TW201713919A - Three-dimensional measurement device - Google Patents

Abstract

Provided is a three-dimensional measurement device capable of maintaining necessary measurement accuracy while enhancing measurement speed when carrying out three-dimensional measurement using a phase shift method. A substrate inspection device 1 is provided with an illumination device 4 for irradiating a prescribed light pattern from diagonally above onto the surface of a printed circuit board 2, a camera 5 for imaging the part of the printed circuit board 2 onto which the light pattern is irradiated, and a control device 6 for carrying out various control, image processing, and calculation in the substrate inspection device 1. The control device 6 carries out highly accurate three-dimensional measurement by using a four-image method to acquire image data for an inspection area that includes cream solder and satisfies a prescribed determination condition while carrying out three-dimensional measurement in a short period of time by using a two-image method to acquire image data for other inspection areas.

Description

Three-dimensional measuring device

The present invention relates to a three-dimensional measuring apparatus for performing three-dimensional measurement using a phase shifting method.

Generally, in the case where an electronic component is mounted on a printed substrate, solder paste is first printed on a predetermined electrode pattern disposed on the printed substrate. Then, the electronic component is temporarily fixed on the printed substrate by the adhesiveness of the solder paste. Thereafter, the printed substrate is guided to a reflow oven and subjected to a predetermined reflow process for soldering. Recently, it is necessary to check the printing state of the solder paste before being guided to the reflow furnace, and a three-dimensional measuring device is sometimes used for such inspection.

In recent years, there has been proposed a so-called non-contact three-dimensional measuring device using light, and for example, a technique relating to a three-dimensional measuring device using a phase shifting method has been proposed.

In a three-dimensional measuring apparatus using the phase shifting method, a combination of a light source that emits a predetermined light source and a light pattern that converts light from the light source into a light intensity distribution having a sinusoidal shape (striped shape) is used. The irradiation means is configured to irradiate the light pattern on the printed substrate (measured object). Next, the dots on the substrate are observed using a photographing means disposed on the front side. In terms of shooting means, the lens and the imaging element are used. CCD camera, etc.

In the above configuration, the light intensity (luminance) I of each pixel on the image data captured by the photographing means is obtained by the following formula (U1).

Where f: gain, e: offset (offset), : The phase of the light pattern.

Here, by controlling the above-described grid by transfer or switching, the phase of the light pattern is, for example, four stages ( +0, +90°, +180°, +270°), the image data having the intensity distributions I ₀ , I ₁ , I ₂ , and I ₃ corresponding thereto are taken, and f (gain) and e (offset) are deleted according to the following formula (U2) ), find the phase .

Then use this phase The height (Z) of each coordinate (x, y) on the printed circuit board is obtained based on the triangulation principle (for example, refer to Patent Document 1).

In recent years, in recent years, it has been proposed to replace the above-mentioned four-time shooting mode, and to change the phase of the light pattern in three stages, and to obtain the phase from the three types of image data. The third shooting method (for example, refer to Patent Document 2).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 5-280945

[Patent Document 2] JP-A-2002-81924

However, since the 4 shots are measured based on more image data, high-precision measurement can be performed, but in measurement (especially It takes time to obtain image data. Conversely, the measurement method has a shorter measurement time for the three shots, and the measurement accuracy for the smaller size solder paste (measurement object) is also insufficient.

Therefore, in the inspection of a printed circuit board containing a solder paste of a small size which requires high-precision measurement, it takes more time to measure.

For example, it is assumed that for a predetermined measurement area (photographing area), the time taken for one shot is [10 msec], and the time for switching the grid for one time is [20 msec], respectively. The time required for the completion of the imaging processing (the last imaging processing) of all the measurement areas is as follows: as shown in Fig. 8 (a), the time required for the imaging processing [10 ms] ×4 times] + [Time required for switching of the grid [20 ms] × 3 times] = total [100 msec]. On the other hand, in the case of the three-shot mode, as shown in FIG. 8(b), it becomes [time required for imaging processing [10 ms] × 3 times] + [time required for switching of the grid [20 ms] ×2 times] = total [70 msec].

Of course, when a plurality of measurement areas are set on one printed circuit board, the time required for measurement of the one printed circuit board is several times.

Further, the above-described problems are not necessarily limited to the height measurement of the solder paste or the like printed on the printed circuit board, and include the field of other three-dimensional measuring devices.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a three-dimensional measuring apparatus capable of maintaining a required measurement accuracy and improving a measurement speed when three-dimensional measurement is performed by a phase shift method.

Hereinafter, each means suitable for solving the above problems will be described in detail. In addition, due to the need to attach a special effect on the corresponding means.

Means 1. A three-dimensional measuring apparatus comprising: an irradiation means for irradiating a light object having a stripe-shaped light intensity distribution on a workpiece (for example, a printed board); and an image capturing means capable of photographing and irradiating the light pattern a predetermined measurement area (measurement area) on the object to be measured; and an image acquisition means configured to control the irradiation means and the imaging means to change a phase of the light pattern in plural, and obtain the light pattern in the light pattern The plurality of images (image data) of the aforementioned measurement area are respectively photographed, and the number of images to be acquired (photographed) for the measurement area may be changed according to the measurement area; and the image processing means may be based on the foregoing The image obtained by the image acquisition means performs three-dimensional measurement on the measurement target (for example, solder paste or the like) in the measurement area by the phase shift method, and the image acquisition means includes the measurement that satisfies the predetermined determination condition in the measurement area. In the case of the object, the first predetermined number (for example, four types) of phase irradiation and the photographing of the light pattern are obtained. In the case where the measurement target region that does not satisfy the above-described determination condition is not included in the measurement area, the second predetermined number (for example, three types) of the first predetermined number (for example, three types) are acquired and photographed. The second predetermined number of images obtained by the light pattern.

Generally, printing is performed by a three-dimensional measuring device Various types of solder pastes having different sizes are printed on the substrate, and the types and arrangements thereof vary depending on the measurement areas. That is, even in the case of a printed substrate containing a solder paste of a small size requiring high-precision measurement, there is a case where a measurement area which does not require high-precision measurement exists.

However, the conventional technique utilizes the same measurement method set in advance on all the measurement areas set on the printed substrate (for example, in the case of performing high-precision measurement, the phase shifting method is used four times, and the measurement accuracy is not required to the extent When the measurement is performed in a shorter time, the measurement is performed uniformly using the three-phase phase shift method.

On the other hand, according to the above-described means 1, the measurement area including the measurement target that satisfies the predetermined determination condition (for example, the size is smaller than the predetermined value) performs the three-dimensional measurement with higher precision according to the first predetermined number (for example, four types) of the image. On the other hand, for the measurement area other than the measurement area, the three-dimensional measurement can be performed in a shorter time based on the second predetermined number (for example, three types) of images smaller than the first predetermined number.

As a result, when the three-dimensional measurement is performed by the phase shift method, it is possible to maintain the measurement accuracy necessary for the measurement target (measurement object to be measured with high accuracy) that satisfies the predetermined determination condition and to increase the measurement speed.

Further, the above-mentioned "established determination condition" includes that the size of the measurement target is smaller than a predetermined value (for example, "area", "volume", "peripheral length" or "short side length" is less than a predetermined value) or the measurement object belongs to the predetermined value. The attribute attribute (for example, the type of the part to be solder paste to be measured is a predetermined type). In addition, whether or not the measurement area contains a measurement target that satisfies a predetermined determination condition, and the design information of the object to be measured that is previously memorized according to a predetermined memory means [cover] Information, etc.] to proceed.

The apparatus according to the first aspect of the invention, wherein the image acquisition means acquires the first predetermined number (for example, four types) of images, wherein the image processing means satisfies the determination in the measurement area The measurement target of the condition is three-dimensionally measured by the phase shift method based on the first predetermined number of images, and the measurement target that does not satisfy the determination condition in the measurement region is based on the second predetermined number (for example, three types). The image is measured by phase shifting in three dimensions.

According to the above-described means 2, for a measurement object that does not satisfy the predetermined determination condition (the measurement accuracy does not require such a measurement object), the three-dimensional measurement can be performed in a short time based on fewer images. As a result, it is possible to further increase the measurement speed.

In addition, in the case of acquiring the image of the first predetermined number (for example, four types), the measurement accuracy of the "measurement target that does not satisfy the predetermined determination condition" and the second predetermined number (for example, 3) may be used. The measurement accuracy of the "measurement target that does not satisfy the predetermined determination condition" is equal in the case where the second predetermined number of images obtained by the phase illumination and the photographing of the light pattern are three-dimensionally measured.

The three-dimensional measuring apparatus according to the means 1 or 2, wherein the condition setting means capable of setting the determination condition in accordance with an external operation is provided.

According to the above means 3, the predetermined decision bar can be arbitrarily set It can be used to improve convenience and versatility.

The three-dimensional measuring apparatus according to the third aspect, comprising a predetermined time display means for displaying a predetermined time spent on the measurement of the object to be measured under the determination condition set by the condition setting means.

According to the above-described means 4, it is not necessary to actually operate the three-dimensional measuring device a plurality of times in advance in order to find an optimum determination condition that satisfies the measurement time and measurement accuracy required by the operator. As a result, convenience can be improved.

