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WO2009038242A1 - Procédé de test optique - Google Patents

Procédé de test optique Download PDF

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Publication number
WO2009038242A1
WO2009038242A1 PCT/KR2007/004483 KR2007004483W WO2009038242A1 WO 2009038242 A1 WO2009038242 A1 WO 2009038242A1 KR 2007004483 W KR2007004483 W KR 2007004483W WO 2009038242 A1 WO2009038242 A1 WO 2009038242A1
Authority
WO
WIPO (PCT)
Prior art keywords
image
target object
defect
absence
test surface
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/KR2007/004483
Other languages
English (en)
Inventor
Ssang-Geun Im
Sang-Yun Lee
Mingu Kang
Seok-Joon Jang
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Intekplus Co Ltd
Original Assignee
Intekplus Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Intekplus Co Ltd filed Critical Intekplus Co Ltd
Priority to PCT/KR2007/004483 priority Critical patent/WO2009038242A1/fr
Publication of WO2009038242A1 publication Critical patent/WO2009038242A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/8806—Specially adapted optical and illumination features
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N21/956—Inspecting patterns on the surface of objects
    • G01N21/95684—Patterns showing highly reflecting parts, e.g. metallic elements

Definitions

  • the present invention relates to an optical test method, and more particularly to an optical test method for acquiring an image where a lattice image is clearly shown on a test surface on which illumination saturation occurs by a regular reflection, thereby increasing test reliability.
  • semiconductor devices have been widely used as important components for computers or household appliances, so that they must pass complicated tests before coming into the market.
  • the semiconductor devices require high precision superior to those of other components. If any defect occurs in internal elements or outer appearance of the semiconductor package, the defect has a negative influence upon the performance or throughput of the semiconductor package .
  • the external appearance defect of the semiconductor device may occur during the assembling process between the semiconductor device and a PCB circuit, so that the process for testing the lead- or ball- status of the semiconductor device such as a QPF or BGA has been considered to be one of the principal processes .
  • an optical method for measuring a three-dimensional shape which configures a reference pattern for an optical signal, generated from the light source, applies the optical signal to a target object to be measured, compares the optical signal modified by the shape of the target object with the reference pattern, and measures the shape of the target object to be measured, so that the three-dimensional shape of the target object is measured.
  • the above-mentioned optical method for measuring the three-dimensional shape requires a high speed, a high precision, and non-contact measurement.
  • a representative example of the above-mentioned optical method for measuring the three-dimensional shape is an optical method for measuring a three-dimensional shape using a moire pattern.
  • the moire pattern is indicative of an interference pattern formed when at least two periodic patterns overlap with each other.
  • the moire scheme is classified into a shadow moire scheme and a projection moire scheme according to methods for forming the moire pattern.
  • the projection moire scheme applies an optical signal or light beam to a target object to be measured, so that it applies a lattice pattern on the target object.
  • the projection moire scheme allows a lattice image modified by the shape of the target object to overlap with a reference lattice having the same pitch as that of the lattice providing the lattice image, so that it can acquire the moire pattern.
  • the above-mentioned optical method for measuring the three-dimensional shape has a disadvantage in that it has difficulty in accurately acquiring the image of a regular reflection surface by the regular reflection of a three-dimensional surface.
  • the present invention has been made in view of the above problems, and it is an object of the invention to provide an optical test method for arranging several white lights and filters having different wavelengths in the individual white lights, adjusting a wavelength of a light signal illuminated on the target object by adjusting a brightness of each white light, acquiring a color image, calculating phases for every color wavelength on the basis of the acquired image, adding the individual phases, and calculating the added result as a single phase, so that it can acquire an accurate image of the target object to be tested.
  • an optical test method which captures an external appearance image of a target object to be tested, analyzes the captured image, and determines the presence or absence of a defect in the target object according to the analyzed result, the method comprising: mounting different band pass filters (BPFs) to several white lights, respectively, reducing a saturation area of a test surface of the target object by adjusting a brightness of each white light, and illuminating an illumination light signal on the test surface to acquire a wavelength band on which a lattice image is clearly shown; capturing the test surface, and acquiring a color image; dividing the acquired color image into several wavelengths, and calculating individual phases of the divided images at the wavelengths; and adding the calculated phases, calculating the added result as a single phase, analyzing the calculated single phase, and determining the presence or absence of a defect.
  • BPFs band pass filters
  • an optical test method which captures an external appearance image of a target object to be tested, analyzes the captured image, and determines the presence or absence of a defect in the target object according to the analyzed result, the method comprising: illuminating a white light on a test surface of the target object; reducing a saturation area of the test surface by adjusting gains of several wavelengths of a color camera, capturing the test surface, and acquiring a color image; dividing the acquired color image into several wavelengths, and calculating individual phases of the divided images at the wavelengths; and adding the calculated phases, calculating the added result as a single phase, analyzing the calculated single phase, and determining the presence or absence of a defect.
