JP2006220552A - Device and method for inspecting printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and method for inspecting printed circuit boards that can easily find defects, by surely inspecting the conduction of a through hole of a multilayer printed circuit board, the conduction of various patterns and short circuiting. <P>SOLUTION: The device for inspecting the defect comprises moving probe electrodes 4-1 and 4-2, having a plurality of electrodes 41 and 42, juxtaposed to form a row along an inspection object printed circuit board so as to be in contact with measuring points, corresponding to the inspection object printed circuit board 1, moving pad-like planar electrodes 5-1 and 5-2 along the inspection object printed circuit board, while being in contact with the measuring points of the inspection object printed circuit board, and maintaining contact with the measuring points and following the movement of the probe electrodes 41 and 42, and determining the defects between the measuring points, by measuring the electrical continuity between the measuring points of the inspection object printed circuit board, in contact with each of the electrode pin 41 and 42 and the measuring points of the measured printed circuit board, in contact with the pad-like planar electrodes 5-1 and 5-2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printed circuit board inspection apparatus and method for inspecting the quality of a wiring pattern in a printed circuit board manufacturing process, and in particular, inspecting the quality of a wiring pattern including a through hole easily and in a short time. It is related with the inspection apparatus and method which can be performed.

  Conventionally, printed circuit board inspection is known as a checker method using a dedicated jig, a universal checker method using a large number of contact pins formed in a sword mountain shape, a flying probe pin method, an inspection device using image processing, and the like. It has been. Recently, an inspection method using an electric potential distribution method using an electrolytic line sensor is also in the direction of practical use. However, each of these inspection methods has advantages and disadvantages, and recently, various improvements have been made in order to improve the respective defects. However, users are not always happy with each improvement.

  FIG. 12 shows an example of a dedicated jig checker system. In FIG. 12, reference numeral 1 denotes a printed circuit board to be inspected, and reference numeral 100 denotes a jig dedicated to the printed circuit board 1 to be inspected. The jig 100 is for the front side and the back side of the printed board. The front side jig 100 has a pin-like electrode 101 corresponding to the wiring pattern on the front side of the printed board 1, and the back side jig 100 has the printed board 1. A pin-like electrode 101 corresponding to the wiring pattern on the back surface is provided. By pressing the pin-shaped electrodes 101, 101 of the dedicated jigs 100, 100 against the wiring patterns on the front and back of the printed circuit board 1, and measuring the electrical continuity or insulation state between the pin-shaped electrodes 101, the wiring The presence or absence of a pattern cut portion or a short-circuit portion with another wiring pattern is inspected. The pin-shaped electrode 101 of the dedicated jig 100 is arranged at a predetermined mounting position of the pin socket 102 so as to be in contact with one end and the other end of each wiring pattern of the printed circuit board 1 to be measured, and is also supported. Positioned by the plate 103.

  FIG. 13 shows an example of an improved special jig checker system. In this example, the example shown in FIG. 12 is improved so as to be compatible with a case where the wiring pattern of the printed circuit board 1 is made finer. In FIG. 13, reference numeral 200 denotes a dedicated jig for the printed circuit board 1, 201 denotes a pin-shaped electrode, 202 denotes a pin socket, and 203 denotes a densification-compatible probe guide plate. In recent years, the densification of the wiring pattern of the printed circuit board 1 has not stopped, and the dedicated jig checker system shown in FIG. 12 has a limit in narrowing the interval between the pin-like electrodes 101, It is difficult to accurately contact the pin-shaped electrodes 101 without interfering with each other. Therefore, in the example shown in FIG. 13, the tip of each pin electrode 201 is slanted and held by the pin socket 202 and the densification probe guide plate 203 so that the number of pin electrodes per unit area increases. Yes. However, even with this improvement, there is a problem that it is difficult to accurately arrange the pin-shaped electrode 101 at an appropriate position.

  According to the dedicated jig checker system, basically, a fast and reliable test is possible. However, it is necessary to manufacture the dedicated jigs 200 and 200 corresponding to all the specifications or types of printed circuit boards for each specification or type of the substrate to be measured. Therefore, it is suitable for inspection of printed circuit boards that are mass-produced, but in the case of inspection of small-quantity products, there is a problem that the cost burden of jig production increases. The dedicated jig checker method that uses the probe guide plate 203 corresponding to the fine printed circuit board is an idea that makes it easy to pick up the contact point with respect to the fine pattern, but the specification of the printed circuit board to be inspected Or a dedicated probe guide plate corresponding to the type is required, and the problem of high cost cannot be solved.

  The universal checker method is a method using probe electrode pins arranged in a lattice pattern at regular intervals on an XY plane. A printed circuit board is pressed against the grid-like probe electrode pins, and the probe electrode pins are determined so as to come into contact with one end and the other end of the pattern. Based on this, the same test as the dedicated jig checker is performed. This checker system is a state in which contact pins are always erected in a grid pattern like Kenzan over the entire area, so there are pins that do not function at the time of measurement depending on the substrate to be measured, but on the recent miniaturized substrate In some cases, the inspection may be impossible as in the case of the dedicated jig checker. An improved device has also appeared in this universal checker system, and there is also a device for miniaturization. However, there are cases where it is far from the name of universal, and the current situation is that it ends with a function close to that of a dedicated jig checker.

  FIG. 14 is a conceptual diagram of a flying probe checker system. This method was developed to solve the disadvantages of the dedicated jig checker or universal checker, and can deal with fine printed boards with almost no problems. The measurement principle is that the probe electrode pin has a structure that can move to an arbitrary position on the XY plane coordinate, and the probe electrode pin 301 that makes a pair moves individually, between each two points to be measured. This is a method in which the pattern portion is moved and contacted at the same time for inspection. By repeating this operation, the conduction of each pattern is confirmed and a short detection test is performed.

  According to the flying probe checker system, there is a merit that a dedicated jig corresponding to the use and type of the printed circuit board is not necessary, but the time required for the test is long. If the size of the printed circuit board to be inspected becomes large, the test takes time correspondingly. In particular, when trying to test for the presence of shorts at all points to be measured for completeness, the combinations for finding shorts become enormous, and the time required for testing becomes longer. Therefore, it is often the case that only a portion where a short circuit is a concern is tested without performing 100% checking.

  The flying probe checker system has also been improved, and a plurality of movable probe electrode pins have been developed. Each independent pin can simultaneously test different measurement patterns within a range of movement that does not interfere with the movement of other pins. Thereby, compared with what has only one pair of probe electrode pins, a test can be sped up markedly. However, it is difficult to increase the speed to a level where user satisfaction can be obtained. However, it can be evaluated as effective for high-mix low-volume products or when testing prototypes.

  The inspection method described so far is a so-called electrical test method in which inspection is performed by electrical continuity and non-conduction between measurement patterns. In contrast to this electrical test method, the image processing inspection apparatus has photographed a wiring pattern generated on a printed circuit board with, for example, a CCD image sensor after completion of an etching process, which is one process of printed circuit board production. This is an apparatus for processing the image in software and inspecting the quality of the wiring pattern. Although this inspection apparatus has been able to make a considerably fine determination due to recent technological advances, it has a drawback that the inner surface of the through-hole portion cannot be confirmed. A through-hole part means the part of the electrically conductive hole for making each layer of a printed circuit board into a conduction | electrical_connection state. In addition, in the case of a multilayer printed circuit board in which a plurality of printed circuit boards are superimposed, there is a disadvantage that a short circuit that occurs between the inner layers of the circuit boards, that is, between the overlapping surfaces of the printed circuit boards cannot be found. Therefore, this inspection apparatus based on image processing is not usually used for final inspection of a substrate but is used mainly for quality determination inspection after a pattern etching process of an inner layer substrate that does not require confirmation of through-hole conduction.

