Saint-Gobain CHR SG56-05(R) is a pressure-sensitive tape constructed with a woven-glass fabric backing that is saturated with polytetrafluoroethylene and modified at the release surface for static dissipation. A silicone pressure-sensitive adhesive is applied to the reverse face. The product is supplied in a total thickness class of 0.005 in (0.127 mm), with standard slitting widths available from converting sources between 12.7 mm and 914.4 mm. The (R) designation in supplier literature identifies the anti-static backing treatment rather than a packaging revision. Continuous service temperature for the silicone adhesive is published from −73 °C to 260 °C; however, the actual adhesive bond-line temperature should be measured with a contact thermocouple because the low thermal conductivity of the glass-PTFE composite can produce a measurable gradient between the exposed release face and the substrate.

The tape is used where a non-stick release layer must also prevent charge accumulation on thin polymer films during heat sealing or high-speed web transport. Unmodified PTFE/glass tapes are electrically insulating, with surface resistivity commonly above 1 × 10^13 Ω/sq, and can develop triboelectric potentials during roll unwinding or separation from molten polyolefin. The SG56-05(R) construction reduces surface resistivity into the static-dissipative range, typically 1 × 10^5 Ω/sq through 1 × 10^9 Ω/sq when measured under ASTM D257 at 50 % RH. That resistance measurement alone does not constitute full ESD qualification; charge decay time, grounding path, and relative humidity must be evaluated for the specific machine geometry.

Material stack-up, dimensional architecture, and backing configuration

The backing combines the tear resistance of woven glass fiber with the low surface energy of PTFE. The glass fabric is saturated and coated with PTFE rather than laminated to an unsupported film, which improves puncture resistance and allows the composite to survive repeated jaw cycling without splitting. Thickness is measured under ASTM D3652/D3652M; the nominal total thickness is 0.005 in, with backing and adhesive contributions reported separately on the supplier data sheet. Tensile properties for glass-PTFE backing of this class are commonly determined by ASTM D3759/D3759M and typically show elongation at break below 5 %. Supplier documentation describes the anti-static treatment as integral to the fluoropolymer surface rather than as a loosely bound carbon topcoat; nevertheless, surface resistivity should be rechecked after solvent wiping or abrasive cleaning because either operation can damage the dissipative layer.

Mechanical behavior is anisotropic because the woven glass fabric has different fiber counts in the warp and fill directions. The higher-strength axis should be aligned with the machine direction on heat-seal jaws. Converting is performed with hard-metal or ceramic rotary slitting blades; razor-blade slitting can fracture glass fibers and produce a rough edge that lifts during jaw release. The silicone adhesive is pressure-sensitive and sufficiently conformable to wet stainless-steel and chromed jaw surfaces, but initial tack at room temperature is lower than that of an aggressive acrylic transfer adhesive. That tradeoff is accepted because silicone retains useful debond characteristics at temperatures where acrylic adhesives soften and leave residue.

Because surface resistivity is measured according to ASTM D257, the result depends on electrode geometry, applied voltage, and conditioning time. A single resistance reading is not a complete ESD control plan. ANSI/ESD S20.20 and IEC 61340-5-1 classify static-dissipative surfaces below 1 × 10^9 Ω/sq, but the tape must be connected to earth through the sealing bar, idler roller, or a dedicated grounding clip. If the silicone adhesive acts as an insulating barrier between the anti-static backing and the grounded metal jaw, charge will not drain reliably; a conductive adhesive transfer tape or an additional bonding path is required in that configuration. Relative humidity strongly affects anti-static fluoropolymers. At 12 % RH and below, surface resistivity can increase by orders of magnitude and charge decay time can rise. Qualification should include measurement at the low-humidity winter line condition rather than only at 50 % RH laboratory conditioning.

Charge decay is a separate measurement from resistance. A backing with surface resistivity below 1 × 10^9 Ω/sq can still show a finite decay time from 5,000 V to 500 V, depending on the capacitance of the backing and the grounding path. A common production failure is the use of a clean ceramic or anodized jaw that does not conduct the backing charge to ground. The tape should be inspected at installation for grounding contact between the roll edge and the metal jaw; a small stainless-steel toe clamp is sufficient provided it contacts the anti-static backing rather than the adhesive side.

What distinguishes the anti-static PTFE/glass backing from conventional PTFE-glass tapes?

Conventional PTFE/glass tapes are used for release and thermal protection, but their surface is insulating and can accumulate charge when the liner is removed or when the tape is exposed to fast-moving polymer web. In dry packaging rooms, unwinding an insulating release tape can produce surface potentials above 1 kV, which exceeds the withstand limit for many semiconductor devices handled under ANSI/ESD S20.20. The SG56-05(R) anti-static surface reduces the potential-generation rate and drains residual charge to the sealing-bar ground; it does not eliminate the cleanliness and grounding controls required for static-sensitive components.

The silicone adhesive also separates this product from PTFE/glass tapes using acrylic adhesive systems. Acrylic pressure-sensitive adhesives typically soften above 149 °C; silicone pressure-sensitive adhesives sustain continuous service near 260 °C and can tolerate short dwells at higher sealing-bar setpoints. The difference is significant in impulse sealers where the surface temperature can overshoot the setpoint during a 0.5 s to 3.5 s dwell. In such equipment, an acrylic adhesive may creep, transfer, or char, while the silicone adhesive retains position. However, silicone adhesives generally have lower room-temperature peel strength than acrylic systems on low-energy films such as untreated polyethylene; bond validation on the actual jaw surface is therefore required.

