IPC-SM-782A-表面贴装焊盘图形设计标准.pdf.pdf - 第192页

contacts is typically 1.0 mm, 1.27 mm and 1.5 mm. The con- tacts accommodate the electrical and mechanical interface between device and host interconnecting structure (printed board). The contact material will allow conv…

1.0 INTRODUCTION

This section covers land pattern recommendations for ball

grid array (BGA) contact devices. Each subsection contains

information in accordance with the following format.

1.0 Scope

2.0 Applicable Documents

3.0 General Component Description

4.0 Component Outline

5.0 Land Pattern Dimensions

6.0 Land Pattern Analysis

The following is the table of contents for this section:

Table of Contents

Components with Ball Grid Array Contacts

Section

14.1

14.2

Family

PBGA

R-PBGA

2.0 APPLICABLE DOCUMENTS

The following documents, of the issue in effect on the current

revision date of this section, form a part of this specification to

the extent specified herein.

2.1 Electronic Industries Alliance (EIA) Automated Com-

ponent Handling (ACH) Convention

ACH:EIA-481-A Taping of Surface Mount Components for

Automated Placement.

ACH:EIA-481-3 32, 44 and 56 mm Embossed Carrier Tap-

ing of Surface Mount Components for Automated Handling.

2.2 Joint Electronic Device Engineering Council

JEDEC Publication 95 Registered and Standard Outlines for

Solid State and Related Products:

• Plastic Ball Grid Array (PBGA), MO-151 and MS-028

• Thick Matrix Tray for Handling/Shipping of Ball Grid Array

Packages, CO-028

• Thin Matrix Tray for Shipping and Handling of Ball Grid

Packages, CO-029.

2.3 Electronic Industries Association of Japan (EIAJ)

EIAJ-ED-7404 General Rules for the Preparation of Outline

Drawings of Integrated Circuits

2.4 International Electrotechnical Commission (IEC)

IEC-97 Requirements for Uniform Grid Elements

IEC-60191-2 Mechanical Standardization of Solid State

Products

2.5 Joint Industry Standards

J-STD-013 Implementation of Ball Grid Array and Other High

Density Technology

3.0 GENERAL INFORMATION

3.1 Component Description

The Grid Array device family

includes square and rectangular package configurations and

is furnished in a variety of base materials. Figure 3-1 shows

the elements of a BGA. Base material serves as a mounting

structure for attaching the die. Depending on the physical

characteristics of the material, flip-chip or wire bond technolo-

gies may be employed to route the signal from the die bond

pads to the array matrix on the base interface structure. Fig-

ure 3-2 compares the top surface attached die to the cavity

down configuration.

The interface contact or grid is arranged in a uniform column

and row format. The standard basic spacing or pitch for the

1. EIA: 2500 Wilson Blvd., Arlington, VA, 22201-3834, USA.

2. JEDEC: 2500 Wilson Blvd., Arlington, VA, 22201-3834, USA.

3. EIAJ: 8th Toyo Kaiji Building 6F, 1-5-13 Nishi-Shinbashi, Minato-ku Tokyo 105, Japan.

4. IEC: 3 rue de Verembe, PO Box 131-1211, Geneva 20, Switzerland.

5. IPC: 2215 Sanders Road, Northbrook, IL 60062

IPC-782143-1

Figure 3-1 Ball Grid Array IC package example

IPC-SM-782

Surface Mount Design

and Land Pattern Standard

Date

4/99

Section

14.0

Revision

—

Subject

Components with Ball

Grid Array Contacts

Page1of6

contacts is typically 1.0 mm, 1.27 mm and 1.5 mm. The con-

tacts accommodate the electrical and mechanical interface

between device and host interconnecting structure (printed

board). The contact material will allow conventional reflow sol-

der or other attachment processes.

3.2 Marking The Ball Array device families are generally

marked with the manufacturers name or symbol, part number,

date code and orientation mark in the corner near contact

location A1.

3.3 Carrier Package Format Devices may be furnished in

matrix tray or tape and reel packaging formats. Tape and reel

packaging is generally preferred for high volume assembly.

Plastic trays and reels must be transported and stored in

moisture proof containers. When plastic array devices are

exposed to the environment for an extended period of time,

moisture may absorb into the device. The absorbed moisture,

if excessive, may expand (when exposed to higher tempera-

tures typical of reflow solder process), causing cracking and

other physical damage.

3.4 Assembly Process Conditions The Grid Array

devices are typically attached to the host interface structure

using eutectic solder alloy however, optional methods of

attachment may include electrically conductive epoxy or poly-

mer. Array package assembly should not require specialized

equipment or processes beyond that used for vision assisted

SMT pick and place.