  More recently, a system has been devised that determines the pass / fail of a substrate to be measured by comparing the measurement difference between the substrate to be measured and its master substrate by measuring the potential distribution using an electrolytic line sensor or the like. According to this method, only a difference from the master substrate is discovered. It is impossible to determine where and what kind of trouble has occurred, and there is an uncertain element in a sense. At the same time, unlike the continuity test in which an actual voltage is applied, depending on the specifications of the board to be measured, for example, it may not be possible to measure accurately for a special structure for the purpose of heat dissipation of the board. Have the disadvantages of

In addition, as a prior art relevant to the present invention, there is a circuit board inspection apparatus including an off-grid adapter, an inspection head including an inspection electrode, and a grid conversion board (for example, see Patent Document 1). Further, the brush-like electrode that contacts the inspection portion of the wiring pattern of the printed circuit board to be inspected, the planar electrode that is insulated from the wiring pattern of the printed circuit board to be inspected, and the space between the brush-like electrode and the planar electrode There is a printed circuit board inspection apparatus having a capacitance detecting means for detecting the capacitance of the printed circuit board (for example, see Patent Document 2).
However, the invention described in Patent Document 1 is characterized by using an off-grid adapter and a grid conversion board, and measurement and inspection itself do not deviate from the conventional example. Although the invention described in Patent Document 2 has a planar electrode, it detects a defect of a printed circuit board by detecting capacitance, and the detection principle of the present invention described below is described. Is completely different.

Japanese Patent Laid-Open No. 5-159821 JP 2002-181870 A

  As described above, various electrical test apparatuses and inspection apparatuses using image processing have their own problems. That is, there are problems that it is difficult to deal with a fine printed circuit board, jig cost is high, processing takes a long time, or an incomplete measurement result is generated.

Therefore, the present invention can inspect and respond to printed boards of different models or specifications relatively quickly, as well as conducting through / short circuit of various patterns as well as through-hole conduction inspection of multilayer printed circuit boards. An object of the present invention is to provide a printed circuit board inspection apparatus and method capable of reliably inspecting and easily detecting defects.
The present invention also provides a low-cost printed circuit board inspection apparatus and method by enabling reduction of the cost of the grid conversion board, although it is necessary to prepare a jig as a grid conversion board for each of various substrates to be measured. The purpose is to provide.

  The present invention moves a probe electrode having a plurality of electrode pins arranged in a row so as to be able to come into contact with a corresponding measurement point of an inspection target printed circuit board along the inspection target printed circuit board. An inspection object in contact with each probe electrode by moving the pad-like planar electrode along the printed circuit board to be inspected while following the movement of the probe electrode while contacting the measurement point and maintaining the contact with the measurement point The most important feature is that a defect between these measurement points is determined by measuring electrical continuity between the measurement points of the measurement points on the printed circuit board and the measurement printed circuit board in contact with the pad-like planar electrode. .

  A pulsed voltage is applied to each electrode pin when each electrode pin is in contact with the corresponding measurement point of the printed circuit board to be inspected, and the current flowing through each electrode pin is then measured to measure the printed circuit board to be measured. The presence or absence of defects can be determined.

By applying a pulsed voltage to each electrode pin in a row in order from the electrode pin at one end of the row to the electrode pin at the other end, and measuring the current flowing through each electrode pin at that time The presence or absence of a defect in the measured printed circuit board may be determined.
Then, the electrode pin that has finished applying the pulse voltage is immediately connected to the ground, and this state is maintained, and the current is measured by the other electrode pins.
The position of the inspection and the inspection result may be specified by determining the position of the probe electrode by illuminating a linear scale arranged along the moving direction of the probe electrode.

(1) In a multilayer printed circuit board, it is possible to inspect where there is no short circuit or disconnection from the appearance, such as the inner layer of the circuit board, that is, the opposing surfaces of the printed circuit boards. By tracking, it is possible to determine at which part a short circuit or other defect has occurred.
(2) The necessity of multilayering the grid conversion board to 6 layers, 8 layers or more is extremely reduced, and a double-sided or 4-layer board is sufficient at most, and the grid conversion board can be simplified. This can reduce the initial cost. Even if it is necessary to make a grid conversion board according to the specifications and type of the substrate to be measured, the configuration of the grid conversion board can be simplified as described above, so the cost required to change the grid conversion board is low. From this point, the initial cost can be suppressed.
(3) A continuity / short-circuit test can be performed in a state where voltage is actually applied to all electric circuits.
(4) The initial investment cost required for introducing the inspection apparatus can be reduced, and the productivity after the inspection apparatus is introduced is improved.

  Embodiments of a printed circuit board inspection apparatus and method according to the present invention will be described below. In FIG. 1, reference numeral 1 is a printed circuit board to be inspected, 2 is a grid conversion board, 3 is an anisotropic conductive sheet, 4-1 upper probe electrode, 4-2 is lower probe electrode, 5-1 and 5 -2 pad-like planar electrodes arranged on the left and upper sides, 5-3 and 5-4 are pad-like planar electrodes arranged on the right and upper sides, 6 is a probe electrode support, 7 is a linear scale, 10 is a feed screw Each is shown. The printed board 1 may have a single-layer configuration, or may be a multilayer printed board in which a plurality of printed boards are stacked. The grid conversion board 2 is a board for easily inspecting the wiring pattern of the printed circuit board to be inspected even if the wiring pattern of the printed circuit board is complicated or miniaturized. Electrodes that are electrically conductive with each other are regularly arranged in a predetermined pattern, and a probe is applied to the electrodes, so that the continuity and short circuit of the wiring pattern of the printed circuit board can be inspected. An example of a grid conversion board is described in Japanese Patent No. 5159821. The anisotropic conductive sheet 3 is a sheet that allows current to flow only from one side of the sheet to the other side for each locally divided range, and is also described in JP-A-5-159821. Has been. In the example shown in FIG. 1, an anisotropic conductive sheet 3 is arranged with a printed circuit board 1 to be inspected sandwiched from both sides, and a grid conversion board 2 is overlaid thereon.

  Each of the probe electrodes 4-1 and 4-2 has a plurality of (many) electrode pins 41 and 42 arranged in a line on the support 6, and this arrangement direction crosses the printed circuit board 1 to be inspected. It is a direction and is arranged over a range sufficient to cross the printed circuit board 1. The support bodies 6-1 and 6-2 have a feed screw 10 screwed into one end side and a guide projection formed on the other end side fitted in the guide groove 45. The feed screw 10 and the guide groove 45 are assembled so as to be parallel to the printed circuit board 1 on the side of the printed circuit board 1 to be inspected positioned in the inspection apparatus. The feed screw 10 is rotatably supported by a pair of support walls vertically rising from the base 50 of the inspection apparatus, and is configured to be rotationally driven by a predetermined rotation angle by an appropriate drive source 8, for example, a stepping motor. Has been. As the feed screw 10 rotates, the electrode pins 41 and 42 are moved together with the supports 6-1 and 6-2. When this moving direction is the X direction, the arrangement direction of the electrode pins 41 and 42 is a direction orthogonal to the X direction, and this direction is the Y direction. Each electrode pin 41, 42 moves while slidably contacting the surface of the grid conversion board 2 along with the movement of the electrode pins 41, 42. Will be in contact.

