Performance and reliability of a cavity down tape BGA package

As the demand for greater I/O has increased, so has the interest in ball grid array packaging. It is well recognized in the packaging industry that as the pin counts increase above 208, BGA packages become more attractive due to their small form factor and ease of board attach. However, along with the general trend for higher I/O, an increasing percentage of ICs are also running at over 200 MHz and 4 W of power. These IC requirements surpass the capability of standard QFP and PBGA packages. To satisfy this demand, there has been a major push for high performance BGA packages which are considerably more cost effective than ceramic package alternatives. Tape BGA packages provide an excellent cost/performance solution in this market segment and are gaining a great deal of attention. With the fine line capability of flexible circuits (down to 25 μm lines and spaces), the wire bond fingers can be moved very close to the die. This enables die shrinkage in pad limited die and reduces wire length, which is often the main source of package self inductance. Excellent thermal properties are achieved by directly attaching the die to a thermally conductive copper stiffener or heat spreader. The copper CTE also matches closely with that of the board to maximize thermal cycle reliability. This product can be provided at a competitive price due to the minimization of materials and a simplified production process. The result is a low cost, high performance package with excellent reliability. This paper discusses the electrical and thermal performance of this package along with the reliability