Eutectic welding is also called low melting point alloy welding.The basic characteristics of eutectic alloys are that two different metals can form alloys in a certain weight ratio at a temperature far lower than their respective melting points.In microelectronic devices,the most commonly used eutectic welding is to weld the chip to a gold-plated base or lead frame,i.e."gold core eutectic welding".

　　The process of eutectic welding is that under a certain temperature and pressure,the chip is lightly rubbed on the gold-plated base to wipe off the unstable oxide layer at the interface,so that the contact surface is melted and a liquid phase is formed by two solid phases.After cooling,when the temperature is lower than the "gold core eutectic point",the crystal forms formed by the liquid phase combine with each other to form a mechanical mixture,i.e."gold core eutectic crystal",so that the chip is firmly welded on the base,and good low resistance ohmic contact is formed.

　　Advantages of eutectic welding:

　　Eutectic alloy technology has been widely used in electronic packaging industry,such as chip to substrate bonding,substrate to shell bonding,shell sealing cap and so on.Compared with traditional epoxy conductive adhesive bonding,eutectic welding has the following 　　characteristics:

　　·High thermal conductivity;

　　·Low resistance;

　　·Heat transfer block;

　　·High reliability;

　　·The shear force is large after bonding;

　　·Good heat dissipation.

　　Eutectic welding must be used for power devices with high heat dissipation requirements.Eutectic welding is to use the characteristics of eutectic alloy to complete the welding process.