JPH11241916A - Height measuring method, height data processing method, and height measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a height measuring method significantly improve in processing cycle time (tact time), thus allowing precise height measurement. SOLUTION: The height of a cream solder part printed on a wiring board is measured by light-section method. A first line beam is projected to a flat part near the cream solder to take its image 112. A second line beam is successively projected to the cream solder part to take its images 113a, 113b. On the basis of the height of the flat part determined from the first line beam image 112, the height of the cream solder part 113a is determined. According to this structure, since the height data of the cream solder part 113a is determined on the basis of the height data of the flat part 112 different from the flat part 113b having the cream solder formed thereon, it is not required to find the height data of the flat part 113b prior to the printing of the cream solder, and the processing cycle time can be remarkably improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a height measuring method, a height data processing method, and a height measuring device, and more particularly, to a fine solder paste printed by a cream solder printing machine used in a surface mounting system. The present invention relates to a height measuring method, a height data processing method, and a height measuring device for measuring a height.

[0002]

2. Description of the Related Art Conventionally, as a device for recognizing a three-dimensional shape and measuring a height, a three-dimensional recognition device using a light section method has been known. Fig. 1 shows a three-dimensional recognition device using this light-section method.
It is shown in FIG. Line light 122 from a line light generator 121, which is a light source, is projected at a predetermined angle from obliquely above the DUT 123, and an image formed along the surface shape formed on the surface of the DUT 123 is vertical. Photographed by the CCD camera 124 from above. The image taken by the CCD camera 124 is CC
The data is A / D converted by the D camera controller 125 and captured by the image capturing unit 126. Then, the captured data is converted into three-dimensional coordinates of the device 123 by the coordinate calculator 127.

In a cream solder height measuring apparatus which is used by being incorporated in a cream solder printing machine, a portion (measurement unit) 128 surrounded by a dotted line in FIG. 14 is incorporated in an XY moving gantry (XY moving mechanism). Used. First, when the wiring board for printing is carried into the cream solder printing machine, after the positioning of the wiring board and the stencil is completed,
The measurement unit 128 is moved by the XY moving gantry from the initial expected evacuation position to the target measurement position. Then, the measurement unit converts the image of the line light formed on the pad surface (resist surface) on the wiring substrate, which is the object to be measured, into CC.
After the image is taken by the D camera 124, it is moved and evacuated again to the first expected evacuation position. Next, cream solder is printed on the pad surface of the wiring board. After the printing on the pad surface of the wiring board is completed, the measuring unit 128 is again moved to the target measuring position by the XY moving gantry, and the image of the line light formed along the shape of the cream solder is transferred to the CCD camera 124. And then re-evacuate to the first expected escape position again.

From the above image data, the coordinates of the center of gravity of the pad surface of the wiring board in the height direction and the coordinates of the center of gravity of the cream solder portion in the height direction are calculated. Then, the subtraction between the coordinates of the center of gravity of the pad surface of the wiring board in the height direction and the coordinates of the center of gravity of the cream solder portion in the height direction is used to calculate the height of the cream solder portion after printing with reference to the pad surface of the wiring board. calculate. Then, the average height of the cream solder portion over each pad surface is calculated.

[0005] In order to obtain a three-dimensional shape, a plurality of data at different light-cut positions are required. For example, the length is 2mm
It is assumed that light cutting is performed at a pitch of 50 μm in order to obtain a three-dimensional shape of the cream solder printed on the pad. In this case, before printing the cream solder, the image of the line light formed on the pad surface of the wiring board is imaged 40 times by the CCD camera while changing the light cutting position. Further, after printing the cream solder, it is necessary to image the line light image formed along the shape of the cream solder 40 times while changing the light cutting position by the CCD camera. Therefore, CCD
The total number of times of imaging by the camera is 80 times. Similarly,
The total number of minute movements of the measurement unit is also 80.

[0006]

However, in a cream solder height measuring device that is used by being incorporated in a conventional cream solder printing machine, an image of a line light before printing and an image of a line light after printing are used. Must be imaged with a CCD camera to calculate the height of the cream solder. For this reason, there has been a problem that the tact time is lengthened and the performance of the entire semiconductor surface mounting system is reduced.

In addition, a heavy measuring unit equipped with a CCD camera must be moved to minutely change the position of light cutting. For an XY moving gantry, a skip function to a target measuring position is provided. In addition, there is a problem that the servo system for driving the XY movement gantry must be provided with two functions, that is, a minute movement at a measurement target position.

