Browse Prior Art Database

Method for an SLBGA

IP.com Disclosure Number: IPCOM000100613D
Publication Date: 2005-Mar-15
Document File: 2 page(s) / 109K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a spring-loaded ball grid array package (SLBGA). Benefits include improved functionality, improved performance, and improved reliability.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 54% of the total text.

Method for an SLBGA

Disclosed is a method for a spring-loaded ball grid array package (SLBGA). Benefits include improved functionality, improved performance, and improved reliability.

Background

      Conventional implementations for flip-chip ball grid arrays (FCBGAs) use solder balls as the first-level interface. This approach requires the use of under-fill to reduce coefficient of thermal expansion (CTE) mismatches between the adjoining surfaces. Despite the use of under-fill, open joints are possible due to cracks in the first-level interconnection between the ball and die (see Figure 1).

      The first-level interconnects in a FCBGA are created via bumping the active side of the silicon die and reflow soldering the bumped die to an interposer. The CTE mismatch between the die and interposer creates stress and may result in open joints during the package life cycle. Underfill is used to reduce this stress.

      Conventional methods cannot be reworked. Solder-joint cracking causes failure.

General description

              The disclosed method attaches the inactive side of the silicon die to an outer case, which may be a metallic or a nonhydroscopic material. If the active silicon die faces downward, it is clamped/fixed to a spring-bed BGA interposer to form the first level interconnect between the die and the springs. The package structure is soldered to a board via reflow to form the second-level interconnect.

Advantages

              The disclosed method provides advantages, including:

•             Improved functionality due to providing spring-loaded first...