4.0 GENERAL CONFIGURATION ISSUES

4.1 Device Outlines

The Grid Array package outlines

detailed in this document are furnished in JEDEC Publication

95. The overall outline specification for the array device allows

a great deal of flexibility as far as lead pitch, contact matrix

pattern and construction. The JEDEC standards allow for die

attachment on either side of the interface structure (cavity up

or cavity down). Refer to J-STD-013 for further definition and

interconnect schemes for BGAs.

The example shown in Figure 4-1 illustrates two 225 I/O

devices with a common package outline but, with the variation

of contact pitch, a unique matrix format is provided.

4.2 Contact Matrix Options Contacts may be distributed

in a uniform pattern, however the matrix is always centered

about the centerline of the package (see Figure 4-2). Contact

depopulation is permitted at the discretion of the device

manufacturer. Contact patterns can usually be described in

the following methods: full even matrix, full odd matrix, perim-

eter matrix, or staggered matrix.

4.2.1 Full Matrix For a given package size, there are two

full matrix possibilities: even and odd. One of them is the larg-

est matrix that theoretically could fit on the package, given the

size and pitch of the contacts. The other matrix is smaller by

one row and column. See Figure 4-2.

4.2.2 Perimeter Matrix A perimeter matrix is achieved by

removing an array of contacts from the center of the matrix.

Center-depopulation does not affect the centerline of the

matrix. See Figure 4-3. In addition, Perimeter matrices are

usually described by the number of contact perimeters.

4.2.3 Thermally Enhanced Matrix A thermally enhanced

matrix is a perimeter matrix with contacts added back in the

center. See Figure 4-3.

4.2.4 Staggered Matrix A staggered matrix is defined by

the removal of every other contact in an interstitial pattern.

This provides an effective minimum center-to-center contact

spacing of

√

2 x pitch of the full matrix. See Figure 4-4. In

order to retain the A1 contact position, the staggered matrix

must be developed using a full odd matrix.

4.3 Selective Depopulation In addition to depopulation

methods which lead to the matrices described above, con-

tacts may be removed selectively. Selective depopulation can

be accomplished in any manner as long as the pattern matrix

is not shifted from the center of the package outline. See Fig-

ure 4-5.

4.4 Attachment Site Planning The attachment site or

land pattern geometry recommended for BGA devices is

round with the diameter adjusted to meet contact pitch and

size variation. The diameter of the land should be no larger

than the diameter of the land at the package interface and is

typically 20% smaller than the normal diameter specified for

the ball contact for pitches greater than 1.0 mm and 10%

IPC-782143-2

Figure 3-2 Examples of plastic BGA package

conﬁgurations

IPC-SM-782A

Subject

Components with Ball Grid Array Contacts

Date

4/99

Section

14.0

Revision

—

Page2of6

smaller for pitches less than 1.0 mm. Refer to the manufac-

turer specification before finalizing land pattern array and

geometry.

4.4.1 Copper Defined Land Pattern The land patterns

described are defined by the etched copper. Solder mask

clearance should be a minimum of 0.075 mm from the etched

copper land. For applications requiring a clearance that is less

than recommended, consult with the printed board supplier.

4.4.2 Solder Mask Defined Land Pattern If solder mask

defined patterns are used, then adjust land pattern diameter

accordingly. See Section 6.0.

4.5 Defining Contact Assignment Array contact identifi-

cation is assigned by the column and row location. For

example, A1 contact position is always at an outside corner

position with alpha characters arranged in a vertical (row) pat-

tern from top to bottom. Numeric characters are assigned in

a horizontal (column) axis (I, O, Q, S, X and Z are omitted). See

Figure 4-6.

The designer should note that the A1 position is at the upper

left hand corner when the device is viewed from the top. Con-

tact pattern is defined when viewed from the bottom. The land

pattern provided on the host substrate is opposite of the con-

tact pattern (with A1 contact position again at the upper left).

IPC-782144-4

Figure 4-4 Staggered

matrix

IPC-782144-5

Figure 4-5 Selective

depopulation

IPC-782144-1

Figure 4-1 Bottom view of BGA devices

IPC-782144-2

Figure 4-2 One package size, two full matrices

IPC-782144-3

Figure 4-3 Perimeter and thermally enhanced matrices

IPC-SM-782A

Subject

Components with Ball Grid Array Contacts

Date

4/99

Section

14.0

Revision

—

Page3of6