Accordingly, the present invention has been made to solve such a problem, and a height measuring method and a height data capable of measuring an accurate height by greatly improving a tact time. It is an object to provide a processing method and a height measuring device.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method for projecting line light onto an object to be measured having a projection projecting from a flat portion, and a flat portion cut by the line light; In a height measuring method for imaging a protrusion and measuring the height of the protrusion from a flat portion by a light cutting method, a first line light is projected on a flat portion near the protrusion to capture an image of the image. Projecting the second line light onto the protrusion, capturing an image of the second line light, and setting the height of the protrusion obtained from the image of the second line light to the height of the flat portion obtained from the image of the first line light. The calculation is performed based on the distance.

In such a configuration, the height data of the protruding object is calculated based on the height data of the flat portion of the object to be measured on which the protruding object has already been formed. When it is not necessary to obtain the height data of the flat part of the flat part and it is necessary to measure the height of the protrusion every time a protrusion is formed on the flat part, for example, printing cream solder on the wiring board, cream The tact time can be significantly improved when the height of the solder must be measured.

Further, in the height data processing of the present invention, since the gradation data of the imaged pixel is binarized after being subjected to the flattening processing, stable height data can be obtained. In addition, when a blank line is generated as a result of performing a filtering process on the binarized data, the data is embedded in the blank line according to the array of the binarized data in the preceding and succeeding lines. Height data is required.

Further, in the present invention, a line light is projected onto an object to be measured having a protrusion projecting from the flat portion, and the flat portion cut off by the line light and the protrusion are imaged, and the flat portion is cut by a light cutting method. A height measuring device for measuring the height of a projecting object from the light source, the light projecting device projecting first and second line lights to a flat portion near the projecting object and the projecting object, respectively; Means for capturing an image of the flat part and the protruding object in the vicinity of the projecting object on which the line light is projected, and processing the image of the flat part and the protruding object near the projecting object by the first and second line lights. A configuration having means for calculating the height of the flat portion and the projecting object, and means for calculating the height of the projecting object based on the height of the flat portion near the projecting object is also adopted.
In such a configuration, the same operation and effect as described above can be obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

[Basic Configuration] FIG. 1 is a basic configuration diagram of main optical components of a three-dimensional measuring apparatus showing an embodiment of the present invention, and FIG. 2 is a side view thereof. In each figure, the reference numeral 1 denotes a laser diode as a laser light source.
The laser light emitted from the laser diode 1 is converted by the collimator lens 2 into a parallel light beam 1a parallel to the optical center axis. This laser parallel light beam 1a enters a light projecting unit 7 in which a focus lens 3, a light projecting mirror 4, and a line generator lens 5 are incorporated. The laser beam is narrowed down to a spot light by the focus lens 3 in the light projecting unit 7, reflected by the light projecting mirror 4 at an angle of 45 degrees with respect to the vertical axis (Z direction), and is reflected by the line generator lens 5. 14 to 20 μm in width,
A line light 9 having a length of 10 mm is formed, and the line light 9 is formed in the X direction on the DUT (cream solder or a wiring board on which it is printed) 11.

The scattered reflected light from the DUT 11 is reflected on the optical axis 6.
6.4 mm × 4.8 arranged so that a is the vertical axis
The image is picked up by a non-interlaced CCD camera 6 having a mm visual field. The light projecting unit 7 is attached to a shaft 8a of a linear motor 8, and the linear motor 8 performs a linear motion with a stroke of about 10 mm in the Y direction, so that the linear Luminous flux 1
Reciprocate in parallel with a. The movement of the light projecting unit 7 causes the line light 9 to move in a direction perpendicular to the X direction in which the line light extends.

[Circuit Configuration (Data Acquisition)] FIG. 3 is a block diagram showing a circuit configuration for acquiring image data of an object to be measured in a three-dimensional measuring apparatus. In the figure, a linear motor drive commander 31 receives a start signal from a CPU 44, outputs a linear motor drive command pulse train to a linear motor driver 32, and sets the linear motor 8 to 1
Move 0.25 μm per pulse. The linear motor drive commander 31 simultaneously sends forward / reverse signals to an LD (laser diode) on / CCD trigger timing decoder (hereinafter referred to as a timing decoder) 35, and the linear motor 8 moves in either the forward or reverse direction. Let them know.

The linear motor driver 32 drives the linear motor in response to the command pulse train, and adjusts the supply voltage to the linear motor 8 in response to the signal indicating the actual position from the position encoder 8b built in the linear motor 8. Feedback control of the position of the linear motor.

