JP5571972B2 - Inspection device and inspection method for printed circuit board - Google Patents

Description

  The present invention relates to an inspection apparatus and a method for inspecting a printed circuit board, and more particularly to an inspection apparatus used for inspecting the presence or absence of a foreign substance in a cover insulating layer in a printed circuit board, and a method for inspecting a printed circuit board using the inspection apparatus .

  Conventionally, a wired circuit board such as a suspension board with circuit includes a metal support layer and a base insulating layer, a conductor pattern, and a cover insulating layer, which are sequentially stacked thereon. In such a printed circuit board, when a conductive foreign substance exists in the insulating cover layer and it extends between the conductor patterns, the conductor pattern is short-circuited, so that the connection reliability is lowered. Therefore, the presence / absence of the foreign matter is inspected.

  In such an inspection, an apparatus for determining whether or not there is a foreign object by using inspection light incident on a printed circuit board and detecting inspection light reflected therefrom is used.

  For example, an automatic optical inspection apparatus (AOI) that inspects a conductor pattern is used before the insulating cover layer is formed, and the entire appearance of the printed circuit board is inspected after the insulating cover layer is formed. An automatic visual inspection apparatus (AVI: Automatic Visual Inspection) is used.

  And as an inspection apparatus that can be used for the above-mentioned AVI, for example, an insulating film, a wiring pattern formed thereon, and a long film carrier tape provided with a coverlay layer covering the insulating film are arranged opposite to each other. An inspection apparatus including an upper irradiation unit, a horizontal irradiation unit, and a microscope has been proposed (see, for example, Patent Document 1).

  In this inspection apparatus, the upper irradiation means is formed as a ring light using an LED as a light source, and irradiates the film carrier tape with irradiation light so that the incident angle with respect to the vertical direction is 3 to 45 degrees. Yes.

  Further, the horizontal irradiation means is formed of a pair of fluorescent lamps that extend linearly along the longitudinal direction and are opposed to each other at an interval in a direction orthogonal to the longitudinal direction, with respect to the film carrier tape. The diffused light is irradiated so as to diffuse.

  In this inspection apparatus, the film carrier tape is inspected by irradiating the film carrier tape with the above-mentioned irradiation light and diffused light, and reading the reflected light reflected by them with a microscope.

  That is, in the inspection apparatus described in Patent Document 1, the ring light causes the irradiated light to enter the film carrier tape at a relatively small incident angle with respect to the vertical direction, and the fluorescent lamp causes the diffused light to be diffused into the film. It is incident on the carrier tape.

JP 2007-42956 A

  However, when the ring light described in Patent Document 1 enters the coverlay layer at a relatively small incident angle with respect to the vertical direction, the ring light corresponds to a foreign substance out of the reflected light reflected on the surface of the coverlay layer. All the reflected light from the upper surface of the raised portion formed in this way, the peripheral edge thereof, and the surface of the cover insulating layer other than the raised portion is received by the light receiving portion.

  For this reason, the received reflected light cannot form a contrast corresponding to the foreign matter, and as a result, there is a problem that the presence or absence of the foreign matter cannot be accurately inspected.

  An object of the present invention is to provide an inspection apparatus and a method for inspecting a printed circuit board that can accurately inspect for the presence or absence of foreign matter in a cover insulating layer.

  In order to achieve the above object, an inspection apparatus of the present invention is configured to cover a base insulating layer, a conductor pattern formed on the base insulating layer, and the conductor pattern on the base insulating layer. An inspection apparatus for inspecting the presence or absence of foreign matter in the insulating cover layer in a printed circuit board including the insulating cover layer to be formed, the light emitting unit for emitting incident light incident on the insulating cover layer, A light receiving portion that is disposed above the printed circuit board and receives the reflected light reflected by the surface of the insulating cover layer, and the light emitting portion includes an optical axis thereof and an upper surface of the insulating base layer. The incident light is emitted so that the angle formed by is less than 30 degrees.

  In the inspection apparatus of the present invention, it is preferable that a plurality of the light sources of the light emitting unit are arranged in a ring shape.

  In the inspection apparatus of the present invention, it is preferable that the incident light has directivity.

