TAB bonding, which stands for Tape-automated bonding, is a process used to attach bare semiconductor chips (dies) onto a flexible circuit board (FPC) by connecting them to fine conductors in a polyamide or polyimide film carrier [1]. This bonding technique is commonly used in the electronics manufacturing industry, particularly for achieving chip-on-flex (COF) assembly .
Process:
TAB bonding involves placing the bonding sites of the semiconductor die, usually in the form of bumps or balls made of gold, solder, or anisotropic conductive material, onto fine conductors on the tape .
The bumps or balls can be located either on the die or on the TAB tape .
TAB compliant metallization systems include various combinations of materials such as gold-plated copper, gold or tin bumped tape areas, and solder-plated tape areas .
The tape, which may already contain the application circuit of the die, is moved to the target location, and the leads are cut and joined to the chip as necessary .
Joining methods used with TAB bonding include thermocompression bonding, thermosonic bonding, and other techniques .
After bonding, the bare chip may be encapsulated with epoxy or a similar material .
Merits of TAB bonding:
All chip interconnections are made during one bonding process, distinguishing TAB from wire bonding .
TAB bonding can be highly automated and fast, making it suitable for high-volume electronics production.
It produces lightweight and thin assemblies due to the thin substrate and minimal glob topping, which is beneficial in applications where small weight and thinness are desired .
In some cases, additional packaging may not be necessary, potentially replacing metallic lead frames in certain packaging approaches .
Challenges of TAB bonding:
Specific machinery is required for TAB manufacturing .
The chips need to have bumps on the input/output (IO) pads or bumps need to be on the tape, and the bumps and metals on the chip and tape must be compliant to ensure reliability in various environmental conditions .
The speed advantage of TAB bonding has diminished with the development of flip chip manufacturing, which also enables simultaneous bonding of all IOs of the die .