  Pad-shaped planar electrodes 5-1 and 5-2 are independently provided in the same direction as the moving direction of the probe electrodes 4-1 and 4-2 on the upper and lower sides of the support 6 of the electrode pins 41 and 42, respectively. It is mounted movably. The pad-like planar electrodes 5-1 and 5-2 make surface contact with the electrodes on the surface of the grid conversion board 2 while moving following the probe electrodes 4-1 and 4-2. Therefore, the pad-like planar electrodes 5-1 and 5-2 are formed on the surface of the grid conversion board 2 after the electrode pins 41 and 42 of the probe electrodes 4-1 and 4-2 are in contact with the anisotropic conductive sheet. 3 is electrically connected to all of the wiring patterns of the printed circuit board 1 that are electrically connected to each other. The upper pad-shaped planar electrode 5-1 is electrically connected to the upper surface side wiring pattern of the printed circuit board 1, and the lower pad-shaped planar electrode 5-2 is electrically connected to the lower surface side wiring pattern. In the example shown in FIG. 1, an upper pad-like planar electrode 5-3 and a lower pad-like planar electrode 5-4 are also provided on the opposite side of the movement direction of the electrode pins 41 and 42 across the printed circuit board 1. The drive sources for the pad-like planar electrodes 5-3 and 5-4 are configured in the same manner as the drive sources 8 and 9 for the pad-like planar electrodes 5-1 and 5-1 but are not shown. . The upper pad-like planar electrode 5-3 and the lower pad-like planar electrode 5-4 move so as to follow the electrode pins 41, 42 when the electrode pins 41, 42 are moved backward. , 42 is electrically connected to all the wiring patterns of the printed circuit board 1 that are electrically connected to the electrodes of the grid conversion board 2 after contact. Hereinafter, the movement of the probe electrode and the pad-like planar electrode is referred to as “scan”.

  FIG. 2 shows the relationship among the printed circuit board 1, the conversion board 2, the anisotropic conductive sheet 3, the probe electrode, the support, and the electrode pins in a more specific manner. In FIG. 2, the upper anisotropic conductive sheet is denoted by reference numeral 3-1, the lower anisotropic conductive sheet is denoted by reference numeral 3-2, the upper probe electrode is denoted by reference numeral 4-1, and the lower probe electrode is denoted by reference numeral 3-1. Reference numeral 4-2 represents an upper support body, reference numeral 6-1 represents a lower support body, reference numeral 6-2 represents upper electrode pins, reference numeral 41 represents lower electrode pins, and reference numeral 42 represents lower electrode pins. ing. FIG. 2B shows how the upper probe electrode 4-1 and the upper pad-shaped planar electrode 5-1 are scanned. The electrode pin 41 of the probe electrode 4-1 and the pad-like planar electrode 5-1 scan the conversion grid pattern 2-11 while sliding on the conversion grid pattern 2-11 appearing on the surface of the upper grid conversion board 2-1. It is configured to continue.

  FIG. 3 shows an example of the pad-like planar electrode. In FIG. 3, an elastic body 5-5 having excellent cushioning properties, for example, a cushion material made of urethane is fitted in a rectangular frame 5-7. The upper opening of the frame 5-7 is closed by the pressing plate 5-6, and receives the elastic body 5-5 from above. There is a conductor 5-9 that covers the lower surface of the elastic body 5-5 and reaches the side surface of the frame 5-7, and a top plate 5-8 that covers the side surfaces of the holding plate 5-6 and the frame 5-7 from above. It is fitted. The conductor 5-9 is for contacting each conversion point of the conversion board 2 and electrically connecting it to the ground, and is electrically connected to the conversion point, It is required to have good slidability. Further, the elastic body 5-5 is for making the conductor 5-9 correspond to the unevenness of the conversion point by its cushioning property, so that it can be surely brought into contact with all the conversion points. Therefore, the conductor 5-9 needs to be able to cope with the unevenness of the conversion point, and there is also a method using a conductive mesh in which fine wires of stainless steel are knitted in a net shape to satisfy such conditions.

  By applying a pulse voltage to the electrode pins 41 and 42 at the moment when the electrode pins 41 and 42 are in sliding contact with the conversion grid pattern 2-11, and inspecting conduction and non-conduction between predetermined electrode pins, The quality of the circuit pattern of the printed circuit board 1 is determined. FIG. 4 is a connection diagram of each electrode pin when an instantaneous pulse voltage is applied to the electrode pin of each probe electrode. In FIG. 4, the pad-like planar electrodes 5-1 to 5-4 are always connected to the ground. Therefore, even in the standby position, it is connected to the ground. A switching IC that is controlled to be turned on and off by a timer built in the CPU is interposed in the electric circuit from the DC power source to the probe electrodes 41 and 42, and the timing of voltage application to the electrode pins 41 and 42 is controlled by this switching IC. The In addition, the timing of dropping each electrode pin to ground is controlled by another switching IC that is on / off controlled by a timer built in the CPU. A sensor 12 for detecting that a current has flowed is connected to an electric path for applying a voltage to the electrode pins.

  In FIG. 2B, when the probe electrode 4-1 scans from the left to the right, the left pad-like planar electrode 5-1 moves simultaneously while maintaining a constant interval so as to follow the probe electrode 4-1. . At this time, the pad-like planar electrode 5-3 on the right side remains on standby at the rightmost end. When the probe electrode 4-1 scans from right to left, the movement is reversed. Although the bottom view is omitted in FIG. 2B, each functional component / device is moved exactly the same as the top surface, and the measurement element function / timing is handled in the same manner as the top surface measurement.

  The off-grid tolerance tester is a little more complicated when it is difficult to create a grid conversion board with a board on which a fine BGA-IC or QFP-IC should be mounted on the printed circuit board 1 to be measured. It is necessary to move. This will be explained later.

  An outline of the printed circuit board inspection procedure by the inspection apparatus described above will be described. The continuity / short circuit of the electrical circuit printed on both sides of the measured (inspected) printed circuit board 1 (including the multilayer board) is checked. Here, it is assumed that both the front and back surfaces of the printed circuit board 1 are inspected at the same time, and each circuit test of the substrate to be measured is performed via the grid conversion board 2 and the anisotropic conductive sheet 3. The movement of the functional part of each main device during the test is a process in which a plurality of electrode pins 41 arranged in a direction orthogonal to the X-axis direction are in contact with the grid pattern part 2-11 of the grid conversion board 2 and measured. Thus, a pulsed voltage is applied between the electrode pin 41 and the pad-like planar electrode 5-1 as the ground side electrode, and a current flows between the electrode pin 41 and the pad-like planar electrode 5-1. The presence / absence of the wiring is checked to determine whether the wiring pattern is correct.

  It is determined by a certain algorithm whether it is a regular pattern or there is a defect such as a short circuit. The vertical probe electrode pins 41 arranged in a direction orthogonal to the X direction are scanned in the X direction according to a rule based on a certain principle at the time of scanning. At the same time, the pad-like planar electrode 5-1 follows the X direction so as to follow the movement of the electrode pin 41 at a certain interval. This movement needs to be scanned from end to end at least once according to the size of the substrate 1 to be measured. In the case of a non-fine substrate, a one-way scan from the left to the right may be used. However, a highly accurate measurement result can be obtained by making one reciprocation, and this is desirable. Therefore, the pad-like planar electrode is also installed on the right side of the probe electrode 4-1, that is, on both sides of the apparatus. The electrode pins 41 of each probe function as electric circuit elements in a state where they are independently insulated. The probe electrode 4-1 feeds back position information from the linear scale 7 installed in parallel with the X axis in real time. This position information is also an important determination factor as to whether or not it is a regular circuit pattern. As described above, the quality of the printed circuit board is determined by making full use of the component elements, the operation control of the apparatus, and the determination software.