The three-dimensional measuring apparatus according to any one of the above-mentioned means, wherein the image capturing means includes the first predetermined number in the measurement region including the measurement target that satisfies the determination condition. Four or three types of images obtained by phase irradiation and photographing of a light pattern, and the measurement target that satisfies the above-described determination condition is not included in the measurement region, and the second predetermined number is obtained. There are two types of images obtained by phase irradiation and photographing of light patterns.

According to the above-described means 5, for a measurement object that does not satisfy the predetermined determination condition (the measurement accuracy does not require such a measurement object), the three-dimensional measurement can be performed in a short time based on fewer images. As a result, it is possible to further increase the measurement speed.

The three-dimensional measuring device according to any one of the above-mentioned means, wherein the image capturing means includes the measurement target that satisfies a specific condition among the determination conditions in the measurement region, and obtains the Four kinds of images of the first four types of phase irradiation and four types of images obtained by photographing light patterns, When the measurement target that satisfies the above-described determination condition is included in the measurement region, but the measurement target that satisfies the specific condition is not included, three types of phase illumination and photographing light patterns are obtained as the first predetermined number. In the case where the measurement target that satisfies the above-described determination condition is not included in the measurement region, two kinds of images obtained by the phase illumination and the photographing light pattern of the second predetermined number are obtained.

According to the above-described means 6, in addition to the effects of the above-described means 5, the difference in the measurement object can be more finely matched, and the measurement speed can be further improved.

Further, in the means 6 of the above-described means 2, in the case where the image acquisition means acquires four kinds of images, the image processing means is configured to satisfy the specific condition in the measurement region. The measurement object is subjected to three-dimensional measurement by the phase shift method according to the four types of images, and the three-dimensional measurement is performed by the phase shift method based on the three kinds of images for the measurement object that does not satisfy the specific condition and satisfies the above-described determination condition in the measurement region. For the measurement target that does not satisfy the above-described determination condition in the measurement area, the three-dimensional measurement is performed by the phase shift method based on the two types of images, and in the case where the image acquisition means acquires three types of images, the image processing means is The measurement object that satisfies the above-described determination condition in the measurement region is subjected to three-dimensional measurement by a phase shift method according to three kinds of images. In the case where the measurement target that does not satisfy the above-described determination condition in the measurement region is subjected to three-dimensional measurement by the phase shift method based on the two kinds of images, the measurement accuracy can be further improved.

The method of claim 3, wherein the image processing means uses a relationship between a gain and an offset determined by a predetermined imaging condition and a pixel on the image. The value of the gain or offset of the pixel determined by the luminance value can be three-dimensionally measured by the phase shift method according to the two types of images.

According to the above means 7, by using the relationship between the gain A and the offset B determined by the predetermined shooting conditions (for example, A = K (proportional constant) × B), and each pixel on the image (x, y) The value of the gain A(x, y) or the offset B(x, y) of the pixel (x, y) determined by the luminance value V(x, y) can be shifted according to the two types of images. The phase method performs three-dimensional measurement.

Therefore, compared with the conventional technique that requires four or three types of images, the measurement time can be dramatically shortened.

In general, the "illumination means" has a light source that emits a predetermined light source and a light pattern that converts light from the light source into a light intensity distribution having a stripe shape, and is configured to illuminate the object to be measured. pattern.

Further, the light system irradiated from the light source is first attenuated while passing through the grid, and then attenuated while being reflected by the object to be measured (measured object), and finally A/D conversion (analog-digital conversion) is performed by the photographing means. After being attenuated, the luminance value of each pixel as the image is obtained.

Therefore, the luminance value of each pixel of the image captured by the photographing means can be illuminated from the light source by the brightness (luminance) of the light source. The attenuation rate of the light passing through the grille, the reflectance of the light when the object is reflected, and the conversion efficiency when the imaging means performs A/D conversion (analog-digital conversion) are expressed.

For example, the brightness of the light source (uniform light): L

Transmittance of the grid: G = αsin θ + β α, β is an arbitrary constant.

Set to: reflectance of the coordinates (x, y) on the object to be measured: R(x, y)

Conversion efficiency of each pixel of the shooting means (photographing element): E

The luminance value of the pixel on the image corresponding to the coordinate (x, y) on the object to be measured: V(x, y)

Gain of the light pattern of the coordinates (x, y) on the object to be measured: A(x, y)

Offset of the light pattern of the coordinates (x, y) on the object to be measured: B(x, y)

In the case, it can be expressed by the following formula (F1).

V(x,y)=L×G×R(x,y)×E=A(x,y)sin θ +B(x,y)‧‧‧(F1)

Here, the gain A(x, y) is the difference between the luminance value V(x, y) _MAX of the light of "sin θ = 1" and the luminance value V (x, y) _MIN of the light of "sin θ = -1". Representation, therefore, for example, is set to: transmittance of the grid at θ = 0 (= average transmittance): Gθ ₌₀

Transmittance of the grid at θ=π/2 (=maximum transmittance): Gθ ₌ π _/2

Transmittance of the grid at θ=-π/2 (=minimum transmittance): Gθ _=- π _/2

In the case, it can be expressed by the following formula (F2).

A(x,y)={(L×G _{θ =π/2} ×R(x,y)×E)-(L×G _{θ =−π/2} ×R(x,y)×E)}/ 2={(L×R(x,y)×E)×(G _{θ =π/2} -G _{θ =-π/2} )}/2‧‧‧(F2)

Further, the offset amount B(x, y) is the luminance value V(x, y) of the light at "sin θ = 0", and is based on the luminance value V (x, y) of the light at "sin θ = 1". Since _MAX is based on the average value of the luminance value V(x, y) _MIN of the light of "sin θ = -1", it can be expressed by the following formula (F3).

B(x,y)=L×G _{θ =0} ×R(x,y)×E={(L×G _{θ =π/2} ×R(x,y)×E)+(L×G _{θ = -π/2} × R(x, y) × E)}/2 = {(L × R(x, y) × E) × (G _{θ = π/2} + G _{θ = -π/2} )} / 2‧‧‧(F3)

That is, the maximum value of the luminance value V(x, y) _MAX , the minimum value V (x, y) _MIN , and the average value V (x, y) _AV can be expressed by the following equations (F4), (F5), ( F6) indicates that the relationship shown in the graph of Fig. 3 is obtained.

V(x,y) _MAX =(L×G _{θ =π/2} ×R(x,y)×E)=B(x,y)+A(x,y)‧‧‧(F4)

V(x,y) _MIN =(L×G _{θ =−π/2} ×R(x,y)×E)=B(x,y)-A(x,y)‧‧‧(F5)

V(x,y) _AV =(L×R(x,y)×E)×(G _{θ =π/2} +G _{θ =-π/2} )/2=B(x,y)‧‧‧( F6)

It can be seen from Fig. 3 that the maximum value of the luminance value V(x, y) _MAX in the predetermined coordinate (x, y) and the minimum value of the luminance value V(x, y) _MIN mean V (x, y) _AV becomes the offset B(x, y), the difference between the offset B(x, y) and the maximum value V(x, y) _MAX and the offset B(x, y) and the minimum value The difference between V(x, y) _MIN becomes the gain A(x, y), respectively.

Further, since the luminance value V(x, y) changes in proportion to the luminance L of the light source or the reflectance R(x, y), for example, the value of the gain A and the offset B at the coordinate position at which the reflectance R becomes half. It has also become half.

Then, the above formulae (F2) and (F3) are represented by the following formulas (F2 ' ) and (F3 ' ), and after the two are added together, the following formula (F7) can be derived.

2A(x,y)/(G _{θ =π/2} -G _{θ =-π/2} )=(L×R(x,y)×E)‧‧‧(F2′)

2B(x,y)/(G _{θ =π/2} +G _{θ =-π/2} )=(L×R(x,y)×E)‧‧‧(F3′)

2A(x,y)/(G _{θ =π/2} -G _{θ =-π/2} )=2B(x,y)/(G _{θ =π/2} +G _{θ =-π/2} )‧‧‧ (F7)

Then, when the above formula (F7) is solved for A(x, y), the following formula (F8) is obtained, and the graph shown in Fig. 4 can be displayed.

A(x,y)=B(x,y)×(G _{θ =π/2} -G _{θ =−π/2} )/(G _{θ =π/2} +G _{θ =-π/2} )=K× B(x,y)‧‧‧(F8) where the proportional constant K=(G _{θ =π/2} -G _{θ =-π/2} )/(G _{θ =π/2} +G _{θ =-π/2} )

That is, in the case where one of the luminance L or the reflectance R(x, y) of the light source is fixed and the other is changed, the offset B(x, y) is increased or decreased, and the gain A(x, y) also increases or decreases in proportion to the offset B(x, y). According to the equation (F8), if one of the gain A or the offset B is known, the other one can be found. Here, the proportionality constant K is determined by the transmittance G of the grid regardless of the luminance L and the reflectance R of the light source. That is, in other words, means 2, 3 as described below.

The three-dimensional measuring apparatus according to the seventh aspect, wherein the relationship between the gain and the offset amount is such that the gain and the offset amount are mutually uniquely determined.

If the gain A and the offset B are mutually uniquely determined, the offset B or the offset can be obtained from the gain A by, for example, creating a mathematical table or table data indicating the relationship between the gain A and the offset B. The offset B is used to find the gain A.

The three-dimensional measuring apparatus according to the seventh aspect, wherein the relationship between the gain and the offset is such that the gain and the offset amount are proportional.

