Land grid array interconnect formed with discrete pads

Patent metadata

Field	Value
Publication number	US-9769924-B2
Application number	US-201414323048-A
Country	US
Kind code	B2
Filing date	Jul 3, 2014
Priority date	Aug 4, 2011
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

A land grid array (LGA) includes a grid array of metal pads plated directly onto a printed circuit board, and a discrete metal pad soldered to each of the plated metal pads in the grid array. Each discrete metal pad has an exposed contact surface after soldering, and a thickness of each discrete metal pad is selected as a function of location in the grid array so that the discrete pads provide a locus of exposed surfaces having greater flatness than the printed circuit board.

First claim

What is claimed is:

1. A land grid array, comprising: a grid array of metal pads plated directly onto a printed circuit board having a plurality of conductive vias, wherein the plated metal pads cover the conductive vias; and a discrete metal pad soldered to each of the plated metal pads in the grid array with a layer of solder between the plated metal pads and each discrete metal pads and each discrete metal pad, wherein each discrete metal pad is positioned directly over one of the plated metal pads, wherein each discrete metal pad is positioned directly over one of the plated metal pads, wherein each discrete metal pad has an exposed contact surface after soldering, and wherein a thickness of each discrete metal pad is selected as a function of location in the grid array so that the discrete pads provide a locus of exposed surfaces having greater flatness than the printed circuit board.

2. The land grid array of claim 1 , wherein the discrete metal pads have a base metal core plated with one or more metals.

3. The land grid array of claim 1 , further comprising:
a via in a plurality of the plated metal pads, wherein the discrete metal pads cover the via.

4. The land grid array of claim 1 , wherein the exposed contact surface of the discrete metal pads is plated with gold for contact with a surface mounted component.

5. The land grid array of claim 1 , wherein the discrete pads have a copper core plated with another metal, and wherein the thickness of the copper core varies among the individual discrete pads.

6. The land grid array of claim 5 , wherein the copper core is plated on all sides with nickel.

7. The land grid array of claim 5 , wherein the discrete pads have a tin plated surface that is soldered to the plated copper pad.

Assignees

• Lenovo Entpr Solutions Singapore Pte Ltd

Inventors

• Pymento Larry G
• Sass Tony C
• Wormsbecher Paul A

Classifications

• H05K1/09

  Use of materials for the {conductive, e.g. } metallic pattern · CPC title

• H05K2201/10719

  Land grid array [LGA] · CPC title

• H05K3/3436

  having an array of bottom contacts, e.g. pad grid array or ball grid array components · CPC title

• Y10T29/49155

  Manufacturing circuit on or in base · CPC title

• H05K3/4015 Primary

  using auxiliary conductive elements, e.g. pieces of metal foil, metallic spheres · CPC title