JP4021351B2 - BONDING LIGHTING DEVICE AND BONDING LIGHTING DEVICE CALIBRATION METHOD - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bonding illumination device and a bonding illumination device calibration method, and more particularly, to a bonding illumination device and a bonding illumination device calibration method for calibrating a change in light quantity of a plurality of light sources.
[0002]
[Prior art]
Generally, in a wire bonder or a die bonder, the position of a device is detected using a camera, and the bonding tool and the device are accurately positioned based on the information to perform bonding. For accurate position detection, it is preferable that the illumination during imaging does not fluctuate. That is, when the light amount of the light source decreases, the S / N ratio of the captured image decreases, and in an extreme case, a necessary signal is buried in noise and cannot be detected. Conversely, when the amount of light from the light source increases, the luminance is saturated and necessary information may be lost. In addition, when the illumination light amount of a part of the imaging range changes, only the luminance of the part changes.For example, when performing position detection by performing normalized correlation processing on an image, the local luminance change The accuracy may be reduced.
[0003]
However, when a plurality of light sources are used to illuminate the object, it is not easy to correct the deterioration of each light source and always keep the illumination during imaging constant. For example, a method of providing a light receiver for detecting the amount of light for each light source is conceivable. However, as the number of light sources increases, the number of light receivers increases, the arrangement space of the light receivers increases, and the apparatus is complicated. It becomes. Furthermore, when some of the light receivers are dirty, the light quantity may not be calibrated correctly.
[0004]
In order to control illumination by a plurality of light sources without increasing the number of light receivers, in Patent Document 1, a point having a high luminance from each image when each light source is individually operated is used as a control point for each light source. Luminance data is used as reference data. And the brightness | luminance of each control point when all the light sources are operated is compared with each reference data, and each light source is controlled according to the difference. That is, it is disclosed that the change in luminance at each control point is mainly due to the change in the corresponding individual light source, and the output of the corresponding individual light source is controlled.
[0005]
In Patent Document 2, illumination light from a plurality of light sources is detected by a single detection means. In this case, the ratio (relation coefficient) that the brightness of each light source contributes to the overall brightness is calculated in advance, the brightness of each light source is calculated from the entire illumination light using the relationship coefficient, and the reference value Control compared to That is, the change in the overall illumination light is considered to be the result that the brightness of each light source changes at the same rate of change, and if the overall illumination light changes K times, the brightness of each light source is also all K times As a change, it is disclosed to control individual light sources.
[0006]
[Patent Document 1]
JP 2002-75668 A
[Patent Document 2]
Japanese Patent Laid-Open No. 11-74090
[0007]
[Problems to be solved by the invention]
As described above, Patent Literature 1 can be applied only when each light source has a control point that can be considered to be mainly illuminated by one light source. Patent Document 2 can be applied only when the brightness of each light source changes at a uniform rate of change. As described above, in the prior art, there is a limitation in controlling illumination by a plurality of light sources without increasing the number of light receivers.
[0008]
An object of the present invention is to solve the problems of the prior art and provide a bonding illumination device and a bonding illumination device calibration method capable of calibrating changes in each light source without increasing the number of light receivers.
[0009]
[Means for Solving the Problems]
1. Principle for determining the amount of light from each light source
First, a method for calculating the light amounts of a plurality of light sources without increasing the number of light receivers will be described. If there is only one light source, if the light quantity L of the light source changes, the bonding part illuminated by the light source is observed with an image pickup device, and the change in luminance B is seen. For example, it is generally considered that the L setting T, for example, the set value of the light source volume, should be increased so as to compensate for the 10% decrease in B.
[0010]
This idea is based on the premise that there is a linear relationship between the luminance B and the light amount L and that there is a certain functional relationship between the light amount L and the light amount setting T. The deterioration of the light amount means that the light amount changes even though the light amount setting T is the same. Therefore, if the degree of deterioration is a deterioration coefficient, the functional form of the functional relationship between the light amount L and the light amount setting T is maintained. As it is, it can be considered that the light amount L changes by the amount multiplied by the deterioration coefficient. For example, assuming that the linear relationship is a linear relationship, the luminance coefficient that links the luminance B and the light amount L is a, the relationship between the light amount L and the light amount setting T is a function f (T), and the light amounts L and f (T) If the deterioration coefficient γ is set between the two, the equation (1) can be expressed.
[Expression 1]
B = a * L = a * [gamma] * f (T) (1)
That is, the change in the light quantity L can be detected by the change in the brightness B. When the brightness B changes even when the setting T is not changed, the deterioration coefficient γ changes, so the brightness B is kept constant. The setting T is changed so as to change the size of f (T).
[0011]
For example, in the simplest case of f (T) = T, equation (1) becomes B = a × γ × T. In the above example in which the brightness B is reduced by 10%, γ = 0.9. Therefore, in order to maintain the luminance B constant, it can be easily derived that the setting T may be increased to 1 / 0.9 = 1.11. Even if f (T) is a general function, the calibration amount of the setting T that compensates for the change in the brightness B can be obtained in the same manner as long as the function form does not change due to the deterioration of the light amount. Thus, when there is one light source, the change in the amount of light can be easily calibrated according to the equation (1).
[0012]
The principle of the present invention resides in the idea of extending the formula (1) to a plurality of luminances and a plurality of light sources without increasing the number of light receivers. Assuming that a linear relationship is established between a plurality of luminances and a plurality of light sources, equation (1) can be expanded to n luminances and m light sources, and can be expressed as equation (2).
