Specification_SIPLACE_S23HM_eng - 第23页

22 Description Various fac tors contribute to the placement precision of the SIPLAC E S-23 HM system, for ex - ample the PCB which is station ary during the placement process. Components previously placed are not affecte…

Description

The component vision module in-

tegrated into the placement head

significantly contributes to place-

ment precision and reliability. It

dependably recognizes all package

forms (= geometric dimensions of

the component) which are illumi-

nated at various angles from three

planes in the case of the 12-nozzle

revolver head. For optimal illumina-

tion of each component, the

brightness of the lighting of the

planes can be adjusted individually

in 256 increments.

Aside from the dimension of the

SMD module, the vision system

determines the number of leads

and their pitch (lateral IC lead bend)

as well as the offset of the place-

ment angle and the X-/Y-axis. Un-

suitable components are rejected

and automatically added later in a

repair cycle. Offsets in placement

angle and X-/Y-axis are corrected at

the turning station of the revolver

head or via the gantry axes. From

the positions of a number of com-

ponents in one track a relevant

offset in the pick-up position on

the X-/Y-axis is calculated. This off-

set is taken into account during

subsequent component pick-up

steps due to the self-learning prin-

ciple.

Prior to placement, the required

geometric dimensions of a com-

ponent type are entered into the

GF editor, creating a synthetic

model of the SMD chip. This task

is facilitated by the extensive on-

line information and help system.

The central SIPLACE vision sys-

tem, to which the other vision

modules are also connected, sub-

sequently analyzes the gray-scale

value of the component vision

module. Algorithms suitable for

the specific package form are used

for this purpose. Due to the com-

bination of algorithms, the vision

system also functions reliably un-

der the most difficult conditions,

e.g., in case of different reflection

behavior on the part of the leads or

interference from outside.

Vision Sensor Technology:

Algorithms to Determine the X-/Y-Position and the

Placement Angle

Algorithm Component Analysis based on

Size Driven Chip the component contour (pro-

file/gradient)

Row Driven IC Several component leads (correla-

tion method)

Corner Driven IC all component leads

(correlation method)

Lead Driven Complex IC Each component lead (High-

Accuracy-Lead-Extraction method)

Grid/Ball

BGA, µBGA,

Flip Chip

all defined balls

(gradients/ball centering)

Description

Various factors contribute to the

placement precision of the

SIPLACE S-23 HM system, for ex-

ample the PCB which is stationary

during the placement process.

Components previously placed are

not affected by any forces of ac-

celeration, therefore their position

remains stable. The PCB is moved

in and out at a coordinated speed

which is automatically reduced just

before reaching the target position.

A further guarantee of long-term

high placement precision is the

position recognition feature of the

gantry and placement axes by op-

tical scanning of increment encod-

ers. Revolving star and segments

of the revolver head are positioned

by means of high-resolution glass

incremental panels. The X- and Y-

axes are positioned with the aid of

metal scales on each gantry axis.

In order to ascertain the placement

precision on SIPLACE machines,

high-precision glass components

with applicated structures are

placed on a dimensionally accurate

glass mapping calibration board.

The results are analyzed statisti-

cally and represented as a Gaus-

sian standard distribution. In the

case of the 12-nozzle revolver

head the placement precision is

± 90 µm at a statistical reliability of

4 sigma. In other words, out of one

million placed components 60 may

be outside the specified tolerance

(- 60 dpm). If the accuracy value

± 90 µm is divided by the sigma

value 4, the result is the standard

deviation S of 1 sigma =

± 22.5 µm.

A machine capability analysis is

conducted for each machine ac-

ceptance test.

Machine Criteria:

Placement Accuracy

2700 dpm

60 dpm

Standard Deviation - dpm

P Point of Inflection

Technical Data Gantry

Drive AC servomotors

Position measuring system (X/Y) Linear scales

Resolution of X-/Y-axis

2.5 µm

Speed of X-axis max. 2.5 m/s

Speed of Y-axis max. 2.5 m/s

Accuracy

X-/Y- and D-axis offset in optical component and PCB centering

Angle accuracy ± 0.525° / 3 σ

± 0.70° / 4 σ

± 1.05° / 6 σ

Placement accuracy

± 67.5 µm/ 3 σ

± 90 µm/ 4 σ

± 135 µm/ 6 σ

-4

-3

-2

σσ

12-Nozzle Revolver Head

X-/Y- Portal System

Fixed Component Supply

Fixed PCB

Description

lac

acac

ace

men

enen

ent

t t

t R

eli

lili

lia

bili

iliili

ilit

Aside from correct positioning,

placement reliability also signifies

gentle handling of the components

so that they can also be soldered

well later. This minimizes or elimi-

nates rework.

This is guaranteed on the SIPLACE

S-23 HM, for example, by a num-

ber of check functions such as the

vacuum checks and the compo-

nent vision test during the revolver

head cycle. Unsuitable compo-

nents are rejected, placed on a re-

pair list and automatically added

during a repair cycle. An offset in

the position of the PCB relative to

the conveyor system (PCB vision

module) and an X-, Y- or rotational

offset of the component relative to

the midpoint of the nozzle (com-

ponent vision module) result in

immediate correction and thus

placement precision.

Thanks to the stationary PCB the

components remain in their exact

placement position. The stationary

component table protect, for ex-

ample, the components in Bulk

Cases from damage such as may

occur due to vibrations which are

unavoidable with other placement

concepts. Optional add-on prod-

ucts provide further reliability. The

component bar code scanner de-

pendably recognizes components

which were set up incorrectly. The

correct placement program is

automatically sent to the station by

using the PCB bar code

-u

p p

p e

err

rrrr

rro

All errors which occur between the

time the component is picked up

and the time it is placed on the

PCB are pick-up errors. They in-

clude:

No component in the tape

Component cannot be removed

from the tape.

Vacuum error

Vision error due to faulty com-

ponent

Vision error due to unrecognized

component

t t

t e

err

rrrr

rro

Errors which occur after the com-

ponent has been placed on the

PCB. They include:

Rotation error

Too many components on PCB

X/Y-offset

t t

t S

pee

eeee

eed

SIPLACE S-23 HM achieves a

maximum placement speed of

23,000 components per hour (cph).

This benchmark rate can be veri-

fied with a demonstration PCB at

Siemens.

The SIPLACE concept is based on

a horizontal axis of rotation of the

12-nozzle revolver head, the sta-

tionary component table and the

PCB which is motionless during

placement. This principle permits

a revolving start cycle time of

140 ms regardless of the compo-

nent. For this reason, the bench-

mark rate is already close to the

placement speed in actual practice.

Nevertheless, various factors exert

a certain influence, e.g. the PCB

size, the number of components

per PCB and their layout. The

SIPLACE concept also has a posi-

tive effect here, too, because, un-

like other concepts, it permits a

further optimization of positioning

and sequence.

The placement speed in actual

practice can be predicted on the

basis of a computation program.

Machine Criteria:

Placement Reliability and Placement Speed

Placement Principle SIPLACE S-23 HM