  • FIG. 1 is a flow chart illustrating an optical test method according to an embodiment of the present invention
  • FIG. 2 is a schematic diagram illustrating an optical test apparatus for use in the optical test method according to an embodiment of the present invention
  • FIG. 3 is a flow chart illustrating an optical test method according to another embodiment of the present invention.
  • FIG. 4 is a schematic diagram illustrating an optical test apparatus for use in the optical test method according to another embodiment of the present invention.
  • FIG. 1 is a flow chart illustrating an optical test method according to an embodiment of the present invention.
  • the optical test method according to the present invention captures an external appearance image of the target object, analyzes the captured image, and determines the presence or absence of a defect in the target object according to the analyzed result.
  • the above-mentioned optical test method mounts different band pass filters (BPFs) to several white lights, respectively, reduces a saturation area of the target object by adjusting a brightness of each white light, and illuminates an illumination light signal on a test surface to acquire a wavelength band on which the lattice image is clearly shown at step SlO.
  • BPFs band pass filters
  • the optical test method divides the acquired color image into several wavelengths, and calculates individual phases of the divided images at the wavelengths at step S30.
  • the optical test method adds the calculated phases, calculates the added result as a single phase, analyzes the calculated single phase, and determines the presence or absence of a defect at step S40.
  • the different BPFs may be implemented with color filters or polarizing filters. If the BPFs are implemented with the color filters, a red filter, a green filter, and a blue filter may be used as the different BPFs.
  • different BPFs are mounted to at least two white lights, respectively, the saturation area of the target object to be tested is reduced by adjustment of the brightness (i.e., an illumination value) of each white light, so that a color image of a corresponding test surface is acquired.
  • the color image is divided into several wavelengths, and the divided images are mixed with each other, so that the presence or absence of a defect in the target object is determined according to the mixed result.
  • E -1 IG. 2 is a schematic diagram illustrating an optical test apparatus for use in the optical test method according to an embodiment of the present invention.
  • the optical test apparatus includes an illumination unit 1, a target object 2 to be tested, an image-capturing unit 3, and an analyzing unit 4.
  • the illumination unit 1 acts as a unit for illuminating an optical signal on a test surface of the target object 2.
  • the illumination unit 1 includes a plurality of white lights 11a, lib and lie, a plurality of BPFs 111, 112, and 113 contained in the individual white lights 11a, lib, and lie, a lattice unit 12, a projection optical system 13, and a reflection mirror 14, etc.
  • the BPFs 111, 112, and 113 may be implemented with color filters or polarizing filters. If the BPFs are implemented with the color filters, R-, G-, and B- filters may be used as the above-mentioned BPFs.
  • the target object 2 may be a semiconductor package equipped with balls. Although the semiconductor package is not shown in the drawings, it is delivered and arranged on a test table.
  • the image-capturing unit 3 is used as an image pickup element for capturing an image reflected from the surface of the target object 2.
  • the image-capturing unit 3 includes a CCD camera 32 and an image optical system 31 for focusing the light on the CCD camera, and transmits the image captured by the CCD camera 32 to the analyzing unit 4.
  • the analyzing unit 4 analyzes the received signal, compares the analyzed image with a reference image, and determines the presence or absence of a defect in a corresponding target object according to the comparison result.
  • the analyzing unit 4 may be implemented with a computer.
  • a light or optical signal is illuminated on the test surface using the white lights 11a, lib, and lie.
  • a saturation area of the test surface is reduced, and a wavelength band is adjusted to clearly show the lattice pattern.
  • the wavelength band can also be adjusted.
  • a blue wavelength band is appropriate for the central rounding surface of each ball so that regular reflection points are removed from the central rounding surface of the ball.
  • the green wavelength is the most suitable for clearly showing the lattice pattern on the bottom. Therefore, the light quantity of the blue-filter white light must increase at the ball's central rounding surface during the illumination process, and the light quantity of the green-filter white light must increase at the bottom surface.
  • the illuminated light signal passes through the lattice unit 12.
  • the light signal generated from the lattice unit 12 is focused as a lattice pattern on the test surface .
  • the image of the test surface of the target object to be tested is captured by the CCD color camera 32, and analog signals of the captured image are converted into digital signals via a frame grabber, so that the color image is acquired.
  • the analyzing unit 4 divides the color image acquired via the frame grabber into red, green, and blue wavelength bands, and calculates the phases of images for every wavelength band.
  • the analyzing unit 4 adds the calculated phases, calculates the added result as a single phase, compares the calculated phase with a reference phase, and determines the presence or absence of a defect in the target object according to the comparison result.
  • the above-mentioned optical test method properly adjusts the wavelength bands of the individual white lights to reduce the number of regular reflection points on the regular reflection surface, and increases the accuracy of the captured image, resulting in increased test reliability.