The position counter 34 has an A-phase signal having a phase difference of 90 degrees by the position encoder 8b of the linear motor 8,
Upon receiving the B-phase signal, a position signal indicating the position of the linear motor 8 is output as digital data. The position counter 34
Is reset by an origin reset signal from the position encoder 8b.

The timing decoder 35 receives the position data from the position counter 34 and outputs an LD-on timing signal (160 μm pitch). In response to the rise of this signal, the one-shot multivibrator (M
S) 46 outputs an LD ON pulse having a width of 2 ms to the laser diode driver 36 to turn on the laser diode 1 in a pulsed manner. The laser diode 1 has a built-in light amount monitor photodiode (not shown), and the light amount of the laser diode 1 is controlled to be constant.

Note that since the linear motor 8 is moving even while the LD is on, the line light position is shifted depending on the moving direction, and a half pitch (in the embodiment, 80 μm In order to shift, the forward / reverse direction signal is input from the linear motor drive commander 31 as described above.

The position latch 37 latches the position data output from the position counter 34 at the rising edge of the LD on timing, and synchronizes the position of the line light in the Y direction at that time with the falling timing of the LD on pulse from the MS 46. To the CPU 44. The line light moves while the LD is on, causing a deviation from the actual line light position. This is corrected in the CPU 44 by the line light moving speed, the LD on time, and the forward / reverse signal. I have.

On the other hand, the synchronization signal timing generator 39
C from the timing decoder 35 via the OR circuit 35 '
In response to the CD camera synchronization timing signal, it outputs a VD vertical synchronization signal synchronized with the HD horizontal synchronization signal. In connection with this VD vertical synchronizing signal, reading of light amount data of each pixel of the previous frame is started. At the same time, the accumulation of light quantity in each pixel starts, and the image by the line light 9 is CC
It is acquired on the CCD area image sensor 38 of the D camera 6.

An image on the CCD area image sensor 38 is read out as a light amount value (analog value) of each pixel via a driver 33 by a vertical register transfer clock, a horizontal register transfer clock, etc. from a synchronization signal timing generator 39. . This is, via the amplifier 47, the A / D
The data is input to the converter 48 and converted into digital data as VR data.
It is input to the AM image memory 40.

The horizontal address counter 42 is reset after a predetermined number of horizontal clocks from the fall of the horizontal synchronizing signal from the synchronizing signal timing generator 39, and then counts the horizontal clocks to thereby determine the horizontal position of the current pixel in the effective screen. Outputs the direction position (horizontal address). This horizontal address value is supplied to V-
It is input to the horizontal address of the RAM image memory 40.

On the other hand, the vertical address counter 43 is reset after a predetermined number of pulses of the horizontal synchronizing signal from the fall of the vertical synchronizing signal from the synchronizing signal timing generator 39, and thereafter is effective by counting the pulses of the horizontal synchronizing signal. The vertical position (vertical address) of the current pixel in the screen is output. This vertical address value is input to the vertical address of the V-RAM image memory 40 via the multiplexer 45.

The write timing generator 49 outputs a signal between the effective horizontal scanning section signal from the horizontal address counter 42 and the effective vertical scanning section signal from the vertical address counter 43.
A write signal is output to the V-RAM image memory 40 in synchronization with the horizontal clock. Thereby, the V-RAM image memory 40 stores each pixel data in the effective screen determined by the effective horizontal scanning section signal and the effective vertical scanning section signal.

The horizontal / vertical address generator 50 outputs the horizontal address signal to the multiplexer 41, the vertical address signal to the multiplexer 45, and the read signal to the V-RAM.
Output to the image memory 40. Multiplexers 41, 45
Is switched to the reading side in response to the switching signal from the CPU 44, and the image data of the V-RAM image memory 40 at the address determined by the horizontal address signal and the vertical address signal is sequentially read in synchronization with the reading signal. The reading of the image data is performed after the writing of the image data to the V-RAM image memory 40 is completed. This is because the multiplexer 4 receives a switching signal from the CPU 44.
1, 45 are guaranteed by switching from write to read mode.

[Circuit Configuration (Data Processing)] FIG.
3 illustrates a circuit configuration for processing image data stored in the RAM image memory 40. The circuit configuration centering on the V-RAM image memory 40 is the same as that illustrated in FIG. ing.

