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5 Station extensions User Manual S IPLACE S-25 H M 5.5 Ceramic substrate centering Software Vers ion SR.502.xx 01/2001 US Edition 176 Obli que ligh ting m ay be switche d on instea d of t he exis ting lig hting (s ee tab…

User Manual SIPLACE S-25 HM 5 Station extensions

Software Version SR.502.xx 01/2001 US Edition 5.5 Ceramic substrate centering

175

5.5.4 Technical data

5.5.5 Optical centering with oblique lighting

5.5.5.1 General

For optical centering, the special features of the ceramic substrate must be taken into account.

The contrast depends very much on the paste used for the adjustment structure, the clear area

surrounding the adjustment structure, and the type of illumination. 5

The oblique lighting unit is located on the front part of the sub-gantry camera. 5

Fig. 5.5 - 3 Oblique lighting unit for the sub-gantry camera

Substrate format 50 mm x 50 mm to 100 mm x 180 mm

Substrate thickness 0.5 mm to 1.5 mm

Substrate model unscribed (without problems)

scribed (requires testing)

Support on the conveyor 2.5 mm

Optical centering: field of view of the PCB vision module

Type of illumination for light pastes:

Type of illumination for dark pastes and close spacing to

adjacent structures (> 1 mm)

5.7 mm x 5.7 mm

PCB vision module (standard)

Oblique lighting (option)

Fiducial criteria See PCB vision module position recog-

nition

Mechanical centering:

X/Y centering accuracy ± 0.07 mm / 4 sigma

PCB underside clearance 12 mm

Compressed air connection 5.5 bar

5 Station extensions User Manual SIPLACE S-25 HM

5.5 Ceramic substrate centering Software Version SR.502.xx 01/2001 US Edition

176

Oblique lighting may be switched on instead of the existing lighting (see table in Section 5.5.2

page 172

). 5

PLEASE NOTE

Oblique lighting can only be used on the “sub-gantry camera”. 5

5.5.5.2 Fiducial mark recommendation for ceramic substrates

The contrast between the carrier package material and the circuit-board conductor layer is gener-

ally very small with ceramic substrates. The fiducials must therefore be selected with regard to

certain criteria concerning the fiducial shape and structure. Recommended fiducial shapes and

structures are given below. 5

Fiducial shape 5

We recommend a rectangle or square with an edge length of > 1 mm, and a clearance

of > 0.5 mm. 5

Fig. 5.5 - 4 Recommended fiducial shape

PLEASE NOTE

Single crosses are also suitable, but they take up more space. 5

0.5 mm

1.0 mm

User Manual SIPLACE S-25 HM 5 Station extensions

Software Version SR.502.xx 01/2001 US Edition 5.5 Ceramic substrate centering

177

Fiducial structure 5

Recommendation 1

Fiducial structure Black resistive paste as the background, with conductive paste printed on it as

the fiducial.

Recommendation Background 0.75 mm larger than the fiducial on all sides.

Method of illumination Normal light

Advantage Good contrast, good sharpness;

Reference Circuit-board conductor layer

Assessment This combination gives the best results. Highly recommended.

Recommendation 2

Fiducial structure Fiducial made from circuit-board conductor material, e.g. 6119, and overprinted

with passivated glass 4330.

Method of illumination Oblique light

Advantage No additional steps required

Reference Circuit-board conductor layer

Assessment Fiducials are less sharp than for recommendation 1. Recommended.

Recommendation 3

Fiducial structure Fiducials made from circuit-board conductor layer against a free ceramic back-

ground.

Method of illumination Oblique or normal light (depending on the paste)

Advantage No additional steps required

Reference Circuit-board conductor layer

Note Fiducials are less sharp than for recommendation 2.

The fiducial image depends on the surrounding free surface. It may be neces-

sary to teach every circuit separately.

Assessment Recommended under certain conditions.