[Expression 2]
(B_i) = (A_ij) (L_j(2)
However, 1 ≦ i ≦ n and 1 ≦ j ≦ m. Where (B_i) Is an n-dimensional vertical vector, (a_ij) Is an n-by-m matrix, (L_j) Represents an m-dimensional vertical vector. (A_ij) Is the individual brightness B_iAnd individual light quantity L_jCorresponds to a matrix of a set of luminance coefficients. For example, when n = m = 2, that is, when there are two light sources, the expression (2) is expressed by the following expression (3).
[Equation 3]
B₁= A₁₁L₁+ A₁₂L₂
B₂= A_{twenty one}L₁+ A_{twenty two}L₂              (3)
Where a₁₁Is B₁And L₁Is a luminance coefficient linking₁₂Is B₁And L₂The luminance coefficient that links_{twenty one}Is B₂And L₁The luminance coefficient that links_{twenty two}Is B₂And L₂Is a luminance coefficient. For multiple light sources, each luminance and each light quantity are linked by a luminance coefficient. Assuming that the reflectance of the object to be imaged does not depend on the light quantity of each light source in the range of the light quantity of the light source normally used This is because the above holds.
[0013]
From equation (3), the luminance coefficient a₁₁, A₁₂, A_{twenty one}, A_{twenty two}Is obtained in advance, two luminances B₁, B₂, The simultaneous equations can be solved and the two unknowns L₁, L₂It can be seen that. Similarly, in general, when there are a plurality of k light sources, k × k luminance coefficients are obtained in advance, k luminances are measured, and simultaneous equations are calculated to calculate k unknown light quantities. it can.
[0014]
That is, the principle of obtaining the light quantity of each light source of the present invention is to formulate an expression that connects the brightness and the light quantity by a brightness coefficient, measure a plurality of brightnesses, and solve at least a simultaneous equation equal to the number of light sources to solve each light source. There is a place to ask for the amount of light. In order to realize this principle without increasing the number of light receivers, a calibration area for measuring a plurality of luminances is set in the bonding portion, and a plurality of luminances are detected by a single imaging device. In addition, a luminance coefficient necessary for calculating each light quantity from a plurality of detected luminances is obtained in advance.
[0015]
It should be noted that the principle of obtaining the light quantity of each light source of the present invention can be applied in the same manner as long as the measurement object is not a luminance as long as the quantity is linearly related to the light quantity. It can be understood from the explanation of (3) etc. As the physical quantity that is linearly related to the light quantity, the gradation of R, G, and B data in a color image can be used in addition to the luminance. In addition, for example, a value obtained by performing a certain arithmetic process on a physical quantity that is linearly related to the amount of light, such as a difference in luminance and gradation, can be used.
[0016]
  2. Problem solving means
  A bonding illumination device according to the present invention includes a plurality of light sources capable of changing the amount of light, an imaging device that images a bonding portion illuminated by the plurality of light sources,Prior to calibrating the light intensity setting of each light source, the light intensity was set for each of the plurality of light sources, and the bonding part was imaged.On the imaging data, at least as many calibration areas as the number of light sourcesIn advanceSet and for each calibration areaThatDetect physical quantities that have a linear relationship with light intensity from image dataPrecedingDetection means and a plurality of calibration areasPre-detected aboutEach physical quantity,When detecting each physical quantityMultiple light sourcesAbout presetEach light quantityAnd each physical quantity and each light quantity based onMultiple physical quantity coefficientsIn advanceAskingTheStorage means for storing;In order to calibrate the light intensity setting of each light source, the light quantity is set for each of the plurality of light sources, the bonding part is imaged, and the physical quantity is obtained from the imaging data for each calibration area set in advance on the captured image data. Is stored in advance in the detection means for calibration and the storage means.Using multiple physical quantity coefficients,By calibration detection meansA light amount calculating means for calculating each light amount of the plurality of light sources from the detected plurality of physical quantities;Compare each calculated light quantity with each standard light quantity under the standard lighting conditions determined in advance.eachCalculationCalibration means for calibrating the light amount setting of each light source in accordance with a change in the light amount. The physical quantity is preferably the brightness of the image data. Further, the physical quantity is preferably the gradation of the imaging data.
[0017]
With the above configuration, a plurality of calibration areas equal to at least the number of light sources are set on the imaging data of the bonding unit, and a plurality of physical quantities in the plurality of calibration areas and light quantities of the plurality of light sources are linked in advance. The physical quantity coefficient is obtained and stored. Then, the physical quantity of the imaging data is detected for each calibration area, the light quantities of the light sources are calculated from the detected physical quantities using the stored physical quantity coefficients, and the calculated light quantities The light amount setting of each light source is calibrated in accordance with the change of the light source. Therefore, it is possible to calibrate the change in the amount of light of each light source without requiring a light receiver other than the imaging device. The physical quantity may be anything that has a linear relationship with the light amount of the light source and can be detected from the imaging data. For example, brightness, gradation of R, G, and B data can be used.
[0018]
The bonding lighting device according to the present invention further includes a weighting unit that performs weighting processing on each physical quantity coefficient according to uneven imaging of the illuminated bonding portion, and the light amount calculation means includes each physical quantity coefficient after the weighting process. It is preferable to calculate each light quantity based on the above.
[0019]
When unevenness of imaging called so-called shading occurs due to the arrangement of each light source or the characteristics of the optical system of the imaging device, the physical quantity of the bonding part, for example, the brightness differs depending on where in the imaging range the bonding part is located. The With the above configuration, each physical quantity coefficient is weighted according to the imaging unevenness of the bonding unit. Therefore, by performing weighting that compensates for shading, it is possible to calculate each light amount in accordance with the same reference regardless of the position of the imaging range occupied by the bonding portion.