If the gain and the offset are in a proportional relationship, for example, it can be expressed by a relational expression such as A=K×B+C (where C: dark current (offset) of the camera), and the gain A can be obtained. The amount B is shifted, or the gain A is obtained from the offset B. Further, a configuration such as the following means 10 can be employed.

The three-dimensional measuring apparatus according to any one of the above-mentioned means, wherein each of the two types of images is obtained when the relative phase relationship of the light patterns of the two types of images is set to 0 or γ, respectively. In the case where the luminance values of the pixels are V ₀ and V ₁ respectively, the image processing means obtains the phase θ satisfying the relationship of the following equations (1), (2), and (3), and performs three-dimensional measurement based on the phase θ.

V ₀ =Asinθ+B...(1)

V ₁ =Asin(θ+γ)+B...(2)

A = KB (3) where γ ≠ 0, A: gain, B: offset, K: proportional constant.

According to the above means 10, by substituting the above formula (3) into the above formula (1), the following formula (4) can be derived.

V ₀ = KBsin θ + B (4) When this is solved for the offset B, the following formula (5) can be derived.

B = V _{0 / (} Ksin θ + 1) (5) Further, by substituting the above formula (2) into the above formula (2), the following formula (6) can be derived.

V ₁ =KBsin(θ+γ)+B (6) When the above formula (6) is substituted into the above formula (5) and is sorted as shown in the following [number 7], the following formula (7) can be derived. ).

V ₁ =K ×{V ₀ /(Ksin θ +1)}sin( θ + γ )+{V ₀ /(Ksin θ +1)} V ₁ ×(Ksin θ +1)=KV ₀ sin( θ + γ )+V ₀ =KV ₀ {sin θ cos γ +sin γ cos θ }+V ₀ -V ₁ Ksin θ +KV ₀ cos γ sin θ +KV ₀ sin γ cos θ +V ₀ -V ₁ =0 K (V ₀ cos γ -V ₁ )sin θ +KV ₀ sin γ cos θ +(V ₀ -V ₁ )=0 (V ₀ cos γ -V ₁ )sin θ +V ₀ sin γ cos θ +(V ₀ -V ₁ )/K=0‧‧‧(7)

Here, when "V ₀ cos γ - V ₁ = a", "V ₀ sin γ = b", and "(V ₀ - V ₁ ) / K = c" are set, the above formula (7) can be expressed as follows (8).

Asin θ + bcos θ + c = 0 (8) Here, as shown in the following [Equation 8], when the above equation (8) is solved for the phase θ, the following [9] can be derived. Said (9).

b ² - b ² sin ² θ = c ² +2 ac sin θ + a ² sin ² θ

( a ² + b ² )sin ² θ +2 ac sin θ + c ² =0

Where a=V ₀ cos γ -V ₁

b=V ₀ sin γ

c=(V ₀ -V ₁ )/K

Therefore, in the above-described means 10, it is described that "the phase θ of the relationship of the following formulas (1), (2), and (3) is obtained, and the three-dimensional measurement is performed based on the phase θ", in other words, "based on the following formula (9) The phase θ is obtained, and the three-dimensional measurement is performed based on the phase θ. Of course, the algorithm for obtaining the phase θ is not limited to the above formula (9), and other configurations may be employed if the relationship of the above formulas (1), (2), and (3) is satisfied.

Further, considering the dark current C or the like of the above-described camera, it is possible to further improve the measurement accuracy.

Means 11. The three-dimensional measuring apparatus according to the means 10, wherein γ = 180° is set.

According to the above-described means 11, three-dimensional measurement is performed based on two kinds of images respectively captured under two kinds of light patterns having a phase difference of 180 degrees.

The following formula (10) is derived by setting γ = 180° in the above formula (2).

V ₁ =Asin(θ+180°)+B=-Asinθ+B (10) Next, the following formula (11) can be derived from the above formulas (1) and (10), when this is When the quantity B is solved, the following formula (12) can be derived.

V ₀ +V ₁ =2B...(11)

B = (V ₀ + V ₁ ) / 2 (12) Then, by substituting the above formula (12) into the above formula (3), the following formula (13) can be derived.

A = KB = K (V ₀ + V ₁ ) / 2 (13) Further, when the above formula (1) is arranged for "sin θ", it is as shown in the following formula (1 ' ).

Sin θ = (V ₀ - B) / A (1 ' ) Next, by substituting the above formulas (12) and (13) into the above formula (1 ' ), the following formula (14) can be derived.

Sin θ={V ₀ -(V ₀ +V ₁ )/2}/{K(V ₀ +V ₁ )/2}=(V ₀ -V ₁ )/K(V ₀ +V ₁ )...( 14) Here, when the above formula (14) is solved for the phase θ, the following formula (15) can be derived.

θ=sin ^-1 [(V ₀ -V ₁ )/K(V ₀ +V ₁ )] (15) That is, the phase θ can be obtained by the known luminance values V ₀ , V ₁ and constants K is specific.

As described above, according to the above-described means 11, the phase θ can be obtained based on a simpler calculation formula, and the processing can be speeded up when the three-dimensional measurement of the measurement target is performed.

The method of claim 3, wherein the three-dimensional measuring device according to the means 10 is set to γ=90°.

According to the above-described means 12, three-dimensional measurement is performed based on two kinds of images respectively captured under two kinds of light patterns having a phase difference of 90°.

The following formula (16) is derived by setting γ = 90° in the above formula (2).

V ₁ = Asin (θ + 90°) + B = Acos θ + B (16) When the above formula (16) is arranged for "cos θ", it is as shown in the following formula (17).

Cos θ = (V ₁ - B) / A (17) Further, when the above formula (1) is arranged for "sin θ", the above formula (1 ' ) is obtained as described above.

Sin θ = (V ₀ - B) / A (1 ' ) Next, when the above formulas (1 ' ) and (17) are substituted into the following formula (18), the following formula (19) is obtained, and then The following formula (20) is derived.

Sin ² θ+cos ² θ=1...(18)

{(V ₀ -B)/A} ² +{(V ₁ -B)/A} ² =1...(19)

(V ₀ - B) ² + (V ₁ - B) ² = A ² (20) Next, when the above formula (3) is substituted into the above formula (20), it becomes the following formula (21), and then After finishing this, the following formula (22) is derived.

(V ₀ -B) ² +(V ₁ -B) ² =K ² B ² (21)

(2-K ² )B ² -2(V ₀ +V ₁ )B+V ₀ ² V ₁ ² =0 (22) Here, when the above formula (22) is solved for the offset amount B , the following formula (23) can be derived.

Where B>0

That is, the offset B can be specified by the known luminance values V ₀ , V ₁ and the constant K.

In addition, when the above formulae (1 ' ) and (17) are substituted into the following formula (24), the following formula (25) is obtained, and after finishing, the following formula (26) is derived.

Tanθ=sinθ/cosθ...(24)

={(V ₀ -B)/A}/{(V ₁ -B)/A}...(25)

=(V ₀ -B)/(V ₁ -B)...(26)

Next, when the above formula (26) is solved for the phase θ, the following formula (27) can be derived.

θ=tan ^-1 {(V ₀ -B)/(V ₁ -B)}..(27)

That is, the phase θ can be specified by the known luminance values V ₀ , V ₁ and the constant K by using the above formula (23).

As described above, according to the above-described means 2, since the phase θ can be obtained based on the calculation formula using "tan ^-1 ", the three-dimensional measurement can be performed in the 360° range of -180° to 180°, and the measurement range can be further increased.

The three-dimensional measuring apparatus according to any one of the means 7 to 12, further comprising: a relationship grasping means for grasping the relationship between the gain and the offset amount in advance.

For the relationship grasping means, for example, a configuration in which the relationship between the gain and the offset amount is corrected in advance is exemplified. For example, the reference plate is irradiated with three or four kinds of phase-changing light patterns, and the gain A and the offset B in each pixel are specified by the three or four kinds of images respectively taken under the above-mentioned The constant (K) is determined in advance by the formula (3). According to this configuration, it is possible to perform measurement with higher accuracy in each pixel.

Further, the relationship grasping means may be, for example, a configuration in which the relationship between the image grasping gain and the shift amount captured when the measurement is performed (in actual measurement). According to this configuration, the correction work can be omitted, and the measurement time can be further shortened.

Here, the above-mentioned "images taken when measuring separately" are, of course, included in two kinds of phase changes, in addition to four or three kinds of images respectively taken under four or three kinds of phase-changing light patterns. Two types of images taken separately under the light pattern.

Further, in the case of grasping the relationship between the gain and the offset amount in two types of images respectively captured under the light patterns of the two kinds of phase changes, for example, the full-pixel of the image is obtained using the above formula (12). The shift amount B, in which the value of the extracted offset B is a uniform luminance value V of the pixel, is formed as a histogram. Next, the maximum value V _{MAX of the} luminance value and the minimum value V _{MIN are} determined from the histogram.

As described above, the average value of the maximum value V _MAX and the minimum value V _MIN of the luminance value becomes the offset amount B, and half of the difference between the maximum value V _MAX and the minimum value V _MIN becomes the gain A. According to this, the constant K can be determined from the above formula (3).

The three-dimensional measuring device according to any one of the above-mentioned means, wherein the measuring object is a solder paste printed on a printed substrate as the object to be measured or a wafer formed as the object to be measured Solder bumps on the substrate.