  The grid conversion board 2 used in the inspection apparatus described above needs to be converted based on a certain conversion algorithm. In order to make a determination when a current flows through the probe electrode without fail, it is necessary to determine the shape of each independent circuit pattern generated on the substrate 1 to be measured and to perform grid conversion. According to this algorithm, it is theoretically possible to perform a short test at all locations as well as disconnection judgment at all locations. Further, it is not always necessary to convert all measurement points to grid points. Therefore, depending on the circuit pattern, it is related to the pattern portion as a circuit terminal that is effective when contacted by the pad-like planar electrodes 5-1 to 5-4, that is, relative to the probe electrodes 4-1 and 4-2. There is a case where there is no problem even if one of the electrodes is off-grid. In that case, it is not necessary to convert it into a grid, and it is only necessary to form a pattern so as to connect the front and back vertically to the grid pattern side of the grid conversion board 2 as it is. This principle element is very useful when, for example, a grid conversion board 2 of a substrate 1 to be measured in which a ball grid array (BGA) type semiconductor integrated circuit component, a CSP (chip size package), or a QFP is present. There is an advantage that the power can be demonstrated and the multi-layered grid conversion board 2 can be saved as much as possible. This also leads to reducing the initial cost burden required for the test for the user of the inspection apparatus.

  When the short detection test is performed according to a soft algorithm developed for application to the apparatus of the present invention, all the pad-like planar electrodes 5-1 to 5-4 are inevitably in contact with each wiring pattern while moving. It has the effect of making it possible. When there is a short, a signal that should not flow is discovered as each electrode pin contacts and passes through the conversion grid pattern 2-11 and can be confirmed thereby.

  Position information in the X direction when the electrode pins 41 and 42 of the probe electrode set perpendicular to the X direction scan in the X direction is fed back from the linear scale 7 installed in parallel with the X axis. The position information may be used as an important factor for the disconnection / short determination algorithm.

  The pad-like planar electrodes 5-1 to 5-4 are portions that become one of the electrodes opposed to the probe electrodes 4-1 and 4-2 when an actual continuity / short-circuit test is performed. The reason why this portion is made to be a pad-like planar electrode is that it can serve as a full contact point at the same time regardless of the positional relationship in any portion on the substrate 1 to be measured. Therefore, the continuity / short-circuit test is made possible by moving the pad-like planar electrode following the movement of the probe electrodes 4-1, 4-2. In other words, when the probe electrodes 4-1 and 4-2 on the high potential side come into contact with one of the contact points 2-11, the probe electrodes 4-1 and 4-2 follow in close proximity. Therefore, the grid pattern 2-11 on the other circuit opposite to a certain probe electrode always comes into contact with the pad-like planar electrode at some position, so that a closed circuit is sequentially formed. The theory of By doing so, it is possible to simplify the apparatus and at the same time simplify the grid conversion board 2. Further, when this idea is developed, the idea that not all independent circuit patterns need to be grid-transformed is reached. In other words, it is sufficient to grid-convert the minimum necessary items. Therefore, the grid conversion board can be prevented from becoming complicated, and the cost can be reduced. The idea of dealing with this off-grid will be described later.

  A learning method can be adopted for the pass / fail judgment of the substrate to be measured. A board that is found to be completely acceptable is measured in advance, and this data is taken in as acceptable data. Next, the board to be measured is inspected, and the obtained data is compared with the acceptable data. If the data is exactly the same, the board to be measured is determined to be acceptable. According to this determination method, it is not necessary to prepare pass / fail determination data, that is, theoretically created data in advance.

  In this way, the printed circuit board is inspected while the probe electrode and the pad-like planar electrode move. However, strictly speaking, the probe electrode and the pad-like planar electrode do not move continuously but move intermittently. When the probe electrode and the pad-like planar electrode move to a predetermined position, the probe electrode is momentarily stopped, and measurement is performed while the probe electrode and the pad-like planar electrode are stopped. Therefore, the movement and the stop are repeated. However, since the stop time is in units of milliseconds (ms), it can be said that it is an intermittent movement or a continuous movement in appearance.

  Next, an additional optional function for further enhancing the functionality of the inspection apparatus will be described. What has been described so far is the case where all the measurement points are subjected to grid conversion, and the probe electrode and the pad-like planar electrode move synchronously. That is, when scanning from the left to the right, the left pad-like planar electrode follows the probe and moves in the left direction so that one of the right-side planar electrodes stops at the far right end of the place. It is configured. The opposite is true when scanning from the right to the left.

  However, if a certain control rule is introduced into the movement of the probe electrode and the pad-like planar electrode, and a certain rule is added at the time of grid conversion, it is possible to eliminate the necessity of on-grid for all conversion points. This can enable simplification of the grid conversion jig board, and hence lower cost. However, since the control of the apparatus becomes complicated, there is a disadvantage that the test time increases. This idea is somewhat thought of at the expense of processing speed, but it would be very useful to have this function as an inspection apparatus. For example, in the case of an extremely fine substrate mounting a BGA-IC with a pitch of 0.5 mm or less, it is very difficult to produce a conventional grid conversion board corresponding to this, but by adopting the above idea, The grid conversion jig board can be simplified to facilitate manufacture. In terms of operation, software only needs to be added, and there is no need for significant modification of the inspection device, and the algorithm can be realized. The determination algorithm will be described later.

  FIG. 6 shows an example of a conversion grid used in the present invention. The example shown in FIG. 6A is an example in which the points 2-11 at which the probe electrodes come into contact are arranged in a lattice pattern in the XY direction. The measurement points of the circuit pattern formed on the printed circuit board to be inspected are led to the points 2-11 arranged in the above-mentioned lattice shape and converted into the lattice shape. Since the electrode pins P1 to Pn of each probe electrode are arranged and fixed in a line on the support, they contact the point while being translated in the X-axis direction while maintaining the Y coordinate position. Strictly speaking, each probe electrode contacts the corresponding position in the X direction while repeating movement and instantaneous stop, and measures whether or not current flows at each contact point. By analyzing the data obtained as a result of the measurement based on a predetermined algorithm, it is determined whether or not there is a short circuit or disconnection. The voltage is applied to each electrode pin of the probe electrode by applying pulses in order from P1 to Pn when moving to the grid point at each position in the X-axis direction. However, after applying a pulse voltage in a short time of several milliseconds, it is immediately dropped to the ground to maintain this state.

  Next, the timing of voltage application to the electrode pins installed on the back side of the printed circuit board to be inspected will be described. After applying the pulse voltage to the electrode pin Pn on the front surface of the printed circuit board, the voltage is applied from the moment to the electrode pin P1 on the back surface to Pn in that order. When one cycle of voltage application from P1 to Pn is completed, the probe electrode moves in the X-axis direction to the next measurement position. The voltage application cycle is repeated at this position, and the measurement of whether or not current flows through each electrode pin is repeated until the end of the printed circuit board is measured. After the measurement is completed up to the end of the board by moving the probe electrode and the pad-like planar electrode in the X-axis direction, the left pad-side planar electrode returns to its original position, and then the probe electrode and the right-side pad-like electrode The planar electrode is moved in the backward direction in the X-axis direction, and at this time, mechanical and electrical control is performed by the same method, and the presence / absence of current is measured at each measurement point.

