Socket
A socket, in electronics and computing, is a specialized type of electrical connector designed to provide a removable interface between an integrated circuit (IC) or processor and a printed circuit board (PCB) or test system [1]. These components serve as critical jigs or fixing tools that allow for the temporary mounting, connection, and easy insertion and removal of semiconductor packages without requiring permanent soldering [3]. Sockets are fundamentally defined by their role in enabling interconnection, and they are broadly classified by their application, such as for production, testing, or burn-in, and by their mechanical design, which dictates how they interconnect with the component [2][3]. Their use is essential across the electronics industry, as they protect delicate and expensive components from heat damage during soldering, facilitate testing and inspection, and allow for component upgrades or replacements [3]. The key operational characteristic of a socket is its provision of a reliable, yet non-permanent, electrical and mechanical connection. This is achieved through a contact interface—often a set of spring-loaded pins, pads, or contacts—that mates with the terminals, lands, or balls on the IC package [2]. The performance and durability of this interface are heavily influenced by the contact plating material, with contact resistance being a primary metric for evaluation [3]. Two major mechanical types for central processing unit (CPU) sockets are the Pin Grid Array (PGA), where pins are on the processor and the socket contains holes, and the Land Grid Array (LGA), where lands are on the processor and spring-loaded pins are in the socket [2]. For other package styles, such as Ball Grid Array (BGA) or Chip Scale Package (CSP), specialized sockets are designed to fit specific package sizes and pitches, which can range from 0.5mm to 1.27mm [3]. The applications of sockets are diverse and integral to modern electronics manufacturing and maintenance. In production, they are used for connecting devices internally, for board-to-board connections, and in applications ranging from automotive electrical equipment to connecting LCDs and HDDs [1]. Their most critical role is in the semiconductor back-end process, where they are categorized as IC sockets for inspection [3]. These are specifically divided into burn-in sockets, used for temperature and voltage load tests, and test sockets, used for final product inspections [3]. These sockets act as the vital interface between the IC and automated test equipment (ATE) or burn-in systems, enabling repeated testing cycles [3]. Beyond hardware, the term "socket" also extends to software, referring to application programming interfaces (APIs) for network communication, such as the Socket.IO library for real-time web client-server communication [2]. This combination of hardware and software meanings underscores the socket's foundational role in both physical interconnection and digital data exchange.
Overview
A socket, in electrical and electronic engineering, is a type of connector designed to provide a removable interface between two components or subsystems. It functions as the receptacle or female component in a mated pair, typically receiving a corresponding male plug or header to establish electrical continuity [6]. This fundamental design principle enables modularity, serviceability, and flexibility across countless applications, from internal board-to-board connections within a single device to the interconnection of entire systems. The performance of a socketed connection is governed by multiple factors, including contact geometry, insertion force, and the mechanical alignment features that ensure proper mating. As noted earlier, the contact plating material is a critical consideration, directly influencing the interface's performance and durability, with contact resistance serving as a primary evaluation metric.
Socket Connectors and Pin Headers
The broad category of socket connectors encompasses a wide array of form factors and specifications tailored for specific uses. A common and versatile implementation is their use in combination with pin headers, often referred to as plugs. These mated pairs facilitate a wide range of connections, both between separate devices and for internal connections within a single assembly [6]. The socket in this configuration typically features a molded plastic housing containing a series of conductive receptacles, each designed to accept and grip a single pin from the header. This system allows for the repeated connection and disconnection of printed circuit boards (PCBs), peripheral modules, or cabling without requiring permanent soldering. Beyond data and signal transmission, these connector systems are also employed in demanding environments such as automotive electronics, where they may be used to connect power modules, requiring designs that can handle higher current loads, typically ranging from 5 to 50 amps, and resist vibration and temperature extremes from -40°C to +125°C [6].