The multiplexers 41 and 45 are switched according to the switching signal.
Is switched to readout, the image data read out from the V-RAM image memory 40 in synchronization with the readout signal is input to the gradation data filter processing block 60 to remove noise. The gradation data filter processing block 60 is provided with two one-line buffers 61 and 62, whereby three lines of image data can be obtained simultaneously. These three lines of image data are input to the arithmetic circuit 63, where the flatness F of the image data is calculated, and is also input to the arithmetic circuit 64, where the maximum gradation value MAX and the minimum gradation value MIN are calculated. The difference ΔB is calculated. Further, the image data for three lines is also input to the band elimination filter 68 and is subjected to the band elimination filter. The output of the one-line buffer 61 is input to the delay circuit 69, and a delay corresponding to the operation processing time is applied. The arithmetic circuit 6
3, 64 and the processing of the band elimination filter 68 are 3
The processing is performed in units of × 3 pixel blocks.

The arithmetic circuit 65 calculates the ratio of the flatness F of the image data to the difference ΔB, and the comparator 66 compares the calculation result with a threshold value 66 ′. If it is less than the threshold value, the multiplexer 68 selects the image data subjected to the band elimination filter processing by the band elimination filter 68, and if it is more than the threshold value, the delay circuit 69 applies a delay corresponding to each operation time. The selected image data is output to the binarization processing block 70.

In the binarization processing block 70, the average value x (with a bar above) is calculated for each line by the average value calculation circuit 71 on the image data from the gradation data filter processing block 60. The deviation calculation circuit 72 calculates a standard deviation ρ for each line, and the threshold calculation circuit 74 calculates a threshold value (x + 1.5ρ). The comparator 75 is
This threshold value and 1 held in the one-line buffer 73
The image data for the lines is compared, and the image data is binarized.

The binarized image data from the binarization processing block 70 is converted to a binarized data filter processing block 80
Noise removal processing circuit 83 and two one-line buffers 8
1 and 82 are input. Noise removal filter processing circuit 8
3 receives three lines of image data simultaneously from the two one-line buffers 81 and 82 on the input side and the direct image data, and examines each 3 × 3 image block for small projections and isolated data; If so, a process for removing the data is performed. The output of the noise removal processing circuit 83 is
The data is input to the line buffer 85. The judgment circuit 87
It is determined whether all the lines are 0. If all the lines are 0, the output of the OR circuit 88 is selected by the multiplexer 89, and if not, the output of the 1-line buffer 85 is selected.
It is input to the one-line buffer 86. Since the image data of the one-line buffer 85 corresponds to the current image data, and the output of the noise removal processing circuit 83 and the image data of the one-line buffer 86 correspond to the image data before and after that,
If all the lines are 0, image data filled by OR processing of data at the same horizontal position of the previous and next lines is output.

The binarized image data from the binarized data filter processing block 80 is input to a center-of-gravity position calculation processing block 90, and the center-of-gravity position is calculated for each line. Rise detection circuit 9 of center-of-gravity position calculation processing block 90
1 detects that the binarized image data changes from “0” to “1”, and latches the horizontal address value of the horizontal address counter 93 at that time in the latch circuit 94. Also,
The falling detection circuit 92 detects that the binarized image data changes from “1” to “0”, and latches the horizontal address value of the horizontal address counter 93 at that time in the latch circuit 95. The center-of-gravity position calculating circuit 96 calculates the center-of-gravity position by averaging the horizontal address values at the time of the rise and the time of the fall.
The value is stored in the centroid position calculation result memory 100. The horizontal address counter 93 counts a horizontal clock for reading from the V-RAM image memory in order to obtain a horizontal address value. The horizontal address counter 93 is reset at the time of switching one line of image data.

[Measurement of Height Data] Next, in such a configuration, a process of obtaining height data of the wiring board or the cream solder by taking an example of the object to be measured as cream solder printed on the wiring board, FIG. This will be described with reference to the flow of FIG.

In general, when measuring the height of the cream solder, the brightness of the image of the resist surface between the cream solders is extremely lower than the brightness of the image of the cream solder portion, and the image of the line light on the resist surface There is a problem that it is not possible to determine the printing standard of cream solder because it is not possible to recognize the solder paste. If the light intensity is increased or the exposure time is increased, the image on the resist surface becomes recognizable, but this time, the image of the cream solder portion causes halation, and the center of gravity calculation cannot be processed accurately. Therefore, height measurement is performed using two reference lines as described below.

First, the CPU 44 generates a position command signal and a start signal in the linear motor drive command unit 31, and moves the linear motor 8 to a first reference position (register position of the wiring board) (step S11). When the CPU 44 reaches the first reference position, the CPU 44 sends a CCD camera synchronization timing pulse via the OR circuit 35 '(step S12), and generates an LD ON signal to generate the laser diode 1
Is turned on, for example, for 30 ms (step S13).