According to the above means 14, the solder paste printed on the printed substrate or the height of the solder bump formed on the wafer substrate can be measured. Moreover, in the inspection of the solder paste or the solder bump, the quality of the solder paste or the solder bump can be determined based on the measured value. Therefore, in this inspection, the effects of the above-described respective means are achieved, and the quality determination can be performed with high precision. As a result, it is possible to improve the inspection accuracy in the solder print inspection device or the solder bump inspection device.

1‧‧‧Substrate inspection device

2‧‧‧Printing substrate

4‧‧‧Lighting device

4a‧‧‧Light source

4b‧‧‧LCD grille

5‧‧‧ camera

6‧‧‧Control device

23‧‧‧Display device

24‧‧‧Image data memory means

25‧‧‧ calculus result memory device

26‧‧‧Set data memory device

230‧‧‧ Condition setting screen

A‧‧‧ Gain

B‧‧‧Offset

K‧‧‧proportional constant

Js, Jb‧‧‧ solder paste

W1~W4‧‧‧ inspection area

Fig. 1 is a schematic perspective view showing a substrate inspecting apparatus.

Fig. 2 is a block diagram showing the electrical configuration of the substrate inspecting device.

Figure 3 is a graph showing the relationship between the brightness or reflectance of a light source and the luminance value.

Figure 4 is a graph showing the relationship between gain and offset.

Fig. 5 is a view showing a condition setting screen.

Figure 6 is a flow chart showing the inspection procedure.

Fig. 7 is a schematic view showing an example of a printed substrate for explaining the arrangement relationship of solder paste or inspection regions and the like.

8(a) to (c) are timing charts for explaining processing operations of the camera and the illumination device.

Fig. 9 is a table showing the distribution of the distribution of the number of luminance values included in each data section.

Fig. 10 is a histogram showing the distribution of the number of luminance values included in each data section.

Fig. 11 is a view showing a condition setting screen in another embodiment.

Fig. 12 is a view showing a condition setting screen in another embodiment.

[First Embodiment]

Hereinafter, an embodiment will be described with reference to the drawings. Fig. 1 is a schematic block diagram showing a substrate inspecting apparatus 1 including a three-dimensional measuring apparatus according to the present embodiment. As shown in the figure, the substrate inspection apparatus 1 includes a mounting table 3 on which a solder substrate to be printed with a solder paste to be printed is mounted, and a printing substrate 2 as an object to be measured. 4. The surface of the printed circuit board 2 is irradiated with a predetermined light pattern from obliquely upward; the camera 5 as a photographing means is used to photograph the portion of the printed substrate 2 that is illuminated (that is, the reflected light from the portion) And the control device 6 for performing various control, image processing, and calculation processing in the substrate inspection device 1 such as driving control of the illumination device 4 or the camera 5. The control device 6 constitutes an image acquisition means and an image processing means in the present embodiment.

Motors 15 and 16 are provided on the mounting table 3, and the motors 15 and 16 are driven and controlled by the control device 6, so that the printed circuit board 2 placed on the mounting table 3 is oriented in an arbitrary direction (X-axis direction and Y-axis direction). )slide.

The illuminating device 4 includes a light source 4a that emits a predetermined light, and a liquid crystal grid 4b that converts light from the light source 4a into a light pattern having a sinusoidal (striped) light intensity distribution, which can be applied to the printed substrate 2 A plurality of stripe-shaped light patterns of phase change are irradiated obliquely from above.

More specifically, in the illumination device 4, the light emitted from the light source 4a is guided by an optical fiber to a pair of condenser lenses, where it becomes parallel light. Its parallel light is guided to the projection lens via the liquid crystal grid 4b. Then, the printed circuit board 2 is irradiated with a stripe-shaped light pattern from the projection lens.

The liquid crystal grid 4b includes a common electrode in which a liquid crystal layer is formed between a pair of transparent substrates and disposed on a transparent substrate, and a strip electrode which is aligned in parallel with another transparent substrate, and is driven by a driving circuit. Switching elements (thin film transistors, etc.) respectively connected to the respective strip electrodes are subjected to on-off control, and the light transmittance of each of the grid lines corresponding to each strip electrode is switched by controlling the voltage applied to each strip electrode. A stripe-shaped grid pattern composed of a "bright portion" having a high light transmittance and a "dark portion" having a low light transmittance is formed. Then, it is irradiated onto the printed substrate 2 via the liquid crystal grid 4b. The light system on the light is a light pattern having a sinusoidal light intensity distribution depending on the blurring of the diffraction action or the like. Further, the grid pattern in the liquid crystal grid 4b is switched and controlled by the control device 6 (grid control means).

The camera 5 is constituted by a lens, an imaging element, or the like. In terms of imaging elements, a CMOS sensor is used. Of course, the imaging element is not limited to this, and for example, a CCD sensor or the like can also be used.

The image data captured by the camera 5 is converted into a digital signal by the camera 5, and then input to the control device 6 as a digital signal and stored in the image data storage device 24 to be described later. Next, the control device 6 performs image processing, inspection processing, and the like which will be described later based on the image data.

Next, the electrical configuration of the control device 6 will be described. As shown in FIG. 2, the control device 6 includes a CPU that controls the entire substrate inspection device 1 and an input/output interface 21 (hereinafter referred to as "CPU 21"); and a keyboard, a mouse, or a touch panel. An input device 22 as an "input means"; a display device 23 as a "display means" having a display screen such as a CRT or a liquid crystal; and an image data storage device 24 for storing image data captured by the camera 5; The calculation result memory device 25 that memorizes various calculation results; and the setting data storage device 26 for pre-remembering various information such as cover data (design data) or correction data to be described later. Further, each of the devices 22 to 26 is electrically connected to the CPU 21 or the like.

Next, the inspection procedure of the printed substrate 2 of the substrate inspection apparatus 1 will be described in detail. First, the correction to be performed before starting the inspection of the printed substrate 2 will be described. The correction system is used to grasp the unevenness (phase distribution) of the light pattern.

In the liquid crystal grid 4b, the voltage applied to each of the strip electrodes is uneven due to the variation in characteristics (offset amount, gain, etc.) of the respective transistors connected to the respective strip electrodes. Therefore, even in the same "bright portion" or "dark portion", the light transmittance (luminance level) of each line corresponding to each strip electrode becomes uneven. As a result, the light pattern irradiated onto the object to be measured does not have a sinusoidal ideal light intensity distribution, and there is a possibility that an error occurs in the three-dimensional measurement result.

Then, the so-called correction or the like in which the unevenness (phase distribution) of the light pattern is grasped in advance is performed.

In terms of the order of correction, first, a reference plane different from the height position of the printed substrate 2 and having a plane is prepared. The reference surface is the same color as the solder paste as the measurement object. That is, the reflectance of the solder paste and the light pattern become equal.

Next, by irradiating the reference surface with a light pattern and taking the reflected light by the camera 5, image data containing the luminance values of the respective coordinates is obtained. In the present embodiment, when the correction is performed, the phase of the light pattern is shifted by 90 degrees, and four types of image data respectively captured under each light pattern are obtained.

Then, the control device 6 calculates the phase θ of the light pattern in each pixel (coordinate) from the above-described four kinds of video data, and stores this as correction data in the setting data storage device 26.

Further, in the present embodiment, the gain A and the shift amount B of the light pattern in each pixel are specified from the above-described four kinds of video data, and the relationship between the two (see FIGS. 3 and 4) is used as the correction data. It is stored in the setting data memory device 26.

Here, the order of calculating the gain A and the offset B will be described in more detail. The relationship between the luminance values (V ₀ , V ₁ , V ₂ , and V ₃ ) of each of the four types of video data and the gain A and the offset B can be expressed by the following equations (H1), (H2), ( H3), (H4).

V ₀ =Asin θ +B‧‧‧(H1)

V ₁ =Asin( θ +90°)+B=Acos θ +B‧‧‧(H2)

V ₂ =Asin( θ +180°)+B=-Asin θ +B‧‧‧(H3)

V ₃ =Asin( θ +270°)+B=-Acos θ +B‧‧‧(H4)

Next, when the luminance values (V ₀ , V ₁ , V ₂ , and V ₃ ) of the four types of image data are added, the above equations (H1), (H2), (H3), and (H4) are organized as follows [ After the number 12], the following formula (H5) can be derived.

V ₀ +V ₁ +V ₂ +V ₃ =(Asin θ +B)+(Acos θ +B)+(-Asin θ +B)+(-Acos θ +B)=4B B=(V ₀ +V ₁ +V ₂ +V ₃ )/4‧‧‧(H5)

Further, the following formula (H6) can be derived from the above formulas (H1) and (H3).

According to V ₀ -V ₂ =2Asin θ, sin θ=(V ₀ -V ₂ )/2A‧‧‧(H6)

Further, the following formula (H7) can be derived from the above formulas (H2) and (H4).

According to V ₁ -V ₃ =2Acosθ, cos θ=(V ₁ -V ₃ )/2A‧‧‧(H7)

Then, as shown in the following [Number 15], when the above formulae (H6) and (H7) are substituted into the following formula (H8), the following formula (H9) can be derived.

1=sin ² θ +cos ² θ ‧‧‧(H8)

1={(V ₀ -V ₂ )/2A} ² +{(V ₁ -V ₃ )/2A} ²

4A ² =(V ₀ -V ₂ ) ² +(V ₁ -V ₃ ) ²

Where A>0

Then, the proportional constant K of the gain A and the offset B is calculated from the following equation (H10) derived from the above equations (H5) and (H9).

