| HS Code | 839623 |
| Manufacturer | Sichuan EM Technology Co., Ltd. |
| Model | DFM1721-A |
| Product Type | RF dielectric band-pass filter |
| Center Frequency | 1721 MHz |
| Bandwidth | 70 MHz |
| Insertion Loss | ≤1.5 dB |
| Return Loss | ≥14 dB |
| Vswr | ≤1.5:1 |
| Impedance | 50 Ω |
| Power Handling | 10 W |
| Operating Temperature | -40°C to +85°C |
| Connector Type | SMA-F |
| Dimensions | 20 x 12 x 6 mm |
| Rohs | Yes |
As an accredited Sichuan EM Technology DFM1721-A factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Sichuan EM Technology DFM1721-A is supplied as 20 kg net in vacuum-sealed aluminum foil bags, within protective outer cartons. |
| Container Loading (20′ FCL) | 20′ FCL container loading for Sichuan EM Technology DFM1721-A, ensuring secure, compliant packaging and safe transport. |
| Shipping | Ships in sealed, corrosion-resistant containers with proper hazardous material labeling. Must be transported upright, kept dry, and away from incompatible substances. Temperature-controlled or ambient logistics per safety data sheet, with secure bundling and full documentation to ensure compliance and safe delivery. |
| Storage | Store Sichuan EM Technology DFM1721-A in its original, tightly sealed container in a cool, dry, well-ventilated area away from direct sunlight, heat, sparks, and open flames. Avoid moisture, humidity, and extreme temperatures. Keep incompatible materials separate. Handle with clean tools to prevent contamination. Always follow the manufacturer’s Safety Data Sheet for specific storage requirements and shelf life. |
| Shelf Life | Shelf life is 12 months from manufacture date if stored unopened in original container under recommended conditions. |
In halogen-free FR-4 prepreg production, Sichuan EM Technology DFM1721-A is handled as a reactive phosphorus diol rather than as a non-reactive filler. The product, 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide with CAS 99208-50-1, carries two phenolic hydroxyl groups with a hydroxyl equivalent weight of approximately 162 g/eq and a phosphorus content of 9.5 wt%. In a typical bisphenol-A diglycidyl ether/dicyandiamide varnish, DFM1721-A is pre-dissolved in methyl ethyl ketone at 50–60°C before the epoxy resin and accelerator are added. In a dicyandiamide-hardened system at 3.5 phr, DFM1721-A addition at 10–20 phr on epoxy resin solids supplies 0.06–0.12 equivalents of phenolic hydroxyl per 100 g epoxy resin and yields a calculated cured matrix phosphorus level of 0.8–1.6 wt%. The varnish is mixed in a high-shear dissolver at 500–1000 rpm, and the dissolved DFM1721-A is added slowly to prevent local precipitation. Varnish viscosity is maintained between 300 mPa·s and 700 mPa·s at 25°C on a Brookfield RVDV-II viscometer per ISO 2555. Glass fabric is impregnated on a horizontal treater with a B-stage window of 150–175°C and 3–7 min; residual solvent is kept below 1.0% according to IPC-TM-650 method 2.3.17.1. Lamination is carried out at 180–200°C under 20–35 bar for 60–90 min. The finished copper-clad laminate is tested to UL 94 vertical burn at 1.6 mm, thermal stress per IPC-TM-650 method 2.4.24.1, and copper peel strength per IPC-TM-650 method 2.4.8. Halogen content is controlled below 900 ppm chlorine and 900 ppm bromine by ion chromatography according to EN 14582:2016, with total halogens below 1500 ppm per IEC 61249-2-21. Compliance records include REACH EC 1907/2006 and RoHS Directive 2011/65/EU as amended by (EU) 2015/863. Because the phenolic hydroxyls participate in the epoxy cure network, press flow distance and B-stage conversion must be re-optimized whenever the DFM1721-A loading is increased. Published data for this exact formulation configuration is limited; a design-of-experiments study covering stoichiometric ratio, accelerator level, and treater speed is required for lot qualification.
