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Pressure-sensitive adhesives (PSAs) join two similar or dissimilar components together, either temporarily or permanently. If that sounds like a vague description, it’s because these products manifest in several forms and serve various functions.

PSAs require no more than light to moderate pressure to initiate the bond. Some projects involving longer-term joining may need additional aid, like mechanical assistance from a press or higher-temperature process using an autoclave. In this blog, we’ll explore the topic in greater detail.

What Are Pressure-Sensitive Adhesives?

PSAs are available as pastes, tapes or films and can be made from cloth, plastic, paper, thin metal or other materials that form and cut easily. In addition to being easy to manipulate, PSAs save time and effort because they require no intervention to set the bond between components. Some PSAs require curing, but they don’t need water, solvents or other measures to create a bond.

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Pressure-sensitive adhesives (PSAs) join two similar or dissimilar components together, either temporarily or permanently. If that sounds like a vague description, it’s because these products manifest in several forms and serve various functions.

The first commercial PSA — a medical sticking plaster for protecting flesh wounds — was reportedly introduced in the U.S. in 1845. Most PSAs available today are water-based, but high-performance variants may still be solvent-based to provide superior shear strength and tack.

Like efforts to curb waste and pollution elsewhere in manufacturing and the built environment, work is underway to make PSAs more Earth-friendly. One promising development involves using soybean oil as a bio-based catalyst in next-generation PSAs instead of synthetic polymers.

How Do Pressure-Sensitive Adhesives Work?

Without getting into the chemistry weeds too deeply, PSAs contain polymers. Polymers are large molecules that assemble themselves fractally using smaller molecules (monomers). Polymers can be synthetic or naturally occurring, but their common characteristics are tackiness and viscoelasticity — or being viscous and impervious to permanent deformation.

Pressure-sensitive adhesives see wide use in the following industries and applications:

• Electronics: Bonding circuit layers together or improving PCB ruggedness;
• Structural: Attaching supports or stiffener components to products or parts;
• Labels and stickers: Temporary or permanent decorations and safety notices;
• Decals and laminates: Typically permanent and either decorative or protective; and
• Medical: Bandages and plasters for protecting wounds or holding them closed or protective coatings for medical devices and implants.

What Are the Advantages of Pressure-Sensitive Adhesives?

PSAs are a common sight in a variety of industries. But what precisely are the benefits of these products?

1. Wide Selection
PSAs are a mature product type with many distinct subtypes, each suited to a different specialization or industry application. Finding the right product will take some research, but it’s almost certainly out there.

2. Easy to Work With
Because they come in several forms and formulations, PSAs are extremely easy to work with. They’re available as liquid adhesives, films and curable pastes. Water-based PSAs are incredibly convenient because someone can remove them easily without damaging the product or component.

3. Chemical Resistance
Solvent-based PSAs are appreciated for their resistance to chemical interference and temperature extremes. This gives them relevance in a wide variety of applications and functional environments.

4. Support Variable Form Factors
The markets for consumer and industrial electronics are larger, more specialized and more diverse than ever. New technologies like IoT, 5G and AI require new form factors for hardware and related components. The easy application of PSAs supports this diverse range of hardware shapes and sizes, from implantable medical devices and smartwatches to embedded logic controllers in industrial equipment.

5. Compatible With Flexible Products
PSAs are compatible with next-generation designs like flexible printed circuit boards (PCBs), which aren’t always a good match for some conventional adhesives and joining techniques. PSAs can join the layers of a flexible-core PCB without adding too much bulk.

What Are the Types of Pressure-Sensitive Adhesives?

Although a wide variety of providers and products are available in this category, the vast majority fall within four broad classifications. Choose from the following depending on the product’s form factor, intended use and level of performance and other distinguishing characteristics.

Thermosetting Adhesive Films

Thermosetting PSA films arrive as rolls of flexible tape that is easy to manipulate, cut and shape. To install, the assembler simply applies light to moderate pressure to place the components. From there, an autoclave or press will apply additional force or heat to set the bond between the parts fully. These are used frequently in circuit assembly.

Liquid Adhesives

Liquid adhesives are available as one-part epoxies or two-part epoxies. These products provide some of the most secure joining capabilities of any pressure-sensitive adhesive. The downside is they can be demanding to apply cleanly and evenly. They’re the best choice for specific niche applications, like reducing pressure on the edges of a printed circuit board.

Thermoplastic Adhesive Films

Thermoplastic adhesive films are popular for several practical reasons. They arrive polymerized, so there’s no time-consuming or costly process to finalize the bond. Additionally, they’re substantially easier to work with than most other PSA products, so they’re the best choice in cases where repairs or troubleshooting may be frequent.

Curable Adhesive Pastes

Curable adhesives require brief exposure to ultraviolet (UV) light to create a cured and permanent bond. The curing process is essentially instant, eliminating adhesive dripping or moving about during handling and processing. These characteristics make curable adhesives great for strain relief, wire management and ruggedization.

Pressure-Sensitive Adhesives, Demystified

Pressure-sensitive adhesives are small components with prominent roles to play across disciplines and industries, no matter the type of manufacturing involved. Their potential uses throughout almost any sector allow for enhanced creativity and efficiency.

ABOUT THE THE BLOGGER Emily Newton Emily Newton is the Editor-in-Chief of Revolutionized, a magazine exploring innovations in science and industry that shares ideas to promote a better tomorrow. She regularly covers trends in the industrial sector. In addition to her work with Revolutionized, Newton is also a contributing author for loT Times and the International Society of Automation. Newton also provides science and tech insights at BBN Times. For more information please visit connect with Newton on LinkedIn or contact her at https://emilyjnewton.com/. SEE ALL CONTENT FROM THIS CONTRIBUTOR