The anti-static designation should not be confused with a conductive-adhesive grounding tape. A fully conductive tape would exhibit surface resistivity below 1 × 10^5 Ω/sq and may be specified when the sealing jaw itself is not grounded. The SG56-05(R) dissipative range is optimized for charge drainage without significantly reducing the non-stick release function. Carbon-loaded conductive PTFE tapes often show higher release force, which can increase seal-area film distortion or translucency in thin-gauge packaging.

Compared with unsupported skived PTFE film tapes, the glass-reinforced backing has lower elongation and higher tensile strength but is thicker and less conformable. On flat sealing bars this dimensional rigidity is beneficial. On convoluted surfaces or radiused corners, the glass weave can produce wrinkle paths and local lift. When the sealing jaw contains curved induction elements, the tape should be pre-tensioned during installation to prevent bridging at the concave radius; overtensioning can introduce shear stress that accelerates adhesive creep at temperature.

In rotary band sealers, vertical form-fill-seal jaws, and L-bar sealers, the tape is applied to the heated sealing face to prevent molten polyethylene, ionomer, or sealing lacquers from bonding to the metal. The PTFE surface releases the seal area while the glass fabric prevents the tape from splitting under the shear imposed during jaw separation. Edge lift at the jaw clamp is the most common failure mode because the adhesive there is loaded in peel rather than shear. The tape should be replaced at the first sign of edge lift, because an exposed adhesive edge can transfer silicone to the package film and produce a visible seal defect. For form-fill-seal tooling with curved jaw surfaces, the tape is pre-tensioned during installation to avoid bridging at the concave radius; overtensioning can introduce shear stress that accelerates adhesive creep at temperature.

Because the backing contains glass fiber, slitting and die-cutting create free glass filament ends at the cut boundary. In electronics manufacturing, these filaments can detach from the edge and become conductive particulate contamination. Slitting should be performed with vacuum extraction, and slit edges should be inspected under low magnification for fiber bloom before the roll enters the cleanroom. If the tape is to be kiss-cut for automated jaw placement, a PTFE-coated liner may be specified to prevent silicone adhesive transfer to the cutting die.

When anti-static performance must be preserved through repeated heat-seal cycling

After repeated cycling, the anti-static PTFE surface can change through oxidation, wear, or contaminant transfer from the sealed film. The acceptable service interval is defined by two independent limits: release failure and electrostatic failure. Release failure appears as film tearing or seal-area adhesion; electrostatic failure appears as surface resistivity above 1 × 10^9 Ω/sq or charge decay times outside the process allowance. Both limits should be tested on a representative tape coupon removed from the jaw, because the exposed surface on the machine is contaminated by sealant additives, processing waxes, or starch that are not present on a new roll.

Silicone pressure-sensitive adhesives undergo additional crosslinking during high-temperature aging, which can reduce room-temperature peel adhesion under ASTM D3330/D3330M while bond strength at operating temperature remains acceptable. Hot peel or hot shear measurement at the actual jaw setpoint is more relevant than ambient peel alone. Published data for SG56-05(R) after 1,000 heat-seal cycles on a specific resin are limited; end users should generate statistical qualification data for their film stock, temperature profile, and line speed rather than rely on a single supplier-listed peel value. Batch-to-batch variance in adhesive coat weight is a known source of ambient peel variation; incoming lots should be compared with the previous accepted lot under ASTM D3330/D3330M.

Compliance and test-method matrix for antistatic tape qualification

Incoming material control is typically organized around the following matrix. The table lists the standard methods used for property verification; acceptance limits are taken from the manufacturer’s certificate of analysis where available, because some lot-specific values are not fixed by industry standard.

RoHS and REACH documentation should be requested for the specific stock-keeping unit; the anti-static additive can change the declarable substance list compared with non-anti-static PTFE/glass tapes. RoHS 2011/65/EU and REACH EC 1907/2006 declarations are regulatory rather than performance documents. If the tape will be used in food-contact sealing, verification of backing and adhesive compliance under FDA 21 CFR 177.1550 or EC 1935/2004 is required; industrial grades are not automatically food-contact compliant.

The tape is not intended as primary electrical insulation. Dielectric breakdown values provided under ASTM D149 are for film/backing quality control and do not establish creepage or clearance safety barriers. Silicone adhesives can release volatile siloxanes above 150 °C; in cleanrooms used for optical coating or semiconductor lithography, outgassing screening under ASTM E595 or a customer-specific thermal desorption method may be required. Storage before use should be in horizontal rolls at 21 °C ± 3 °C and 45 %–55 % RH, enclosed in polyethylene packaging to limit moisture uptake and plasticizer contact. Avoid exposure to esters, aromatic hydrocarbons, and chlorinated solvents because these swell the silicone PSA and change unwind performance.

In ESD-protected packaging areas, the tape is frequently installed on heat-seal bars operating at 190 °C to 220 °C with dwell times from 0.5 s to 3.5 s. The anti-static PTFE/glass surface reduces charge transferred to cover tape after seal separation, provided the backing is grounded directly to the jaw. If grounding is interrupted, the dissipative layer cannot drain charge and the packaging line can show residual potentials on formed trays. Under those conditions, the tape’s surface resistivity measurement is not sufficient; the complete jaw assembly must be tested with a grounded operator and charge plate monitor or field meter according to the facility ESD-control plan.