Browse Prior Art Database

Two-Piece Land Grid Array Socket Assembly

IP.com Disclosure Number: IPCOM000083107D
Publication Date: 2005-Feb-28
Document File: 3 page(s) / 908K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a land grid array (LGA) socket with a polymer housing and a through hole mount (THM) metal casting, which can be assembled and separated. Benefits include improving the reflow process, prevention of overheating surrounding small components due to the metal thermal mass and cost saving in rework of the LGA socket.

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Two-Piece

Land

Grid Array Socket Assembly

Disclosed is a method for a land grid array (LGA) socket with a polymer housing and a through hole mount (THM) metal casting, which can be assembled and separated. Benefits include improving the reflow process, prevention of overheating surrounding small components due to the metal thermal mass and cost saving in rework of the LGA socket.

Background

There is a large thermal mass associated with the current LGA socket. This large thermal mass is responsible for the following issues:

§         Difficulty in reflowing the LGA socket during the PCB assembly process, where the large metal casting causes it to heat up slowly.

§         Difficulty in performing rework on the LGA socket because of the heat absorbed by the metal casting. Higher temperatures and heating times are required.

§         A non-equilibrium heating effect causing secondary heating on the surrounding components. This causes thermal shock, warpage, and other thermal and mechanically-induced defects. Current data indicates that the secondary heating effect on the surrounding BGA solder ball can reach as high as 196oC, where the center solder ball on the LGA is at 200oC for the rework process.

§         The large metal mass and stack up of the thermal solution creates the need for more solder joins to strengthen the assembly.

Currently, difficulty in the reflow process is compensated for by prolonging the reflow soak time and increasing the heating temperature; however, this slows production. In addition, for rework on the LGA BGA socket, there is no solution to prevent the secondary heating effect on other surrounding components.

General Description

The disclosed method uses a polymer housing with a solder ball array and contact pins
(see Figure 1). The THM metal casting holds down the polymer housing with the spring built in the metal casting. The top cover of the metal casting is used to compress the micro-processor package onto the pin arrays, and to produce the mechanical and electrical connections. The metal latch arm at the open end of the...