The laser light emitted from the laser diode 1 is condensed by a collimator lens 2 to form a parallel light beam 1a parallel to the optical center axis.
Is narrowed down to a spot light. This laser spot light is reflected by the light projecting mirror 4 in the direction of 45 degrees with respect to the incident angle, and
Incident on. With this lens 5, the laser spot light is
The light is expanded in one direction (X direction) by the prism effect, and becomes a line light 9 having a width of 14 μm and a length of 10 mm on the DUT 11. This line light has a field of view of 6.4 mm × 4.
The image is picked up by a non-interlaced CCD camera 6 of 8 mm.

After waiting for the time T1 in step S14,
In step S15, a CCD camera synchronization timing pulse is sent, and a synchronization signal timing generator 39 is driven to drive the CCD camera.
The image data of the image sensor 38 of the camera 6 is read into the V-RAM image memory 40 in synchronization with the output of the write timing generator 49 (step S16). The image data thus obtained is shown in FIG. 7 as the first reference line 110.

This image data undergoes each image processing in step S17. First, the multiplexers 41 and 45 are switched to the read mode by the switching signal of the CPU 44, and V is synchronized with the horizontal address and the vertical address according to the read signal from the horizontal / vertical address generator 50.
Image data is read from the RAM image memory 40;

The read image data is subjected to gradation data filtering in a gradation data filtering block 60. The arithmetic circuit 63 sets the pixel at the center of each 3 × 3 pixel block as the pixel of interest, and sets the flatness F
Is calculated. The flatness F is obtained as an average value of absolute values of differences between pixels around the target pixel, and the pixel columns are represented by A, B, and C.
.., The pixel rows are 1, 2, 3,...

[0041]

(Equation 1)

The flatness F is calculated by calculating The arithmetic circuit 64 calculates the difference ΔB between the maximum value of the pixels of each 3 × 3 pixel block and the minimum value of the gradation, and the arithmetic circuit 65 calculates F / ΔB. When F / ΔB is smaller than the threshold value 66 ′, the comparator 66 switches the multiplexer 67 because the image data is not flat. As a result, the band elimination filter circuit 68

[0043]

(Equation 2)

The data subjected to the band elimination filter processing is output. On the other hand, when ΔB = 0 or F / ΔB is larger than the threshold value, the data from the delay circuit 69 is selected and the band elimination filter processing is not performed. Data is output.

The image data that has been subjected to the gradation data filter processing is binarized by a binarization processing block 70. For this purpose, the arithmetic circuits 71 and 72 calculate the average value x and the standard deviation ρ of the gradation of each line. The comparator 75 calculates, for each pixel of the one-line buffer 73, the gradation data of the pixel as an average value x + ρ × 1.5 of the gradation of the line.
When the value is larger than the current pixel value, the current pixel value is set to 1;

Each of the binarized image data is sent to a binarized data filter processing block 80, and a noise removal processing circuit 83 removes small projection data and isolated data as noise for each 3 × 3 pixel block. I do. This noise removal corresponds to performing the filtering processes a to f as shown in FIG. When the pattern shown in FIG. 8 appears with the pixel at the center of 3 × 3 as the target pixel, the value of the target pixel is set to 0. The five types of filters other than f are rotated by 90 degrees and executed. The binarized image data thus subjected to the noise processing is sent to the one-line buffers 85 and 86. When all the pixels in one line are 0, the determination circuit 87 performs padding with reference to the preceding and following lines. For example, if all the pixels on the second line are 0, and if there is one pixel on the preceding and succeeding lines (first and third lines), the location of the one pixel is set to one.

The image data processed in this way is sent to the center-of-gravity position calculation processing block 90, where the arithmetic circuit 96 calculates the center-of-gravity position (average value). This position of the center of gravity is shown in FIG.
As shown in FIG. 1, 1 for pixel rows A, B, C.
This is performed by assigning serial numbers such as 2, 3,. In this example, regarding the first and second rows, the values of the pixels in the I and J columns are 1, and the number of the I column is 9 and the number of the J column is 10, so the centroid value of the first and second rows is 9. It becomes 5. Also 3,
For the fourth and fifth rows, the pixels in the I, H, and G columns are 1, and the barycentric value of each row is 9, which is the same as the number assigned to each column.
8 and 7. Hereinafter, the barycenter value of each row is obtained in the same manner.

