On August 30, Nippon Steel Chemical Materials Co., Ltd. developed the "Espanex" 2 series of circuit board materials for high-frequency markets such as the fifth generation communication (5G).
The "F series" is mainly used in smart phones, and its dielectric loss is reduced to half of the original product. The "Z series" is applied to 5g base stations. At present, this series of products has been put on the market for sale.
It is understood that Espanex is an adhesive-free copper-clad laminate (FCCL) for flexible printed circuit boards, which is mainly produced by casting polyimide resin directly on copper foil through original polyimide design and synthesis techniques.
At present, the company's circuit board materials account for 25% of the global double-layer FCCL market.
Nippon Steel is also developing and producing the corresponding low-dielectric polyimide. The dielectric layer of the F series is controlled below 50 μm. The production of the low-dielectric polyimide of the M series is still progressing, and the production capacity is expected to reach 12 million. Square meters / year.
Because 5G network frequencies are much faster than 4G, many base stations need to be installed to meet expected demand. In response to this situation, the company has also developed the "Z series" with a dielectric layer of 50 microns or larger, which will be used in 5G base stations in the future.
It is reported that the annual production capacity of Z series is about 1.2 million square meters. At present, both the "Z series" and "F series" products have been sampled and have the opportunity to reach cooperative shipments.
With the development of 5G technology and the introduction of flexible mobile phones by multiple brands, FCCL and related films have become the focus of attention. Relevant information shows that most of the insulating base films of FCCL are polyimide (PI) films.
In 5G applications, the application of liquid crystal polymers (LCP) with low dielectric properties is also continuously developing. Nippon Steel Chemical believes that LCP is difficult to process due to its poor adhesion, but the polyimide developed by the company has reduced the dielectric loss while using the adhesion. Compared with LCP, low-dielectric polyimide (PI) film is superior.
However, there are still many people in the market who believe that polyimide (PI) films have various shortcomings. For example, the PI film is too hygroscopic, which may cause the reliability of FPC to decrease under high temperature conditions.
In addition, the curling phenomenon caused by the PI film after moisture absorption will cause problems in use. Therefore, the industry is continuously working on the development of new high-performance polymer materials in order to replace the PI film. The most influential is the liquid crystal polymer (Liquid Crystal Polymer, LCP for short).
From the basic properties of the film, this kind of polymer materials can completely make up for the defects of PI film, including low hygroscopicity, low thermal expansion coefficient, low dielectric constant and high dimensional stability.
The following figure lists the basic performance comparison of typical LCP-based FCCL and PI-based FCCL. The disadvantage of LCP-based FCCL is its low peel strength.
Although LCP has excellent performance, it also has disadvantages such as difficult to control the molding process, anisotropic physical properties of the product, poor mechanical properties in the direction perpendicular to the shear flow during molding, and easy fibrillation. Modified to improve the mechanical properties of LCP film. On the other hand, LCP raw materials are expensive, which leads to higher LCP prices. This is the most important problem affecting the development of LCP. Therefore, reducing costs has become the research focus of manufacturers.
In addition, due to the high price of LCP substrates, and the current PI soft board can no longer meet the needs of consumers, modify PI has appeared. Although modify PI is not as good as LCP in terms of transmission loss, dimensional stability, and bendability, it can also improve its efficiency by improving the fluoride formula, and its cost is only 70% of LCP.
Previous news also revealed that the LCP soft board originally planned for the new Apple iPhone will also be replaced by modify PI.
On May 29, 2018, according to Yan Zhiming, general manager of Taiwan Taihong Technology, Taihong currently does not participate in the production of the LCP material market, but produces heterogeneous PI (Modify PI) products. Starting in 2019, Massive attack on the non-Apple mobile phone camp market.
In addition to Taihong Technology, Taiwan's Xinyang Technology also completed the development of Modify PI products last year. Xin Yangke said that the Modify PI products will continue to use the advantages of the original manufacturing process and have relatively low price incentives. Under the requirements of 5G communication transmission, it is expected that there will still be at least 2 years of market competitive advantage.