| Property | Standard or test method | Acceptance window |
|---|---|---|
| Copper peel strength after thermal stress | IPC-TM-650 2.4.8 | ≥ 1.05 kN/m |
| Chlorine content | EN 14582:2016 | ≤ 900 ppm |
| Bromine content | EN 14582:2016 | ≤ 900 ppm |
| Total halogen content | IEC 61249-2-21 | ≤ 1500 ppm |
| Flammability | UL 94 | V-0 at 1.6 mm |
| Glass transition temperature drift versus control | ISO 11357-2:2020 | ΔTg ≤ 5°C |
Transfer-molded semiconductor packaging compounds are compounded on a two-roll mill at 95–110°C, well below the 245–252°C melting point of DFM1721-A. This mismatch creates the critical dispersion constraint. If the material is not pre-micronized to a D50 below 10 µm, residual crystals survive the mixing process and become stress concentrators in thin-wall packages. The mill gap is maintained between 0.5 mm and 2.0 mm, and the oil-heated rolls are monitored with an infrared pyrometer to avoid cold zones. The compound formulation is based on biphenyl epoxy resin and an o-cresol novolac hardener, with spherical silica filler at 82–88 wt% and DFM1721-A at 2–6 phr relative to the organic binder. At 4 phr addition, the phosphorus contribution to the filled compound remains low; therefore, DFM1721-A is normally combined with a DOPO-modified epoxy backbone or a nitrogen synergist to achieve UL 94 V-0 at 1.6 mm. After compounding, the cooled sheet is crushed and conditioned to 25°C before transfer molding at 175°C and 70–100 bar. Spiral flow is measured per ASTM D3123-15 at 175°C; the acceptance window is established by the package mold geometry and is typically monitored against the unfilled resin control. Cure kinetics are analyzed by differential scanning calorimetry per ISO 11357-2:2020; the onset temperature and conversion at 175°C are used to set transfer pressure and cure time. The finished package is subjected to moisture sensitivity level testing per J-STD-020E, thermal cycling per JESD22-A104, and flammability per UL 94. The principal process failure mode is wire sweep caused by high melt viscosity when the DFM1721-A particles are not fully dispersed; this is monitored by molding plasma-coated copper wire test chips and measuring wire sweep with scanning electron microscopy. Published quantitative rheological data for this exact biphenyl epoxy grade is limited, so mold flow simulation input must be validated against short-shot trials.
Because DFM1721-A contains two phenolic hydroxyl groups, its addition to styrene-based unsaturated polyester resin interferes with the standard methyl ethyl ketone peroxide/cobalt octoate cure system. Radical cure inhibition must be quantified by gel time profiling before the resin is released to a continuous laminator. DFM1721-A is pre-dissolved in styrene monomer at 35–40°C in a nitrogen-purged mix tank; if full dissolution is not reached, a polar co-solvent is introduced and then vacuum-stripped before part infeed. The monomer solution is added to the base resin at 3–8 phr. The free-radical inhibitor effect is compensated by increasing cobalt octoate from 0.2 phr to 0.3 phr or by raising the methyl ethyl ketone peroxide level while monitoring exotherm peak temperature. Gel time is determined per ASTM D2471; cure exotherm is measured according to the same method. The filled resin is processed by pultrusion or closed-mold infusion into flame-retardant cable trays and building panels. After molding, the composite is post-cured at 80°C for 2 h to complete conversion. Flame performance is assessed by cone calorimetry per ISO 5660-1 and by UL 94 vertical burn at 1.6 mm. The terminal product is a fiber-reinforced unsaturated polyester composite rated for low flame spread in transportation interiors per ISO 11925-2 ignitability testing. Published data for this specific configuration is limited; gel time shift must be re-established for each batch because the styrene concentration, inhibitor level, and DFM1721-A particle size interact.