[0020]
Moreover, the bonding illumination device according to the present invention preferably includes a statistical light amount calculation unit that calculates each light amount by statistical processing when the number of calibration regions exceeds the number of light sources. With the above configuration, the number of calibration regions is set to exceed the number of light sources. Therefore, by using statistical processing, for example, the least square method, the most probable amount of light can be obtained, and the accuracy of illumination calibration control can be further improved.
[0021]
Further, it is preferable that the statistical light quantity calculating means calculates each light quantity again except for data having a large deviation from a probable relationship between the physical quantity and the light quantity by statistical processing.
[0022]
For example, when dust or the like is attached on the calibration area, an accurate value may not be obtained if the light amount of each light source is calculated including the brightness of the calibration area. With the above configuration, the number of calibration areas is set to exceed the number of light sources, the most probable light quantity is obtained by statistical processing, and data that has a large deviation from the most probable relationship is excluded. Each light quantity is calculated. In this way, abnormal data having a large deviation due to the cause of dust adhesion or the like can be excluded, so that the light amount can be calculated more accurately.
[0023]
Further, the bonding illumination device according to the present invention includes a physical quantity averaging means for obtaining an average physical quantity of the imaging data for each calibration region using a plurality of imaging data taken for the same type of bonding portion, The calculating means preferably calculates each light quantity based on each average physical quantity.
[0024]
For example, when the bonding portion is inclined, when a positional deviation occurs, when the quality varies, etc., these may become noise when calculating the amount of light. With the above configuration, an average physical quantity, for example, an average luminance is obtained for the same type of bonding part. Therefore, noise due to bonding portion variations can be reduced, and more accurate light quantity can be calculated.
[0025]
  Moreover, the lighting apparatus for bonding which concerns on this inventionAre a plurality of light sources that can vary the amount of light, an imager that images the bonding unit illuminated by the plurality of light sources, and a light amount setting for each of the light sources prior to calibrating the light amount setting of each light source. The physical quantity that is at least equal to the number of light sources and has a linear relationship with the light quantity has different values for the same light quantity.Includes 2 regionsPreset the calibration area,For each calibration area,From the imaging data,Detect a physical quantity difference that is the difference between physical quantities in each of the two areasBased on the preceding detection means, each physical quantity difference detected in advance for a plurality of calibration regions, and each light quantity preset for a plurality of light sources when detecting each physical quantity difference,Multiple physical quantity coefficients linking each physical quantity difference and each light quantityIn advanceAskingTheMemoryIn order to calibrate the storage means and the light amount setting of each light source, the light amount is set for each of the plurality of light sources, the bonding part is imaged, and each calibration area set in advance on the imaged imaging data, Detected by the calibration detection means using a calibration detection means for detecting a physical quantity difference from the imaged data and a plurality of physical quantity coefficients stored in advance in the storage means.Calculate each light quantity of multiple light sources from multiple physical quantity differencesLight quantity calculation means, compare each calculated light quantity with each standard light quantity under standard illumination conditions determined in advance, and set the light quantity of each light source according to the change of each calculated light quantity from each standard light quantity Calibration means for calibratingIt is characterized by that.
[0026]
In bonding, for example, in the position measurement, the image contrast may be more important than the image brightness. At this time, it is desirable to detect a physical quantity corresponding to the light quantity of each light source that represents the contrast of each calibration area instead of the luminance of each calibration area, and associate this with the light quantity of each light source. For example, the calibration area can be set to include two areas having different luminance coefficients, and the physical quantity representing the contrast can be obtained by the luminance difference between the two areas. In addition to the luminance difference, a gradation difference may be used.
[0027]
With the above configuration, for each calibration area including two areas having different physical quantity coefficients, a physical quantity difference that is a difference between physical quantities in each of the two areas, for example, a luminance difference is detected. Therefore, it can be used to express contrast. Then, a plurality of physical quantity coefficients are obtained and stored in advance as coefficients for connecting the respective physical quantity differences of the plurality of calibration areas and the respective light quantities of the plurality of light sources, and the light quantities of the plurality of light sources are calculated using this. In this way, the light quantity of each light source can be calibrated by paying attention to the change in contrast.
[0028]
It should be noted that the weighting means, the statistical light quantity calculating means, and the physical quantity averaging means for the luminance can be applied individually or in combination when a physical quantity difference is used instead of the physical quantity.
