JP2003332730A - Device and method for inspecting solder for appearance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for inspecting solder for appearance that can improve a function of identifying the applied state of solder applied to an electrode further enhancing the contrast between the electrode and solder. <P>SOLUTION: This device for inspecting solder for appearance is provided with a light source 3 which projects light containing ultraviolet rays upon an object to be inspected including the electrode 9 containing copper of gold in its external surface as the main component and the solder 10 applied to the electrode 9, a camera 4 which picks up the images of the electrode 9 and solder 10 in an ultraviolet region with the light reflected on the object by receiving it, and a discriminating section 5 which discriminates the applied state of the solder 10 from the images picked up by means of the camera 4. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solder visual inspection apparatus and a solder visual inspection method for inspecting a coating state of solder applied to electrodes on a substrate by printing or the like.

[0002]

2. Description of the Related Art As a solder visual inspection apparatus of this type, as disclosed in Japanese Patent Application Laid-Open No. 5-296746,
What determines the size and shape of the solder applied to the surface of the electrode containing copper or gold as the main component, the position of the solder with respect to the electrode, etc., and the state of the solder applied, and judge from the obtained image. Are known. In the case of this device, a halogen lamp provided with a condenser lens and a blue filter is used as a light source for illumination required for imaging. The light from the light source is applied to the solder and the electrodes obliquely from above, and the reflected light is imaged by the imaging camera. This imaging was performed in the visible light region.

[0003]

In this conventional solder visual inspection apparatus, a light source capable of radiating all wavelengths of visible light is imaged by a camera with a blue filter interposed, whereby the sensitivity region of the imaged light is reduced. 450n at peak wavelength of light
It is set to fall within the range of m to 550 nm. The spectral reflectance from the electrode containing copper or gold as a main component in this wavelength region is not constant. For example, 550n
In the wavelength range of m, the reflectance from copper is about 70%, the reflectance from gold is about 80%, and the reflectance from solder is 90%. Therefore, the amount of light reflected from copper or gold is less than the amount of light reflected from solder, but since there is not much difference in the amount of light, it is difficult to clearly identify the boundary between the electrode portion and the solder portion, and highly accurate inspection is possible. Cannot be done.

The present invention provides a solder visual inspection apparatus capable of enhancing the function of discriminating the applied state of solder by further enhancing the contrast between the applied state of the solder applied to the electrode and the solder. It is a problem to be solved to provide a solder visual inspection method.

[0005]

In a solder visual inspection apparatus according to the present invention, an electrode having a metal material on the outer surface thereof, which has a reflectance of 50% or less of a predetermined irradiated ultraviolet light, is applied to the electrode. A light source that irradiates an inspection target including solder with light including ultraviolet light; a camera that inputs reflected light from the inspection target to image or photograph the electrode and the solder in an ultraviolet light region; And a determination unit that determines the coating state of the solder based on the image acquired in (1).

Here, the light source may be one that emits only ultraviolet light, or light that includes light in the ultraviolet light region and light in other wavelength regions. The light source emits light containing at least light in the ultraviolet region.

[0007] Further, to image or photograph in the ultraviolet region means to photograph or photograph in the ultraviolet region with a camera having an imaging or photographing sensitivity in the ultraviolet region. This camera is not limited to the CCD solid-state image pickup camera, and may be a camera for taking an image on a film, or the like, as long as it has the above-mentioned image taking or taking function.

Further, the judging section judges whether the solder coating state is good or not.

If desired, the surface of the metal material of the present invention may be coated with a light-transmissive coating.

According to the present invention, of the irradiated light, the spectral reflection efficiency of light in the ultraviolet region is as high as 90% for solder, whereas it is as low as 50% or less for electrodes. Based on the acquired image, it is determined that the boundary between the solder and the electrode is clear. Therefore, the size and shape of the solder and the positional relationship with the electrode can be clearly determined, and the quality of the solder coating state can be determined with high accuracy based on the determination.

The present invention is preferably characterized in that the metal material contains copper or gold as a main component.

Here, the main component referred to in the present invention refers to a material having the highest contained ratio.

According to the present invention, of the irradiated light, the spectral reflection efficiency of light in the ultraviolet region is as high as 90% for solder, whereas it is as low as 50% or less for copper or gold. Based on the image captured by the camera, the solder is determined to have a clear boundary with the electrode having the outer surface made of copper or gold. Therefore, the size and shape of the solder and the positional relationship with the electrode can be clearly determined, and the quality of the solder coating state can be determined with high accuracy based on the determination.

