JP4228773B2 - Board inspection equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is, for example, IC (Integrated Circuit) suitably applied to a component inspection of printed circuit board mounted in the chip or the like, relates to a substrate inspection equipment.
[0002]
[Prior art]
Conventionally, an X-ray board inspection apparatus using X-rays is used for the purpose of, for example, inspection of the solder state inside a BGA (Ball Grid Array) of an IC package used for high-density board mounting. The inspection of the mounting substrate is not completed by itself, and the component polarity, positional deviation, and product type difference of the component chip to be mounted are performed by an optical substrate inspection device based on an optical image using visible light (for example, see Patent Document 1). .)
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-295242
[Problems to be solved by the invention]
However, when all of the solder fillets that are difficult to see in the optical image are viewed with X-rays, there is a problem that there is a case where parts cannot be distinguished from solder and some cannot be inspected. Further, if the optical substrate inspection device and the X-ray substrate inspection device are arranged in a series of two units, it is very disadvantageous in terms of cost and space.
[0005]
In view of such points, the present invention, when performing board inspection using, for example, an X-ray image, examines X-ray images and optical images, such as components that cannot be distinguished from solder and components by X-ray images. depending an object and TURMERIC row optimal inspection by inspection in combination.
[0006]
[Means for Solving the Problems]
Substrate inspection device of the present invention includes an X-ray imaging unit for imaging the transmitted X-ray image of the X-rays irradiated to the inspected object that implements parts products, and the visible light imaging section for imaging the object to be inspected the X-ray image obtained by X-ray imaging unit including solder the securing parts and the component, by combining a portion corresponding to the component of the optical image obtained by the visible light imaging unit, wherein Image processing means for generating a composite image in which a part equivalent part of the X-ray image is replaced with a part equivalent part of the optical image, and the X-ray image and the optical image according to the parts mounted on the inspection object Or a selection means for selecting an examination based on a composite image of the X-ray image and the optical image .
[0007]
Further, in the board inspection apparatus described above, the image processing means calculates the difference between the center of gravity position of the solder of the solder portion in the X-ray image and the center of gravity position of the high-luminance portion of the solder portion in the X-ray image. In addition, the shape of the solder is inspected based on the difference between the center of gravity position of the entire solder of the solder portion and the center of gravity of the high brightness portion of the solder portion.
[0008]
In the board inspection apparatus described above, the image processing means causes the distance between the center of gravity positions of the entire solder of the opposing solder portions in the X-ray image and the high brightness portion of the opposing solder portions in the X-ray image. Based on the difference between the distance between the center of gravity of the entire solder of the opposing solder part and the distance between the center of gravity of the high brightness part of the opposing solder parts, Inspecting the presence or absence of the parts [0009]
According to the present invention, the optical image and the X-ray image are combined and processed, and the processed composite image is used to determine, for example, the solder or the component that cannot be distinguished from the solder or the component in the X-ray image. Will be able to. Further, the selection means selects an optimal inspection based on an X-ray image, an optical image, a composite image, or a combination thereof, depending on the type of component mounted on the board.
[0010]
In the present invention, a luminance distribution over a wide range on the substrate can be obtained at a time by X-ray irradiation, and the quality of soldering can be determined based on the solder state calculated from the luminance distribution. In particular, it is preferable to inspect the shape of the corresponding solder based on the difference between the center of gravity position of the entire solder in the X-ray image and the position of the center of gravity of the high luminance portion of the solder portion. This difference becomes large with normal solder.
[0011]
Furthermore, in the present invention, based on the difference between the distance between the gravity center positions of the entire solder of the opposing solder portions in the X-ray image and the distance between the gravity center positions of the high-luminance portions of the opposing solder portions in the X-ray image. Thus, it is preferable to inspect the shape of the corresponding solder. In the case of normal solder, this difference is large because the center of gravity of the high-luminance portion of the solder portion is present outside the center of gravity of the entire solder.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of a substrate inspection apparatus of the present invention and a substrate inspection method applied to this example will be described with reference to FIGS.
