Ushio Inc. is pleased to announce the launch of the industry-leading "epitex F-Series" flip-chip LEDs. These LEDs offer a SWIR range of 1050nm to 1900nm and feature a compact design. Sample shipments began in August 2024 (see Figure 1 and Table 1 for specifications).
We are pleased to share this newly developed chip, an innovative achievement and the world's first flip-chip structure using InP (Indium Phosphide) material. This innovative design eliminates the need for overhead current-supplying wires, significantly reducing the required chip height and enabling thin LED packaging. Furthermore, the absence of overhead wires eliminates the need for side conductive spaces in the package, allowing for high-density applications. This is particularly beneficial when multiple LED chips are arranged together, facilitating miniaturization of the package. The wire-free design also eliminates the shading effect caused by wires on the light-emitting surface, simplifying optical design (see Figure 2).
In terms of performance, the absence of electrodes on the light-emitting surface maximizes light extraction efficiency. Despite its small size of 270μm × 170μm, the chip achieves the same light output as a high-brightness SWIR LED chip with a size of 320μm × 320μm from the "epitex D series". Given these superior characteristics, it is expected to make a significant contribution to space-constrained devices, such as smartphones and other small electronic devices, vital sign sensors, and proximity sensors.
*1 According to Ushio's research
Figure 1 Table 1
Figure 2
Main applications
- Biosensor Light Source
- Mobile device biosensing light source
Contributions to the Field of Biosensing <br /> We believe that SWIR flip chips can also make valuable contributions to the field of biosensing. The SWIR field includes a "second biowindow*2" at 1100-1350nm and a "third biowindow*2" at 1550-1800nm, which has a deeper penetration depth into biological tissues. This allows light to reach deep into tissues non-invasively, providing more accurate information on the fine structures and lesions within biological tissues (see Figure 3).
Furthermore, the SWIR field encompasses the absorption bands of many substances, such as water, glucose, ethanol, and cholesterol. These substances can be detected and accurately quantified by analyzing the transmittance and absorptivity of SWIR light, making it easier to monitor important biomarkers. We estimate that this advancement will significantly advance research in the field of biosensing and improve the accuracy of non-invasive biological diagnostics. Moreover, since flip-chips do not require wires to conduct current, they can be mounted on flexible substrates. The lightweight and flexible nature of flexible substrates makes them ideal for use in electronic devices, further reducing their weight and size (see Figure 4). This is expected to promote the miniaturization of mobile devices and medical sensing devices that continuously monitor vital signs in the future.
*2 Infrared light with wavelengths of approximately 700-2500 nm is less scattered and absorbed by molecular vibrations in biological tissues, making it suitable for observation and sensing of deep tissues. This wavelength range is known as the "biological window".
Figure 3 Figure 4
The USHIO flip chip has a certain height difference between the anode and cathode electrodes, and the electrode size is relatively small. Therefore, it is recommended to use solder with a particle size of approximately 20μm or less for mounting.
For detailed specifications, please refer to the official website of USHIO INC.
