INSPECTION SYSTEM AND METHOD FOR ANALYZING DEFECTS

Abstract

An inspection system and a method for analyzing defects in a product, in particular a printed circuit board product, a semiconductor wafer or the like, the inspection system includes a projection device , an optical detection device , and a processing device, the projection device having an illuminating unit and a spectrometer member configured to split white light into its spectral components and project a multichromatic light beam thus formed from monochromatic light beams onto a product at an angle of incidence , the optical detection device having a detection unit comprising a camera and an objective , the camera being configured to detect the multichromatic light beam reflected on the product in a detection plane of the detection unit, the detection plane being perpendicular, preferably orthogonal, to a product surface of the product, the illuminating unit having at least two light-emitting diodes disposed in a row and an exit aperture extending along the row.

Claims

1. An inspection system (10) for analyzing defects in a product, the inspection system comprising a projection device (11), an optical detection device (12), and a processing device, the projection device having an illuminating unit (16, 26) and a spectrometer member (17) configured to split white light into its spectral components and project a multichromatic light (18) beam thus formed from monochromatic light beams onto a product (19) at an angle of incidence , the optical detection device having a detection unit (13) comprising a camera (14) and an objective (15), the camera being configured to detect the multichromatic light beam reflected on the product in a detection plane (21) of the detection unit, the detection plane being perpendicular to a product surface (20) of the product, wherein the illuminating unit has at least two light-emitting diodes (24, 27) disposed in a row (23) and an exit aperture (25, 42) extending along the row.

2. The inspection system according to claim 1, wherein the illuminating unit (16, 26) is configured to establish a homogenous intensity distribution of the white light along the detection plane (21).

3. The inspection system according to claim 1, wherein the illuminating unit (16, 26) has an LED module (28) comprising a plurality of light-emitting diodes (24, 27), the LED module being disposed parallel to the detection plane (21).

4. The inspection system according to any one of the claim 1, wherein the illuminating unit (16, 26) has respective aperture members (29) associated with the light-emitting diodes (24, 27).

5. The inspection system according to claim 4, wherein the aperture member (29) has a three-dimensional aperture (30) which has a cross section (32) widening from the light-emitting diode (24, 27) in the direction of a beam path (31) of the projection device (11).

6. The inspection system according to claim 5, wherein the respective apertures (30) of the aperture members (29) are adjacent to one another.

7. The inspection system according to claim 5, wherein the aperture (30) has the shape of a pyramid.

8. The inspection system according to claim 5, wherein the aperture (30) is formed by an optical component (33, 34, 35, 36, 37).

9. The inspection system according to claim 5, wherein the aperture (30) is formed by a stack (38) of optical components (33, 34, 35, 36, 37).

10. The inspection system according to claim 1, wherein the illuminating unit (16, 26) has respective lens assemblies (39) associated with the light-emitting diodes (24, 27).

11. The inspection system according to claim 10, wherein the lens assembly (39) has at least two lenses (40, 41) which are configured to converge or focus the white light of the light-emitting diode (24, 27).

12. The inspection system according to claim 10, wherein a focal point of the lens assembly (39) is formed in the exit aperture (25, 42).

13. The inspection system according to claim 1, wherein the exit aperture (25, 42) is formed by an uninterrupted air gap (43).

14. The inspection system according to claim 1, wherein the spectrometer member (17) is disposed adjacent to and immediately downstream of the illuminating unit (16, 26) in the direction of the beam path (31) of the projection device (11).

15. The inspection system according to claim 1, wherein the spectrometer member (17) has at least one diffractive or dispersive optical element which extends parallel to the detection plane (21).

16. The inspection system according to claim 1, wherein the projection device (11) is configured to emit light of the wavelength ranges red, green, blue (RGB), infrared (IR), or ultraviolet (UV), and the camera (14) is configured to detect said light.

17. A method for analyzing defects in a product, the method using an inspection system (10), the inspection system comprising a projection device (11), an optical detection device (12), and a processing device, an illuminating unit (16, 26) and a spectrometer member (17) of the projection device being used to split white light into its spectral components and project a multichromatic light beam (18) thus formed from monochromatic light beams onto a product (19) at an angle of incidence , the optical detection device having a detection unit (13) comprising a camera (14) and an objective (15), a multichromatic light beam being reflected on the product in a detection plane (21) of the detection unit, the detection plane being perpendicular, preferably orthogonal, to a product surface (20) of the product, the light beam being detected by the camera, wherein at least two light-emitting diodes (24, 27) disposed in a row (23) and an exit aperture (25, 42) of the illuminating unit extending along the row are used to establish a homogenous intensity distribution of the white light along the detection plane.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Hereinafter, preferred embodiments of the invention are discussed in more detail with reference to the accompanying drawings.