CPU Sockets
In computer hardware, the CPU socket is a specialized and critical type of socket mounted directly onto a motherboard, providing both electrical interface and mechanical support for a central processing unit (CPU). Its design is paramount for system performance, upgradeability, and thermal management. Two dominant architectures for CPU sockets are the Pin Grid Array (PGA) and the Land Grid Array (LGA), with their fundamental difference lying in the location of the conductive pins [6]. In a PGA socket, the socket itself contains an array of pinholes, and the CPU package has a corresponding array of pins on its underside that insert into these holes. The mechanical retention and electrical contact are often secured by a zero insertion force (ZIF) lever mechanism, which reduces the risk of pin damage during installation. Conversely, in the LGA design, the pins are located on the socket, and the CPU package has an array of flat conductive pads, or "lands." The CPU is clamped into place, and the socket pins, which are often spring-loaded, make contact with these lands. The LGA design generally allows for a higher pin density, which is advantageous for modern CPUs that may require over 1,700 contacts to support multiple memory channels, PCIe lanes, and power delivery networks. The choice between PGA and LGA impacts not only the physical interface but also the thermal solution design and the handling procedures for the processor.
IC Sockets for Inspection and Testing
Within semiconductor manufacturing and testing, IC sockets serve as highly specialized jigs or interface tools. These components, also known as "IC sockets for inspection" or "semiconductor test sockets," are engineered to temporarily connect an integrated circuit (IC) package to automated test equipment (ATE) or burn-in boards [6]. Their primary function is to enable comprehensive electrical testing of semiconductor devices without the need for permanent soldering, which would be impractical and destructive during production. An IC test socket must provide a reliable electrical path from the fine-pitch leads or balls of the device—such as those in a Quad Flat Package (QFP) or Ball Grid Array (BGA)—to the larger, more robust contacts of the test board. Key design challenges include minimizing signal degradation at high frequencies (often up to several GHz), ensuring uniform contact pressure across all terminals, and withstanding tens of thousands of insertion cycles. The socket's contactors, which make the physical connection to the device, can utilize various technologies like spring-loaded pogo pins, conductive elastomers, or MEMS-based structures, each selected based on the pitch (which can be as small as 0.3mm), required bandwidth, and current-carrying capacity. By using these sockets, manufacturers can perform functional tests, speed binning, and reliability screenings efficiently, ensuring device quality before shipment.
Application in Software and Networking
The concept of a socket extends metaphorically and functionally into computer networking through software constructs. In this context, a network socket is an endpoint for sending and receiving data across a computer network, defined by a combination of an IP address and a port number. This abstraction is fundamental to inter-process communication, both locally and over the internet. Building on this foundational software concept, libraries and frameworks have been developed to simplify the implementation of real-time, bidirectional communication. For instance, Socket.IO is a JavaScript library engineered specifically to facilitate low-latency, event-based communication between web clients and servers [7]. It abstracts the complexities of various transport mechanisms, such as WebSocket, HTTP long-polling, and others, providing a unified API that allows applications to push data from server to client in real-time. This enables features like live chat, collaborative editing, and real-time notifications in web applications [7]. The library operates by establishing a persistent connection channel, over which discrete "events" with associated data payloads can be emitted and listened for, creating a dynamic and interactive user experience that mirrors the instantaneous connectivity its hardware namesake provides.
History
The history of electrical sockets is intrinsically linked to the development of standardized power distribution and the evolution of electronic components, evolving from simple power interfaces to sophisticated, specialized connectors for semiconductors and computing.
Early Standardization and Power Distribution
The concept of the socket as a removable interface for electrical connections emerged alongside the commercialization of electricity in the late 19th and early 20th centuries. Early systems were proprietary and lacked standardization, creating safety hazards and compatibility issues. A significant milestone in standardization was the establishment of the International Electrotechnical Commission (IEC), which developed specifications for plugs and sockets to ensure safety and interoperability across regions and applications. For industrial and high-power environments, the IEC 60309 standard defined robust connectors rated for currents beyond typical domestic needs. These included types such as 16A for workshops, marinas, and farms, and higher-capacity 32A, 63A, and 125A versions for clear industrial use, establishing a framework for safe, high-current disconnection [8]. This period established the socket's fundamental role as a safe, separable interface in electrical systems.
