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Method for threaded mounting holes in an IHS for a FCBGA package

IP.com Disclosure Number: IPCOM000016815D
Publication Date: 2003-Jul-16
Document File: 4 page(s) / 439K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for threaded mounting holes in an integrated heatsink (IHS) for a flip-chip ball grid array (FCBGA) package. Benefits include improved reliability and improved ease of assembly.

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Method for threaded mounting holes in an IHS for a FCBGA package

Disclosed is a method for threaded mounting holes in an integrated heatsink (IHS) for a flip-chip ball grid array (FCBGA) package. Benefits include improved reliability and improved ease of assembly.

Background

        � � � � � Conventional FCBGA package data shows high solder join reliability (SJR) issues at package corners when the heatsink is applied with force (load), which increases as packages require high power dissipation. As a result, a new assembly methodology is required to ensure the thermal requirement is met while an acceptable SJR level is maintained.

        � � � � � The conventional solution is to fasten the heatsink by using a printed circuit board (PCB) as the foundation. Before loading with heatsink clip force, the PCB board is flat and the chipset solder ball is not under stress. When the heatsink clip is applied, force is placed on the chipset. The heatsink clip forces the board to flex and high stress occurs on the solder ball located at the chipset corner (see Figure 1).

        � � � � � To prevent failure, no solder ball is placed at the package corner and under the die shadow.

Description

        � � � � � The disclosed method is threaded mounting holes in an IHS on an FCBGA package without introducing stress on the second-level interconnect solder joint. Threaded mounting holes accommodate screws that directly attach the heatsink and the chipset with an IHS from the top (see Figures 2 and 3). The torque from ti...