Then, the gain A, the offset B, and the proportional constant K of the light pattern in each of the pixels calculated as described above are stored as correction data in the setting data storage device 26. Of course, it can also be constructed: only the proportional constant K memory is used as the correction data. Therefore, the relationship grasping means in the present embodiment is constructed by the above-described series of processing functions for determining the proportionality constant K.

Further, in the present embodiment, the configuration is based on four types of image data captured under four kinds of light patterns having a phase difference of 90°, but it is not limited thereto, and may be constructed, for example, based on Three kinds of image data taken under the three kinds of light patterns with different phases Line correction.

Further, it is also possible to construct a configuration in which the luminance of the light source is changed a plurality of times when the correction is performed. With this configuration, the dark current (offset amount) of the camera 5 shown by the following formula (28) can be obtained.

A=KB+C...(28)

Among them, A: gain, B: offset, C: camera dark current (offset), K: proportional constant.

Alternatively, the relationship between the gain A and the offset B is not obtained by the equation, but by creating a mathematical table and table data indicating the relationship between the gain A and the offset B, the gain A can be obtained. The offset B is obtained or the gain A is obtained from the offset B.

In addition, it is also possible to use a substitution correction instead of using four (or three) types of image data for each of the four (or three) phase-changing light patterns when performing another measurement (in actual measurement). The relationship between the gain A and the offset B (proportional constant K) is obtained.

Next, a description will be given of a condition setting process to be performed before starting the inspection of the printed substrate 2. The condition setting process is a predetermined determination condition to be referred to when the number of pieces of image data (the number of times of imaging) to be acquired (photographed) for each of the inspection areas (measurement areas) is determined in advance by the control device 6 that determines the image acquisition means. Therefore, the function setting means in the present embodiment is constituted by the function (including the input device 22 and the display device 23) of the control device 6 that executes the condition setting process.

As will be described later, the present embodiment is configured to include a solder paste that satisfies the determination condition set here in the inspection region, and to obtain a photograph of each of the first predetermined types of light patterns having four phase changes. On the other hand, in the case where the solder paste which satisfies the above-described determination condition is not contained in the inspection area, two kinds of images which are respectively photographed under the second predetermined number of light patterns of two kinds of phase changes are obtained. video material.

The condition setting processing in the present embodiment is performed via the condition setting screen 230 (see FIG. 5) displayed on the display device 23. The condition setting screen 230 is provided with a plurality of item fields that can be set as the determination conditions.

More specifically, there is an "attribute" item column 231, which can set the electronic component to be soldered to a predetermined type as one of the determination conditions; the "volume" item column 232 can make the volume of the solder paste smaller than The predetermined value is one of the determination conditions; the "area" item column 233 can set the area of the solder paste to be less than a predetermined value as one of the determination conditions; the "circumference length" item column 234 can make the circumference of the solder paste smaller than The predetermined value is set as one of the determination conditions; and the "short side length" item column 235 can set one of the determination conditions as the short side length of the solder paste is less than a predetermined value.

In each of the item fields 231 to 235, a check box 236 for selecting an item thereof is provided. In the present embodiment, for example, "attribute" and "volume" can be combined to select a plurality of items. However, in the present embodiment, when a plurality of items (conditions) are selected, if any one of the items is satisfied, the configuration of the determination condition (so-called OR condition) is satisfied. Of course, instead of creating a plurality of items (conditions), it is a configuration that satisfies the determination condition (so-called AND condition).

The type of the electronic component as the determination condition in the "attribute" item column 231 includes an SOP (Small Outline Package) and a SOJ (Small Outline J-leaded; J-shaped outline). Structure), SOT (Small Outline Transistor), QFP (Quad Flat Package), PLCC (Plastic leaded chip carrier), BGA (Ball grid array; ball) Grid array). Needless to say, the type of the electronic component as the determination condition is not limited thereto. For example, other types such as LGA (Land grid array) can be used as the determination conditions.

Further, in the "attribute" item column 231, a check box 237 for selecting these varieties corresponding to each type of electronic component is provided. The electronic component of the predetermined type selected in the check box 237 is set as one of the determination conditions, and is stored in the setting data storage device 26.

In addition, the check box 237 of each item is placed in the check box 236 of the "Properties" item column 231, and the check box is selected to be input (optional) by selecting the "attribute" item. Further, in the present embodiment, for example, "SOP" and "SOJ" can be selected at the same time. However, in the present embodiment, when a plurality of varieties (conditions) are selected, if any one of the varieties is satisfied, the configuration of the determination condition (so-called OR condition) is satisfied.

On the other hand, in each of the item fields 232 to 235 of "volume", "area", "surrounding length", and "short side length", an input field 238 for inputting a numerical value to be a determination condition is provided. Here, the value of the input field 238 is set as one of the determination conditions, and is stored in the setting data storage device 26. In addition, each input field 238 is checked in the check box 236 of each corresponding item column 232-235, and the input (optional) value is started by selecting the item.

For example, in the case where "the volume" is less than "1 mm ³ " is set as the determination condition, the case where the "volume" is less than "1 mm ³ " is included in the inspection area. On the other hand, the image data was obtained by the four-shot method, and the image data was acquired by the two-shot method in the case where the "volume" was less than "1 mm ³ " in the inspection area.

Next, the inspection procedure performed for each inspection area will be described in detail with reference to the flowchart of FIG. 6. This inspection program is executed by the control device 6 (CPU or the like 21).

The control device 6 first drives the control motors 15 and 16 to move the printed circuit board 2, and aligns the field of view of the camera 5 with a predetermined inspection area on the printed circuit board 2. In addition, the inspection area is one area in which the surface of the printed circuit board 2 is previously divided by one field of view of the camera 5.

Next, in step S101, it is determined whether or not the solder paste satisfying the predetermined determination condition (for example, the volume is smaller than a predetermined value) set by the condition setting processing is included in the inspection region. The determination here is made with reference to the pre-memorized cover data.

The cover material stores, for example, a pad provided on the printed circuit board 2, and a position, a size, a shape, and the like of an ideal solder paste printed on the pad, and memorizes the electronic component to which the pad or solder paste belongs. Variety and so on.

Here, in the case where the solder paste satisfying the above-described determination condition is included in the inspection region, the process proceeds to step S102, and the image data is acquired by the four-time imaging method for the inspection region. In other words, four kinds of image data obtained by irradiating the light patterns in four kinds of phases are obtained.

More specifically, the control device 6 first switches the control lighting device The liquid crystal grid 4b of the fourth liquid crystal grid 4b sets the position of the grid formed on the liquid crystal grid 4b at a predetermined reference position (a position of phase "0°").

When the switching setting of the liquid crystal grid 4b is completed, the control device 6 starts the first imaging process under the light pattern of the phase "0°" at a predetermined timing Ta1 (see FIG. 8(a)).

Specifically, the light source 4a of the illumination device 4 is caused to emit light, the illumination of the light pattern is started, and the camera 5 is driven to start photographing the portion of the inspection region illuminated by the light pattern. The procedure of this photographing process is also the same in the second to fourth photographing processes to be described later.

Next, the control device 6 ends the first imaging process at the timing Ta2 after a predetermined time (10 msec in the present embodiment) from the start of imaging. That is, the irradiation of the light pattern is ended, and the first shot related to the light pattern is ended. Here, the image data taken by the camera 5 is transferred to the image data storage device 24 and memorized (the same applies hereinafter).

At the same time, the control device 6 starts the switching process of the liquid crystal grid 4b of the illumination device 4 at the timing Ta2. Specifically, the position of the grid formed on the liquid crystal grid 4b is shifted from the reference position (the position of the phase "0°") toward the phase of the light pattern by the phase "90°" of the interval of one-fourth of the interval. The process of switching is performed.

Then, the control device 6 terminates the switching process at a timing Ta3 after a predetermined time (20 msec in the present embodiment) from the start of the switching process of the liquid crystal grid 4b (timing Ta2).

While the switching process of the liquid crystal grid 4b is completed, the control device 6 starts the second imaging process below the light pattern of the phase "90°" at the timing Ta3, and the predetermined time elapses from the start of imaging (in the present embodiment) At the timing Ta4 after 10 msec), the second shooting process is ended.

At the same time as the completion of the second imaging process, the control device 6 starts the switching process of the liquid crystal grid 4b of the illumination device 4 at the timing Ta4. Specifically, the position of the grid formed on the liquid crystal grid 4b of the illumination device 4 from the position of the phase "90°" toward the phase of the light pattern is shifted by a phase of "one-eighth" of the phase "180°". The process of switching is performed.

While the switching process of the liquid crystal grid 4b is completed, the control device 6 starts the third imaging process below the light pattern of the phase "180°" at the timing Ta5, and the predetermined time elapses from the start of imaging (in the present embodiment) At the timing Ta6 after 10 msec), the third shooting process is ended.

At the same time, the control device 6 starts the switching process of the liquid crystal grid 4b of the illumination device 4 at the timing Ta6. Specifically, the position of the grid formed on the liquid crystal grid 4b is switched from the position of the phase "180°" to the position of the phase of the light pattern shifted by one-fourth of the interval "270°". .

Then, the control device 6 ends the switching process by the timing Ta7 after the switching process of the liquid crystal grid 4b (timing Ta6) has elapsed for a predetermined time (20 msec in the present embodiment).

