JP5129689B2 - Printed solder inspection apparatus and printed solder inspection method - Google Patents

Description

  The present invention relates to a printed solder inspection apparatus and method for measuring and inspecting a solder formation state when cream-like solder is printed on a printed board for surface mounting electronic components and the like. In particular, a printed circuit board is a place where solder is printed (hereinafter referred to as a “solder place”), and a circuit pattern (pad) is revealed. There is a resist part (part where solder is not printed) coated with a resist that can transmit near-infrared light on the top. However, the present invention applies the displacement (height) of the actually printed solder to the lower part of the resist part. The present invention relates to a technique that can be measured as a height from a certain pad surface (circuit pattern surface).

  As a technique for measuring the height (displacement) of the solder from the pad surface, there is a technique of Patent Document 1 filed earlier by the present applicant. In the technique of Patent Document 1, the measurement point on the surface of the printed board is irradiated with visible light vertically, the first displacement of the printed board surface is obtained by the scattered light, the visible light is irradiated obliquely, and the regular reflected light is used. It is a displacement measuring device which calculates | requires 2nd displacement, selects either those 1st displacement or 2nd displacement, and measures the displacement of a measurement point. Specifically, the resist surface is measured in advance, and the relationship between the first displacement and the second displacement at that time and the thickness of the resist is stored as a function. When measuring the printed circuit board, the position of the pad surface under the resist is estimated from the thickness of the resist surface with reference to the above function based on the first displacement and the second displacement when the resist surface is irradiated. The first displacement and the second displacement at the solder location based on the position of the pad surface were obtained.

Japanese Patent Application No. 2007-284768

  Although the technique of the above-mentioned Patent Document 1 is measured with visible light, when visible light is irradiated almost perpendicularly to a translucent resist surface, a part of the resist is transmitted but a part of it is reflected. If only the reflected light of the transmitted light is grasped, the displacement of the lower pad surface can be measured, but since both the light reflected on the surface without transmitting and the light reflected and transmitted are taken in and measured, Thus, it is necessary to grasp the relationship between the reflection and the resist thickness in advance as a function.

  However, in subsequent tests, it was found that most of the resist surface is transmitted by irradiating the resist surface vertically with near infrared light instead of visible light, so that the displacement of the pad surface underneath can be measured. On the other hand, it was also found that when it was obliquely irradiated with near infrared light, it was almost reflected on the resist surface.

  That is, as shown in FIG. 4, a resist 1a and solder 1b are formed on a surface of a pad 1c (for example, a wiring pattern surface of a copper foil) stretched on a printed board 1 (hereinafter referred to as “substrate”). Has been. Even if the resist 1a is irradiated with near-infrared light obliquely as shown in FIG. On the other hand, when visible light is irradiated vertically as shown in FIG. 5B, there is reflection from both the surface of the resist 1a and the pad 1c as described above, but near red as shown in FIG. 5C. When vertically irradiated with external light, most of the light is transmitted and reflected by the pad 1c at the bottom. That is, it was found that the displacement (height) of the pad 1c under the resist 1a can be measured by vertical irradiation with near infrared light.

  An object of the present invention is to provide a printed solder inspection apparatus capable of measuring the displacement of a resist bottom by near infrared light and measuring the displacement (height) of solder with reference to the displacement of the bottom.

  In order to achieve the above-mentioned object, the invention according to claim 1 is characterized in that the perpendicular to the measurement point on the surface of the printed board having a solder spot where the solder is printed on the pad surface and a resist spot where the resist is applied. First sensing means (OS1, D1, D2) that irradiates near infrared light within a wavelength of 0.76 to 0.9 μm transmitted through the resist and receives scattered light from the measurement point, the same as the measurement point Displacement sensor (2) including second sensing means (OS2, D3) that irradiates the measurement point with the near-infrared light at an oblique angle with respect to the vertical and receives specularly reflected light at the measurement point. ), A data processing unit (3) for obtaining a displacement at each measurement point on the surface of the printed circuit board based on the output of the first sensing means, and luminance data based on the output of the second sensing means. In response to the measurement point determination unit (5) for identifying whether the measurement point is a solder location or a resist location, and the displacement obtained by the identification result and the data processing unit, the resist location is defined as a measurement point. And a measurement calculation unit (7) for determining the height of the solder spot with respect to the pad surface at the bottom of the resist spot.

  According to a second aspect of the present invention, in the first aspect of the invention, the first sensing unit outputs luminance data of a measurement point, and the measurement point determination unit includes the luminance data of the first sensing unit. And the measurement point identifies the solder location and the pad at the bottom of the resist by comparing with the threshold value stored in advance based on the luminance data of the second sensing means, The height of the solder spot from the pad surface is obtained based on the identification result and the displacement obtained by the data processing unit.