In the solder visual inspection apparatus according to the present invention, preferably, the light source uses an ultraviolet light emitting diode. In this case, the emission of ultraviolet light is strong, and the assembly as a light source is easy to handle.

In the solder visual inspection apparatus according to the present invention, it is preferable that the image pickup or photographing by the camera has a wavelength of 30.
It is performed in the near-ultraviolet light region of 0 nm to 420 nm.

In the solder visual inspection apparatus according to the present invention, preferably, the electrode is an electrode made of copper, an electrode made of copper whose surface is plated with gold, an electrode made of gold, and the surface of which is plated with copper or gold. Any one of the electrodes selected from the other electrodes.

In the solder appearance method according to the present invention, an electrode having an outer surface made of a metal material having a reflectance of 50% or less of a predetermined irradiated ultraviolet light and a solder applied to the electrode are inspected. , An irradiation step of irradiating the inspection target with light including ultraviolet light, an image acquisition step of capturing or photographing the inspection target with a camera in the irradiation state, and the image acquisition step based on the image obtained in the image acquisition step. And a determination step of determining the appearance of the solder.

According to the solder appearance inspection method of the present invention, the size and shape of the solder and the positional relationship with the electrodes can be clearly determined,
Based on the determination, the quality of the solder coating state can be determined with high accuracy.

The solder visual inspection method according to the present invention is preferably characterized in that the metal material contains copper or gold as a main component.

According to the solder visual inspection method of the present invention, the size and shape of the solder and the positional relationship with the electrodes can be clearly determined,
Based on the determination, the quality of the solder coating state can be determined with high accuracy.

[0021]

DETAILED DESCRIPTION OF THE INVENTION The details of the present invention will be described below with reference to the embodiments shown in the drawings.

1 to 3 show a solder visual inspection apparatus according to an embodiment of the present invention. FIG. 1 is a schematic explanatory view of a solder appearance inspection apparatus, FIGS. 2 and 3 show an example of an image of an inspection object taken by a camera, and FIG. 2 shows an image taken by a camera having sensitivity in a visible light region. Reference numeral 3 represents an image captured by a camera having sensitivity in the ultraviolet light region.

With reference to these figures, the solder visual inspection apparatus 1 includes a board setting portion 2, an illumination light source 3, and a camera 4.
And a quality determination unit 5 as a determination unit, and an imaging control unit 6.

The board setting section 2 holds the board 7 on which the solder visual inspection is performed, and the movement thereof can be controlled by the image pickup control section 6 in two-dimensional directions such as left, right, front and rear. By the movement control of the substrate placement unit 2, the substrate 7 is also controlled to be movable, and thus the inspection target on the upper surface of the substrate 7 is
The position is appropriately changed and adjusted to a position suitable for imaging by the camera 4.

On the surface of the substrate 7, electrodes 9 and wiring patterns (not shown) are formed of copper foil, respectively.
Further, the solder resist 11 is applied to the portion excluding the electrodes 9. Cream solder is applied to the electrode 9 by printing.

The illumination light source 3 is a light source for illuminating the surface of the substrate 7, and the substrate 7 held by the substrate installation portion 2
Is disposed immediately above and is supported by a support mechanism (not shown). The illumination light source 3 is configured by arranging a plurality of, for example, eight ultraviolet light emitting diodes (LEDs) 8 in an annular shape in plan view, and has a through hole in the center. This ultraviolet light emitting diode emits ultraviolet light. The size of the annular structure of the illumination light source 3, that is, the arrangement of the ultraviolet light emitting diodes is such that the light from each ultraviolet light emitting diode 8 illuminates the upper surface of the substrate 7 at an angle of about 30 degrees. It is set.

The camera 4 is arranged above the center of the through hole of the illumination light source 3. By the arrangement setting of the respective ultraviolet light emitting diodes 8, the irradiation light to the solder resist 11 is almost totally reflected, whereas the irradiation light to the solder 10 and the electrode 9 is diffusely reflected on the surface thereof. It Therefore, the reflected light from the solder resist 11 does not enter the camera 4, whereas the reflected light from the solder 10 and the electrode 9 enters the camera 4. In FIG. 1, an example of the irradiation light and its reflected light is shown by a chain line.

