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User Manual SIPLAC E HF Series 7 Station extensions Software Vers ion SR.505.xx 05/2004 US Edition 7.6 Ceramic substrate centering 317 7.6.2.3 T echnical dat a 7 7.6.3 Optical centering Optical centering uses fi ducials …
7 Station extensions User Manual SIPLACE HF Series
7.6 Ceramic substrate centering Software Version SR.505.xx 05/2004 US Edition
316
7.6.2.1 Structure
Fig. 7.6 - 1 Structure of the ceramic substrate centering unit
(1) Mechanical ceramic substrate centering
(2) Centering slide
(3) Ball bearing
(4) Stop
(5) Compressed air connection
(6) Proximity switch connecting cable
(7) Lifting table
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7.6.2.2 Preventive maintenance
– Make sure to clean and grease the ball bearings in the X-axis centering unit.
– If necessary, check that the pneumatic driving mechanism is running smoothly.
– The conveyor should be maintained as described in the maintenance instructions.
User Manual SIPLACE HF Series 7 Station extensions
Software Version SR.505.xx 05/2004 US Edition 7.6 Ceramic substrate centering
317
7.6.2.3 Technical data
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7.6.3 Optical centering
Optical centering uses fiducials for centering the PCBs. You should select either the PCB vision
camera or the multicolor PCB vision camera (type 18) 21, depending on the contrast ratio of the
fiducials (see Section 7.7
).
7.6.4 Fiducial shape 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.
7.6.4.1 Fiducial shape
We recommend a rectangle or square with an edge length of > 1 mm, and a clearance of > 0.5
mm.
Substrate format 50 x 50 mm² to 102 x 178 mm²
(2" x 2" to 4" to 7")
Substrate thickness Max. 1.5 mm
Substrate model Unscribed (without problems)
Scribed (requires testing)
Clamping
X direction (direction of travel)
Y direction
Z direction
Mechanical centering
< 1.5 mm, no clamping
> 1.5 mm by lifting table with > 50 N
Support on the conveyor 2.5 mm
Optical centering with the PCB vision camera:
Type of illumination for light pastes
Type of illumination for dark pastes and close
spacing to adjacent structures (> 1 mm):
PCB vision camera (standard)
Multicolor PCB vision camera (optional)
4 illumination levels to be selected
Fiducial criteria See PCB vision module position detection
PCB underside clearance 12 mm
Compressed air connection 0.55 MPa (5.5 bar)
7 Station extensions User Manual SIPLACE HF Series
7.6 Ceramic substrate centering Software Version SR.505.xx 05/2004 US Edition
318
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Fig. 7.6 - 2 Recommended fiducial shape
7.6.4.2 Fiducial structure
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0.5 mm
1.0mm
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PLEASE NOTE
Single crosses are also suitable, but
they take up more space. 7
Recommendation 1
Fiducial structure Black resistive paste as the background.
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
background.
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
necessary to teach every circuit separately.
Assessment Recommended under certain conditions.