[0015]
FIG. 1 is a schematic equipment configuration diagram of the substrate inspection apparatus of this example. Reference numeral 1 denotes a data collection device that collects image data of an inspection object and supplies it to a data processing device. An X-ray source 6 that emits X-rays is disposed below an inspection target substrate (hereinafter simply referred to as a substrate) 5 on which components such as an IC chip are mounted. An optical CCD camera 2 as an optical imaging unit and an X-ray receiving CCD camera 3 as an X-ray imaging unit are disposed above the inspection target substrate 5. The optical CCD camera 2 and the X-ray light receiving CCD camera 3 include, for example, a mechanism unit 4 and are moved or moved on a plane perpendicular to the paper surface automatically or by user operation. Alternatively, the substrate 5 may be placed on an XY stage (not shown) that can move on a plane perpendicular to the paper surface, and the substrate 5 may be positioned by moving the XY stage. Further, the X-ray source 6 may be provided with a mechanism portion so as to be movable.
[0016]
Since the device using X-rays is housed in a sealed case to prevent leaking radiation, the inside of the case is completely dark, so normal illumination is necessary as a means for obtaining visible light, but the description is omitted here. ing.
[0017]
Reference numeral 10 denotes a data processing device. Processing and processing of image data captured and transmitted by the data collection device 1, analysis of data, control of irradiation X-rays of the X-ray source 1 via a GUI as an operation means, Control of the mechanism unit 4 or the like, or control such as selecting an appropriate inspection method according to the type of component mounted on the substrate 5 is performed. Various types of data processing apparatus 10 such as a personal computer can be considered.
[0018]
Reference numeral 11 denotes a CPU for controlling and calculating the data collecting apparatus, 12 is a main memory including a ROM storing a control program of the CPU 11 and a RAM functioning as a work area, and 13 is an optical CCD camera 2 and an X-ray receiving CCD camera 3. An image board as image processing means for processing and processing transmitted image data, 14 is an I / O board for performing input / output necessary for the apparatus, and 15 is a motor board for controlling the positioning of the mechanism unit 4 and the like. . Reference numeral 16 denotes a GUI (Graphical User Interface) composed of display means such as an LCD and operation means such as a keyboard, mouse, or touch panel. These devices are connected by a system bus 17 to transmit and receive data. Note that the representation of wiring from each device of the data collection device 1 to each board of the data processing device 10 is omitted.
[0019]
In the substrate inspection apparatus configured as described above, when an X-ray image of the inspection target substrate 5 is obtained, the mechanism unit 4 is controlled so that the X-ray source 1, the inspection target substrate 5, and the X-ray receiving CCD camera 3 are in a straight line. Deploy. When the substrate 5 is irradiated with X-rays from the X-ray source 6, the X-rays are transmitted through the substrate 5, and the X-ray receiving CCD 3 provided above the substrate 5 images the transmitted X-rays. Then, the image data captured by the X-ray light receiving CCD camera 3 is transmitted to the image board 13 to perform image processing, and an X-ray image is displayed on the display screen of the GUI 16.
[0020]
On the other hand, when an optical image of the inspection target substrate 5 is obtained, the mechanism unit 4 is controlled so that the optical CCD camera 2 and the inspection target substrate 5 are in an appropriate positional relationship. Then, the substrate 5 is imaged by the optical CCD camera 2, image data captured by the optical CCD camera 2 is transmitted to the image board 13, image processing is performed, and an optical image is displayed on the display screen of the GUI 16.
[0021]
The image board 13 also functions as an image processing unit that synthesizes an X-ray image and an optical image, and uses an X-ray image and an optical image held in the main memory 12 or the like according to a command from the CPU 11 as necessary. Then, the composition process can be performed and the created composite image can be displayed on the display screen of the GUI 16.
[0022]
In the following, a soldering quality determination method based on a solder shape inspection will be described in order to inspect the soldering state of a chip component mounted on a substrate using the above-described board inspection apparatus.
[0023]
A solder shape inspection using an X-ray image of a chip component on a substrate, for example, a chip resistor will be described. FIG. 2 shows an example of an optical image obtained by imaging a part of the substrate on which the chip component is mounted. In the figure, there appear to be four parts, but there are chip parts on both sides and the chip part is missing in the center. FIG. 3 is an X-ray image obtained by imaging the same part as FIG. 2 with X-rays.
[0024]
FIG. 4 shows an X-ray image threshold display based on the X-ray image of FIG. The X-ray image threshold display represents the luminance distribution of the X-ray image shown in FIG. 2. Specifically, the 8-bit, 256-gradation luminance display is displayed by color-coding every 10 gradations. The portion with high luminance is a portion with low X-ray transmittance, that is, a solder portion, and is displayed in yellow or green in this example.
