Surface Mount LGA Socket With Spherical Contacts
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Solution Overview
Problem
Traditional IC sockets face mechanical and electrical limitations, such as increased terminal count, reduced terminal pitch, and signal integrity issues, which hinder their performance as IC devices advance to next-generation architectures operating above 5 GHz.
Innovation Solution
A surface mount LGA device socket with a substrate that mimics a simple beam structure, eliminating retention features that add parasitic mass and degrading signal integrity, and utilizing additive printing technology to create high-density circuit structures with fine line and feature pitches, incorporating conductive, non-conductive, and semi-conductive materials for enhanced electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional IC sockets are used with increased terminal count, then more IC terminals can be connected, but the package size increases and terminal pitch decreases causing mechanical and electrical limitations
Solution Approach 1:
The patent transitions from traditional planar PCB mounting to three-dimensional spherical contact members that protrude from the substrate surface. This dimensional change allows multiple contact points to be arranged in spherical patterns rather than flat grids, enabling higher terminal counts without increasing the footprint area of the package.
Solution Approach 2:
The invention changes the geometric parameters of contact members from flat pins to three-dimensional spheres with configurable radii. By varying the spherical radius and contact point distribution, the design achieves higher terminal density while maintaining adequate spacing for signal integrity and mechanical reliability.
2Quantity of substance
If terminal pitch is reduced to increase terminal count, then more connections are possible, but signal integrity deteriorates and contact resistance increases
Solution Approach 1:
Each spherical contact member provides locally optimized contact geometry with multiple contact points distributed across its surface. This local quality enhancement ensures that each individual contact maintains low resistance and good signal integrity even as overall terminal density increases across the package.
Solution Approach 2:
The contact members are formed as composite structures combining conductive materials with mechanical compliance features. The spherical geometry combined with spring-loaded mounting provides both electrical conductivity and mechanical tolerance, maintaining reliable contact under varying conditions despite reduced pitch.
3Ease of operation
If contact members are made longer to optimize spring properties, then mechanical compliance improves, but signal integrity decreases and self-heating increases
Solution Approach 1:
The contact members use spherical contact surfaces instead of linear extensions. This curvature provides mechanical compliance through rotational and pressure adjustments rather than requiring long axial extensions, thereby maintaining signal integrity while achieving the necessary spring properties for reliable contact.
4Quantity of substance
If insulating wall thickness is reduced to accommodate higher terminal density, then terminal pitch can be reduced, but molding difficulty increases and warpage risk increases
Solution Approach 1:
By moving contact members to three-dimensional spherical protrusions rather than planar features, the design achieves higher terminal density without requiring proportionally thinner insulating walls. The vertical dimension provides additional space for contact members while maintaining adequate wall thickness for manufacturability and structural stability.
Data Source
AI summary
A surface mount electrical interconnect adapted to provide an interface between contact pads on an LGA device and a PCB. The electrical interconnect includes a socket substrate having a first surface with a plurality of first openings having first cross-sections, a second surface with a plurality of second openings having second cross-sections, and center openings connecting the first and second openings. The center openings include at least one cross-section greater than the first and second cross-sections. A plurality of contact members are located in the socket substrate such that first contact tips are located proximate the first openings, second contact tips are located proximate the second openings, and center portions located in the center openings.