Appearance inspection device and appearance inspection method

Abstract

To provide a technique capable of inspecting lid deformation.SOLUTION: A visual inspection apparatus includes: a stage on which a semiconductor device having a lid is placed; a camera provided above the stage; a coaxial illumination device provided between the camera and the stage; an oblique illumination device provided between the camera and the stage; and a control device. The control device is configured to irradiate the semiconductor device with illumination light by the coaxial illumination device and the oblique illumination device, capture the semiconductor device by the camera to acquire an image, integrate the number of pixels of a predetermined pixel value by binarization processing of the image to acquire a determination value, and compare the determination value with a predetermined value to determine whether the semiconductor device is non-defective or defective.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an appearance inspection apparatus, and is applicable to, for example, an appearance inspection apparatus for semiconductor packages having lids. [Background technology]

[0002] In some FCBGA (Flip Chip Ball Grid Array) type semiconductor packages, the semiconductor chip mounted on the wiring board is covered with a cover called a lid, and the semiconductor chip and the lid are brought into contact with each other via a heat dissipation paste or the like, thereby functioning as a heat sink (for example, JP 2011-146415 A). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-146415 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, after a semiconductor package is completed, the semiconductor package may be pressed during an inspection process, which may cause deformation of the lid.

[0005] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0006] A representative aspect of the present disclosure can be briefly outlined as follows: A visual inspection apparatus includes a stage on which a semiconductor device having a lid is placed, a camera provided above the stage, a coaxial lighting device provided between the camera and the stage, an oblique lighting device provided between the camera and the stage, and a control device. The control device is configured to irradiate the semiconductor device with illumination light using the coaxial lighting device and the oblique lighting device, photograph the semiconductor device using the camera to obtain an image, binarize the image to add up the number of pixels with a predetermined pixel value to obtain a judgment value, and compare the judgment value with a predetermined value to determine whether the product is good or defective. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to inspect the lid for deformation. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing the outline of the structure of an FCBGA type semiconductor package. [Figure 2] FIG. 2 is a diagram showing a modification of the lid shown in FIG. [Figure 3] FIG. 3 is a diagram showing a schematic configuration of a visual inspection device according to an embodiment. [Figure 4] FIG. 4 is a conceptual diagram of a photographed image of a semiconductor package with a deformed lid. [Figure 5] FIG. 5 is an image diagram of a histogram of the image shown in FIG. [Figure 6] FIG. 6 is a conceptual diagram of an image obtained by binarizing the image shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the drawings. However, in the following description, the same components will be assigned the same reference numerals, and repeated description may be omitted. Note that, in order to clarify the description, the width, thickness, shape, etc. of each part may be shown schematically compared to the actual embodiment. Furthermore, the dimensional relationships, ratios, etc. of each element between multiple drawings do not necessarily match.

[0010] First, the structure of an FCBGA type semiconductor package having a lid will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view showing an outline of the structure of an FCBGA type semiconductor package.

[0011] In an FCBGA-type semiconductor package (semiconductor device) 1, the semiconductor chip 20 is covered with a cover called a lid 30. The lid 30 is made of a metal material with high thermal conductivity, such as copper. The lid 30 is bonded to the semiconductor chip at its ceiling 30b. The lid 30 is also bonded to the wiring substrate 10 only at its edge 30a. The lid edge 30a is an outer frame portion (flange) that contacts the wiring substrate 10. To enable the lid 30 to function as a heat sink, for example, after an underfill (UF) resin 21 has hardened, a heat dissipation paste 22 is applied to the backside of the semiconductor chip 20. The lid 30 is bonded to the wiring substrate 10, for example, as follows: An adhesive (lid adhesive resin) 23 is applied linearly onto the wiring substrate 10, the edge 30a of the lid 30 is bonded to the portion where the adhesive 23 has been applied, the lid 30 is attached, and the adhesive 23 is cured.

[0012] Next, the problem with the semiconductor package 1 will be described with reference to Fig. 2. Fig. 2 is a diagram showing deformation of the lid shown in Fig. 1.

