80S-2080F480F4-680F5 User’s Manual.pdf - 第247页
5 Vision Functions SIPLACE 80S-20/F4/F4-6/F5 User’s Manual 5.2 PCB Vision S ystem Edition 03/98 from Software Version SR.404.xx 5 - 26 Line engine er – Correc tion with two fiduci als x-position y-posi tion PCB ske w – C…
SIPLACE 80S-20/F4/F4-6/F5 User’s Manual 5 Vision Functions
Edition 03/98 from Software Version SR.404.xx 5.2 PCB Vision System
Line engineer 5 - 25
– Thickness (d)
You should ensure, particularly with tin fiducials, that a warpage of more than 1/10 of the structure width is
not exceeded. If this degree of warpage is exceeded then under certain circumstances the fiducial may not
be evenly illuminated. This would lead to variations in reflection characteristics and unwanted reflections.
Recognition of the fiducials will then no longer be assured.
Recommended fiducial dimensions
Evaluation of the fiducial shapes
With tinned structures and higher dimensional stability (a low degree of etching variation) full circles or full
squares may be regarded as very satisfactory fiducial shapes (the ratio of fiducial thickness to presoldering
thickness will be large!). If dimensional stability falls, the full circle should be preferred to the square.
As far as the fiducial shapes of simple and double cross are concerned, bright copper is advantageous as
long as oxidation has not advanced too far.
l Surface of the fiducials
Make sure that the surface of the fiducial is as level as possible and with little oxidation. Avoid wetting the
fiducial with solder-stop lacquer as this could result in lowering the contrast with the background or pro-
duce unwanted reflections. Similar effects occur with tinned fiducials as well.
l Contrast of the fiducials
To ensure that fiducial recognition is of a high quality select a high brightness contrast between the fiducial
and the base material; in other words, bright fiducials on a dark base material and vice versa. For example,
on a copper or tin background apply dark fiducials. In the case of ceramic substrates with a bright surface
and unsatisfactory reflective properties it is often helpful to precoat with a dark resistance material in order
to improve contrast characteristics.
l Number of fiducials
When using ceramic substrates and small boards it will usually be sufficient to apply two fiducials. How-
ever, with larger boards it is recommended that three fiducials be defined. The individual fiducials can vary
in structure. You can simplify the recognition procedure if you use the same structure for each fiducial.
Fiducial type
Simple cross Double cross
Range Ideal range Range Ideal range
Length (l) 0.9 mm (min) 2.0 mm 1.8 mm 2.75 mm
Width (b) 0.9 mm (min) 2.0 mm 1.8 mm 2.75 mm
Line thickness (s) 0.3 - 1.5 mm 0.5 mm 0.3 - 0.75 mm 0.5 mm
Line spacing (a) — — 0.5 mm (min) 0.75 mm
Thickness (d) < 1/10 of the structure width < 1/10 of the structure width
Tab. 5.2.2 Recommened fiducial dimensions
5 Vision Functions SIPLACE 80S-20/F4/F4-6/F5 User’s Manual
5.2 PCB Vision System Edition 03/98 from Software Version SR.404.xx
5 - 26 Line engineer
– Correction with two fiducials x-position
y-position
PCB skew
– Correction with three fiducials: ideally the straight lines which each pass through the centers of two
fiducial will be parallel with the x and y axes
x-position
y-position
PCB skew
Shear
Warpage of PCB in the x direction
Warpage of PCB in the y direction
NOTE
You should never position 3 fiducials so that they are located on a straight line.
Spacing between the fiducials
You may locate the fiducials at any point on the board. However, it is a good idea to space the fiducials as
far apart as possible on the two axes. The further apart the fiducials are from one another, the more accu-
rate optical position and angle recognition will be.
SIPLACE 80S-20/F4/F4-6/F5 User’s Manual 5 Vision Functions
Edition 03/98 from Software Version SR.404.xx 5.3 Component Vision System
Line engineer 5 - 27
5.3 Component Vision System
The component vision system records the precise location of a component by determining on the one hand
the displacement of the center of the component relative to the nozzle’s axis of symmetry and on the other
hand by determining the board’s skew with respect to the relative rotational position of the nozzle. It is also
possible to carry out an analysis of the state of the lead configuration in both the x and y directions.
5.3.1 Component Vision System of the SIPLACE 80S-20 Placement
Machine
5.3.1.1 Description of the System
The component vision system consists of:
l the optical system for component position recognition
Each 12x revolver placement head is equipped with its own component position recognition system in star
station 7 (see Fig. 5.1.3, Page 5 - 6).
l the vision evaluation unit
Each machine is equipped with an evaluation unit for PCB and component position recognition which is
accommodated in the control unit (see Fig. 5.1.4, Page 5 - 7 and Fig. 5.1.7, Page 5 - 10).
A CCD camera with deflection mirror, imaging lens and LED lighting system constitutes the optical component
position recognition system. The effective field of view of the CCD camera (a SONY XC75) amounts to 24 x
24 mm². For position recognition or for leads testing the component is evenly illuminated by the rows of LEDs
in the reflected light process and its sharp image formed by the lens on the CCD chip. Using digital image pro-
cessing methods, the HALE process (H
igh Accuracy Lead Extraction) the parameters are determined for
position, skew and leads condition.
The vision evaluation unit (MVS) has already been described in Section 5.2.1 since it performs the two func-
tions of PCB and component evaluation.
5.3.1.2 Technical Data
Camera type: SONY XC75
Number of pixels: 484 x 484
Field of view: 24 mm x 24 mm
Method of illumination: Reflected light process (red light), 3 LED levels
Image processing: HALE gray scale process (H
igh Accuracy Lead Extraction)
Screen: RGB monitor (VGA mode) 640 x 484 pixels
Component sizes: 0.5 mm x 0.5 mm to 18.7 mm x 18.7 mm
Range of recognizable components : TSOP, LCC, PLCC, QFP, SO series through SO28
basically all components with J and
gull-wing leads, µBGAs
Minimum lead pitch: 0.3 mm
Minimum ball diameter with µBGAs: 250 µm