Mounting apparatus, inspection apparatus, element assembly method, and semiconductor device manufacturing method

Abstract

To provide a technique for improving the accuracy of inspection of bonded materials.SOLUTION: A mounting equipment comprises an imaging device directed at a bonding material having a mirror-reflective surface, an illumination device having a light source installed above the bonding material, and a control unit configured to inspect the bonding material based on multiple images obtained by the imaging device photographing the bonding material by changing the irradiation position of the light source.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to mounting devices and is applicable, for example, to die bonders using paste as a bonding material.

Background Art

[0002] Mounting devices such as die bonders are devices that attach (mount) elements onto a substrate or an element using a bonding material. The bonding material is, for example, resin paste, solder, or the like. The resin paste is a liquid adhesive, for example, silver paste such as silver epoxy or silver acrylic. Hereinafter, the resin paste is simply referred to as paste. The element is, for example, a semiconductor chip (hereinafter referred to as a die), a MEMS (Micro Electro Mechanical System), or the like. The substrate is, for example, a wiring board, a lead frame formed of a metal thin plate, a glass substrate, or the like.

[0003] For example, based on an image acquired using a camera and a lighting device, the position of the substrate on which the paste is applied is confirmed for positioning, or it is confirmed whether the paste applied to the substrate is applied in a predetermined shape and a predetermined amount at a predetermined position.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure aims to provide a technique for improving the accuracy of inspection of a bonding material. Other problems and novel features will become apparent from the description of this specification and the accompanying drawings.

Means for Solving the Problems

[0006] Note: There seems to be a typo in the original where "XX" is used in line ID=33. It should be something else, but I've translated it as is based on the rules.A brief overview of some of the representative disclosures is as follows: In other words, the mounting apparatus comprises an imaging device directed at a bonding material having a specular reflective surface, an illumination device having a light source provided above the bonding material, and a control device configured to inspect the bonding material based on a plurality of images obtained by the imaging device by changing the irradiation position of the light source. [Effects of the Invention]

[0007] According to this disclosure, it is possible to improve the accuracy of inspection of jointed materials. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic top view showing a die bonder in an embodiment. [Figure 2] Figure 2 is a diagram illustrating the schematic configuration as seen from the direction of arrow A in Figure 1. [Figure 3] Figure 3 is a block diagram showing the schematic configuration of the die bonder control system shown in Figure 1. [Figure 4] Figure 4 is a flowchart showing a method for manufacturing a semiconductor device using the die bonder shown in Figure 1. [Figure 5] Figure 5 shows the preform camera, lighting device, and paste applied to the substrate in the embodiment. [Figure 6] Figures 6(a) to 6(c) show the paste image when only one light source of the lighting device shown in Figure 5 is turned on. [Figure 7] Figure 7(a) shows the relative positions of the preform camera, light source, and paste. Figure 7(b) shows the position of the bright spot within the field of view of the preform camera. [Figure 8] Figure 8 shows the position of the bright spot within the field of view of the preform camera. [Figure 9] Figure 9 is a diagram illustrating a method for calculating the Z position of a bright spot based on its coordinates and tangential direction on a plane. [Figure 10] Figure 10(a) shows an image where there is a correlation between the light source and the bright spot. Figure 10(b) shows an image where there is little correlation between the light source and the bright spot. Figure 10(c) shows an image where the paste shape is complex. [Figure 11] Figure 11 shows side and top images of the applied paste. [Figure 12] Figure 12 shows the paste overflowing and spreading. [Modes for carrying out the invention]

[0009] The embodiments will be described below with reference to the drawings. However, in the following description, the same reference numerals will be used for the same components, and repeated explanations may be omitted. In addition, the drawings may be schematically represented in terms of the width, thickness, shape, etc. of each part, rather than in the actual embodiment, in order to make the explanation clearer, but these are merely examples and do not limit the interpretation of this disclosure.

[0010] The configuration of the die bonder in an embodiment of the mounting device will be explained with reference to Figures 1 and 2.

[0011] The die bonder 10 is broadly composed of a die supply unit 1 that supplies dies D to be mounted on a substrate S, a pickup unit 2, an intermediate stage unit 3, a preform unit 9, a bonding unit 4, a transport unit 5, a substrate supply unit 6, a substrate unloading unit 7, and a control unit (control device) 8 that monitors and controls the operation of each unit. The Y-axis direction is the front-to-back direction of the die bonder 10, and the X-axis direction is the left-to-right direction. The die supply unit 1 is located on the front side of the die bonder 10, and the bonding unit 4 is located on the back side. Here, the substrate S has multiple product areas (hereinafter referred to as attachment areas P) that will form the final package. For example, if the substrate S is a lead frame, the attachment areas P have tabs on which the dies D are placed.