The Rise of Board-Level and IC Sockets
The mid-20th century, marked by the invention of the transistor and the integrated circuit (IC), necessitated new socket paradigms for electronics manufacturing and testing. The practice of soldering components directly to printed circuit boards (PCBs) was permanent and unsuitable for testing or replacing expensive semiconductors. This led to the development of IC sockets, which allowed chips to be inserted and removed without soldering. Initially simple in design, these sockets evolved into critical jigs, or fixing tools, for the semiconductor back-end process. Specifically designed for inspection, they became known as "IC sockets for inspection" or "sockets for semiconductor inspection," connecting IC packages to automated test equipment (ATE). Their use enabled comprehensive electrical validation of devices prior to permanent installation, a non-destructive alternative to soldering. As semiconductor packages diversified, socket designs proliferated to accommodate various form factors like Dual In-line Packages (DIPs) and later, surface-mount types.
Specialization for Testing and Burn-in
The increasing complexity and reliability demands of semiconductors drove further specialization in socket technology. A critical development was the creation of sockets for burn-in testing, a rigorous temperature-voltage stress screening performed in the final manufacturing stage. In this process, multiple ICs are loaded into specialized burn-in sockets mounted on test boards and subjected to extreme thermal loads, typically between 125°C and 180°C, under voltage for several hours to precipitate and identify early-life failures. Designing sockets for this harsh environment required materials and contact designs capable of maintaining reliable electrical connections under severe thermal cycling. Furthermore, the advent of Ball Grid Array (BGA) packages presented a formidable challenge. The solder balls on BGAs, often composed of soft alloys like 63Sn/37Pb, are prone to deformation under thermal and mechanical stress. Developing reliable BGA sockets required precise engineering to make consistent contact with these compliant spheres without damaging them, a task complicated by the need for high-density interconnections and the effects of temperature cycling in end-use applications.
Evolution in Mechanical Design and CPU Interfaces
Parallel to semiconductor testing, socket technology advanced in board-to-board interconnection and central processing unit (CPU) interfaces. For general board-level connections, socket connectors (used with pin headers) evolved to offer greater design flexibility and reliability. Modern versions support both top- and bottom-side board mating, aiding in complex PCB layouts. They incorporate advanced mechanical features such as Floating structures and Z-Move structures, which compensate for misalignment and ensure consistent contact pressure, thereby improving contact reliability. The mating pin headers for these sockets have expanded into some of the industry's most comprehensive product lineups. A major bifurcation occurred in CPU socket architecture with the widespread adoption of two primary types: the Pin Grid Array (PGA) and the Land Grid Array (LGA). The fundamental difference lies in the location of the electrical contacts:
- In PGA sockets, the pins are on the processor package, which inserts into a socket of pinholes on the motherboard. - In LGA sockets, the pins are on the motherboard socket, and the processor package has flat contact pads (lands) that sit atop these pins. This shift was driven by demands for higher pin counts, better signal integrity, and improved mechanical durability. The LGA design, by placing the fragile pins on the more easily replaceable motherboard socket, reduced the risk of damaging the expensive CPU during handling.
Recent Developments and Platform Transitions
The 21st century has seen sockets become key enablers of generational technological transitions in computing. Each new socket type often accompanies shifts in memory standards, peripheral interfaces, and power delivery. A prominent example is AMD's transition from the PGA-based AM4 socket to the LGA-based AM5 socket. This change represented a significant platform generational shift for AMD, facilitating the introduction of new memory technology, specifically dual-channel DDR5 memory [9]. While initial AM5 processors maintained support for PCI Express 4.0, the socket change was a foundational update that could accommodate future interface advances, contrasting with contemporary Intel platforms which targeted PCIe 5.0 compatibility [9]. The AM5 socket itself is an LGA type featuring 1718 pins, highlighting the continued trend toward higher-density CPU interconnections [9]. From rudimentary power connectors to highly engineered interfaces for billion-transistor processors, the history of the socket reflects the broader trajectory of electrical and electronic engineering. Its evolution continues to be shaped by the relentless demands for higher performance, increased reliability, and greater testing fidelity across the entire spectrum of electronic devices.
