Materials for ADAS components
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Vehicle-mounted cameras require materials that offer a good balance of outstanding properties in several key areas.

• Dimensional stability ⇒ Precision optical properties
• High strength ⇒Reliability over long product lifetimes
• Good bonding properties ⇒ Reliability of bonding regions
• Weather resistance ⇒ Reliable performance and attractive appearance retained when used in outdoor environments

For a wide variety of vehicle-mounted camera components—including lens barrel, lens spacers, and chassis bodies—Asahi Kasei recommends our XYRON™ XP640, AA105 (development product), and DG040.

The figure below shows the results of aging tests in which several resin materials were formed into the shape of a lens barrel, then subjected to aging with periodic measurements to assess their ability to retain a precisely circular shape (a property known as circularity). XYRON™ DG040 exhibited high circularity from the earliest stages of the experiment—and minimal variation with aging, demonstrating that this material offers particularly outstanding dimensional stability. XYRON™ XP640 and AA105 (development product) also exhibited minimal dimensional variation with aging, confirming the excellent dimensional stability of these materials as well.

■ XYRON™ XP640 / AA105 (under development)
These are alloy grades blending PPE with high heat-resistant Polyphthalamide (PPA). When PPE, a material famous for its low water absorption, is alloyed with PPA, the result is a material offering the high heat resistance and high strength of PPA, but exhibiting minimal dimensional variation due to low water absorption. AA105, a product currently in development, boasts greater weather resistance than XP640 and features high laser transmissivity, making it suitable for laser welding.

Click here to view the XYRON™ XP640 datasheet.

■ XYRON™ DG040
This is an alloy grade blending PPE with PPS. Its key advantages include (a) minimal degradation in mechanical strength in high-temperature environments, and (b) minimally anisotropic dimensional variation thanks to specialized glass-fiber reinforcements.

Click here to view the XYRON™ DG040 datasheet.

The materials used to make camera components must offer high dimensional accuracy with minimal variation in component dimensions and dimensional stability across a range of operating environments. For enclosures, it is particularly important to choose materials that are attractive in appearance.

Meanwhile, room mirror brackets are no longer simply mounting points for mirrors, as was true in the past; instead, these components have begun to acquire various new types of sensing capability. This, in turn, imposes new requirements on the materials from which these components are made: materials must be heat-resistant, to ensure they can withstand the heat generated by sensing components, and must offer high rigidity to support increased weight.   The resin materials used here must be attractive in appearance—as they will be used for interior components—and must offer high rigidity for vibration suppression and minimal variation in component dimensions or material properties upon water absorption.

■LEONA™ SG105/SG115 resin materials reduce variations in component dimensions and material properties due to water absorption and offer excellent strength and rigidity together with an attractive appearance.
Asahi Kasei’s LEONA™ SG105 and SG115 polyamide resins are alloy grades that blend semi-aromatic polyamide 6I with polyamide 66.
These materials feature reduced variation in component dimensions and material properties due to water absorption, and offer high relative strength, high rigidity, attractive appearance, and excellent fluidity.

Click here to view the LEONA™ SG105 datasheet.

Vehicle-mounted radars comprise two main components: an antenna mount and an enclosure. The enclosure serves not only to protect the antenna mount, but also to send and receive electromagnetic signals; for this reason, it is often known as a radome.

Because the radome is the outermost component of the radar system, it must be lightweight and weather-resistant; in addition, the radome should have low dielectric permittivity to achieve optimal electromagnetic-wave transmission. The need to minimize electromagnetic attenuation in the radome is particularly urgent for high-frequency systems such as millimeter-wave radars. Consequently, the relative dielectric permittivity (Dk) and loss tangent (Df)—physical properties describing the attenuation of electromagnetic waves in a material—are important characteristics of the materials used to fabricate radar components. Materials with high Dk or Df tend to exhibit significant absorption of electromagnetic waves, increasing signal losses and reducing sensitivity.

The parent material of Asahi Kasei’s XYRON™ products is polyphenylene ether (PPE), whose low dielectric permittivity and low loss tangent make it well-suited for use in information and communication systems. PPE also features a high glass transition temperature, and its dielectric properties are less temperature-dependent than those of other high heat-resistant resins. These are important advantages for ensuring stable, high-quality communication across a wide range of operating temperatures.

In particular, AA181-7 is a XYRON™ development grade with excellent hydrolysis resistance and shock resistance that simultaneously offers low dielectric permittivity and compliance with the UL94V-0 flame-retardant standard, a combination that is nearly impossible to achieve using conventional materials.

To date, radomes have typically been made from polycarbonates (PCs), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), or similar materials, but these choices leave much to be desired from the standpoint of dielectric properties. In particular, the material properties of crystalline resins such as PBT and PPS vary significantly at temperatures beyond their glass transition temperature (Tg); in particular, the dielectric permittivity of such materials in high-temperature environments must be carefully monitored.

These problems may be eliminated once and for all by choosing Asahi Kasei’s XYRON™ AA181-7 development grade as a material for radomes. Asahi Kasei is also developing additional XYRON™ grades for use as radome materials, including grades that resist color changes induced by light exposure. The XYRON™ family of materials is the right choice to satisfy a wide range of specifications for millimeter-wave radar enclosures.

Resin materials for use in head-up displays must offer high dimensional accuracy—with minimal dimensional variation at high temperatures when mounted in vehicle dashboards—to ensure that mirrors properly reflect and project display images.

For head-up displays, Asahi Kasei recommends the following two XYRON™ grades.

XYRON™ DG040
XYRON™ DG040 is an alloy grade blending PPS with PPE. Adding PPE to PPS improves dimensional stability at high temperatures, while the addition of specialized glass fillers reduces anisotropy in dimensional variations.

Click here to view the XYRON™ DG040 datasheet.

XYRON™ 744Z
XYRON™ 744Z is an alloy grade blending PPE and PS. This material offers compliance with the UL V-0 flame-retardant standard, a heat deflection temperature of 135°C, and a good balance of heat resistance, toughness, and dimensional stability.

Click here to view the XYRON™ 774Z datasheet.