is adjusted because silica content above 40 wt% produces a non-linear increase in paste viscosity and edge cracking on 12–25 μm copper foil. Downstream production involves dispersing the resin and fillers in a toluene/MEK/cyclohexanone solvent blend at 25–40% solids, filtering through 5–10 μm absolute cartridge filters, and coating onto roll-annealed low-profile copper foil at 10–20 m/min with a slot-die gap of 150–250 μm; oven zones at 80–120°C remove residual solvent to below 0.2 wt%, after which the coated foil enters a vacuum lamination press at 170–190°C under 2–4 MPa for 60–90 min to densify the dielectric. Terminal product types include 5G NR FR2 antenna modules, flexible printed circuit interconnects for smartphone phased arrays, and millimetre-wave IoT sensor boards; published data for SEBS-based dielectric films in FR2 antenna modules remains limited beyond laboratory-scale insertion loss studies.
In 77 GHz automotive radar flexible harness substrate production, the bonding sheet is cast from a toluene/cyclohexanone dispersion and then evaluated by IPC-TM-650 Method 2.4.8 for peel strength and Method 2.6.3.3 for surface insulation resistance; the finished flex board is qualified under IPC-6013D Class 3. The processing boundary is set by oxidation of the styrene-ethylene-butylene midblock at solder float temperature: retention failures occur when the bonding sheet is under-cured or when residual solvent exceeds 0.5 wt% before lamination. Formulation addition ratios in this segment fall within SEBS-g-MAH 25–35 phr, hydrogenated C9 resin 8–15 phr, spherical silica 10–25 wt%, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane peroxide 0.3–0.8 phr; higher peroxide loadings raise crosslink density but reduce melt flow and peel strength to below 0.6 N/mm after thermal stress. Downstream production uses a reverse roll coater to cast the adhesive onto release-treated polyester film at 15–30 m/min, followed by a 90–120°C drying tunnel with solvent recovery, then B-staging at 130–150°C before inline lamination to polyimide; production-scale failure is typically observed as blistering at RH > 65% unless pre-drying at 105°C for 24 h is enforced. Terminal product types include aerospace rigid-flex backplanes, high-layer-count cockpit display interconnects, and engine control flex harnesses that require 288°C solder float compatibility.
| SEBS-g-MAH (phr) | Hydrogenated C9 tackifier (phr) | Silica (wt%) | Post 288°C solder float peel strength (N/mm) | Observed lamination failure mode |
|---|---|---|---|---|
| 20 | 5 | 15 | 0.55–0.70 | Copper-side adhesive transfer |
| 30 | 10 | 20 | 0.80–1.00 | No blistering with pre-dried film |
| 40 | 15 | 25 | 0.60–0.75 | Non-linear viscosity rise, edge voiding |
Under 150°C thermal ageing, the stability of SEBS-based flexible substrates is governed by antioxidant package efficiency and filler surface chemistry. The substrate is expected to retain 90% of initial peel strength after 1,000 h at 150°C when evaluated per IPC-TM-650 Method 2.4.8; dielectric constant stability is checked under ASTM D150-18 at 1 MHz and 10 GHz, and the material is qualified against ISO 16750-4 thermal load profile for automotive electrical/electronic equipment. The resin addition ratio in radar harness substrates uses SEBS 18–28 wt%, PTFE micropowder 5–10 wt%, fused silica 30–45 wt%, and hindered phenol/phosphate antioxidant 0.5–1.5 phr; the PTFE content is limited to 10 wt% because dispersion above that threshold causes melt fracture during cast film extrusion. Downstream manufacturing compounds the formulation on a co-rotating twin-screw extruder with L/D 40:1 at 180–220°C, pelletises, and then cast-extrudes a 50–75 μm film at 180–210°C before thermal lamination to 18 μm low-profile copper foil at 190–210°C and 3–5 MPa. Terminal product types include 77 GHz automotive radar flexible harnesses, ADAS sensor flat flex jumpers, and blind-spot detection antenna carriers; operational limits are set by continuous-use temperature above 125°C where the SEBS phase undergoes oxidative chain scission unless stabiliser loading is increased.