While the switching process of the liquid crystal grid 4b is completed, the control device 6 starts the fourth imaging process below the light pattern of the phase "270°" at the timing Ta7, and the predetermined time elapses from the start of imaging (in the present embodiment) At the timing Ta8 after 10 msec), the fourth shooting process is ended.

In this manner, by performing the series of photographing processes described above, image data of four screen sizes captured under four kinds of phase-change light patterns are obtained.

On the other hand, in step S101, if the solder paste satisfying the above-described determination condition is not included in the discrimination inspection region, the process proceeds to step S103, and the image data is acquired by the secondary imaging method for the inspection region. In other words, two types of image data obtained by irradiating two types of phases and photographing a light pattern are obtained.

More specifically, the control device 6 first switches the liquid crystal grid 4b that controls the illumination device 4, and sets the position of the grid formed on the liquid crystal grid 4b at a predetermined reference position (a position of phase "0°").

When the switching setting of the liquid crystal grid 4b is completed, the control device 6 starts the first imaging processing under the light pattern of the phase "0°" at a predetermined timing Tc1 (see FIG. 8(c)).

Specifically, the light source 4a of the illumination device 4 is caused to emit light, the illumination of the light pattern is started, and the camera 5 is driven to start photographing the portion of the inspection region to which the light pattern is irradiated. The procedure of this photographing process is also the same in the second photographing processing to be described later.

Next, the control device 6 ends the first imaging process at the timing Tc2 after a predetermined time (10 msec in the present embodiment) from the start of imaging. That is, the irradiation of the light pattern is ended, and the first shot related to the light pattern is ended. Here, the image data taken by the camera 5 is transferred to the image data storage device 24 and memorized (the same applies hereinafter).

At the same time, the control device 6 starts the switching process of the liquid crystal grid 4b of the illumination device 4 at the timing Tc2. Specifically, the position of the grid formed on the liquid crystal grid 4b is shifted from the reference position (the position of the phase "0°") toward the phase of the light pattern by the phase "180°" of the interval of one-half of the interval. The process of switching is performed.

Then, the control device 6 ends the switching process after the predetermined time (20 msec in the present embodiment) from the start of the switching process of the liquid crystal grid 4b (timing Tc2).

While the switching process of the liquid crystal grid 4b is completed, the control device 6 starts the second imaging process below the light pattern of the phase "180°" at the timing Tc3, and the predetermined time elapses from the start of imaging (in the present embodiment) At the timing Tc4 after 10 msec), the second shooting process is ended.

In this way, by performing the above-described series of photographing processes, image data of two screen sizes captured under two kinds of phase-changing light patterns are obtained.

Specific examples are given here for explanation. For example, in the printed circuit board 2 illustrated in FIG. 7 , a small-sized pad (not shown) of an electronic component such as a BGA or SOP or QFP that is a predetermined determination condition is printed in a small size. The solder paste Js is printed with a solder paste Jb of a larger size in correspondence with a large-sized pad (not shown) of an electronic component such as a resistor or a capacitor or a transistor.

Therefore, the printed circuit board 2 includes only the inspection region W1 of the solder paste Js having a small size satisfying the predetermined determination condition, and the solder paste Js having a smaller size satisfying the above-described determination conditions, and the above-mentioned determination conditions are not satisfied. The inspection area W2 of the larger-sized solder paste Jb is obtained by using four times of shooting. On the other hand, the inspection areas W3 and W4 of the solder paste Jb having a large size that does not satisfy the above-described determination conditions are contained in the solder paste Js which does not satisfy the above-described determination condition, and the image is acquired by the second shot method. data.

Next, the control device 6 is in step S104, according to the above The image data obtained in step S102 or step S103 is subjected to three-dimensional measurement (height measurement) by a phase shift method.

First, the case where four types of video data are acquired in step S102 will be described. The control device 6 calculates the phase θ ₁ of the light pattern of each pixel from the above-described four kinds of video data (luminance values of the respective pixels) by the phase shift method.

Here, the luminance values V ₁₀ , V ₁₁ , V ₁₂ , and V ₁₃ of the respective pixels of the above-described four types of video data can be expressed by the following equations (H1 ' ), (H2 ' ), (H3 ' ), ( H4 ' ) indicates. Brightness values of each pixel of four kinds of image data

V ₁₀ =Asin θ ₁ +B‧‧‧(H1')

V ₁₁ =Asin( θ ₁ +90°)+B=Acos θ ₁ +B‧‧‧(H2')

V ₁₂ =Asin( θ ₁ +180°)+B=-Asin θ ₁ +B‧‧‧(H3')

V ₁₃ =Asin( θ ₁ +270°)+B=-Acos θ ₁ +B‧‧‧(H4')

Where A: gain, B: offset

When the above formula (H1 '), (H2' ), (H3 '), (H4') to solve for the phase θ _1, can be derived by the following formula (H11).

θ ₁ =tan ^-1 {(V ₁₀ -V ₁₂ )/(V ₁₁ -V ₁₃ )}‧‧(H11)

Next, the control device 6 compares the phase θ ₁ of each pixel calculated as described above with the correction data stored in the set data storage device 26 (based on the phase of each pixel corrected), and calculates pixels having the same phase. The offset amount is calculated based on the triangulation principle, and the height data (z) of each pixel (x, y) of the inspection region is calculated, and the height data (z) is stored in the calculation result memory device 25.

For example, when the measured value (phase) in the measured pixel (x, y) is "10°", the value of "10°" is detected. Which position on the data of the memory. Here, if "10°" exists in three pixels adjacent to the pixel (x, y) to be measured, it means that the stripe of the light pattern is shifted by three pixels. Further, the height data (z) of the measured pixel (x, y) can be obtained by the triangulation principle according to the irradiation angle of the light pattern and the offset amount of the stripe of the light pattern.

Next, a case where two kinds of video data are acquired in step S103 will be described. The control device 6 calculates each of the two kinds of video data (the luminance value of each pixel) and the correction data (based on the corrected proportional constant K of each pixel) of the above-described setting data storage device 26 by the phase shift method. The phase θ ₂ of the light pattern of the pixel.

Here, in the case where the luminance values V ₂₀ and V ₂₁ of the respective pixels of the two kinds of video data are set, the phase θ ₂ of the light pattern of each pixel can be expressed by the following formula (H12) according to the above formula (15). ) said.

θ ₂ =sin ^-1 [(V ₂₀ -V ₂₁ )/K(V ₂₀ +V ₂₁ )]...(H12)

Where K: the proportional constant.

Next, the control device 6 compares the phase θ ₂ of each pixel thus calculated with the correction data stored in the set data storage device 26 (based on the phase of each pixel corrected), and calculates the same phase. The offset of the pixel is calculated based on the triangulation principle, and the height data (z) of each pixel (x, y) of the inspection region is calculated, and the height data (z) is stored in the calculation result memory device 25.

Next, in step S105, the control device 6 performs the solder paste quality determination process based on the three-dimensional measurement result (the height data of each coordinate) in the above step S104. Specifically, the control device 6 detects the solder paste higher than the reference surface based on the measurement result of the inspection region obtained as described above. The printing range is calculated by integrating the heights of the respective parts in the range to calculate the amount of solder paste to be printed.

Next, the control device 6 compares the data such as the position, area, height, or amount of the solder paste thus obtained with the reference data (cover data, etc.) stored in advance in the setting data storage device 26, and accordingly, whether the comparison result is Within the allowable range, it is judged whether or not the printed state of the solder paste in the inspection area is good or not.

While this process is being performed, the control device 6 drives the control motors 15 and 16 to move the printed circuit board 2 toward the next inspection region. Thereafter, the series of processes are repeatedly performed in all the inspection regions, and the entire printed circuit board 2 is finished. an examination.

As described in detail above, according to the present embodiment, the image data is acquired by the four-shot method and the three-dimensional measurement is performed with high precision, and the inspection region including the solder paste that satisfies the predetermined determination condition (for example, the size is smaller than the predetermined value). On the other hand, in the inspection area other than the inspection area, the three-dimensional measurement can be performed in a shorter time by acquiring the image data by the two-time imaging method.

As a result, in the three-dimensional measurement by the phase shift method, it is possible to maintain the measurement accuracy necessary for the solder paste (the solder paste requiring high-precision measurement) that satisfies the predetermined determination conditions and to increase the measurement speed.

Further, in the present embodiment, the relationship between the gain A and the offset B determined by the predetermined imaging conditions is used for the inspection region in which the solder paste that does not satisfy the predetermined determination condition is included (for example, A = K (proportional constant) ) × B] and the gain A(x, y) or offset of the pixel (x, y) determined by the luminance value V(x, y) of each pixel (x, y) on the image data. B(x,y) value According to the image data obtained by the two-time shooting method and the height measurement by the phase shift method.

Thereby, it is possible to shorten the time required until the end of all the photographing processing (final photographing processing) up to the predetermined inspection area. As shown in Fig. 8(c), in the case of the secondary imaging method, the time required until the end of all the imaging processing in the predetermined inspection area is [the time required for the imaging processing [10 ms] × 2 times] + [Time required for switching processing of the liquid crystal grid 4b [20 ms] × 1 time] = total [40 msec].

[Second Embodiment]

Hereinafter, the second embodiment will be described with reference to the drawings. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the first embodiment described above, the relationship between the gain A and the offset B of the light pattern in each pixel (proportional constant K) is transmitted in advance (four images are taken under the light patterns of the four phase changes). Instead, the second embodiment is constructed such that the relationship between the gain A of the light pattern and the offset B (proportional constant K) is measured by the second-time imaging method ( In actual measurement, it is obtained based on two types of image data taken under two kinds of phase-changing light patterns.

