Method and Apparatus of PCBA first article inspection

Abstract

The present invention relates to a method for inspecting whether a PCBA prototype is defective by contacting a pair of probes to the electrodes at both ends of an electronic component of a PCBA prototype, in which the electronic component is attached with double-sided tape rather than fixed by soldering on a substrate to be inspected, and measuring electrical characteristics. The method comprises: a step of setting measurement reference coordinates (X, Y) based on the design reference position of the electronic component; a first measurement step of moving a pair of probes upward from the measurement reference coordinates and then lowering them to measure the electronic component; a first determination step of determining the electronic component as normal if the measurement value in the first measurement step is within a normal range, determining it as defective if it is outside the normal range, and determining that the electronic component has deviated from the reference position if no valid measurement value is detected; a first correction coordinate calculation step of calculating a first correction coordinate in a predetermined direction centered on the measurement reference coordinates according to a pre-set error table if the electronic component is determined to have deviated from the reference position in the first determination step; and a second measurement step of moving the probes to the first correction coordinates to measure the electronic component. It includes a second determination step in which the electronic component is determined to be normal if the measurement value in the initial stage is within the normal range, determined to be defective if it is outside the normal range, and determined to be out of reference position if no valid measurement value is detected.

Description

Technology Field

[0001] The present invention relates to a method and apparatus for inspecting a PCBA prototype, and more specifically, to a method and apparatus for inspecting whether a PCBA prototype has defects in which electronic components are attached with double-sided tape. Background Technology

[0002] Various passive electronic components, such as inductors (L), capacitors (C), and resistors (R), are mounted on an electronic circuit board (Printed Circuit Board Assembly, hereinafter 'PCBA'), and these are typically mounted through a surface mount technology (SMT) process.

[0003] When manufacturing such PCBAs, a first article is constructed by temporarily attaching electronic components to a dummy board, followed by an inspection process to determine the functionality of the components by measuring their electrical characteristics. At this stage, the electronic components are not attached with the same soldering as in actual mass-produced products; instead, measurements are taken while they are temporarily attached using methods such as double-sided tape.

[0004] Conventional automated inspection devices measure electrical characteristics by using a pair of probes to contact the electrodes at both ends of electronic components, thereby determining whether a defect exists. In this process, a pair of probes, positioned at an angle to face left and right, moves in the XY direction and then descends along the inclined axis to contact the electronic component. However, in this structure, there are instances where the probes apply force in a direction deviating from the reference line, causing the temporarily fixed components to be pushed out or misaligned. Consequently, this leads to reduced reliability of measurement values ​​and inspection defects caused by the displacement of electronic components, resulting in a problem where the accuracy and repeatability of the initial product inspection process cannot be ensured.

[0005] To solve these problems, the inventor proposed a PCBA initial product inspection device that incorporates a structure in which a pair of probes come into contact with both ends of an electronic component in mutually opposing directions along a reference line, and this was registered as Patent No. 10-2637633. The above registered patent, which forms the basis of the present invention, is configured so that the force applied by the probes during measurement acts in opposite directions along the same line, thereby preventing displacement or detachment of the temporarily attached electronic component and significantly improving the reliability and repeatability of the initial product inspection results. This technology is currently implemented in commercial equipment and is in actual use.

[0006] Meanwhile, LCR electronic components are typically positioned at right angles of 0° or 90° when mounted on a substrate via the SMT process. This right-angle alignment method has become an established industry standard for the mass production and quality inspection of electronic circuit boards, based on design considerations to ensure productivity and alignment. First, Pick & Place equipment performs the task of selecting and placing electronic components onto a substrate; components aligned in a straight line simplify the control of the equipment head's movement path and rotation axis, thereby simultaneously improving equipment speed and precision. Furthermore, in the case of Automated Optical Inspection (AOI) equipment, if the orientation of electronic components is standardized, alignment with inspection algorithms is facilitated, improving the defect detection rate and increasing the accuracy of visual comparison and pattern analysis.

[0007] However, this right-angle alignment method is subject to limitations under certain structural conditions. In particular, when a Ball Grid Array (BGA) package is placed on the front of a circuit board, Multilayer Ceramic Capacitors (MLCCs) located on the back can cause design interference problems with typical 0° or 90° alignment. In such situations, a design in which the back MLCCs are placed diagonally, such as at 45° or 135°, is generally adopted.

[0008] As such, in reality, LCR components are positioned at various angles to ensure circuit design and process stability; consequently, a technical challenge exists in which the placement direction of the components affects the accuracy and reliability of the inspection process. Of course, this technical challenge can be resolved by the aforementioned registered patent.

[0009] Meanwhile, since the PCBs used in initial product inspection are temporarily fixed using double-sided tape rather than being soldered, mounted components may be positioned slightly offset from the design-specified center coordinates (XY). This offset is caused by tape tension, precision limitations of pick-and-place mounting equipment, and environmental factors; generally, depending on the size of the component, an error of tens to hundreds of micrometers can occur within an acceptable range.

[0010] However, in the presence of such errors, conventional LCR measuring devices are designed to make contact with the probe based solely on design reference coordinates; consequently, even when the actual component position is slightly off-center, the device fails to make accurate contact with the pad, leading to measurement failures or misjudgments as "poor measurement."

[0011] In particular, in the SMT process, as soldering proceeds, the component tends to automatically return to the correct pad center due to surface tension and solder position. Therefore, even though a small gap in the initial product state may be a temporary phenomenon that does not affect actual quality, it is classified as a defect in the inspection results, which becomes a problem that simultaneously reduces accuracy and efficiency.

