Advanced Institute of Technology: How to solve the problem of millimeter wave signal attenuation with LCP gold-plated film?

From 5G smartphones to low Earth orbit satellites, this "golden film" is connecting the era of the Internet of Things.

With the accelerated evolution of 5G towards 5.5G and even 6G, communication frequency bands are constantly extending towards the millimeter wave region. The higher the frequency, the more significant the attenuation of the signal in the transmission medium - this has become one of the core bottlenecks restricting the development of high-frequency communication. Liquid crystal polymer (LCP) films are becoming a key material for solving this problem due to their excellent dielectric properties. ButLCP thin film gold plating technology of Advanced Institute (Shenzhen) Technology Co., LtdFurther transform the material advantages of LCP into high-performance solutions that can be mass-produced.

1、 LCP film: a substrate naturally designed for high frequencies

The reason why LCP film stands out in the competition for high-frequency communication materials is due to a complete set of performance combinations.

Ultra low dielectric loss.The dielectric constant of LCP can be as low as 2.9, and the loss factor can be as low as 0.001-0.003 (@ 10GHz), maintaining stable dielectric performance in the ultra wideband range of 1GHz to 75GHz. In contrast, traditional polyimide (PI) films experience a sharp increase in dielectric loss at high frequencies, making it difficult to meet the requirements of millimeter wave applications.

Extremely low moisture absorption.The water absorption rate of LCP film is less than 0.1%, while the water absorption rate of traditional PI material is as high as 1.5%~2.2%. In practical environments with varying humidity, the extremely low moisture absorption effectively avoids the scattering and absorption of high-frequency signals by moisture.

Excellent dimensional stability.LCP has high strength, high heat resistance, extremely low coefficient of linear expansion, and excellent flame retardancy, making it suitable for high-end fields such as aerospace, military, and 5G communication.

2、 Millimeter wave signal attenuation: how to break through LCP gold plating?

LCP film itself is an excellent insulating material, and in order for it to function in high-frequency circuits, it must be metalized. However, the surface energy of LCP is relatively low (about 32mN/m), with strong chemical inertness, making it difficult for the metal layer to firmly adhere directly.

Advanced Institute Technology has broken through this bottleneck through two core technologies:

Plasma pretreatment technology.By plasma treatment, the roughness and active sites of LCP surface are increased, creating favorable conditions for subsequent metal deposition. Research has confirmed that oxygen-containing plasma pretreatment can introduce more polar functional groups on the surface of LCP substrate, significantly enhancing the bonding strength between PVD metallization layer and LCP.

Gradient transition layer process.Using titanium (Ti) or chromium (Cr) as transition layers to achieve stress transition from the substrate to the functional metal layer.

By combining this technology, the adhesion of the gold layer on the surface of LCP is achieved5B level standard——The highest level of adhesion testing in the industry. The uniformity of the company's product coating can reach ± 5%, and it can maintain stable performance even under repeated bending or high and low temperature environments.

3、 Low temperature gold plating: guarding the "soul" of LCP

LCP material is temperature sensitive - excessive temperature can damage its molecular structure, leading to degradation of dielectric properties. The Advanced Institute of Technology has successfully developedLow temperature gold plating processReduce the film processing temperature toBelow 150 ℃While ensuring the quality of gold plating, it effectively avoids the degradation of material properties. The company also develops a low-temperature plating solution formula to control the material's thermal shrinkage rate within 0.05%, perfectly adapting to the dimensional accuracy requirements of precision electronic components.

In terms of thickness control, the total thickness of gold-plated LCP film can be12 μ m to 100 μ mCustomization within the scope. Taking 5G antenna substrate as an example, the thickness of the gold layer needs to be precisely controlled within0.1~0.5μm——Too thin leads to insufficient conductivity, while too thick sacrifices flexibility. The resistivity of gold is about 2.44 μ Ω· cm, and a high-purity gold layer is the fundamental guarantee for low loss signal transmission.

4、 Full range of metalized product matrix

Advanced Institute Technology has established a complete LCP coating system covering multiple metals:

Gold plating (Au)The main functional coating has good conductivity, strong oxidation resistance, and biocompatibility. Suitable for high-frequency scenarios such as 5G/6G millimeter wave antennas and high-speed connectors for AI servers.

Copper plating (Cu)The core conductor material of high-frequency copper-clad laminate (LCP-FCCL). LCP-FCCL is made using LCP film as the dielectric substrate through high-temperature vacuum lamination process. The thermal expansion coefficient of LCP is similar to that of copper, and it is not easily deformed at high temperatures. It can withstand high temperature processes such as SMT surface mounting.

