CAD and BOM Formats
The placement robots used at Logas require intermediate programming.
This programming involves the conversion of x-y data provided by the client (as
generated by their CAD software) to a format to be used by the robots’ database
to execute placement. The process can take days depending on the density of the
PCB (parts per board). Consequently, the data supplied will determine the level
of programming required. The two scenarios described below amplify the programming
nightmare experienced due to poor CAD data formatting.
a.
Inconsistent Data: This is when a part
occur in two or more locations on a PCB but are being assigned different package
names:
REF.ID
P/N
PACKAGE
X
Y
R
R1
RM1000
R0603
54
44
180
R2
RM1000
0603
65
77
90
The
data ftip software will not complete the conversion. This is a control mechanism
to minimize placement errors which may be in the form of placing a part in the location
meant for another type of part but with similar package size.
The package name for part number 2 will be corrected to read R0603 for the program to
run.
This will also create additional programming requirements. The database
conversion program assumes that part numbers are unique. Hence, if a part occurs
more than once on a PCB, each occurrence would be mapped to the unique part number.
Therefore, if a part value is used to denote part number in the CAD program, the
software will map package type to part value. It is common knowledge that two or
more parts can have the same value, rating and tolerance but different package sizes.
Programming problems of the kinds described above introduce defects; since manual adjustments
becomes necessary to prepare the CAD data in a format that the conversion software
will accept. Consequently, the practice of adjusting CAD data impacts data integrity.
Logas quality system does not allow for CAD data adjustment of
this nature.
Clients are advised to assign their own unique part identifiers and to incorporate these
into their CAD system. Common format could be in the form of the table below:
Ref.ID. Part
No. Package x y r
Side
R1
RM1000
R0603
76 88 180 TOP
R2
RM1000
R0603
89 73 90
TOP
R3
RM1200
R0805
43 33 0
BOTTOM
C3
CA1000
C0603
80 44 0
TOP
C4
CA1302
C1206
26
10 90 BOTTOM
…
…
…
… … … …
For the bill of materials (BOM), it is recommended that the same format
be adopted as the one described above (use of unique part identifiers and differentiating
package types).
Part No. |
QTY |
Circuit Ref/RefID |
Description |
Mfg. P/N |
RM1000 |
2 |
R1, R2 |
Res, 120k, 10V, 0603 |
ERO10276RC |
RM1200 |
1 |
R3 |
Res, 10k, 20V, 0805 |
ERO00019RC |
CA1000 |
3 |
C3,C6,C10 |
Cap, 1uF, 0.25W,0603 |
ECP17263CP |
CA1302 |
4 |
C9,C12,C11,C14 |
Cap, 45uF, 0.12W,1206 |
ECP11001CP |
Recommended Bom format...
|