  In addition, the inspection apparatus of the present invention is preferably used for the inspection of the presence or absence of foreign matter in the insulating cover layer in the printed circuit board including the insulating cover layer having a thickness of 50 μm or less.

  Moreover, it is suitable for the inspection apparatus of this invention to test | inspect the quality of the said conductor pattern.

  Moreover, it is suitable for the inspection apparatus of this invention to be used for the inspection of the quality of the said conductor pattern in the said wiring circuit board provided with the said conductor pattern whose thickness is 3 micrometers or more.

  In the inspection apparatus of the present invention, it is preferable that the incident light has a wavelength of 450 to 750 nm.

  The wired circuit board inspection method of the present invention is characterized in that the presence or absence of foreign matter in the insulating cover layer on the wired circuit board is inspected using the above-described inspection apparatus.

  In the inspection apparatus of the present invention, the light emitting unit causes incident light to be incident on the surface of the insulating cover layer so that the angle between the optical axis of the light source and the upper surface of the base insulating layer is a low angle within a specific range. The reflected light reflected at the peripheral end portion of the upper surface of the raised portion of the insulating cover layer formed corresponding to is received by the light receiving portion. On the other hand, the reflected light reflected on the upper surface of the raised portion and the surface of the cover insulating layer other than the raised portion is less likely to be received by the light receiving portion.

  Therefore, the reflected light received by the light receiving unit can form a contrast corresponding to the foreign matter, and as a result, the presence or absence of the foreign matter can be accurately inspected.

FIG. 1 is a schematic configuration diagram of an embodiment of an inspection apparatus according to the present invention. FIG. 2 is a perspective view of a light emitting unit of the inspection apparatus shown in FIG. 3 is a cross-sectional view of the suspension board with circuit inspected by the inspection apparatus of FIG. FIG. 4 is a cross-sectional view of a suspension board with circuit in which foreign matter is present in the insulating cover layer and the conductor pattern is short-circuited and disconnected. FIG. 5 is an image processing diagram of Example 1 (an aspect in which the angle formed by the optical axis of the light source and the upper surface of the base insulating layer is 25 degrees). FIG. 6 is an image processing diagram of Comparative Example 1 (an aspect in which the angle formed by the optical axis of the light source and the upper surface of the base insulating layer is 60 degrees). FIG. 7 is an image processing diagram of Comparative Example 2 (an aspect in which the angle formed by the optical axis of the light source and the upper surface of the base insulating layer is 50 degrees).

  1 is a schematic configuration diagram of an embodiment of an inspection apparatus according to the present invention, FIG. 2 is a perspective view of a light emitting unit of the inspection apparatus shown in FIG. 1, and FIG. 3 is with a circuit to be inspected by the inspection apparatus of FIG. FIG. 4 is a cross-sectional view of the suspension board, and FIG. 4 is a cross-sectional view of the suspension board with circuit in which foreign matter is present in the insulating cover layer and the conductor pattern is short-circuited and disconnected.

  In FIG. 1, the front side of the page is “right side”, the back side of the page is “left side”, the left side of the page is “front side”, the right side of the page is “rear side”, the upper side of the page is “upper side”, and the lower side of the page is “lower side”. Side ". Moreover, each direction in FIGS. 2-4 shall be based on the above-mentioned direction of FIG.

  In FIG. 1, this inspection apparatus 1 inspects the presence / absence of a foreign substance 10 (see FIG. 4) in a cover insulating layer 24 and the quality of a conductor pattern 23 (see FIGS. 3 and 4) in a suspension board with circuit 20. AVI (Automatic Visual Inspection). The inspection apparatus 1 is provided so that the suspension board with circuit 20 is conveyed (described later) from the rear side to the front side in the inspection.

  The inspection apparatus 1 employs a detection method using ring illumination, is disposed on the upper side of the suspension board with circuit 20, and includes a light emitting unit 2, a light receiving unit 4, and a support base 5.

  The light emitting unit 2 is disposed on the upper side of the support base 5, specifically, is disposed on the upper side of the suspension board with circuit 20 with a space therebetween, and includes a support cylinder 19 and a light source 3 supported by the support cylinder 19. .

