Intel LGA 771 User Manual

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LGA771 Socket

Mechanical Design Guide

November, 2006

Reference Number: 313871-002

INFORMATION IN THIS DOCUMENT IS PROVIDED IN CONNECTION WITH INTEL® PRODUCTS. NO LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS DOCUMENT. EXCEPT AS PROVIDED IN INTEL'S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, INTEL ASSUMES NO LIABILITY WHATSOEVER, AND INTEL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY, RELATING TO SALE AND/OR USE OF INTEL PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. Intel products are not intended for use in medical, life saving, or life sustaining applications.

Intel may make changes to specifications and product descriptions at any time, without notice.

Designers must not rely on the absence or characteristics of any features or instructions marked “reserved” or “undefined.” Intel reserves these for future definition and shall have no responsibility whatsoever for conflicts or incompatibilities arising from future changes to them.

The LGA 771 socket may contain design defects or errors known as errata which may cause the product to deviate from published specifications. Current characterized errata are available on request.

Contact your local Intel sales office or your distributor to obtain the latest specifications and before placing your product order.

Intel, Xeon and the Intel logo are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States and other countries.

* Other brands and names may be claimed as the property of others. Copyright © 2006, Intel Corporation.

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LGA 771 Socket Mechanical Design Guide

Contents

1

Introduction

.................................................................................................................

7

 

1.1

Document ..................................................................................Goals and Scope

7

 

 

1.1.1 ..........................................................................

LGA771 Socket Overview

7

 

 

1.1.2 .......................................................................................

Document Goals

7

 

 

1.1.3 ..................................................................................

Important Remarks

7

 

1.2

Terminology .......................................................................................................

8

 

1.3

Reference ..........................................................................................Documents

8

2

Assembled Component ...............................................................and Package Description

9

3

Mechanical Requirements ............................................................................................

11

 

3.1

Attachment ......................................................................................................

11

 

3.2

Socket ...........................................................................................Components

11

 

 

3.2.1 ..........................................................................................

Socket Body

11

 

 

3.2.2 ....................................................................

Socket Actuation Mechanism

13

 

 

3.2.3 ...............................................................................Pick and Place Cover

14

 

 

3.2.4 ...........................................................Socket Insertion / Actuation Forces

14

 

3.3

Socket ......................................................................................................Size

14

 

3.4

Socket ..................................................................................................Weight

14

 

3.5

Package/Socket ..........................................................................Stackup Height

15

 

3.6

Socket .............................................................................Loading Specifications

15

4

Electrical Requirements ...............................................................................................

19

5

Environmental .......................................................................................Requirements

21

 

5.1

Solvent ............................................................................................Resistance

23

 

5.2

Durability .........................................................................................................

23

A

Mechanical Drawings...................................................................................................

25

LGA 771 Socket Mechanical Design Guide

3

Figures

3-1

Cross-sectional view of Package / Socket stackup height1 .......................................

15

3-2

Definition of R ...................................................................................................

17

5-1

Flow Chart of Knowledge-Based Reliability Evaluation Methodology...........................

21

A-1

LGA Socket Assembly Drawing (Sheet 1 of 4) ........................................................

26

A-2

LGA Socket Assembly Drawing (Sheet 2 of 4) ........................................................

27

A-3

LGA Socket Assembly Drawing (Sheet 3 of 4) ........................................................

28

A-4

LGA Socket Assembly Drawing (Sheet 4 of 4) ........................................................

29

A-5

LGA771 Socket Motherboard Footprint (Sheet 1 of 7) .............................................

30

A-6

LGA771 Socket Motherboard Footprint (Sheet 2 of 7) .............................................

31

A-7

LGA771 Socket Motherboard Footprint (Sheet 3 of 7) .............................................

32

A-8

LGA771 Socket Motherboard Footprint (Sheet 4 of 7...............................................

33

A-9

LGA771 Socket Motherboard Footprint (Sheet 5 of 7) .............................................

34

A-10

LGA771 Socket Motherboard Footprint (Sheet 6 of 7) .............................................

35

A-11

LGA 771 Socket Motherboard Footprint (Sheet 7 of 7) ............................................

36

A-12

LGA 771 Socket Footprint (Sheet 1 of 2) ..............................................................

37

A-13

LGA 771 Socket Footprint (Sheet 2 of 2) ..............................................................

38

Tables

3-1

Intel® Xeon® 5000 Sequence Package and Socket Stackup Height ..........................

15

3-2

Socket Loading Specifications..............................................................................

