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Method for a flip-chip package with Cu tapers and a socket with soft solder coated holes for the package and MB assembly

IP.com Disclosure Number: IPCOM000023823D
Publication Date: 2004-Mar-31
Document File: 5 page(s) / 177K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a flip-chip package with Cu tapers and a socket with soft solder coated holes for the package and motherboard (MB) assembly. Benefits include improved functionality, improved performance, and improved environmental friendliness.

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Method for a flip-chip package with Cu tapers and a socket with soft solder coated holes for the package and MB assembly

Disclosed is a method for a flip-chip package with Cu tapers and a socket with soft solder coated holes for the package and motherboard (MB) assembly. Benefits include improved functionality, improved performance, and improved environmental friendliness.

Background

         The high resistance in processor sockets must be reduced. The high currents that run through sockets require low resistances to reduce power dissipation. This relationship can be described as follows:

Power = Current2 x Resistance

         Larger power dissipations in the socket result in higher socket temperature, which causes thermal problems. Too high temperatures can cause a processor to fail.

The problem of increasing socket current to higher power CPUs is conventionally solved by increasing the number of pins, which lowers the total resistance and results in lower power dissipation. This solution is costly in terms of the actual dollar cost for the extra pins and for the real estate required for the extra pins. Additionally, the number of pins added for power dissipation may not significantly lower the resistance beyond the resistance in the core region. In this case, the effectiveness of the additional pins may not sufficiently reduce the current flowing through one region of the package and additional pins must provide an effective DC shunting.

         Conventionally, another equipment manufacturer (OEM) produced socket is utilized to provide interconnect between the flip-chip pin-grid array (FCPGA) package and MB. Adequate compressive pressure is applied to assure robust electrical and thermal performance, which is illustrated as a bolt joint (see Figure 1). An additional clamping mechanism or heatsink clips are typically used to ensure a secure connection.

General description

         The disclosed method is a modified flip-chip package with Cu tapers and a socket with soft solder coated holes. The method is combined with system enabling designs for FCBGA and/or flip-chip land-grid array (FCLGA) package/socket/motherboard system assembly. The improved interconnects and socket, provide better electrical contacts.

         The key elements of the method include:

•         Soft metal layer (such as indium solder) coated on socket holes without clamps or actuation

•         Socket with ball-grid array (BGA) balls for connecting to an existing motherboard

•         Socket with a cutout area for land-side capacitors (LSCs)

•         Modified flip-chip package with Cu tapers for connecting to the soft metal socket

•         System-enabling solutions, such as bolt joint, clamp mechanism, and heatsink clip, to apply adequate compressive pressure to assure good electrical contact between the package and the MB

Advantages

         The disclosed method provides advantages, including:

•         Imp...