  As shown in FIGS. 1 and 2, the support cylinder 19 has an annular shape. Specifically, the support cylinder 19 is formed in a substantially cylindrical shape having an axis extending in the vertical direction and having both upper and lower sides open. In addition, the support cylinder 19 is formed in an inclined shape in a cross-sectional view along the vertical direction, and more specifically, is formed in a tapered shape that increases in diameter as it goes downward.

  The light source 3 is provided to allow the incident light 7 to be incident on the cover insulating layer 24 of the suspension board with circuit 20, and a plurality of light sources 3 are arranged in a ring shape. Specifically, the light source 3 is provided on the inner side surface of the support cylinder 19 and is aligned in the circumferential direction and the vertical direction of the support cylinder 19. The light source 3 is supported by the support cylinder 19 such that the light emitting surface (light emission port) faces inward (the axis of the support cylinder 19). Furthermore, each light source 3 is arranged symmetrically with respect to the axis of the support cylinder 19.

  As the light source 3, for example, a lamp capable of emitting light having directivity (incident light) is used, and preferably a light emitting diode (LED) is used.

  The wavelength of the incident light 7 emitted from the light source 3 is, for example, 450 to 750 nm, preferably 550 to 750 nm.

  The light receiving unit 4 is disposed on the upper side of the suspension board with circuit 20 with a space therebetween. Specifically, the light receiving unit 4 is disposed at the center of the light receiving unit 4, that is, on the axis of the support cylinder 19 when projected in the vertical direction. ing. In addition, the light receiving unit 4 is disposed above the light emitting unit 2, and the lower surface is disposed to be a light receiving surface that receives reflected light 8 (described later).

  For example, a near-infrared camera, a CCD camera, or the like is used as the light receiving unit 4. Preferably, a CCD camera is used from the viewpoint of versatility.

  The upper surface of the support base 5 is formed as a smooth surface that can slide and support the lower surface of the suspension board with circuit 20.

  The inspection apparatus 1 is provided with a CPU (not shown). A CPU (not shown) is connected to the light receiving unit 4.

  Next, a method for inspecting the suspension board with circuit 20 for inspecting the quality of the foreign material 10 and the conductor pattern 23 in the insulating cover layer 24 in the suspension board with circuit 20 using the above-described inspection apparatus 1 will be described.

  As shown in FIGS. 2 and 3, the suspension board with circuit 20 used for the inspection is formed on a base-like insulating layer 22 and a base insulating layer 22 on a sheet-like metal support layer 21 extending in the longitudinal direction. The circuit board is obtained as a suspension board assembly sheet with circuit in which a plurality of conductive patterns 23 and a plurality of insulating cover layers 24 formed so as to cover the conductive patterns 23 are formed on the insulating base layer 22.

  That is, a plurality of suspension boards with circuit 20 are formed on the long metal support layer 21 along the longitudinal direction thereof.

  As a metal material for forming the metal support layer 21, for example, a metal material such as stainless steel, 42 alloy, aluminum, copper-beryllium, phosphor bronze, or the like is used. Preferably, stainless steel is used. The thickness of the metal support layer 21 is, for example, 15 to 50 μm, preferably 20 to 35 μm.

  As an insulating material for forming the base insulating layer 22, for example, a synthetic resin such as polyimide, polyamideimide, acrylic, polyether nitrile, polyether sulfone, polyethylene terephthalate (PET), polyethylene naphthalate, or polyvinyl chloride is used. Preferably, polyimide is used. The insulating base layer 22 has a thickness of, for example, 5 to 50 μm, or preferably 10 to 40 μm.

  As a conductive material for forming the conductive pattern 23, for example, a conductive material such as copper, nickel, gold, solder, or an alloy thereof is used. Preferably, copper is used.

  The conductor pattern 23 extends along the longitudinal direction (front-rear direction in FIG. 2), and wirings 25 arranged in parallel at intervals in the width direction (direction orthogonal to the longitudinal direction, left-right direction in FIG. 2), Terminal portions 27 arranged at both ends in the longitudinal direction of the wiring 25 are integrally provided.

  Each wiring 25 is covered with the insulating cover layer 24, while each terminal portion 27 is exposed from the insulating cover layer 24. The conductor pattern 23 is formed in a substantially rectangular shape in cross section (cross section in the width direction).

