Silicone and Acrylic adhesive applied polyimide films are used for various coil wrappings including Tesla Coils, gold-finger masking, high-temperature masking, splicing, temporary bonding of thermocouples for oven profiling, insulating circuit boards, and other applications that require both the properties of the polyimide film as well as the adhesive properties provided by either silicone or acrylic.

CAPLINQ also offers non-adhesive polyimide film (PITN-Series). This product has been successfully tested as a release film in a welding press that fuses PTFE-coated (Teflon-coated) composite conveyor belting (made of glass-fabric). This process previously used a silicone impregnated glass, but some customers do not like the silicone release cloth burn-off and therefore this alternative method, using adhesive-free polyimide film was developed.

For more information of copper wire bonding, visit us or contact us for more details.

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This CFTA tape is being developed for one of CAPLINQ’s customers that requested it for EMI shielding. Other thicknesses of electrolytic copper foil will eventually include:
-9um
-10um
-18um
-25um
-70um
-105um

These foils are use in the following industries: printed circuit boards (PCB), CCL, EMI, Lithium Battery & Polymer Lithium Battery.

The price of these foils has not yet been announced, but stay tuned, visit us or contact us for more details.

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Silicone-based adhesives are certainly more standard, but sometimes the customer needs acrylic because they cannot have silicone in their systems, need higher adhesion at mid-range temperatures or other specific reasons.

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The Usual Suspects

Generally speaking, manufacturers use three different adhesive types in combination with the backing material to produce a final “tape” product. Though these adhesive types can be subdivided into subgroups, the main categories are as follows:

1. Silicone
2. Acrylic
3. Rubber

Each of these adhesive types have advantages and disadvantages which make them more or less suitable for particular applications. Here we will draw the major lines outlining these differences.

Silicone adhesives

Silicones have been used to formulate adhesive products for decades due to their flexibility, temperature cycling resistance, chemical resistance, and wide range of possible material properties.

Silicone adhesives have the following general characteristics:

• High flexibility (low modulus) at sub-ambient temperature
• Consistent performance over wide temperature range (a reason they work so well with Polyimide Tapes)
• Excellent ageing and UV resistance (a reason they work so well in LED applications)
• High temperature resistance
• Good resistance to polar solvents

Compared to acrylic and rubber adhesives, they are significantly more expensive, but due to their excellent high temperature performance they are very well suited to splicing tapes, masking tapes and polyimide (Kapton) tapes.

Acrylic Adhesives

Acrylic adhesives can either be water-based (this is also referred to as emulsion or dispersion) or solvent-based. Water-based are slower drying compared to solvent-based systems but generally solvent-based acrylic systems have better resistance to other solvents, chemicals and water. Comparatively, water-based systems are less expensive than their solvent-based counter parts.

Acrylic adhesives are generally divided into two subgroups: Pure and Modified

Pure acrylic
Pure acrylic adhesives share the following characteristics:

• Reasonable adhesion to a wide range of substrates (see modified acrylics below)
• Good ageing, transmittance and UV resistance (a reason they are often used in fiberoptic applications
• Reasonable temperature resistance; between silicones (high resistance) and rubber (low resistance)

Pure acrylics have a lower tack (“stickyness when dry” for the layman) and less adhesion on hard-to-bond plastics such as high- and low-density polyethylene (HDPE & LDPE) and polypropylene (PP) than modified acrylic or rubber adhesives. Pure acrylic adhesives are mainly used on tapes whose applications are bonding, sealing or surface protection.

Modified acrylic
For all intents and purposes, modified acrylics have the same characteristics as pure acrylics, but have superior adhesion to the hard-to-bond-plastics mentioned above. Generally, these are more expensive than pure acrylics and are used for plastic bonding (including vinyl and linoleum), lamination and splicing.

