Smartphone Materials Q&A with OnePlus' COO & Head of R&D

Product 2021-09-27
OnePlus is known for the best hardware coupled with the best software to drive a burdenless experience for our users. However, hardware doesn’t only mean the best SoC or the biggest battery, it also means the materials used in the development of a device. Throughout our history we have explored and used a range of materials within our products from stainless steel to sapphire to glass to ceramic and more, so we wanted to get insight from OnePlus’ COO and Head of R&D, Kinder Liu, on the range of materials used within consumer devices and how OnePlus continues to evaluate them.

1. Sapphire screen phones have been around off and on for a decade, but they’ve never really taken hold, and most companies don’t offer them — why is that?

Sapphire crystal displays are highly scratch resistant and extremely tough compared to traditional, chemically enhanced glass. This is also one of the reasons why OnePlus used sapphire crystal displays on the OnePlus Watch.

However, sapphire crystal production is not only rather limited in the current industry, but also very costly, especially for large displays that span a considerable surface area. Therefore, sapphire crystal displays are still more suited to smaller devices such as watches and camera lenses currently.

Furthermore, the light transmission coefficient of sapphire can only reach about 88%, while glass can reach about 92%. From this perspective, glass is more valuable and efficient as a smartphone display material. Moreover, even though sapphire crystal is extremely tough and scratch resistant, it is also quite brittle and susceptible to screen shattering. This is why the industry is currently more willing to go with glass on smartphone displays.

2. What sort of engineering and design challenges do materials like stainless steel, sapphire, ceramic, and titanium impose on smartphones?

For ceramic, the current colors that boast a more refined texture are limited to black and white, the visual effects and color selection of which are not as rich as those that can be achieved with glasswork. However, ceramic has a higher hardness rating and better abrasion resistance compared to glass. The material itself also allows a smoother and more refined texture, brighter reflections and a more radiant appeal. This is why OnePlus adopted a ceramic back cover for the OnePlus X. We will continue to research and explore new ways to potentially incorporate ceramic into our smartphones.

In regard to titanium materials, the processing times are two to three times longer than aluminum alloys and is more difficult to process due to its extremely high hardness rating.

3. Can you expand on this with some real-world examples for how Cobalt affected the design of the OnePlus Watch?

Cobalt has excellent resistance properties and toughness, making it a great material for the OnePlus Watch; however, it’s more challenging to process overall. The service tools used to process cobalt alloys have a reduced lifespan compared to ones used for processing stainless steel. Currently, most manufacturing plants have little experience in mass production of cobalt alloys. It's also more challenging and time-consuming to apply processes such as material polishing to cobalt alloys than stainless steel. In short, there is a lot to consider if we wanted to incorporate the material into smartphones.

4. Same question as above, but for cost — how much more expensive would some or all of these materials make phones?

The overall cost is mostly decided by the actual structural and industrial design plans, and material is just one of the factors. Using the abovementioned materials would be more expensive due to the increase in processing difficulty and processing time. It’s hard to say what the actual difference in numbers would be.

5. Are phones made of stainless steel, sapphire, ceramic, or titanium any more durable than the usual aluminum and glass designs?

The current materials already meet the industry requirements and the majority of use cases.

If the above materials are used, the lifespan of certain components may be improved, but the device as a whole will unlikely see a significant improvement. Improvements will likely be more apparent when it comes to the texture and outer appearance. For example, although stainless steel has a fantastic hardness rating, a midframe engineered with aluminum alloy is also hard enough. If we used sapphire, the display will certainly be more scratch and wear resistant, but also more brittle and susceptible to shattering. For OnePlus, we take several factors into considerations such as user demands and user experience before selecting the right materials to build our smartphones.

6. Is there any chance OnePlus might release a stainless-steel phone someday?

Anything is possible, but at the moment we do not have any specific plans for a stainless-steel phone. We will continue to explore ways to incorporate new materials into our devices, so long as it helps us design the best Android flagship to deliver a more refined user experience.

7. What sort of engineering challenges and costs are associated with natural materials like wood (including bamboo), leather or other materials? And can phones that use these materials still be durable enough for customers?

Over the past eight years, we've worked with a variety of materials like wood, bamboo and leather – both on smartphones and accessories. There aren't many technical challenges in working with these kinds of materials, but from our experience we've generally found that materials like glass and metal offer more interesting textures, richer visual effects and better durability, especially for premium and ultra-premium devices. For example, synthetic leather might be a more durable option than natural leather, but there are many other factors that we have to keep in mind that influence the user experience as well.