SIPLACE 80 F4_EN - 第32页

31 Description P P P Pl l l la a a ac c c ce e e em m m me e e en n n nt t t t R R R Re e e eli li li lia a a ab b b bili ili ili ilit t t ty y y y Aside from correct positi oning, placement reliabilit y also means a gen…

Description

Various factors contribute to the

placement accuracy of the

SIPLACE 80 F

machine, e.g., the

stationary PCB during the place-

ment process. As no accelerations

are acting on the placed compo-

nents, their position continues un-

changed. The PCB moves in and

out at a coordinated speed which

is automatically reduced just be-

fore the nominal position is

reached.

A further guarantee for long-term

high placement accuracy is the

position recognition of the axes of

the gantry and placement head by

means of optical scanning by in-

cremental encoders. Revolving

star and segments of the revolver

head are positioned by means of

high-resolution glass incremental

panels. The X- and Y-axes are posi-

tioned with the help of the metal

scales on each gantry axis.

To determine the placement accu-

racy on SIPLACE machines, highly

precision glass components with

mounted structures are placed on

a dimensionally accurate glass

mapping plate. The results are sta-

tistically evaluated and presented

as a Gaussian standard distribu-

tion. In the case of the 12-nozzle

revolver head the placement accu-

racy is ± 90 µm at a statistical reli-

ability of 4 sigma. In other words,

of one million placed components,

60 are outside the specified toler-

ance (= 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

Technical Data Gantry

Drive DC servomotors

Position measuring system (X/Y) Linear scales

Resolution of X-/Y-axis 2.5 µm

Speed of X-axis max. 2 m/s

Speed of Y-axis max. 2.5 m/s

Accuracy

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

12-nozzle revolverhead

Angle accuracy

Placement accuracy

± 0.525° / 3 σ

± 0.70° / 4 σ

± 1.05° / 6 σ

± 67.5 µm/ 3 σ

± 90 µm/ 4 σ

± 135 µm/ 6 σ

Pick & Place-head

Angle accuracy

Placement accuracy

± 0.052° / 3 σ

± 0.07° / 4 σ

± 0.105° / 6 σ

± 37.5 µm/ 3 σ

± 50 µm/ 4 σ

±75 µm/ 6 σ

Standard Deviation - dpm

-4

-3

-2

σσ

2700 dpm

60 dpm

P Point of Inflection

Description

t t

t R

eli

lili

lia

bili

iliili

ilit

Aside from correct positioning,

placement reliability also means a

gentle handling of the compo-

nents, so that these can be sol-

dered well later. Rework is mini-

mized or eliminated as a result.

On the SIPLACE 80 F

among

others this is ensured through a

number of control functions, e.g.,

the vacuum checks and compo-

nent vision test during the revolver

head sequence.

Unsuitable components are re-

jected, placed on the repair list and

automatically processed during a

repair cycle. An offset in the posi-

tion of the PCB relative to the con-

veyor system (PCB vision) and an

offset of the X-axis, Y-axis or rota-

tion of the component relative to

the midpoint of the nozzle (com-

ponent vision) trigger an immedi-

ate correction and thus placement

accuracy.

Thanks to the motionless PCB the

components remain in the exact

position they were placed. The

stationary component table pro-

tects, for example, the compo-

nents in Bulk Cases against dam-

age such as may occur due to

vibrations which are inevitable with

other placement concepts. Op-

tional add-on products ensure fur-

ther reliability: With the aid of the

component bar code scanner, the

correct placement program is

automatically sent to the station.

-u

p p

p e

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

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

When used alone on the SIPLACE

80 F

the 12-nozzle revolver head

achieves a benchmark placement

rate of 10,000 components per

hour (cph). The Pick & Place head

places at a max. speed of 1,800

cph. These benchmark rates can

be verified on the demonstration

PCB at Siemens.

Factors such as PCB size, number

of components per board and their

layout have a certain effect on the

speed in actual practice. The

placement speed in practice can

be predicted using a calculation

program.

Machine Criteria:

Placement Reliability and Placement Speed

Placement Principle SIPLACE 80 F

Pick & Place Head

PCB Transport

Direction

Revolver Head

X/Y-Gantry

System

Fixed PCB

Fixed Component

Description

Despite the highly stable machine

frame, slight distortions of the

gentry axes cannot always be

avoided. With the aid of the map-

ping process the high placement

accuracy of the machine is pre-

served throughout its entire serv-

ice life.

With this calibrating procedure,

which can be conducted quickly

and easily, the PCB camera recog-

nizes the fiducials on a mapping

calibration plate placed in its oper-

ating area. Any distortions are re-

vealed by comparing the nominal

grid on the glass plate with the ac-

tual grid “drawn” by placement

head. These distortions are taken

into account during all further posi-

tioning of X-/Y-axes and thus com-

pensated for.

Machine Criteria:

Mapping (Option)

Technical Data

Dimensions of the mapping

test plate

520 x 460 mm (for single conveyor)

520 x 215 mm (for dual conveyor)

Number of measurement

points

13 x 11 (standard resolution)

26 x 21 (high resolution)

Ambient temperature during

calibration + 20° ± 3°C

Components of the option

Test plate (special glass)

Calculation data (disk)

Case for secure storage

Nominal Grid of Mapping Plate and Actual Grid with

Deviations Due to Gantry

Corrected

Position