[0012] The die supply unit 1 includes a wafer holding stage 12 that holds the wafer 11, and a separation unit 13 shown by a dotted line that separates the die D from the wafer 11. The wafer holding stage 12 is moved in the XY directions by a driving means (not shown) and moves the picked-up die D to the position of the separation unit 13. The separation unit 13 is moved in the vertical direction by a driving means (not shown). The wafer 11 is adhered onto a dicing tape 16 and is divided into a plurality of dies D. The dicing tape 16 to which the wafer 11 is attached is held by a wafer ring (not shown).

[0013] The pickup unit 2 includes a pickup head 21, a Y driving unit 23, driving units (not shown) that move the collet 22 up and down, rotate it, and move it in the X-axis direction, and a wafer recognition camera 24. The pickup head 21 has a collet 22 that sucks and holds the separated die D at its tip, picks up the die D from the die supply unit 1, and places it on the intermediate stage 31. The Y driving unit 23 moves the pickup head 21 in the Y-axis direction. The wafer recognition camera 24 grasps the pickup position of the die D picked up from the wafer 11.

[0014] The intermediate stage unit 3 includes an intermediate stage 31 that temporarily places the die D, and a stage recognition camera 32 for recognizing the die D on the intermediate stage 31.

[0015] The preform unit 9 includes a syringe 91, a driving unit 93, a preform camera 94 as an imaging device, and a preform stage 96. The syringe 91 applies paste to the substrate S that has been transported to the preform stage 96 by the transport unit 5. The driving unit 93 moves the syringe 91 in the X-axis direction, Y-axis direction, and vertical direction. The preform camera 94 grasps the application position etc. of the syringe 91. The preform stage 96 is raised when applying the paste to the substrate S and supports the substrate S from below. The preform stage 96 has suction holes (not shown) for vacuum-sucking the substrate S and can fix the substrate S.

[0016] The bonding unit 4 includes a bond head 41, a Y drive unit 43, a substrate recognition camera 44, and a bond stage 46. The bond head 41 has a collet 42 that adsorbs and holds the die D at its tip, similar to the pickup head 21. The Y drive unit 43 moves the bond head 41 in the Y-axis direction. The substrate recognition camera 44 images a position recognition mark (not shown) in the attachment region P of the substrate S to recognize the bond position. When the die D is placed on the substrate S, the bond stage 46 is raised to support the substrate S from below. The bond stage 46 has suction holes (not shown) for vacuum-sucking the substrate S and can fix the substrate S. With such a configuration, the bond head 41 corrects the pickup position and orientation based on the imaging data of the stage recognition camera 32 and picks up the die D from the intermediate stage 31. Then, based on the imaging data of the substrate recognition camera 44, the bond head 41 bonds (places and adheres) the die D onto the attachment region P where the paste of the conveyed substrate S is applied.

[0017] The conveyance unit 5 includes a substrate conveyance claw 51 that grips and conveys the substrate S, and a conveyance lane 52 as a conveyance path along which the substrate S moves. The substrate S is moved by driving a nut (not shown) of the substrate conveyance claw 51 provided in the conveyance lane 52 with a ball screw (not shown) provided along the conveyance lane 52. With such a configuration, the substrate S moves from the substrate supply unit 6 along the conveyance lane 52 via the application position to the bond position, and after bonding, moves to the substrate discharge unit 7 and delivers the substrate S to the substrate discharge unit 7.

[0018] The control system of the die bonder 10 will be described with reference to FIG. 3. [[ID=]]

[0019] The control system 80 comprises a control unit 8, a drive unit 86, a signal unit 87, and an optical system 88. The control unit 8 is broadly composed of a control / arithmetic unit 81 mainly consisting of a CPU (Central Processing Unit), a storage device 82, an input / output device 83, a bus line 84, and a power supply unit 85. The storage device 82 has a main storage device 82a composed of RAM (Random Access Memory) etc. which stores processing programs etc., and an auxiliary storage device 82b composed of HDD (Hard Disk Drive) etc. which stores control data and image data necessary for control. The input / output device 83 has a monitor 83a which displays the device status and information etc., a touch panel 83b which inputs operator instructions, a mouse 83c which operates the monitor, and an image acquisition device 83d which acquires image data from the optical system 88. The input / output device 83 also has a drive unit 86, a motor control device 83e which controls the drive unit 86, and an I / O signal control device 83f which acquires or controls signals from the signal unit 87.

[0020] The drive unit 86 includes the XY table (not shown) of the die supply unit 1, the Y drive unit 23 which is the ZY drive axis of the pickup head 21 shown in Figure 1, the drive unit 93 which is the ZY drive axis of the syringe 91, and the Y drive unit 43 which is the ZY drive axis of the bond head 41. The signal unit 87 includes switches and potentiometers that control various sensor signals and the brightness of lighting devices. The optical system 88 includes the wafer recognition camera 24, preform camera 94, stage recognition camera 32, and substrate recognition camera 44 shown in Figure 1 or Figure 2. The control and calculation unit 81 acquires necessary data via the bus line 84, performs calculations, and sends information to control the bond head 41 and monitor 83a, etc.

