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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.
3.2.3 Pick and Place Cover
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.
3.2.4 Socket Insertion / Actuation Forces
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.