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Page 1
The Effect of Process Equipment on
Fine-Line Uniformity
March 25, 2003
Page 2
Preface
Test patternsUniformity issuesPhotoplotter resolutionLaser direct imagingEtching uniformity
Page 3
Conductor/Space Panels
Page 4
Conductor/Space Modules
Design1 inch by 1 inch4 conductors and 3 spacesSelectable conductor and space sizes
AnalysisYields and defect densitiesPredicted product yieldsConductor width and height uniformityProcess capability (Cp, Cpk)
Page 5
Conductor Width and Height
Average conductor width over its lengthAverage conductor height over the module
width
height
Page 6
Uniformity Issues
Types of non-uniformities
Feature orientationPanel surfaceSide-to-sidePanel-to-panelLot-to-lot
Sources of non-uniformities
ArtworkImagingDevelopingEtching
Page 7
Photoplotter Test
18 x 24 inch panels1-oz copperPrint and etch[3] 4 [4] 5 [5] 6 [6] [conductor] spaceConstant process conditions
Page 8
Photo-Plotter Resolution
8,000
8,000
20,000
Resolution (DPI)
0.1561.031.69B
0.0950.661.61A
0.0860.491.76A
Std. Dev. (mils)
Range (mils)
Mean (mils)Plotter
Page 9
Plotter A at 20,000 DPI
Surface Std. Dev. = 0.086 milsSurface Range = 0.41 mils
Page 10
Plotter A at 8,000 DPI
Surface Std. Dev. = 0.091 milsSurface Range = 0.51 mils
Page 11
Plotter B at 8,000 DPI
Surface Std. Dev. = 0.148 milsSurface Range = 0.856 mils
Page 12
Laser Direct Imaging Test
18 x 24 inch panels0.5-oz copperPrint and etch[2] 2 [3] 3 [4] 4 [5] [conductor] spaceSingle-sided exposure
Page 13
LDI Top Side
Page 14
LDI Bottom Side
Page 15
Etching Non-Uniformities
PuddlingStripingDirectional dependenceEdge dependenceCombinations
Page 16
Puddling
Page 17
Striping
Page 18
Directional Dependence
Page 19
Edge Dependence
Page 20
Puddling and Striping
Page 21
Puddling and Directional
Page 22
Directional and Edge
Page 23
Etching Uniformity
Improvements are possibleCooperation between equipment manufacturer and PCB fabricator is critical
Page 24
Top Side - Initial
Surface Std. Dev. = 0.110 milsSurface Range = 0.57 mils
Page 25
Top Side - Final
Surface Std. Dev. = 0.079 milsSurface Range = 0.46 mils
Page 26
Bottom Side - Initial
Surface Std. Dev. = 0.160 milsSurface Range = 0.74 mils
Page 27
Bottom Side - Final
Surface Std. Dev. = 0.071 milsSurface Range = 0.40 mils
Page 28
Final Thoughts
Uniformity improvements are essential forcontrolled impedance productshigh-density products
Etching is not the only source of non-uniformitiesProcess non-uniformities can cause opens and shortswww.cat-test.info
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