Silver plating (Ag)Extremely high conductivity (resistivity of about 1.59 μ Ω· cm), suitable for high-frequency scenarios such as millimeter wave antennas and flexible circuit boards.

Nickel plating (Ni)Mainly used as a barrier layer to prevent the diffusion of copper.

Titanium (Ti) plating and chrome (Cr) platingAs a transition layer, it is the key to enhancing the adhesion of precious metals on LCP.

Frontier exploration - niobium titanium (NbTi) platingThe company has conducted experimental research on LCP thin film coated with niobium titanium. According to test data, the signal attenuation rate of LCP thin film coated with niobium titanium is reduced by about 30% compared to traditional materials in the GHz frequency band.

5、 From laboratory to mass production: roll to roll scale production

The real barrier to the coating industry lies in the ability to go from laboratory samples to kilometer level mass production. Advanced Institute of Technology has independently builtRoll to roll continuous vacuum coating production lineThe physical vapor deposition (PVD) process combining magnetron sputtering and vacuum evaporation can continuously deposit metal layers on the surface of flexible polymer films, achieving large-scale production. The company's applicable substrates include various flexible materials such as FEP, PI, PET, LCP, PPS, PEN, PP, etc. It supports flexible customization of parameters such as film width of 10-620mm, coating thickness, and tolerance range. From material pretreatment, surface treatment, coating deposition to finished product testing, the company has achieved precise control and process optimization throughout the entire process.

6、 Application Implementation: From ZTE to Low Earth Orbit Satellites

Advanced Institute Technology's LCP gold-plated film products have achieved mature applications in multiple high-end fields.

High frequency communication fieldIt is the largest application market. At the base station end, Advanced Institute Technology andZTE CorporationThe gold-plated LCP film developed in collaboration has been28GHz millimeter wave base stationRealize large-scale application in China, reducing single base station signal attenuation to0.3dB/mWhen used as a 5G mobile phone millimeter wave antenna substrate in mobile terminals, this product is thinner and lighter (with a thickness of less than 0.05mm) compared to traditional PTFE materials, and has better mechanical strength. This product can supportAbove 40GbpsThe ultra high speed transmission has become the preferred material for AI server GPU interconnection and USB4/Thunderbolt data cables.

Automotive ElectronicsIn the field of intelligent driving, LCP gold-plated film can be used in 77GHz vehicle mounted millimeter wave radar systems-50 ℃ to 200 ℃Maintain signal stability within a wide temperature range. The chemical stability of the gold plating layer effectively resists the corrosion of various chemical media such as brake oil and coolant.

Aerospace fieldThe domestic LCP fiber has entered the low orbit satellite supply chain and is applied to the core layer of satellite flexible solar wings. LCP gold-plated film can be used as signal transmission components for satellite communication antennas due to the lightweight and high strength of the LCP substrate and the radiation resistance of the gold-plated layer.

Medical ElectronicsIn the field, with good biocompatibility and precise size control, LCP film gold plating is also applied in the manufacturing of medical devices such as implantable devices and minimally invasive surgical instruments.

7、 Conclusion: Connecting a smarter future with precision coating

From 28GHz millimeter wave base stations to 77GHz vehicle mounted radars, from high-speed connectors for AI servers to flexible solar wings for low orbit satellites, LCP gold-plated films are becoming the "invisible infrastructure" supporting the era of the Internet of Things.

Advanced Institute (Shenzhen) Technology Co., Ltd. was established in 2016, headquartered in Bao'an District, Shenzhen. It is a national high-tech enterprise specializing in shielding materials, insulation materials, thermal conductivity materials, and precious metal coatings. The company has passed ISO9001 quality management system certification, and its products comply with GJB 773A military standards and RoHS environmental requirements. It has the ability to support high-end fields such as aerospace, military, and 5G communication.

In the field of LCP thin film metallization, the company5B level adhesionThe gold plating processBelow 150 ℃Low temperature gold plating technologyRoll to roll continuous vacuum coatingThe large-scale production capacity and the full range of metallization solutions covering gold, silver, copper, nickel, titanium, chromium, etc. provide reliable material solutions for the signal transmission problems in the era of high-frequency communication. In the future, Advanced Institute Technology will continue to deeply cultivate the field of precision coating, and pave every inch of the "signal road" for the 5G/6G era with continuous technological innovation.