Rubber Adhesives

Just from looking at the roll, it is very hard to tell what type of rubber is used on the tape. Look at the figure to the right, and this same picture can be used to describe every type of rubber-tape below. The key is to ask the supplier what type of rubber adhesive is used. Like acrylics, rubber adhesives can be divided into two subgroups: Natural and Synthetic

Natural rubber
These adhesive have higher tack (again “stickyness when dry” for the layman) than acrylic adhesives as well as higher shear strength but they have limited UV resistance. These are used in the cheapest tapes on the market, but have limited applications. Natural rubber adhesives are used in duct tapes, low-temperature masking tapes and surface protection tapes (think of the tape you get on your new fridge or stove).

Synthetic rubber
As the name implies, synthetic rubber is “formulated rubber” – think coming from the lab, not coming from the tree. Synthetic rubber can broken into three subgroups: Hot-melt, Solvent and Butyl rubber.

Hot-melt rubber

Hot-melt is a low-temperature melting plastic, which makes this adhesive have low temperature resistance. It also ages poorly (becoming brittle) and has low UV resistance. This rubber is used for low- to medium-duty carton sealing, low-temperature splicing as well as paper core starting applications.

Solvent rubber

Solvent-rubber based adhesives have better temperature and aging performance but still poor UV resistance. It is used for electrical and foam tapes.

Butyl rubber

Butyl rubber based tapes have excellent UV and aging resistance but lower mechanical strength. These tapes are used in foam tape applications and construction and plumbing applications such as pipe joints.

Visit CAPLINQ.com today or ask us how we can help you select the right tape for your application.
tapes are mainly used for sealing applications in the building and construction industry. T

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Polyimide Tape is made up of two separate steps. First is the manufacture of the polyimide film itself and the second is the application of the adhesive backing.

The Polyimide Film Manufacturing Process

Polyimide film, the generic name of of DuPont’s tradename Kapton®, is synthesized by polymerizing PMDA and ODA in strong polar solvents through the process of forming film and imine treatment at high temperature. This synthesis creates excellent physical, chemical, and electrical properties, as well as atomic radiation resistance, solvent resistance and low & high temperature resistance. It performs well in a wide range of temperatures as low as -452°F (-269°C) and as high as +500°F(+260°). Because of these characteristics, it is uniquely suitable for specific for many high temperature applications.

Manufacturing Polyimide Silicone PSA Tapes

Polyimide Silicone Adhesive Tape is made by first taking polyimide film and coating it with a heat-resistant silicone adhesive. Due to its stable pressure-sensitive macromolecule adhesive layer at high temperature, the tape offers excellent properties of heat resistance, electrical insulation, solvent resistance and radiation protection. Being silicone, it offers better elongation at break, and is used for electrical insulation of electrical equipment and high temperature insulation. It offers the highest heat resistance among film adhesive tapes, so it can also be applied for insulation in high-end electronic equipment, motors, and Lithium (Li) batteries. Other applications include the protection of the gold fingers on Printed Circuit Boards (PCBs) during wave soldering, as lead-free solders often require reflow temperatures up to 260°C – an operating temperature for which polyimide tape is uniquely suited – leaving no adhesive film once the tape is removed. Finally (though the true list of applications is nearly endless), it can be used for shielding in high temperature applications.

Manufacturing Polyimide Acrylic PSA Tapes

Polyimide Acrylic Tape is made using the same process as the silicone process described above, but though the acrylic is typically a heat-resistant acrylic, it still cannot withstand the high temperature range of the silicone PSA described above. Also, acrylics tend to be more brittle, so the lower temperature range is also somewhat more limited as the adhesive can crack at extremely low temperatures. However, since the polyimide acrylic tape still uses a base of polyimide, the film itself is still able to withstand a wide temperature range and can still be used in many of the same high-temperature applications; it is just that the adhesion properties of the film become more limited with an acrylic adhesive. Acrylic chemistries are typically cheaper materials also, so the final selling price of acrylic-based polyimide tapes are generally lower.  Though CAPLINQ offers both acrylic-based and silicone-based tapes; given the marginal price difference and the wider range of applications, the most popular tapes remain the silicone-based polyimide tapes.

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