IPC-CM-770D-1996 - 第121页

January 1996 IPC-CM-770 0.1 mm [0.004 inch] TYP TYP TYP ,0.025 mm [0.001 inch] ball IPC-1-00340 Figure 23-3 Thermocompression Ball Wire Bonding Parameters where the assembly actually takes place. Semiconductor now be tur…

IPC-CM-770

Januaty

1996

Bond

Force

Second Search

Ball is

Reformed

Torch

Home

Wire

Ball on End

Tip Withdrawn

Wedge Bonding

Operation

,ce

Alt. Tail

Pulling

Work Moved Toward

Position

Tip

Withdrawn

Wedge

Diffusion

Bond

Alt. Tail

Pulling

Ball

Retracted

IPC-1-00341

Figure

23-2

Mechanics

Thermocompression

Ball

Wire

Bonding

5-18

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January

1996

IPC-CM-770

0.1

[0.004

inch]

TYP

TYP TYP

,0.025

[0.001

inch]

ball

IPC-1-00340

Figure 23-3 Thermocompression Ball Wire Bonding Parameters

where the assembly actually takes place. Semiconductor now be turned to the proper angular alignment, picked-off

devices can be handled by equipment such as this, with the nest and placed onto the board. The motion is also pro-

chip dimensions ranging from

0.5

7.5

mm.

vacuum grammable to control chip placement pressure.

force is typically used to pick up the chips, thus eliminat-

ing distortions or scratches from mechanical fingers.

vacuum sensing circuit is also often used to detect if a

23.4.3 Fully-Integrated Systems

High-volume fully

device was picked up and transported correctly.

integrated systems are also being developed for multichip

applications.

typical system, Figure

23-8,

processes up to

The more-sophisticated units have a pattern-recognition

inch by

inch boards in

unit magazine-to-magazine

feature that is performed by a camera system that is fed system equipment.

fully-integrated system could be

mounted directly over the centering nest. The orientation is configured to include equipment for adhesive silk screen-

then electronically compared with stored images and the ing, pick-and-place die attachment, wireAead bonding, and

device is turned to the correct orientation. The chip can chip sealing.

5-19

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IPC-CM-770

Januaty

1996

Figure 23-4 Mechanics

Ultrasonic Wire Bonding

IPC-1-00339

Figure 23-5 Thermosonic Wedge Wire Bonding

Such a system would operate in the following manner.

First, bare boards loaded in 50-unit magazines are pre-

sented to the input feed magazine of the silkscreener,

where adhesive is deposited. Then the boards with adhesive

are automatically transferred to the pick-and-place

machine, where the chips are placed on the board over the

adhesive. The populated boards are then put back in the

magazine for further processing.

The magazines are removed from the output of the chip

attachment unit manually and put into an oven to cure the

adhesive. The boards, after curing in the magazines, are put

into the wirelead bonder's magazine feed. The chips are

then bonded to the boards and automatically put back into

IPC-I-

Figure 23-6 Typical Low-volume COB Chip Handling

System

the magazines. These magazines are manually placed into

another wire/lead bonder for inspection and repair.

The inspected magazines are then taken to the chip-sealing

unit. The boards are environmentally sealed and returned

automatically to the magazines. These sealed units are then

taken to another oven for curing of the sealing compound.

more sophistication is desired, a control console can be

added to oversee the operation of the system that consists

of a closed-circuit television monitor, a keyboard and a

tracking assembly which allows an operator to remotely

intervene in the operation of the equipment.

24.0 TAPE AUTOMATED BONDING (TAB)

One promising type of Fine Pitch Technology is Tape

Automated Bonding (TAB). TAB uses photo-imaging/

etching processes to produce conductors on a dielectric/

conductor tape "movie film" format. (See Figure

24-1).

The most visible aspect of the TAB system is the carrier

tape, which is

mm wide and stored on reels. Win-

dows are formed at specific locations in the tape and a thin

conductive layer is applied to the tape; usually 0.035mm

thick copper. A conductive pattern is then created in the

conductive layer to give the desired interconnection cir-

cuitry with "beam type" leads that extend over the win-

dows in the tape. In subsequent processing, the beams are

bonded to an integrated circuit die that is precisely located

under the windows. Sprocket holes or features on the tape

carrier permits automated tape-handling equipment to

accurately position the individual dice for the subsequent

processing operations, such as testing, bum-in, and board

mounting. Fiducials/registration marks on the tape may be

used for alignment with vision systems during bonding/

handling.

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