5G Brings the Upgrade of Antenna and Greater Market for LCP

After the launch of 5G mobile phones by major brands, Apple seems to be inactive. The iPhone 11 series launched at the fall of 2019 is still a 4G series. In fact, Apple is likely to be waiting for the peak of the cellphone replacement. In the antenna design, liquid crystal polymer (LCP) and modified polyimide (MPI) were applied, and this has laid the foundation for the research and development of 5G mobile phones.

LCP market will expand with 5G development

The construction of 5G is still the early stage, and the communication frequency is not much different from the 4G period, and the communication wavelength is still in centimeter band. As 5G develops from low frequency to high frequency, the communication frequency will be 6 to 10 times that of nowadays, and the communication wavelength will enter the millimeter stage. After entering the high-frequency and high-speed 5G era, the traditional antenna material PI, which has already revealed its inferiority, is bound to be eliminated.

Requirement of each 5G stage differs

In the 5G stage of high frequency and high speed, PI material cannot be applied. In contrast, LCP materials are effective in reducing signal loss and maintaining dielectric stability. The demand for the appearance of a mobile phone such as a folding screen and a slim body makes the space inside the mobile phone smaller and smaller, which also places more demands on the antenna material. The LCP material has good bendability and can optimize the utilization of the internal space of the mobile phone by bending or folding, which is preferable for the antenna material for high-frequency and high-speed 5G era.  

MPI material performances moderate

Although LCP has low transmission loss, good bendability and high stability, it lacks heat resistance. The MPI material modified by PI can maintain qualified signal processing ability below 15Ghz, and it is more advantageous in price than LCP material. Moreover, MPI has good performance in all four aspects of heat resistance, transmission loss performance, bendability and stability. Therefore, it is the preferred antenna material during the transition period of 5G from low frequency to high frequency.

What should be noticed is that LCP is technically the best choice for antenna material in the 5G era of high-speed and high-frequency, but in practical applications, the performance of LCP antennas has not yet reached theoretical height. Many consumers report that the iPhone X series (with six LCP antennas built in) often suffer from signal disconnection, and this signal connection has been improved in the iPhone 11 series (with two LCP antennas and four MPI antennas).

However, it is difficult to confirm whether Apple replaced the LCP antenna with an MPI antenna for cost reduction or the lack of qualified LCP antenna solution. In addition to the antenna material, the transmission and reception of signals is also heavily influenced by the antenna layout. With qualified and optimized layout design, the LCP material will present obvious advantages as the antenna material. Moreover, the number of antennas for 5G mobile phones is 2-3 times that of 4G mobile phones, and this would make some difference.

AiP is currently the best LCP solution

LCP materials usually need to be processed before they assume the role of antenna material. The common LCP flexible printed circuit board (LCP FPCB) is made of flexible copper clad laminate (FCCL), LCP material and a small amount of other materials. The LCP FPCB, also called the LCP antenna, performs good in millimeter waves and is an ideal antenna for the high-frequency and high-speed 5G era.

The antenna in package (AiP) is based on the LCP FPCB, and then with RF front end, transceiver and other components integrated together on it. And this can reduce metal interference inside the mobile phone and maximize the space. Leading other companies, Qualcomm has introduced a 5G antenna module based on AiP technology. The module integrates 5G wireless transceivers, power management ICs, RF front-ends and antenna arrays, and is a benchmark product which other manufacturers should learn from.

High production concentration, low cost ratio

At present, the annual global production capacity of LCP materials is over 77,000 tons, all of which are concentrated in Japan, the United States and China. The United States entered the LCP industry at the earliest, followed by Japan. Although China lags behind the United States and Japan, it is growing at a faster rate.

Among the top producers of LCP materials, Celanese, Polyplastics, Sumitomo Chemical, JUJIA and JXTG are among the top five producers. The number one Celanese is from the United States, JUJIA is from China, and the other three are Japanese companies.

In terms of cost, the unit price of LCP materials is higher than that of MPI materials, but it has not a high ratio in antenna cost. The cost of the LCP antenna is mainly concentrated in the FPCB manufacturing process, and the LCP material only accounts for about 15%. Among the costs of LCP antenna modules based on AiP technology, the proportion of LCP materials is lower.

LCP material accounts for only 15% in costs