FIG. 9A shows a graph in which the vertical axis represents the barycentric value and the horizontal axis represents the line number.
This result is stored in the memory 100 as height data of the first reference position (register position) in step S18.

Since the height data of the first reference position is obtained in this manner, next, line light is projected to the second reference position where cream solder is to be printed, and the height data of the surface is obtained. Is measured. Therefore, in step S21, the linear motor 8 operates at a constant speed of 4.8 mm according to the control signal.
/ Sec linearly moves to the second reference position in the Y direction (2.
The light projecting unit 7 coupled to the shaft of the linear motor 8 also moves the parallel light beam 1a in the Y direction accordingly.
Make a linear motion in parallel with. The light projecting unit 7 moves in the front-rear direction toward the parallel light beam, but since the focus lens 3 always receives the parallel light beam 1a, it does not affect the image forming operation of the focus lens 3.

The following steps S22 to S27 are the same as steps S12 to S17. The captured image data is indicated by 111 in FIG. 7, and the calculated height data is illustrated in FIG. 9B. ing. This result is obtained in step S2
At 8, the data is stored in the memory 100 as height data of the second reference position. Next, in step S29, a difference Δx between the average height data between the first reference line and the second reference line is calculated. In the example of FIG. 9, Δx = 171 μm−127 μm = 44 μm.

As described above, two lines of light are projected on the wiring board, and the parallelism of the measurement surface is measured. Next, cream solder is printed on the wiring board. Step S30 in FIG.
In step S31, it is confirmed that the cream solder is printed, the linear motor 8 is moved to the first reference position (the position 110 in FIG. 7), that is, the registration position. Steps S31 to S38 correspond to steps S11 to S11.
This is the same as S18. An image of the line light projected to the first reference position is shown as 112 in FIG.

Subsequently, at step S41, the linear motor 8
Is moved by 2.72 mm to the portion where the cream solder is printed (second reference position). Subsequent steps S42 to
Step S47 is the same as steps S32 to S37, except that the laser diode is turned on in step S43 with an exposure amount (exposure for 2 ms) suitable for cream solder. The image of this line light is indicated by 113a, 11 in FIG.
The image is as shown in FIG. In this case, the image of high brightness protruding to the right is the cream solder portion 113a, and the straight line portion of low brightness therebetween is the resist surface or pad surface 113b of the wiring board.

The position of the center of gravity calculated in step S47, that is, the height data of the cream solder is as shown in FIG. 11, and this height data is stored in the memory 1 in step S48.
00 is stored. This height data is processed assuming that the height of the first reference position is “0”. However, actually, the height of the resist surface set to “0” is not the resist surface on which the cream solder is printed. Therefore, the difference Δx (44 μm) between the height data between the first reference line and the second reference line obtained in step S29 corresponding to the difference between the heights of the two resist surfaces.
Then, the height of the cream solder portion is corrected according to the difference between the heights of the two resist surfaces (step S49). This is illustrated in FIG. 12, where the average height of the cream solder is 103 μm.

Since the average height of the cream solder previously measured by another measuring instrument was 102 μm, it was confirmed by the above method that the height of the cream solder portion was accurate. When acquiring the parallelism and the height of the cream solder part,
The interval between each line light was made to coincide with 2.72 mm, but this is for convenience of explanation. The parallelism is obtained by performing linear approximation, and if the position and interval of light projection are known, any position and interval can be used. And can be calculated.

As described above, in the above method, the height of the cream solder is measured with reference to the resist surface on which the cream solder is printed and another resist surface. Compensates for this and measures the height of the cream solder. In this case, the line light can be projected with an exposure amount suitable for the resist surface and the cream solder, respectively, and a clear photo-cut image of the resist surface and the cream solder can be obtained, so that the height of the cream solder can be accurately measured. Becomes possible.

In the above-described example, the resist surface and the cream solder portion were imaged with an exposure amount suitable for each of the lines by changing the light emission time of the line light. By changing the sensitivity, an image may be taken with an appropriate exposure amount.

[Measurement of Height Data Using Spreadsheet Software] In the above-described embodiment, the image data of the V-RAM image memory 40 was image-processed by the circuit configuration shown in FIG. The image data in the RAM image memory 40 can also be loaded into spreadsheet software for execution. V-RA
The image data of the M image memory 40 is 640 pixels in width × 4 pixels in height.
Since this is a bitmap image of 80 pixels, after converting each pixel into gradation data of 256 gradations, 640 columns × 4
Import into 80-cell spreadsheet software. Since the resolution between pixels is 10 μm, the pitch between cells is 10 μm when read into spreadsheet software because the pixels correspond to cells. However, since actual spreadsheet software has a functional limitation that the maximum number of columns is 256,
The processing is performed by taking in the gradation data of 0 columns × 480 rows.

