Cell phones take a break from the heat

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Making videos, posting photos, online shopping, chatting with friends. Maybe even making a phone call ... Smartphones are high-tech devices. However, plenty of electronics in a small space also means that cell phones are under heat stress – around the clock. To ensure continued functionality, extremely thin special adhesive tapes play a double role: They connect components to one another and provide thermal management. That's kind of cool.

There's a clear trend: Smartphones, tablets, smartwatches & Co. are becoming ever more powerful with every new device generation. But together with faster computing processors, more brilliant displays and more durable batteries, the potential heat development also increases. And the smaller the device, the stronger the heat. Elevated external temperatures or direct sunlight swiftly add additional heat, thus, raising the temperature to 70 or even 90 degrees. Ergo, cell phone manufacturers have to come up with some cool ideas for thermal management to allow mobile all-rounders to work reliably and to protect their valuable "inner workings" from damage. 

Thermal management in cell phone housings

The core of thermal management is the cooling system that works in the background while users raise the temperature in their smart companions. Due to the small volume of smartphones and tablets, however, active cooling technologies such as fans or electrothermal Peltier elements are not an option. Therefore, passive heat dissipation is the preferred physical principle in cooling systems. Different technologies are taken into consideration: Heat Sinks – these are heat conductors with a large surface, for example, made of aluminum; Heat Spreaders – such as thin sheet metal made of copper or aluminum; or Heat Pipes – closed, thin-walled pipes made of thermally highly conductive material, filled with vaporizable liquid, such as water. 

Double-sided tapes for heat dissipation

What every cooling system needs are "bridges" to remove the heat loss, so-called Thermal Interface Materials (TIMs). In addition to other materials, special adhesive tapes from tesa (so-called Thermal Management Tapes TMT) are also used for this purpose. The advantage: On the one hand, they ensure that the components inside smartphones are firmly held together. On the other hand, they close gaps and eliminate air pockets. This is important because air, being a poor heat conductor, increases the risk of heat build-up. 

tesa TMT Cooling Scenario

With its various adhesive tape applications, tesa has been a popular supplier to the global electronics industry for many years – up to 70 tesa tapes may find space in a smartphone. The products suitable for heat dissipation are constantly being further developed. "We use double-sided adhesive tapes and enrich them with ceramic particles. And they are no thicker than an average human hair," explains Minyoung Bai. He works for tesa Electronics in South Korea and, as head of the laboratory for conductive tapes, is the company's expert. 

"We use double-sided adhesive tapes and enrich them with ceramic particles. And they are no thicker than an average human hair."

Minyoung Bai

Lab Manager R&D, BU Electronics

TMT Product

Product development on three continents

The global device manufacturers and their suppliers ensure that Bai and many of his colleagues in product and technology development continue to have sufficient "operating temperature": They are demanding ever thinner tapes with ever more additional functions or benefits. Ultimately, efficient heat routes in smartphones are one of the major challenges, as lab manager Bai emphasizes: "To conduct the heat more quickly through the adhesive tape, we can use two big levers in product development: We can either increase the thermal conductivity or make the tapes thinner."

"We see ourselves as a technology partner for our customers."

Carsten Meyer-Rackwitz

Head of tesa Electronics division

Carsten Meyer-Rackwitz
Carsten Meyer-Rackwitz underlines the advantages of Thermal Interface Materials (TIMs)

A task that tesa tackles confidently, thanks to decades of expertise: "We see ourselves as a technology partner for our customers. With our development centers in Germany, China, USA and since last year also South Korea, we can react quickly to new requirements and develop innovative adhesive solutions in close cooperation with our customers," says Carsten Meyer-Rackwitz, head of the tesa Electronics division. There is no need to worry about the growth potential in the still young market of thermally conductive tapes: Elevated adhesive strength and thermal conductivity, extremely thin and smooth adhesive layers, and simple and clean fitting make tesa tapes a combination that global players can literally count on. 

Smartphones

Around three billion people worldwide use a smartphone – and the numbers are rising. Up to 200 adhesive tapes are used to assemble components for the mobile all-rounder. tesa delivers approximately 70 adhesive tapes for various applications, including the transparent bonding of individual layers in displays, electrically conductive, radiation-reducing adhesive tapes, or tapes for mounting batteries. Their thickness varies between 5 and 500 micrometers (µm), the equivalent of 0.005 to 0.5 millimeters. Advantages of adhesive tapes: They save weight and space and are quick and easy to use in production. Some of the tapes used are also suitable for heat dissipation (Thermal Interface Materials). 

Mobile Phones

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