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V-Shaped Land Grid Array Contact Beam Design

IP.com Disclosure Number: IPCOM000023837D
Publication Date: 2004-Mar-31
Document File: 3 page(s) / 120K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a land grid array (LGA) contact beam with two bending sections; the two sections are shaped like a horizontal "V". Benefits include reducing both handling damage and contact shorting.

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V-Shaped Land Grid Array Contact Beam Design

Disclosed is a method for a land grid array (LGA) contact beam with two bending sections; the two sections are shaped like a horizontal “V”. Benefits include reducing both handling damage and contact shorting.

Background

Currently, the LGA stamped-metal contact design requires a long deflection (i.e. compliancy) in order to mate with an organic substrate that is not very flat. This long deflection range requires a relatively long contact beam length; however, the longer beam creates the following problems (see Figures 1 and 2):

§         It is relatively easy to bend or damage the beam. The lower spring rate somewhat negates the advantages of the longer deflection range, since the spring must deflect more to reach the minimum normal force.

§         Each contact beam has to extend over the next cell, which increases the probability of electrical shorting.

§         Longer contact displacement (i.e. wiping) requires a large pad size and increases the chance of the contact the missing pad.

The current state of the art solves these problems by:

§         Folding the beam so the overall beam length is shorter, but the effective beam length is equivalent to the POR design.

§         The contact mating point is right on top of the contact cell, not overlapping the adjacent cell as in POR design. The risk of electrical shorting is far more remote.

§         The contact tip is bent down further to increase its resistance to handling damage.

§         The contact point moves toward one direction as the primary beam deflects first. Then, as the secondary beam is deflecte...