  The invention according to claim 3 has a wavelength of 0.76 to a wavelength at which the resist transmits perpendicularly to a measurement point on the surface of the printed board having a solder portion where the solder is printed on the pad surface and a resist portion where the resist is applied. First sensing means (OS1, D1, D2) that irradiates near-infrared light within 0.9 μm and receives scattered light from the measurement point, and a predetermined angle with respect to the perpendicular to the same measurement point as the measurement point A displacement sensor (2) including second sensing means (OS2, D3) that receives the specularly reflected light that is irradiated with the near-infrared light at an oblique angle and specularly reflected at the measurement point; and the second sensing means A measurement point determination unit (5) for identifying at least the measurement point as a solder location or a resist location based on luminance data based on the output of the output, receiving the identification result, and using the registration location as a measurement point Measurement point The displacement of the pad surface is calculated based on the output of the first sensing means when the scattered light from the pad surface at the bottom is received, and further the scattering from the solder location using the solder location as a measurement point And a displacement measuring unit (100) for determining the height of the solder spot from the pad surface based on the output of the first sensing means when receiving light.

  The invention according to claim 4 has a wavelength of 0.76 to 0.7 at which the resist transmits perpendicularly to a measurement point on the surface of the printed board having a solder portion where the solder is printed on the pad surface and a resist portion where the resist is applied. First sensing means (OS1, D1, D2) that irradiates near-infrared light within 0.9 μm and receives scattered light from the measurement point, and a predetermined angle with respect to the perpendicular to the same measurement point as the measurement point Providing a displacement sensor (2) including second sensing means (OS2, D3) that receives specularly reflected light that is irradiated with the near infrared light at an oblique angle and specularly reflected at the measurement point; A scanning step of relatively scanning a printed circuit board including the solder spot and the resist spot to obtain an output of the first sensing means and an output of the second sensing means; Sensing A displacement calculation step for obtaining a displacement at each scanned measurement point based on the output of the step, and identifying whether the measurement point is a solder location or a resist location based on the output of the second sensing means In response to the measurement point determination step, the identification result and the displacement obtained in the displacement calculation step, the displacement of the pad surface at the bottom of the resist location when the resist location is the measurement point, and the solder location And a measurement calculation step for obtaining the height of the solder spot from the pad surface from the displacement.

  Because it is configured to irradiate near infrared light perpendicular to the resist surface, the displacement of the pad surface at the bottom of the resist can be measured directly and the height (displacement) of the solder spot from the pad surface can be measured. it can.

  An embodiment of a printed solder inspection apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a functional configuration of a displacement sensor and a displacement measuring unit (displacement detecting device) in the embodiment, and is a diagram showing a form in which a displacement sensor and an object to be measured are relatively scanned and inspected. . FIG. 2 is a diagram illustrating a functional configuration of the inspection unit in the embodiment. FIG. 4 is a diagram showing a modification of the embodiment of the displacement sensor of FIG. 1, in which an optical scanning is performed by a light source in the displacement sensor.

  A functional configuration of a displacement measuring unit 100 that performs displacement measurement using the displacement sensor 2 will be described with reference to FIG.

  In FIG. 1, the displacement sensor 2 includes a first near-infrared light source OS1a and a first light receiving element on a single plate-like substrate or a base on a flat plate (hereinafter referred to as “base”, not shown). The positional relationship between the means D1, the second light receiving means D2, the second near-infrared light source OS2a, and the third light receiving means D3 is fixed so that one housing is integrally formed. Is formed. The first near-infrared light source OS1a generates any light (beam) having a wavelength in the range of 0.76 to 0.9 μm, and the first light from the vertical direction is set as the measurement point (target position) on the surface of the substrate 1. It is in a position to irradiate light (hereinafter referred to as “light” although it is a light beam) along the axis. The wavelength of the first near-infrared light source OS1a is set to 0.76 to 0.9 μm because the wavelength is transmitted through the resist 1a when the resist 1a is vertically incident (approximately 0.76 μm or more). This is because it is easily available or inexpensive (approximately 0.9 μm or less).

  The first light receiving means D1 is disposed on a first scattered light path formed at a measurement point at a first angle θ1 with respect to the first optical axis. The second light receiving means D2 is disposed on the second scattered light path formed at the second angle θ2 on the opposite side to the first scattered light path with respect to the first optical axis, and receives the scattered light. (The above is the “first sensing means”). The second near-infrared light source OS2a generates any light (beam) having a wavelength in the range of 0.76 to 0.9 μm, and forms a second light having an oblique angle θ3 with respect to the first optical axis. The measurement point is irradiated with the light of the axis. The third light receiving means D3 is disposed on a specular reflection optical path formed at a third angle 2θ3 with respect to the second optical axis of the second light source at the measurement point, and receives the specular reflection light. (The above is the “second sensing means”.)

