An Independent Journal Dedicated to the Advancement of Chip - Scale Electronics July - August 2000 Email the editor

`Since these [leadframe-based] packages contain no peripheral leads, lead bend and coplanarity are not an issue.' Leadframe-based CSPs did not seem to be a reality until they appeared in the JEDEC JC-11 Standardization balloting process last year. The first family of these packages was approved in the JC-11 committee meeting in January 2000 as MO-220/A. The package registration was published in February, and is now available at www.jedec.org Website in Acrobat PDF format for free downloading.

By Mark Bird Contributing Editor

The MO-220 family consists of 70 different variations of a Quad Terminal Lead CSP family that is cavity up and thermally enhanced.

The package sizes range from a low of 3 x 3 mm to a high of 8 x 8 mm with a lead count ranging from 4 to 56. This registration has 0.80, 0.65, and 0.50 mm terminal pitches and two profile heights: V (0.80(A(1.00 mm) and W (0.65(A(0.80 mm).

Anvil or Saw Singulation

This registration allows the package to be singulated using either the anvil or saw method. (The difference in the final package is shown in Figures 1 and 2.)

Figure 1. Leadframe-based CSP, which has been anvil singulated is at left, while saw singulated package is at right.

The package starts with an etched or stamped leadframe. The die is then mounted and ball bonded just like a conventional peripheral leadframe style SOIC or plastic quad package.

The package is then overmolded using standard molding compounds. The final terminal finish can either be a solder plate or some other plated finish. The construction of this package will also allow pre-plated leadframes to be used. The package then is singulated using either anvil or saw.

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 maybe more cost effectively than other CSP alternatives.

Figure 2. Basic construction of a leadframe CSP

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 variety of package is primarily aimed at meeting the needs of lower pin count applications. Since these packages contain no peripheral leads, lead bend and coplanarity are not an issue.

Inputs from the JC-11 JEDEC committee indicate that more variations will be forthcoming for this package style. JEDEC members in the memory business have requested that rectangular versions be added. Other companies have requested adding non-thermally enhanced versions.

Still another group has asked to add dual inline (two sided) versions of these packages, which may or may not have thermal enhancements.

New Styles

The result of this activity in 2000 will be the rise of new styles of CSPs with quad, rectangular, and dual inline versions.

The present MO-220 will have variations added, and at least two new registration numbers will be given for the new configurations.

JC-11 has its work cut out for it in keeping pace with the standardization of this new high volume CSP.