EP0160781A1
Expired / Lapsed
EP
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Measuring and detecting printed circuit wiring defects
Assignee: International Business Machines Corp
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Filing: 1985-02-01
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Granted: —
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Expires: 2005-02-01
Abstract
Abstract A non-contact system for detecting printed circuit wiring defects and for measuring circuit feature height relative to a substrate. The system has an energy source (32) for illuminating at an angle the substrate (30) and circuit features (31) and a scanner (36, 38) for both instantaneously receiving energy reflected from the substrate and circuit features and for generating a plurality of signals in response to the reflected energy, which signals are adapted to vary with the intensities of the locally reflected energies. An analyzer is connected to the scanner for correlating the generated signals to a measurement representative of the height of the circuit features relative to the substrate. Variations and non-uniformity of the substrate surface due to bending. warpage or other causes can be accounted for so as to provide an accurate measurement of the height of a circuit feature relative to the substrate surface on which it is mounted.
Inventors
- 👤 Robert M. Crabb
- 👤 Steven M. Defoster
- 👤 Norman E. Rittenhouse
- 👤 Mark A. West
- 👤 Richard A. Ziegler
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 13:03
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/28; G01R31/302; G01R31/308; G01R31/309; G01B; G01B11/00; G01B11/24; G01B11/25; G01B11/2518; G01B11/2522; G01N; G01N21/00; G01N21/84; G01N21/88; G01N21/95; G01N21/956; G01N21/95684; G01R31/2801; G01R31/2806
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
141 words
A non-contact system for detecting printed circuit wiring defects and for measuring circuit feature (31, 50) height relative to a substrate (30, 52) characterized by: a) an energy source (100, 32, 104) for locally illuminating (34, 54, 56) said substrate (30) and circuit features thereon at a predetermined angle of incidence; b) scanning means (36, 38) disposed proximate said substrate and circuit features thereon and operatively related thereto, said scanning means being adapted for: i) substantially instantaneously receiving energy reflected from said substrate and circuit features thereon; and ii) generating a signal in response thereto, said signal being adapted to vary with the intensity of said reflected energy; and c) analyzing means (112-118) operatively connected to said scanning means for correlating said signal received therefrom to a measurement representative of height of said circuit features on said substrate and relative thereto.
Claim 2
Dependent Claim
141 words
A non-contact system for detecting printed circuit wiring defects and for measuring circuit feature (31, 50) height relative to a substrate (30, 52) characterized by: a) an energy source (100, 32, 104) for locally illuminating (34, 54, 56) said substrate (30) and circuit features thereon at a predetermined angle of incidence; b) scanning means (36, 38) disposed proximate said substrate and circuit features thereon and operatively related thereto, said scanning means being adapted for: i) substantially instantaneously receiving energy reflected from said substrate and circuit features thereon; and ii) generating a signal in response thereto, said signal being adapted to vary with the intensity of said reflected energy; and c) analyzing means (112-118) operatively connected to said scanning means for correlating said signal received therefrom to a measurement representative of height of said circuit features on said substrate and relative thereto.
Claim 3
Dependent Claim
22 words
The system in accordance with claim 1 wherein said energy source is a laser and said scanning means is an electro-optical device.
Claim 4
Dependent Claim
45 words
The system in accordance with claim 2 wherein said energy source comprises cylindrical optics (32) to project a slit of light onto said substrate (30) and said electro-optical device (38) is a linear charge coupled device (linear CCD) having a plurality of elements disposed therein.
Claim 5
Dependent Claim
40 words
The system in accordance with claim 3 wherein said linear CCD receives energy reflected from a predetermined area (34, 54, 56) on said substrate and circuit features thereon and wherein said plurality of CCD elements are individually and simultaneously activated.
Claim 6
Dependent Claim
53 words
The system in accordance with claim 4 wherein the energy received by each of said plurality of CCD elements is individually and independently analyzed for a predetermined number of cycles corresponding to different height levels relative to a base level (I) so that non-linearities on said substrate and circuit features thereon are detected.