[0013] In an inspection process after the semiconductor package 1 shown in FIG. 1 is completed, for example, in a screening test for determining whether a semiconductor package 1 is good or bad, lid deformation may occur as shown in FIG. 2. Specifically, if product misalignment occurs in a measurement section, such as a socket, on which the semiconductor package 1 is placed in a screening test device, the lid 30 on the upper surface of the semiconductor package 1 may be pressed by a measurement handler or the like that transports the semiconductor package 1. This may cause lid deformation. This lid deformation may displace the edge 30a of the lid 30 above a predetermined height from the wiring substrate 10. The distance between the bottom surface, where the edge 30a of the lid 30 is normally fixed, and the lower surface edge where the edge 30a of the lid 30 is raised due to deformation, is defined as the deformation amount (d).

[0014] Next, a visual inspection device capable of inspecting the above-mentioned lid deformation will be described with reference to Fig. 3. Fig. 3 is a diagram showing a schematic configuration of the visual inspection device according to the embodiment.

[0015] The visual inspection apparatus 100 includes a camera 110, a first lighting device 120, a second lighting device 130, a stage 140, and a control device 150. The camera 110 is installed, for example, directly above the stage 140, with its viewing angle facing vertically downward. The camera 110 is installed so that the semiconductor package 1 is located within its field of view. The lighting devices 120 and 130 emit light to brighten the semiconductor package 1 placed on the stage 140 so that the camera 110 can capture an image of it. With this configuration, the camera 110 can capture an image of the top surface of the semiconductor package 1. The camera 110 includes an imaging device 111 and a lens 112. The camera 110 quantifies the brightness (light intensity).

[0016] The illumination device 120 is disposed between the camera 110 and the stage 140. The illumination device 120 includes a surface-emitting illumination (light source) 121 and a half mirror (semi-transparent mirror) 122. Illumination light from the surface-emitting illumination 121 is reflected by the half mirror 122 on the same optical axis as the camera 110 and is irradiated onto the semiconductor package 1 on the stage 140. The scattered light irradiated onto the object to be imaged on the same optical axis as the camera 110 is reflected by the semiconductor package 1, and specularly reflected light of the scattered light passes through the half mirror 122 and reaches the camera 110, forming an image of the semiconductor package 1. The illumination device 120 is a coaxial epi-illumination (coaxial illumination) device.

[0017] The light source color of the surface emitting light 121 is a single color, for example, blue. It is preferable to use a light source whose output can be adjusted, such as a system that adjusts the light intensity by pulse dimming duty of an LED (Light Emitting Diode). The brightness of the light source can be adjusted to, for example, 256 (0 to 255) gradations.

[0018] The lighting device 130 is disposed between the camera 110 and the stage 140. The lighting device 130 is an oblique light bar light, which irradiates the semiconductor package 1 on the stage 140 at a predetermined angle with respect to the optical axis of the camera 110. Four oblique light bar lights are provided to face the four sides of the semiconductor package 1. The predetermined angle is, for example, 45 degrees ±10 degrees.

[0019] The light source color of the lighting device 130 is a single color, for example, red, which has a longer wavelength than the illumination light of the surface-emitting lighting 121. It is preferable to use a light source whose output can be adjusted, for example, a system that adjusts the light amount by the pulse dimming duty of an LED. The brightness of the light source can be adjusted to, for example, 256 (0 to 255) gradations.

[0020] The control device 150 includes a central processing unit (CPU), a storage device, and an input / output device. Image data captured by the camera 110 is stored in the storage device via an image capture device (capture board). The storage device is composed of a RAM (random access memory) in the main storage device and auxiliary storage devices such as an HDD (hard disk drive). The storage device stores programs (software) that control the operation of each of the above-mentioned parts of the appearance inspection device 100, as well as data such as inspection thresholds (described later). The CPU executes the programs stored in the main storage device. The input / output device is composed of a touch panel, a mouse, an image capture device (capture board), a monitor, a motor control device, an I / O signal control device, etc.