Description
A socket, in the context of electrical and electronic engineering, is a specialized electromechanical interface designed to provide a temporary, separable connection between two components or systems. Unlike permanent connections like solder joints, sockets facilitate repeated mating and unmating cycles, enabling testing, modularity, and component replacement. The fundamental class for interacting with a server in a networked context is also represented by a Socket [15]. The design and implementation of sockets must address core challenges in signal integrity, mechanical durability, and thermal management, with specific architectures evolving to meet the demands of different applications, from high-speed computing to semiconductor manufacturing.
Socket Connectors and Pin Headers
IRISO's "Socket Connectors" serve as a general term for connectors used in combination with pin headers (plugs) for a wide range of device-to-device and internal board connections [Source Materials]. Beyond this primary use with plugs, they are also employed for power modules in automotive electrical systems [Source Materials]. These connectors are engineered to support both top and bottom connection orientations, which significantly improves flexibility in printed circuit board (PCB) layout design [Source Materials]. To enhance performance, they are often equipped with a Floating structure and a Z-Move structure function, both engineered to improve contact reliability by compensating for misalignment and ensuring consistent mating pressure [Source Materials]. The mating partner pin headers for these systems are available within one of the industry's most comprehensive product lineups [Source Materials].
CPU Socket Architectures: PGA and LGA
Building on the concept of the major bifurcation in CPU socket architecture mentioned previously, the two dominant types are the Pin Grid Array (PGA) and the Land Grid Array (LGA). The principal difference between PGA and LGA lies in their interconnection methodology [Source Materials]. In a PGA socket, the pins are located on the underside of the central processing unit (CPU) package, which are then inserted into a grid of pinholes on the motherboard socket. Conversely, in an LGA design, the pins are situated on the socket itself, and the CPU package features an array of flat conductive contact pads (lands) that mate with these pins. This architectural shift places the more fragile pins on the typically more robust and replaceable motherboard socket, rather than on the CPU itself.
IC Sockets for Semiconductor Inspection and Testing
IC sockets are specialized jigs, or fixing tools, used for integrated circuit (IC) inspection during the back-end semiconductor manufacturing process [Source Materials]. They are also commonly referred to as "IC sockets for inspection" or "sockets for semiconductor inspection" [Source Materials]. Their primary function is to connect ICs, which are housed in semiconductor packages, to automated test equipment (ATE) [Source Materials]. This setup allows for comprehensive electrical and functional testing of ICs without requiring permanent soldering to a test board, a process that would be both impractical and destructive during high-volume production [Source Materials]. The performance of these sockets is critical, as they must maintain signal integrity at high frequencies and provide reliable electrical contact through thousands of test cycles.
Burn-in Test Sockets
The burn-in test is a critical reliability screening process involving temperature and voltage stress, performed in the final stages of semiconductor manufacturing [Source Materials]. During this test, multiple ICs are simultaneously placed into specialized burn-in sockets mounted on a test board [Source Materials]. The entire assembly is then subjected to an elevated thermal and electrical load, typically within a range of 125°C to 180°C, for a duration of several hours [Source Materials]. This accelerated aging process is designed to precipitate and identify latent or initial defects in the semiconductor devices, ensuring that only robust components proceed to customers [Source Materials]. Burn-in sockets must therefore be engineered to withstand extreme and prolonged thermal cycling while maintaining stable electrical contact.
Challenges in BGA and Advanced Package Socket Design
Developing sockets for modern semiconductor packages, particularly Ball Grid Array (BGA) and other area-array packages, presents significant engineering challenges [Source Materials]. A primary difficulty stems from the material properties of the solder balls on the devices, which are typically composed of "soft" alloys [Source Materials]. For instance, most BGA solder balls are made from a eutectic tin-lead alloy such as Sn63Pb37, which has a melting point of 183°C [Source Materials]. These soft solder balls can deform plastically over time, especially when the application undergoes temperature cycling, leading to potential contact instability and planarity issues within the socket interface [Source Materials]. Socket designers must create contact mechanisms that accommodate this deformation, apply uniform pressure across hundreds or thousands of contacts, and prevent damage to the solder balls during insertion and extraction. This requires sophisticated spring contact designs, often using beryllium copper or other high-performance alloys, with precise geometries to ensure reliable, low-resistance connections without compromising the integrity of the device under test. The structure of implementing such systems can have several downsides if not carefully modeled [13], and serious issues can arise with using Socket in certain development contexts [17].