[0012] Consequently, when a part is rotated diagonally and slightly misaligned, it is difficult to make accurate electrical contacts and obtain valid measurements using existing inspection systems, leading to problems such as unnecessary misjudgments, repeated inspections, and delays in quality reviews; therefore, a technical solution is required to address these issues. The problem to be solved

[0013] The present invention has been devised to solve the problems described above, and its purpose is to provide a PCBA initial product inspection method and apparatus capable of performing valid electrical measurements based on corrected coordinates even when a component temporarily attached with double-sided tape deviates from the design reference coordinates.

[0014] Another objective of the present invention is to provide a PCBA initial product inspection method and apparatus capable of automatically tracking the actual position of a component, performing multiple measurements not only at reference coordinates but also at deviation coordinates, and determining valid values ​​among them to provide accurate inspection results.

[0015] Another objective of the present invention is to provide a PCBA initial product inspection method and apparatus capable of performing precise electrical characteristic measurements regardless of direction for electronic components arranged at various angles such as 0°, 45°, 90°, and 135°. means of solving the problem

[0016] As a means to achieve the aforementioned objective, the present invention provides a method for inspecting whether a PCBA prototype is defective by contacting a pair of probes to the electrodes at both ends of an electronic component of a PCBA prototype, in which the electronic component is attached with double-sided tape rather than fixed by soldering on a substrate to be inspected, and measuring electrical characteristics, comprising: a step of setting measurement reference coordinates (X, Y) based on the design reference position of the electronic component; a first measurement step of moving a pair of probes upward from the measurement reference coordinates and then lowering them to measure the electronic component; a first determination step of determining the electronic component as normal if the measurement value in the first measurement step is within a normal range, determining it as defective if it is outside the normal range, and determining that the electronic component has deviated from the reference position if no valid measurement value is detected; a first correction coordinate calculation step of calculating a first correction coordinate in a predetermined direction centered on the measurement reference coordinates according to a pre-set error table if the electronic component is determined to have deviated from the reference position in the first determination step; and a second measurement step of moving the probes to the first correction coordinates to measure the electronic component. The present invention provides a PCBA initial product inspection method comprising a second determination step in which, if the measurement value in the second measurement step is within a normal range, the electronic component is determined to be normal, if it is outside the normal range, it is determined to be defective, and if no valid measurement value is detected, it is determined to be out of reference position.

[0017] According to an embodiment, in the first correction coordinate calculation step, a plurality of correction coordinates in the up / down / left / right directions centered on the measurement reference coordinate are calculated according to a pre-set error table, and in the second measurement step, the electronic component is measured by sequentially moving the pair of probes for each of the plurality of first correction coordinates, and in the second judgment step, if there is a valid value within the normal range among the plurality of measurement values ​​in the second measurement step, the component is judged to be normal, and if all measurement values ​​fall outside the normal range, it is judged to be defective.

[0018] According to an embodiment, if it is determined in the second determination step that it deviates from the reference position, the method further includes a second correction coordinate calculation step for calculating a second correction coordinate different from the first correction coordinate according to the error table, a third measurement step for moving a pair of probes to the second correction coordinate to measure the electronic element, and a third determination step for determining the electronic element as normal if the measurement value in the third measurement step is within the normal range, determining it as defective if it is outside the normal range, and determining it as a deviation from the reference position if no valid measurement value is detected, and if it is determined in the third determination step that it deviates from the reference position, the second correction coordinate calculation step, the third measurement step, and the third determination step may be repeated.

[0019] According to an embodiment, if each measurement value is determined to be outside the normal range in the first judgment plate system or the second judgment step, the measurement may be performed by calculating correction coordinates restrictively according to pre-set conditions, or it may be immediately determined to be defective.

[0020] Furthermore, as a means to achieve the aforementioned purpose, the present invention relates to a device for inspecting whether a PCBA prototype is defective by contacting a pair of probes to the electrodes at both ends of an electronic component of a PCBA prototype, wherein the electronic component is attached to a substrate to be inspected by double-sided tape rather than being fixed by soldering, and measuring electrical characteristics, comprising: a pair of transfer devices installed on the upper part of the PCBA prototype; and a pair of probe devices, each of which is transferred to the upper part of the PCBA prototype by the pair of transfer devices and measures the electrical signal of the electronic component of the PCBA prototype, wherein each probe device comprises a rotary motor coupled to one side of the transfer device and arranged vertically, a guide block coupled to be rotatable about the rotation axis of the rotary motor, a servo motor installed on one side of the guide block, a probe block installed to be vertically movable along the guide block by the servo motor, and a probe coupled to the probe block and contacting the electronic component of the PCBA prototype to measure the electrical signal. A PCBA initial product inspection device is provided, comprising: a control unit that sets an initial measurement position of the probe device based on design reference coordinates of the electronic device, and controls the transfer and measurement operation of the probe device by determining whether the measurement value at the reference coordinates is within a normal range and whether a valid measurement value is detected; a correction coordinate calculation unit that, if a valid measurement value is not detected at the reference coordinates or the measurement value deviates from the normal range, calculates a plurality of correction coordinates centered on the reference coordinates based on a pre-stored error table and transmits them to the control unit; and a judgment unit that determines whether the measurement value at the reference coordinates or correction coordinates is within a normal range, determines the electronic device as normal or defective, and determines the electronic device as deviating from the reference position if a valid measurement value is not detected.

[0021] According to an embodiment, a pair of probes of the pair of probe devices can be rotated within a range of 0 to 180° around the rotation axis of the rotary motor according to the arrangement direction of the electronic element, so that they can be in contact with both ends of the electronic element such that the direction of the force acting on both ends of the electronic element in mutually opposing directions with respect to the electronic element is mutually opposite along the same reference line.

[0022] According to an embodiment, when the pair of probes come into contact with the electronic element, the direction of the force acting on both ends of the electronic element by the pair of probes becomes mutually opposite along the same reference line. Effects of the invention

[0023] According to the PCBA initial inspection device of the present invention, correction coordinates are automatically calculated for deviations from the reference position of a component that may occur while temporarily attached with double-sided tape, and repeated measurements are performed at the corresponding coordinates, thereby effectively preventing miscontacts or measurement defects that occurred in existing equipment.

[0024] Furthermore, according to the PCBA initial product inspection device of the present invention, measurement accuracy and reliability can be improved through a logic that automatically determines a valid value among a plurality of measurement values, and precise quality evaluation is possible without misjudging actual good products even in the initial product inspection stage before soldering.

[0025] In addition, according to the PCBA initial product inspection device of the present invention, precise electrical characteristics can be measured regardless of direction for LCR components arranged at various angles such as 0°, 45°, 90°, and 135°, so there is an effect of enabling stable inspection even under circuit design constraints or BGA structures. Brief explanation of the drawing

[0026] FIGS. 1 and FIGS. 2 are photographs showing a PCBA initial sample inspection device according to an embodiment of the present invention. FIG. 3 is a perspective view of a transfer device and a probe device according to an embodiment of the present invention. FIG. 4 is a perspective view of a probe device with a probe installed according to an embodiment of the present invention. FIGS. 5a to 5c are schematic diagrams showing a probe rotating to measure elements arranged at various angles according to an embodiment of the present invention. Figure 6 is a photograph showing a pair of probes each in contact with both ends of an electronic device arranged in a vertical direction. FIGS. 7a to 7c are schematic diagrams for explaining the process of measuring an electronic element according to an embodiment of the present invention. Specific details for implementing the invention

[0027] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, such embodiments are merely intended to provide a detailed description sufficient for a person skilled in the art to easily practice the invention, and the technical concept and scope of protection of the present invention should not be interpreted as being limited only to the following embodiments.

[0028] The present invention relates to a method and apparatus for inspecting whether a PCBA prototype is defective by measuring electrical characteristics through contacting a pair of probes to the electrodes at both ends of an electronic component of a PCBA prototype, wherein the electronic component is attached to a substrate to be inspected using double-sided tape rather than being fixed by soldering. In cases where a valid measurement value is not obtained due to reasons such as displacement of the electronic component or failure of contact, even though the probes have approached the reference coordinates of the electronic component to be measured and attempted to take a measurement, the invention aims to secure a reliable measurement value and make a final determination by performing a re-measurement based on correction coordinates within a pre-set error range.

[0029] As illustrated in FIGS. 1 to 4, a PCBA initial product inspection device (100) according to an embodiment of the present invention may include a base frame (200), a stage (300) installed on the upper side of the base frame (200), a pair of transfer devices (400) provided on the upper side of the stage (300), a pair of probe devices (500) transferred by each transfer device (400), and a pair of probes (560) installed on each probe device (500), and further include a control unit, a correction coordinate calculation unit, and a judgment unit.

[0030] On the upper side of the base frame (200), an upper frame (210) is formed along the perimeter on the left and right sides, the rear, and the upper surface, and on the front and rear of the upper frame (210), a front door (211) and a rear door capable of opening and closing the interior are installed so as to be rotatable in the up and down direction.

[0031] A stand (213) with a monitor (212) installed thereon is provided on one side of the front of the upper frame (210) to check the inspection results, and an input device such as a keyboard (214) is provided on the stand (213). In addition, inspection equipment such as a measuring instrument (215) for inspection is installed on the lower part of the upper frame (210).

[0032] A PCBA prototype for inspection is placed on the stage (300). This PCBA prototype consists of a dummy board (10, see FIG. 6) with various components (20, see FIG. 6) attached by a temporary attachment means such as double-sided tape, and the stage (300) supports the PCBA prototype during the inspection process to prevent movement.

[0033] As shown in FIG. 3, a pair of supports (230) are vertically installed on the upper side of the base frame (200) at a predetermined distance from each other in the left-right direction behind the stage (300), and a pair of base rails (240) that extend long in the left-right direction are installed on the upper side of the supports (230) at a predetermined distance from each other in the front-back direction.

[0034] Additionally, a pair of transfer devices (400) spaced apart from each other at a predetermined distance in the left and right directions are provided on the upper part of the base frame (200), and each transfer device is installed to be movable to the upper part of the PCBA prototype to be inspected along the XY direction. In addition, a pair of probe devices (500) are coupled to one side of each transfer device (400) and are transferred to the upper part of the PCBA prototype by the transfer device (400), and each probe device (500) is provided with a probe (560) that is vertically movable and contacts the component of the PCBA prototype to measure an electrical signal.

[0035] Here, a pair of transfer devices (400) may include a pair of movable rails (410) coupled to slide along each base rail (240) in a left-right direction, and a pair of movable blocks (420) coupled to slide along the inner surface of each movable rail (410). At this time, the movable rail (410) can move in a left-right direction along the base rail (240) by a first drive motor (430) installed at the bottom of the movable rail (410), and the movable block (420) can move in a forward-backward direction along the movable rail (410) by a second drive motor (440) installed at the rear end of the movable rail (410). That is, the movable block (420) can move in the XY-axis direction along the direction of the base rail (240) and the movable rail (410).

[0036] Meanwhile, the probe device (500) is coupled to one side of the moving block (420) and moves together with the moving block (420) in the XY-axis direction, and includes a probe (560) that contacts the component (20) of the PCBA prototype to measure an electrical signal.

[0037] As illustrated in FIG. 4, the probe device (500) may comprise a bracket (510) coupled to one side of a moving block (420), a rotary motor (520) installed vertically on one side of the bracket (510), a guide block (530) rotatably coupled by the rotary motor (520), a servo motor (540) installed on one side of the guide block (530), a probe block (550) that moves up and down along the guide block (530) by the servo motor (540), and a probe (560) provided in the probe block (550).

[0038] At this time, when the guide block (530) is rotated by the rotary motor (520), it is preferable that the rotary motor (520) and the guide block (530) be spaced apart from the moving rail (410) at a predetermined distance so that the guide block (530) does not collide with or interfere with an obstacle.

[0039] Meanwhile, a timing belt (580, see FIG. 10) is connected between a drive pulley (not shown) coupled to the drive shaft of a servo motor (540) and a driven pulley (570) provided at the bottom of a guide block (530), and one side of a probe block (550) is coupled to the timing belt (580), so that when the servo motor (540) operates, the probe block (550) is raised and lowered by the timing belt (580) which operates in a circulating manner.

[0040] At this time, as the guide block (530) is inclined at a predetermined angle with respect to the rotation axis (Z-axis in the drawing) of the rotary motor (520), the probe (560) coupled to the probe block (550) is also inclined at an angle. This is to allow a camera (not shown) installed on the guide block (530) above the probe (560) to accurately capture the contact point between the probe (560) and the element (20) without interference.

[0041] As a pair of probe devices (500) are installed on the upper sides of the base frame (200), the pair of probes (560) for inspecting the PCBA prototype are inclined diagonally toward each other on both the left and right sides of the component (20). As a result, when the pair of probes (560) contact the ends of the component (20) arranged in the vertical direction from the left and right directions as described above, the component (20) temporarily attached to the dummy board (10) may be displaced from its proper position or rotated and twisted in one direction.

[0042] To solve such problems, the present invention is configured such that the probe (560) can rotate within a 180° angle range with respect to the element (20). That is, the probe (560) can rotate together with the guide block (530) within a 180° angle range around the rotation axis of the rotation motor (520) by means of the rotation motor (520) according to the arrangement direction of the element (20), so that a pair of probes (560) can come into contact with both ends of the element (20) in mutually opposing directions with the element (20) in between. At this time, the probe (560) can be selectively rotated to an angle between 0° and 180°, such as 45°, 90°, 135°, etc., thereby enabling precise electrical characteristic measurement regardless of direction for LCR components arranged at various angles such as 0°, 45°, 90°, 135°.

[0043] First, FIG. 5a illustrates a pair of probes (560) in contact with both ends of an element (20) arranged horizontally, and since force is applied to the element (20) in opposite directions along the same reference line (an extension line connecting the contact points of the pair of probes and the element) (L), the element (20) temporarily attached to the dummy board (10) with double-sided tape does not move out of place or become twisted.

[0044] As illustrated in FIG. 5b, when the element (20) is positioned vertically, a pair of probes (560) can be rotated 90° clockwise in the drawing to contact each end of the element (20). At this time, the pair of probes (560) apply force in opposite directions on a reference line (L) passing through the contact points of the probes (560) at both ends of the element (20). Accordingly, when the pair of probes (560) make contact, the element (20), which is temporarily attached to the dummy board (10) with double-sided tape, does not move out of place or become misaligned.

[0045] Additionally, as shown in FIGS. 5c and 5d, when the element (20) is positioned diagonally, a pair of probes (560) can be rotated 40° or 135° clockwise in the drawing to contact each end of the element (20). In this case as well, the pair of probes (560) apply force in opposite directions on a reference line (L) passing through the contact points of the probes (560) at both ends of the element (20), and accordingly, the element (20) temporarily attached to the dummy board (10) with double-sided tape does not move out of place or become misaligned.

[0046] In this way, a pair of probes (560) can measure the element (20) regardless of the direction in which it is positioned, and also prevent the element (20), which is temporarily attached with double-sided tape, from moving out of place or becoming misaligned during measurement.

[0047] Although not illustrated in the drawings, the probe device (500) may be configured to include a transfer device and a probe device. In this case, a pair of probes may be fixedly mounted on a single probe device to simultaneously contact both ends of an electronic component and measure electrical characteristics. This implies that, as in the previously described embodiment, not only are the probes (560) of a pair of probe devices (500) individually transferred and driven, but a form in which a pair of probes are integrally fixed to a single probe device is also included within the technical scope of the present invention.

[0048] A control unit (not shown) plays the role of comprehensively controlling the transfer and measurement operations of the probe device. The control unit analyzes the position information of the electronic component (20) to be inspected by referring to stored design data, calculates the design reference coordinates (X, Y) of the component based on this, and sets the corresponding coordinates as the initial measurement position. If prior design data is not provided to the control unit, the user can manually specify the placement area of ​​the electronic component (20) on the inspection image displayed on the monitor (212) through an input device (e.g., keyboard, mouse, etc.). By accommodating both automatic and manual input methods in this way, it is possible to respond to various inspection environments.

[0049] The control unit controls the operation of the transfer device (400) and the probe device (500) according to a set sequence so that the probe (560) accurately contacts the electrodes at both ends of the electronic device. After contact, the control unit applies an electrical inspection signal (e.g., a constant voltage or frequency signal, etc.) through the probe and collects the response signal to it and analyzes it in real time. Signal analysis can be performed by a built-in control module and can identify electrical characteristics such as the impedance, current-voltage response characteristics, and response frequency bandwidth of the electronic device.

[0050] Furthermore, the control unit determines whether the measurement value at the set reference coordinates is within the normal range and whether a valid measurement value has been detected, thereby controlling subsequent operations such as the movement and measurement of the probe device. That is, if the measurement value is within the allowable range of the reference signal, the corresponding component is determined to be 'normal,' and if it exceeds the reference value or exhibits an abnormal pattern, it is judged to be 'defective.' Additionally, if a valid measurement value is not detected at the set reference coordinates, the control unit automatically calculates correction coordinates by referring to a pre-set error table and controls the probe device to perform subsequent measurements by repeatedly moving it accordingly.

[0051] A correction coordinate calculation unit (not shown) assumes that the electronic component is deviated from the reference position when a valid measurement value is not detected at the reference coordinate, and performs the role of automatically calculating multiple correction coordinates to perform re-measurement accordingly. In this case, the correction coordinate calculation unit calculates multiple correction coordinates centered on the reference coordinate based on a pre-stored error table.

[0052] For example, the correction coordinate calculation unit refers to a pre-stored offset table to calculate multiple correction points in the up / down / left / right directions centered on the reference coordinate (see FIG. 7c), and if necessary, extends the calculation to multiple correction points in the diagonal direction. The error correction range and correction interval applied at this time can be set according to the package size of the electronic device, the distance between electrodes, etc. For example, 4 to 12 correction cells set at ±50μm intervals can be generated.

[0053] The calculated correction coordinates are transmitted to the control unit, which controls the probe device to sequentially move according to the correction coordinates to perform repetitive measurements. As a result, unlike the conventional method that fixedly references only the reference coordinates, valid measurements at various correction positions become possible even when the actual position deviates, thereby significantly reducing the misjudgment rate of normal parts.

[0054] Furthermore, the correction coordinate calculation unit can gradually expand the correction range over multiple stages when repetitive measurements are required, or conversely, calculate additional correction coordinates subdivided into finer intervals. This structure can be particularly useful when inspecting highly integrated circuits or ultra-small components that require high-precision measurements, and it can be extended to apply multiple error tables selectively based on conditions or to algorithms that learn correction error patterns in real-time during inspection.

[0055] A judgment unit (not shown) is responsible for interpreting measurement results and determining the status of an electronic device after a measurement is performed using a probe. Specifically, the judgment unit determines whether the measurement value at a reference coordinate or a correction coordinate is within the normal range and judges the device as 'normal' or 'defective', and judges the device as 'out of reference position' if no valid measurement value is detected.

[0056] First, if an electrical response is measured at the reference coordinates and its value falls within a preset threshold range, the judgment unit determines the corresponding component as 'normal'. In this case, no additional correction measurement is necessary, and the process moves to the next inspection target to attempt a measurement.

[0057] In contrast, even if a response signal exists at a reference coordinate or one or more correction coordinates, if the value exceeds the reference range or shows a discontinuous pattern, the electronic device is judged to have an electrical characteristic 'defect'. For example, if the measured value of a capacitor with a set rating of 10μF ±10% exceeds 13μF, it is judged to be defective because it is a clear exceedance of the specification.

[0058] Meanwhile, if no valid measurement value is detected at any position among the reference coordinate and multiple correction coordinates, it is determined to be 'deviation from reference position' because the electrode of the electronic device may not be in physical contact with the probe, or there may be a positional abnormality such as rotation, tilting, or detachment.

[0059] The judgment unit stores such judgment results in an internal database or inspection history file, and, if necessary, may display the relevant information on the inspection screen through a user interface or transmit it to an external quality control system.

[0060] In addition, the judgment unit may be configured to apply judgment logic by comprehensively considering the number of correction coordinate repetitions transmitted from the control unit, whether valid values ​​are detected, and stability indicators of the measured values ​​(standard deviation, response delay, etc.). In this case, it becomes possible to make high-reliability judgments based on complex judgment criteria, rather than just checking whether a simple threshold is exceeded.

[0061] A method for inspecting a PCBA initial sample according to an embodiment of the present invention as described above will be explained. The PCBA initial sample inspection method may proceed in the following steps.

[0062] Reference coordinate setting step

[0063] For each electronic component subject to inspection attached to the PCBA prototype, the center or reference electrode position of the electronic component is derived based on the PCBA layout design data, and the measurement reference coordinates (X, Y) are established accordingly. These reference coordinates typically correspond to the mounting center of the component or the midpoint between electrodes, and can be determined by considering the shape of the electronic component (e.g., chip type, package type SMD, etc.) and the electrode structure.

[0064] The set reference coordinates are loaded into the control unit, and the movement path and rotation angle of each probe are set so that the probe device can accurately approach according to the reference coordinates. In particular, for rectangular package components such as MLCCs, information on the placement direction (e.g., 0°, 45°, 90°, 135°, etc.) must be included along with the reference coordinates so that the probes can be positioned facing each other in a vertical direction so that they accurately correspond to the electrodes at both ends of the electronic device.

[0065] In addition, the reference coordinates may include information such as the size of the electronic component (length × width × height), the distance between pads, and pitch, in addition to the actual position on the PCB; this information can also be utilized as a reference point for calculating error correction coordinates. The control unit stores the reference coordinate data configured in this manner in memory and retrieves it for each inspection loop to perform reference position access.

[0066] Reference coordinate movement and measurement step (1st measurement step)

[0067] Under the control of the control unit, the probe device is moved to the reference coordinates, and through lifting and lowering movements, the probe contacts the electrodes at both ends of the electronic component to measure electrical characteristics. The measured values ​​are collected in real time through the measurement unit.

[0068] In this case, the probe device is moved to the corresponding position by precise control of the X and Y axis transfer devices and rotated at a predetermined angle around the rotation axis (e.g., 0°, 45°, 90°, 135°, etc.) in accordance with the placement direction of the device. Once rotation alignment is complete, the probe block is raised and lowered along the guide block in the Z-axis direction by the drive of the servo motor, so that the probe comes into perpendicular contact with the electrodes at both ends of the electronic device. At this time, the two probes come into contact facing each other from opposite directions on the same reference line with the device in between, thereby stably supporting the device in a temporarily fixed state so that it does not twist or move when the probes make contact.

[0069] When contact is completed, a measuring unit (e.g., an LCR meter or an internal impedance analyzer) connected to each probe measures the electrical characteristics (capacitance, inductance, resistance value, etc.) of the element. As shown in FIG. 7a, when the element (20) is accurately positioned at a set reference coordinate, a valid electrical response is detected when a pair of probes (560) contact the reference coordinate (C0) set on each probe, and is subsequently determined to be normal or defective. Reference numeral 21 indicates a measurable area for the probe (560), and a valid value can be obtained even if the probe (560) contacts the area (21) rather than both ends of the element (20). Conversely, as shown in FIG. 7b, when the element (20) deviates from the reference coordinate, one or both probes (560) do not contact the measurable area (21) of the element (20), and accordingly, a valid electrical response is not detected. In this case, the measurement is considered a 'failure' and may be classified as out of position or defective in a subsequent judgment stage.

[0070] First judgment stage

[0071] The state of the electronic device is determined by analyzing the measurement value from the first measurement step. In this case, the determination unit applies a determination criterion by referring to the pre-registered reference values ​​of the electronic device (e.g., capacitance, inductance, resistance) and their allowable error ranges.

[0072] For example, if the measured electrical value falls within the device's rated value ± tolerance range (e.g., ±10%, ±20%), the electronic device is determined to be 'normal,' and the inspection process immediately proceeds to the next device. In this case, separate calibration operations or repeated measurements are unnecessary.

[0073] Next, if a measured value exists but falls outside the set tolerance range, the component is determined to be 'defective'. For example, if a capacitor of 10μF ±20% is measured to a value of 15μF or higher, this is considered a non-standard value and may indicate a possibility of electrostatic leakage, internal cracking, or manufacturing defects.

[0074] Meanwhile, if no valid measurement value is detected at all, the component is determined to be in a 'deviation from reference position' state, as there is a possibility that the component has deviated from the reference position as illustrated in FIG. 7b. Conventionally, in such cases, the component was judged to be defective, but in reality, it may be normal, and it may simply mean that the probe did not make accurate contact with both ends of the component at the reference coordinates. Such a situation may occur when a slight positional deviation occurs during double-sided tape fixation, when the probe contacts the outer edge of the pad or the air instead of the component electrode, or when the component is slightly rotated or misaligned on the substrate while not soldered.

[0075] In this case, to prevent misjudgment due to simple positional errors and to ensure inspection reliability, the process proceeds to the correction coordinate calculation step described later to perform re-measurement.

[0076] First correction coordinate calculation step

[0077] If it is determined in the first determination step that the reference position has deviated, a first correction coordinate in a predetermined direction centered on the measurement reference coordinate is calculated according to a pre-set error table. That is, if it is determined that the reference position has deviated because a measurement value at the reference coordinate is not detected, the process immediately switches to the first correction coordinate calculation step. In this step, to account for the possibility of minute component position deviations or probe contact failures, a correction coordinate centered on the reference coordinate is calculated by referring to a pre-set error table (Offset Table). Only one correction coordinate may be calculated, or multiple may be calculated.

[0078] The error table includes predefined correction range and interval data by comprehensively considering the package size of each electronic device (e.g., 0201 inch, 0402 inch, 0603 inch, etc.), electrode area, pad pitch, fixing method (e.g., double-sided tape), rotation tolerance, etc. For example, for an MLCC of size 0603, four correction coordinates can be calculated in the up / down / left / right directions at intervals of 50 μm each in the ±X and ±Y directions, and in addition, four correction coordinates can be calculated in the diagonal direction.

[0079] As a specific example, the following correction coordinates can be calculated centered on the reference coordinates (X, Y). Here, S is the correction distance and can be set in the range of 30 to 100 μm.

[0080] - Up / Down / Left / Right directions: Up(X, Y+S), Down(X, YS), Left(XS, Y), Right(X+S, Y)

[0081] - Diagonal directions: Top-left (XS, Y+S), Top-right (X+S, Y+S), Bottom-left (XS, YS), Bottom-right (X+S, YS)

[0082] In the case of (a) of FIG. 7b, the element (20) is deviated from the set reference coordinate (C0) and is determined to be out of alignment, and as shown in FIG. 7c, a first correction coordinate (C1) is calculated in the up / down / left / right direction. Based on this first correction coordinate (C1), the probe (560) moves to the right and re-measures, and the probe (560) accurately contacts the measurable area (21) of the element (20), thereby obtaining a valid measurement value.

[0083] In addition, the correction interval (S) and the number of repetitions can be flexibly adjusted according to device settings or user conditions, and as the iterative correction progresses, the distance between each correction coordinate can also be gradually reduced.

[0084] The calculated correction coordinates are temporarily stored in memory or a buffer and then sequentially transmitted to the control unit, whereby the probe performs re-contact and measurement at each location. This step constitutes the core logic for effectively preventing normal devices from being misidentified as defective due to positional deviations, particularly by automatically correcting positional deviations of ±10–15% that may occur in devices in a temporarily fixed state.

[0085] First correction coordinate movement and measurement step (second measurement step)

[0086] The probe device is moved to the corresponding position according to the calculated first correction coordinates to measure the element. In an embodiment where multiple first correction coordinates are calculated, repeated measurements are performed by moving sequentially. That is, the probe device is moved sequentially starting from the first coordinate among the multiple correction coordinates calculated in the first correction coordinate calculation step, and repeated measurements are performed for each coordinate under the same measurement conditions.

[0087] The probe device moves to a designated first correction coordinate (e.g., X+50μm, Y-50μm, etc.) according to a control signal from the control unit, then performs a Z-axis downward movement while maintaining the rotation angle and the distance between probes at a constant level, and comes into contact with the electrodes at both ends of the electronic device.

[0088] The measurements performed at this stage are carried out in the same manner as the reference coordinate measurement step, and measurement conditions are automatically set according to the characteristics of electronic components such as capacitance, resistance, and inductance, and the data collected at each correction position is stored independently.

[0089] Since all measurements are performed based on the same sampling period, sensing waveform, and measured voltage, quantitative comparative analysis between data and correction coordinates is possible.

[0090] The second measurement step can proceed in the following order.

[0091] - Move to the first position in the correction coordinate list

[0092] - Collect measurements after Z-axis descent and contact

[0093] - Determining whether valid values ​​are detected

[0094] - If a valid value exists, immediately proceed to the next step.

[0095] - If there are no valid values, move to the next correction coordinate.

[0096] - Repeat the entire correction coordinate cycle or terminate when the maximum number of iterations is reached.

[0097] If a valid value is measured at a specific correction location, the device may be determined to be ultimately normal despite having deviated from the reference location; conversely, if a valid value is not detected at any correction coordinates, it may be determined to be deviated.

[0098] In addition, when valid values ​​are simultaneously detected at multiple locations within the same element during repeated measurements, an algorithm can be applied to select and record the most reliable center or median value, or to take the average value.

[0099] Second judgment stage

[0100] In the second measurement step, the results of multiple repeated measurements performed along the first correction coordinates are comprehensively analyzed by the control unit or the judgment unit, and based on this, a second judgment is made regarding the final state of the corresponding electronic device.

[0101] First, if the value measured at one or more of the multiple first correction coordinates falls within a preset normal range, the electronic device is determined to be normal. This implies that the electrical characteristics of the electronic device itself are satisfactory and supports the conclusion that the measurement was not taken at the reference coordinate merely due to a slight deviation from the temporary fixed position. In this case, since the measured value is within the normal range, the system automatically switches to the next electronic device to be inspected without unnecessary repeated measurements.

[0102] On the other hand, if the measured values ​​at all multiple first correction coordinates are outside the normal range, it is determined to be defective. For example, if all correction position measurements in a resistor of 100Ω ±10% are measured to be 140Ω or higher, it is determined to be defective in electrical characteristics.

[0103] By sequentially measuring all electronic components of the PCBA prototype through this process, the inspection for defects in the PCBA prototype is completed.

[0104] Conditional repeated measurement

[0105] If no valid electrical response is detected at any of the multiple first correction coordinate positions in the second judgment stage, it can be considered that the device is still likely out of reference position, so rather than immediately determining it as defective, it may be considered to re-measure by applying a conditional iterative measurement algorithm.

[0106] In this case, a second correction coordinate can be additionally calculated by applying predefined iteration conditions and extension rules of the error table. The second correction coordinate may be defined to have a wider correction range or a finer interval than the first correction coordinate, for example, by generating additional correction coordinates within a range of ±100μm in the ±X and ±Y directions, or by including fine coordinates interpolated diagonally.

[0107] Based on the second correction coordinate, the same control flow (measurement → judgment) is performed once again. If a valid measurement value is detected as a result, the corresponding component is judged as 'normal'; otherwise, it may be extended to the third correction coordinate according to the repetition condition. In this case, each repetition is considered as an 'increase in the step of the correction coordinate group,' and the system may be set to automatically make the corresponding component 'defective' as a final judgment if the set maximum repetition step (e.g., 3 times) is exceeded.

[0108] The operation flow of repetitive measurement is automated and can be controlled through a cyclic structure of measurement failure → calculation of correction coordinates → position transfer → probe contact → judgment → determination of whether to repeat → final decision.

[0109] Unlike conventional technology that determines the quality of electronic devices based solely on one-time reference coordinate measurements, the above conditional repetitive measurement logic provides a more flexible and precise inspection system that can correct and track installation errors or positional deviations of devices that may occur while they are temporarily attached with double-sided tape in real time.

[0110] Accordingly, even if a normal part is not detected by measurement at the reference coordinates or falls outside the error range, it can be accurately determined as normal if its normal electrical characteristics are confirmed through repeated correction measurements; thus, unnecessary defect judgments are suppressed, and the error rate is significantly reduced. This serves as an important effect in increasing the reliability of the overall inspection quality.

[0111] Furthermore, the repetitive measurement logic finally determines a part as defective or out of position only when no valid measurement values ​​are confirmed or abnormal values ​​are output at all correction coordinates, thereby enabling the identification and subsequent action of only actual defective parts. This minimizes in-process risks and prevents the loss of good parts.

[0112] In addition, since repeated measurements are automatically controlled according to a pre-set maximum number of repetitions or correction depth, it is possible to prevent situations where inspection time is excessively delayed due to more repeated measurements than necessary, and enables efficient control and automatic optimization of inspection time.

[0113] Finally, since this repetitive inspection logic is automatically executed through in-device control algorithms, high-precision repetitive measurements can be performed in real time without operator intervention, thereby improving the level of inspection automation on the production line.

[0114] Although embodiments of the present invention have been described above, those skilled in the art to which the present invention pertains may make various modifications without departing from the scope of the claims of the present invention. Accordingly, the scope of protection of the present invention should be determined by the contents described in the appended claims, and all technical ideas within the equivalent scope should also be interpreted as being included within the scope of rights of the present invention. Explanation of the symbols

[0115] 10 : Dummy board 20 : Component 100: PCBA Initial Sample Inspection Device 200: Base Frame 220 : Guide rail 230 : Support 240 : Base Rail 300 : Stage 340 : Fixed frame 350 : Moving frame 400 : Transfer device 410 : Moving rail 420 : Moving block 430 : First drive motor 440 : Second drive motor 500 : Probe device 510 : Bracket 520 : Rotary motor 530 : Guide block 540 : Servo motor 550 : Probe Block 560 : Probe

Claims

Claim 1 A method for inspecting whether a PCBA prototype is defective by contacting a pair of probes to the electrodes at both ends of an electronic component of a PCBA prototype, wherein the electronic component is attached with double-sided tape rather than being fixed by soldering on a substrate to be inspected, and measuring electrical characteristics, comprising: a step of setting measurement reference coordinates (X, Y) based on the design reference position of the electronic component; a first measurement step of moving the probe to the measurement reference coordinates to measure the electronic component; a first determination step of determining the electronic component as normal if the measurement value in the first measurement step is within a normal range, determining it as defective if it is outside the normal range, and determining that the electronic component has deviated from the reference position if no valid measurement value is detected; a first correction coordinate calculation step of calculating a first correction coordinate in a predetermined direction centered on the measurement reference coordinates according to a pre-set error table if it is determined to have deviated from the reference position in the first determination step; and a second measurement step of moving the probe to the first correction coordinates to measure the electronic component. A PCBA initial product inspection method comprising a second determination step in which, if the measurement value in the second measurement step is within a normal range, the electronic component is determined to be normal, if it is outside the normal range, it is determined to be defective, and if no valid measurement value is detected, it is determined to be out of reference position. Claim 2 A PCBA initial product inspection method according to claim 1, wherein in the first correction coordinate calculation step, a plurality of correction coordinates in the up / down / left / right directions centered on the measurement reference coordinate are calculated according to a pre-set error table, and in the second measurement step, a pair of probes are sequentially moved for each of the plurality of first correction coordinates to measure the electronic component, and in the second judgment step, if there is a valid value within the normal range among the plurality of measurement values ​​in the second measurement step, the component is judged to be normal, and if all measurement values ​​are outside the normal range, it is judged to be defective. Claim 3 A PCBA initial product inspection method according to claim 1, wherein if a deviation from a reference position is determined in the second determination step, a second correction coordinate calculation step for calculating a second correction coordinate different from the first correction coordinate according to the error table; a third measurement step for moving a probe to the second correction coordinate to measure the electronic component; and a third determination step for determining the electronic component as normal if the measurement value in the third measurement step is within a normal range, determining it as defective if it is outside the normal range, and determining a deviation from a reference position if no valid measurement value is detected, wherein if a deviation from a reference position is determined in the third determination step, the second correction coordinate calculation step, the third measurement step, and the third determination step are repeated. Claim 4 A PCBA initial product inspection method according to claim 1, wherein, in the first or second judgment step, if each measurement value is determined to be outside the normal range, a correction coordinate is calculated restrictively according to a pre-set condition to perform the measurement, or the result is immediately determined to be defective. Claim 5 A device for inspecting whether a PCBA prototype is defective by contacting a pair of probes to the electrodes at both ends of an electronic component of a PCBA prototype, wherein the electronic component is attached with double-sided tape rather than being fixed by soldering on a substrate to be inspected, and measuring electrical characteristics, comprising: a pair of transfer devices installed on the upper part of the PCBA prototype; a pair of probe devices each transferred to the upper part of the PCBA prototype by the pair of transfer devices and measuring the electrical signal of the electronic component of the PCBA prototype, each comprising a rotary motor coupled to one side of the transfer device and arranged vertically, a guide block coupled to be rotatable about the rotation axis of the rotary motor, a servo motor installed on one side of the guide block, a probe block installed to be vertically movable along the guide block by the servo motor, and a probe coupled to the probe block and contacting the electronic component of the PCBA prototype to measure the electrical signal; and a device for setting an initial measurement position of the probe device based on the design reference coordinates of the electronic component and determining whether the measurement value at the reference coordinates is within a normal range A PCBA initial product inspection device comprising: a control unit that controls the transfer and measurement operation of the probe device by determining whether a valid measurement value is detected; a correction coordinate calculation unit that, when a valid measurement value is not detected at the reference coordinate or the measurement value deviates from the normal range, calculates a plurality of correction coordinates centered on the reference coordinate based on a pre-stored error table and transmits them to the control unit; and a judgment unit that determines whether the measurement value at the reference coordinate or the correction coordinate is within the normal range to determine the corresponding electronic component as normal or defective, and determines the corresponding electronic component as deviating from the reference position when a valid measurement value is not detected. Claim 6 A PCBA initial product inspection device according to claim 5, wherein a pair of probes of a pair of probe devices can be rotated within a range of 0 to 180° around the rotation axis of the rotary motor according to the arrangement direction of the electronic element, so that the direction of the force acting on both ends of the electronic element in mutually opposing directions with respect to the entire electronic element is in mutually opposite directions along the same reference line. Claim 7 A PCBA initial product inspection device according to claim 5, characterized in that when the pair of probes contact the electronic element, the direction of the force acting on both ends of the electronic element by the pair of probes is mutually opposite along the same reference line. Claim 8 A device for inspecting whether a PCBA prototype is defective by contacting a pair of probes to the electrodes at both ends of an electronic component of a PCBA prototype, wherein the electronic component is attached with double-sided tape rather than being fixed by soldering on a substrate to be inspected, and measuring electrical characteristics, comprising: a transfer device installed on the upper part of the PCBA prototype; a probe device that is transferred to the upper part of the PCBA prototype by the transfer device and measures the electrical signal of the electronic component of the PCBA prototype, and which serves as a probe device comprising: a rotary motor coupled to one side of the transfer device and arranged vertically; a guide block coupled to be rotatable around the rotation axis of the rotary motor; a servo motor installed on one side of the guide block; a probe block installed to be vertically movable along the guide block by the servo motor; and a pair of probes coupled to the probe block and contacting the electronic component of the PCBA prototype to measure the electrical signal; and a device for setting an initial measurement position of the probe device based on the design reference coordinates of the electronic component, and determining whether the measurement value at the reference coordinates is within a normal range and whether a valid measurement value has been detected. A PCBA initial product inspection device comprising: a control unit that controls the transfer and measurement operations of the probe device by making a judgment; a correction coordinate calculation unit that, when a valid measurement value is not detected at the reference coordinate or the measurement value deviates from the normal range, calculates a plurality of correction coordinates centered on the reference coordinate based on a pre-stored error table and transmits them to the control unit; and a judgment unit that determines whether the measurement value at the reference coordinate or the correction coordinate is within the normal range, determines the electronic component as normal or defective, and determines the electronic component as deviating from the reference position when a valid measurement value is not detected.

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