[0025]
For example, assuming that the portion where the solder is present is a color of pink or higher color, the position of the center of gravity (+ portion) 20a of the entire solder in the portion where the solder is present and the position of the center of gravity (+ portion) 20b of the high luminance portion above yellow The solder shape can be inspected by calculating the difference. For example, the center of gravity position can be calculated by calculating the area of the target portion from the luminance distribution and calculating the center thereof, for example, using a function of the image processing software engine. In addition, since the brightness distribution of the X-ray image shows the height of the cross section of the solder part beside the chip component and the degree of solder rise, the volume (solder amount) of the solder fillet can be calculated.
[0026]
A method of measuring the height of a solder part by irradiating the solder part with a laser beam and measuring the reflected laser beam is known, but this conventional method is based on a laser spot unit of a minimum area. It took time to measure the height of the. In the method using the luminance distribution of X-rays in this example, X-rays are irradiated on the entire substrate, and the solder height measurement processing of each component can be performed together, so that it is efficient and the measurement time is short. There are advantages.
[0027]
The distance between the center of gravity position 20a where the chip component solder of FIG. 4 is located and the opposite center of gravity position on this component is A, and the distance between the center of gravity position 20b of the high brightness portion and the opposite center of gravity position on this component is B. For example, it is possible to inspect the presence or absence of parts by measuring the distance between the highest points in each pad. For example, in the normal solder fillet a portion, the uppermost point 20b exists outside the image, but in the portion b where the chip floats or is missing, the uppermost point 20b exists in the center, that is, near the center of gravity 20a.
[0028]
FIG. 5A shows a schematic diagram of a solder fillet cross-section of the chip part in part a of FIG. 4. A state in which a normal solder fillet 22 is formed on the chip component 21 placed on the substrate 5 is shown. FIG. 5B shows a schematic diagram of a solder fillet cross section of the chip part of FIG. A state in which a solder fillet 23 with poor soldering is formed on the chip component 21 placed on the substrate 5 and the chip component 21 is floating is shown. As described above, whether soldering is good or bad is determined not only by the area and volume but also by the solder shape, so that more accurate determination can be made.
[0029]
FIG. 6 is a three-dimensional view (3D view) of a solder portion of a chip component. The height of the cross section of the solder part is detected from the difference in luminance of the X-ray image, and a three-dimensional view displayed in a mesh shape is created. The plan views shown in FIGS. Represent the shape visually. For example, in the case where it is difficult to inspect depending on the above-described plan view, a command is generated from the CPU 11 in response to an instruction from the user GUI 16 or automatically, and a three-dimensional diagram is created, and the user visually recognizes the solder shape. By using this three-dimensional view together when checking, the solder shape can be easily confirmed.
[0030]
Next, solder inspection based on a combination of an X-ray image and an optical image will be described using a chip capacitor as an example as a chip component. The same chip capacitor as the X-ray image and optical image of FIG. 7 is imaged. As can be seen from this X-ray image, in X-rays, there are components that are in a so-called blackened state, such as chip capacitors, and cannot be distinguished from solder and components. In such a case, the X-ray image cannot accurately inspect the solder portion. Therefore, by using the optical image, the X-ray image and the optical image are combined on the image board 13, and a processed image is created by cutting out a part equivalent part from the X-ray image, thereby knowing the exact position of the solder part. Can do. In the figure, an enclosure 20 represents a solder portion of the processed image.
[0031]
FIG. 8 shows the processed image shown in FIG. 7 processed to a level that can be used for actual inspection. In the figure, the enclosure portion 20 indicates a solder portion. 7 shows basic processing (easy to see and understand by humans), but in actual inspection, finally the image data is binarized and there are only two types of brightness levels, Hi and Lo. Do not let it. Therefore, the part of the component obtained by optics is erased from the luminance including the solder and the component detected by X-rays, and the processing is performed only for the X-ray solder.
In the formula
X-ray (component / solder)-optics (component) = X-ray (solder)
It is expressed.
[0032]
Next, a case where, for example, a BGA (Ball Grid Array) is inspected as a chip component will be described as an example. FIG. 9 shows an optical image of the BGA mounted on the substrate and its peripheral part. As inspection items here, check for misalignment, polarity, and product type. In the misregistration check, a so-called fiducial mark provided on the substrate as a reference position is detected and corrected. These checks are applied to various other components such as tantalum capacitors, electrolytic capacitors, various ICs such as QFP (Quad Flat Package) and SOP (Small Outline Package).
[0033]
FIG. 10 shows an X-ray image of BGA, where the presence / absence of solder and the shape of the solder are checked.
