Intel LGA 771 3.3 Socket Size, 3.4 Socket Weight

Mechanical Requirements

14 LGA 771 Socket Mechanical Design Guide

The stiffener plate is made of stainless steel SUS 301. The stiffener plate provides the

interface to the load lever and the load plate and creates the primary stiffening element

to react to the load generated by the load plate.

The pick and place cover is a dual purpose removable component common to the

LGA771 socket. The cover’s primary purpose is to provide a planar surface at least

20 mm in diameter and compatible with SMT placement systems. As such, the cover

retention must be sufficient to support the socket weight during lifting, translation, and

placement. The cover material should be chosen such that it is able to withstand 260°C

for 40 seconds.

The secondary function of the Pick and Place Cover is to provide a physical barrier

against contamination and undesirable physical contact of the socket contact array

during post-SMT handling environments in board assembly environments, during

shipping, and in system assembly environments. As such, cover retention is sufficient

for the cover to remain in place through these environments. The cover should be able

to be installed and removed without the use of tools.

There should be no surfaces or features above the pick surface. The Pick and Place cap

should attach to the exterior of the Load Plate to maximize its distance from the socket

contacts and be compatible with volumetric keep-ins as defined in the processor

Thermal/Mechanical Design Guidelines. The cover should not have features that

protrude below the Load Plate inner profile and into the socket cavity. Also, there

should be no features that protrude above the pick and place surface. Further, any vent

holes added to the Pick and Place Cover to aid in air circulation during reflow should be

positioned as to not allow fluid contaminants a direct path to the contacts (i.e. no

socket contacts should be visible with the cover installed). Finally, a Pin 1 indicator,

typically a triangular cutout, on the Pick and Place Cover is highly desirable.

Any actuation must meet or exceed SEMI S8-95 Safety Guidelines for Ergonomics/

Human Factors Engineering of Semiconductor Manufacturing Equipment, example Table

R2-7 (Maximum Grip Forces).

The socket must be designed so that it requires no force to insert the package into the

socket.

The load lever actuation force must not exceed 3.9 kgf [8.6 lbf] in the vertical direction

and 1 kgf [2.3 lbf] in the lateral direction.

The pick and place cover insertion and removal force must not exceed 1 kgf [2.3 lbf].

3.3 Socket Size

Socket information needed for motherboard design is given in Appendix A.

This information should be used in conjunction with the reference motherboard keep-

out drawings provided in the processor Thermal/Mechanical Design Guidelines to

ensure compatibility with the reference thermal mechanical components.

3.4 Socket Weight

The LGA771 socket will weigh around 35 g, which includes the mechanical components.