Significance
The significance of sockets extends far beyond their basic role as electromechanical interfaces, fundamentally enabling modern electronics manufacturing, system integration, and technological advancement. Their design and application directly influence manufacturing yield, system reliability, architectural evolution, and the feasibility of next-generation packaging technologies.
Enabling Advanced Manufacturing and Quality Assurance
Sockets are indispensable in semiconductor manufacturing, particularly in the back-end process where integrated circuits (ICs) undergo rigorous electrical testing. This allows for comprehensive performance validation before devices are committed to permanent assembly. A critical application is the burn-in test, a temperature-voltage stress test performed in the final manufacturing stage [3]. During this process, multiple ICs are placed in specialized burn-in sockets on a test board and subjected to extreme thermal and electrical loads—typically between 125°C and 180°C for several hours—to screen for latent infant mortality failures and improve long-term field reliability [3]. This screening process, made practical only by the use of sockets, significantly enhances the quality and durability of semiconductor components reaching the market. The technical challenges in socket design for modern packages are substantial. Building on the fact that a primary difficulty stems from the material properties of the solder balls on the devices, which are typically composed of "soft" alloys [Source Materials], these materials can deform plastically over time, especially under thermal cycling conditions [4]. For instance, common Ball Grid Array (BGA) solder balls made from 63/37 tin-lead (SnPb) alloy are particularly susceptible to deformation. Even harder alloys like 90/10 lead-tin (PbSn) can deform sufficiently to cause intermittent electrical connections with poorly designed socket interfaces [4]. This necessitates sophisticated socket contact designs that maintain reliable electrical connection despite ball deformation, creep, and thermal expansion mismatches, directly impacting test accuracy and production yield.
Facilitating System Integration and Architectural Evolution
Sockets provide critical flexibility in electronic system design and assembly. Connector-type sockets, such as the 18021S series pin header sockets with a 2.54mm pitch and 0.64mm square posts, incorporate floating structures (Floating Mating parts) that improve contact reliability by compensating for misalignment [Source Materials]. The adoption of a bottom mating method in such designs is particularly suited for board-stacking applications, allowing multiple printed circuit boards (PCBs) to be interconnected vertically in a compact form factor [Source Materials]. By replacing manual soldering for board-to-board connections with these connectors, manufacturers avoid the reliability issues associated with delicate soldering processes and enable modular, serviceable designs [Source Materials]. This is especially valuable in automotive electronics, where sockets are used for power modules, allowing for easier replacement and repair [Source Materials]. In the realm of central processing unit (CPU) integration, the architectural choice of socket type has profound implications for system performance, thermal management, and platform longevity. This divergence is not merely mechanical but correlates strongly with application domains. PGA sockets, where pins are located on the processor package, are generally more suitable for cost-sensitive, lower-power applications such as low-end consumer electronics and embedded systems [Source Materials]. In contrast, LGA sockets, where the pins are situated within the socket on the motherboard—a design that offers better protection for the delicate contacts—have become the standard for high-performance computing [9]. LGA is the preferred interface for high-frequency servers and high-density graphics processing unit (GPU) acceleration cards, where it supports superior signal integrity, higher pin counts, and more robust power delivery [Source Materials].