[0034]
FIG. 11 shows a flowchart of inspection by the substrate inspection apparatus of this example. First, the optical CCD camera 2 is set so that an optical image of a substrate to be inspected or an inspection site of the substrate can be captured, the optical image is captured (step S1), and FIG. 9 and FIG. The inspection described with reference is performed (step S2). Here, the non-defective product / defective product is discriminated by inspecting, for example, the presence / absence of components of various components such as BGA, the component polarity, the positional deviation, and the like, which are the targets of the optical image inspection (step S3). If the result of the inspection is NG, it is determined that the corresponding part on the board is defective.
[0035]
If the result of the inspection is OK in the determination processing in step S3, the process proceeds to the next X-ray image inspection step. The X-ray source 6 and the X-ray receiving CCD camera 3 are set so that an X-ray image of the inspection target substrate or the inspection site of the substrate can be captured, and the X-ray image is captured (step S4). The inspection described with reference to FIGS. 4 to 6 and 10 is performed based on the image (step S5). Here, for example, the amount of solder in BGA, the solder shape, the amount of general component solder, etc., which are the targets of the X-ray image inspection, are inspected, and a non-defective product / defective product is discriminated (step S6). If the result of the inspection is NG, it is determined that the corresponding part on the board is defective.
[0036]
If the result of the inspection in step S6 is OK, the process proceeds to processing of an X-ray image and an optical image. The above-described optical image and X-ray image of the substrate to be inspected are read from, for example, a storage unit such as the main memory 12, and the images are processed by combining the images as shown in FIG. 7 (step S7). Then, the inspection described with reference to FIGS. 7 and 8 is performed on the obtained processed image (step S8). Here, for example, the amount of solder of capacitors and other components, which are inspection targets of the processed image of the X-ray image and the optical image, is inspected, and a non-defective product / defective product is discriminated (step S9). If the result of the inspection is NG, it is determined that the corresponding part on the board is defective.
[0037]
If the result of the inspection in step S7 is OK, the inspected substrate is a non-defective product and the substrate inspection is terminated.
[0038]
In this inspection flowchart, the X-ray system and the optical system inspection means are provided in the same apparatus, so that the CPU 11 as the selection means can perform an X-ray image and an optical image, respectively, according to the type of components mounted on the board. It is possible to perform inspection efficiently while selecting an optimal method or an inspection method using a processed image. For example, depending on the part, after the optical image inspection in step S1 to step S3 is performed, if the X-ray image inspection is not necessary, the process skips to step S7 and performs the inspection using the processed image of the X-ray image / optical image. . Alternatively, if it is a part that cannot be inspected by the optical image inspection and the X-ray image inspection and needs to be inspected by the processed image, an inspection flow by various combinations such as starting from the inspection by the processed image in step S7 can be considered.
[0039]
For the selection by the CPU 11 described above, for example, a part to be mounted as a finished product is registered in the main memory 12 in advance, and an inspection method is selected according to the registered content. Alternatively, it is conceivable that an optical image is first captured, and an inspection method is selected by determining what components are mounted from the optical image.
[0040]
As described above, according to this example, it is possible to inspect components that have been difficult in the past by combining the X-ray image inspection and the optical image inspection in the component mounting board inspection.
[0041]
In addition, the substrate inspection apparatus of this example has an effect equivalent to two or more of these inspection apparatuses by processing both images rather than simply arranging the X-ray inspection apparatus and the optical inspection apparatus in series. Is obtained. In other words, the inspection is performed by using an optical inspection apparatus with the presence / absence of parts, component polarity, positional deviation, etc., and with the X-ray inspection apparatus using X-ray images for solder fillets, solder in BGA, etc. There is. If two units are arranged in a series, the functions of both units are added as they are to obtain the function of two units. However, when confirming a solder fillet, there are some which cannot distinguish between a component and solder, and this cannot be inspected by each of the above-described inspection devices alone. In this substrate inspection apparatus, inspection can be realized by combining and processing the optical image and the X-ray image.
[0042]
In addition, the present invention is not limited to the above-described embodiment, and in addition, there are X-rays irradiated from the X-ray source to the inspection target substrate, and light reflected from the inspection target substrate by illumination or the like. The present invention can also be applied to cases where they are on the same axis.
[0043]
Further, the present invention is not limited to the above-described embodiments, and various other configurations can be taken without departing from the gist of the present invention.
