Foil Tapes Information
Foil tapes utilize a metal-foil backing which contributes to the tape's malleable, conductive, and rugged characteristics. This type of adhesive tape is properly employed in sealing, shielding, grounding, and resistance applications. Foil tapes cling to surfaces via a durable, pressure sensitive adhesive. These tapes find significance in the aerospace, metal finishing, appliance, and automotive industries.
Foil tapes are primarily for instances of electric or thermal conducting and shielding. Shielding tape with a conductive adhesive is used for electromagnetic interference shielding, grounding, and static charge. Foil tapes most commonly commission an acrylic adhesive that can be conductive or non-conductive. Their foil carriers offer UV protection, and are typically temperature resistant as well.
While foil tapes have most of the aforementioned qualities in common, the carrier material largely determines its undertaking. Carrier materials are recounted in the section below. Aluminum tape is common for HVAC sealing and repair, while copper tape is more appropriate for electrical shielding.
Foil Tape Production
Foil tapes are produced in a similar fashion as other adhesive tapes.
Electrically conductive adhesives typically suspend silver, graphite, or copper in the adhesive, and can be responsible for 80% of the adhesive's mass.
Acrylic - Acrylic-based adhesives reach their maximum adhesion almost immediately upon application, have adequate resistance, require no preparation, and have good sheer and peel strength. In foil tape applications, the acrylic adhesive can be made conductive and non-conductive.
Epoxy - Epoxy resins are adhesives that exhibit high strength and low shrinkage during curing. Epoxies are known for their toughness and resistance to chemical and environmental damage.
Pressure Sensitive - Pressure sensitive adhesives (PSAs) or contact adhesives are aggressively and permanently tacky at room temperature in dry (solvent free) form. They adhere firmly to a variety of dissimilar surfaces upon contact, requiring only the application of finger or hand pressure. PSAs do not require water, solvent or heat activation in order to exert a strong adhesive force on materials such as paper, plastic, glass, wood, cement and metal. PSAs have a sufficiently cohesive holding and elastic nature so that despite their aggressive tackiness they can be manipulated by hand and removed from smooth surfaces without leaving a residue. This is the most common adhesive of electrical tapes and as such, is not usually specified on product packaging.
Rubber - Adhesives with a rubber-based chemical structure have highly flexible bonds that are based on butadiene-styrene, butyl, polyisobutylene, or nitrile compounds. These rubber bonds should be resistant to deterioration in the presence of petroleum or other solvents.
Silicone - Silicone adhesives and sealants have a high degree of flexibility and very high temperature resistance (600°F). While available as a pressure sensitive application, some silicone adhesives may require ventilation, or UV or EB radiation to cure. Most notably, foil tape silicones can offer thermally-conductive silicone adhesives.
Foil Tape Carriers
Carriers are exclusively metal in material.
Aluminum - Aluminum carriers are a versatile foil tape carrier, and offers corrosion resistance, conductivity, durability, and reflectance.
Aluminum w/ Glass - Aluminum carriers with integral glass are used in high-temperature heat reflection, with additional tensile strength.
Lead - Lead carriers serve as a moisture and radiation barrier, as well as electric and thermal conductors.
Copper - Copper carriers find purpose in EMI/RFI interference applications, as well as in electrical bonding and component mounting instances. A brass carrier adds additional corrosion resistance.
Copper w/ tin plating - An additional tin plating to copper carriers facilitates soldering, and also resists oxidation and corrosion.
Steel - Steel backings provide a robust surface for aggressive adhesives. Steel foil tape retains its integrity in extreme temperatures and environments (nuclear, marine, aerospace). Stainless steel foil tapes are available.
|HVAC tape is a foil tape, typically aluminum in construction with an acrylic adhesive, that is explicitly meant to create air-tight seals in duct work and ventilation systems. This tape incorporates temperature resistance and a flexible bond. Closely related to HVAC tape is refrigeration tape, which holds a bond in very low temperatures.||
Image Credit: Lowe's
|Shielding tapes provide a conductive path or shield underlying data cables and devices from electromagnetic interference (EMI/RFI). Copper and aluminum foil tapes are commonly used for these applications.||
Image credit: Fox Electrical Supply
FSK system tape utilizes a cloth-strengthened foil carrier as a temperature-resistant vapor barrier. The tape conforms well to fibrous duct board and blankets.
Image credit: Venture Tape
For tapes, there are two important geometrical aspects to consider: width and thickness. Length is unimportant because this is determined by the user at the point of application.
- Width is the measurement across predetermined edges of the tape. Tapes can be cut by the customer to smaller widths.
- Thickness is the distance between the two, flattened surfaces of the tape (carrier and adhesive). It is usually expressed in mils or thousandths of an inch, and is measured under pressure with a gauge.
Other important specifications and features relate to the strength and resistance of the tapes.
- Tensile strength is the maximum load the tape can withstand. Foil tapes remain uncompromised in many extreme stress situations.
- Peel strength is the amount of force needed to separate two bonded surfaces. This is commonly rated in ounces per square inch to stainless steel. This is separate from the peel strength for the tape liner, which is considerably less.
- Temperature resistance is the amount of heat the tape can be subjected to without compromising the tape's performance. Foil tapes regularly exhibit temperature ranges between -35°F to 300°F.
- Abrasion resistance is the level of scratch resistance and ruggedness of the tape. Metalized backings provide durability, but may exhibit surface scratches.
- Once applied, products become permanently bonded to the substrate.
- Weather resistant products are suitable for outdoor use and are resistant to ultraviolet (UV) light, cold, heat, water or other weather conditions.
- The reflectivity of foil tape assists with its visual indentification as well as UV and heat reflection.
The most important standard in consideration of HVAC tapes is UL 181 A-P and UL 181 B-FX, covering the enclosure of fiberglass duct systems and flexible air ducts respectively. ASTM 2342 - 10 provides a test for assessing the durability of duct work sealants. ASTM D4935 - 10 provides a standardized test for measuring the EMI shielding effectiveness of planar materials. FSK tapes are explicitly controlled by ASTM C1136 - 10, a standard of flexible, low permeance vapor retarders for thermal insulation. Recall that manufacturers are not required to meet these minimum quality standards, but quality tapes will display a seal indicating standards to which they obeys.