  Each of the first light receiving means D1 and the second light receiving means D2 has a light receiving surface with a predetermined length, and corresponds to the light receiving position in the predetermined length direction when scattered light from the measurement point is received. A position detector (PSD: Position Sensitive Detector) that detects optical displacement information is used. In the PSD, light detection elements are arranged in the length direction, and output A and output B, which are electric quantities corresponding to the position, are output from each end as information indicating positions from both ends in the length direction. Then, the displacement information is indicated by (A−B) / (A + B). The PSD is an element that changes the light receiving position according to the displacement of the measurement point and outputs an electric quantity corresponding to the light receiving position, that is, an element that outputs the displacement expressed in the electric quantity. Instead of the PSD, the light receiving position may be directly output as information indicating the displacement by a photodiode array, a CCD, or the like.

  When the measurement point is the solder 1b, each of the first light receiving unit D1 and the second light receiving unit D2 receives the reflected light from the surface thereof to detect the displacement, and the measurement point is a resist 1a having transparency. In this case, the displacement of the bottom portion, that is, the displacement of the surface of the substrate 1 itself without the pad 1c or the pad 1c at the bottom portion is detected. Each of the first light receiving means D1 and the second light receiving means D2 also outputs light amount information (luminance data) at the measurement point. This is used to determine whether or not the pad 1c is present below the resist 1a (if it does not, the surface of the substrate 1 itself is present). However, the pad 1c is made as a copper foil pattern as described above (see FIG. 4), and is thinner than the solder 1b and the resist 1a. Therefore, in the case where it can be considered that the height of the solder 1b from the pad 1c (sometimes referred to as “pad surface”) and the solder height from the substrate 1 can be regarded as substantially the same or can be regarded as the case. The light quantity information from the first light receiving means D1 and the second light receiving means D2 and the determination of the presence or absence of the pad 1c based on the information are unnecessary.

  Further, the third light receiving means D3 reflects the near-infrared light irradiated obliquely on its surface (not transmitting) regardless of whether the measurement point is the solder 1b or the resist 1a. The light amount is measured and light amount information (luminance data) is output. This light quantity information is used to determine whether the measurement point is the resist 1a or the solder 1b.

  In FIG. 1, the scanning mechanism 4 has a driving source such as a motor and a driving mechanism such as a belt, and scans the substrate 1 or the displacement sensor 2 or both of them by relatively moving them. In FIG. 1, the displacement sensor 2 measures displacement while performing main scanning in a direction perpendicular to the arrangement direction in which the respective elements such as the first light receiving means D1 are arranged (depth direction perpendicular to the paper surface of FIG. 1). When the main scanning is completed, the displacement is measured by moving (sub-scanning) in the arrangement direction (direction parallel to the paper surface of FIG. 1), changing the position, and performing the main scanning. By repeating this operation, the displacement of the substrate 1 in the desired range is measured. Note that the scanning direction is an example, and other directions may be used.

  In response to an instruction from a panel or the like (not shown), for example, the control unit 6 receives an instruction of a desired measurement range of the substrate 1 on which the solder is printed, and sends a scanning instruction for the desired range to the scanning mechanism 4 as described above. To scan. In scanning, when the first near-infrared light source OS1a and the second near-infrared light source OS2a use light sources having the same wavelength, if there is no problem of mutual interference between specularly reflected light and scattered reflected light, these Simultaneous irradiation with a light source may be used. When this mutual interference becomes a problem, the first near-infrared light source OS1a and the second near-infrared light source OS2a are alternately switched at the same scanning position (measurement point) on the substrate 1. When light sources having different wavelengths are used, they can be distinguished and detected by the wavelength selection filter, so that they do not necessarily need to be switched and may be configured to output simultaneously.

  The data processing unit 3 and the measurement calculation unit 7 calculate the displacement (data) at the measurement point based on the output from each light receiving means. Then, the measurement point determination unit 5 identifies the resist 1a and the solder 1b, and calculates the solder height from the bottom (pad 1c) of the resist 1a.

Specifically, the adder 3a, the adder 3b, the calculation unit 3c, the memory 3d, the measurement point determination unit 5, and the measurement calculation unit 7 perform the following operations (1) to (4).
(1) The displacement sensor 2 relatively scans the substrate 1 regardless of the solder 1b and the resist 1a under the control of the scanning mechanism 4. The first light receiving means D1 and the second light receiving means D2 receive the light. The adder 3a receives the output A1 of the first light receiving means D1 and A2 output from the second light receiving means D2, and calculates and outputs Ax = A1 + A2. The adder 3b receives the output B1 of the first light receiving means D1 and B2 output from the second light receiving means D2, and calculates and outputs Bx = B1 + B2.