Unlocking Next-Generation Packaging and Interconnect Technologies
The significance of socket technology is perhaps most evident in its role as an enabler for advanced semiconductor packaging. Different socket architectures offer varying levels of support for cutting-edge 3D packaging and optical interconnection schemes. PGA sockets provide limited support for 3D integration, typically constrained to 2D stacking approaches, and are challenged by through-silicon via (TSV) alignment errors exceeding 10 micrometers [Source Materials]. Furthermore, PGA designs are generally unable to integrate silicon photonic light engines necessary for co-packaged optics (CPO) [Source Materials]. LGA sockets, however, are architected to support more advanced integration. They are capable of supporting high-bandwidth memory (HBM) standards like HBM3, which features a 1024-bit bus with a tight 40-micrometer pitch [Source Materials]. This makes LGA essential for memory-intensive applications like artificial intelligence and high-performance computing. Moreover, the LGA form factor is conducive to realizing CPO, where optical input/output (I/O) engines are integrated within the same package as the electronic processor, dramatically reducing power consumption and increasing data bandwidth for chip-to-chip communication [Source Materials]. The transition to LGA, as seen with AMD's move from PGA-based AM4 to LGA-based AM5 sockets with 1718 pins, is often a platform generational shift that facilitates the adoption of new supporting technologies like DDR5 memory and PCIe 4.0/5.0 interfaces [9].
Supporting Development and Prototyping
Beyond mass production, sockets are vital in research, development, and prototyping phases. They allow engineers to rapidly interchange components without soldering, enabling iterative testing and validation of different semiconductor devices on a single board layout. This accelerates development cycles and reduces costs associated with fabricating new PCBs for each design iteration. The client-server architecture of software sockets, as implemented in libraries like Socket.IO for Node.js, similarly enables rapid prototyping and development of real-time web applications by abstracting complex network communication protocols [9]. This facilitates the creation of interactive features in web services, from basic chat applications to complex collaborative tools [19]. In summary, the significance of sockets permeates every level of electronics, from enabling the economic mass production of reliable semiconductors through test and burn-in processes, to providing the modular interconnect foundation for system assembly, to defining the physical interface that dictates the limits of processor performance and advanced packaging. Their evolution, particularly the shift towards LGA in high-performance computing, is inextricably linked to progress in data bandwidth, power efficiency, and 3D integration, making them a critical, though often overlooked, cornerstone of modern digital technology.
Applications and Uses
Sockets serve as critical electromechanical interfaces across diverse technological domains, enabling modular, reliable, and high-performance connections. Their applications range from facilitating board-to-board stacking in consumer electronics to supporting advanced 3D packaging and high-speed signal integrity in computing infrastructure. The specific design parameters of a socket—including pitch, mating structure, material composition, and mounting method—are meticulously engineered to meet the distinct demands of each use case.
Board-to-Board and Module Interconnections
A primary application for sockets is in creating separable connections between printed circuit boards (PCBs) or between a PCB and a functional module. This eliminates the need for permanent, delicate manual soldering, thereby improving manufacturing yield, enabling field servicing, and allowing for modular design architectures [1]. Specific series are optimized for particular interconnection challenges. For instance, the 18021S SERIES utilizes a pin header socket with a 2.54mm pitch and 0.64mm square posts, incorporating a floating structure (Floating Mating part) that improves contact reliability by compensating for misalignment [Source Materials]. Its bottom mating method is specifically designed to be most suitable for board stacking applications [Source Materials]. In display connectivity, the 9240S SERIES provides a 2.0mm pitch bottom entry socket for LCD connections, featuring a tab size of 0.5mm width by 0.3mm thickness and supporting a maximum operating temperature of 105°C [1]. It is available in 10 to 30 positions in a single row and uses surface-mount technology (SMT) for attachment to the PCB [1]. For high-density, high-speed digital signal transmission between stacked boards, connectors like the 9706S SERIES are employed [1]. This 0.5mm pitch, floating structure type connector is designed for stacking connection (ST/ST) and offers a floating range of 0.5mm in both the X and Y directions, with a 0.5mm effective mating length in the Z direction [1]. It supports high-speed transmission with a typical reference value of 1.0 Gbps, maintains differential impedance matching at 100Ω, and operates at mating heights from 8.0mm to 15.0mm [1].
