The application of NTC thermist chips in copper and silver keys

　　The copper and silver wire bonds are the process of paste the chip electrode on the packaging base, and use the metal wire to connect the chip electrode (pad) and the corresponding electrode key on the lead frame. Under normal circumstances, gold wire is used as a key to the integrated circuit as the main lead material. However, the price of gold silk is expensive, resulting in excessive packaging costs. With the development of packaging technology, the golden -key combination technology can no longer fully meet the high performance requirements of smaller, thinner, faster, and higher reliability. Copper wire is low in price and excellent performance of machinery, electrical, and thermal science. The combination of copper wire bonds and silver wire bonds has replaced the gold wire bonds to occupy the main market.

　　Copper filament

　　In recent years, the copper wire bonding has gradually replaced the golden bond. The process of the copper filament key is much more stricter than the gold wire bond. Formation of shape and inter -metal compounds (IMC, and InternetAllic Compound). Although the cost of copper wire is about 20%of the golden silk, the additional cost of its process is higher. For example, copper wire is not easy to form inter -metal inter -compounds. The thickness of the aluminum pads is at least 0.8 μm, and the pressure during the key is 30%larger than the gold wire. In order to solve the above problems and improve the reliability of copper wire bonds, most factories will adopt methods such as increasing the pads to improve the pad structure and the use of higher ultrasound frequency.

　　In high-temperature storage tests, the growth rate of the copper-aluminum bonding metal compounds is slower than that of the gold-aluminum bond, which indicates that the combination of copper-aluminum bonds is slow, and its bonding strength is not easy to change. At high temperatures, the growth rate of the metal intervertebral compounds of the gold-aluminum bonding is always accompanied by the generation of Ken Dal's empty cavity, resulting in a reduction in the strength of the bond. From this perspective, the reliability of copper filament bonds is higher. However, in the high humidity storage test, the metal intervertebral compounds of copper aluminum bonds are vulnerable to chemical corrosion or electrochemical corrosion of halogen (such as chlorine CL, bromo) in plastic fertility, which transforms copper-aluminum metal compounds into copper and aluminum aluminum, aluminum, aluminum and aluminum Oxide.

　　Silver shit

　　Silver wire bonds mainly use wedge -shaped welding for NTC thermist chip bonds, that is, the main key combination method of the second solder joint.

　　In recent years, the silver wire bonds have not been encapsulated by dynamic random access to memory (DRAM, Dynamic Random Access Memory) packaging and thin small size packaging (TSOP, Thin Small Outline Package), but also began to be applied to digital logic circuits (DLC Digital logic circuit). On the one hand, the cost of silver wire is lower than gold wire; on the other hand, the craft window of the silver wire is wider than the copper wire, and the reverse key combined can be used, which makes the silver wire bonds widely used in thin keys welding welding welding Disk, crack bond pad pads and pads and pads are connected.

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