(2) The computing unit 3c calculates a displacement output Lx = (Ax−Bx) / (Ax + Bx) from Ax = A1 + A2 and Bx = B1 + B2, and scans the displacement sensor 2 according to an instruction from the control unit 6. Corresponding to the scanning position (measurement point) of the scanning mechanism 4, it is stored in the memory 3d. At this time, the displacement output when the measurement point is the resist 1a indicates the displacement at the bottom of the resist 1a. If there is a pad 1c at the bottom, it is a displacement of the pad 1c, and if it is the substrate 1 itself, it is a displacement of its surface. That is, as described above, when the wavelength of the first near-infrared light source OS1a is 0.76 to 0.9 μm and the resist 1a is vertically incident, the resist 1a is transmitted and the pad 1c or the substrate 1 is transmitted. This is because the displacement is measured in response to the reflected light reflected by. However, at this time, it is not distinguished whether the measurement point is the displacement output of the solder 1b or the displacement output of the bottom of the resist 1a. Thus, the displacement calculated by the calculation unit 3c and stored in the memory 3d is, to say, measured when measured based on the height of a known specific point of the substrate 1 or calibrated at that height (for example, specific The displacement (height) of the displacement output Lx from the displacement sensor 2 at the point is calibrated to 0). Specific points include, for example, a bare copper foil pattern (pad). Hereinafter, a displacement that does not indicate a reference and a displacement that does not indicate a comparison target indicate a displacement (height) based on the specific point.

  When determining the presence or absence of the pad 1c at the bottom of the resist 1a, the light quantity information of the scattered reflected light from the first light receiving means D1 and / or the second light receiving means D2 is also stored for each measurement point.

(3) On the other hand, the measurement point determination unit 5 receives the output (luminance data) of the third light receiving means D3 and confirms that the amount of reflected light (brightness) is different between the solder 1b and the resist 1a. Utilizing this, it is identified whether the scanning position (measurement position) of the displacement sensor 2 is the solder 1b or the resist 1a. That is, the measurement point determination unit 5 stores in advance a luminance threshold (or threshold range) for specifying the solder 1b and a luminance threshold (or threshold range) for specifying the resist 1a. The outputs of the three light receiving means D3 and their threshold values are compared to identify the solder 1b and the resist 1a. In response to the identification result, the measurement point, the displacement output Lx at the measurement point, and the identification result of the measurement point are stored in the memory 3d. Therefore, in other words, the displacement output Lx is stored separately from the displacement output of the solder 1b as Lh and the displacement output of the bottom of the resist 1a as Lr.

(4) From the memory 3d, the measurement calculation unit 7 uses the displacement output Lh when the measurement point is the solder 1b and the displacement output Lr at the bottom when the measurement point is the resist 1a in the vicinity of the solder 1b. Then, the solder height L = Lh−Lr is obtained based on the displacement output Lr for the bottom of the resist 1a.

  However, as described above, when the height of the solder 1b is obtained from the displacement output Lrp of the pad 1c at the bottom of the resist 1a, the measurement calculation unit 7 stores the first corresponding to the measurement point in the memory 3d. The light quantity information from the first light receiving means D1 and / or the second light receiving means D2 is received, and the light quantity information where the measurement point is the resist 1a is received to determine whether the pad 1c is at the bottom of the resist 1a. Pad determining means for That is, when the pad 1c is present, the amount of light is large, and when there is no pad 1c, the amount of light is small. Therefore, a threshold value for identifying them is stored in advance, and the first measurement point where the measurement point is the resist 1a. The determination is made by comparing with the light amount information from the light receiving means D1 and / or the second light receiving means D2. If the displacement output when the pad 1c is present is Lrp by the determination, the measurement calculation unit 7 obtains the solder height L = Lh−Lrp with the displacement output Lrp of the pad 1c as a reference. In other words, the solder height L indicates the height of the solder with respect to the pad (surface) 1c.

  Here, the measurement calculation unit 7 has been described as having a pad determination unit that receives light amount information at a measurement point of the resist 1a and determines whether or not the pad 1c is in the lower part of the resist 1a. The point determination unit 5 may have pad determination means.

  That is, the measurement point determination unit 5 stores the threshold value (or threshold value range) for identifying the solder 1b, the resist 1a, the pad 1c at the bottom of the resist 1b, and the surface of the substrate 1 at the bottom of the resist 1a. The light receiving means D1 and / or the second light receiving means D2 receives the light quantity information of the scattered reflected light and the light quantity information of the specularly reflected light from the third light receiving means, and identifies each of them by referring to each threshold value. Then, the identification result may be stored in association with the measurement point together with the displacement output Lx output from the calculation unit 3c, that is, the displacement output Lx is the displacement output Lh of the solder 1b or the bottom of the resist. The displacement output Lrp of the first pad 1c or the displacement itself of the surface of the substrate 1 at the bottom of the resist is identified and stored, and the measurement calculation unit 7 detects the displacement output Lh of the solder 1b and the pad 1c at the bottom of the resist. Reads a displacement output Lrp, calculates the height L = Lh-Lrp solder 1b for pad 1c.

