Encapsulation is the key process in manufacturing optoelectronic devices, which directly affects the performance, reliability, and cost of the devices. Currently, there are no national or industry standards for testing the performance of ceramic substrates. Its main performance includes substrate appearance, mechanical properties, thermal properties, electrical properties, packaging performance and reliability.
The electrical performance of the ceramic substrate mainly refers to whether the metal layers before and after the substrate conduct electricity (whether the quality of the internal through holes is good). Due to the small diameter of the through holes in DPC ceramic substrates, defects such as unfilled holes and holes may occur during the plating and filling process. Generally, an X-ray inspection system can be used for quality inspection.
For example, in the packaging of IGBT, due to the high output power and large heat generation of IGBT, the chip may be damaged due to poor heat dissipation. Heat dissipation is a key technology in IGBT packaging, and ceramic substrates must be used to enhance heat dissipation. The main reason for using DBC ceramic substrates in IGBT packaging is that the metal circuit layers of the DBC substrate are thicker, have high thermal conductivity, high heat resistance, high insulation, high strength, low thermal expansion, and resistance to corrosion and radiation. It is widely used in the packaging of power equipment and high-temperature electronic equipment.
X-ray inspection machine is used to identify and recognize solder joint defects that may occur during the packaging process, thereby eliminating products with defects such as wrong soldering and leakage soldering. With the continuous development of semiconductor technology, power devices will gradually develop towards high power, miniaturization, integration, and multi-functionality. Higher requirements have been put forward for the performance of ceramic substrates for packaging, and their inspection is more difficult.
High precision and miniaturization of ceramic substrates. In order to meet the development requirements of device miniaturization, it is necessary to continuously improve the processing accuracy (line width / line spacing) of the ceramic substrate circuit layer. With the fine development of electronic equipment, the accuracy of the X-ray inspection machine has been improved, and it has timely adapted to the needs of the production line.
Integration of ceramic substrates. Generally, ceramic substrates are only suitable for making single-sided circuit layers. If the upper and lower layers are to be connected, laser drilling is required, and then metal paste is filled in the holes, and then sintered. The conductivity and thermal conductivity of the metal layer in the hole are poor, and the reliability of the substrate is low. Integration means the complexity of the product inspection table, so X-ray 3D tomography imaging can be used for packaging inspection of such electronic devices, which can effectively avoid image overlap and occlusion of highly integrated electronic devices.
DPC ceramic substrates use laser drilling and electroplating hole filling technology to prepare through-hole metals. Since the holes are electroplated and filled with dense copper columns, the conductivity and thermal conductivity are excellent, so the vertical interconnection of the upper and lower circuit layers on the ceramic substrate can be achieved. With the development of third-generation semiconductor technology, power devices have begun to rapidly develop in semiconductor lighting, power electronics, microwave RF, 5G communication, new energy, and new energy vehicles, and the demand for using ceramic substrates has surged. Ceramic substrates play a crucial role in power device packaging and are key electronic materials developed by various countries. Therefore, there is an urgent need to strengthen the research and development of core technologies for ceramic bodies (including ceramic powders, substrates, and substrate preparation technology, etc.) to meet the rapidly developing market demand in China. X-ray inspection machine technology will also closely monitor the development of packaging technology and effectively serve product quality inspection.