16

4-1

LGA771 Socket Electrical Requirements ................................................................

19

5-1

Use Conditions Environment................................................................................

22

4

LGA 771 Socket Mechanical Design Guide

Revision History

Revision

 

Description

Date

 

 

 

 

001

Initial release of the document.

June 2006

 

 

 

 

• Updated Dual-Core 5000 & 5100 Series stackup heights

 

002

• Added Quad-Core 5300 Series stackup height

November 2006

Added Figure 3-1

 

 

 

• Removed Appendix B - Vendor Information

 

 

 

 

 

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LGA 771 Socket Mechanical Design Guide

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6

 

LGA 771 Socket Mechanical Design Guide

Introduction

1 Introduction

1.1Document Goals and Scope

1.1.1LGA771 Socket Overview

This document describes a surface mount, LGA (Land Grid Array) socket intended for the Dual-Core Intel® Xeon® Processor 5000 Sequence Family for Servers and Workstations. The socket provides I/O, power and ground contacts. The socket contains 771 contacts arrayed about a cavity in the center of the socket with solder balls for surface mounting with the motherboard. The LF-LGA771 Socket contains leadfree solder balls while the LGA771 Socket contains eutectic solder balls. This Design Guide will refer to the socket as LGA771 for simplicity, but its contents are applicable to both lead-free and eutectic solder materials unless otherwise specified. The socket contacts have 1.09 mm X 1.17 mm pitch (X by Y) in a 33x30 grid array with 15x14 grid depopulation in the center of the array and selective depopulation for keying features. A matching LGA package will be mated with the socket.

For board layout, the land pattern for the LGA771 socket is 43 mils X 46 mils (X by Y), and the pad size is 18 mils. The component dimensions are defined in metric so there is a slight round-off error when converting to mils, but it is a negligible amount, relatively speaking, when compared to the size of the ball and pad. There have been no reported manufacturing issues.

1.1.2Document Goals

The goals of this document are:

To provide LGA771 socket information necessary for motherboard design to ensure the specified performance of the platform.

To define the boundary conditions and design constraints within which the socket design must fit and perform.

1.1.3Important Remarks

All LGA771 socket characteristics mentioned in this document may change.

LGA771 socket validation reports are available from socket vendors.

LGA 771 Socket Mechanical Design Guide

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Introduction

1.2Terminology

Term

Description

 

 

LGA771 Socket

Processor in the 771-land package mates with the system board through a surface

 

mount, 771-pin, LGA (land grid array) socket.

 

 

LGA771-Land

Processors in the 771-Land package are available in a Flip-Chip Land Grid Array

LGA771 Package

package technology, consisting of a processor core mounted on a substrate with an

 

integrated heat spreader (IHS). This packaging technology employs a 1.09 mm x

 

1.17 mm pitch for the substrate lands. Refer to the processor datasheet for

 

additional information.

 

 

IHS (Integrated Heat

A component of the processor package used to enhance the thermal performance of

Spreader)

the package. Component thermal solutions interface with the processor at the IHS

 

surface.

 

 

Lead-free / Pb-free

Lead has not been intentionally added, but lead may still exist as an impurity below

 

1000 ppm.

 

 

RoHS compliant

Lead and other materials banned in RoHS Directive are either (1) below all applicable

 

substance thresholds as proposed by the EU or (2) an approved/pending exemption

 

applies. (Note: RoHS implementing details are not fully defined and may change).

 

 

1.3Reference Documents

Document

Intel Order Number

 

 

 

Dual-Core Intel® Xeon® Processor 5000

Series Datasheet

313079

 

 

 

Dual-Core Intel® Xeon® Processor 5100

Series Datasheet

313355

 

 

 

Dual-Core Intel® Xeon® Processor 5000

Series Thermal/Mechanical Design Guide

313062

 

 

 

Dual-Core Intel® Xeon® Processor 5100

Series Thermal/Mechanical Design Guide

313357

 

 

Quad-Core Intel® Xeon® Processor 5300 Series Datasheet

315569

 

 

Quad-Core Intel® Xeon® Processor 5300 Series Thermal/Mechanical Design Guide

315794

 

 

 

Note: Contact your Intel representative for the latest revisions of these documents.

§

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LGA 771 Socket Mechanical Design Guide

Assembled Component and Package Description

2Assembled Component and Package Description

The LGA771 Socket dimensions and characteristics must be compatible with that of the processor package and related assembly components. Processors using Flip-Chip Land Grid Array package technology are targeted to be used with the LGA771 socket.