  • the reducing of the regular reflection points on the regular reflection surface may be equal to the reducing of the illumination saturation area of the test surface.
  • FIG. 3 is a flow chart illustrating an optical test method according to another embodiment of the present invention.
  • the optical test method according to another embodiment of the present invention captures an external appearance image of the target object, analyzes the captured image, and determines the presence or absence of a defect in the target object according to the analyzed result.
  • the above-mentioned optical test method illuminates the white light on the test surface at step SlOO.
  • the optical test method reduces a saturation area of the target surface by adjusting gains of several wavelength bands of the color camera, captures the test surface, and acquires a color image at step S200.
  • the optical test method divides the acquired color image into several wavelengths, and calculates individual phases of the divided images at the wavelengths at step S300.
  • the optical test method adds the calculated phases, calculates the added result as a single phase, analyzes the calculated single phase, and determines the presence or absence of a defect at step S400.
  • the different BPFs may be implemented with color filters or polarizing filters. If the BPFs are implemented with the color filters, a red filter, a green filter, and a blue filter may be used as the different BPFs.
  • FIG. 4 is a schematic diagram illustrating an optical test apparatus for use in the optical test method according to another embodiment of the present invention. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
  • the optical test apparatus includes an illumination unit 1, a target object 2 to be tested, an image-capturing unit 3, and an analyzing unit 4.
  • the illumination unit 1 acts as a unit for illuminating an optical signal on the target object 2 such as a semiconductor package equipped with balls.
  • the illumination unit 1 includes a white light 11, a lattice unit 12, a projection optical system 13, and a reflection mirror 14, etc.
  • the target object is not shown in FIG. 4, it is delivered and arranged on a test table.
  • the image-capturing unit 3 is used as an image pickup element for capturing an image reflected from the surface of the target object 2.
  • the image-capturing unit 3 includes a CCD camera 32 and an image optical system 31 for focusing the light on the CCD camera, and transmits the image captured by the CCD camera 32 to the analyzing unit 4. If an analog signal of the image captured by the image-capturing unit 3 is converted into a digital signal via a frame grabber and the digital signal is applied to the analyzing unit 4, the analyzing unit 4 analyzes the received signal, compares the analyzed image with a reference image, and determines the presence or absence of a defect in a corresponding target object according to the comparison result.
  • the analyzing unit 4 may be implemented with a computer.
  • the optical test method adjusts the light quantity of the white light 11 on the test surface (i.e., the surface of the target object.
  • the illuminated optical signal passes through the lattice unit 12, and the light signal generated from the lattice unit 12 is focused as a lattice pattern on the test surface .
  • the image of the test surface of the target object to be tested is captured by the CCD color camera 32, and analog signals of the captured image are converted into digital signals via the frame grabber, so that the color image is acquired.
  • the most important duty of the above- mentioned operations is to acquire the image by adjusting a gain of each wavelength band of the CCD color camera while the image is captured by the CCD color camera.
  • the gain of a specific wavelength band is adjusted to reduce an illumination saturation area of the test surface of the target object, so that a color image capable of clearly showing the lattice pattern on all areas should be acquired.
  • the analyzing unit 4 divides the color image acquired via the frame grabber into red, green, and blue wavelength bands, and calculates the phases of images for every wavelength band.
  • the analyzing unit 4 adds the calculated phases, calculates the added result as a single phase, compares the calculated phase with a reference phase, and determines the presence or absence of a defect in the target object according to the comparison result.
  • the above- mentioned optical test method adjusts a gain of a specific wavelength band of a color camera to reduce saturation areas of all the areas of the test surface, and acquires a color image, so that it increases the accuracy of the captured image, resulting in increased test reliability.
  • the optical test method arranges several white lights and BPFs having different wavelengths in the individual white lights, adjusts a brightness of each white light, provides an illumination light signal having a wavelength band adjusted to reduce an illumination saturation area of a 3D surface, acquires a color image using the illumination light signal, calculates phases for every color wavelength on the basis of the acquired color image, adds the individual phases, and calculates the added result as a single phase.
  • the optical test method reduces the number of regular reflection points on the 3D surface, and acquires the accurate image, resulting in increased test reliability.
  • the optical test method illuminates the white light on the target object, reduces an illumination saturation area by adjusting a gain of a specific wavelength of the color camera, acquires a color image, calculates phases of individual color wavelengths on the basis of the acquired image, adds the individual phases, and calculates the added result as a single phase, so that it can clearly show the lattice pattern on all the areas of the target object, resulting in increased test reliability.
  • the optical test method uses a single illumination device, so that it does not make the configuration complicated, resulting in reduction of production costs and installation space of the apparatus associated with the test method.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)