Claim 7
Dependent Claim
24 words
The system in accordance with claim 1 further comprising: d) positioning means (106) for moving said scanning means (32-38) relative to said substrate (30).
Claim 8
Dependent Claim
51 words
The system in accordance with claim 1 wherein said analyzing means comprises a first memory (118) for storing data representative of said signal generated by said scanning means, and said analyzing means comprises a second memory (124, 126) for storing analyzed data representative of the height dimensions of said circuit features.
Claim 9
Dependent Claim
32 words
The system in accordance with claim 7 wherein said analyzing means further comprises means (120) for using said data stored in said first memory to calculate the height of said circuit features.
Claim 10
Dependent Claim
91 words
The system in accordance with claim 1 wherein said analyzing means (112) is adapted to detect three categories of reflected energy intensity, said categories being bounded and defined by two threshold levels (114, 116), where one of said threshold levels separates the intensity of background energy from the intensity of energy reflected from said substrate, and the other one of said threshold levels separates the intensity of energy reflected from said substrate from the intensity of energy reflected from said circuit features, whereby the presence of said circuit features is detected.
Claim 11
Dependent Claim
38 words
The system in accordance with claim 1 or 5 further comprising: e) means (104) for moving said energy discretely through a plurality of focal planes over at least the field of view relative to said scanning means (38).
Claim 12
Dependent Claim
17 words
The system in accordance with claim 10 wherein said energy moving means is an acousto-optic modulating device.
Claim 13
Independent Claim
199 words
A method for detecting printed circuit wiring defects and measuring the height of the upper surface of a circuit feature relative to a substrate upper surface, characterized by the steps of: a) projecting energy locally at an angle onto said substrate and circuit feature thereon; b) providing a scanning means for receiving reflected energy; c) moving the energy relative to said substrate such that said energy is in focus at an initial or base focal plane below the upper surface of said substrate and substantially parallel thereto, relative to said scanning means; d) generating a signal in response to said reflected energy, said signal adapted to vary with the intensity thereof; e) correlating said signal to a reference level of intensity representative of surface reflectivity; f) moving said energy relative to said substrate such that said energy is in focus at a plane above said initial focal plane and substantially parallel thereto; g) repeating steps (d) through (f) until the focused plane is above the level of the upper surface of said circuit feature; and h) correlating said signals generated in step (e) to measurements representative of the height of said circuit features and any printed circuit wiring defects.
Claim 14
Independent Claim
199 words
A method for detecting printed circuit wiring defects and measuring the height of the upper surface of a circuit feature relative to a substrate upper surface, characterized by the steps of: a) projecting energy locally at an angle onto said substrate and circuit feature thereon; b) providing a scanning means for receiving reflected energy; c) moving the energy relative to said substrate such that said energy is in focus at an initial or base focal plane below the upper surface of said substrate and substantially parallel thereto, relative to said scanning means; d) generating a signal in response to said reflected energy, said signal adapted to vary with the intensity thereof; e) correlating said signal to a reference level of intensity representative of surface reflectivity; f) moving said energy relative to said substrate such that said energy is in focus at a plane above said initial focal plane and substantially parallel thereto; g) repeating steps (d) through (f) until the focused plane is above the level of the upper surface of said circuit feature; and h) correlating said signals generated in step (e) to measurements representative of the height of said circuit features and any printed circuit wiring defects.
Claim 15
Dependent Claim
36 words
The method in accordance with claim 12, further comprising the step of storing a reflected energy value representative of the location of the focused plane relative to said initial focal plane for each plane scanned thereby.
Claim 16
Dependent Claim
62 words
The method in accordance with claim 13, further comprising the step of subtracting the value representative of the focal plane at the upper surface of said substrate from the value representative of the focal plane at the upper surface of said circuit feature to obtain a value representative of the height of the upper surface thereof relative to said upper substrate surface.
References Cited (Backward Citations)
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