[0029]
  Further, the calibration method of the lighting device for bonding according to the present invention includes an illumination step of illuminating the bonding portion with a plurality of light sources capable of changing the amount of light, an imaging step of imaging the illuminated bonding portion with an imaging device,Prior to calibrating the light intensity setting of each light source, the light intensity was set for each of the plurality of light sources, and the bonding part was imaged.On the imaging data, at least as many calibration areas as the number of light sourcesIn advanceSet and for each calibration areaThatDetect physical quantities that have a linear relationship with light intensity from image dataPrecedingDetection process and multiple calibration areasPre-detected aboutEach physical quantity,When detecting each physical quantityMultiple light sourcesAbout presetEach light quantityAnd each physical quantity and each light quantity based onMultiple physical quantity coefficientsIn advanceAskingTheA storage step for storing;In order to calibrate the light intensity setting of each light source, the light quantity is set for each of the plurality of light sources, the bonding part is imaged, and the physical quantity is obtained from the imaging data for each calibration area set in advance on the captured image data. Are detected in advance and stored in advance in the storage means.Using multiple physical quantity coefficients,By calibration detection meansA light amount calculation step of calculating each light amount of the plurality of light sources from the detected plurality of physical quantities, and the calculatedCompare each calculated light quantity with each standard light quantity under the standard lighting conditions determined in advance.eachCalculationA calibration step of calibrating the light amount setting of each light source in accordance with a change in the light amount.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, an illumination device used for a wire bonder will be described. However, a device for illuminating a chip or the like in a face down bonder, a die bonder or the like, or a chip such as an LSI or a circuit board for visual inspection before and after a bonding operation, etc. It may be a device for illuminating. In addition, a case where two types of illumination, that is, two types of light sources are used will be described. In addition, a plurality of the same type of illumination may be used. As the physical quantity having a linear relationship with the light amount of the light source, the gradation (brightness) in the black and white image data is used. However, as described above, for example, it may be the gradation of R, G, B in a color image. Moreover, although the imaging device for detecting the brightness | luminance of the illuminated target object is demonstrated as what is imaged using the reflected light from a target object, you may image using the transmitted light from a target object.
[0031]
FIG. 1 is a block diagram of a bonding lighting device 10. In this example, a portion provided as an apparatus for illuminating a chip to be bonded or a circuit board in the wire bonder is shown. Elements not related to the wire bonder illumination are not shown. The bonding illumination device 10 includes an imaging device 14 that images the object 12 such as a chip, two lights 20 a and 20 b that illuminate the object 12, and an illumination control unit 40. The imaging device 14 and the two illuminations 20a and 20b are connected to the imaging I / F 44 and the illumination I / Fs 46a and 46b of the illumination control unit 40, respectively.
[0032]
The imaging device 14 is a camera that images the object 12 such as a chip or a circuit board. For example, a CCD (Charge Coupled Device) camera in which a plurality of imaging elements are two-dimensionally arranged can be used. The image pickup device 14 picks up an image centering on a bonding portion such as a bonding pad on a chip or a bonding lead of a circuit board necessary for bonding positioning. The imaged data is associated with the imaging position as, for example, 256 gradation digital data, and is sent to the imaging I / F 44 of the illumination control unit 40 via a signal line. Note that the bonding unit can be moved to the imaging range of the imaging device 14 by an object moving device (not shown).
[0033]
The two lights 20a and 20b are variable light amount light sources that are arranged at an intermediate position between the image pickup device 14 and the target object 12 and can adjust the light amount by setting. FIG. 1 shows two types of illumination. The first illumination 20a is an epi-illumination device including a halogen lamp 22 and a half mirror 24, and the second illumination 20b is a ring illumination device in which a plurality of LEDs (Light Emission Diode) are arranged in a ring shape. The illuminated object 12 can be imaged by the imaging device 14 through the half mirror 24 and the opening at the center of the ring.
[0034]
The amount of light of the two lights 20a and 20b can be varied by setting the power supplied to the halogen lamp 22 and the plurality of LEDs. The power can be set by setting the voltage applied to the halogen lamp 22 or the plurality of LEDs as a digital value, or the lighting time can be set as a digital value by pulse width control. The ratio between the lighting time and the extinguishing time may be set as a digital value. Data for setting the amount of light is sent from the illumination I / Fs 46a and 46b of the illumination control unit 40 to the respective illuminations 20a and 20b via signal lines.
[0035]
The illumination control unit 40 has a function of controlling the amount of light of each of the illuminations 20a and 20b based on data received from the imaging device 14, and can be configured by a general computer. Specifically, the imaging data is acquired from the imaging I / F 44, and processing such as calculating the light amount of each of the illuminations 20a and 20b based on the imaging data and a plurality of luminance coefficient data described later is performed. / F 46a, 46b has a function of outputting control data for calibrating the light amount setting of each of the lights 20a, 20b. Software can be used to perform processing based on imaging data and luminance coefficient data, and predetermined processing can be performed by executing a corresponding processing program. A part of the processing can be executed by hardware.
[0036]
The illumination control unit 40 includes a CPU 42, an imaging I / F 44 connected to the imaging device 14, two illumination I / Fs 46a and 46b connected to two illuminations, an input unit 48 such as a keyboard, an output unit 50 such as a display, An external storage device 52 that stores luminance coefficient data and the like is included, and these are connected to each other via an internal bus.
[0037]
The image processing module 60 and below in the CPU 40 has a function of performing processing for controlling the light amounts of the respective illuminations 20a and 20b based on the imaging data and the luminance coefficient data. The function of each processing module will be described in detail below using a flowchart of processing for obtaining and storing a luminance coefficient, a flowchart of processing for calculating each light quantity using the luminance coefficient, and the like.
[0038]
FIG. 2 is a flowchart showing a procedure for calculating the luminance coefficient data and storing them in the luminance coefficient file 80 of the external storage device 52.
[0039]
As described above, the luminance coefficient is a coefficient that combines the luminance and the light amount. When there are two pieces of illumination, Expression (3) can be used.
[Equation 3]
B₁= A₁₁L₁+ A₁₂L₂
B₂= A_{twenty one}L₁+ A_{twenty two}L₂              (3)
Where L₁Is the light quantity of the first illumination 20a, L₂Is the amount of light of the second illumination 20b, and B₁, B₂Is the brightness of each of the two calibration areas set on the imaging data, a₁₁, A₁₂, A_{twenty one}, A_{twenty two}Is each brightness B₁, B₂And each light quantity L₁, L₂Is a luminance coefficient.
