DSM polyamide used for smartphone structure

A China-based smartphone producer has chosen Stanyl ForTii, a high-performance polyamide from DSM for its latest design.

Xiaomi Technology Co., Ltd is using the material for the frame spitters of its ‘Xiaomi Mi4’ model, where aesthetics, mechanical performance, high flowability, colour stability and chemical resistance are key to its suitability for what is a significant part of the phone. 

Metal frame design is currently an important feature for an appealing and rugged high-end smartphone. The technique to achieve reliable transmission and receipt of antenna signals in conjunction with aesthetic design is a challenge, says Xiaomi.

Insulative antenna splitters have turned out to be an effective solution and the frame splitter is an exterior part of the Smartphone. The selected material not only has to meet the mechanical requirements of the mobile structure, but also has to perform excellent flow and colour stability under high-temperature and chemical processing.

Challenges to material

Coming with a metal frame, the applications and procedures for making a frame splitter of Xiaomi Mi4 have to meet a number of performance requirements.

 As both metallic ends of the frame need to be electrically disconnected, a plastic frame splitter is used to mechanically connect them. The strength and tenacity of the plastic itself are very demanding, therefore it is required to be resistant to constant pulling and falling.

In addition, the frame splitter and metal frame are attached to each other. To perform the insert moulding process, an extremely high flowability is required for the material.

As the frame splitter is an exterior part, there is also a very high demand on aesthetics, colour in particular. The final part has to undergo 80˚C-100˚C high-temperature procedures and cleaning processes in strong alkaline solution, therefore demanding high requirements on colour consistency and retention of mechanics

After processing, the part needs to be precision machined and the material needs to be immersed in cutting fluids. It must be corrosion resistant.