The assembled component may consist of a cooling solution (heatsink, fan, clips, and retention mechanism), and processor package. The processor Thermal/Mechanical Design Guidelines (TMDG) provides information for designing components compliant with the Intel reference design.

Relevant processor 771-Land LGA package and pin-out information is given in the processor datasheet.

§

LGA 771 Socket Mechanical Design Guide

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Assembled Component and Package Description

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LGA 771 Socket Mechanical Design Guide

Mechanical Requirements

3 Mechanical Requirements

3.1Attachment

The socket will be tested against the mechanical shock and vibration requirements listed in Section 5 under the expected use conditions with a heatsink and retention mechanism attached under the loading conditions outlined in Section 3.6, and the processor datasheet. The socket will only be attached by the 771 contact solder balls to the motherboard. There are no additional external methods (i.e. screw, extra solder, adhesive, etc.) to attach the socket.

Note: Heatsink Static Compressive Loading

Heatsink static compressive loading is traditionally used for:

Mechanical performance in mechanical shock and vibration.

Thermal interface material (TIM) performance

Required preload depends on selected TIM

In addition to mechanical performance in shock and vibration and TIM performance, LGA771 socket requires a minimum heatsink static compressive load to protect against fatigue failure of socket solder joints.

Solder ball tensile stress is created by inserting a processor into the socket and actuating the LGA771 socket load plate. In addition, solder joint shear stress is caused by coefficient of thermal expansion (CTE) mismatch induced shear loading. The solder joint compressive axial force induced by the heatsink static compressive load helps to reduce the combined joint tensile and shear stress.

Overall, the heatsink required static compressive load is the minimum static compressive load needed to meet all of the above requirements: Mechanical shock and vibration, TIM performance, and LGA771 socket protection against fatigue failure.

Refer to Section 3.6 for detailed information for heatsink static compressive load for the LGA771 socket to ensure socket solder joint protection against fatigue in temperature cycling.

3.2Socket Components

The socket is made of four main components: socket body, load plate, load lever, and socket body stiffener. Refer to Appendix A for detailed drawings.

The socket will be delivered as a single integral assembly.

3.2.1Socket Body

3.2.1.1Housing

The housing material will be a thermoplastic or equivalent, UL 94 V-0 flame rating, temperature rating and design capable of maintaining structural integrity following a temperature of 260°C for 40 seconds which is typical of a reflow/rework profile for solder material used on the socket. The material must have a thermal coefficient of expansion in the XY plane capable of passing reliability tests rated for an expected high

LGA 771 Socket Mechanical Design Guide

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Mechanical Requirements

operating temperature, while mounted on an FR4-type motherboard material. The creep properties of the material must be such that the mechanical integrity of the socket is maintained for the use condition outlined in Section 5.

The color of the socket housing will be dark as compared to the solder balls to provide the contrast needed for surface-mount (SMT) equipment pick and place vision systems. Components of the socket may be different colors as long as they meet the above requirement.

3.2.1.2Package Installation / Removal Access

Access will be provided to facilitate the manual insertion and removal of the package.

To assist in package alignment and proper orientation during package installation into the socket:

The package substrate has keying notches along two opposing edges of the package and offset from the package centerline (refer to the processor datasheet for further details).

The socket utilizes one feature designed to mate with the keying notch along the inside wall of the package seating cavity (refer to Appendix A).

3.2.1.3Socket Standoffs

Standoffs will be provided on the bottom of the socket base in order to ensure the minimum socket height after solder reflow. The standoff locations and surface area located as specified in Appendix A. A minimum gap between the solder ball seating plane and the standoff prior to reflow is required to prevent solder ball to motherboard land open joints.

3.2.1.4Markings

All markings withstand a temperature of 260°C for 40 seconds, which is typical of a reflow/rework profile for solder material used on the socket, as well as any environmental test procedure outlined in Section 5 without degrading.

3.2.1.4.1Name

LGA771 (Font type is Helvetica Bold – minimum 6 point (or 2.125 mm)).

This mark shall be stamped or Laser Marked into the sidewall of the stiffener plate on the actuation lever side when eutectic solder is used.

LF-LGA771 (Font type is Helvetica Bold – minimum 6 point (or 2.125 mm)).

This mark shall be stamped or Laser Marked into the sidewall of the stiffener plate on the actuation lever side when lead-free solder is used.

Manufacturer’s insignia (Font size is at supplier’s discretion).

This mark will be molded or Laser Marked into the socket housing.

Both socket name and manufacturer’s insignia will be visible when first seated on the motherboard.

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