The function and types of cover tapes
1. Primary Functions
- Component Retention: The cover tape acts as a lid, ensuring that tiny components (like ICs, resistors, or capacitors) stay securely within their designated pockets during shipping and handling.
- Contamination Protection: It provides a barrier against dust, moisture, and debris that could damage the sensitive surfaces of the semiconductor.
- Electrostatic Discharge (ESD) Protection: High-quality cover tapes are treated with anti-static or dissipative coatings to prevent static buildup, which can instantly destroy microchips.
2. Key Technical Specifications
To ensure a smooth automated assembly process, cover tapes must meet specific criteria:
- Peel Force: This is the most critical parameter. The force required to peel the tape back during the “pick and place” process must be consistent (typically between 0.1N to 1.3N). If it’s too tight, the machine might jerk; if too loose, the tape might delaminate prematurely.
- Transparency: Most cover tapes are transparent or translucent to allow optical inspection systems to verify the presence and orientation of the component inside the pocket.
- Tensile Strength: It must be strong enough to be pulled at high speeds by automated feeders without tearing.
3. Types of Sealing Methods
There are two main ways the cover tape adheres to the carrier tape:
- Heat Activated (HAA): The adhesive is activated by a heated sealing bar. This provides a very stable bond but requires precise temperature control.
- Pressure Sensitive (PSA): This tape uses an adhesive that bonds simply by applying pressure. It is easier to use but can be more sensitive to aging and temperature fluctuations during storage.