High-pressure dispensing machines require that DFM1721-A be completely solvated in the polyol blend before the mix head. The diol is dissolved at 90–100°C into a branched polyether polyol under agitation; the solution is then cooled to 25–30°C and held until the viscosity stabilizes. At 8–12 wt% of the polyol blend, the viscosity change is recorded with a Brookfield RV viscometer per ISO 2555, and the polyol-side pump speed is adjusted accordingly. The isocyanate index is raised from 105 to 108–110 because the phenolic hydroxyls consume a portion of the MDI. Water is used as the blowing agent at 2.0–3.0 parts per hundred polyol. The mixture is dispensed through a high-pressure mix head at 120–150 bar and poured into panel molds. The cured rigid foam is tested for ignitability per ISO 11925-2, flammability per DIN 4102-1 Class B2 where required, and thermal conductivity per ISO 8301 to confirm that the flame retardant addition does not collapse the closed-cell structure. Closed-cell content is confirmed above 90% per ISO 4590, and core density is controlled between 45 kg/m³ and 60 kg/m³. Terminal application is halogen-free rigid polyurethane insulation board for building envelopes. The main processing conflict is pre-dissolution: if the solution is cooled too quickly, DFM1721-A recrystallizes and blocks the in-line filters; therefore, the mixing vessel is fitted with a heated recirculation loop and a 100 µm screen filter. Published data for this specific polyurethane formulation is limited; foam reactivity and cell morphology require pilot-scale evaluation on the target dispensing line.
DFM1721-A is incorporated into phenolic novolac hexamine molding compounds at 4–8 phr during roll mixing at 90–110°C. The molded commutator segments and appliance switch housings are evaluated to UL 94 and glow wire per IEC 60695-2-11. Published data for this specific configuration is limited; no bulk thermoset process change beyond roll-mill dispersion is advised without pilot trials.
Reactive extrusion trials with polybutylene terephthalate use a co-rotating twin-screw extruder with an L/D ratio of 40:1 and zone temperatures from 230°C to 250°C. DFM1721-A is added through a side feeder at 2–5 wt% to limit residence time and to avoid premature gelling from residual moisture. A vacuum vent is applied at zone 8 to remove volatile species. The degree of incorporation is monitored by melt flow rate per ISO 1133-1:2022 and by differential scanning calorimetry per ISO 11357-2:2020; a shift in crystallization temperature is used as an indicator of molecular weight modification. Molded connectors, relay housings, and low-voltage switchgear parts are tested to IEC 60695-2-12 glow wire at 750°C and to UL 94 vertical burn at 0.8 mm where customer specifications require V-0. Thermal stability is verified by thermogravimetric analysis per ISO 11358-1:2022; the 5% mass loss temperature and processing residence time are used to set the extruder profile. Capillary rheometry per ISO 11443 should be used to compare the melt viscosity curve before and after reactive extrusion. Published data for this specific configuration is limited; pilot compounding on the target twin-screw line is required because shear history, moisture level, and side-feeder screw design all affect the reaction extent.
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Sichuan EM Technology supplies DFM1721-A as a conformable single-sided electromagnetic interference shielding tape. The roll product combines a nickel–copper metallized woven polyester carrier with a halogen-free acrylic conductive pressure-sensitive adhesive and a silicone-coated polyester release liner. Supplier documentation lists a nominal total thickness of 0.085 mm excluding liner, with a slit tolerance of ±0.010 mm, and standard converted widths from 2 mm to 500 mm. The material is intended for low-profile grounding applications in portable display modules, notebook hinge assemblies, and internal enclosure seams where a continuous metal foil introduces excessive bending stiffness or die-cut edge burr. The product is supplied as log rolls and is most often converted by rotary die-cutting into discontinuous grounding pads, edge wraps, and seam bridges.