[0040]
The four luminance coefficients can be calculated and stored one by one according to the flowchart of FIG. As an example, the luminance B in the first calibration area among the two calibration areas set on the imaging data₁And the light quantity L of the first illumination 20a₁The luminance coefficient a₁₁The calculation procedure will be described.
[0041]
First, the standard illumination 20a is prepared. The illumination in the standard state is preferably one that does not deteriorate the light source and operates stably, for example. That is, the degradation coefficient γ can be 1. The light quantity L of the illumination 20a is equal to the light quantity setting T multiplied by the deterioration coefficient γ. Next, the light amount setting T of the first illumination in the standard state₁T appropriately₁= T1 (S10). For example, t1 = 1 msec is set assuming that the light amount is set by the lighting time. The light amount setting can be performed by inputting data t1 from the input unit 48 and controlling the light amount of the first illumination 20a via the illumination I / F 46a. Further, when the first illumination 20a has a manual setting knob and the set value is sent as data to the illumination control unit 40 via the illumination I / F 46a, the manual knob is appropriately turned to set the set value as t1. May be.
[0042]
Next, the light intensity setting T₁The chip is imaged by the imaging device 14 under = t1 (S12). The imaged data is sent to the image processing module 60 of the CPU 42 through the imaging I / F 44 as gradation data associated with position data within the imaging range.
[0043]
The image processing module 60 has a function of processing the received imaging data and specifying the positions of the first calibration area and the second calibration area within the imaging range. The first calibration area and the second calibration area are two luminance detection areas set on the imaging data in order to detect the luminance of light guided from the illuminations 20a and 20b via the chip.
[0044]
FIG. 3 is a diagram illustrating how the first calibration area and the second calibration area are set. In FIG. 3, a part of the chip 102, in particular, a plurality of bonding pads 104 to be wire-bonded are captured in the imaging range 100. In the two luminance detection regions, for example, the first calibration region 110 can be set in a slightly dark marker portion of the corner portion of the chip 102, and the second calibration region 112 can be set in a portion between the bonding pads. In other areas, a calibration area may be set by selecting an area useful for positioning of wire bonding.
[0045]
Luminance coefficient a₁₁To obtain the brightness of the imaging data in the first calibration area. The first calibration area can be specified by specifying the position coordinates of each pixel constituting the first calibration area 110 in the imaging range 100. The position coordinates of each pixel constituting the specified first calibration area 110 and each gradation data thereof are sent to the luminance detection module 62.
[0046]
The luminance detection module 62 determines the luminance B of the first calibration area based on the specified gradation data over the first calibration area 110.₁It has a function to detect. For example, when the number of pixels in the first calibration area is 50 × 50 = 250, the gradation data of each pixel may be added, and the total gradation value may be used as the luminance of the first calibration area as it is. Further, the total data may be divided by the total number of pixels, and the gradation value per pixel may be used as the luminance of the first calibration area. Here, the gradation value per pixel is represented by luminance B₁For example, B₁= B1 = 15 (gradation) is detected (S14).
[0047]
  The above light quantity setting (S10), imaging (S12), and luminance detection (S14) are all performed.Pair andThen, the light amount setting T is reached until the predetermined number is reached.₁Is repeated (S16). The greater the number of settings, the higher the accuracy of calculating the luminance coefficient, but it takes time, so it can be determined based on these factors. For example, set the number5As the light quantity setting T₁TheIn addition to the previous t1,T2 = 3 msec, t3 = 5 msec, t4 = 8 msec, t5 = 10 msec are sequentially changed, and the respective luminances b2, b3, b4, b5 are detected.
[0048]
When the set number of luminances is detected, a luminance coefficient is obtained from the relationship between the light amount setting and the detected luminance (S18). An example of how to obtain the luminance coefficient is shown in FIG. 4 shows the light amount setting T on the horizontal axis.₁, Luminance B on the vertical axis₁And set the light intensity T₁Luminance B detected when changing₁FIG. Since the first illumination 20a in the standard state is used as described above, the light amount L of the first illumination 20a.₁= T₁And can. Therefore, the luminance coefficient a₁₁= B₁/ L₁= B₁/ T₁From the slope of the straight line shown in FIG.₁₁Can be requested.
[0049]
Similarly, other luminance coefficients a₁₂, A_{twenty one}, A_{twenty two}Can also be sought. The obtained luminance coefficients are stored in the luminance coefficient file 80 of the external storage device 52 (S20). Since the luminance coefficient depends on the reflectance of the calibration area and the like, for example, if the chip illuminated to obtain the luminance coefficient is different, the value of the luminance coefficient is different, and even if the setting of the calibration area is different even on the same chip. This is the value of the luminance coefficient. Therefore, the luminance coefficient is stored in association with the object such as a chip used for obtaining the luminance coefficient, the contents of the calibration area, and the like.
[0050]
FIG. 5 is a flowchart showing a procedure for calculating each light amount using the luminance coefficient and calibrating the light amount setting of each light source. In this case, each illumination is not always maintained in the standard state, and therefore, the deterioration coefficient γ = 1 is not always satisfied. In other words, the light quantity L may change even though the light quantity setting T of each light source is not changed, and FIG. 5 shows a procedure for calibrating the change in the light quantity.