  The displacement output Lr is preferably obtained as an average value of the displacement output Lr when the resist 1a in the vicinity of the solder 1b whose height is to be obtained is taken as a measurement point (no distinction of the presence or absence of the pad 1c). Similarly, in the case of the displacement output Lrp, the average value or Lrp is obtained as an average value of the displacement output Lrp where the resist 1a in the vicinity of the solder 1b whose height is to be obtained is measured and the pad 1c is present. It is preferable.

A series of operations in the embodiment will be described.
Step S01: With respect to the measurement point on the surface of the substrate 1 having the solder 1b with the solder printed on the surface of the pad 1c and the resist 1a with the resist applied, the wavelength has any of 0.76 to 0.9 μm. The first near-infrared light source OS1a vertically irradiates light (near-infrared light), and the scattered reflected light is received by the first light receiving means D1 and D2, while the second near-infrared light source OS2a receives the light. A displacement sensor 2 is prepared which irradiates (near infrared light) obliquely and receives the specularly reflected light by the third light receiving means D3.

  Step S02: The scanning mechanism 4 scans the measurement point by relatively moving either the substrate 1 or the displacement sensor 2 according to an instruction from the control unit 6. The outputs of the first light receiving means D1, the second light receiving means D2, and the third light receiving means D3 are acquired.

  Step S03: The adder 3a and the adder 3b receive one output A1 and the other output B1 from the first light receiving means D1, and receive one output A2a and the other output B2 from the second light receiving means D2. In response, Ax = A1 + A2 and Bx = B1 + B2 are calculated. At this time, the adder 3a and the adder 3b receive and calculate the output from each light receiving means for each measurement point to be scanned, and do not distinguish between the solder 1b and the resist 1a. .

  Step S04: The computing unit 3c receives the outputs Ax = A1 + A2 and Bx = B1 + B2, calculates Lx = (A3−B3) / (A3 + B3), and stores it in the memory 3d corresponding to the measurement point.

  Step S05: The measurement point determination unit 5 receives the output of the third light receiving means D3 and compares it with the threshold value stored in advance, whether the scanning position (measurement position) of the displacement sensor 2 is the solder 1b, Whether the resist is 1a is identified, and the identification result is stored in the memory 3d in association with the measurement point together with the displacement output Lx obtained by the calculation unit 3c.

  Step S06: The measurement calculation unit 7 obtains the displacement output Lh when the measurement point is the solder 1b from the memory 3d and the displacement output Lr at the bottom when the measurement point is the resist 1a in the vicinity of the solder 1b. Reading is performed to obtain a solder height L = Lh−Lr based on the displacement output Lr at the bottom of the resist 1a. This is performed for each solder 1b.

  As described above, in the present invention, the optical system of the scattering reflection displacement measurement system using near infrared light and the optical system of the regular reflection displacement measurement system are provided, and the height of the solder 1b from the bottom of the resist 1a is set. Can be sought.

  However, when obtaining the height of the solder 1b from the pad 1c at the bottom of the resist, in step S05 described above, the measurement point determination unit 5 determines the light quantity information from the first light receiving means D1 and the second light receiving means D2. And whether the scanning position (measurement position) of the displacement sensor 2 is the solder 1b or the resist 1a in comparison with the threshold value stored in advance by receiving the output (light quantity information) of the third light receiving means D3. And the pad 1c at the bottom of the resist 1a is identified, and the identification result corresponds to the measurement point together with the displacement output Lx (Lh, Lrp is stored so as to be readable) obtained by the arithmetic unit 3c. And memorize it in the memory 3d (store Lh and Lrp so that they can be read), and in step 06, the measurement calculation unit 7 determines the displacement output Lh when the measurement point is the solder 1b and the vicinity of the solder 1b. Measurement point is read out and displacement output Lrp pad 1c, obtaining the solder height L = Lh-Lrp relative to the displacement output Lrp pad 1c.

  Next, the functional configuration of the inspection unit 200 will be described with reference to FIG. In FIG. 2, the image processing unit 8 receives the layout information (arrangement drawing) of the substrate 1 from the control unit 6 and the position information when scanning and measuring, and the height in the position information from the measurement calculation unit 7. (Displacement output) In response to L, a three-dimensional image representing the quantitative shape of the solder 1b is formed on the layout in accordance with the displacement, and is reproduced and output as an image.

  For example, the image processing unit 8 measures the area (measurement point collection region: for example, the substrate 1) measured from the displacement output L of the measurement calculation unit 7 and the measurement points (coordinates of the measurement points) of the substrate 1 from the control unit 6. Image data representing the area (for example, solder printed area) and volume (for example, the amount of solder) in the cream solder 1b surface printed thereon is generated. The comparison unit 9 receives a design value or the like in the area from the control unit 6 as a reference (area or volume), and calculates and outputs a difference between the image data and the reference. The difference between the displacement (height: for example, the height of the solder 1b) measured at the measurement point and the reference (in this case, for example, the design height at the measurement point) without conversion into image data. May be output. In the above description, the example of the solder area and volume has been described. However, it is also possible to determine misalignment of the solder.

