Component Management

Liquid pressure-sensitive adhesives for electronics

9th December 2020
Alex Lynn

DELO has developed two liquid pressure-sensitive adhesives that have similar properties to (double-sided) adhesive tapes, but are applied in liquid form. DELO PHOTOBOND PS4130 and DELO KATIOBOND PS6372 can be dispensed easily and join components accurately with pressure.

Components can then be handled immediately in a fully automated process, saving time and money during production. Well suited for electronic applications, like smartphone speakers or display frames these liquid pressure-sensitive adhesives open up new possibilities in a variety of markets.

Adhesive tapes vs liquid pressure sensitive adhesives

Adhesive tapes are used in a variety of bonding applications in the electronics industry. Their advantage is the immediate adhesion after two components have been pressed together. However, adhesive tapes have two major disadvantages.

The first is when using small or complex tape geometries, automated handling becomes very time-consuming or even impossible due to the low stiffness of the carrier material and the high adhesive force. The second is that structures with a low fill factor, like those found in frame bonding, involve a large amount of waste from cutting the geometric shapes. This increases component costs.

DELO’s liquid pressure-sensitive adhesives offer an advantage over tapes because they are dispensed in liquid form directly onto the component and then irradiated by UV light. This creates a tacky surface, like tape. Since the adhesive reaches its initial strength immediately after the second component is pressed on, the bonded assembly can be processed directly and without any fixing devices. This is a great advantage over many standard liquid adhesives.

The entire process, from precise dispensing even on tiny components or three-dimensional geometries to irradiation and mechanical pressing, can be fully automated. This makes the liquid pressure-sensitive adhesives particularly suitable for high-output production.

Depending on the requirements, users can choose liquid pressure-sensitive adhesives with different chemical bases. The acrylate based adhesive DELO PHOTOBOND PS4130 has very similar properties to typical adhesive tape in terms of flexibility, peel resistance and strength. It is particularly suitable for adhesive applications with short cycle times and moderate requirements on final strength. Thanks to its excellent damping properties and low outgassing values, DELO PHOTOBOND PS4130 is already being used in things like the assembly of smartphone speakers.

The epoxy based adhesive DELO KATIOBOND PS6372 was developed specifically for structural bonding applications requiring high strength. Once the initial strength has been achieved by pressing on the components, the assembly can be processed immediately, with the strength of the bonded joint increasing afterwards. When fully cured, DELO KATIOBOND PS6372 achieves compression shear strengths of over 30MPa on aluminium and over 10MPa on FR4. Its high resistance to temperature and media makes it suitable for automotive applications.

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