In the past, the only way to join materials was with either mechanical fasteners or liquid glue. These products served the purpose at the time, but assembly was a long, labor-intensive process. Then, in 1845, Dr. Horace Day developed the first pressure-sensitive adhesive. He applied the adhesive to fabric and used it as a surgical plaster.
Over the years, engineers and scientists have built on the uses for pressure-sensitive adhesives and ultimately found many benefits useful for assembling parts and materials. Today pressure-sensitive tapes are used every day in applications from office tape to highly specialized applications like electronics.
The use of pressure-sensitive tapes for assembly applications provide both production efficiency and reduced labor costs. Other benefits include the ability to easily bond various materials – including lamination of flexible materials – and the ability to make products thinner and lighter.
Today’s variety of assembly applications often require pressure-sensitive adhesive tapes with specialized, high-performance properties. Adhesives have been developed to perform in applications requiring high or low temperature performance, chemical resistance, insulation properties, clean removability, resistance to extreme weather, long-term performance, the ability to bond to rough or uneven surfaces, skin sensitive applications and the ability to bond to low energy surfaces like polyethylene or silicone. When combined with other components or backings, performance properties can include cushioning, sound insulating, electrical dissipation, surface protection, gasketing, medical device suitability, or reliable performance as an assembly aid in a continuous production process. Of course, there are many more uses, but this gives you pretty good idea of the wide variety of applications and specialized tapes that are available.
So, great, I’ve listed all of these properties and potential performance requirements, but where and why would these be needed? Here are a few examples to help you better understand why there are so many different tapes:
One great example is the touch screen on your cell phone. There are layers of various pressure sensitive coated films used in the assembly of the phone. One layer might hold the glass screen in place but also provide an anti-shatter property if the glass screen were to break. In this application, the tape needs to have clarity and be strong enough to hold the glass together if broken. The tape will also need to be able to withstand temperature fluctuations, perform for years, not react or fog the phone’s screen and not interfere with electrical components. Another layer might be needed to protect the phone from electrical interference, EMI. By dissipating the EMI, the electrical components will continue to function properly.
Another application requiring a highly specialized double sided tape is lens grinding and polishing. A lens is generally made of glass, although eyeglasses can be polycarbonate. In order to perform, the glass needs to be ground and polished. This process involves an abrasive disc rotating in a liquid slurry. The specialty double-coated tape must hold the abrasive disc to a steel platen while rotating. It also has to be able to perform for hours while submersed in the slurry. At the end of the polishing process, the tape is removed from the platen. It must remove cleanly without leaving any residue on the platen. Therefore this application requires a special tape that provides all of these special properties.
Here’s one that appears to be more simple: a label. Specifically, a label that is applied on a bullet proof vest. The materials of each vest must be traceable for years and years, up to 50 years or more. The label is critical should a recall or quality check of the specific product be needed. Here, the label must have a strong bond to the outer vest material for a long time and it must not be able to be removed. It needs to have resistance to environmental conditions, abrasion, and movement. It also has to be flexible and able to be ink receptive and non-smudging.
I hope that this article has been helpful in understanding how pressure-sensitive tapes have become popular and critical in some assembly applications.