When low-loss coverlay replaces acrylic adhesive in 60 GHz phased-array interposers, the adhesive layer is reformulated around a hydrogenated SEBS backbone to keep insertion loss below 0.5 dB/in at 60 GHz; qualification is conducted under IPC-TM-650 Method 2.5.5.13 at 10 GHz, Method 2.5.5.5 for permittivity and loss tangent, and IPC-4101E slash sheet requirements for low-loss flexible dielectrics. The addition window is 15–25 wt% SEBS, 5–10 wt% hydrogenated cycloaliphatic tackifier, 20–30 wt% boron nitride or aluminium nitride, and 5–15 wt% phenolic phosphate flame retardant; boron nitride above 30 wt% lowers tack and creates lamination voids at 180°C unless solvent dilution is increased. The downstream process reverse roll coats the coverlay adhesive onto 12.5 μm polyimide film at 20–35 m/min, dries in three zones from 70°C to 110°C, and laminates to a low-loss LCP or PTFE-based base substrate at 170–190°C under 2–3 MPa; volatile content is maintained below 0.3 wt% to meet NASA outgassing limits for space-grade assemblies under ASTM E595-15. Terminal product types include Ku/Ka-band phased-array antenna interposers, satellite user terminal flex layers, and 60 GHz point-to-point radio antenna boards; incompatibility with amine-based adhesion promoters must be controlled because residual amines accelerate oxidative degradation of the SEBS midblock during high-temperature ageing. Published data for this specific configuration is limited beyond subscale qualification reports, so the insertion-loss target should be revalidated on the final laminate stack-up.
Solventless lamination adhesive for wearable biosensor flexible circuits is compounded from silane-grafted SEBS to eliminate extractable solvent residues and to maintain bond strength after 50 cycles of simulated sweat immersion; biocompatibility is assessed under ISO 10993-5 for cytotoxicity and ISO 10993-10 for skin sensitisation, while the finished flexible circuit is tested under IPC-6013D Class 2 for flexural endurance. The formulation addition ratio uses silane-grafted SEBS 35–50 phr, medical-grade white oil 10–20 phr, hydrophobic fumed silica 5–15 wt%, and antioxidant 0.3–0.8 phr; the white oil and silica are controlled to keep Shore A hardness below 65 because stiffer adhesive films induce skin-contact edge lift. Downstream production runs through a hot-melt slot-die coater at 120–150°C, with the adhesive applied at 25–40 μm thickness directly to a thermoplastic polyurethane or polyimide carrier, followed by lamination to 18 μm rolled-copper foil at 100–120°C under 1–2 MPa; the use of no solvent permits direct lamination without explosion-proof drying infrastructure. Terminal product types include ECG electrode flex circuits, wearable glucose sensor interconnects, and disposable body-temperature logging patches; silicone-based release liners are incompatible because silicone oil migration reduces subsequent copper adhesion.
During co-rotating twin-screw extrusion of SEBS/ceramic masterbatch for high-speed data centre flexible backplane insulation, the resin is used as a compatibilised binder that reduces melt viscosity and enables 50–65 wt% ceramic loading without excessive torque. The governing standards are IPC-4101E for base material consistency, IPC-TM-650 Method 2.5.5.9 for dielectric breakdown, and UL 94 VTM-0 for flame retardance in thin films. Formulation addition ratios are SEBS-g-MAH 20–30 wt%, cycloaliphatic tackifier 5–8 wt%, alumina or silica 45–60 wt%, and phosphorus-based flame retardant 10–15 wt%; torque limits on a 40:1 L/D co-rotating twin-screw extruder are maintained below 85% of rated motor load by splitting filler feed into downstream side stuffers. Downstream production compounds at 180–220°C with a screw speed of 300–500 rpm, pelletises under nitrogen, and then extrudes a 75–125 μm dielectric film through a flat die at 190–210°C before inline lamination to 35 μm copper foil at 190–210°C and 3–4 MPa. Terminal product types include 112G and 224G data centre flexible backplane interconnects, server power flex busbars, and high-speed switch fabric flexible layers; the operational boundary is set by moisture absorption above 0.2 wt% in the ceramic filler, which creates microvoids and raises insertion loss at 56 GHz. Published data for SEBS/ceramic masterbatch at 224G data rates is limited, and signal integrity validation must be performed on the finished flexible backplane rather than the cast film alone.