  The thickness of the conductor pattern 23 is, for example, 3 μm or more, preferably 5 μm or more, and is usually, for example, 30 μm or less, preferably 20 μm or less. When the thickness of the conductor pattern 23 is less than the above-described range, the formation of a raised portion 9 (described later) that reflects the incident light 7 may be insufficient.

  Moreover, the width | variety of each wiring 25 and each terminal part 27 is 5-500 micrometers, for example, Preferably, it is 15-200 micrometers, and the space | interval between each wiring 25 and the space | interval between each terminal part 27 are 5-200 micrometers, for example. The thickness is preferably 5 to 100 μm.

  The insulating cover layer 24 is formed on the upper surface of the insulating base layer 22 in a pattern that covers the wiring 25 and exposes the terminal portion 27.

  The insulating cover layer 24 is formed along the upper surface of the wiring 25 and both side surfaces in the width direction at portions corresponding to the wiring 25. As a result, a raised portion 9 is formed in the insulating cover layer 24 so as to rise upward corresponding to the cross-sectional shape of the wiring 25.

  Further, as the insulating material for forming the insulating cover layer 24, the same insulating material as that for forming the insulating base layer 22 described above is used, and polyimide is preferably used from the viewpoint of light reflection characteristics and the like. .

  The insulating cover layer 24 is formed by curing an uncured resin, for example.

  That is, first, for example, a resin solution containing a photosensitive resin such as a polyamic acid resin is applied on the base insulating layer 22 so as to cover the conductor pattern 23, and then dried to obtain a photosensitive layer. Form. Subsequently, the photosensitive layer is exposed and developed through a photomask, and then dried to form an uncured resin layer (not shown) made of an uncured resin such as a polyamic acid resin in the pattern described above. To do.

  Thereafter, the uncured resin layer is cured. For curing the uncured resin layer, for example, photocuring with an electron beam, ultraviolet light, or the like, for example, heat curing is used, and preferably heat curing is used. The heating temperature in heat curing is, for example, 300 to 500 ° C, preferably 360 to 440 ° C.

  Further, the transmittance T (transmittance for the cover insulating layer 24 having a thickness of 17 μm) with respect to light having a wavelength of 450 to 750 nm of the insulating cover layer 24 is, for example, 30% or less, preferably 15% or less, and is usually 0%. That's it. The transmittance T of the insulating cover layer 24 is measured with a spectrophotometer.

  Moreover, the reflectance (incident angle 0 degree) R with respect to the light of the wavelength 450-750 nm of the insulating cover layer 24 is 10-30%, for example, Preferably, it is 10-15%.

  The thickness of the insulating cover layer 24, that is, the portion covering the wiring 25, is the length from the surface (upper surface and side surface) of the wiring 25 to the surface (upper surface and side surface) of the insulating cover layer 24, and is exposed from the wiring 25. In the portion covering the insulating base layer 22, the length from the surface (upper surface) of the insulating base layer 22 to the surface (upper surface) of the insulating cover layer 24 is, for example, 50 μm or less, preferably 20 μm or less. 1 μm or more, preferably 3 μm or more. When the thickness of the insulating cover layer 24 exceeds the above range, the formation of the raised portions 9 may be insufficient.

  As shown in FIG. 1, the inspection using the inspection apparatus 1 is performed by conveying a long suspension board with circuit 20 using a conveyance apparatus 15. The transport device 15 includes, for example, an unwinding roll 16 and a winding roll 17 that are arranged at intervals in the front-rear direction. The inspection device 1 is disposed between the unwinding roll 16 and the winding roll 17 in the front-rear direction. In the transport device 15, a long metal support layer 21 is wound around the unwinding roll 16 in a roll shape, and the metal support layer 21 is roll-transported so that the winding roll 17 winds up. And in the middle of this roll conveyance, inspection is carried out.

  Specifically, the suspension board with circuit 20 in the middle of the roll conveyance is placed opposite to the support 5 and the inspection using the inspection apparatus 1 is performed, and then the suspension board with circuit 20 after the inspection is carried out by roll conveyance. While sending it out from the support stand 5 toward the winding roll 17, the suspension board with circuit 20 before the inspection is sent out from the take-up roll 16 to the support stand 5 so as to face it. Thereafter, the above operation is repeated.