In terms of the order, the offset B is first obtained for the full pixel of the image data using the above formula (12). Next, the luminance value V (= Asin θ + B) of the pixel in which the value of the offset B is uniform is extracted, and a histogram is created. An example of this is shown in the tables of Figs. In addition, FIGS. 9 and 10 illustrate a case where the gain A is set to "1" and the offset amount B is set to "0". Figure 9 is a data interval in which the luminance value V is divided into "0.1" widths, indicating the data. A distribution table of the number of luminance values included in the interval, and FIG. 10 is a histogram plotted.

Next, the maximum value V _{MAX of the} luminance value and the minimum value V _{MIN are} determined according to the histogram. By using the characteristic of "sin θ", the two peaks generated in the above histogram can be determined as the maximum value V _MAX and the minimum value V _MIN of the luminance value, respectively. In the example shown in FIGS. 9 and 10, the number of luminance values V in the data interval in which the luminance value V has entered "-1.0 to -0.9" and "0.9 to 1.0" is "51", and becomes two here. crest.

Next, the gain A and the offset B are calculated based on the maximum value V _{MAX of the} luminance value and the minimum value V _MIN . As described above, the average value of the maximum value V _MAX and the minimum value V _MIN of the luminance value becomes the offset amount B, and half of the difference between the maximum value V _MAX and the minimum value V _MIN becomes the gain A. That is, as shown in FIG. 9, the intermediate value of the two peaks is the offset B, and the half of the width of the two peaks becomes the gain A.

The proportional constant K can be determined based on the values of the gain A and the offset B thus obtained (refer to the above formula (3)). Therefore, the relationship grasping means in the present embodiment is constructed by the above-described series of processing functions for determining the proportionality constant K.

According to this embodiment, the same operational effects as those of the first embodiment described above can be achieved. Further, the correction work as in the first embodiment described above can be omitted, and the measurement time can be further shortened.

Further, in the present embodiment, the video data of the two types of light images captured under the two types of light patterns having a phase difference of 180° are obtained, and the proportional constant K and the like are obtained for the full pixels of the image data. Due to this limitation, it can also be constructed: for example, according to two kinds of light patterns with a phase difference of 90°. The two types of image data taken below are used to obtain a proportional constant K and the like. Further, it is also possible to construct a proportional constant K or the like in a range of a part of the image data such as the periphery of the pixel to be measured, not in the full pixel of the image data.

Further, it is not limited to the description of the above embodiment, and may be implemented, for example, as follows. Of course, other application examples and modifications not illustrated below may be used.

(a) In the above embodiment, the three-dimensional measuring device is embodied as a substrate inspecting device 1 for measuring the height of the solder paste formed on the printed circuit board 2. However, the present invention is not limited thereto, and may be embodied, for example. The height of the solder bump printed on the substrate or the electronic component mounted on the substrate is measured.

(b) In the above embodiment, the grid for converting the light from the light source 4a into the stripe pattern is formed by the liquid crystal grid 4b, and the phase of the light pattern is controlled by switching control thereof. The composition of the offset. However, it is not limited thereto, and it is also possible to transfer the grating member by a transfer means such as a piezoelectric actuator to shift the phase of the light pattern.

(c) In the above-described embodiment, the inspection area including the solder paste satisfying the predetermined determination condition is based on four types of image data captured under four kinds of light patterns having a phase difference of 90 degrees. In the three-dimensional measurement, the inspection area of the solder paste which does not satisfy the above-described determination conditions is subjected to three-dimensional measurement based on two kinds of image data respectively taken under two kinds of light patterns having a phase difference of 180°.

Without being limited to this, it is also possible to construct, for example, four types of image data which are respectively photographed under four kinds of light patterns having a phase difference of 90° for an inspection region containing a solder paste satisfying a predetermined determination condition. Enter Three-dimensional measurement, three-dimensional measurement based on three types of image data taken under three kinds of light patterns with 120° (or 90°) phase difference for an inspection area that does not contain the solder paste satisfying the above-mentioned determination conditions .

Further, it is also possible to construct three kinds of image data which are respectively photographed under three kinds of light patterns having a phase difference of 120 (or 90) for an inspection region containing a solder paste satisfying a predetermined determination condition. Three-dimensional measurement is performed, and three-dimensional measurement is performed on two types of image data taken under two kinds of light patterns having 180° (or 90°) phase difference for an inspection area that does not contain the solder paste satisfying the above-described determination conditions. .

Of course, the phase shift amount is not limited by the various offsets exemplified above, and other offsets that can be three-dimensionally measured by the phase shift method can also be used.

(d) In the above-described embodiment, the inspection region including the solder paste that satisfies the predetermined determination condition is three-dimensionally measured by the four-shot imaging method, and the inspection region that does not contain the solder paste that satisfies the above-described determination condition is used. In the case of performing the three-dimensional measurement in the two-shot mode, the shooting mode is switched in two stages, but it is not limited thereto, and the shooting mode can be switched in three stages.

For example, a condition setting screen 330 shown in FIG. 11 may be used, and a specific condition (for example, a condition set in the medium accuracy measurement column 331 in FIG. 11) that satisfies a predetermined determination condition (for example, a condition set in the middle accuracy measurement column 331 in FIG. 11) is included in the inspection area (for example, In the case of the solder paste in the condition set by the high-precision measurement column 332 in FIG. 11 , four kinds of image data are acquired by four imaging methods (four kinds of phase irradiation and imaging light pattern), and are in the inspection area. Contains solder paste that satisfies the above-mentioned determination conditions but does not contain solder paste that satisfies the aforementioned specific conditions In the case of three types of image data (three kinds of phase irradiation and photographing light pattern), three kinds of image data are obtained, and in the inspection area, the solder paste that satisfies the above-described determination condition is not included, and the two-time imaging method is used. Two kinds of phase illumination and photographing light patterns are used to obtain two types of image data.

For example, in the case where "volume is less than "2mm ³ " is set to "judgment condition", "volume is less than "1mm ³ "" is set to "specific condition", and "volume" is When the solder paste of less than "1mm ³ " is not included in the inspection area, the image data is acquired by four shots, and the solder paste containing "the volume" is less than "2mm ³ " is included in the inspection area but does not contain When the "volume" is less than "1mm ³ ", the image data is obtained by three shots, and the solder paste that satisfies "the volume is less than "2mm ³ " is not included in the inspection area. In the case, the image data is obtained by using two shooting methods.

(e) In the above-described embodiment, the inspection area is included in the solder paste (for example, the solder paste Js of FIG. 7) that satisfies the determination condition and the solder paste (for example, the solder paste Jb of FIG. 7) that does not satisfy the determination condition ( For example, in the inspection area W2 of FIG. 7 , in the case of four kinds of image data captured under four kinds of light patterns having different phases, two solder pastes in the inspection area (for example, the welding of FIG. 7 ) The pastes Js and Jb) are based on four kinds of image data for three-dimensional measurement.

Without being limited thereto, it is also possible to construct, for example, an inspection for both a solder paste (for example, solder paste Js of FIG. 7) satisfying the determination condition and a solder paste (for example, solder paste Jb of FIG. 7) that does not satisfy the determination condition. In the region (for example, the inspection region W2 in FIG. 7), in the case where four kinds of image data respectively captured under four kinds of light patterns having different phases are obtained, the inspection region is full. The solder paste for the determination condition (for example, the solder paste Js of FIG. 7) is three-dimensionally measured based on the four types of image data, and the solder paste (for example, the solder paste Jb of FIG. 7) that does not satisfy the determination condition in the inspection area is used. Two or three kinds of image data of four types of image data were taken for three-dimensional measurement.

According to this configuration, for the solder paste that does not satisfy the predetermined determination condition (the measurement accuracy does not require such a degree of solder paste), the three-dimensional measurement can be performed in a shorter time based on less image data. As a result, it is possible to further increase the measurement speed.

In addition, in the case of obtaining four kinds of video data, the measurement accuracy of the solder paste (for example, the solder paste Jb of FIG. 7) that does not satisfy the predetermined determination condition can be used, and the second or third shot can be used according to the use. In the case of performing three-dimensional measurement of two or three kinds of image data obtained by the method, the measurement accuracy of the solder paste (for example, the solder paste Jb of FIG. 7) that does not satisfy the predetermined determination conditions is equivalent.

Of course, for an inspection region including a solder paste (for example, solder paste Js of FIG. 7) satisfying the determination condition and a solder paste (for example, solder paste Jb of FIG. 7) that does not satisfy the determination condition (for example, inspection region W2 of FIG. 7) The same configuration may be employed in the case of obtaining three types of image data respectively captured under three kinds of light patterns having different phases.