  In the example of the conversion board shown in FIG. 6B, the measurement points of the printed circuit board to be inspected are converted into contact points arranged in a line in the X-axis direction. As in this example, even if the conversion board 2 does not convert the measurement points into a grid, measurement determination can be made. Reference numeral 25 denotes a conversion point where the electrode pin contacts after grid conversion in the grid conversion board 2. Unlike the example of FIG. 6A, the conversion points 25 are arranged in a straight line in the X-axis direction, and are not arranged in a lattice pattern. According to this example, it is only necessary to have one set of electrode pins that contact each of the conversion points 25. And since the pad-like planar electrode which plays the role as a ground side should just contact each conversion point 25 arrange | positioned in 1 row, a structure can be simplified. However, although the configuration of the pad-like planar electrode as the electrode pin and the ground can be simplified, the conversion board side becomes complicated when viewed as the whole apparatus. That is, as the number of conversion points increases, the number of conversion points 25 increases and the row becomes longer in the X direction, and the routing of the electric circuit for conversion becomes longer and complicated. Accordingly, whether to use a conversion board as shown in FIG. 6B or a conversion board as shown in FIG. 6A may be determined by the user's usage environment.

  Next, the determination algorithm will be described. The determination algorithms include a continuity confirmation determination algorithm and a short (short circuit) discovery algorithm. First, an example of the conduction confirmation determination algorithm will be described. Pattern 1 shown in FIG. 7A is the most basic pattern, and points A and B, which are separated in the X direction and shifted in the Y direction, are electrically connected by a wiring pattern. When the probe electrode moves from the left to the right, that is, in the X direction, and the pad-like planar electrode moves from the left to the right following this, when the electrode pin passes through the point A, if the circuit is normal, the current is Not flowing. When an electrode pin corresponding to a point B different from the electrode pin that has passed the point A passes the point B, the pad-like planar electrode that functions as the ground side electrode contacts the point A, and current is instantaneously generated. . When there is a disconnection on this circuit, no current flows at point B. Therefore, the quality of the circuit pattern can be determined.

  FIG. 7B shows a pattern 2 in which a wiring pattern extending from the point A in the X direction to the point C is separated from the middle to the point B, and the point A and the point C are shifted in the Y direction. Show. In pattern 2, the determination of the continuity between point A and point B can be determined based on the concept of pattern 1 described above. Concerning conduction from point A to point C, if a current is generated when the probe passes through point C, all electrical paths up to point C are conducted. At this time, both the point A and the point B fall to the ground by the pad-like planar electrode.

  In FIG. 7C, the wiring pattern connected to the point A is divided into the B, C, D, and E points in the Y direction, and the positions of the B, C, and D points are shifted in the X direction. Pattern 3 is shown. The continuity determination of this pattern 3 is exactly the same as in the case of pattern 2. Whether the B point, the C point, the D point, and the E point are conducted in the order in which the electrode pins of the probe electrode pass with respect to the leftmost point A. Confirm. If the generation of current can be confirmed at all points in this way, the circuit is confirmed to be conductive at all points.

  FIG. 7D shows a pattern 4 in which the points A and B are the same in terms of the X-axis coordinate value, that is, the points A and B are perpendicular to the X-axis by grid transformation. In this case, the probe Pa in contact with the point A and the probe Pb in contact with the point B are simultaneously in contact timing. The algorithm for confirming the disconnection of the electric circuit is designed to cause a time difference in the timing of applying a voltage to the points A and B. For example, after applying a pulsed voltage to point A and checking continuity, point A is dropped to ground and then voltage is applied to point B. As a result, the conduction of the electric circuit between A and B can be confirmed. During this time, the probe electrode and the pad-like planar electrode do not move. Nonetheless, since the above continuity check is performed instantaneously, it appears that the probe electrode and the pad-like planar electrode are moving. After the probe electrode has moved to another position, voltage cannot be applied to both point A and point B, so determination can be made only at the above timing.

A pattern 5 is shown in FIG. Here, a circuit composed of one pattern composed of points A, B, C, D, E, and X and another pattern electrically independent of this pattern is shown. These two patterns are somewhat complicated circuit examples, each point is shifted in the X-axis direction, and the point A is located at the extreme end on one side. The measurement of the pattern 5 is exactly the same as the conventional measurement method and concept. When the probe electrode passes through the point A, it is confirmed that no current flows even if a voltage is applied to the electrode pin at the point A. Next, it is confirmed that a current flows when the probe electrode passes through points B, C,.
The measurement procedure for each pattern described so far can be similarly applied to the measurement of the wiring pattern on the back side of the printed circuit board.

  FIG. 7F shows a pattern 6 in which wiring patterns formed on the front surface and the back surface of the printed board are electrically connected by a through hole or the like. There are points A and B on the front side, points C and D on the back side, points A and C have the same positional relationship on the X axis, and points B and D are located in the X axis direction. It is off. This pattern may be considered as a modification of the pattern 4 shown in FIG. The electric circuit between point A and point C is confirmed by pulsing the electrode pin (contacted on the back side) that is in contact with point C when the electrode pin in contact with point A falls to the ground. The continuity can be confirmed by applying a voltage and checking whether or not a current flows at that time. Continuity between the points B and C can be confirmed by assuming that the circuit is exactly the same as in the case of the pattern 2.

  Next, a short circuit detection algorithm will be described. Assuming that the electrodes that are electrically connected on the printed circuit board are one group, it is determined whether or not a current flows when the corresponding electrode pin is in contact with the electrode at the front end in the traveling direction of the probe. If a current flows, it can be determined that there is a short-circuit defect. Further, in the direction perpendicular to the moving direction of the probe, that is, the Y direction (the vertical direction of each pattern shown in FIG. 8), a voltage is applied in order from one end side in the Y direction, for example, the upper electrode pin in FIG. The electrode pin is immediately dropped to ground by the switching element described above. When there are a plurality of measurement points at the foremost end in the probe traveling direction, a voltage is applied to the point at the foremost end in the Y direction (for example, the uppermost end in FIG. 8) to observe whether a current flows. If current flows, it is determined that there is a short circuit. The point where the voltage is applied is immediately dropped to the ground, and the current is observed by applying the voltage to the next electrode pin arranged in the Y direction. By doing so, it is possible to determine the presence or absence of short-circuit defects even at a plurality of points arranged in the same row in the Y direction. Hereinafter, with respect to each wiring pattern shown in FIG.

  In FIG. 8A, point A and point B, which are displaced in the X-axis direction and have the same position in the Y-direction, are electrically connected, are displaced in the X-axis direction, and have the same position in the Y-direction. A pattern 1 in which the point and the point D are electrically connected is shown. As shown in FIG. 8 (a), if a short circuit occurs at the point A or a position relatively close to the point A with the circuit connecting the points CD and the circuit connecting the points A and B, the point A is the point C. Current flows when the electrode pin passes through the point A. If there is no short circuit, no current flows. Accordingly, it can be determined that the point A and the point C are conductive by a short circuit.

  FIG. 8B shows the pattern 2. This pattern is a modification of the above-described pattern 1, and the distance between A and B is long in the X-axis direction, the point C is within the length range of AB, and the points B and C are at the same position in the X-axis direction. In this pattern 2, when it is confirmed that a current flows when the electrode pin passes through the point C, there is a short circuit between the electric circuit connecting AB and the electric circuit connecting CD. The electrode pin through which the current flows varies depending on which of the point A and the point C comes into contact with the electrode pin first.