[0021] The control unit 8 stores image data captured by the optical system 88 via the image acquisition device 83d in the storage device 82. Based on the stored image data, programmed software uses the control and calculation device 81 to position the die D and substrate S, inspect the application pattern of the paste-like adhesive, and inspect the surfaces of the die D and substrate S. Based on the positions of the die D and substrate S calculated by the control and calculation device 81, the software moves the drive unit 86 via the motor control device 83e. This process positions the die D on the wafer 11, and the drive units of the die supply unit 1 and bonding unit 4 operate to bond the die D onto the substrate S. The recognition camera used in the optical system 88 digitizes light intensity and color.

[0022] The bonding process (method of manufacturing a semiconductor device), which is one step in the manufacturing process of a semiconductor device using the die bonder 10, will be explained with reference to Figure 4. In the following explanation, the operation of each part that makes up the die bonder 10 is controlled by the control unit 8.

[0023] (Wafer loading process (process S1)) A wafer ring (not shown) is loaded into the die bonder 10. The loaded wafer ring is then supplied to the die supply unit 1. Here, the wafer ring holds a dicing tape 16 to which dies D, separated from the wafer 11, are attached.

[0024] (Substrate loading process (process S2)) A magazine (not shown) containing the circuit board S is loaded into the die bonder 10. The loaded magazine is supplied to the circuit board supply unit 6. In the circuit board supply unit 6, the circuit board S is fixed to the circuit board transport claws 51.

[0025] (Pickup process (process S3)) After step S1, the wafer holder 12 is moved so that the desired die D can be picked up from the dicing tape 16. The die D is photographed by the wafer recognition camera 24, and the die D is positioned and its surface inspected based on the image data acquired by the photograph.

[0026] The positioned die D is peeled from the dicing tape 16 by the peeling unit 13 and the pickup head 21. The die D, peeled from the dicing tape 16, is attracted and held by a collet 22 provided on the pickup head 21, and is transported to and placed on the intermediate stage 31.

[0027] The die D on the intermediate stage 31 is photographed by the stage recognition camera 32, and the die D is positioned and its surface inspected based on the image data acquired through the photography. By processing the image data, the amount of displacement (in the X, Y, and θ directions) of the die D on the intermediate stage 31 from the die position reference point of the die bonder 10 is calculated, and positioning is performed. The die position reference point is a predetermined position on the intermediate stage 31 that is held in advance as the initial setting of the device. The surface inspection of the die D is performed by processing the image data.

[0028] The pickup head 21, which has transported die D to the intermediate stage 31, is returned to the die supply unit 1. Following the procedure described above, the next die D is peeled off from the dicing tape 16, and thereafter, die D is peeled off one by one from the dicing tape 16 following the same procedure.

[0029] (Preform process (Process S4)) After step S2, the substrate S is transported to the preform stage 96 by the transport unit 5. The surface of the substrate S before coating is photographed by the preform camera 94, and the surface to which the paste should be applied is confirmed based on the image data acquired by the photograph. If there are no problems with the surface to be coated, the position where the paste will be applied to the substrate S supported by the preform stage 96 is confirmed and positioned. Positioning is performed by pattern matching or the like, similar to the bonding unit 4.

[0030] The paste is injected from the nozzle at the tip of the syringe 91 and applied according to the trajectory of the nozzle. The nozzle is driven by the drive unit 93 in the XYZ axes to apply the paste in the desired shape, and the paste is applied (drawn) in a free trajectory, such as an X shape or a cross shape, by following the trajectory of the nozzle. In addition to the nozzle, a stamp head may also be provided at the tip of the syringe 91.

[0031] The applied paste is photographed by the preform camera 94. Based on the image acquired by the photograph, it is confirmed whether the paste has been applied accurately, and an inspection (visual inspection) of the applied paste is performed. In other words, the visual inspection confirms whether the applied paste has been applied in a predetermined location, shape, and quantity. The inspection contents include, for example, the presence or absence of paste, the application area, and the application shape (insufficient, overflow). The inspection is performed by methods such as counting the number of pixels after separating the paste area using binarization processing, comparison by difference, comparison of scores by pattern matching, and shape determination by contour extraction.

[0032] (Bonding process (Process S5)) If there are no problems with the coating, the substrate S is transported to the bond stage 46 by the transport unit 5. The substrate S placed on the bond stage 46 is photographed by the substrate recognition camera 44, and image data is acquired through the photography. By processing the image data, the amount of displacement of the substrate S from the substrate position reference point of the die bonder 10 (in the X, Y, and θ directions) is calculated. The substrate position reference point is a predetermined position of the bonding unit 4, which is held as the initial setting of the device.