Abstract

Selon l'invention, un procédé de test optique capture une image d'apparence extérieure d'un objet cible, analyse l'image capturée, et détermine la présence ou l'absence d'un défaut dans l'objet cible en fonction du résultat de l'analyse. Le procédé de test optique associe plusieurs BPF à plusieurs lumières blanches, envoie un signal lumineux d'éclairage sur la surface de test afin d'acquérir une bande de longueur d'onde sur laquelle une image réticulaire apparaît clairement, divise l'image couleur acquise en plusieurs longueurs d'onde, calcule des phases individuelles des images divisées selon les longueurs d'onde, ajoute les phases calculées, calcule le résultat ajouté en tant que phase unique, analyse la phase unique calculée, et détermine la présence ou l'absence d'un défaut.
PCT/KR2007/004483 2007-09-18 2007-09-18 Procédé de test optique Ceased WO2009038242A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/KR2007/004483 WO2009038242A1 (fr) 2007-09-18 2007-09-18 Procédé de test optique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/KR2007/004483 WO2009038242A1 (fr) 2007-09-18 2007-09-18 Procédé de test optique

Publications (1)

Publication Number Publication Date
WO2009038242A1 true WO2009038242A1 (fr) 2009-03-26

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PCT/KR2007/004483 Ceased WO2009038242A1 (fr) 2007-09-18 2007-09-18 Procédé de test optique

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6181430B1 (en) * 1999-03-15 2001-01-30 Ohio Aerospace Institute Optical device for measuring a surface characteristic of an object by multi-color interferometry
US6690466B2 (en) * 1999-08-06 2004-02-10 Cambridge Research & Instrumentation, Inc. Spectral imaging system
US6750975B2 (en) * 2001-04-20 2004-06-15 Teruki Yogo Three-dimensional shape measuring method
US7019848B2 (en) * 2002-02-01 2006-03-28 Ckd Corporation Three-dimensional measuring instrument, filter striped plate, and illuminating means

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6181430B1 (en) * 1999-03-15 2001-01-30 Ohio Aerospace Institute Optical device for measuring a surface characteristic of an object by multi-color interferometry
US6690466B2 (en) * 1999-08-06 2004-02-10 Cambridge Research & Instrumentation, Inc. Spectral imaging system
US6750975B2 (en) * 2001-04-20 2004-06-15 Teruki Yogo Three-dimensional shape measuring method
US7019848B2 (en) * 2002-02-01 2006-03-28 Ckd Corporation Three-dimensional measuring instrument, filter striped plate, and illuminating means

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