Shielding effectiveness in DFM1721-A is controlled by the in-plane conductivity of the metallized fabric, the through-plane conductive bridge of the adhesive, and the contact geometry at overlapping seams. The supplier reports surface resistivity no greater than 0.05 Ω/sq when conditioned at 23 ± 2 °C and 50 ± 10 % RH in accordance with ASTM D257. Insertion-loss screening under ASTM D4935-18 across 30 MHz to 1.5 GHz typically produces an attenuation envelope of 60–85 dB. The lower attenuation values appear near 30 MHz, where the periodic gaps between warp and weft yarns act as sub-wavelength apertures rather than as a continuous conductive sheet. In production, adhesive coating weight is held within ±5 % of nominal; a lower coating weight can shift surface resistivity upward by 10–15 %, while a higher coating weight can increase liner release above 25 g/in and slow adhesive transfer during die-cutting.
| Property | Nominal value | Reference method |
|---|---|---|
| Total thickness excluding liner | 0.085 mm ± 0.010 mm | ASTM D3652 |
| Surface resistivity | ≤ 0.05 Ω/sq | ASTM D257 |
| Peel adhesion to stainless steel | ≥ 1.2 N/25 mm | ASTM D3330/D3330M |
| Shielding effectiveness | 60–85 dB from 30 MHz to 1.5 GHz | ASTM D4935-18 |
| Service temperature | -40 °C to 105 °C | Supplier thermal endurance |
| Release liner | Silicone-coated polyester, 0.025 mm nominal | Supplier thickness gauge |
At the display module grounding station, die-cut DFM1721-A strips of 1.5 mm width are placed between the metalized frame and the ground pad of the driver flexible printed circuit. The formed bond path is expected to survive ±8 kV contact discharge under IEC 61000-4-2 without visible delamination extending more than 2 mm beyond the die-cut edge. In one high-volume tablet assembly line, adhesion loss after 72 h at 40 °C was traced to a release liner with aged release force above 30 g/in; the liner transferred poorly during vacuum pick-and-place and reduced pad placement yield. Restricting incoming liner release to 18 g/in or below corrected the fault. The tape is not intended to serve as a safety earth conductor and should not carry earth-leakage currents above 2 A.
Die-cut converters running DFM1721-A on a rotary platform should maintain die-to-anvil clearance at 0.025 mm. Excessive clearance produces hanging fiber ends at the die edge; insufficient clearance damages the release liner and causes transfer defects. Optical inspection of slit edges is recommended at 50× magnification to detect exposed monofilament ends greater than 0.5 mm. In slitting, a razor-blade converter should maintain blade angle at 20° to the web and replace blades every 50,000 linear meters to avoid serration of the fabric edge. Slitting speeds above 30 m/min without vacuum extraction can generate conductive lint that migrates onto adjacent adhesive surfaces. The lint is not apparent in unmagnified inspection but can defeat an IEC 61000-4-2 grounding pad by creating a high-resistance gap.
The pressure-sensitive adhesive used on DFM1721-A is a solvent-cast acrylic system filled with conductive particles. It is supplied as a halogen-free system according to IEC 61249-2-21, with combined chlorine and bromine below the 900 ppm reportable threshold. Peel strength to mirror-flat stainless steel is specified as no less than 1.2 N/25 mm when tested at a 300 mm/min crosshead speed under ASTM D3330/D3330M. On rough cast aluminium with Ra above 6.3 µm, peel retention falls to 60–75 % of the nominal value because the adhesive cannot fully wet the micro-roughness. The conductive filler system is incompatible with amine-based RTV silicones and sulfur-bearing EPDM; migratory species from these materials can oxidize the filler surfaces and increase through-plane resistance. Alcohol wiping of the mating surface before lamination removes die-release residues but does not compensate for insufficient surface smoothness.
