What is a lead frame

Lead frame is the basic material of semiconductor packaging and the chip carrier of integrated circuits. It uses bonding materials (gold wire, aluminum wire, copper wire) to realize the electrical connection between the lead-out end of the chip's internal circuit and the outer lead, forming a key structural component of the electrical circuit. It plays the role of a bridge connected with external wires, and its main function is to play the role of circuit connection, heat dissipation, and mechanical support.

Lead frame composition

The lead frame is mainly composed of two parts: die paddle and lead finger. As a chip carrier for integrated circuits, it uses bonding materials (gold wire, aluminum wire, copper wire) to realize the electrical connection between the lead-out end of the chip's internal circuit and the outer lead, forming a key structural component of the electrical circuit. it acts as a bridge connecting with external wires.

Lead Frame Material

In integrated circuits, lead frames and packaging materials play a role in fixing chips, protecting internal components, transmitting electrical signals and dissipating heat from components. Lead frame material should meet the following characteristics:

1.Good thermal and electrical conductivity, which can reduce the adverse effects caused by capacitance and inductance, and is also conducive to heat dissipation;

2.Low coefficient of thermal expansion, good matching, brazing, corrosion resistance, heat resistance and oxidation resistance, good electroplating;

3. Sufficient strength, stiffness and formability. Generally, the tensile strength is greater than 450MPa, and the elongation is greater than 4%;

Good flatness and small residual stress;

Easy to punch and process without burrs;

The cost is low and can meet the requirements of large-scale commercial application.

Copper alloys widely used at present include: copper-iron-phosphorus, copper-nickel-silicon, copper-chromium-zirconium, copper-silver, copper-tin and other alloy systems; The ideal lead frame material is a high-conductivity, high-strength, high-function material with a tensile strength of more than 600MPa, a conductivity of more than 80%, and an anti-softening temperature greater than 500°C.

Lead Frame Surface Treatment - Plating

In order to ensure the chip mounting/bonding performance in the packaging process, special surface treatment is required for the lead frame. According to the different grasping methods of the lead frame plating area, it is divided into three types: crawler plating (tank chain), platen plating and wheel plating. Common lead frame plating elements include gold, silver, palladium, nickel, etc.

Application of LANScientific INSIGHT in Connector Inspection

With the development of integrated circuits in the direction of high density, miniaturization, and multi-function, the thickness of the lead frame material has been reduced from 0.25mm to 0.15mm and 0.125mm. It has now been reduced to 0.08mm, or even below 50μm. Therefore, the thickness and performance requirements of the material coating are higher.

INSIGHT is very suitable for different types of lead frame coating thickness detection and composition analysis, helping the semiconductor packaging industry to effectively improve productivity and ensure compliance with industry standards to avoid cost waste.

Figure: Sample Test