Browse Prior Art Database

Area Array Outer Lead Bond Free Form Die

IP.com Disclosure Number: IPCOM000109476D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 1 page(s) / 42K

Publishing Venue

IBM

Related People

Hernandez, B: AUTHOR [+4]

Abstract

As increasing lead counts are being considered for TAB applications, area OLB is an attractive alternative to perimeter lead placement. With the perimeter OLB TAB technology all leads are formed in an open window, and usually in a gullwing shape to accommodate mating solder pads. With the increased I/O for area array TAB it will be necessary to provide a window only at the site of the solder pad and each beam will cantilever into that window. While the surrounding polyimide area will support the leads passing between windows to the outer rows it is extremely congested in the inner rows. With the addition of local test pads it becomes increasingly difficult to form a lead in the conventional way.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Area Array Outer Lead Bond Free Form Die

      As increasing lead counts are being considered for TAB
applications, area OLB is an attractive alternative to perimeter lead
placement.  With the perimeter OLB TAB technology all leads are
formed in an open window, and usually in a gullwing shape to
accommodate mating solder pads.  With the increased I/O for area
array TAB it will be necessary to provide a window only at the site
of the solder pad and each beam will cantilever into that window.
While the surrounding polyimide area will support the leads passing
between windows to the outer rows it is extremely congested in the
inner rows.  With the addition of local test pads it becomes
increasingly difficult to form a lead in the conventional way.

      To allow for this complexity which may include leads projecting
over the window in oblique angles, a die half will be fabricated of
tool steel with hemispheres machined coincidentally with each OLB
site.  By ball-end milling or by using conventional photoprocessing
and etch techniques, the machining will be easily accomplished and
will accept leads cantilevered at any angle.  The mating half of the
die will be a suitable elastomer capable of forming the lead into the
hemisphere, imparting the correct form.

      Disclosed anonymously.