  FIG. 8 (c) shows the same circuit configuration as that of pattern 1, where there is a break at point F of the electric circuit connecting AB, and the electric circuit between A and B at point E, which is closer to point B than point F. The pattern 3 with which the short circuit has arisen in the electric circuit between CD is shown. In the determination when the probe electrode moves from left to right, a short circuit exists at point E even though the circuit between A and B is disconnected at point F. It becomes judgment. That is, immediately after the probe electrode, the pad-like planar electrode moves in the order of C point, A point, B point, and D point, and sequentially contacts these points, so that the electrode pin of the probe electrode reaches B point. In this case, if an electric circuit connecting A-B is to be inspected, a current flows between the electrode pin at point B and the pad-like planar electrode on the ground side, and it is judged as if AB is normally connected. . This phenomenon is a phenomenon that occurs when the disconnection point F is on the left side of the short-circuit point E. When the disconnection point F is on the right side of the short-circuit point E, both the disconnection and the short-circuit can be found by a normal algorithm. In this way, for example, when there is a problem shown in FIG. 8 (c), it is not possible to find a circuit problem only with the one-way scan from left to right in FIG. I understand.

Next, means for solving the above-described determination error and a determination algorithm will be described. The probe electrode and the pad-like planar electrode can detect most of the malfunctions of the circuit, for example, by a one-way scan from left to right. However, there is an exception as shown in FIG. 8C, and there is a limit to increase the accuracy of the inspection only by the one-way scan. Therefore, the above problem can be solved by performing the same inspection when the probe electrode returns from the right to the left, that is, during the backward movement. However, the pad-like planar electrode must also be provided on the right side.When scanning from right to left, the above description has been made by moving the pad-like planar electrode on the right side while following the probe electrode. Perform the inspection exactly as it was. At this time, the pad-like planar electrode on the left side is previously returned to the original position on the left side. In the inspection at the time of the backward movement, since the short-circuit point E is on the near side of the backward movement direction with respect to the disconnection point F, it is detected as if an electric circuit exists between D and B. It turns out that has occurred. Further, since no current flows when the electrode pin passes through the point A, it can be confirmed that a disconnection failure has occurred. The left and right pad-like planar electrodes need to be kept at a position unrelated to the probe electrode except when they play a role, for example, the origin of the pad-like planar electrode determined in advance on the left and right.
In this way, by making the probe electrode reciprocate and measure, it is theoretically possible to find the disconnection / short circuit of all the circuits.

  In the pattern 4 shown in FIG. 8 (d), the AB and CD electric circuits are each formed perpendicular to the X axis and in a straight line, cross the AB electric circuit in the X axis direction, and In this example, an EF electric circuit is formed by being insulated from the electric circuit between A and B. It is assumed that a short circuit occurs at point G in the electric circuit between A and B and the electric circuit between EF. Whether or not a short circuit has occurred between the point B and the point C or between the electric circuit AB and the electric circuit EF can be determined by whether or not a current flows through the point B when a voltage is applied to the point C. it can. Next, if a short circuit occurs at some point, point G between circuit A-B and circuit EF, current flows through point E or point F when voltage is applied to point A. It can be detected that the short circuit is occurring. The same phenomenon occurs regardless of whether the scanning direction is from the left or right, and a short circuit can be detected.

  A pattern 5 shown in FIG. 8E connects an electric circuit in the X-axis direction connecting the points A and B, an electric circuit extending from the point C in the X-axis direction and then bent in a crank shape to the point D, and connecting the points FG. An electric circuit in the X-axis direction, an electric circuit extending from the point I in the X direction and immediately connecting between the points FG, an electric circuit extending in the X direction from the point J in the reverse direction and connecting between the points FG, and a point H connecting to this electric circuit And an electric circuit connecting the electric circuit connecting the points A and B and the electric circuit connecting the points C and D. In this pattern 5, it is assumed that a short circuit E has occurred in the electric circuit connecting the points AB and the electric circuit connecting the points FG. Pattern 5 looks complicated, but even if it is an electric circuit of such a pattern, it corresponds to one of the patterns described so far, and the same algorithm as the judgment algorithm described so far is applied to prevent disconnection or short circuit. Can be determined.

  A short-circuit portion or a disconnection portion of the circuit pattern formed on the printed circuit board can be detected visually or by an image processing method as long as it is a portion that can be visually observed from the outside. However, for example, a short-circuited part or a broken part generated between layers of a multilayer substrate cannot be detected by visual observation or an image processing method. In that respect, according to the inspection apparatus and the inspection method according to the present invention, it is possible to easily detect a short-circuited portion or a broken portion occurring in a portion that cannot be detected by visual observation or an image processing method. Also, at first glance, it seems that there is no short circuit or disconnection, and in fact, it is often the case that a short circuit or disconnection has occurred. However, according to the inspection apparatus and inspection method according to the present invention, such a problem is not caused. Can be found.

The determination algorithm described above is summarized below when the probe electrode scans from left to right.
When each independent wiring pattern of the printed circuit board is observed on the XY plane coordinates, even if the probe electrode is in contact with the leftmost point of each independent wiring pattern and a voltage is applied to the electrode pin, When the wiring pattern is normal, no current flows through the electrode pins. If a current is detected here, the wiring pattern is short-circuited somewhere. Next, when the probe electrode moves to the right, the pad-like planar electrode also moves to the right following this, and the pad-like planar electrode contacts the point at the foremost end in the movement direction. As the probe electrode and the pad-like planar electrode move to the right, the electrode pin sequentially contacts new points, and the pad-like planar electrode contacts all of the points through which the probe electrode has passed. A voltage is applied to the electrode pin at the moment when the electrode pin comes into contact with a new point, and whether or not a disconnection or a short circuit exists can be determined based on whether or not a current flows through the electrode pin. In most cases, this one-way scan can make a sufficient determination, but the accuracy of the pass / fail determination for the entire printed circuit board is not 100%. In order to make the determination result 100% satisfactory, a satisfactory determination result can be obtained by performing the same measurement when the probe electrode is moved backward. The same measurement is performed on the back side of the printed circuit board to determine defects such as disconnection and short circuit.

  Instead of always applying a voltage to each electrode pin in contact with the measurement (detection) point, control is performed so that a voltage having a required length of time is applied in a pulsed manner when necessary. This is because, as already described, it is possible to determine whether the wiring pattern in which the electric circuit is formed in the direction perpendicular to the X axis (Y direction) is good or bad. The order in which the pulse voltage is applied is the order from one end side to the other end side of the electrode pins forming the row.

  The pass / fail of the substrate to be measured is determined based on whether or not a current flows through each electrode pin when it is in contact with the grid point in a state where a voltage is applied to each electrode pin, and whether or not it can be theoretically determined. The grid conversion point at the left end (front end in the probe traveling direction) or the top end (one side end in the Y direction) of each independently circuit does not flow current at any position and timing during probe scanning. If current flows, there will be a short circuit somewhere. At an electric circuit point other than the leftmost end, if no current flows even when a voltage is applied, it is determined that the circuit is disconnected. This criterion can be applied even to a printed circuit board having a seemingly complicated wiring pattern. The same applies to the inspection of the wiring pattern formed on the back surface of the printed circuit board. In the case of a wiring pattern perpendicular to the X-axis direction, it is normal that no current flows when the electrode pin number is smaller. When scanning each electrode pin and the pad-like planar electrode from right to left, the above-mentioned theory is applied to the determination at the rightmost end portion.

  FIG. 9 shows an image of determination of measurement data, and FIG. 9A shows a case where the presence or absence of current generation in the scanning process of the probe electrode is processed in an analog waveform. The horizontal axis is a measurement point at each X-axis coordinate position. P0 and Pn indicate electrode pins at both ends among electrode pins arranged in a row. A plurality of vertical waveforms in the vertical direction means that current is generated at each position. Such an image can also be displayed on a display attached to the inspection apparatus.

