Current Issue An Independent Journal Dedicated to the Advancement of Chip - Scale Electronics July 2001 Email the editor

Mark Bird Contributing Editor

Leadframe-based CSPs are one of the fastest growing package formats in the marketplace, as estimated unit volumes in Table 1 indicate. In addition, there does not seem to be an end to this growth anytime soon.

The activity level of leadframe-based CSPs is mirrored in the JEDEC JC-11 committee with new variations and families. (The history of the standardization of this package is shown in Table 2.)

The thermally enhanced, cavity-up dual-inline terminal lead CSP-MO-XXX is in balloting and will be published by the end of this year.

The latest package registration revision is available on the Web at www.jedec.org for downloading without charge.

The package sizes range from 1.00 x 1.50 mm to 12.00 x 12.00 mm with a leadcount ranging from 4 to 80. This registration has 0.80, 0.65 and 0.50 mm terminal pitches and two profile heights: V (0.80

The basic construction of these lead-frame CSPs is shown in the cross-section (see figure).

The package starts with an etched or stamped leadframe, followed by the die being mounted and ball bonded just like a conventional peripheral leadframe-style SOIC or PQFP. The package is then overmolded using standard molding compounds. The final terminal finish can either be a solder plate or some other lead-free plated finish. The construction of this package would also allow pre-plated leadframes to be used. The package is then singulated by sawing or punching.

This basic package takes full advantage of the infrastructure of the peripheral leadframe packages; therefore, it will be able to ramp up very quickly and perhaps more cost effectively than other CSP alternatives. The final package is very rugged, and some suppliers report being able to classify this package as being a Level 1 or 2 for J-STD-020A Moisture Sensitivity.

This illustration shows a basic cross-section of a leadframe CSP.

Designed for Lower Pincounts

This variety of packages is designed primarily to meet the needs for lower pincount packages. Since there are no peripheral leads, bent leads and coplanarity are not an issue.

The result of this activity in 2001 will be the rise of new styles of CSPs with quad, rectangular and dual-inline versions. The present MO-220 will continue to have variations added, and registration numbers will also be added for the new configurations. JC-11 has its work cut out for it to keep pace with the growth of this new, high-volume CSP.