  In this inspection, as shown in FIGS. 1 and 3, in the inspection apparatus 1, incident light 7 emitted by the light emitting unit 2 is incident on the surface of the insulating cover layer 24 in the suspension board with circuit 20.

  That is, as shown in FIG. 2, the incident light 7 is emitted from the obliquely upper side of the suspension board with circuit 20 toward the upper surface of the suspension board with circuit 20.

  Specifically, as shown in FIG. 1 and FIG. 3, the light emitting unit 2 transmits the incident light 7 from the light source 3 to its optical axis (incident optical axis) 13 and a horizontal plane (that is, the upper surface of the support base 5, That is, the angle α formed with the upper surface of the base insulating layer 22 is substantially 30 degrees or less, preferably 20 degrees or less, more preferably 10 degrees or less, and usually exceeds 0 degrees. So that it emits light.

  Further, when the incident light 7 has directivity, the light emitting unit 2 is configured such that the incident light 7 emitted from each light source 3 travels in parallel in a cross-sectional view along the vertical direction, and the support cylinder 19. The light is emitted so as to be incident on the suspension board with circuit 20 with a width corresponding to the vertical width (length).

  Next, the incident light 7 is reflected on the surface of the insulating cover layer 24 to become reflected light 8, and the reflected light 8 is detected by the light receiving unit 4.

  Specifically, the surface of the raised portion 9 of the insulating cover layer 24 formed corresponding to the wiring 25 is an upper portion (upper central portion) 32 that covers the upper surface of the wiring 25 (not including an upper peripheral end described later). And an end surface of a shoulder portion (peripheral end portion) 31 covering the upper peripheral end of the wiring 25, and reflected light 8 on the end surface of the shoulder portion 31 is mainly received by the light receiving portion 4.

  Specifically, the end surface of the shoulder portion 31 is formed in a curved shape (or a bent shape), whereby the angle β formed between the end surface of the shoulder portion 31 and the optical axis 13 of the incident light 7 is different from the end surface of the shoulder portion 31. Since the angle β is substantially the same as the angle β formed with the vertical direction, the reflected light 8 is mainly directed upward in the vertical direction and received by the light receiving unit 4.

  On the other hand, since the upper surface of the upper central portion 32 is formed flat along the front-rear and left-right directions, the reflected light 8 is obliquely upward on the side, more specifically incident light on the upper surface of the upper central portion 32. 7 is reflected at the same incident angle α1 as the angle α1 formed by the optical axis 13 and the upper surface of the upper central portion 32. Therefore, the reflected light 8 is not substantially detected by the light receiving unit 4.

  Further, the portion other than the raised portion 9 in the insulating cover layer 24 is formed as a flat portion 30 that is flat along the front-rear and left-right directions, and the reflected light 8 is obliquely laterally reflected on the surface of the flat portion 30. More specifically, the light is reflected at the same incident angle α2 as the angle α2 formed by the optical axis 13 of the incident light 7 and the surface of the flat portion 30. Therefore, the reflected light 8 is not substantially detected by the light receiving unit 4.

  Thereafter, the reflected light 8 received by the light receiving unit 4 is subjected to data processing by a CPU (not shown) to form an image processing diagram (see FIG. 5) of the outer shape of the wiring 25. Appearance of

  That is, as shown by a solid line in FIG. 4, when the short-circuit portion 11 is formed in the wiring 25, the upper central portion 32 of the raised portion 9 of the cover insulating layer 24 formed due to the short-circuit portion 11. Since the reflected light 8 reflected on the upper surface is mainly reflected toward the upper side obliquely, it is difficult for the light receiving unit 4 to receive the light. Therefore, the external shape data formed by the CPU is reflected at the end face of the shoulder portion 31 of the raised portion 9 of the cover insulating layer 24 formed due to the two wirings 25 that are originally arranged at intervals. The outline data is not received by the light 8. As a result, it is determined that the short-circuit portion 11 exists, the outer shape of the wiring 25 is abnormal, and the suspension board with circuit 20 is defective.

