PCB Technical - Alumina ceramic circuit board application

Alumina ceramic PCB may be a completely unfamiliar concept to many people, but what people don’t know is that it is actually widely used in our daily life and is committed to improving people’s lives. Today we will discuss it. One of the many applications of alumina ceramic circuit boards-CMOS image sensor (Complementary Metal-Oxide Semiconductor Image Sensor)

The camera of a smartphone is like its eyes. In our daily life, we cannot do without him taking pictures, recording videos, scanning QR codes, facial recognition and so on. The image sensor is like the retina of the smart phone's camera by using the photoelectric conversion function of the photoelectric device. Convert the light image on the photosensitive surface into an electrical signal proportional to the light image. Compared with the photosensitive element of the "point" light source such as photodiode and phototransistor, the image sensor is a functional device that divides the light image on its light-receiving surface into many small units and converts it into usable electrical signals.

Image sensors are mainly divided into two types: CCD (Charge Coupled) and CMOS (Complementary Metal Oxide Semiconductor). CCD can provide better image quality, noise immunity and flexibility in camera design. Although the size and complexity of the system are increased due to the addition of external circuits, it can be more flexible in circuit design. CCD is more suitable for applications that require very high camera performance and less stringent cost control, such as astronomy, high-definition medical X-ray images, and other scientific applications that require long exposures and strict requirements for image noise.

CMOS is an image sensor that can be produced by applying contemporary large-scale semiconductor integrated circuit production technology. It has the characteristics of high yield, high integration, low power consumption, and low price. CMOS technology is a technology that many image sensor semiconductor R&D companies in the world are trying to use to replace CCD. After years of hard work, as an image sensor, CMOS has overcome many early shortcomings and has developed to a level that can compete with CCD technology in terms of image quality. Compared with CCD, CMOS has the advantages of small size, power consumption less than 1/10 of CCD, and 1/3 cheaper than CCD. Make them more suitable for applications that require small space, small size, low power consumption, but not particularly high requirements for image noise and quality. For example, most of the industrial inspection applications with auxiliary lighting, security applications, most mobile phone camera applications, and most consumer commercial digital camera applications.

CCD and CMOS have their own advantages in different application scenarios. However, with the continuous improvement of CMOS technology and technology, the disadvantages of high cost and high power consumption of CCD are difficult to improve, and the price of high-end CMOS continues to fall. I believe that in the future development, CMOS will occupy an increasingly important position.

Taking pictures has become the key to the differentiation of smart phones, driving the growth of CMOS image sensors

In the increasingly saturated market of smartphones, PCB manufacturers have already regarded camera innovation as a key component to differentiate from their competitors. Three cameras and four cameras have long been commonplace. The quality of a mobile phone’s photography is extremely great. Most consumers will give priority to the issue when buying. New types, diversification, and more advanced biometrics of camera functions require more advanced imaging technology. Consumer demand has further promoted the growth of the image sensor market.

CMOS image sensors quickly occupy the image sensor market due to their cost-effectiveness, fast processing speed and low power consumption. But is there really no way for CMOS to go further? Heat dissipation and sensitivity are still the "pain points" of CMOS. At this time, the alumina ceramic circuit board is needed.

Heat dissipation management, improve the life of CMOS image sensor

The CMOS image sensor light signal acquisition method is active, and the charge generated by the photodiode is directly amplified and output by the transistor. When processing fast-changing images, the current will frequently change and the flow will increase, causing it to overheat. Affect the life and reliability of CMOS image sensors. Due to the small size of the CMOS image sensor, most of the heat cannot be dissipated from the surface. If you want to achieve better heat dissipation, you can only start from the circuit board. Traditional materials FR-4 and FE-3 cannot meet the requirements of CMOS image sensors. With its high thermal conductivity (20~27W/mK), Stoneon alumina ceramic circuit boards can meet the high heat dissipation requirements of CMOS image sensors, and the ceramic material itself has high strength, hardness, thermal shock resistance, insulation, and chemical properties. Stability, good adhesion to metal, can further extend the life cycle of the product.

Sensitivity is increased and the pixels of CMOS image sensor are improved.

Each pixel of the CMOS image sensor contains an amplifier and A/D conversion circuit. Too many additional devices compress the surface area of the photosensitive area of a single pixel, so that the sensitivity of the CMOS image sensor is low. CMOS image sensor suppliers have been reducing Work hard with small pixel pitch. Stone alumina ceramic circuit boards can be assembled in high density (line/spacing (L/S) resolution can reach 20μm), which is a good helper to realize the integration and miniaturization of equipment.

Ceramic metallization technology includes HTCC, LTCC, DBC, DPC and other process methods, but only DPC thin film technology uses magnetron sputtering to firmly combine copper and ceramic substrates, so the metal crystallization performance of ceramic circuit boards is good, The flatness is good, the circuit is not easy to fall off, and has reliable and stable performance, thereby effectively improving the bonding strength of the chip and the substrate, which is conducive to the quality control of the CMOS image sensor. In addition to the above advantages, ceramic circuit boards using DPC thin film technology can also achieve three-dimensional substrates and three-dimensional wiring. They have good corrosion resistance and keep the circuit in a constant temperature state, which is more conducive to the consolidation and strengthening of the performance and characteristics of CMOS image sensors.

The ceramic circuit board can not only meet the performance requirements of CMOS image sensor for heat dissipation, life cycle, and realize equipment integration and miniaturization, but also can give full play to the advantages of CMOS image sensor and ensure that its disadvantages can be minimized.

At present, CMOS image sensors are developing in the direction of high resolution, high sensitivity, integration and intelligence. And gradually replace the CCD, there is no doubt that the CMOS image sensor market will not stop here, will have a better development prospects. As a professional ceramic PCB manufacturer, we will follow the market direction and devote ourselves to producing better ceramic substrates to better serve our lives.