[0033] In step S3, the suction position of the bond head 41 is corrected based on the amount of displacement of the die D on the intermediate stage 31 calculated, and the die D is picked up by the collet 42. The die D is bonded to a predetermined location on the substrate S supported by the bond stage 46 by the bond head 41, which has picked up the die D from the intermediate stage 31. The die D bonded to the substrate S is photographed by the substrate recognition camera 44, and an inspection is performed based on the image data acquired by the photograph to determine whether the die D has been bonded to the desired position.

[0034] The bond head 41, having bonded die D to the substrate S, is returned to the intermediate stage 31. Following the procedure described above, the next die D is picked up from the intermediate stage 31 and bonded to the substrate S. This is repeated until die D is bonded to all attachment areas P on the substrate S.

[0035] (Substrate unloading process (process S6)) The substrate S to which the die D is bonded is transported to the substrate ejection section 7. In the substrate ejection section 7, the substrate S to which the die D is bonded is removed from the substrate transport claws 51 and stored in the magazine. The magazine containing the substrate S is ejected from the die bonder 10.

[0036] As described above, die D is mounted on substrate S and discharged from die bonder 10. Substrate S with die D mounted is transported to wire bonding process, where the electrodes of die D are electrically connected to the electrodes of substrate S via Au wire or the like. Substrate S is transported to molding process, where die D and Au wire are sealed with molding resin (not shown) to complete the package.

[0037] Figure 5 illustrates the lighting equipment used when paste PA is captured by the preform camera 94.

[0038] The preform camera 94 is positioned above the paste PA applied to the substrate S. The illumination device 95 is positioned below the preform camera 94 and above the paste PA. The preform camera 94, the illumination device 95, and the control unit 8 constitute an inspection device for the amount of bonding material.

[0039] The preform camera 94 is preferably a camera (CMOS camera) using a CMOS (Complementary Metal Oxide Semiconductor) image sensor capable of high-speed data transfer. More preferably, the preform camera 94 is a back-illuminated CMOS camera with high sensitivity. Note that the preform camera 94 in this embodiment is not limited to a CMOS camera, and may be, for example, a camera using a CCD (Charge Coupled Devices) image sensor.

[0040] The lighting device 95 is constructed by arranging multiple light sources 95a to 95l in a dome (hemispherical shell) shape. This allows for a multi-point light source. Each light source 95a to 95l can be turned on and off individually.

[0041] The angle of incidence of the light emitted from light sources 95e to 95h onto the paste PA (the angle with respect to the optical axis of the preform camera 94) is smaller than the angle of incidence of the light emitted from light sources 95a to 95d onto the paste PA. The angle of incidence of the light emitted from light sources 95i to 95l is smaller than the angle of incidence of the light emitted from light sources 95e to 95h onto the paste PA. For example, light sources 95a to 95d are located in the same horizontal plane. Light sources 95e to 95h are located in the same horizontal plane above light sources 95a to 95d. Light sources 95i to 95l are located in the same horizontal plane above light sources 95e to 95h.

[0042] Each of the light sources 95a to 95l is a point light source. Each of the light sources 95a to 95l is, for example, an LED (Light Emitting Diode) light source output through a fiber with a diameter of approximately 1 mm or less, preferably several hundred μm. Alternatively, the lighting device 95 may be a dome lighting system configured by providing multiple light sources, each composed of an LED (Light Emitting Diode), on the inner surface of a dome. In this case, the emission position of the illumination light can be changed by individually turning the LEDs on and off. Note that the number of light sources can also be increased by moving one or more light sources. For example, when moving multiple light sources, the lighting device 95 may be equipped with light sources 95a, 95e, and 95i, and configured so that light sources 95a, 95e, and 95i each move within the same plane.

[0043] The control unit 8 acquires the position where the light emitted from each light source of the illumination device 95 is directly reflected (direct light reflection position), and measures the shape of the paste PA, which is the liquid surface, from the acquired direct light reflection position. Bright spots are formed at the direct light reflection positions. The more light sources there are, the higher the resolution of the measurement can be.

[0044] The method for measuring the shape of paste PA will be explained using Figures 6(a), 6(b), 6(c), 7(a), 7(b), 8, and 9.

[0045] (photograph) Figure 6(a) shows an image when only light source 95a is lit, Figure 6(b) shows an image when only light source 95b is lit, and Figure 6(c) shows an image when only light source 95c is lit.

[0046] As shown in Figures 6(a) to 6(c), the control unit 8 lights up the light sources 95a, 95b, and 95c one by one, and the preform camera 94 captures the bright spots BS1, BS2, and BS3 formed by direct reflection from the surface of the paste PA for each light source. The light sources 95d to 95l are also lit up one by one, and the paste PA is captured. In the drawings, the paste PA is shown as black, and the bright spots BS1, BS2, and BS3 are shown as white.