[0044]
【The invention's effect】
According to the present invention, the optical image and the X-ray image are combined and processed, and the processed composite image is used to determine whether the solder or the component is indistinguishable from the solder or the component in the X-ray image. Therefore, there is an effect that it is possible to realize inspection of parts which has been difficult in the past.
[0045]
In addition, the soldering quality is determined not only by the area and volume but also by the X-ray irradiation at once to obtain a wide luminance distribution on the board, and the solder shape calculated by this luminance distribution is used for soldering. There is an effect that it is possible to more accurately determine whether the quality is good or bad.
[0046]
Also, by creating a three-dimensional view of the solder part from the luminance distribution of the X-ray image, the solder state can be visually confirmed by adding this three-dimensional view of the solder part to the solder state calculated from the luminance distribution, and soldering is more accurate. There is an effect that it is possible to make a pass / fail judgment.
[0047]
In addition, since an optimum inspection based on an X-ray image, an optical image, a composite image, or a combination thereof is selected according to the type of components mounted on the board, there is an effect that the inspection can be performed efficiently. .
[Brief description of the drawings]
FIG. 1 is an apparatus configuration diagram showing an example of an embodiment of a substrate inspection apparatus of the present invention.
FIG. 2 is an optical image for explaining an example of an embodiment of the present invention.
FIG. 3 is an X-ray image for explaining an example of an embodiment of the present invention.
FIG. 4 is an X-ray image threshold display for explaining an example of an embodiment of the present invention.
FIG. 5 is a diagram showing an example of a solder fillet for explaining an example of an embodiment of the present invention.
FIG. 6 is an X-ray image 3D diagram for explaining an example of an embodiment of the present invention.
FIG. 7 is a processed image for explaining an example of an embodiment of the present invention.
FIG. 8 is another processed image for explaining an example of an embodiment of the present invention.
FIG. 9 is a BGA optical image for explaining an example of an embodiment of the present invention.
FIG. 10 is a BGAX line image for explaining an example of an embodiment of the present invention;
FIG. 11 is a flowchart for explaining a substrate inspection method according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Data collection device, 2 ... Optical camera, 3 ... X-ray camera, 4 ... Mechanism part, 5 ... Board | substrate to be examined, 6 ... X-ray source, 10 ... Data processing apparatus, 11 ... CPU, 12 ... Main memory, 13 ... Image board, 14 ... I / O board, 15 ... Motor board, 16 ... GUI,
17 ... System bus, 20 ... Solder part, 20a ... Solder part center of gravity position, 20b ... High brightness part center of gravity position, 21 ... Component chip, 22, 23 ... Solder fillet

Claims (2)

An X-ray imaging unit that captures a transmitted X-ray image of an X-ray irradiated to an object to be inspected on which a component is mounted;
A visible light imaging unit that images the inspection object;
A portion corresponding to the part of the optical image obtained by the visible light imaging unit is synthesized with an X-ray image including the part obtained by the X-ray imaging unit and solder fixing the component, and the X Image processing means for generating a composite image in which a part equivalent part of a line image is replaced with a part equivalent part of the optical image;
According to a component mounted on the inspection object, the X-ray image, the optical image, or a selection unit that selects an inspection based on a composite image of the X-ray image and the optical image ,
The image processing means obtains the difference between the centroid position of the entire solder of the solder portion in the X-ray image and the centroid position of the high-luminance portion of the solder portion in the X-ray image. A board inspection apparatus that inspects the shape of the solder based on the difference between the position and the position of the center of gravity of the high luminance portion of the solder portion . An X-ray imaging unit that captures a transmitted X-ray image of an X-ray irradiated to an object to be inspected on which a component is mounted;
A visible light imaging unit that images the inspection object;
A portion corresponding to the part of the optical image obtained by the visible light imaging unit is synthesized with an X-ray image including the part obtained by the X-ray imaging unit and solder fixing the component, and the X Image processing means for generating a composite image in which a part equivalent part of a line image is replaced with a part equivalent part of the optical image;
According to a component mounted on the inspection object, the X-ray image, the optical image, or a selection unit that selects an inspection based on a composite image of the X-ray image and the optical image ,
By the image processing means, the difference between the distance between the center of gravity of the entire solder of the opposing solder part in the X-ray image and the distance between the center of gravity of the high-luminance part of the opposing solder part in the X-ray image is calculated. The presence / absence of the component is inspected based on the difference between the distance between the center of gravity positions of the entire solder of the opposing solder portions and the distance between the center of gravity positions of the high brightness portions of the opposing solder portions.
Board inspection equipment.

Images