  The determination unit 10 receives the allowable value corresponding to the reference from the control unit 6 and compares it with the output from the comparison unit 9. If the output of the comparison unit 9 is within the allowable value, the determination unit 10 passes, and if the output is outside the allowable value. If it is defective, it is determined as bad.

  The display unit 11 displays the determination result of the determination unit 10. In addition, layout information (for example, a layout diagram of solder locations on the printed circuit board) is received from the control unit 6 and displayed so that it is possible to identify at which position in the layout the solder 1b is defective (or not) and passed. May be. Further, separately or in combination, an image based on the image data generated by the image processing unit 8 can be displayed so that it is possible to identify which part is in a defective soldering state and is acceptable.

[Modification of displacement measurement unit]
In the above, after calculating the displacement of the measurement point, based on the determination result of the measurement point determination unit 5, the solder 1b and the resist 1a are distributed to obtain the height of the solder 1b from the bottom of the resist 1a. . However, based on the determination result of the measurement point determination unit 5, either the output of the displacement sensor 2 or the outputs of the adders 3a and 3b can be assigned to the data of the solder 1b and the resist 1a. Therefore, a configuration may be used in which the adders 3a and 3b and the calculation unit 3c perform the calculation and calculate the height of the solder 1b from the bottom of the resist 1a based on the result.

  Therefore, in other words, the displacement measuring unit 100 determines whether the measurement point is the solder 1b or the resist 1a based on the light amount information (luminance data) based on the output of the third light receiving means D3. In response to the identification result, the displacement of the bottom of the resist 1a is calculated based on the output of the first sensing means when the scattered light from the bottom of the measurement point is received using the resist 1a as the measurement point, and the solder 1b The height (displacement) of the solder 1b with reference to the displacement of the bottom of the resist 1a based on the output of the first sensing means when the scattered light from the solder 1b is received with the measurement point as the measurement point It can be said that.

[Other Embodiments of Displacement Sensor]
A displacement sensor 2a as another embodiment of the displacement sensor 2 is shown in FIG. FIG. 3A is a view of the displacement sensor 2a as viewed from above, and FIG. 3B is a view as viewed from the side, both of which show optical paths between the elements. FIG.3 (c) is a figure which shows the optical path seen from the arrow A or arrow B of FIG.3 (b). 3, elements having the same reference numerals as those in FIG. 1 have the same functions.

  The main difference in configuration of the displacement sensor 2a from the embodiment of FIG. 1 is that in the embodiment of FIG. 1, the entire displacement sensor 2 is mechanically moved to perform main scanning. In the displacement sensor 2a, the main scanning is performed using the rotation of the polygon mirror PM. Sub-scanning is performed by mechanically moving either or both of the displacement sensor 2a and the substrate 1 as in the above embodiment. The scanning directions of main scanning and sub-scanning are the same as in the first embodiment (may be different). Therefore, the scanning mechanism 4 of FIG. 1 is in charge of only sub-scanning in this other embodiment. Similarly, for the main scanning, the control unit 6 in FIG. 1 directly controls the polygon mirror PM of the displacement sensor 2a to perform the main scanning. Other configurations are the same as those in FIG. 1 except as described below.

  Since the position information of the scanning position (measurement point) in this case generates a timing signal corresponding to the rotation angle when the polygon mirror PM is rotated in a drive unit (not shown) that rotates the polygon mirror PM, It is determined by the timing signal and a sub-scanning instruction from the control unit 6. Therefore, the measurement point information stored in the memory 3d is stored based on the timing signal and the sub-scanning instruction.

  The optical configuration of the displacement sensor 2a will be described with reference to FIG. The first light receiving means D1, the second light receiving means D2, and the third light receiving means D3 have the same configuration and the same functions and operations as those described in the embodiment of FIG. 1, but with respect to the main scanning direction. Thus, sensing is performed with a width corresponding to the main scanning distance (in FIG. 3A, the vertical direction of the paper surface, and in FIG. 3B, the depth direction of the paper surface). The combination of the light receiving lens K1a and the imaging lens K1b, the combination of the light receiving lens K2a and the imaging lens K2b, and the combination of the light receiving lens K3a and the imaging lens K3b constitute the condensing functional elements K1, K2, and K3, respectively. The light (reflected light) collected by the light receiving lenses K1a, K2a, K3a is converted into parallel light, and the imaging lenses K1b, K2b, K3b receiving the parallel light are connected to the light receiving means D1, D2, D3. It has a function to image. Similarly to each of the light receiving means D1, D2, and D3, the width is the distance of the main scanning direction with respect to the main scanning direction (the vertical direction in FIG. 3A and the depth direction in FIG. 3B). It is configured to receive light and form an image.