  In FIG. 9B, instead of performing analog processing, the presence / absence of current generation at each electrode pin in each X position information is replaced with a binary value of “1” or “0”, and stored in memory in a numerical sequence. The concept is shown. The actual judgment is made based on whether or not there is a difference between this number sequence and the theoretical number sequence in the normal pattern.

  Each measurement point of the printed circuit board to be measured is preferably converted into a lattice shape with a pitch of 2.54 mm or 1.27 mm on the conversion substrate. However, with the recent trend toward miniaturization or miniaturization of electronic devices, it is becoming very difficult to form a grid of all points on a conversion substrate. A BGA type IC is a prime example. This tendency is further progressing, and it can be judged that the tendency becomes stronger in the development of CSP type ICs. In this trend, if all the points of the conversion board are made into a grid, the conversion board itself becomes very multi-layered, so that there is a problem that it becomes very expensive. Even if we can manage it now, we can imagine that it will be difficult unless new technologies are born in the near future. As a countermeasure, we have created an idea that enables the conversion board to be off-grid only in these specific parts. Next, the countermeasure will be described.

  In FIG. 10, a portion surrounded by a square (cross-hatched portion: referred to as a BGA area) is copied directly above the pattern on which the BGA is mounted even on the conversion board (directly under the back surface). Then, a pattern is formed on the conversion substrate. However, since the grid conversion is not naturally performed, it is naturally considered that the electrode pins in that portion cannot always properly contact each point during scanning. However, when grid conversion is performed on the circuit point at the other end derived from this BGA area, it is converted with the introduction of a certain rule, and it is specially controlled to move the electrode pins and pad-like planar electrodes. The above problem can be solved. This will be described below.

  The symbols A, B, and C surrounded by ○ are BGA-IC. Of these, C is an IC mounted from the back side. First, a one-way scan test is performed in the same way as a normal test, regardless of whether or not the conversion substrate has an off-grid conversion portion. In that case, the test on the electric circuit derived (reduced) from the BGA-IC is not perfect. Some electric circuits cannot be determined partially. Therefore, the second round-trip scan is performed. At this time, the movement of the pad-like planar electrode becomes a special movement as described below. The pad-like planar electrodes on the upper and lower sides of the printed circuit board to be inspected move in the same manner, that is, synchronously.

  First, it is assumed that scanning starts from the left to the right. The pad-like planar electrode installed on the right side of the printed circuit board to be inspected is moved to the position of the A2 line corresponding to the right end of the BGA-IC indicated by “A” and stopped as it is. Next, the measurement is started from the left end of the substrate to be measured while the probe electrode and the left pad-like planar electrode move integrally. The measurement method by moving the probe electrode and the left pad-like planar electrode is the same as the measurement method already explained. However, this method mainly causes short-circuits that cannot be detected by normal measurement because they are off-grid. Can be found in. When the probe electrode reaches the A1 line corresponding to the BGA-IC indicated by “A”, the movement and the measurement are temporarily interrupted. The same measurement is performed for other BGA-ICs. Therefore, the measurement related to the “C” and “B” ICs will be described below. The right side pad-like planar electrode starts to move toward the right side again and stops at the position of the C2 line corresponding to the right end of the BGA-IC indicated by “C”. While the right-side pad-like planar electrode is moving, the probe electrode and the left-side pad-like planar electrode remain in a stopped state. Therefore, no measurement is performed during this period. From the point of time when the right pad-like planar electrode moves to the C2 line and stops, the probe electrode and the left pad-like planar electrode start moving from the position of the A1 line to the right, and perform the measurement as described above. And it measures while moving to the C1 line, and when it reaches the position of the C1 line, it stops again. Next, the right pad-like planar electrode starts to move right again and stops at the position of the B2 line corresponding to the right end of the BGA-IC indicated by “B”. The probe electrode and the left pad-like planar electrode start moving again and move while measuring until the probe electrode reaches the B1 line. In this way, movement and measurement from the left side to the right end. However, since the one-way scan as described above lacks accuracy as measurement data, it is desirable to measure the return path in the same manner. In the return path measurement, the left pad-like planar electrode is moved to the left in advance and stopped at a predetermined position, and then the probe electrode and the right pad-like planar electrode are moved toward the left. Even if there are a plurality of BGA-ICs, they may be handled in the same manner. The measurement by the return path control will be described below.

  The measurement by the return path control is performed while scanning the probe electrode and the pad-like planar electrode from the right side to the left side. When the left pad-like planar electrode stops at the position B1 in FIG. 10, scanning is started from the right end of the printed circuit board to be inspected, and measurement is performed. The movement / measurement rules of the left and right pad-like planar electrodes and the probe electrode at this time are the same as the measurement from the left to the right explained above, and the left planar electrode stops first, then An operation of measuring while moving the right plane electrode and the probe electrode is repeated to inspect the front surface of the inspected printed circuit board. Such a reciprocating motion can cope with off-grid BGA.

  Here, another control may be necessary on the control side of the inspection apparatus. The off-grid conversion part has an unstable element in contact when the probe electrode passes. That is, there is a possibility that there is no conversion pad at the position in the Y direction where the probe electrode passes. Alternatively, sometimes there is a concern of measuring data when the electrode pin of the probe electrode is in contact with both of the two conversion pads. Therefore, data measurement should be avoided where there is such a concern. That is, referring to FIG. 10, it is necessary to float (electrically float) the probe electrode from the conversion pad in the BGA area during the first normal scan. This can be easily controlled by incorporating data in advance using operation / determination software for each board. For example, when the probe electrode is located between the line A1 and the line A2 that define the left and right ends of the BGA-IC in the Y direction indicated by “A”, the ends in the X direction of the BGA-IC, that is, the upper and lower ends are defined. Several electrode pins located between the line A3 and the line A4 to be drawn need to be floated. The same applies to other BGA-ICs. During the second scan, it is not necessary to float the electrode pins in this area, but data accumulation and determination of disconnection / short circuit based on the result are not performed. The measurement at the time of the second round-trip scan is data collection only for a derivative circuit such as BGA-IC. This is because the determination has already been completed for data before this scan.

  The following method can be applied as an alternative to the control / measurement method described in paragraphs “0062” and “0063”. This method is characterized by the movement of the probe electrode and the pad-like planar electrode. First, it is assumed that scanning from the left to the right is started. The right pad-like planar electrode is moved to the position of the A2 line and stopped. Next, the probe electrode and the left pad-like planar electrode are moved to the right, and measurement is started. When the probe electrode and the left pad-like planar electrode reach the position of the A1 line, the movement / measurement is stopped and simultaneously returned to the origin position, that is, the left end position of the substrate to be measured. On the other hand, the right side pad-like planar electrode is moved from the position of the A2 line to the right side and stopped at the position of the C2 line. Then restart the measurement. The measurement start position at this time is the left end of the substrate to be measured. Then, when reaching the position of the C1 line while measuring, the probe electrode and the left pad-like planar electrode are returned to the left origin position again. Next, the right side pad-like planar electrode is moved to the position of line B2, and measurement is performed until the position of the B1 line is reached while moving the probe electrode and the left side pad-like planar electrode. The measurement of the entire substrate to be measured is completed by the series of operations described above. That is, in this measurement method, movement from right to left, that is, movement in the backward movement direction and measurement associated therewith are not performed. Whether this method or the above-described method is used is arbitrary, and either method is effective. However, the pass / fail judgment based on the measurement data must be processed in advance with the control method taken into account.