  On the other hand, as shown in FIG. 3, when the short circuit portion 11 is not formed in the wiring 25, the raised portion of the insulating cover layer 24 formed due to the two wirings 25 arranged at a distance from each other. Since the reflected light 8 reflected on the end face of the shoulder portion 31 of 9 is mainly reflected upward in the vertical direction, it is easily received by the light receiving unit 4. Therefore, the external shape data formed by the CPU is reflected at the end face of the shoulder portion 31 of the raised portion 9 of the cover insulating layer 24 formed due to the two wirings 25 that are originally arranged at intervals. It becomes the outer shape data that received the light 8. As a result, it is determined that the short-circuit portion 11 does not exist, the outer shape of the wiring 25 is normal, and the suspension board with circuit 20 is a non-defective product.

  In addition, as shown by a broken line in FIG. 4, when the defective portion 12 is formed in the wiring 25, it is reflected on the surface of the flat portion 30 of the cover insulating layer 24 formed due to the defective portion 12. Since the reflected light 8 is mainly reflected toward the side obliquely upper side, it is difficult for the light receiving unit 4 to receive the light. Therefore, the outline data formed by the CPU does not receive the reflected light 8 reflected from the end face of the shoulder portion 31 of the raised portion 9 of the insulating cover layer 24 formed due to the wiring 25 originally arranged. It becomes data. As a result, it is determined that the defective portion 12 exists, the outer shape of the wiring 25 is abnormal, and the suspension board with circuit 20 is defective.

  On the other hand, as shown in FIG. 3, when the defective portion 12 is not formed in the wiring 25, it is reflected on the end surface of the shoulder portion 31 of the raised portion 9 of the cover insulating layer 24 formed due to the wiring 25. Since the reflected light 8 is mainly reflected upward in the vertical direction, it is easily received by the light receiving unit 4. Therefore, the outer shape data formed by the CPU is the outer shape data obtained by receiving the reflected light 8 reflected from the end surface of the shoulder portion 31 of the raised portion 9 of the insulating cover layer 24 formed due to the wiring 25 originally arranged. Become. As a result, it is determined that the defective portion 12 does not exist, the outer shape of the wiring 25 is normal, and the suspension board with circuit 20 is a good product.

  Further, as shown in FIG. 4, when the foreign material 10 exists in the insulating cover layer 24, the end surface of the shoulder portion 31 of the raised portion 9 of the insulating cover layer 24 formed due to the foreign material 10 is used. The reflected light 8 that is reflected is mainly reflected upward in the vertical direction, so that it is easily received by the light receiving unit 4. Therefore, the outer shape data formed by the CPU is the outer shape data obtained by receiving the reflected light 8 reflected on the end surface of the shoulder portion 31 of the raised portion 9 of the insulating cover layer 24 formed due to the foreign substance 10 which does not exist originally. Become. As a result, it is determined that the foreign substance 10 exists and the suspension board with circuit 20 is defective.

  On the other hand, as shown in FIG. 3, when the foreign material 10 is not present in the insulating cover layer 24, the reflected light 8 reflected on the surface of the flat portion 30 of the insulating cover layer 24 is mainly lateral. Since the light is reflected obliquely upward, it is difficult for the light receiving unit 4 to receive the light. Therefore, in this case, the external shape data formed by the CPU is the reflected light 8 reflected on the end surface of the shoulder portion 31 of the raised portion 9 of the insulating cover layer 24 formed due to the non-existing foreign material 10. The outline data is not received. As a result, the foreign object 10 does not exist, and it is determined that the suspension board with circuit 20 is a non-defective product.

  As shown in FIG. 4, the foreign material 10 is embedded in the insulating cover layer 24, that is, the foreign material whose upper and lower surfaces are covered with the insulating cover layer 24, and further, although not shown, is formed on the upper surface of the insulating base layer 22. In other words, the lower surface includes a foreign substance that is in contact with the insulating base layer 22 and the upper surface is covered with the insulating cover layer 24.

  Examples of the material of the foreign material 10 include a material that impairs the function of the conductor pattern 23 (function of transmitting an electrical signal in the wiring 25) and / or the function of the cover insulating layer 24 (sealing function for the wiring 25), Specifically, it is a conductor material, an insulating material, etc., and examples of the conductor material include metal materials such as copper, tin, and stainless steel, and examples of the insulating material include polyethylene terephthalate (PET) and polystyrene (PS). ), Polypropylene (PP), air (void) and the like.

