SIPLACE Vision Customer_en - 第129页
SIPLACE Vision - T eaching Fiducials PCB Position Recognition Fiducials in the PCB Layout What are Fiducials? S tudent Guide SIPLACE Vision (Customer) Edition 12/2008 EN SIPLACE Vision - T eaching Fiducials 129 6.1.1 PCB…
SIPLACE Vision - Teaching Fiducials
What are Fiducials?
Student Guide SIPLACE Vision (Customer)
SIPLACE Vision - Teaching Fiducials Edition 12/2008 EN
128
The fiducial can only be trained, tested or used for placement, if the fiducial coordinates for the PCB are
known and have been sent to the machine.
Fiducials are approached in the following order during testing or placement:
PCB position recognition fiducials
Inkspot fiducials (global inkspot first; - also in bad case – and then the local inkspot fiducials of the
panels).
Component placement position fiducials.
If fiducials are trained, the operator determines the order of these fiducials through his selection. If the
position tolerance values are not set to maximum tolerance for all fiducials, the size of the tolerance field
will determine the order of PCB recognition fiducials. The fiducial with the greatest tolerance will be
approached first and that with the smallest tolerance will be approached last.
The SIPLACE Pro coordinate data includes:
The PCB/panel assignment
The fiducial position coordinates (X, Y)
The position tolerance data and
Use on the respective PCB (position
recognition fiducial; inkspot fiducial; placement
position fiducial).
It may also make sense to program more
fiducial coordinates and numbers and to
temporarily omit them when not needed.
SIPLACE Vision - Teaching Fiducials
PCB Position Recognition Fiducials in the PCB Layout What are Fiducials?
Student Guide SIPLACE Vision (Customer)
Edition 12/2008 EN SIPLACE Vision - Teaching Fiducials
129
6.1.1 PCB Position Recognition Fiducials in the PCB Layout
The number of fiducials in the PCB layout results in the following options for placement quality
optimization:
1 fiducial The X/Y position of the PCB can be measured in the conveyor - placement area of the
machine. ATTENTION: Is not sufficient for SIPLACE machines and is blocked by the SW.
2 fiducials The X/Y position of the PCB and the PCB angular position can be determined in the
conveyor - placement area of the machine. This is the minimum required for SIPLACE machines!
3 fiducials If the fiducials are arranged appropriately on the PCB layout (L shaped), a PCB offset can
be recognized and corrected.
More than 3 fiducials can be programmed, although only the first 3 will be used. When using the
long board option, up to 6 programmed fiducials are used, depending on the relevant placement
stop. There is also a possibility that coordinates are programmed for multiple coordinates but are
then intentionally deactivated.
The arrangement of fiducials can be more or less favorable for the placement process.
6-1: Favorable arrangement of PCB position recognition fiducials
The following accuracy parameters apply for
extreme accuracy requirements:
If a position error occurs during fiducial
recognition, a placement error in the vicinity of the
central position (the intersection of the medians) of
the triangles would be approx. 0.6 x fiducial
measurement error.
In the area of the ellipse, the error would be as
large as the measurement error during position
recognition.
In the area of the double ellipse, the placement
error would also be doubled.These geometric
relations are independent of the Vision system and
should encourage you when selecting the fiducials
to take at least half the PCB dimensions as the
distance between fiducials.
6-2: Non-recommendable arrangement of PCB position recognition fiducials
If the distance of the fiducials programmed for
PCB position recognition was as near as in items
B and C, the right PCB edge would show a PCB
position recognition measurement error as a
multiplied (in this case about 20 fold) placement
position error.
A PCB production offset along the length would
not be recognized here.
This discussion about the two fiducial position
layouts should encourage you to select the
fiducials wisely.
If the programmed distances for the position
recognition fiducials on the whole PCB are not
observed, some SW versions will issue a
plausibility error.
SIPLACE Vision - Teaching Fiducials
What are Fiducials? PCB Position Recognition Fiducials in the PCB Layout
Student Guide SIPLACE Vision (Customer)
SIPLACE Vision - Teaching Fiducials Edition 12/2008 EN
130
Fiducial arrangement layout
When arranging fiducials for PCBs with multiple consolidated panels, this arrangement of fiducials can
either be recorded once for the entire PCB or each of the individual switching circuits can be assigned
its respective fiducials and recorded.
You can not program and use the PCB position recognition both for the entire board AND for a single
panel at the same time. If this is programmed, the PCB position recognition will give the panel priority
and the fiducials for position recognition of the entire board will not be approached and centered.
The following description explains the special case of the "long board" option.
Layout for fiducial arrangement if the "long board" option is used
In the long board option, the PCB is stopped twice in the placement area of the machine: once at the
laser light barrier – PCB placement area of the 1st stop and then at the mechanical stopper of the long
board option - PCB placement area of the 2nd stop. 3 fiducials for PCB position recognition can be
distributed throughout the length of the relevant placement stop area.
Fiducials in the overlap area can be used for position recognition of both the 1st and the 2nd area. This
means that 4 to 6 fiducials in total can be programmed for position recognition of a "long board".
As can be seen in the diagram labeled "Non-recommendable arrangement of PCB position recognition
fiducials" (see above), it is not advisable to concentrate the PCB position recognition fiducials for both
placement areas just in the overlap area.
Fiducials in the panels if the "long board" option is used
If all fiducials and placement positions are in the placement area of the respective stop, you can also use
the position recognition fiducials for the panels (see the 3 crosshairs in each panel).
If one placement position is located in the placement area of the other stop, this type of PCB position
recognition will not function in the machine with the long board option.
After performing PCB position recognition, the fiducials for other optical PCB recognition runs will be
approached. From the introduction of SIPLACE Vision, position recognition is ALWAYS performed
BEFORE inkspot recognition.
6-3: Possible distribution of PCB position recognition fiducials for long board
option
The PCB stopped at the laser light barrier can be
placed in the area marked as '1'.
2 fiducials from the front row of 4 fiducials and one
fiducial in the overlap area (2nd row of four) form
the 3 fiducials for the placement area of the 1st
stop.
2 fiducials in overlap area ’3’ and one in the row of
2 fiducials at the end of the PCB form the fiducials
for the placement area of the 2nd stop (arrow ’2’)
at the mechanical stopper for the long board
option.