I. Basic Structure of Cover Tape

A typical cover tape is not composed of a single material but rather constitutes a multi-layer composite structure. It typically consists of three components: a base film layer, an intermediate bonding layer (optional), and a sealing layer (adhesive layer).

1. Base Film Layer

The base film serves as the “skeleton” of the cover tape, determining its mechanical strength and transparency.

Common Materials: PET (polyester film) is the most prevalent choice.

Characteristics: It possesses extremely high tensile strength, heat resistance, and excellent transparency. Transparency is critical because it enables the Automated Optical Inspection (AOI) systems at semiconductor assembly and test facilities to visually inspect the condition of the chips within the carrier tape pockets without the need to unseal the tape.

2. Sealing Layer / Adhesive Layer

This constitutes the core of the cover tape, directly determining its sealing performance and the stability of its peel force.

Heat-Activated Type: The primary components are typically polyolefins or their copolymers. Under specific conditions of temperature and pressure, the adhesive layer softens and fuses with the edges of the carrier tape.

Pressure-Sensitive Type: This type relies on pressure to generate adhesion and is composed of acrylic-based adhesives.

3. Anti-static Treatment Layer

Since semiconductor devices are extremely sensitive to electrostatic discharge (ESD), both the inner and outer surfaces of the cover tape typically undergo anti-static treatment.

Additives: Commonly used additives include conductive polymers, surfactants, or metal oxide nanocomposites.

Function: To ensure that the electrostatic voltage generated during the peeling of the cover tape is maintained within an extremely low range (typically less than 10V), thereby preventing electrostatic breakdown of the chips.