First, the taken-in gradation data is taken out for every 3 × 3 cells, and the filter processing is performed by checking the flatness of the gradation. The cell at the center of the 3 × 3 cell is set as the cell of interest, and the flatness of the gradation around the cell is calculated. The average of the absolute values of the differences between the cells around the cell of interest is determined. Columns A, B, C
.., The rows are 1, 2, 3,..., For example, the cell of interest is B2, and the flatness F is calculated according to Equation 1 (corresponding to the calculation by the calculation circuit 63 in FIG. 4). Then 3 × 3
The ratio to the difference ΔB between the maximum value of the gray scale and the minimum value of the gray scale in the cell No. is obtained (corresponding to the arithmetic circuit 65). The cell is subjected to the band elimination filter of Equation 2 (corresponding to the filter circuit 68). If ΔB = 0 or if F / ΔB is greater than the threshold, do nothing. Next, the cell of interest is moved to B3, the above processing is executed, and the processing is performed as B4, B5,. Then, the processing shifts to the next line and the processing is sequentially performed as in C2, C3,.

When the gradation data filtering process is completed as described above, the process proceeds to the next binarization process. The average value and the standard deviation of the gradation of each row are calculated (corresponding to the arithmetic circuits 71 and 72).
Then, for each cell, when the gradation data of the cell is larger than the average of the gradation of the row + 1.5 × standard deviation (comparator 75
) Rewrites the current cell value to 1, and erases the current cell value in the following cases. Cells A1, B1, C1,...
For the cell A
For 2, 2, B2, C2,..., The average value and standard deviation in the second row are used. Each cell is either 1 or blank.

After the value of each cell is binarized in this way, the small projection data and the isolated data are considered to be noise. Therefore, erasure processing of these data is performed to remove noise. That is, the filter processing of a to f as shown in FIG. 8 is performed. Assuming that the cell at the center of 3 × 3 is the cell of interest, FIG.
, The value of the cell of interest is deleted.
The five types of filters other than f are rotated by 90 degrees and executed (corresponding to the noise removal processing circuit 83).

Next, each row is referred to, and if all are blank, padding is performed by referring to the array of cells of numerical value 1 in the upper and lower rows (corresponding to the determination circuit 87). Next, the center of gravity value is calculated for the cell of numerical value 1 in each row. This means that for columns A, B, C..., As shown in FIG.
The numerical value becomes the value of the center of gravity (corresponding to the center of gravity position calculation circuit 96). In this example, the values of the cells in columns I and J are 1 for the first and second rows, and the number of column I is 9,
Since the number in column J is 10, the centroid value of the first and second rows is 9.5.
Becomes For the third, fourth and fifth rows, I column, H column, G column
The cell in the column is 1, and the barycentric value of each row is 9, 8, 7 which is the same value as the number assigned to each column. Hereinafter, the barycenter value of each row is obtained in the same manner.

As described above, each processing block 60 in FIG.
70, 80, 90 can also be processed by software.

[0063]

As described above, according to the present invention, the first line light is projected on the flat portion near the protrusion to capture an image thereof, and the second line light is projected on the protrusion. The height of the protruding object obtained from the image of the second line light is obtained with reference to the height of the flat portion obtained from the image of the first line light. When it is not necessary to obtain the height data of the flat part before the object is formed, and when it is necessary to measure the height of the protrusion every time a protrusion is formed on the flat part, the tact time of the measurement is reduced. It can be significantly improved.

Further, the height of the flat portion at the position where the second line light is projected is obtained, and the height of the protruding object is calculated using the difference from the height of the flat portion obtained from the image of the first line light. Is corrected, it is possible to accurately measure the height of the protrusion even when the flat portions on which both lines are projected are not parallel.

Further, the flat portion and the protruding portion are imaged with exposure amounts suitable for the flat portion and the protruding portion, respectively, by changing the projection time of the line light, the intensity of the line light, or the imaging sensitivity. Clear imaging becomes possible, and the quality of height data can be improved.

In the height data processing according to the present invention, the gradation data of the imaged pixel is binarized after being subjected to the flattening processing, so that stable height data can be obtained. In addition, when a blank line is generated as a result of performing a filtering process on the binarized data, the data is embedded in the blank line according to the array of the binarized data in the preceding and succeeding lines. Height data is required.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a height measuring device used in the present invention.