The camera 4 has a sensitivity C in the near ultraviolet region.
It is composed of a CD solid-state imaging camera. The photosensitivity region of the camera 4 is a wavelength region included in the near ultraviolet region of 300 nm to 420 nm. Therefore, the camera 4 can only take an image of light in the near ultraviolet region. The light source for the image pickup is also set to emit light having a wavelength corresponding to the sensitivity region of the near-ultraviolet light by each ultraviolet light emitting diode 8, so that the image obtained by the image pickup is clear. , With high contrast.

That is, referring to FIG. 4, for example, 400
The reflectance of copper or gold in ultraviolet light having a wavelength of nm is 50% or less, while the reflectance of solder is approximately 90%, so that the imaging sensitivity of the camera 4 at 400 nm is
Solder is about twice as good as copper or gold. FIG. 4 is a graph showing the spectral reflectance at each wavelength when white light is irradiated on copper, gold, and solder, where the horizontal axis indicates the wavelength of the reflected light and the vertical axis indicates the spectral reflectance. In FIG. 4, copper is shown by a broken line, gold is shown by a one-dot chain line, and solder is shown by a solid line. Therefore, the contrast ratio between the imaged electrode and the solder is higher than the image taken when the reflectance of copper or gold is close to 80% as in the conventional case where the image is taken in the visible blue light region. Becomes larger, and the solder shape etc. can be clearly identified. Therefore, the quality of the solder such as the size and shape of the solder and the position with respect to the electrode can be accurately determined. The comparative example is shown in FIG. Figure 2
The solder 10 and the electrodes 9 when the image is picked up in the blue region of visible light are shown. In this case, the solder resist 11 on the substrate 7
The portions are dark as shown by hatching, and the electrode 9 and solder 10 portions are equally bright as shown by white. Therefore, it is difficult to distinguish the electrode 9 from the solder 10, and the shape of the solder 10 cannot be accurately identified. On the other hand, the captured image when the image is captured in the ultraviolet region is illustrated in FIG. In this case, the solder resist 11 on the substrate 7
The portion is darkest as shown by hatching, the electrode 9 portion is darkest as shown by cross hatching, and the solder 10 portion is brightest as shown by outline. Therefore, the shape and the like of the solder 10 portion with respect to the electrode 9 are clearly identified, and the quality of the solder 10 is satisfactorily determined.

The solder appearance inspection method will be described in detail.

First, the substrate 7 is set on the substrate setting section 2. The illumination light source 3 is a substrate 7 installed on the substrate installation unit 2.
It is installed at a predetermined height position just above. The camera 4 is installed above the illumination light source 3.

After this installation, the illumination light source 3 is used for imaging.
Is activated. By this operation, 3 is applied to the surface of the substrate 7.
Ultraviolet light with a wavelength of 00 nm to 420 nm is emitted from a predetermined oblique angle (in this case, 30 degrees with respect to the substrate surface).
This ultraviolet light is reflected by the surface of the substrate 7. The reflected light includes reflected light from the solder resist 11, reflected light from the electrode 9, and reflected light from the solder 10. Since the reflected light from the solder resist 11 is almost totally reflected on the surface of the solder resist 11, it hardly enters the camera 4.

On the other hand, since the reflected light from the surface of the electrode 9 and the reflected light from the solder 11 are both diffusely reflected, the reflected light directed upward is incident on the camera 4.
The camera 4 takes an image in a state in which it has sensitivity only to ultraviolet light of the incident light. The image information obtained by this imaging is input to the quality determination unit 5, and the quality determination unit 5 determines the quality of the applied state of the solder 10.
The quality determination unit 5 reads the size and shape of the solder 10 and the positional deviation state with respect to the electrode 9 from the image information, and determines the quality based on the determination conditions provided in advance.

The present invention is not limited to the above embodiment, and the following modifications and applications may be made.

(1) The camera is not limited to the one that captures an image by converting light into an electric signal, and may be a camera that captures an image by capturing an image on a film or the like. In this case, a member, such as a film, that captures an image has a photographing sensitivity in the ultraviolet region.

(2) The inspection object is illuminated with light from a light source capable of irradiating white light including ultraviolet light, and the reflected light from the inspection object at that time is detected by a camera having sensitivity in the ultraviolet light region. It may be configured such that an image is taken or photographed, and the solder application state is determined based on the image obtained by the image pickup or image pickup.

(3) An ultraviolet filter capable of illuminating an object to be inspected with light from a light source capable of irradiating white light including ultraviolet light and allowing the reflected light from the object to be inspected at that time to pass only ultraviolet light. It is also possible to use a camera having a sensitivity to light including an ultraviolet light region to capture or photograph, and to determine the solder coating state based on the image obtained by the photographing or photographing. .