  Next, the grid conversion rule of the electric circuit derived from BGA-IC and a terminal is demonstrated. Grid conversion in the prohibited area shown in FIG. 10 and the prohibited area shown by hatching in the pattern 1 in FIG. 11A is avoided. Even if the BGA-IC exists on the front surface, the back surface is also set as a conversion prohibited area. Referring to FIG. 11A, even if a part of the wiring pattern of the printed circuit board is in the prohibited area, there is no problem if the measurement point that is the end of the wiring pattern is outside the prohibited area. Therefore, in the example of FIG. 11A, there is no problem with the A line, the B line, and the C line. Since all D lines are in the prohibited area, measurement should be avoided. Although it is rare on an actual wiring pattern, the prohibited area indicated by hatching simultaneously becomes a conversion prohibited area for the conversion substrates for the front surface and the back surface.

  Moreover, the pattern 2 shown in FIG.11 (b) is an example with several electric circuit pattern points derived from BGA-IC. In this case, since it is also necessary to avoid grid conversion by distributing to the left and right of the prohibited area, this is the rule.

  Although the measurement by two reciprocations as described above requires much man-hours, there is no way to implement the inspection apparatus and method according to the present invention. In the inspection using the existing technology, it is usual to provide a separate process or perform the inspection using a separate device in order to inspect the BGA portion. As a result, it takes time and processing capacity is limited, so the development of new technology is desired. In applying the present invention, considering the setting of the number of substrates to be inspected, the lifetime, inspection accuracy, etc., prepare a conversion board that is completely on-grid even if it is not cost effective, or low conversion board Whether to focus on pricing depends on the judgment of the user.

In actual use, there is a means for attaching a film-like insulating paper to the off-grid conversion portion of the BGA-IC during the second scan. According to this method, it is not necessary to specially control the movement of the planar electrode during scanning. At first glance, it may be easy to apply or peel off the insulation paper, but it must be handled on the back.
The above-described complicated control reason for the pad-like planar electrode and the concept of setting the conversion prohibited area can be understood by considering the assumption algorithm.

BRIEF DESCRIPTION OF THE DRAWINGS The Example of the printed circuit board inspection apparatus and method concerning this invention is shown roughly, (a) is a top view, (b) is a front view, (c) is a side view. The relationship between a printed circuit board, a conversion board, an anisotropic conductive sheet, and a probe electrode in the above embodiment is shown in an enlarged manner, (a) is a side view, and (b) is a front view. The example of the pad-like plane electrode used for the said Example is shown, (a) is a top view, (b) is side sectional drawing. It is a circuit block diagram which shows notionally the example of the electrical connection of each probe and plane electrode which can be used for the said Example. It is a front view which shows the relationship between the pad-like plane electrode used for the said Example, the printed circuit board of test object, and a probe electrode. It is a top view which shows two examples of the conversion grid used for this invention. It is a connection diagram which shows the various circuit pattern examples for demonstrating the conduction | electrical_connection confirmation determination algorithm in the printed circuit board inspection method concerning this invention. It is a wiring diagram which shows the example of various circuit patterns for demonstrating the short determination algorithm in the printed circuit board inspection method concerning this invention. The image of the measurement data determination by this invention is shown, (a) is an image figure of analog processing, (b) is an image figure of binarized data processing. It is a top view which shows notionally the conversion prohibition area | region by the conversion board in applying this invention. It is a connection diagram which shows the example of the various wiring patterns which exist in the said conversion prohibition area | region. It is a side view which shows notionally an example of the conventional printed circuit board inspection apparatus. It is a side view which shows notionally another example of the conventional printed circuit board inspection apparatus. The other example of the conventional printed circuit board test | inspection apparatus is shown notionally, (a) is a side view, (b) It is a top view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printed board to be examined 2 Grid conversion board 3 Anisotropic conductive sheet 4-1 Probe electrode 4-2 Probe electrode 41 Electrode pin 42 Electrode pin 5-1 Pad-shaped planar electrode 5-2 Pad-shaped planar electrode 5-3 Pad-shaped Planar electrode 5-4 Pad-shaped planar electrode 7 Linear scale

Claims (11)

A probe electrode in which a plurality of electrode pins are arranged in a row so as to be able to come into contact with a corresponding measurement point on the inspection target printed circuit board, and a drive source for moving the probe electrode along the inspection target printed circuit board;
A pad-like planar electrode that is moved along the inspection target printed circuit board while being in contact with the measurement point of the inspection target printed circuit board by another driving source and maintaining the contact with the measurement point;
Control means for controlling the operation of the probe electrode drive source and the pad-like planar electrode drive source,
The control means is configured to control the drive sources so as to move the probe electrode along the printed circuit board to be inspected and to move the pad-like planar electrode following the movement of the probe electrode,
By measuring the electrical continuity between the measurement point of the printed circuit board to be in contact with the electrode pin of each probe electrode and the measurement point of the printed circuit board to be contacted with which the pad-like planar electrode contacts, A printed circuit board inspection apparatus having a determination means for determining a defect.   The printed circuit board inspection apparatus according to claim 1, wherein the probe electrode is moved from one end side to the other end side of the printed circuit board to be inspected in a direction orthogonal to a direction in which the electrode pins are arranged.   2. The print according to claim 1, wherein a grid conversion board is overlaid on the inspection surface of the printed circuit board to be inspected, and the electrode pins of the probe electrode and the pad-like planar electrode move while contacting the conversion grid pattern portion of the grid conversion board. Board inspection equipment.   A linear scale is arranged along the moving direction of the probe electrode, and the grid conversion position information, which is the position information of the probe electrode based on the linear scale, is compared with the determination result, so that a defect at a specific position on the measured printed circuit board can be detected. The printed circuit board inspection device according to claim 1 for determination. Moving a probe electrode having a plurality of electrode pins arranged in a row so as to be able to contact a corresponding measurement point of the inspection target printed circuit board along the inspection target printed circuit board;
The pad-like planar electrode is brought into contact with the measurement point of the printed circuit board to be inspected and moved along the printed circuit board to be inspected following the movement of the probe electrode while maintaining the contact with the measurement point,
By measuring the electrical continuity between the measurement point of the printed circuit board to be in contact with the electrode pin of each probe electrode and the measurement point of the printed circuit board to be contacted with which the pad-like planar electrode contacts, A printed circuit board inspection method characterized by determining a defect.   A pulse voltage is applied to each probe electrode when each electrode pin is in contact with the corresponding measurement point of the printed circuit board to be inspected, and then the current to be measured is measured by measuring the current flowing through each electrode pin. The printed circuit board inspection method according to claim 5, wherein the presence or absence of a substrate defect is determined.   By applying a pulsed voltage to each electrode pin in a row in order from the electrode pin at one end of the row to the electrode pin at the other end, and measuring the current flowing through each electrode pin at that time The printed circuit board inspection method according to claim 5, wherein the presence or absence of a defect in the measured printed circuit board is determined.   8. The printed circuit board inspection method according to claim 7, wherein the electrode pin that has been applied with the pulse voltage is immediately connected to the ground, and the state is maintained and the current is measured by the other electrode pin.   The printed circuit board inspection method according to claim 5, wherein the position of the probe electrode is determined by illuminating a linear scale arranged along the moving direction of the probe electrode, and the inspected position and the inspection result are specified.   6. The printed circuit board inspection method according to claim 5, wherein the presence or absence of a defect in the measured printed circuit board is determined by moving the probe shaft and the pad-shaped planar electrode in one direction.   The printed circuit board inspection method according to claim 5, wherein the presence or absence of a defect in the measured printed circuit board is determined by reciprocal movement of the probe electrode and the pad-like planar electrode.

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