[0047] (Calculation of the center of the bright spot) As shown in Figures 6(a) to 6(c), the bright spots BS1, BS2, and BS3 are not points but have shapes such as ellipses, so the control unit 8 calculates the center of each bright spot (bright spot center) in each image. The calculated bright spot center is set as the bright spot position. The method for determining the bright spot center can be simple, such as the center of the region (the center of the upper / lower or left / right limit points), or it can be the centroid, the point of maximum luminosity, or the center of the maximum inscribed circle, depending on the degree of shape deformation.

[0048] Furthermore, it is desirable to minimize the surface area of ​​the light source so that the bright spot is as close to a point as possible. In other words, it is desirable that the field of view of the light source be as small as possible from the position of reflection of direct light where the bright spot is formed. Also, it is desirable that the light source be as bright as possible. The calculation of the center of the bright spot does not have to be done after each photograph, but can be done all at once after all photographs have been taken.

[0049] (Calculating the shape of the paste) The control unit 8 calculates the reflection point in three-dimensional space from the center (position of the bright spot) of the bright spot in the calculated two-dimensional image to obtain the shape of the paste. To avoid making the explanation too complicated, the following example will describe a case where the light source is located on the X-axis.

[0050] The method for calculating the angle of the reflective surface where bright spots are formed will be explained using Figures 7(a) and 7(b).

[0051] The preform camera 94 is positioned far enough away from the paste PA so that it can always be considered to be in the same direction from the perspective of the paste PA. In other words, the distance between the preform camera 94 and the paste PA (shooting distance) is sufficiently large relative to the size of the paste PA. For example, the shooting distance is about 100 mm, and the paste width is about 0.3 to 10 mm. In Figure 7(a), for convenience, the preform camera 94 is assumed to be directly above the paste PA, but the direction of the preform camera 94 does not necessarily have to be directly above the paste PA. It is sufficient if it can be approximated as being in a constant direction across the entire paste area being photographed.

[0052] One of the light sources 95a to 95l shown in Figure 5 will be described as light source LS. Light source LS is a point light source and is considered a parallel light source because its distance from paste PA is sufficiently long. The light emitted from light source LS is directed towards the center O of the field of view of preform camera 94 on the surface of substrate S. The positions of light source LS and preform camera 94 from the center O of the field of view are known. Since light source LS is parallel light, the direction of propagation of the emitted light is known. Also, the direction of propagation of the reflected light in paste PA is vertical and is known. That is, the vector with center O as the starting point and the position of light source LS as the ending point, and the vector with center O as the starting point and the position of preform camera 94 as the ending point are known. Therefore, the angle (θ) between the emitted light and the reflected light from light source LS can be calculated as it is the angle between the two vectors.

[0053] If φ is the angle (normal direction of the reflecting surface) of the reflective surface where the bright spot BS is formed by the light source LS, then it can be calculated from θ by the law of reflection. That is, φ = θ / 2. The calculated φ is the angle it makes with the vertical direction, as well as the angle (slope of the tangent TD) of the reflecting surface made with the X direction (direction of the contact surface) and the horizontal plane.

[0054] As shown in Figure 7(b), the position of the bright spot BS formed by the light source LS from the center O of the field of view CV of the preform camera 94 is X BS Therefore, X BS This can be calculated from images captured by the preform camera 94.

[0055] Next, we will explain how to calculate the position of the bright spot in the Z direction (Z position, height) using Figures 8 and 9.

[0056] As shown in Figure 8, we will now describe the case where four bright spots BSa, BSb, BSc, and BSd are formed. Let Xa, Xb, Xc, and Xd be the positions of the four bright spots BSa, BSb, BSc, and BSd from the center O of the field of view CV of the preform camera 94.

[0057] As shown in Figure 9, the position where the bright spot BSa is formed and the tangent line TD to the reflective surface on which the bright spot BSa is formed are positioned on the X-axis. Similarly, the position where the bright spot BSb is formed and the tangent line TDb to the reflective surface on which the bright spot BSb is formed are positioned on the X-axis, the position where the bright spot BSc is formed and the tangent line TDc to the reflective surface on which the bright spot BSc is formed are positioned on the X-axis, and the position where the bright spot BSd is formed and the tangent line TDd to the reflective surface on which the bright spot BSd is formed are positioned on the X-axis. Here, if the inclinations of the tangent lines TDa, TDb, TDc, and TDd are φa, φb, φc, and φd, respectively, then φa < φb < φc < φd. Typically, the inclination of the paste surface relative to the substrate increases as it moves away from the center or center line.

[0058] The Z positions of the bright points BSa and BSb and the tangents TDa and TDb are positioned such that IPa, the intersection point of the two tangents TDa and TDb to adjacent bright points BSa and BSb, lies at the midpoint CPa between the two bright points BSa and BSb. Here, the midpoint CPa is located at a distance of |Xa+(Xb-Xa) / 2| from the field center O.