(4) The irradiation angle of the light from the light source to the substrate is
It may be set in the range of about 20 to 30 degrees with respect to the substrate surface.

(5) FIG. 5 shows a modification of the solder visual inspection apparatus. The solder visual inspection apparatus 1 includes a board installation unit 2, an illumination light source 3, a quality determination unit 5, and an image pickup control unit 6, similarly to the solder visual inspection device shown in FIG. The camera 4 is configured such that the upward reflected light from the substrate 7 is once reflected by the reflecting member 12 formed of a mirror or prism so as to change its direction to the lateral direction, and is imaged by the camera 4 arranged laterally. is doing. in this case,
Although one reflection member 12 is provided, a plurality of reflection members 12 may be combined to guide the reflected light from the substrate 7 to the camera 4.

(6) The electrode may be any one electrode selected from an electrode made of copper having a surface plated with gold, an electrode made of gold, and an electrode having a surface plated with copper or gold.

(7) An ultraviolet lamp may be used as the light source.

(8) When the visual inspection is performed by the solder visual inspection device, the surface of the metallic material to be inspected may be coated with a coating material capable of transmitting light. In that case, the coating material may be applied together with the solder, and the coating material may be applied only to a metal material having an ultraviolet reflectance of 50% or less.

[0043]

According to the present invention, of the irradiated light,
The spectral reflection efficiency of light in the ultraviolet region is as high as 90% for solder, whereas it is less than 50% for copper or gold. Therefore, based on the image captured by the camera or captured by the camera, The solder is judged to have a clear boundary with an electrode having an outer surface made of copper or gold. Therefore, the size and shape of the solder and the positional relationship with the electrode can be clearly determined, and based on the determination, the quality of the solder coating state can be accurately determined.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a solder visual inspection device according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing an example of an image captured by a camera having a sensitivity in a visible light region of reflected light of each of a substrate, an electrode, and solder that is inspected by the solder visual inspection apparatus of FIG.

FIG. 3 is a conceptual diagram showing an example of an image captured by a camera having a sensitivity in an ultraviolet light region in reflected light of each of a substrate, an electrode, and solder which is inspected by the solder visual inspection apparatus of FIG.

FIG. 4 is a graph showing spectral reflectance at each wavelength when white light is irradiated on copper, gold, and solder.

FIG. 5 is a schematic explanatory view showing a modified example of the solder visual inspection apparatus of the present invention.

[Explanation of symbols]

1 Solder appearance inspection device 3 light sources 4 cameras 5 Pass / fail judgment unit (judgment unit) 8 Ultraviolet light emitting diode 9 electrodes 10 Solder

Claims (7)

[Claims] 1. The reflectance of a predetermined ultraviolet light irradiated is 50.
% Light source for irradiating light including ultraviolet light to an inspection target including an electrode having an outer surface of a metal material and solder applied to the electrode, and a reflected light from the inspection target. A camera for imaging or photographing the electrode and the solder in the ultraviolet region, and a determination unit for determining the coating state of the solder based on the image acquired by the camera, the solder characterized by the following: Appearance inspection device. 2. The solder visual inspection apparatus according to claim 1, wherein the metal material contains copper or gold as a main component. 3. The solder visual inspection apparatus according to claim 1, wherein the light source is a light emitting diode for ultraviolet light. 4. The solder visual inspection apparatus according to claim 1, wherein the image pickup or photographing by the camera has a wavelength of 300 nm.
To 420 nm near-ultraviolet light region. 5. The solder visual inspection apparatus according to claim 1, wherein the electrode is an electrode made of copper, an electrode made of copper whose surface is plated with gold, an electrode made of gold, and A solder visual inspection apparatus, wherein the electrode is one electrode selected from electrodes plated with copper or gold. 6. The reflectance of the irradiated predetermined ultraviolet light is 50.
% Of the electrode having a metal material on the outer surface and the solder applied to the electrode as an inspection target, and an irradiation step of irradiating the inspection target with light including ultraviolet light; and the inspection target in the irradiation state. A method for inspecting solder appearance, comprising: an image acquisition step of capturing or shooting the image with a camera; and a determination step of determining the appearance of the solder based on the image obtained in the image acquisition step. 7. The solder visual inspection method according to claim 6, wherein the metal material contains copper or gold as a main component.