FIG. 2 is a side view of the height measuring device of FIG.

FIG. 3 is a circuit diagram showing a circuit configuration for acquiring image data from an image obtained by projecting line light.

FIG. 4 is a circuit diagram showing a circuit configuration for processing acquired image data.

FIG. 5 is a flowchart showing a flow of processing of an image obtained when two line lights are emitted before printing the cream solder.

FIG. 6 is a flowchart illustrating a flow of processing of an image obtained when two line lights are emitted after printing the cream solder.

FIG. 7 is an explanatory diagram showing an image obtained when two line lights are emitted before printing cream solder.

FIG. 8 is an explanatory diagram showing filter data used for a filtering process on image data.

FIG. 9 is a diagram showing the height of a flat portion obtained from image data obtained when two line lights are projected before printing cream solder.

FIG. 10 is an explanatory diagram showing an image obtained when two line lights are projected after printing the cream solder.

FIG. 11 is a diagram showing the height of the cream solder obtained from the image data of the cream solder part.

FIG. 12 is a diagram showing corrected height data of cream solder.

FIG. 13 is an explanatory diagram showing an example for obtaining a barycentric value from pixel or cell information.

FIG. 14 is a perspective view showing a configuration of a conventional three-dimensional measuring device.

[Explanation of symbols]

 1 laser light source 5 line generator 6 CCD camera 9 line light

Claims (9)

[Claims] A line light is projected onto an object to be measured having a protrusion projecting from the flat portion, and the flat portion and the protrusion which are cut by the line light are imaged, and the protrusion from the flat portion is detected by a light cutting method. In a height measuring method for measuring the height of a projection, a first line light is projected on a flat portion in the vicinity of the projection to capture an image of the projection, and a second line light is projected on the projection to capture the image. And the height of the protrusion obtained from the image of the second line light is set to the first height.
A height measurement method, wherein the height is calculated based on the height of the flat portion obtained from the image of the line light. 2. A height of a flat portion at a position where the second line light is projected, and a height of the protrusion is determined by using a difference from a height of the flat portion obtained from an image of the first line light. The height measuring method according to claim 1, wherein the height is corrected. 3. The flat portion and the protruding portion are imaged with an exposure amount suitable for the flat portion and the protruding portion by changing the projection time of the line light, the intensity of the line light, or the imaging sensitivity. The height measuring method according to claim 1 or 2, wherein: 4. A height data processing method for imaging a projecting object cut by line light and processing height data of the projecting object obtained by a light cutting method. And, for each pixel, check the flatness of the gradation of the surrounding pixels. If not flat, perform gradation processing such as performing filter processing on the target pixel. A height data processing method, comprising performing binarization on data and converting an image of a protrusion into binary data. 5. An average value and a standard deviation of the gradation data subjected to the filtering process for each row, a threshold value determined from the average value and the standard deviation for each row, and a gradation of each pixel in the row. 5. The height data processing method according to claim 4, wherein each pixel is binarized by comparing data. 6. A height data processing method for imaging a protrusion cut by line light and processing height data of the protrusion obtained by a light cutting method, wherein the images of the protrusions are arranged in rows and columns. The pixel data is extracted as binarized data, and the binarized data is filtered. If a blank line is obtained as a result of the filter processing, a blank line is set according to the binarized data array in the preceding and following rows. A height data processing method, wherein data is embedded in a height. 7. A projecting object having a projection projecting from a flat portion is irradiated with line light, the flat portion and the projecting object cut by the line light are imaged, and the projecting object from the flat portion is projected by a light cutting method. A height measuring device for measuring the height of the object, wherein a first portion and a second
A light projecting device for projecting the first and second line lights, a flat portion near the projecting object on which the first and second line lights are projected, and a unit for imaging an image of the projecting object; Means for processing the image of the flat portion and the protrusion near the protrusion by the line light to calculate the height of the flat portion and the protrusion, and calculating the height of the protrusion by changing the height of the flat portion near the protrusion. A height measuring device, comprising: means for calculating based on a reference. 8. A height of the flat portion at a position where the second line light is projected, and a height of the protruding object is calculated using a difference from a height of the flat portion obtained from an image of the first line light. The height measuring device according to claim 7, wherein the height is corrected. 9. The flat portion and the projecting portion are imaged with an exposure amount suitable for each of the flat portion and the projecting portion by changing the light projection time of the line light, the intensity of the line light, or the imaging sensitivity. The height measuring device according to claim 7 or 8, wherein: