JP3509040B2 - Probe movement control method in circuit board inspection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board inspection apparatus, and more particularly, to the quality of a connection between a circuit pattern and a lead of a mounted component on a board to be inspected. When inspecting, the position deviation occurring between the reference position coordinate data stored in advance and the corresponding measured position coordinate data is detected as a conversion parameter, and the probe movement position is corrected based on the conversion parameter. The present invention relates to a method for controlling the movement of a probe in a circuit board inspection apparatus that can accurately contact a measurement point. 2. Description of the Related Art A circuit board inspection device such as an in-circuit tester (hereinafter, referred to as a "substrate inspection device") moves at least two probes to a measurement point in a controllable manner to make electrical contact. By doing so, a break or short circuit of a circuit pattern printed on a substrate to be inspected (in the present specification, a “circuit substrate” that is actually inspected with mounting components such as ICs) is used. In addition, various necessary inspections such as the performance of mounted components such as ICs and the quality of the mounted state can be performed. By the way, in the above-mentioned board inspection apparatus,
Since it is necessary to accurately move at least two probes to a predetermined measurement point, the standard of the substrate to be inspected is determined in order to establish a correspondence relationship with the substrate to be actually inspected. Design data such as CAD data used when designing the model board is stored in the memory in advance as reference position coordinate data (logical position coordinates), and the probe is moved based on the reference position coordinate data. On the other hand, the substrate to be inspected may be displaced when being fixed at a predetermined position of the substrate inspection apparatus, a printed pattern may be displaced, or the substrate itself may be distorted due to expansion and contraction. May not be able to correspond to the reference position coordinate data. In such a case, even if the probe is moved on the basis of the reference position coordinate data, it cannot be naturally brought into accurate contact with a measurement point at a predetermined position on the substrate to be inspected. For this reason, necessary correction processing is performed each time so that a correspondence relationship can be obtained between the previously obtained reference position coordinate data and the actually measured position coordinate data at the corresponding position of the substrate to be inspected, and the corrected position obtained after the correction. It is necessary to move the probe based on the coordinate data. [0006] In this case, the correction method which has been conventionally performed is to use reference position coordinate data pre-fetched from a reference position mark (for example, a fiducial mark) on a standard model substrate and the reference position coordinate data on the inspection target substrate. Determine the substrate position conversion parameters using the measured values obtained by measuring the position corresponding to the mark using a pattern matching method by the normalized correlation coefficient by the position correction camera,
The movement position is corrected by performing a substrate position correction process based on the substrate position conversion parameter, so that the probe is brought into accurate contact with the measurement point. That is, in the above-mentioned conventional method, the reference position coordinate data (x,
y) and the relationship between measured position coordinate data indicating the actual position of the substrate to be inspected. The calculation is performed by calculating the actual position (X, Y) of the measurement point using the following equation. Note that among the elements a ₁ , b ₁ , c ₁ , d ₁ , Ox ₁ , and Oy ₁ of the matrix in Equation 1 above,
a ₁ and b ₁ are the correction amounts in the X-axis direction, c ₁ and d ₁ are the correction amounts in the Y-axis direction, Ox ₁ is the translation amount in the X-axis direction,
Oy ₁ indicates the amount of parallel movement in the Y-axis direction. In addition,
Each numerical value shown in the third row in the above equation 1 is based on an expansion coefficient matrix (homogeneous displacement matrix). Thus, each probe can be accurately moved to the measurement point on the substrate to be inspected based on the corrected position coordinate data obtained by solving the simultaneous equations derived from the above equation (1). By the way, according to the above-described conventional method, the probe can be accurately moved with respect to the substrate to be inspected in which the positional deviation (including the positional deviation of the circuit pattern) has occurred. To make necessary inspections. However, the above-mentioned conventional method is based on the substrate itself, so that the position of the mounted component such as an IC is displaced on the substrate to be inspected. Even if you try to test whether the leads of the mounted components to be connected to the board are correctly soldered and connected to each other, it is necessary to move the probe accurately for each measurement point of these circuit patterns and leads. There was an inconvenience that could not be done. The present invention has been made in view of the above-mentioned problems in the prior art, and even when a mounted component itself is displaced on a board to be inspected, a probe is accurately brought into contact with a measurement point to obtain a circuit pattern. It is an object of the present invention to provide a method for controlling the movement of a probe in a circuit board inspection apparatus capable of inspecting the quality of a connection state between the probe and a lead of the mounted component. SUMMARY OF THE INVENTION The present invention has been made in order to achieve the above-mentioned object, and has the following structural features: a holding portion for holding a substrate to be inspected; At least two movable parts that individually move in the X-Y axis directions along parallel planes, probes that are separately attached to these movable parts, and that move up and down in the Z-axis direction, and at least one of the movable parts In a circuit board inspection apparatus having at least an apparatus for position correction mounted on the device body and performing an image pickup required for an image recognition technique, a lead of a mounted component arranged at a predetermined position on a board to be inspected is connected to the lead. One of the probes, which are controlled to move freely to the respective measurement points in order to inspect the connection state with the circuit pattern to be performed, which contacts the circuit pattern side. The lobe is a reference position coordinate data previously captured from the reference position of the standard model substrate, and the measured position coordinate data obtained from the position corresponding to the reference position on the inspected substrate via the position correction camera. A board position conversion parameter as a correction amount is obtained by comparison, the movement position is corrected by a board position correction process based on the board position conversion parameter, the measurement position is contacted, and the measurement point is contacted. The probe is obtained via the position correction camera from the reference component position coordinate data previously captured from the reference mounting component of the standard model board and the mounting component corresponding to the reference mounting component on the board to be inspected. A part position conversion parameter as a correction amount is obtained by comparing the measured part position coordinate data with the measured part position coordinate data. In contacting the measuring point by performing the moving position corrected by the position correction processing of the mounting part based on said substrate position transformation parameter. [0013] For this reason, not only when the substrate to be inspected held by the holding unit is displaced but also when the position of the mounted components arranged on the substrate to be inspected is displaced. However, since the positional deviation can be converted into correction data by a predetermined position correction process in correspondence with each of them, one probe is attached to the measurement point on the circuit pattern side, and the measurement on the lead side of the mounted component is performed. The point can be brought into contact with the other probe after being accurately moved. Therefore, whether or not the circuit pattern of the board to be inspected and the leads of the mounted components to be connected thereto are correctly connected is determined by always bringing the corresponding probes into contact with the respective measurement points to perform the correct inspection. can do. FIG. 1 is a plan view showing a schematic configuration example of a substrate inspection apparatus to which the present invention is applied. The whole includes a holding section 12 for positioning and holding a substrate 31 to be inspected, A guide rail portion 13 fixedly arranged on the apparatus main body 11 in the X-axis direction, and a pair of guide rails 13 guided by the guide rail portion 13 and arranged to freely reciprocate in the X-axis direction in the Y-axis direction; Of the movable arms 14, 15 and
15 is provided with at least the apparatus main body 11 having movable parts 16 and 17 which are separately disposed so as to freely reciprocate in the Y-axis direction. The pair of movable arms 14, 1
The movements of the movable member 5 and the movable portions 16 and 17 are controlled by a servo mechanism (not shown) or the like. The movable parts 16 and 17 are provided with probes 18 and 19 which can be moved up and down (in the Z-axis direction) by driving and controlling them via an air cylinder, a disk crank or a timing belt. Each of the movable parts 16 is provided separately, and at least one of the movable parts 16 is provided.
Is provided with a position correction camera 20 that performs imaging necessary for an image recognition technique when performing position correction processing. Therefore, according to the board inspection apparatus shown in FIG. 1, an arbitrary direction (X
−Y direction), the probes 18 and 19 are
As shown in the figure, the measurement points P ₁ , P ₂
After being moved upward, it is lowered (in the Z-axis direction), and the probes 18 and 19 are brought into contact with the measurement points P ₁ and P ₂ , whereby necessary inspection can be performed. FIG. 2 is a block diagram showing a schematic functional configuration of the substrate inspection apparatus shown in FIG. 1. The apparatus comprises a measuring means 21 connected to the probes 18 and 19, and a servo mechanism (not shown). Through the pair of movable arms 14,
A servo system control unit 22 that controls the movement of the movable unit 15 and each of the movable units 16 and 17, and a memory 23 that stores an inspection step and an inspection program including position coordinate data of the measurement points P ₁ and P ₂ shown in FIG. And control means (CPU) for controlling the measuring means 21 and the servo system control section 22 according to the inspection program stored in the memory 23.
24, a keyboard 25 for giving necessary inputs and instructions,
At least an output display means 26 including a CRT or a printer is provided. The measuring means 21 includes a not-shown measurement signal generating section and a signal measuring section, and the measuring signal generating section and the signal measuring section can be selected by the probe 18 or 19 via a not-shown scanner. It is designed to be connected. As shown in FIG. 1, for example, three reference position marks 32 made of the same copper foil as the circuit pattern 33 are provided on the substrate 31 to be inspected by using the substrate inspecting apparatus having the above configuration. The substrate 31 to be inspected held by the holding unit 12 is displaced as shown in FIG. 3, for example, by imaging the positions of these reference position marks 32 with the position correcting camera 20. Under the state, it is grasped that it is arranged in the holding unit 12, and it is possible to perform a necessary correction and perform an inspection. On the other hand, apart from the problem of whether or not the substrate 31 to be inspected is correctly positioned and held on the holding portion 12,
As shown in FIG. 4 and FIG. 5 which is an enlarged view of a main part thereof, the mounting component 34 itself on the substrate 31 to be inspected is displaced from the original mounting position indicated by the broken line to the position indicated by the solid line and the dashed line. May be done. When the mounted component 34 is displaced in this way, the leads 35 of the mounted component 34 are also displaced with respect to the corresponding circuit pattern 33 and are soldered. In order to check whether or not the lead 35 of the mounted component 34 is correctly connected to the corresponding circuit pattern 33, as shown in FIG. 35b is a measurement point P ₁ of the circuit pattern 33 on the side are soldered,
The other probe 19 needs to be contacted respectively to the measurement point P ₂ of the shoulder portion 35a of the lead 35. However, as shown in FIG. 5, when the mounting component 34 is displaced on the substrate 31 to be inspected,
The position of the lead 35 also shifts by the position shift,
To accurately contact the probe 19 to the measuring point P ₂ of the shoulder portion 35a of the lead 35 in such a state, mounting components 3 position to move the probe 19
In this case, it is necessary to perform a position correction process for correcting the position corresponding to the position shift condition of No. 4. FIG. 7 is a coordinate conversion flow showing a processing procedure for correcting the position of each of the measurement points P ₁ and P ₂ under the conditions shown in FIGS. 3 and 5, and is schematically shown for convenience of explanation. The following description is based on the example shown in FIG. That is, first, the logical position coordinate storage processing S
_{In FIG. 1} , design data such as CAD data used in designing a standard model board of the board 31 to be inspected is used as reference position coordinate data in order to establish a correspondence between the board 31 to be actually inspected. Is stored in the memory 23. Note that after a logical position coordinate storage processing S ₁ is a group offset processing S ₂ to rewrite corresponding data in relation to the reference position coordinates data fetched at that time, measurement points P _1, P of the probe 18, 19 ₂ and the points offset processing S ₃ which correspond to the design data is performed, the processed data is to be stored in the memory 23. After the group offset processing S ₂ and the point offset processing S ₃ performed as described above, if the substrate 31 to be inspected actually held by the holding section 12 is displaced, the reference position coordinate data substrate position correction conversion process S ₄ to correct to correspond to the displacement amount of time that a is performed. [0026] In the substrate position correction conversion process S ₄ steps, firstly, the position of the reference position mark 32 of the substrate to be inspected 31 is captured by the position correction camera 20 shown in FIG. 1, the by known image recognition technique A position check is performed. At this time, if it is confirmed that the position of each reference position mark 32 is misaligned, the position of each of the reference position marks on the standard model board, which is previously taken in as reference position coordinate data, is determined. A conversion parameter is obtained in relation to the position, and based on the obtained conversion parameter, a position correction conversion process corresponding to the positional shift of the substrate 31 to be inspected is performed by using the above formula 1, and the probes 18 and 19 are inspected. The coordinates are stored in the memory 23 as position coordinate data necessary for moving to the measurement points P ₁ and P ₂ corrected in accordance with the displacement of the substrate 31. [0028] In component position correction conversion process S ₅ performed subsequent to the substrate position correction conversion processing S _4, first, the lead has a measurement point P ₂ of the probe 19 35
Is mounted by the position correcting camera 20, and its position is confirmed by a known image recognition method. At this time, when it is confirmed that the mounted components 34 on the board 31 to be inspected are displaced, for example, at a position indicated by a solid line instead of a predetermined position indicated by a dashed line in FIG. The reference component position coordinate data as the logical position coordinates previously taken from the reference mounting component of the standard model board, and the actual position of the mounting component 34 on the inspected board 31 corresponding to the reference mounting component, A component position conversion parameter is obtained using an actual measurement value obtained by measurement by the position correction camera 20 using the pattern matching method based on the normalized correlation coefficient. In other words, the above-described method uses reference position coordinate data (x, y) indicating the position of the reference mounted component on the standard model board, and measured position coordinate data indicating the actual position of the mounted component 34 on the board 31 to be inspected. [Equation 2] Is performed by the following equation. Note that among the elements a ₂ , b ₂ , c ₂ , d ₂ , Ox ₂ , and Oy ₂ of the matrix in Equation 2, a ₂
, B ₂ are the correction amounts in the X-axis direction, c ₂ , d ₂ are the correction amounts in the Y-axis direction, Ox ₂ (X _{0 in} FIG. 8) is the translation amount in the X-axis direction, and Oy ₂ (Y _{0 in} FIG. 8) indicates the amount of parallel movement in the Y-axis direction. Each numerical value located at the lowermost stage in Equation 2 indicates the movement of the probes 18 and 19 in the z-axis direction. In order to simplify Equation 2, the following equation can be substituted. Example 1 a ₂ = d ₂ , b ₂ = −c ₂ a ₂ = cos θ, b ₂ = −sin θ, c ₂ = si
nθ, d ₂ = cos θ Here, θ is a value of the mounted component 34 (the reference mounted component) that is correctly arranged as shown by a dashed line in FIG. Indicates the tilt angle (position shift). Example 3 a ₂ = 1, b ₂ = 0, c ₂ = 0, d ₂ = 1 Thus, the component position correction conversion processing S ₅
After that, the arm offset processing S _{6 for} setting the same coordinate system for the movable arms 14 and 15 is performed.
The after performing, in order to store in the memory 23 as the positional coordinate data obtained measurement points P ₁ of one of the probes 18 into contact with the circuit pattern 33 of the test substrate 31 at the substrate position correction conversion process S ₄ physical movement coordinate storage processing S ₇ is performed. At the same time, the measurement point P ₂ of the other probe 19 to be brought into contact with the lead 35 of the mounting component 34 of the board 31 to be inspected is calculated by the above formulas 1 and 2.
Is multiplied by Physical movement coordinate storage processing S ₇ for causing the stored when the similarly to the memory 23 measurement points P ₁ as the position coordinate data is calculated (physical movement coordinate) is performed by. [0034] After passing through the physical movement coordinate storage processing S ₇ performed in this manner, each probe 18 and 19, the memory 2
Based on the position coordinate data after the correction processing stored in 3, the movement of the probe 1 to the corresponding measurement points P ₁ and P _{2 of the} substrate 31 to be inspected is controlled, and as shown in FIG.
Reference numeral 8 can accurately contact the circuit pattern 33, and the other probe 19 can accurately contact the shoulder 35 a of the lead 35 of the mounting component 34. The processing step shown as the logical current position storage processing S ₈ in FIG. 7 is the reference mounting on the side of the standard model board which has a positional relationship corresponding to the mounting parts 34 of the non-tested board 31 to be actually tested. This is a process of teaching a part and storing it in the memory 23 as position data.
The servo motor, not shown, since it is intended to move coordinates based on the detected position of the position sensor and the detected position is feedback controlled to match the position by passing through the encoder position storage processing S ₉ in FIG. 7 The number of pulses counted by the encoder functioning as a sensor is held as the detection position (current position). Since the present invention is configured in this manner, not only does the position of the board 31 to be inspected held by the holder 12 be displaced, but also the mounting components disposed on the board 31 to be inspected. Even in the case where the position shift has occurred in 34 itself, the position shift can be converted into correction data by a predetermined position correction process corresponding to each case. Accordingly, one probe 18 is positioned above the measurement point P ₁ of the circuit pattern 33 to which the leg 35 b of the lead 35 of the mounted component 34 is soldered.
Other probe 19, after moving the control on each of the measurement points P ₂ of the shoulder portion 35a of the lead 35 of the mounting component 34, by lowering the probe 18, 19,
The corresponding measuring points P ₁ , P ₂ can be brought into accurate contact. For this reason, the circuit pattern 33 of the substrate 31 to be inspected and the lead 3 of the mounting component 34 to be connected thereto are
Whether or not 5 is correctly connected means that the corresponding probe can be brought into contact with the measurement points P ₁ and P ₂ of the respective 18 and 19 to always perform the correct inspection. As described above, according to the present invention, not only does the position of the substrate to be inspected held by the holding portion be displaced, but also the mounting components disposed on the substrate to be inspected. Even if there is a displacement in the probe itself, the displacement can be converted into correction data by a predetermined position correction process corresponding to each displacement. Can be brought into contact with the measurement point on the lead side of the mounted component after accurately moving the other probe. Therefore, whether or not the circuit pattern of the substrate to be inspected and the leads of the mounted components to be connected thereto are correctly connected is determined by always bringing the corresponding probes into contact with the respective measurement points to perform the correct inspection. can do.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing a schematic configuration example of a substrate inspection apparatus provided for carrying out the present invention. FIG. 2 is a block diagram showing a schematic functional configuration of the substrate inspection apparatus shown in FIG. 1; FIG. 3 is a plan view showing another arrangement example of the substrate to be inspected in the substrate inspection apparatus shown in FIG. FIG. 4 is a plan view showing an example of arrangement of mounted components on a substrate to be inspected. FIG. 5 is an enlarged plan view showing a portion surrounded by a chain line in FIG. 4; FIG. 6 is an explanatory view exemplifying an arrangement relationship of probes when inspecting a connection state between a lead of a mounted component and a circuit pattern on a substrate to be inspected. FIG. 7 is an explanatory diagram showing a procedure for coordinate conversion processing in the present invention. FIG. 8 is a schematic diagram for clarifying a relationship with the coordinate conversion processing shown in FIG. 7; DESCRIPTION OF SYMBOLS 11 Main body 12 Holder 13 Guide rails 14 and 15 Movable arms 16 and 17 Movable parts 18 and 19 Probe 20 Position correction camera 21 Measurement unit 22 Servo system control unit 23 Memory 24 Control unit (CPU ) 25 keyboard 26 output display means 31 to be inspected substrate 32 reference position mark 33 circuit pattern 34 mounting component 35 lead 35a shoulders 35b legs P _1, P ₂ measurement points

Continuation of the front page (56) References JP-A-2-287164 (JP, A) JP-A-6-258394 (JP, A) JP-A-6-129993 (JP, A) JP-A-4-252976 (JP) JP-A-60-47968 (JP, A) JP-A-4-307950 (JP, A) JP-A-3-84945 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB G01R 31/26-31/3193 H01L 21/66

Claims (1)

(57) Claims 1. A holding portion for holding a substrate to be inspected, and at least two members each separately moving in the XY axis direction along a plane parallel to the held substrate to be inspected. A movable part, a probe attached to each of these movable parts and moved up and down in the Z-axis direction, and a position correction camera attached to at least one of the movable parts and taking an image necessary for an image recognition technique. At least a circuit board inspection apparatus provided in the apparatus main body, wherein each measurement point is used to inspect a connection state between a lead of a mounted component arranged at a predetermined position on a substrate to be inspected and a circuit pattern to which the lead is to be connected. One of the probes, which are controlled to move freely in contact with the circuit pattern side, has a reference position coordinate data previously taken from a reference position on the standard model board. And the measured position coordinate data obtained from the position corresponding to the reference position on the inspected substrate via the position correcting camera to obtain a substrate position conversion parameter as a correction amount. The moving position is corrected by the correction processing of the substrate position based on the conversion parameter to make contact with the measurement point, and the other probe that comes into contact with the lead side of the mounted component is previously captured from the reference mounted component of the standard model substrate. The reference component position coordinate data is compared with the actually measured component position coordinate data obtained from the mounted component corresponding to the reference mounted component on the board to be inspected via the position correcting camera, and component position conversion as a correction amount is performed. Parameters are determined, and the position of the mounted component is corrected based on the component position conversion parameter and the board position conversion parameter. Movement control method of the probe in the circuit board inspection apparatus characterized by contacting the measuring point fixes.