Post on 02-Jan-2016
description
Measurements of the Printed Circuit Boards (PCB)
Simon Gonzalez (CSU Fresno)Despina Sampsonidou ( AUTH) and Claudio Savarese(Napoli Federico
II )
Precision of strips over large area
• 5 PCBs (0.6 x 2 m2) PCBs from ELTOS at CERN.• Measurements to be taken
– position of fiducial marks.– Strip pitch at different positions.
SideA
SideB
Instrument for fiducial measurements
• Traveling Microscope– Microscope that travels on tracks above a table– Digital readout– Measurements can be taken down to 0.01mm (10 μm)– Used on PCB2 and PCB3
Fiducial mark Copper strip
Fiducial results PCB2 – (B)
1 3 5 7 9 11 13 15 17 1924
24.2
24.4
24.6
24.8
25
25.2
25.4
25.6
25.8
26
f(x) = − 0.000253400143163902 x + 24.8755118110236
Distance from Fiducial to Strip
Position
Dis
tanc
e (m
m)
0 2 4 6 8 10 12 14 16 18 2099
99.2
99.4
99.6
99.8
100
100.2
100.4
100.6
100.8
101
f(x) = 0.00152631578947372 x + 99.9526315789474
Fiducial to Fiducial
Dis
tanc
e (m
m)
Position
Results for Fiducial reading
• PCB2 – average fiducial to strip reading of 24.87mm and fiducial to fiducial
reading of 99.97mm for side B.– average fiducial to strip reading of 24.88mm and fiducial to fiducial
reading of 99.97mm for side A.– Average length from strip A edge to strip B edge 500.28mm
• PCB3– average fiducial to strip reading of 24.89mm and fiducial to fiducial
reading of 99.98mm for side B.– average fiducial to strip reading of 24.88mm and fiducial to fiducial
reading of 99.99mm for side A.– Average length from strip A edge to strip B edge 500.33mm
Instrument for Strip pitch
• NA62 laser interferometer– Computer controlled laser that can take reading down to a
nanometer.
laser
Full Scan of PCB1
Full Scan 1
Full Scan 2
Full Scan 3
Finding the pitch
• What is pitch? • Small region analysis of the full data set.
-519.6 -519.4 -519.2 -519 -518.8 -518.6 -518.431.5
31.52
31.54
31.56
31.58
31.6
31.62
31.64
31.66
31.68
31.7
pitch
pitch
Current results Scan 1 Other “big” peaks → multiples of 400μm Other “small” peaks → multiples of 200μm Misidentified local maxima
Current results Scan 2
Gaussian
measurements
Problems
• Some bad fiducial marks/copper strips• Laser would move along the vertical after being set
Conclusion
• The boards are close to uniform with at most a 10μm to 50μm difference.
• Short analyses are promising a pitch of 400μm• About 1250 copper Strips within the 500mm
width of the board.• Work still needs to be done on the remaining
boards and analyses of the full data set need to be completed.