As the chip carrier of integrated circuits, lead frame is a key structural component that uses bonding materials (gold wire, aluminum wire, copper wire) to realize the electrical connection between the internal circuit lead end of the chip and the external lead to form an electrical circuit. It plays a bridge role in connecting with external wires. Lead frame is required in most semiconductor integrated blocks and is an important basic material in the electronic information industry.
Function
As the chip carrier of integrated circuits, lead frame is a key structural component that uses bonding materials (gold wire, aluminum wire, copper wire) to realize the electrical connection between the internal circuit lead end of the chip and the external lead to form an electrical circuit. It plays a bridge role in connecting with external wires. Lead frame is required in most semiconductor integrated blocks and is an important basic material in the electronic information industry.
Product Introduction
There are TO, DIP, ZIP, SIP, SOP, SSOP, TSSOP, QFP (QFJ), SOD, SOT, etc. It is mainly produced by die stamping and chemical etching. The raw materials used for lead frames are: KFC, C194, C7025, FeNi42, TAMAC-15, PMC-90, etc. The selection of materials is mainly based on the performance required by the product: (strength, electrical conductivity and thermal conductivity).
Copper alloy lead frame material
Characteristics
The copper alloys used for lead frames are roughly divided into copper-iron series, copper-nickel-silicon series, copper-chromium series, copper-nickel-tin series (JK--2 alloy), etc. Ternary and quaternary multi-system copper alloys can achieve better performance and lower cost than traditional binary alloys. Copper-iron alloys have the most grades and have good mechanical strength, stress relaxation resistance and low creep. They are a good type of lead frame material. Due to the needs of lead frame production and packaging applications, in addition to high strength and high thermal conductivity, the material is also required to have good brazing performance, process performance, etching performance, oxide film bonding performance, etc. Materials are developing towards high strength, high conductivity and low cost. A small amount of multiple elements are added to copper to improve the alloy strength (making the lead frame less likely to deform) and comprehensive performance without significantly reducing the conductivity. Materials with a tensile strength of more than 600Mpa and a conductivity greater than 80% IACS are research and development hotspots. Copper strips are required to have high surface, precise plate shape, uniform performance, and thinning strip thickness, gradually thinning from 0.25mm to 0.15mm and 0.1mm, and ultra-thin and special-shaped 0.07-0.07mm.
R&D dynamics
According to the alloy strengthening type, it can be divided into solid solution type, precipitation type, and precipitation type. From the perspective of material design principles, lead frame materials are almost all precipitation-strengthened alloys, and are designed using a variety of strengthening methods, mainly deformation strengthening, solid solution strengthening (alloying strengthening), grain refinement strengthening, and precipitation strengthening. Adding an appropriate amount of rare earth elements can increase the conductivity of the material by 1.5-3% IACS, effectively refine the grains, increase the strength of the material, improve toughness, and have little effect on conductivity. Research is conducted on the combination of work hardening and solid solution hardening, solid solution-aging hardening, and composite strengthening to improve material performance.
