Low-Profile LGA Socket Pins With Serpentine Spring Shielding
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Solution Overview
Problem
Existing LGA sockets fail to meet high-frequency performance and reliability requirements, experiencing capacitive or inductive coupling leading to undesirable crosstalk and mechanical damage, while pogo-pin alternatives are unsuitable due to excessive height and cost.
Innovation Solution
The development of socket pins with a serpentine spring design and a printed circuit board-based housing that reduces crosstalk through localized shielding, maintains mechanical robustness, and supports high-speed data transmission, while being cost-competitive with existing designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cantilever beam approach is used for socket pins, then the pins can provide contact force against integrated circuit component lands, but the pins are susceptible to mechanical damage and mishandling
Solution Approach 1:
The socket pin is segmented into multiple parts: a cylindrical contact portion, a serpentine spring portion, and a mounting portion. This segmentation allows each part to perform its specific function optimally - the cylindrical contact portion provides robust mechanical strength, the serpentine spring portion provides flexibility and contact force, and the mounting portion provides secure attachment to the PCB
Solution Approach 2:
The socket pin combines different material properties in a composite structure - the cylindrical contact portion uses a stiff material for mechanical strength, while the serpentine spring portion uses a more flexible material for elasticity. This composite approach resolves the contradiction between needing mechanical strength and needing flexibility for contact force
2Reliability
If existing LGA socket designs are used, then the structure is simple and cost-effective, but they fail to meet high-frequency performance requirements and exhibit crosstalk
Solution Approach 1:
The housing incorporates localized shielding structures - metallic shields positioned between adjacent pins - that provide electromagnetic interference protection only where needed. This local quality approach reduces crosstalk for high-frequency signals without requiring complete redesign of the entire socket structure, thus maintaining cost-effectiveness while improving high-frequency performance
Solution Approach 2:
Metallic shield structures are introduced as intermediary elements between adjacent signal pins. These shields act as mediators that block electromagnetic coupling between pins, reducing crosstalk. The shields are strategically positioned to provide EMI protection without significantly increasing overall device complexity
3Reliability
If pogo-pin alternatives are used, then reliability can be improved, but the height becomes excessive and cost increases
Solution Approach 1:
The serpentine spring portion provides dynamic elasticity, allowing the pin to flex and maintain optimal contact force with the integrated circuit component land. This dynamic capability provides reliable electrical connection similar to pogo-pins, but within a more compact height constraint because the spring mechanism is integrated into the pin body rather than requiring a separate long compression structure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides high-speed data transmission exceeding 56 Gb/s with minimized crosstalk, improved mechanical reliability, and reduced stack height, offering a cost-effective interconnect solution for enterprise-class systems.
Implementation Method 1
a serpentine spring portion (308) positioned between and attached to the top contact portion (304) and the bottom contact portion (312)
Data Source
AI summary
Land grid array (LGA) sockets with low-profile housings and stamped cylindrical pins are disclosed. Each pin includes a top contact portion, a bottom contact portion, and a serpentine spring portion that compresses along the vertical axis. In some embodiments, a bent electrically conductive strip provides a shorter electrical path to support high-speed data transmission. In other embodiments, the pin comprises a stub that contacts a pin hole plating layer to provide a shorter electrical path. The pins may be formed from beryllium copper and plated with palladium-gold. The socket housing, formed from printed circuit board laminate layers, defines cavities that receive and constrain the pins to limit movement and prevent damage. Localized ground and power structures, including plated-through holes and shielding vias, reduce crosstalk. The low-profile socket designs enhance signal and power integrity while enabling cost-effective manufacturability through progressive stamping and laminate-based assembly.