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Method for roughened socket contact surface areas

IP.com Disclosure Number: IPCOM000146359D
Publication Date: 2007-Feb-13
Document File: 3 page(s) / 550K

Publishing Venue

The IP.com Prior Art Database


Disclosed is a method for roughened socket contact surface areas. Benefits include improved performance.

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Method for roughened socket contact surface areas

Disclosed is a method for roughened socket contact surface areas. Benefits include improved performance.


      High-power microprocessor designs require very low direct current (DC) load-line resistances. The contact resistance between a socket and a package can be a significant component of the DC load line.

      Some contact designs employ surface pressure to electrically connect two separate parts. In these designs, asperities are the dominant factor in determining contact resistance. Asperities are the actual micrometer-scale contact areas between the two parts. They result from the microscopic-level roughness present in common electronic packaging materials. The more pressure that is applied, the more asperities are formed as the material surfaces are mashed together. Therefore, contact pressure is a key factor in lowering contact resistance as high pressure deforms the contacting surfaces and enables the largest overall contact area.

      Conventionally, no special effort is made to roughen the land grid array (LGA) pad surface (see Figure 1). The pad is relatively smooth. As a result, a contact with a large interface area may have difficulty sustaining the required contact pressure.

General description

      The disclosed method is LGA package pads with a purposefully roughened surface finish, which lowers the contact resistance.


      The disclosed method provides advantages, including:

•     Improved performance due to lower socket resistance

•     Improved performance due to improved socket resistance stability over time

Detailed description

      The disclosed method enables high contact pressure with roughened contact surfaces (see Figure 2). The roughness creates pressure points across the entire contact surface, ensuring a substantial amount of surface deformation under the contact load. The method increases the overall asperity count and decreases contact resistance.

      Intentional surface roughening may enabl...