| End market | Governing standard | Test method | Critical threshold |
|---|---|---|---|
| 5G NR antenna flex | UL 94 | VTM-0 | No flame propagation |
| Automotive radar | ISO 16750-4 | Thermal cycle | 1,000 h at 150°C peel retention |
| Phased-array interposer | IPC-4101E | TM 2.5.5.13 | Df ≤ 0.005 at 10 GHz |
| Wearable biosensor | ISO 10993-5 | Cytotoxicity | ≥ 70% cell viability |
| Data centre busbar | UL 94 | VTM-0 | Self-extinguish within 10 s |
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Styrene-butadiene-styrene (SBS) and hydrogenated styrene-ethylene/butylene-styrene (SEBS) block copolymers are supplied as pelletized dielectric binders for flexible high-frequency printed circuit board substrates. The product family evaluated for two-layer copper-clad laminates and coverlay bondplies comprises three melt-flow variants: a low-flow SEBS with melt flow rate from 5 g/10 min to 8 g/10 min at 230 °C/5 kg, a medium-flow SEBS with melt flow rate of 22 g/10 min at 230 °C/5 kg, and a linear SBS with melt flow rate below 1 g/10 min at 200 °C/5 kg, all measured to ASTM D1238. The medium-flow SEBS has bound styrene 13 wt%, ethylene/butylene midblock 87 wt%, tensile strength 23.4 MPa by ASTM D412, elongation at break 750%, Shore A hardness 65, and specific gravity 0.90. A maleated SEBS variant with 1.4–2.0 wt% grafted maleic anhydride is used for direct adhesion to rolled-annealed or electrodeposited copper foil without an adhesive tie coat. The styrene hard domains have a glass transition near 95 °C and the ethylene/butylene midblock has a glass transition below -50 °C, giving a phase-separated morphology that retains peel strength up to 95 °C. In unfilled films, dielectric constant at 10 GHz measured by IPC-TM-650 2.5.5.5 is typically 2.3–2.4 and dissipation factor is 0.0008–0.0015. Ceramic-filled compounds achieve dielectric constant up to 3.5 while retaining dissipation factor below 0.004 at 10 GHz when filler dispersion is controlled. The linear SBS variant is selected only for low-temperature lamination below 180 °C; its unsaturated butadiene midblock raises dissipation factor at 10 GHz by approximately 0.001–0.002 relative to the hydrogenated SEBS variant.
Unfilled SEBS exhibits stable dissipation factor from 1 GHz to 28 GHz when processed below 230 °C. Addition of fused silica with median particle size 1.5 μm raises relative permittivity from 2.3 at 0 vol% filler to 3.5 at 40 vol% filler according to IPC-TM-650 2.5.5.5. Above 40 vol%, dissipation factor increases from 0.002 to 0.006 at 10 GHz because particle-particle contacts create local field concentrations and loss paths. The practical compounding limit on a 25 mm co-rotating twin-screw extruder with L/D 40:1 was 38 vol% fused silica for a 75 μm cast film. Beyond this loading, die pressure varied by more than 18% across a 300 mm slot die and film gauge standard deviation rose above 6 μm. At 35 vol% filler loading, complex viscosity at 1 rad/s and 220 °C increased from 1,900 Pa·s for the unfilled medium-flow SEBS to 6,800 Pa·s as measured by oscillatory rheometry according to ISO 6721-10. The shear-thinning exponent between 0.1 rad/s and 100 rad/s changed from 0.82 to 0.63, indicating that filler network formation dominates low-frequency rheology and narrows the cast-film processing window.
When storage relative humidity exceeds 60%, SEBS pellets absorb surface moisture to 0.08 wt% within 24 h. A desiccant hopper at 80 °C with 2 h residence reduces moisture to below 0.03 wt%, which is required before film extrusion. Film extruded from undried pellets showed microbubble density greater than 15 bubbles/cm² in a 75 μm web and insertion loss increase of 0.18 dB/cm at 28 GHz in a microstrip test vehicle. For SBS tie layers, the desiccant temperature is reduced to 60 °C; inlet air above 90 °C softens the styrene domains and causes pellet blocking. On a roll-to-roll vacuum laminator, copper lamination of a 50 μm maleated SEBS bondply onto rolled-annealed copper was operated at nip pressure 0.6 MPa, lamination temperature 210 °C, and dwell time 10 s. Peel strength by IPC-TM-650 2.4.9 was 1.1 N/mm. The same processing conditions with non-maleated SEBS produced 0.4 N/mm. After exposure to 85 °C/85% RH for 500 h, the maleated variant retained 0.8 N/mm peel strength, while the non-maleated variant fell below 0.2 N/mm. The loss is attributed to moisture attack at the copper oxide interface and weakening of interfacial carboxylate interactions.
In unfilled medium-flow SEBS, stable slot-die casting on a 25 mm extruder with L/D 40:1 was maintained at apparent shear rates up to 1,200 s⁻¹ at 220 °C. When 35 vol% fused silica was compounded, sharkskin melt fracture appeared at 300 s⁻¹ at the same melt temperature. Raising melt temperature to 230 °C shifted the onset of melt fracture to 600 s⁻¹, consistent with a zero-shear viscosity reduction from 1,900 Pa·s to 680 Pa·s for the unfilled matrix. Above 230 °C, maleated SEBS began to liberate acidic degradation products, creating pinholes in cast film; therefore the upper melt-temperature boundary was set at 230 °C. The practical filler limit for 75 μm film was 40 vol%, at which edge tearing and die-lip build-up occurred after 45 min continuous running. Die-lip build-up was removed only by increasing the die gap from 200 μm to 250 μm; this reduced pressure fluctuation from 112 bar to 86 bar but increased final film thickness variation to ±5 μm.
