In the process of IC packaging, some substances such as pollutants and dust will appear on the chip to destroy the use of the process, so we need to do a certain amount of cleaning work on the IC packaging process. Certain cleaning work should be carried out both before and during the loading process. In the packaging process, plasma cleaning of the lead frame before the lead bonding process can effectively remove these impurities and improve the yield and quality of the product. This paper mainly introduces the application of on-line plasma cleaning technology in IC packaging.

Basic principle of IC packaging process

The use of circuit protection it plays a lot of protection on the package circuit, and can be used for electric heating protection of the whole chip through installation, fixing, sealing, etc., to prevent electric heating plays a huge role; In addition, it also connects with many contacts on the chip to get some enclosures on the package, and these enclosures are then used to connect the internal wires of the printed circuit with the wires of other electronic parts, so we can directly use the internal and external circuits to connect. At the same time, the chip must be isolated from the outside world to prevent pollutants in the air from entering the internal chip, and the pollutants on the surface of these chips will greatly reduce the quality of the product. In the packaging process, technical principles such as loading and leads require our cleaning to completely remove these contaminants effectively.

IC packaging process flow

The packaging of the IC is carried out during the packaging process and then put into practical application. Several major steps of integrated circuit packaging are gradually analyzed in the pre-process, intermediate process and post-process (the former process is shown in Figure 1 below). With the continuous development of the packaging process, some changes have taken place, and the general steps of the process are:

Patch: The silicon wafer is fixed and cut with a protective film and a metal frame; Slicing: The silicon wafer is cut into a single chip and checked repeatedly;

Chip mounting: put the silver glue or insulating glue in the corresponding position, remove the cut chip from the scribing film, and paste it on the fixed position on the lead;

Bonding: Connect the pin of the lead hole and frame on the chip with a gold wire to make the internal and external circuits connected. To make internal and external circuits connected; Encapsulation: Encapsulating the circuit of the original, enhancing the physical characteristics of the original to protect it from loss and damage;

Post-curing: curing plastic packaging material, so that it has a certain hardness and strength, including the whole process.

The impact of pollutants in circuit packaging on integrated circuits, which is a very important factor, will depend on these problems plaguing people, online plasma cleaning machine for these environmental pollution has exactly formed a good role.

Plasma cleaning machine, plasma cleaning, plasma equipment

A plasma is a collection of positively and negatively charged ions and electrons, and possibly some neutral atoms and molecules. Online plasma cleaning machine by setting two electrodes in a sealed container to form an electric field, with a vacuum pump to achieve a certain degree of vacuum, as the gas is more and more thin, the molecular spacing and the free movement distance of molecules or ions is also more and more long, by the electric field, they collide and form plasma, these ions are very active, its energy is enough to destroy almost all chemical bonds, Causes a chemical reaction on any exposed surface. In a certain vacuum state, plasma is used to treat the surface of the workpiece through chemical or physical action to achieve molecular level of contamination removal (general thickness of 3nm ~ 30nm), the process of improving the surface activity of the workpiece is called plasma cleaning, and the pollutants to be removed may be organic matter, epoxy resin, photoresist, oxide, micro-particle pollutants, etc.

Plasma cleaning is a kind of high precision micro-cleaning. There are oxides and micro-particles on the lead frame chip and substrate before bonding in IC packaging process. Plasma cleaning can not only remove impurities, but also improve the surface properties of the material, improve the bonding strength of the lead, and reduce the possibility of failing to weld and virtual welding.

The big difference between plasma cleaning machine and other equipment is that the cleaning force is relatively large, and it is relatively clean and environmentally friendly, and will not produce excess waste water and slag. When it comes to plasma, most people may think of chemistry, but the specific principle of the application of plasma cleaning machines is related to physics. The working situation of the plasma cleaning machine is equivalent to compression in a vacuum environment, and as the pressure continues to increase, the gap between molecules is constantly shrinking, and even more and more tends to zero. After that, the AC high-voltage oscillation AC inverter electric field emitted by the working RF source is used to convert various production process gases such as oxygen, aluminum and hydrogen into another chemically active state through a certain high temperature extrusion and other violent behaviors. Only in this state can a certain suction be formed between pollutants and pollutants, and through the mutual friction between pollutants, the pollutants are transformed into a substance with high volatility. At the end, by artificial means, all these chemicals with high volatility are transported out, so as to play a certain cleaning effect.

Plasma cleaning technology has a wide range of applications in microelectronics IC packaging, mainly used to remove surface dirt and surface etching, which can significantly improve package quality and reliability. The emergence of on-line plasma cleaning machine reduces the two times of pollution and labor costs caused by manual participation, and improves the yield and controllability of the product.