  3A and 3B, the laser OSC1a, the half mirror OSC1b, the mirror OSC1c, the mirror OSC1d, the polygon mirror PM, the mirror OSC1e, the fθ lens OSC1f, and the entire mirror OSC1g are equivalently equivalent to the first OS in FIG. This corresponds to the near-infrared light source OS1a. However, it differs in that the main scanning is performed by the polygon mirror PM. Further, the entire laser OSC1a, half mirror OSC1b, mirror OSC2a, mirror OSC1c, polygon mirror PM, mirror OSC2b, and fθ lens OSC2c equivalently correspond to the second near-infrared light source OS2a in FIG. FIG.3 (c) is a figure seen from the arrow A and B of FIG.3 (b), and is a figure which shows a mode that an optical path direction is converted.

  Next, the optical path and main scanning will be mainly described. The light output from the laser OSC1a is partially branched by the half mirror OSC1b, reflected by the mirror OSC1c and the mirror OSC1d, and input to the polygon mirror PM. The light input to the polygon mirror PM is emitted to the mirror OSC1e at an angle corresponding to the rotation by the rotation of the polygon mirror PM (right rotation in FIG. 3A). The mirror OSC1e turns back along the optical path specularly reflected with respect to the angle when the received light is received, and sends it to the fθ lens OSC1f. As shown in FIG. 3 (c), the fθ lens OSC1f is an optical path in which light incident at an angle according to the rotation of the polygon mirror PM is arranged in parallel in the scanning direction at a constant interval with an optical path having an angle spreading according to the rotation. And sent to the mirror OSC1g through the optical path. The mirror OSC1g irradiates the measurement point with the received light from the vertical direction. At this time, in FIG. 3B, the measurement point is main-scanned in the depth direction from the front of the sheet according to the rotation of the polygon mirror PM. The first light receiving means D1 and the second light receiving means D2 receive the scattered light from the measurement point for the irradiation from the mirror OSC1g and measure the displacement.

  On the other hand, of the light output from the laser OSC1a, the remaining light branched by the half mirror OSC1b is reflected by the mirror OSC2a and input to the polygon mirror PM. The light input to the polygon mirror PM is emitted to the fθ lens OSC2c at an angle corresponding to the rotation by the rotation of the polygon mirror PM. Similar to the fθ lens OSC1f, the fθ lens OSC2c passes light incident at an angle according to the rotation of the polygon mirror PM through an optical path arranged in parallel in the scanning direction at a constant interval as shown in FIG. Further, the measurement point is irradiated from obliquely above at a certain angle θ3 with respect to the vertical. At this time, in FIG. 3B, the measurement point is main-scanned from the depth of the paper to the front in accordance with the rotation of the polygon mirror PM (in the opposite direction to the scanning by the vertical light from the mirror OSC1g). ). The third light receiving means D3 receives the specularly reflected light from the measurement point for the irradiation from the fθ lens OSC2c and measures the displacement.

  As described above, the output light from the mirror OSC1g plays the role of the light source of the scattering reflection measurement system (first sensing means), and the output light from the fθ lens OSC2c is the regular reflection measurement system (second It plays the role of the light source of the sensing means. However, although both light beams are irradiated at the same measurement point, the scanning directions are reversed because the same polygon mirror PM is used. In other words, the scattering reflection measurement system and the regular reflection measurement system have different scanning times and directions at the same measurement point in the same main scanning. This only differs in the order of measurement, and there is no change in that the same measurement point is measured on both sides. Also, the time difference when scanning is short and has little effect. Further, the irradiation position error due to the different scanning directions can be suppressed within an allowable range.

  As described above, when the scattering reflection measurement system and the specular reflection measurement system are performed simultaneously, interference (crosstalk) occurs due to the use of the laser OSC1a having the same wavelength, and an error may occur. In this case, for example, in FIG. 3A, if the angle at which one side of the octagon of the polygon mirror PM faces the axis center is γ, the regular reflection measurement system during the rotation of the polygon mirror PM between 0 and γ / 2. , And by measuring with a positive scattering reflection system with the remaining rotation of the polygon mirror PM by the remaining γ / 2 to γ, alternating measurement can be performed for each side, and crosstalk can be prevented. . For this purpose, adjustment can be performed by taking into consideration the incident angle and position on the polygon mirror PM (not shown).

  The printed solder inspection method using the displacement sensor 2a can be performed in the same manner as in the embodiment of FIG.