[0021] The CPU processes the stored image data and controls the driving units such as the XY table of the stage 140 and the lighting devices 120 and 130 via an I / O signal control device including a motor control device, sensor and switch control, etc.

[0022] It is difficult to directly observe lid deformation by photographing the semiconductor package 1 with a camera from above. Therefore, in this embodiment, the lid deformation area is shaded with illumination light from lighting devices 120 and 130. The semiconductor package 1 is photographed from above with camera 110, and the lid deformation is indirectly observed based on the brightness of the image of the semiconductor package 1.

[0023] The surface of the lid 30 is, for example, nickel-plated, and if the brightness of the lighting device is high (the illuminance on the surface of the lid 30 is high), even if the edge 30a of the lid 30 is deformed, the difference in brightness between the deformed part of the edge 30a and other parts will be small. Therefore, the brightness of the lighting devices 120 and 130 is adjusted to increase the difference in brightness. It is preferable to set the brightness of the lighting device 120, which irradiates the semiconductor package 1 with illumination light from directly above, relatively low. Since this illumination alone does not provide sufficient illumination, it is preferable to set the brightness of the lighting device 130, which irradiates the semiconductor package 1 with illumination light obliquely, slightly higher than the brightness of the lighting device 120.

[0024] An example of the settings of the lighting devices 120 and 130 is shown below. Brightness of lighting device 120: 5 to 10 (256 gradations) Brightness of lighting device 130: 15 to 20 (256 gradations) Illuminance on the surface of the semiconductor package 1: 70 to 85 (lx) Here, "5 to 10" means "5 or more and 10 or less." The same applies to other numerical ranges.

[0025] The method for detecting lid deformation will be described with reference to Figures 4 to 6. Figure 4 is an image of a captured image of a semiconductor package with lid deformation. Figure 5 is an image of a histogram of the image shown in Figure 4. Figure 6 is an image of an image obtained by binarizing the image shown in Figure 4.

[0026] (Image acquisition: Step S10) The control device 150 sets the lighting devices 120 and 130 to predetermined conditions, and the lighting devices 120 and 130 emit light, and the camera 110 captures an image of the semiconductor package 1 from above. The captured image is, for example, 8-bit grayscale data (256 gradations). As shown in FIG. 4, the captured image shows that the upper surface of the deformed portion DF of the edge 30a of the lid 30 is darker than the non-deformed portion.

[0027] (Binarization process: step S20) The control device 150 performs binarization processing within a predetermined threshold range on the image captured by the camera 110. The binarization processing is performed by creating a histogram (step S21), setting a threshold (step S22), and binarizing (step S23).

[0028] (Step S21) To set this threshold, the control device 150 creates the histogram shown in Figure 5. The horizontal axis is pixel value (a gradation indicating brightness, with higher values ​​being brighter), and the vertical axis is the number of pixels that appear. The area (A) with a high number of pixels that appears is a portion of the lid 30 where there is no lid deformation. On the side of the pixel value smaller than A, there is an area (B) with a slightly higher number of pixels that appear. B is a portion of the lid 30 where there is deformation. On the side of the pixel value smaller than B, there is an area (C) with a low number of pixels that appear. Furthermore, on the side of the pixel value larger than A, there is an area (D) with a low number of pixels that appear.

[0029] (Step S22) The control device 150 sets a first threshold (Th1) at the boundary between the area (A) and the area (B), and sets a second threshold (Th2) at the boundary between the area (B) and the area (C). By appropriately setting the lighting devices 120 and 130, the boundary between the area (A) and the area (B) and the boundary between the area (B) and the area (C) becomes clear, making it possible to set the first threshold (Th1) and the second threshold (Th2).

