The Characteristics and Uses of Adhesive Tape

Adhesive tape with high heat resistance

Dexerials produces and sells two types of adhesive tapes, each featuring two different types of adhesives applied to base materials such as cores and films.

Reworkable adhesives are designed to affix parts gently, which can be detached after adhesion. On the other hand, permanent adhesives secure parts with greater strength and are designed to prevent detachment after adhesion. (Trying to detach the parts may damage them.) Aside from adhesion strength, the following differences can also be seen between permanent and reworkable adhesives.

• The physical properties of reworkable adhesives do not change before and after the tape is affixed. Still, permanent adhesives harden from stimuli such as temperature, humidity, and UV light, leading to a change in physical properties (thus securing the adherend).
• Difference in freedom of adherend shapes: Reworkable adhesive tape is well-suited to attaching two smooth, flat surfaces. In contrast, permanent adhesive tape can attach adherents with some degree of unevenness and complex surface shapes.
• Permanent adhesive tape secures adherends securely, resulting in less deformation or misalignment when force is applied.
• Difference in heat resistance after adherence: Permanent adhesive tape maintains better adhesion at high temperatures in comparison to reworkable adhesive tape.
• Difference in storage temperature: With the exception of certain products, most thermo-curable permanent adhesive tapes harden at room temperature and therefore generally need to be kept in refrigerated storage. Reworkable adhesive tape, on the other hand, can be stored at room temperature.

The role of adhesive tape in flexible printed circuits

Of Dexerials products used in electronic devices, permanent adhesive tapes are often used in flexible printed circuits (FPCs). An FPC is a substrate with wiring for electronic circuits built onto an extremely thin film. The film can be bent freely, making FPCs an indispensable part of wiring in the movable parts of a mobile phone that is repeatedly opened and closed, or in the narrow housing of small electronic devices such as smartphones. Adhesive tape is used to secure stiffeners to the FPC as backing to attach parts such as ICs and LSIs. The stiffener makes it easier to mount parts to the FPC and also makes it easier to detach the substrate during product repairs, etc.

In addition, electrical conductivity is often added to the adhesive tape used in FPCs by mixing in a conductive filler. By using conductive adhesive tape to ground the metal backing material, such as stainless steel, to the substrate, it becomes possible to dissipate noise generated in the circuit.

A soldering process called reflow is needed to mount components to the FPC. In the reflow process, powdered solder is mixed with rosin, etc. to make solder paste and printed on the substrate in advance. After adding the components, it is passed through a reflow oven that reaches temperatures of up to approximately 260°C to melt the solder and assemble the components. The stiffener secured by adhesive tape is also heated to high temperatures during the process, and requires sufficient heat resistance.

Adhesive film that prevents dust from entering speakers

Dexerials has developed a way to apply its thermo-curable adhesive tape technology to thermo-curable (hot melt) dustproof nets to apply to various speakers. Speakers have small holes for sound transmission, but over time fine dust particles can enter through those holes and cause malfunctions. Our dustproof speaker nets use an electrostatic effect to prevent dust from entering without obstructing the speaker’s sound output by adhering a film with a finely meshed grid pattern.

This article touches on the characteristics and uses of adhesive tapes and adhesive films manufactured and sold by Dexerials. Permanent and reworkable adhesive tapes each have uses and applications in which they are well-suited, and detailed adjustments for each production step are necessary to ensure sufficient adhesion. Please do not hesitate to contact us for consultation if you are facing any challenges or questions regarding adhesion for electronic components.