[0059] The Z positions of the bright points BSb and BSc and the tangents TDb and TDc are positioned such that the intersection point IPb of the two tangents TDb and TDc lies at the midpoint CPb of the two bright points BSb and BSc. Here, the midpoint CPb is located at a distance of |Xb+(Xc-Xb) / 2| from the field center O.

[0060] The Z positions of the bright points BSc, BSd and the tangents TDc, TDd are positioned such that the intersection point IPc of the two tangents TDc, TDd is located at the midpoint CPc of the two bright points BSc, BSd. Here, the midpoint CPc is located at a distance of |Xc+(Xd-Xc) / 2| from the field center O.

[0061] This allows us to determine the Z positions of the intersection points IPa to IPC and the bright points BSa to BSD, and thus the shape (volume) of the paste can be approximately calculated from the polygon formed by connecting these intersection points IPa to IPC and the bright points BSa to BSD. Note that the interpolation method described above is just one example, and other methods such as spline interpolation or Lagrangian interpolation may also be used.

[0062] The Z-position value of the outermost bright spot can be an offset value applied to the entire set of bright spots. As the die bonder only needs to monitor relative quantities, for example, as shown in Figure 8, the Z-position value of the outermost bright spot BSd may be set to 0, or it may be set to a predetermined value other than 0. In other words, the Z-position value of the outermost bright spot can be provisionally determined. Alternatively, the reflective surface at the paste boundary point may be provisionally set to a certain angle (such as perpendicular or close to it).

[0063] The light source LS may be moved in a direction that brings it closer to the horizontal plane containing the substrate surface, and the position where the bright spot contacts the paste contour surface (the maximum diameter at which the bright spot can be photographed) may be searched. This allows the height of the outermost bright spot to be approximated to 0, making it possible to measure the absolute amount of paste.

[0064] To further clarify this embodiment, several comparative examples will be described.

[0065] (First comparative example) The first comparative example will be explained using Figures 10(a), 10(b), and 10(c).

[0066] In the lighting device shown in Figure 5, it is conceivable to light up all light sources 95a to 95l to form multiple bright spots. This is referred to as the first comparative example. In the first comparative example, as shown in Figure 10(a), it is desirable that the bright spots, which are the reflection positions of each light source, can be roughly predicted in advance. Here, bright spot BS1 is the bright spot formed by light source 95a, bright spot BS2 is the bright spot formed by light source 95b, bright spot BS3 is the bright spot formed by light source 95c, and bright spot BS4 is the bright spot formed by light source 95d.

[0067] However, as shown in Figure 10(b), if the shape of the object to be measured is not stable, there is no regularity (correlation with the light source) in the position of the bright spots shown in white, making it difficult to determine which bright spot corresponds to which light source, and thus measurement becomes impossible.

[0068] Furthermore, as shown in Figure 10(c), when the shape of the paste is complex, there may be more than one bright spot for a single light source, and the use of multiple light sources makes it even more difficult to distinguish between the combination of light source and bright spot.

[0069] In this embodiment, the correlation between the light source and the bright spot can be maintained by individually turning on each light source and taking a photograph each time.

[0070] (Second Comparative Example) To solve the aforementioned problems in the first comparative example, it is conceivable to ensure correlation between light sources and bright spots by changing the wavelength of each light source and installing a camera capable of color discrimination. This is called the second comparative example. In the second comparative example, there is a limit to the number of colors that can be separated, which limits the number of points in the multi-point light source. In addition, the second comparative example is affected by the spectral reflectance characteristics (reflection spectrum) of the subject, and may not be usable depending on the color of the colored liquid.

[0071] In this embodiment, the correlation between the light source and the bright spot can be maintained by individually illuminating each light source and taking a photograph each time. As a result, there is no need to change the wavelength of each light source, and therefore the problems of the second comparative example described above are not encountered.

[0072] (Third comparative example) A third comparative example will be explained using Figures 11 and 12.

[0073] One possible method for inspecting the amount of paste applied is to use a camera positioned above the paste (an overhead camera) to photograph the paste and measure its area. This is referred to as the third comparative example. However, photography from an overhead camera only reveals the application area. For example, the viscosity of paste varies with temperature, resulting in different surface tensions. Therefore, as shown in the side view of Figure 11, even if there is a difference in the angle (contact angle) between the paste PA and the substrate S, the application area can be the same, as shown in the image of Figure 11. In other words, even with the same application area, the amount applied (volume or mass) will differ and is not constant due to differences in the state of buildup caused by surface tension, etc.

[0074] For example, a minute amount of paste (a fine area with a flat surface area smaller than the minute die) is applied to a minute die (e.g., about 1 mm square), but the amount of paste applied is easily affected by slight changes in the height of the syringe during application. Furthermore, when measuring the amount applied in a fine area using the third comparative example, the measured amount may differ significantly from the actual amount due to the surface tension of the paste PA. If this difference in application amount occurs, it will affect the amount of paste PA overflow (HD) and creep (HA) when the die is bonded to the substrate, as shown in Figure 12. In the case of a minute die, even a slight difference in application amount results in a large rate of change, thus significantly affecting the bonding process.