[0028] FIG. 1 is a simplified schematic illustration of an inspection system in a side view;

[0029] FIG. 2 is a schematic illustration of a projection device in a top view;

[0030] FIG. 3 shows an illuminating unit of the projection device of FIG. 2;

[0031] FIG. 4 is a schematic section view of another illuminating unit.

DETAILED DESCRIPTION

[0032] A combination of FIGS. 1 to 3 shows a simplified schematic diagram of an inspection system 10 comprising a projection device 11, an optical detection device 12, and a processing device (not shown). Detection device 12 has a detection unit 13 comprising a camera 14 and an objective 15. Projection device 11 is composed of an illuminating unit 16 and a spectrometer member 17. Spectrometer member 17 is configured to split white light of illuminating unit 16 into its spectral components so that a multichromatic light beam 18 thus formed from monochromatic light beams can be projected onto a product 19 at an angle of incidence . Light beam 18 is reflected by a product surface 20 of product 19 and runs toward objective 15 in a detection plane 21 of detection unit 13, detection plane 21 being perpendicular, preferably orthogonal, to product surface 20. Consequently, detection plane 21 is perpendicular to a direction of movement of product 19 relative to inspection system 10, the direction of movement being marked by an arrow 22. A height information of product surface 20 relative to camera 14 is derived by means of a processing device (not shown) from a spatial distribution of the reflected multichromatic light beam 18 onto a camera chip (not shown) of camera 14.

[0033] Illuminating unit 16 is provided with a row 23 of light-emitting diodes 24 and extends parallel to detection plane 21. In particular, a homogenous intensity distribution of the white light along detection plane 21 can be established at an exit aperture 25 of illuminating unit 16, exit aperture 25 extending along row 23. Spectrometer member 17 is configured to subsequently split the white light into its spectral components and shape it into multichromatic light beam 18. As can be seen in FIG. 3, a diagrammatically illustrated intensity distribution of the white light is uneven in the area of the light-emitting diodes and even, i.e., homogenous, in the area of exit aperture 25.

[0034] FIG. 4 shows a schematic illustration of another embodiment of an illuminating unit 26, which could also be employed in the inspection system described above. Illuminating unit 26 has light-emitting diodes 27 of an LED module 28, which are disposed in a row and spaced apart relative to each other. Each light-emitting diode 27 is associated with an aperture member 29, which is formed by a three-dimensional aperture 30. Aperture 30 has a cross section 32, which widens from light-emitting diode 27 in the direction of a beam path 31 of illuminating unit 26. In particular, aperture 30 is pyramidal. Furthermore, aperture 30 is formed by plane plates 33 to 37, which form a stack 38. Each light-emitting diode 27 is associated with a lens assembly 39, which comprises lenses 40 and 41 in the case at hand. Lens assembly 39 serves to converge and focus the white light of light-emitting diodes 27. A focal point of lens assembly 39 is formed in an exit aperture 42 of illuminating unit 26. Exit aperture 42 is formed by an uninterrupted air gap 43, which is hinted at in the drawings. The structure of illuminating unit 26 enables the production of white light with a homogenous intensity distribution along exit aperture 42. Consequently, a multichromatic light beam with a correspondingly homogenous intensity distribution can be formed on a product surface (not shown) of a product via a downstream spectrometer member.

Reference Signs

[0035] 10 inspection system [0036] 11 projection device [0037] 12 optical detection device [0038] 13 detection unit [0039] 14 camera [0040] 15 objective [0041] 16 illuminating unit [0042] 17 spectrometer member [0043] 18 light beam [0044] 19 product [0045] 20 product surface [0046] 21 detection plane [0047] 22 arrow [0048] 23 row [0049] 24 light-emitting diode [0050] 25 exit aperture [0051] 26 illuminating unit [0052] 27 light-emitting diode [0053] 28 LED module [0054] 29 aperture member [0055] 30 aperture [0056] 31 beam path [0057] 32 cross section [0058] 33 to 37 plane plate [0059] 38 stack [0060] 39 lens assembly [0061] 40 lens [0062] 41 lens [0063] 42 exit aperture [0064] 43 air gap