During lamination, the adhesive is transferred at a nip pressure of 3–5 bar and a line speed not exceeding 12 m/min. Excess nip pressure compresses the woven carrier and flattens the conductive yarns, which reduces z-axis contact area at the adhesive interface. Incoming adhesive batches are tested for Brookfield viscosity at 25 °C using a #5 spindle at 20 rpm; a viscosity outside the 4,000–8,000 mPa·s window alters coat weight uniformity. Published data for DFM1721-A with a gravure-applied adhesive at speeds above 15 m/min is limited. Through-plane resistance is sensitive to the final lamination pressure used by the assembler. A hand roller applying less than 2 N force over a 1.5 mm wide strip may leave through-plane resistance above 0.5 Ω. Increasing pressure to 5 N over the same width decreases through-plane resistance to below 0.1 Ω because the conductive adhesive fillers improve contact with both mating surfaces. The lamination operation should be performed with a pneumatic press having a flat silicone pad of 80 Shore A hardness to avoid crease formation.
Replacement of a rolled copper foil with DFM1721-A changes both the electrical and mechanical response of the grounding joint. Copper foil offers lower sheet resistance and superior reflection above 1 GHz, but it tends to lift from curved display brackets unless the part is stress-relieved. DFM1721-A can be formed around a bend radius of 0.2 mm or less without carrier fracture and yields 10–15 % lower edge burr generation in rotary die-cutting. The woven carrier shears individual metallized fibers instead of slicing a continuous ductile metal film, which reduces conductive sliver contamination on converter cutting dies.
| Property | DFM1721-A | Copper foil tape | Conductive foam |
|---|---|---|---|
| Carrier | Nickel–copper woven polyester | Rolled or electrodeposited copper | Nickel-plated polyurethane foam |
| Surface resistivity | ≤ 0.05 Ω/sq | ≤ 0.005 Ω/sq | ≤ 0.08 Ω/sq |
| Shielding effectiveness | 60–85 dB (30 MHz–1.5 GHz) | 70–95 dB (30 MHz–1.5 GHz) | 50–90 dB depending on compression |
| Compression set | Not applicable | Not applicable | ≤ 15 % after 50,000 cycles |
| Die-cut edge sliver | Low | High | Medium to low |
| Temperature range | -40 °C to 105 °C | -40 °C to 120 °C | -20 °C to 85 °C |
For axial shielding of micro-coaxial bundles in notebook hinge applications, DFM1721-A is applied with a 50 % helical overlap. The overlap seam is burnished with a hard-rubber roller at 2.0–4.0 N linear force to seat the woven carrier into the adhesive. The resulting seam resistance is typically below 0.1 Ω when measured with a four-terminal milliohm meter. In one hinge qualification, through-plane resistance remained below 0.1 Ω after 10,000 actuation cycles. Because hinge geometry and clamp force vary between notebook platforms, published data for this exact configuration is limited and final qualification should be repeated on production hardware.
DFM1721-A roll logs are stable for 12 months from the date of manufacture when stored in original moisture-barrier packaging at 20–25 °C and 40–60 % RH. Refrigeration is unnecessary and can induce condensation at the adhesive–liner interface unless the roll is equilibrated for 4 h at ambient conditions before unwinding. Converting plants above 60 % RH should pre-dry rolls at 50 °C for 4 h and keep slitting-room humidity below 65 % RH. Moisture uptake in the woven polyester carrier can raise surface resistivity by 10–20 % because the yarns swell at interlacing points and open the conductive path. The change is reversible after re-drying but will cause false four-point probe rejection if not controlled.
Regulatory screening for the DFM1721-A product is reported against RoHS 2011/65/EU Annex II, REACH 1907/2006 SVHC Candidate List, and IEC 61249-2-21 halogen thresholds. The manufacturer’s lot certificate should be requested for each incoming batch because wet-chemical metallization of the fabric carrier can vary in residual bath species. The product should not be designated as the sole shielding element in millimetre-wave modules above 10 GHz; published data for attenuation in the 5–6 GHz WLAN band is limited, and the woven aperture geometry becomes progressively more significant as wavelength decreases.