[0075] The miniaturization of microdies is advancing, and they are becoming more complex, including those with MEMS structures in addition to simple dies. Paste application technology also requires micro-volume application, and the control of the application amount needs to be more precise. Therefore, in order to control the application amount, it is necessary for the die bonder itself, which performs the application process, to be able to measure or inspect the application amount.

[0076] In this embodiment, the amount of paste applied can be calculated more accurately, making it possible to measure or inspect the amount applied to a micro-die, and enabling more precise control of the application amount.

[0077] (Other comparative examples) Other possible methods include changing the focal position of a vertically positioned camera (directly above) and summing the focal positions to infer the shape (fourth comparative example), using a stereo camera (multiple cameras) to recognize the shape three-dimensionally (fifth comparative example), and using a zebra light source with a slit in a parallel light source to create a striped shadow and project a striped pattern (sixth comparative example).

[0078] The methods in the fourth to sixth comparative examples utilize images to determine the position of the surface, and therefore assume that the target surface exhibits diffuse reflection. In the case of objects where specular reflection is dominant, such as liquid surfaces like pastes, the positional relationship and image of the reflected light source have a strong influence, making it difficult to infer the position of the reflective surface.

[0079] In transparent liquids, light coming from within the liquid surface is almost always dominant. Since specular reflection from the liquid surface is out of focus, we can only focus on the slight diffuse light on the surface. However, the amount of light from the internal reflection is exponentially greater, and the diffuse light is overwhelmed by it. As a result, the methods used in the fourth and fifth comparative examples cannot focus on the surface. Pastes can be transparent or translucent, and some contain fine particulate metals such as silver, making surface detection difficult.

[0080] In the method according to the sixth comparative example, since the diffuse reflector does not depend on the law of reflection, the image becomes striped depending on the position illuminated by the zebra light source formed by the parallel light source. The hemispherical portion formed by the paste, etc., forms a striped pattern depending on the position where the light source reaches. In contrast, in the case of specular reflection, since it follows the law of reflection, when parallel light reaches the surface, the reflected light is not necessarily focused on the camera. Therefore, in the method according to the sixth comparative example, in the case of specular reflection, only the background scenery appears bent on the surface.

[0081] The embodiment can detect the surface of a paste as a specularly reflective liquid, or the surface of a paste that is transparent, translucent, or contains fine particulate metals such as silver. Furthermore, the method of the embodiment can be applied not only to pastes but also to the detection of specularly reflective metal surfaces such as solder. In other words, it can measure or inspect the volume of a three-dimensional liquid or metal having a specularly reflective surface.

[0082] In this embodiment, the amount of paste applied can be monitored, thus providing one or more of the following effects.

[0083] (1) The amount of coating can be inspected and measured after each coating or at regular intervals during the production process.

[0084] (2) Based on the amount of coating measured in (1) above during the production process, the coating amount can be stabilized by issuing a warning or error for abnormal coating amounts, or by providing feedback on increasing or decreasing the coating amount.

[0085] (3) The above (2) makes it possible to stabilize the amount of paste that spills out and the amount that creeps up after bonding.

[0086] (4) The yield of products assembled by the die bonder can be improved.

[0087] The disclosure made by the Discloser has been described in detail based on embodiments, but it goes without saying that the disclosure is not limited to the above embodiments and can be modified in various ways.

[0088] For example, although the embodiment described measuring the shape of the paste immediately after application (application amount inspection), it can also be applied to inspecting the wettability of the paste after bonding (amount of paste overflow and creeping), measuring the shape of the solder, and inspecting the solder fillet (amount of solder overflow and creeping).

[0089] Furthermore, although a point light source was described as an example of an illumination device in the embodiment, a ring light may also be used as the illumination device. This makes it possible to acquire contour-like images at equal inclination angles on the surface of the paste, thereby improving the inspection speed.

[0090] Furthermore, although the embodiment described a circular paste in a top view, it can also be applied to inspecting paste formed by application (penlight, drawing) while moving the nozzle.

[0091] Furthermore, although the embodiment describes an example of inspection using a preform camera, inspection may also be performed using a substrate recognition camera or a bond camera.

[0092] Furthermore, although a point light source was described as an example of an illumination device in the embodiment, coaxial illumination using point light sources or parallel light sources may also be added to perform the inspection. This makes it possible to acquire an image with φ=0 and perform an external inspection.

[0093] In this embodiment, an intermediate stage section 3 is provided between the die supply section 1 and the bonding section 4. The die D picked up from the die supply section 1 by the pickup head 21 is placed on the intermediate stage 31, and the die D is picked up again from the intermediate stage 31 by the bond head 41 and bonded to the transported substrate S. However, the die D picked up from the die supply section 1 by the bond head 41 may also be bonded to the substrate S.