Semiconductor Testing and Burn-in
Building on the function discussed above, sockets are indispensable in the semiconductor manufacturing flow for device testing and burn-in. They allow integrated circuits (ICs) in various package types to be connected to automated test equipment (ATE) without permanent soldering, which would be destructive and impractical during production [Source Materials]. Specialized sockets are designed to handle the specific challenges of modern, fine-pitch packages. Chip Scale Package (CSP) and Ball Grid Array (BGA) sockets for burn-in applications, for example, are fitted with specialized contact probes like the Aries Spring-Probe™, engineered for over 200,000 cycles of durability to withstand rigorous test and burn-in procedures [1]. These sockets accommodate a wide range of CSP-type packages with lead spacing from 1mm down to 0.5mm, including BGA, QFP, TSSOP, MLF, and QFN package types [1]. A significant technical challenge in this domain, as noted earlier, involves interfacing with devices terminated in "standard" 63/37 BGA solder balls, for which no socket company has yet successfully designed a production socket [4]. However, Aries BGA sockets and adapters are available for devices on 1.00mm to 1.27mm pitch [4].
Central Processing Unit (CPU) and High-Performance Packaging
As noted earlier, a major bifurcation occurred in CPU socket architecture with the widespread adoption of two primary types: the Pin Grid Array (PGA) and the Land Grid Array (LGA) [Source Materials]. This divergence extends beyond form factor to define their suitability for different performance tiers and advanced packaging technologies, driven by fundamental differences in materials, construction, and electrical performance. Pin Grid Array (PGA) sockets are characterized by a substrate material of FR-4 or ceramic with a coefficient of thermal expansion (CTE) of approximately 14ppm/°C, and pins formed through an electroplated hard gold process with a thickness of at least 2.5μm [1]. Their mounting accuracy requirement is ±50μm, limited primarily by pin coplanarity [1]. Electrically, PGA sockets exhibit a pin root impedance of 52Ω ±8Ω (a 15% fluctuation) and a resonant frequency of 6.8GHz with a Q factor of 32 [1]. In high-speed signal integrity tests, they typically produce an eye diagram with a height of 68mV and a width of 0.38 Unit Interval (UI), with a root mean square (RMS) jitter of 1.7ps [1]. These characteristics make PGA more suitable for low-end consumer electronics and embedded systems [Source Materials]. Furthermore, PGA's support for 3D packaging is limited to 2D stacking due to Through-Silicon Via (TSV) alignment errors exceeding 10μm, and it is unable to integrate silicon light engines for optical interconnection [Source Materials]. Land Grid Array (LGA) sockets, in contrast, use a high-density Ajinomoto Build-up Film (ABF) substrate with a lower CTE of about 10ppm/°C and employ a flexible copper post for the contact, finished with a Ni-Pd-Au plating and a typical height of 0.3mm [1]. They demand much higher mounting precision, requiring ±15μm accuracy, which typically necessitates a mounter with a vision alignment system [1]. The electrical performance of LGA is superior: it maintains a tighter pin root impedance of 49Ω ±2Ω (controlled to within 4%), a higher resonant frequency of 12.4GHz, and a higher Q factor of 58 [1]. Its eye diagram performance is correspondingly better, with an eye height of 112mV, an eye width of 0.52 UI, and an RMS jitter of only 0.9ps, comfortably exceeding common requirements of ≥60mV eye height, ≥0.35 UI eye width, and <2ps jitter [1]. These attributes make LGA the architecture of choice for high-frequency servers and high-density GPU acceleration cards [Source Materials]. Critically, LGA supports advanced 3D packaging, including High Bandwidth Memory 3 (HBM3) with a 1024-bit bus and a fine 40μm pitch, and enables Co-Packaged Optics (CPO) for optical interconnection [Source Materials]. The cost structures of the two socket types also reflect their differing applications. PGA sockets have a packaging cost factor of 8.2, a PCB manufacturing cost factor of 3.8, and a test fixture cost of approximately $1.2k [1]. LGA sockets incur a higher packaging cost factor of 11.5 (due to gold-plated contacts costing about 40% more) and a significantly higher test fixture cost of around $1.5k, as they require special pogo pin test holders; however, they benefit from a lower PCB manufacturing cost factor of 2.1 [1].