Browse Prior Art Database

Three-Row Footprint Allowing Placement of Multiple Package Types

IP.com Disclosure Number: IPCOM000117922D
Original Publication Date: 1996-Jul-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Csonka-Peeren, JV: AUTHOR [+3]

Abstract

DRAM Components come in different types of packaging, for instance, two common form factors are 300 mil SOJ and 300 mil TSOPII. The footprint, or "land pattern", of a component defines the size and shape of the copper pads onto which the component leads are soldered. A three-row footprint shown in the Figure which can be populated with either of these packages. In an effort to reduce the total tip-to-tip size of this multi-footprint, Row 1 is "shared" between the SOJ and TSOPII components. The intention of this hybrid footprint is to allow the flexibility of populating with either one of these form factors, while economizing on the real-estate required.

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Three-Row Footprint Allowing Placement of Multiple Package Types

      DRAM Components come in different types of packaging, for
instance, two common form factors are 300 mil SOJ and 300 mil TSOPII.
The footprint, or "land pattern", of a component defines the size and
shape of the copper pads onto which the component leads are soldered.
A three-row footprint shown in the Figure which can be populated with
either of these packages.  In an effort to reduce the total
tip-to-tip size of this multi-footprint, Row 1 is "shared" between
the SOJ and TSOPII components.  The intention of this hybrid
footprint is to allow the flexibility of populating with either one
of these form factors, while economizing on the real-estate required.

      The Figure shows the land pattern for a three-row footprint
which can accommodate either a 300 mil SOJ or 300 mil TSOPII
component.  Pads in Row 1 can be used by either package, while those
in Row 2 and Row 3 are optimized to accommodate only the SOJ leads
and the TSOPII leads, respectively.

      The required length and width of the copper pads for Row 3, the
"TSOPII-only" row, is 60 mil and 22 mil, respectively, less than that
required for Row 2, the "SOJ-only" row, which is 70 mil and 24 mil,
respectively.  A piece of etch of 7 mil width is used to join these
two rows.

      Pads in Row 1 can be used with either the SOJ or TSOPII
package.  These pads are 70 mil in length and 24 mil in width, longer
and wider than require...