[0094] Furthermore, although a die bonder was used as an example in this embodiment, the method can also be applied to flip-chip bonders and chip mounters. [Explanation of Symbols]

[0095] 8. Control Unit (Control Device) 10. Die bonder (assembly device) 94. Preform camera (imaging device) 95. Lighting equipment 95a~95l...Light source PA paste (bonding material)

Claims

1. An imaging device directed at a bonding material, which is solder or resin paste, having a specular reflective surface, An illumination device having a light source provided above the joining material, A control device is configured to inspect the amount of coating applied by changing the position of the light source, thereby changing the position of the bright spots which are reflection points of the light emitted from the light source on the surface of the bonding material, and calculating the three-dimensional shape of the bonding material based on a plurality of images obtained by the imaging device capturing the bonding material. Equipped with, The irradiation position of the light source can be changed within the horizontal plane. A mounting device in which the light sources are arranged in different horizontal planes such that the angle of incidence of the light irradiated onto the bonding material changes.

2. In the mounting apparatus of claim 1, The control device is Based on the multiple images in which the bright spots were captured, the positions of the multiple bright spots within the images are calculated. Based on the positions of multiple bright spots in the aforementioned image, the positions of multiple bright spots in space are calculated. A mounting device configured to calculate the shape of the bonding material based on the position of a bright spot in the aforementioned space.

3. In the mounting apparatus of claim 2, The control device is configured to calculate the position of the bright spot in space based on the position of the bright spot in the image, the position of the light source, and the position of the imaging device.

4. In the mounting apparatus of claim 3, The control device is Based on the position of the bright spot in the image, the position of the light source, and the position of the imaging device, the normal direction of the surface of the bonding material at the position of the bright spot in the image is calculated. Based on the normal direction, the tangential direction of the surface of the bonding material at the bright spot position in the image is calculated. Based on the position of the bright spot in the image and the tangential direction, the position of the bright spot in space is calculated. A mounting device configured to calculate the shape of the bonding material based on the tangential direction and the position of the bright spot in space.

5. In the mounting apparatus of claim 4, The control device is configured to change the irradiation position by moving the light source.

6. In the mounting apparatus of claim 5, The control device is configured to search for the position in which the bright spot contacts the contour surface of the bonding material.

7. In the mounting apparatus of claim 4, The control device is configured to provisionally determine a predetermined value for the height of the bright spot formed on the outermost part of the joining material or the tangential direction of the surface of the joining material at the bright spot position at the boundary point of the joining material.

8. In the mounting apparatus of claim 1, The lighting device has multiple light sources that can be individually turned on and off, The control device is configured to change the irradiation position by turning on and off the plurality of light sources.

9. An imaging device directed at a bonding material, which is solder or resin paste, having a specular reflective surface, An illumination device having a light source provided above the joining material, A control device is configured to inspect the amount of coating applied by changing the position of the light source, thereby changing the position of the bright spots which are reflection points of the light emitted from the light source on the surface of the bonding material, and calculating the three-dimensional shape of the bonding material based on a plurality of images obtained by the imaging device capturing the bonding material. Equipped with, The irradiation position of the light source can be changed within the horizontal plane. An inspection apparatus in which the light sources are arranged in different horizontal planes such that the angle of incidence of the light irradiated onto the bonding material changes.

10. A step of loading a substrate into a mounting apparatus comprising: an imaging device directed at a bonding material which is solder or resin paste having a specular reflective surface; and an illumination device having a light source provided above the bonding material; A step of applying the bonding material to the substrate, A step of inspecting the amount of coating applied by changing the irradiation position of the light source to change the position of the bright spots, which are reflection points of the light emitted from the light source, on the surface of the bonding material, and calculating the three-dimensional shape of the bonding material based on a plurality of images obtained by the imaging device capturing the bonding material, A step of attaching an element to the substrate via the bonding material, It has, The irradiation position of the light source can be changed within the horizontal plane. A method for assembling an element in which the light sources are arranged in different horizontal planes such that the angle of incidence of the light irradiated onto the bonding material changes.

11. A step of loading a substrate into a mounting apparatus that includes an imaging device directed at a bonding material which is solder or resin paste, and an illumination device having a light source provided above the bonding material, A step of applying the bonding material to the substrate, A step of inspecting the amount of coating applied by changing the irradiation position of the light source to change the position of the bright spots, which are reflection points of the light emitted from the light source, on the surface of the bonding material, and calculating the three-dimensional shape of the bonding material based on a plurality of images obtained by the imaging device capturing the bonding material, A step of bonding the die to the substrate via the bonding material, It has, The irradiation position of the light source can be changed within the horizontal plane. A method for manufacturing a semiconductor device, wherein the light source is arranged in different horizontal planes such that the angle of incidence of the light irradiated onto the bonding material changes.

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