It is a figure which shows the function structure of a displacement sensor and a measurement part among embodiment, Comprising: It is a figure of the form which scans and inspects between a displacement sensor and a to-be-measured object relatively. It is a figure which shows the function structure of a test | inspection part among 1st Embodiment. It is a figure which is a modification of 1st Embodiment, Comprising: The type of embodiment which performs an optical scan with a light source within a displacement sensor. It is a figure which shows the relationship between the resist in a printed circuit board, solder, and a pad. It is a figure for demonstrating permeation | transmission and reflection of visible light and near-infrared light in a resist.

Explanation of symbols

1 substrate (printed board), 2 displacement sensor, 3 data processing unit,
3a, 3b adder, 3c arithmetic unit, 3d memory,
4 scanning mechanism, 6 control unit, 7 measurement operation unit, 8 image processing unit, 9 comparison unit, 10 determination unit, 11 display unit, 100 displacement measurement unit, 200 inspection unit,
D1 first light receiving means, D2 second light receiving means, D3 third light receiving means,
K1a, K2a, K3a Light receiving lens K1b, K2b, K3b Imaging lens OSC1a Laser (near infrared light), OSC1b half mirror,
OSC1c, OSC1d, OSC1e, OSC1g Mirror OSC2a, OSC2b Mirror OSC1f, OSC2c fθ Lens PM Polygon Mirror

Claims (4)

Near-infrared light within a wavelength range of 0.76 to 0.9 μm that passes through the resist perpendicularly to the measurement point on the surface of the printed board having the solder spot with the solder printed on the pad surface and the resist spot coated with the resist The first sensing means (OS1, D1, D2) receiving the scattered light from the measurement point, and the near-infrared light at a predetermined oblique angle with respect to the perpendicular to the same measurement point as the measurement point A displacement sensor (2) including second sensing means (OS2, D3) that receives the specularly reflected light that is reflected at the measurement point and is specularly reflected at the measurement point;
A data processing unit (3) for obtaining a displacement at each measurement point on the surface of the printed board based on an output of the first sensing means;
A measurement point determination unit (5) for identifying whether at least the measurement point is a solder location or a resist location by luminance data based on the output of the second sensing means;
In response to the identification result and the displacement obtained by the data processing unit, a measurement calculation unit (7) that obtains the height of the solder location relative to the pad surface at the bottom of the resist location when the resist location is taken as a measurement point. And a printed solder inspection apparatus. The first sensing means outputs luminance data of a measurement point;
The measurement point determination unit compares the measurement point with the solder location by comparing with the threshold value stored in advance based on the luminance data of the first sensing means and the luminance data of the second sensing means. Identifying the pad surface at the bottom of the resist;
The printed solder inspection according to claim 1, wherein the measurement calculation unit obtains the height of the solder spot from the pad surface based on the identification result and the displacement obtained by the data processing unit. apparatus. Near-infrared light within a wavelength range of 0.76 to 0.9 μm through which the resist passes perpendicularly to a measurement point on the surface of the printed board having a solder spot with a solder printed on the pad surface and a resist spot coated with a resist The first sensing means (OS1, D1, D2) receiving the scattered light from the measurement point, and the near-infrared light at a predetermined oblique angle with respect to the perpendicular to the same measurement point as the measurement point A displacement sensor (2) including second sensing means (OS2, D3) that receives the specularly reflected light that is reflected at the measurement point and is specularly reflected at the measurement point;
A measurement point determination unit (5) for identifying at least the measurement point as a solder location or a resist location based on luminance data based on the output of the second sensing means; The displacement of the pad surface is calculated based on the output of the first sensing means when the scattered light from the pad surface at the bottom of the measurement point is received with the resist location as the measurement point, and the solder location A displacement measuring unit (100) for determining the height of the solder spot from the pad surface based on the output of the first sensing means when the scattered light from the solder spot is received as a measurement point Printed solder inspection apparatus characterized by that. Near-infrared light within a wavelength range of 0.76 to 0.9 μm through which the resist passes perpendicularly to a measurement point on the surface of the printed board having a solder spot with a solder printed on the pad surface and a resist spot coated with a resist The first sensing means (OS1, D1, D2) receiving the scattered light from the measurement point, and the near-infrared light at a predetermined oblique angle with respect to the perpendicular to the same measurement point as the measurement point Preparing a displacement sensor (2) including second sensing means (OS2, D3) that receives specularly reflected light that is regularly reflected at the measurement point.
Scanning the displacement sensor relative to the printed circuit board including the solder spot and the resist spot to obtain the output of the first sensing means and the output of the second sensing means;
A displacement calculation step for obtaining a displacement at each scanned measurement point based on an output of the first sensing means;
A measurement point determination step for identifying whether the measurement point is a solder location or a resist location based on the output of the second sensing means;
Based on the identification result and the displacement obtained in the displacement calculation step, the pad surface displacement at the bottom of the resist location when the resist location is used as a measurement point, and the displacement of the solder location, A printed solder inspection method comprising: a measurement calculation step for obtaining a height of the solder spot from the surface.

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