  The maximum length of the foreign material 10 is, for example, 5 to 100 μm.

  In this inspection apparatus 1, the incident light 7 is separated from the cover insulating layer 24 by the light emitting unit 2 so that the angle α formed between the optical axis 13 of the light source 3 and the upper surface of the base insulating layer 22 is a low angle within a specific range. The reflected light 8 reflected from the end surface of the shoulder 31 of the raised portion 9 of the insulating cover layer 24 formed due to the presence of the foreign material 10 and the quality of the wiring 25 is received by the light receiving unit 4. Is done. On the other hand, the reflected light 8 reflected on the upper surface of the upper portion 32 of the raised portion 9 and the surface of the flat portion 30 is less likely to be received by the light receiving unit 4.

  Therefore, the reflected light 8 received by the light receiving unit 4 can form a contrast corresponding to the foreign material 10, and the presence / absence of the foreign material 10 and the quality of the wiring 25 can be inspected at the same time with high accuracy.

  In the above description, the inspection apparatus 1 is described as an AVI apparatus for inspecting both the presence / absence of the foreign matter 10 in the insulating cover layer 24 and the quality of the conductor pattern 23. It can also be used as an AVI apparatus that inspects only the presence or absence of the foreign matter 10 inside.

  Moreover, since the fluorescent lamp described in Patent Document 1 causes diffused light to enter the coverlay layer in a diffuse manner, the amount of incident light in the coverlay layer is small, and the diffused light is incident only from a specific direction. The amount of incident light is significantly reduced. For this reason, the amount of reflected light received by the light receiving unit is also significantly reduced, so that the above-described inspection cannot be performed with high accuracy.

  However, in the inspection apparatus 1 described above, since the incident light 7 can be incident in a condensed manner from the light sources 3 arranged in a ring shape, the incident light 7 is reflected on the surface of the cover insulating layer 24 with a sufficient amount of light. Then, the reflected light 8 can be received by the light receiving unit 4 with a sufficient amount of light.

  Therefore, the above-described inspection can be performed with higher accuracy.

  Further, when the incident light 7 has directivity, the reflected light 8 received by the light receiving unit 4 can surely form a contrast corresponding to the foreign matter, and as a result, the presence or absence of the foreign matter 10 can be accurately determined. Can be inspected.

  In the above description, the inspection apparatus of the present invention is used for the inspection of the suspension board with circuit 20. For example, although not illustrated, a flexible printed circuit board or the like provided with a metal support layer 21 as a reinforcing layer as necessary. It can be widely applied to inspection of various printed circuit boards.

  In the above description of FIG. 1, the long suspension board with circuit 20 is inspected while being wound by the transport device 15 including the unwinding roll 16 and the winding roll 17. One (single-sheet) suspension board assembly sheet with circuit can also be inspected without using the roll 16 and the winding roll 17.

  In the description of the conductor pattern 23 described above, the wirings 25 are arranged in parallel at intervals in the width direction. However, the parallel direction of the wirings 25 is not particularly limited. For example, the wirings 25 are arranged at intervals in the longitudinal direction. It can also be arranged in parallel.

  In the description of FIG. 4 described above, the foreign material 10 is shown as being mixed between the wirings 25. For example, although not shown, even if the foreign material 10 is mixed outside the parallel wirings 25, The presence or absence can be checked.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the examples and comparative examples.

Example 1
(Aspect where the angle between the optical axis of the light source and the upper surface of the base insulating layer is 25 degrees)
A ring illumination including the above-described members (a light-emitting unit including a support cylinder and a plurality of LEDs, a light-receiving unit including a CCD camera, and a support base) are formed. An inspection device (AVI) was prepared.

  In this inspection apparatus, incident light having a wavelength of 620 nm is emitted from the light emitting unit at an angle (α) formed by the optical axis of the light source and the upper surface of the support base (parallel to the upper surface of a base insulating layer described later) at 25 degrees. Arranged.

  As a suspension board with circuit to be used for inspection, on a long metal support layer made of stainless steel foil having a thickness of 20 μm, a base insulating layer made of polyimide having a thickness of 10 μm, a conductor pattern made of copper having a thickness of 12 μm, and What prepared the cover insulating layer which consists of a 17-micrometer-thick polyimide obtained by heat-curing the uncured resin layer which consists of uncured polyamic acid resin was prepared.