Compared with polyimide, SEBS eliminates the imidization cure step and reduces moisture absorption from 1.3–2.0 wt% to below 0.1 wt% after 24 h immersion by ASTM D570. Compared with polytetrafluoroethylene-ceramic binders, SEBS laminates at 190–230 °C rather than 350–380 °C, but its continuous use temperature is limited to 105 °C under peel-strength retention criteria. Compared with liquid-crystal polymer film, SEBS offers isotropic in-plane shrinkage below 0.6% after 2 h at 150 °C, while biaxially oriented LCP can differ by more than 0.3% between machine and transverse directions. Table 1 summarizes measured and supplier-reported values for five binder systems.
| Property | Method | SBS | SEBS | PTFE-ceramic | LCP | Polyimide |
|---|---|---|---|---|---|---|
| Dielectric constant at 10 GHz | IPC-TM-650 2.5.5.5 | 2.5–2.7 | 2.3–2.4 | 2.9–3.2 | 2.9–3.1 | 3.3–3.5 |
| Dissipation factor at 10 GHz | IPC-TM-650 2.5.5.5 | 0.001–0.003 | 0.0008–0.0015 | 0.0008–0.0012 | 0.002–0.004 | 0.005–0.010 |
| Moisture absorption, 24 h | ASTM D570 | 0.1–0.2% | 0.05–0.1% | 0.01–0.02% | 0.02–0.04% | 1.3–2.0% |
| Lamination or processing temperature | Process data | 150–180 °C | 190–230 °C | 350–380 °C | 320–360 °C | 250–350 °C |
| Peel strength to rolled-annealed copper | IPC-TM-650 2.4.9 | 0.8–1.2 N/mm | 1.0–1.5 N/mm, maleated | 0.6–1.0 N/mm, etched | 0.4–0.8 N/mm | 0.8–1.2 N/mm |
| In-plane shrinkage, 2 h/150 °C | IPC-TM-650 2.2.4 | 0.8–1.4% | 0.4–0.8% | 0.1–0.3% | 0.2–0.6% | 0.1–0.3% |
Aromatic hydrocarbons used as temporary carrier solvents induce swelling in SEBS. Toluene uptake by unfilled SEBS exceeds 200 wt% at 23 °C after 24 h, which changes film thickness by more than 50% and destroys dimensional stability. The ethylene/butylene midblock is selectively swollen; the styrene domains remain physically crosslinked but the compound becomes soft and weak. Polar aprotic solvents such as methyl ethyl ketone cause less swelling but extract low-molecular-weight diblock and plasticize the surface. When solvent-assisted lamination is unavoidable, the process is restricted to aliphatic hydrocarbon blends with less than 10% aromatic content and flash-off below 80 °C. Amine-based additives are incompatible with maleated SEBS. Primary amines react with grafted maleic anhydride at 190 °C within 2 min, increasing complex viscosity at 1 rad/s by more than 40% and producing gel specks larger than 100 μm in cast film. Phenolic antioxidants are acceptable at 0.3–0.5 wt% total loading; phosphorus acid stabilizers above 0.2 wt% can interfere with copper adhesion by migrating to the film surface.
The unfilled SEBS and 35 vol% silica-filled SEBS variants were screened against the compliance matrix in Table 2. The values represent internal laboratory results on 75 μm cast film and 50 μm bondply.
| Requirement | Standard | Condition | Result |
|---|---|---|---|
| Dielectric constant at 10 GHz | IPC-TM-650 2.5.5.5 | 23 °C, 50% RH | 2.3 unfilled; 3.3 at 35 vol% silica |
| Dissipation factor at 10 GHz | IPC-TM-650 2.5.5.5 | 23 °C, 50% RH | 0.001 unfilled; 0.003 at 35 vol% silica |
| Moisture absorption | ASTM D570 | 24 h immersion | 0.07% unfilled; 0.12% filled |
| Flammability | UL 94 | 75 μm film | V-0 with 30 wt% halogen-free flame retardant |
| REACH SVHC | EC 1907/2006, Article 33 | 0.1 wt% threshold | Not detected |
| RoHS restricted metals | 2011/65/EU, Annex II | Pb, Hg, Cr VI 1000 ppm; Cd 100 ppm | Below method detection limit |
| Extractable halogens | EN 14582 | Combustion ion chromatography | 900 ppm total Cl + Br |
Process operations above 250 °C in air are not recommended. The ethylene/butylene midblock of SEBS begins thermo-oxidative degradation near 270 °C; residence time above 5 min at 260 °C produces gel particles and increases melt pressure by more than 20%. For SBS, the upper melt-processing boundary is 180 °C in air because the unsaturated butadiene midblock crosslinks and discolors. Zinc stearate mold release is not used in copper-bonding grades because zinc carboxylate migrates to the surface and reduces peel strength by 0.3–0.5 N/mm.
