Tape Automated Bonding (TAB) - Page 2 of 2

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After gang bonding, the die, bonds, tape leads, and part of the tape are covered with an encapsulant, which provides mechanical and chemical protection to the circuit after its curing.  The die is then electrically tested, after which the useable part of the tape is punched from the frame for assembly into the final application.

Fig. 2.  Examples of Tape Automated Bonding Equipment

Tape Automated Bonding offers the following advantages: 1)  it allows the use of smaller bond pads and finer bonding pitch; 2) it allows the use of bond pads all over the die, not just on the die periphery, and therefore increases the possible I/O count of a given die size; 3) it reduces the quantity of gold needed for bonding; 4) it limits variations in bonding geometry; 5)  it has a shorter production cycle time; 6) it results in better electrical performance (reduced noise and higher frequency); 7) it allows the circuit to be physically flexible; and 8) it facilitates multi-chip module manufacturing.  

Tape Automated Bonding, on the other hand, has the following disadvantages:  1) time and cost of fabricating the tape; 2) the need to 'tailor-fit' the tape pattern after each die; and 3) capital expense for TAB equipment since TAB manufacturing requires a set of machines different from those used by conventional processes. 

Thus, Tape Automated Bonding is a better alternative to conventional wirebonding if very fine bond pitch, reduced die size, and higher chip density are desired.  It is also the technique of choice when dealing with circuits that need to be flexible, such as those that experience motion while in operation, e.g., printers, automotive applications, folding gadgets, etc. Tape Automated Bonding is generally more cost-effective for use in high-volume production, since returns on the time and cost of developing the tape will be maximized under this situation.

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