  Further, a foreign substance having a thickness of about 15 μm, a width of about 15 μm, and a length of 15 μm was mixed in the insulating cover layer.

  The cover insulating layer (thickness: 17 μm) had a transmittance (T) for light with a wavelength of 620 nm of 12% and a reflectance (incident angle of 0 °) (R) for light with a wavelength of 620 nm was 10%. The transmittance (T) was measured with a spectrophotometer (V-670, an ultraviolet-visible near-infrared spectrophotometer, manufactured by JASCO Corporation).

  Then, incident light is incident on the insulating cover layer by the light receiving portion of the inspection apparatus, reflected light reflected by the light receiving portion is received by the light receiving portion, and an image processing diagram showing the raised portion of the insulating cover layer is obtained by the CPU. . The obtained image processing diagram is shown in FIG.

Comparative Example 1
(Aspect where the angle between the optical axis of the light source and the upper surface of the base insulating layer is 60 degrees)
The cover insulating layer is raised in the same manner as in Example 1 except that the light emitting portion of the inspection apparatus is arranged so that the angle (α) formed by the optical axis of the light source and the upper surface of the support base is emitted at 60 degrees. An image processing diagram showing the part was obtained. The obtained image processing diagram is shown in FIG.

Comparative Example 2
(Aspect where the angle between the optical axis of the light source and the upper surface of the base insulating layer is 50 degrees)
The cover insulating layer is raised in the same manner as in Example 1 except that the light emitting portion of the inspection apparatus is arranged so that the angle (α) between the optical axis of the light source and the upper surface of the support base is emitted at 50 degrees. An image processing diagram showing the part was obtained. The obtained image processing diagram is shown in FIG.

(Evaluation)
In the image processing diagrams of FIGS. 5 to 7 obtained in Example 1 and Comparative Examples 1 and 2, the foreign matters in the insulating cover layer and the outer shape of the wiring were observed and evaluated according to the following criteria. The results are shown in Table 1.

    ○: Foreign matter was observed and the image of the outer shape of the wiring was clear.

    X: No foreign matter was observed, and the image of the outer shape of the wiring was blurred, unclear or slightly unclear.

DESCRIPTION OF SYMBOLS 1 Inspection apparatus 2 Light emission part 3 Light source 4 Light reception part 7 Incident light 8 Reflected light 10 Foreign material 13 Optical axis (incident optical axis)
20 Suspension board with circuit 22 Base insulating layer 23 Conductor pattern 24 Cover insulating layer α Angle formed by the light source of incident light and the upper surface of the base insulating layer

Claims (6)

The cover in a printed circuit board comprising a base insulating layer, a conductor pattern formed on the base insulating layer, and a cover insulating layer formed on the base insulating layer so as to cover the conductor pattern An inspection device for inspecting the presence or absence of foreign matter in the insulating layer and the quality of the conductor pattern ,
A light emitting unit that emits incident light incident on the insulating cover layer;
A light receiving portion that is disposed above the printed circuit board and that receives the reflected light reflected by the surface of the insulating cover layer.
A plurality of light sources of the light emitting unit are arranged in an annular shape,
The inspection apparatus, wherein the light emitting unit emits the incident light so that an angle formed between an optical axis of the light emitting unit and an upper surface of the base insulating layer is 30 degrees or less. The inspection apparatus according to claim 1 , wherein the incident light has directivity. The inspection apparatus according to claim 1 , wherein the inspection apparatus is used for inspecting the presence or absence of a foreign substance in the insulating cover layer in the printed circuit board including the insulating cover layer having a thickness of 50 μm or less. The thickness of the wired circuit board comprising the 3μm or more of the conductor pattern, characterized in that it is used to test the quality of the conductor pattern inspection apparatus according to claim 1. Wherein the wavelength of the incident light, characterized in that it is a 450 to 750 nm, inspecting apparatus according to claim 1. Using the inspection apparatus according to claim 1, characterized by checking the presence or absence of the foreign substance of the insulating cover layer in the wiring circuit board, the wiring circuit inspection method of a substrate.