Further, in a configuration in which the imaging method exemplified in the above (d) is switched in three stages, when four kinds of video data are acquired by four imaging methods, specific conditions are satisfied in the inspection area ( For example, the "volume" is less than "1mm ³ ".) The three-dimensional measurement is performed by the phase shift method based on the four kinds of image data. The specific conditions are not met in the inspection area and the judgment conditions are satisfied (for example, "volume" Solder paste which is less than "2mm ³ ")), based on the image data of three of the four kinds of image data obtained, three-dimensional measurement by the phase shift method, and the solder paste which does not satisfy the above-mentioned determination conditions in the inspection area is based on The image data of two of the four kinds of image data obtained are three-dimensionally measured by the phase shift method, and three types of image data are obtained by three times of shooting, and the solder paste that satisfies the above-described determination conditions in the inspection area is used. According to the three kinds of image data, the three-dimensional measurement is performed by the phase shift method, and the solder paste that does not satisfy the above-mentioned determination conditions in the inspection area is based on two kinds of images of the three types of image data obtained. Material dimensional measurement method using a phase shift.

(f) In the above-described embodiment, the determination condition is set on the transmission condition setting screen 230, but the configuration of the condition setting means is not limited thereto.

It is also possible to construct a determination condition by, for example, the condition setting screen 350 shown in FIG. In the condition setting screen 350, by sliding the slide bar 351 to the left and right, the volume value of the solder paste as the determination condition can be changed. In addition, the slider 351 is an image simulating the slider displayed on the display device 23, and is operable through the touch panel.

Here, the inspection region of the solder paste containing the volume smaller than the predetermined value set by the operation slider 351 is three-dimensionally measured by the four-shot imaging method, and is used for the inspection region of the solder paste not containing the volume smaller than the predetermined value. 2 shots for 3D measurement.

In FIG. 12, for example, when the slide bar 351 is moved to the right end, the volume value of the solder paste as a determination condition becomes the maximum value. In other words, all of the solder paste on the printed circuit board 2 satisfies the determination condition, and three-dimensional measurement is performed by four imaging methods for all the inspection regions. On the other hand, when When the slider 351 is moved to the left end, the volume value of the solder paste as a determination condition becomes the minimum value. In other words, all of the solder paste on the printed circuit board 2 does not satisfy the determination condition, and three-dimensional measurement is performed by using two imaging methods for all the inspection regions.

Further, the condition setting screen 350 is provided with a predetermined time display unit 352 (predetermined time display means) which can display the measurement of the printed substrate 2 under the determination condition (scheduled volume value) set by the operation slider 351. scheduled time. The predetermined time displayed here is calculated based on the determination conditions set by the operation slider 351 and the cover data.

For example, in the example shown in FIG. 8, the time required for the completion of all the imaging processes up to one inspection area is 100 msec (0.100 sec) in the case of the four imaging modes, and the case of the two imaging modes is 40msec (0.040sec).

Therefore, when the number of inspection areas set on the printed circuit board 2 is N, the time required to obtain the entire range of video data of one printed circuit board 2 is obtained by using four imaging methods for all the inspection areas. In the case of image data, it becomes 100 × N (msec). On the other hand, when image data is acquired by using two imaging methods for all the inspection areas, it is 40 × N (msec).

Further, the number of inspection regions of the solder paste having the volume of the solder paste having a volume smaller than a predetermined value set by the operation slider 351 is N1 (number), and the number of inspection regions of the solder paste not containing the volume smaller than the predetermined value is N2 ( In the case of obtaining image data of the entire range of one printed substrate 2, the time required to obtain the entire range of image data of one printed substrate 2 is 100 × N1 (msec) + 40 × N2 (msec).

Furthermore, it can also be constructed by driving the motors 15, 16 and The time including the moving time for moving the printed substrate 2 from the predetermined inspection region toward the next inspection region is displayed on the predetermined time display portion 352 as a predetermined time.

(g) In the above-described embodiment, the two-dimensional imaging method performs three-dimensional measurement based on two types of image data captured under two types of light patterns having a phase difference of 180 degrees. Alternatively, for example, three-dimensional measurement may be performed based on two kinds of image data respectively captured under two kinds of light patterns having a phase difference of 90°. In this case, by using the above equations (23) and (27), the luminance values V ₂₀ and V ₂₁ of the respective pixels on the two kinds of video data and the known proportional constant K can be used to calculate each pixel. The phase θ ₂ of the light pattern.

According to this configuration, since the phase θ ₂ can be obtained based on the calculation formula using "tan ^-1 ", the height measurement can be performed in the 360° range of -180° to 180°, and the measurement range can be made larger.

Of course, in addition to this, if the relationship of the above formulas (1), (2), and (3) is satisfied, other configurations may be employed. In the general formula for obtaining the phase θ ₂ , the above formula (9) is exemplified [refer to [9]].

1‧‧‧Substrate inspection device

2‧‧‧Printing substrate

3‧‧‧ mounting table

4‧‧‧Lighting device

4a‧‧‧Light source

4b‧‧‧LCD grille

5‧‧‧ camera

6‧‧‧Control device

15‧‧‧Motor

16‧‧‧Motor

Claims (13)

A three-dimensional measuring apparatus comprising: an irradiation means for irradiating a light pattern having a stripe-shaped light intensity distribution on an object to be measured; and an imaging means capable of capturing a predetermined image on the object to be measured irradiated with the light pattern a measurement area; a video acquisition means configured to control the illumination means and the imaging means to change a plurality of phases of the light pattern, and to obtain a plurality of types of the measurement areas respectively captured under the light patterns Image, and the number of images to be obtained for the measurement area may be changed according to the measurement area; and the image processing means may use the phase shift method for the measurement object in the measurement area according to the image obtained by the image acquisition means The image acquisition means is configured to include the measurement target that satisfies a predetermined determination condition in the measurement region, and acquire the first predetermined number of the first predetermined number of phases and to capture the light pattern. The image does not contain the aforementioned measurement that satisfies the aforementioned determination conditions in the aforementioned measurement area. Where the object, to obtain first and second of less than the predetermined number of several predetermined phase of the irradiated light and the captured image obtained from said second predetermined number of patterns thereof. The three-dimensional measuring apparatus of claim 1, wherein the image acquiring means acquires the first predetermined number of images, In the image processing means, the measurement target that satisfies the determination condition in the measurement region performs three-dimensional measurement by the phase shift method based on the first predetermined number of images, and the measurement condition is not satisfied in the measurement region. The measurement object is subjected to three-dimensional measurement by a phase shift method based on the second predetermined number of images. The three-dimensional measuring apparatus according to claim 1, wherein the condition setting means capable of setting the aforementioned determination condition in accordance with an external operation is provided. The three-dimensional measuring apparatus according to claim 2, wherein the condition setting means capable of setting the aforementioned determination condition in accordance with an external operation is provided. The three-dimensional measuring apparatus according to claim 3, wherein the predetermined time display means is provided for displaying the predetermined time spent on the measurement of the object to be measured under the aforementioned determination condition set by the condition setting means. The three-dimensional measuring apparatus according to claim 4, further comprising predetermined time display means for displaying a predetermined time spent on the measurement of the object to be measured under the aforementioned determination condition set by the condition setting means. The three-dimensional measuring apparatus according to claim 1, wherein the image capturing means includes the measurement target that satisfies the determination condition in the measurement area, and the first predetermined number is four or three. The four or three types of images obtained by the phase irradiation and the light pattern are captured, and the measurement target that satisfies the above-described determination condition is not included in the measurement region, and two types of phase illumination are obtained in the second predetermined number. And take two kinds of images obtained by the light pattern. The three-dimensional measuring apparatus according to claim 2, wherein the image capturing means includes, in the measurement area, the measurement target that satisfies the determination condition, and obtains four or three types of phase irradiation in the first predetermined number In the case where the four or three types of images obtained by the light pattern are not included in the measurement region, the measurement target that satisfies the determination condition is not included, and the second predetermined number of phase illuminations are obtained and the light pattern is captured. Two kinds of images obtained. The three-dimensional measuring apparatus according to claim 3, wherein the image capturing means includes, in the measurement region, the measurement target that satisfies the determination condition, and obtains four or three types of phase irradiation in the first predetermined number In the case where the four or three types of images obtained by the light pattern are not included in the measurement region, the measurement target that satisfies the determination condition is not included, and the second predetermined number of phase illuminations are obtained and the light pattern is captured. Two kinds of images obtained. The three-dimensional measuring apparatus according to claim 4, wherein the image capturing means includes, in the measurement area, the measurement target that satisfies the determination condition, and obtains four or three types of phase irradiation in the first predetermined number And taking 4 or 3 kinds of images obtained by the light pattern, In the case where the measurement target that satisfies the above-described determination condition is not included in the measurement region, two kinds of images obtained by photographing the light pattern by the second predetermined number of phases are obtained. The three-dimensional measuring apparatus according to claim 5, wherein the image capturing means includes, in the measurement area, the measurement target that satisfies the determination condition, and obtains four or three types of phase irradiation in the first predetermined number. In the case where the four or three types of images obtained by the light pattern are not included in the measurement region, the measurement target that satisfies the determination condition is not included, and the second predetermined number of phase illuminations are obtained and the light pattern is captured. Two kinds of images obtained. The three-dimensional measuring apparatus according to claim 6, wherein the image capturing means includes, in the measurement area, the measurement target that satisfies the determination condition, and obtains four or three types of phase irradiation in the first predetermined number. In the case where the four or three types of images obtained by the light pattern are not included in the measurement region, the measurement target that satisfies the determination condition is not included, and the second predetermined number of phase illuminations are obtained and the light pattern is captured. Two kinds of images obtained. The three-dimensional measuring apparatus according to any one of claims 1 to 12, wherein the measuring object is a solder paste printed on a printed substrate as the object to be measured, or formed on a wafer substrate as the object to be measured Solder bumps.