[0051]
Therefore, first, an optimum lighting condition is determined. Optimum illumination conditions are set by adjusting the light amount settings of the respective illuminations 20a and 20b so that the positions of the bonding pads of the chip and the bonding leads of the circuit board can be clearly recognized on the imaging data. The light quantity L of the first illumination 20a under the optimal illumination conditions_{1 (0)}And the amount of light L of the second illumination_{2 (0)}Is a reference for determining the change in the amount of light of each illumination, and is preferably stored in, for example, the external storage device 52 or the like. As described above, when the optimum illumination condition is determined using illumination in a state without deterioration, the optimum light amount L_{1 (0)}, L_{2 (0)}Is the optimum light intensity setting T_{1 (0)}, T_{2 (0)}Can be expressed as
[0052]
In FIG. 5, first, the position of the chip to be the object 12 is adjusted and set so as to be within a predetermined imaging range of the imaging device 14, and each illumination 20a, 20b is operated to illuminate (S30). Next, an image is taken by the imager 14 (S32). The imaged data is sent to the image processing module 60, and the first calibration area 110 and the second calibration area 112 are specified on the imaged data in the same procedure as described after the step S12 in FIG. . For identification, the identification data of the chip of the object 12 is input from the input unit 48, and the data related to the calibration area stored in the external storage device 52, for example, can be read and used accordingly.
[0053]
The specified data of the first calibration area 110 and the second calibration area 112, for example, the position coordinates of each pixel constituting each calibration area and its gradation data are sent to the luminance detection module 62. The luminance detection module 62 performs the luminance B of the first calibration area 110 by the same procedure as described in the step S14 in FIG.₁And the brightness B of the second calibration area 112₂Are detected (S34). Each detected brightness B₁, B₂Is sent to the light quantity calculation module 64.
[0054]
The light quantity calculation module 64 detects each luminance B detected according to the above equation (3).₁, B₂And each luminance coefficient a₁₁, A₁₂, A_{twenty one}, A_{twenty two}And each light quantity L₁, L₂It has the function to calculate. Specifically, in the two simultaneous equations of Equation (3), each luminance B₁, B₂And each light quantity L is an unknown number₁, L₂Is calculated (S36). Each luminance coefficient a₁₁, A₁₂, A_{twenty one}, A_{twenty two}Reads out from the external storage device 52 each luminance coefficient of the same object and calibration area that have been subjected to the luminance detection (S34) and uses them.
[0055]
Calculated light quantity L₁, L₂Are sent to the calibration module 66. The calibration module 66 has a function of comparing each light quantity calculated with the light quantity under the optimum illumination condition, and calibrating the light quantity setting of each illumination according to the change in each light quantity. The calibrated light amount setting data is sent to the respective illuminations 20a and 20b via the illumination I / Fs 46a and 46b, and each light amount setting is calibrated so that the light amount of each illumination becomes the light amount in the optimum illumination condition (S38). ). For example, the light amount L in the optimal illumination condition of the first illumination_{1 (0)}Is L_{1 (0)}= 30 msec, calculated light quantity L₁However, if it is assumed that the deterioration coefficient γ is 1, it corresponds to the light amount setting of 27 msec, and the deterioration coefficient γ at this time is 27/30 = 0.9. In other words, the light amount is reduced by 10% even though the light amount setting remains 30 msec. Therefore, the light amount setting is increased in accordance with this light amount change. For example, an instruction to compensate for a decrease of 10% is given to the illumination 20a via the illumination I / F 46a with respect to the light amount setting. The light amount setting is similarly calibrated for the second illumination 20b.
[0056]
In this way, a formula that links the brightness and the light quantity with the brightness coefficient is established, a plurality of brightnesses are measured, and at least the simultaneous equations equal to the number of lights are solved to obtain the light quantity of each illumination, and according to the change of each light quantity The light quantity setting of each illumination can be calibrated.
[0057]
FIG. 6 is a diagram illustrating an example in which the calibration area is set across areas having different reflectances. FIG. 6 shows the same imaging range as FIG. 3, and the calibration area 114 is set across a slightly dark marker part and a slightly brighter part outside the corner part of the chip 102. Therefore, the brightness of the calibration region 114 changes along the x direction in FIG. This situation is shown in FIG. 7 where the vertical axis represents luminance and the horizontal axis represents the position in the x direction.
[0058]
The luminance difference ΔB, which is the difference in luminance between the two regions in FIG. 7, can be taken as a physical quantity that is linearly related to the amount of light. The brightness difference ΔB can be related to a so-called amount of contrast. Therefore, if the amount of light of each illumination is calibrated based on the change in the brightness difference ΔB, the illumination device can maintain a constant contrast. In this case, the process of calculating and storing the luminance difference coefficient using the coefficient that links the luminance difference ΔB and the light quantity L as the luminance difference coefficient and calculating each light quantity using the luminance difference coefficient has been described with reference to FIGS. The content can be processed by replacing the luminance with a luminance difference.
[0059]
That is, the brightness difference ΔB can be detected by the brightness difference detection module 68 based on the data of the calibration area 114 specified by the image processing module 60 of the CPU 42. That is, the position coordinates of each pixel constituting the specified calibration area 114 and each gradation data thereof are sent to the luminance difference detection module 68, where the luminance difference ΔB, which is the difference in luminance between the two areas in each gradation data, is obtained. Detected. Using this luminance difference ΔB, the necessary luminance difference coefficient can be obtained by proceeding with processing by replacing the luminance with the luminance difference in the procedure shown in FIG. 2, and the obtained luminance difference coefficient is the luminance of the external storage device 52. The difference coefficient file 82 can be stored.
[0060]
Further, by using this luminance difference ΔB, the light intensity can be calculated by replacing the luminance with the luminance difference in the procedure shown in FIG. 5, and the light amount setting of each illumination can be performed according to the change of each light amount. Can be calibrated.
[0061]
FIG. 8 is a diagram illustrating a so-called shading state in which imaging unevenness caused by the arrangement of each light source and the characteristics of the optical system of the image pickup device and the like. FIG. 8 shows data captured by using, for example, white paper instead of the chip and operating only one of the two lights. When the image unevenness occurs in this manner, the image of the calibration area is picked up with different brightness depending on where the calibration area is located in the imaging range. Therefore, weighting can be performed according to the magnitude of the influence of shading to compensate for the influence of shading. That is, as shown in FIG. 8, imaging data for detecting only shading is collected by imaging using a blank sheet or the like, and an average gradation is obtained for each region having a different influence of shading. Based on the average gradation of shading thus obtained, the weighting coefficients C0, C1, C2, and C3 can be determined so as to compensate for unevenness in the average gradation. By using this weighting coefficient, the luminance coefficient or the luminance difference coefficient can be weighted to reduce the influence of shading.
[0062]
In the above description, two luminances are used to calculate the respective light amounts of the two illuminations. That is, generally speaking, each light quantity of each illumination can be calculated by using the same number of luminances as the number of illuminations. Here, if the number of luminances exceeding the number of illuminations is used, statistical processing can be performed for the calculation of each light amount, and the accuracy of illumination calibration control can be further improved. Also, if abnormal data is removed by statistical processing, for example, it is possible to perform more accurate illumination calibration control by excluding dust or the like that is attached to the chip or optical system and causing noise. it can.
[0063]
In FIG. 9, it is assumed that there is one illumination for easy explanation, and the light quantity L of the first illumination is obtained when five calibration areas are set for the illumination and five luminances are detected.₁In order to calculate the luminance coefficient on the horizontal axis and the luminance B on the vertical axis. In this example, the luminance coefficient is a₁, A₂, A_Three, A_Four, A_FiveThere are five brightness B corresponding to this.₁, B₂, B_Three, B_Four, B_FiveIs detected. The light quantity L can also be obtained by dividing each luminance B by the corresponding luminance coefficient. However, in the example of FIG. 9, the least square method is applied to the detected five luminance data. . That is, since there is a relationship of B = aL, a solid line is obtained by drawing the most probable L = B / a line based on the five luminance data by the least square method. In this way, the most probable value obtained by statistical processing can be used as the amount of light. Even if there are a plurality of illuminations, the same statistical processing is possible, and the expansion is easy.
[0064]
Furthermore, it is possible to obtain a more accurate light quantity by removing data with a large deviation from the most probable solid line. In this example, from the most likely straight line, B_FiveThis data is excluded because the data of B as abnormal data_FiveThe broken line is obtained by redrawing the straight line L = B / a from the remaining four luminance data by the least square method. In this way, the amount of light can be calculated based on the data from which abnormal data is removed, and more accurate illumination calibration control can be performed.
[0065]
In the above description, each light amount is calculated based on one imaged data. However, the same chip or the same kind of chip is imaged a plurality of times, and the luminance of the calibration area is averaged from these images, and the average is obtained. The respective light amounts may be calculated based on the luminance data thus obtained. By doing so, it is possible to reduce the influence of the inclination or deviation of the set position of the chip or the like or the variation in quality.
[0066]
In the above description, the luminance coefficient is obtained by illuminating the bonding part of the chip. However, the object other than the chip is illuminated, and a plurality of calibration areas are set on the imaging data to obtain the luminance coefficient of the object. Also good. For example, a standard calibration sheet may be used, set in a region where illumination for bonding is performed, a field of view for imaging is imaged, and a luminance coefficient may be obtained from the imaging data. The luminance coefficient obtained in this way can be treated as a luminance coefficient that can be compared with the same standard by standardizing the bonding portion of the chip. For example, the calibration of the light intensity setting of each light source is always performed according to the same standard by detecting the brightness of each calibration area using this standard calibration sheet before or after the bonding work is completed, or at regular inspections. It can be performed.
[0067]
【The invention's effect】
According to the bonding illumination device and the bonding illumination device calibration method according to the present invention, it is possible to calibrate the change in the light amount of each light source without increasing the number of light receivers.
[Brief description of the drawings]
FIG. 1 is a block diagram of a bonding illumination device according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a procedure for calculating luminance coefficient data and storing them in the embodiment according to the present invention.
FIG. 3 is a diagram showing how a calibration area is set in the embodiment according to the present invention.
FIG. 4 is a diagram showing how a luminance coefficient is obtained in the embodiment according to the present invention.
FIG. 5 is a flowchart showing a procedure for calculating each light amount using a luminance coefficient and calibrating the light amount setting of each light source in the embodiment according to the present invention.
FIG. 6 is a diagram showing another example of setting a calibration region in the embodiment according to the present invention.
FIG. 7 is a diagram for explaining a luminance difference in the embodiment according to the invention.
FIG. 8 is a diagram showing imaging unevenness, so-called shading.
FIG. 9 is a diagram for explaining how the amount of light is obtained by statistical processing in the embodiment according to the present invention.
[Explanation of symbols]
10 Lighting equipment for bonding
12 Object
14 Imager
20a, 20b Illumination (light source)
40 Lighting control unit
42 CPU
44 Imaging I / F
46a, 46b Illumination I / F
48 Input section
50 output section
52 External storage
60 Image processing module
62 Luminance detection module
64 Light quantity calculation module
66 Calibration module
68 Luminance difference detection module
80 luminance coefficient file
82 luminance difference coefficient file
100 imaging range
110, 112, 114 Calibration area

Claims (9)

A plurality of light sources capable of varying the amount of light;
An imaging device for imaging a bonding portion illuminated by a plurality of light sources;
Prior to calibrating the light quantity setting of each light source, the light quantity is set for each of the plurality of light sources, the bonding part is imaged , and at least the number of calibration areas equal to the number of light sources is set in advance on the captured image data. A pre- detection means for detecting a physical quantity having a linear relationship with the light amount from the imaging data for each calibration area;
Based on each physical quantity detected in advance for a plurality of calibration regions and each light quantity preset for each of the plurality of light sources when detecting each physical quantity , a plurality of physical quantity coefficients that associate each physical quantity with each light quantity are preliminarily set. Storage means for seeking and storing;
In order to calibrate the light intensity setting of each light source, the light quantity is set for each of the plurality of light sources, the bonding part is imaged, and the physical quantity is obtained from the imaging data for each calibration area set in advance on the captured image data. Calibration detecting means for detecting each of
A light quantity calculating means for calculating each light quantity of the plurality of light sources from a plurality of physical quantities detected by the calibration detecting means using a plurality of physical quantity coefficients stored in advance in the storage means;
A calibration unit that compares each calculated light quantity with each standard light quantity under a predetermined standard illumination condition and calibrates the light quantity setting of each light source according to the change in each calculated light quantity from each standard light quantity When,
A bonding illumination device comprising:   The lighting device according to claim 1, wherein the physical quantity is a luminance of the image data.   The lighting device according to claim 1, wherein the physical quantity is a gradation of the imaging data. The lighting device according to claim 1.
In accordance with imaging unevenness of the illuminated bonding part, the weighting means for performing weighting processing on each physical quantity coefficient,
The light amount calculating means calculates each light amount based on each physical quantity coefficient after the weighting process. The lighting device according to claim 1.
A bonding illumination device comprising: a statistical light amount calculating means for calculating each light amount by statistical processing when the number of calibration regions exceeds the number of light sources. The lighting device according to claim 5.
The lighting apparatus for bonding is characterized in that the statistical light quantity calculation means further calculates each light quantity again except for data having a large deviation from a probable relationship between the physical quantity and the light quantity by statistical processing. The lighting device according to claim 1.
Using a plurality of imaging data imaged for the same type of bonding unit, a physical quantity averaging means for obtaining an average physical quantity of imaging data for each calibration region,
The light amount calculating means calculates each light amount based on each average physical quantity. A plurality of light sources capable of varying the amount of light;
An imaging device for imaging a bonding portion illuminated by a plurality of light sources;
Prior to calibrating the light amount setting of each light source, the light amount is set for each of the plurality of light sources and the bonding portion is imaged.On the captured image data, there are at least a number of calibration regions equal to the number of light sources, A calibration area including two areas in which the physical quantity having a linear relationship with the light quantity is different from each other with respect to the same light quantity is set in advance, and for each calibration area, the difference between the physical quantities in each of the two areas is obtained from the imaging data. Preceding detection means for detecting a certain physical quantity difference ;
A plurality of physical quantities linking each physical quantity difference and each light quantity based on each physical quantity difference detected in advance for a plurality of calibration areas and each light quantity set in advance for a plurality of light sources when detecting each physical quantity difference a storage unit that previously obtained and stored coefficients,
In order to calibrate the light intensity setting of each light source, the light quantity is set for each of the plurality of light sources, the bonding part is imaged, and the physical quantity is obtained from the imaging data for each calibration area set in advance on the captured image data. Calibration detecting means for detecting each difference,
A plurality of light quantity calculation means for calculating light quantities of a plurality of light sources from a plurality of physical quantity differences detected by the calibration detection means using a plurality of physical quantity coefficients stored in advance in the storage means;
A calibration unit that compares each calculated light quantity with each standard light quantity under a predetermined standard illumination condition and calibrates the light quantity setting of each light source according to the change in each calculated light quantity from each standard light quantity When,
Bonding lighting device according to claim Rukoto equipped with. An illumination process for illuminating the bonding portion with a plurality of light sources capable of varying the amount of light;
An imaging step of imaging the illuminated bonding portion with an imaging device;
Prior to calibrating the light quantity setting of each light source, the light quantity is set for each of the plurality of light sources, the bonding part is imaged , and at least the number of calibration areas equal to the number of light sources is set in advance on the captured image data. A pre- detection step for detecting a physical quantity having a linear relationship with the amount of light from the imaging data for each calibration area;
Based on each physical quantity detected in advance for a plurality of calibration regions and each light quantity preset for each of the plurality of light sources when detecting each physical quantity , a plurality of physical quantity coefficients that associate each physical quantity with each light quantity are preliminarily set. A memory step for seeking and storing;
In order to calibrate the light intensity setting of each light source, the light quantity is set for each of the plurality of light sources, the bonding part is imaged, and the physical quantity is obtained from the imaging data for each calibration area set in advance on the captured image data. A detection step for calibration for detecting each of
A light quantity calculation step of calculating each light quantity of a plurality of light sources from a plurality of physical quantities detected by the calibration detection means using a plurality of physical quantity coefficients stored in advance in the storage means ;
A calibration process in which each calculated light quantity is compared with each standard light quantity under a predetermined standard illumination condition, and the light quantity setting of each light source is calibrated according to the change in each calculated light quantity from each standard light quantity When,
A method of calibrating a lighting device for bonding, comprising:

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