[0030] (Step S23) The control device 150 performs binarization by setting pixels having pixel values ​​between the first threshold (Th1) and the second threshold (Th2) (area (B)) to "1" (white), and setting pixels in areas having pixel values ​​other than those (areas (C), (A), and (D)) to "0" (black). In other words, the control device 150 extracts pixels whose pixel values ​​are within a predetermined range. By performing this binarization process, an image such as that shown in FIG. 6 is obtained, with the deformed areas of the lid appearing white.

[0031] (Blob analysis: Step S30) The control device 150 calculates the white area by accumulating the number of white pixels in the image shown in Fig. 6. The calculated white area (number of pixels) is used as a judgment value.

[0032] (Determination process: step S40) The control device 150 determines a defect when the judgment value exceeds a preset inspection threshold value. Here, the judgment value and the inspection threshold value are the number of pixels, and the greater the amount of deformation of the lid, the greater the judgment value.

[0033] A method for setting the inspection threshold will now be described. The inspection threshold is determined in advance before inspection. A large number of samples of the same product with different amounts of deformation are prepared for each product. Here, the amount of deformation of each sample is measured and known. For example, the sample may be mounted on the stage of the visual inspection device in the embodiment, and the difference in distance between the top surface of the wiring substrate 10 and the top surface of the edge 30a of the ridge 30 may be measured.

[0034] The control device 150 performs the above-described steps S10 to S30 for each sample to obtain each judgment value and its deformation amount. Based on the relationship between the acquired deformation amount and judgment value, the control device 150 stores the judgment value at which the deformation amount is equal to or greater than a predetermined value as an inspection threshold in the storage device of the control device 150. These processes are performed for each product.

[0035] According to this embodiment, it is possible to inspect for ridge deformation without using a three-dimensional inspection function such as a laser measurement function, a phase-shift measurement projector, etc. Furthermore, by inspecting for ridge deformation, it is possible to reduce the number of defective products shipped due to lid deformation.

[0036] The disclosure made by the present inventors has been specifically described above based on the embodiments, but it goes without saying that the present disclosure is not limited to the above embodiments and can be modified in various ways. [Explanation of symbols]

[0037] 100... Appearance inspection device 110···Camera 120 First lighting device 130 Second lighting device 140 Stage 150 Control device

Claims

1. a stage on which a semiconductor device having a lid is placed; a camera provided above the stage; a coaxial lighting device provided between the camera and the stage; an oblique lighting device provided between the camera and the stage; a control device; Equipped with The control device irradiating the semiconductor device with illumination light from the coaxial illumination device and the oblique illumination device, and capturing an image of the semiconductor device with the camera; The number of pixels having a predetermined pixel value is accumulated by binarizing the image to obtain a judgment value; The visual inspection device is configured to compare the judgment value with a predetermined value to judge whether the product is good or defective.

2. 2. The visual inspection apparatus according to claim 1, The control device a second semiconductor device whose lid is deformed and whose deformation amount is known is placed on the stage; irradiating the second semiconductor device with illumination light from the coaxial illumination device and the oblique illumination device, and capturing an image of the second semiconductor device with the camera; A measurement value is obtained by accumulating the number of pixels having a predetermined pixel value through binarization processing of the image; a visual inspection device configured to obtain the predetermined value based on the deformation amount of the lid of the second semiconductor device and the measurement value;

3. 3. The visual inspection apparatus according to claim 2, the illumination light of the coaxial illumination device is blue; the illumination light of the oblique illumination device is red, The control device is configured to set the brightness of the coaxial lighting device and the oblique lighting device so that deformation of the lid can be detected.

4. 4. The visual inspection apparatus according to claim 3, The visual inspection device is configured so that the control device sets the luminance of the coaxial lighting device to be lower than the luminance of the oblique lighting device.

5. irradiating an upper surface of a semiconductor device having a lid with illumination light from a coaxial illumination device and an oblique illumination device, and capturing an image of the upper surface of the semiconductor device with a camera; The number of pixels having a predetermined pixel value is accumulated by binarizing the image to obtain a judgment value; The visual inspection method includes comparing the judgment value with a predetermined value to judge whether the product is good or defective.

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