JP4885765B2 - Inspection apparatus and inspection method - Google Patents

Description

  The present invention relates to an inspection apparatus capable of inspecting a wiring (for example, a wiring pattern of a circuit board) that connects one specific part (for example, a bump of a circuit board) and another specific part (for example, an external connection terminal of the circuit board), and It relates to the inspection method.

  As this type of inspection apparatus, an inspection apparatus (substrate inspection apparatus) disclosed in Japanese Patent No. 2994259 is known. This inspection apparatus is a circuit board inspection apparatus for testing the quality of a conductive path in a circuit board provided with an electrode terminal group having an interval that can be individually contacted and a narrow-pitch conductive path row connected to the electrode terminal group. A contact probe group connected in contact with each of the electrode terminal groups, a sensor electrode having a facing surface facing the surface of the circuit board and provided with a shield for interfering with the radiation wave, and a sensor The opposing surface of the electrode is brought close to the conductive path array in a non-contact manner, the probe is brought into contact with an arbitrary first electrode terminal of the electrode terminal group, and an inspection signal including an AC component is supplied. The circuit board by evaluating means for supplying a ground potential by bringing another probe into contact with the second electrode terminal other than the electrode terminal and a signal of the radiated wave detected by the opposing surface of the non-contact sensor electrode Discriminating means for discriminating whether or not there is a defect, the opposing surface of the sensor electrode has a length that can cover the conductive path row in the row direction, and the shield radiates from the conductive path on the first electrode terminal side. It arrange | positions and is comprised so that it may interrupt that the radiated wave to reach | attain the opposing surface of a sensor electrode.

According to this inspection apparatus, since non-contact probing is formed on the inspection target electrode (group) on the narrow pitch side of the conductor pattern and physical contact is unnecessary, disconnection of a flexible substrate having a narrow conductor pattern, etc. In the substrate inspection, it is possible to eliminate the difficulty of conventional blowing by the contact probe, and to satisfy more stringent test requirements.
Japanese Patent No. 2994259 (pages 2, 6 and 1)

  However, the above inspection apparatus has the following problems. That is, in this inspection apparatus, when the arrangement of sensor electrodes (non-contact sensor electrodes) that are brought close to each other in a non-contact manner with respect to the conductive path row is changed, it is formed between the conductive path row to be inspected and the sensor electrode. The capacitance value of the coupling capacitance changes, and the level of the signal detected by the sensor electrode also changes due to the change in the capacitance value. For this reason, this inspection apparatus has a problem that the inspection becomes unstable and it is difficult to perform an accurate inspection.

  Further, in this inspection apparatus, a conductive path row (first electrode) to be inspected is supplied by supplying a ground potential to a conductive path row (connected to the second electrode terminal) that is not an inspection target. That are connected to the terminal). However, the configuration itself for supplying the ground potential individually to the conductive path row not to be inspected is complicated, and the sensor electrode is to be inspected even if the ground potential is supplied to the conductive path row not to be inspected. As a result, the inspection signal supplied to the first electrode terminal also flows through the coupling capacitance through the conductive path row not to be inspected. For this reason, this inspection apparatus also has a problem that accurate inspection is difficult as a result of not being able to completely eliminate the influence of the conductive path row that is not the inspection target.

  The present invention has been made in view of such a problem, and a main object of the present invention is to provide an inspection apparatus and an inspection method capable of accurately inspecting wiring such as a wiring pattern formed on a circuit board.

  In order to achieve the above object, an inspection apparatus according to claim 1 is an inspection apparatus capable of inspecting a wiring connecting one specific part and another specific part, and charging device for charging the one specific part; A discharge gap that is connected to the other specific part and discharges the electric charge charged in the one specific part via the wiring, and a current flowing through the wiring by the discharge is measured and measured. And a processing unit for inspecting the wiring based on the current.

  According to a second aspect of the present invention, in the inspection apparatus according to the first aspect, the processing section inspects the wiring based on the measured peak value of the current.

  According to a third aspect of the present invention, in the inspection apparatus according to the first aspect, the processing unit inspects the wiring based on the measured current waveform.

  The inspection method according to claim 4 is an inspection method for inspecting a wiring connecting one specific part and another specific part, wherein the one specific part is charged by using a charging device and the one specific part is charged. The electric charge charged in the part is discharged through the wiring and the discharge gap, the current flowing through the wiring by the discharge is measured, and the wiring is inspected based on the measured current.

  According to the inspection apparatus according to claim 1 and the inspection method according to claim 4, by using the charging device, for example, circuits arranged in parallel at a fine pitch such that a predetermined potential cannot be individually applied using a probe or the like. One specific portion such as a plurality of bumps on the substrate can be reliably charged and the same potential can be applied. In addition, as a result of being able to apply the same potential to all one specific part, the potentials of other specific parts such as wiring patterns and external connection terminals connected to one specific part other than the inspection target are also the same at the same time An electric potential can be applied. Therefore, according to this inspection apparatus and inspection method, unlike a conventional inspection apparatus, a special mechanism for supplying a ground potential or the like to wiring other than the wiring to be inspected can be made unnecessary. The configuration can be simplified. In addition, according to the inspection apparatus and the inspection method, since the capacitive coupling is not used when applying (supplying) the potential, the situation where the inspection becomes unstable due to the change in the capacitance value of the coupling capacitance is surely avoided. Therefore, an accurate inspection can be performed.

  Further, according to the inspection apparatus and the inspection method, by using the discharge gap, with respect to the wiring that is not broken, the discharge is uniquely determined under a certain condition, that is, the product specification of the discharge gap. Since a current due to discharge (discharge current) can always be generated under a condition where a voltage is applied, wiring inspection can be performed more accurately based on the discharge current generated under a certain condition.

  According to the inspection apparatus of the second aspect, it is possible to easily determine whether or not the wiring to be inspected is normal by inspecting the wiring based on the measured peak value of the current.

  According to the inspection apparatus of claim 3, by inspecting the wiring based on the measured current waveform, for example, the original peak value of the discharge current (the peak value generated immediately after the start of discharge) becomes the reference value. Even if wiring does not reach the peak due to noise superposition, the wiring can be detected more accurately without misjudging that the peak value exceeds the reference value. it can.

  The best mode of an inspection apparatus and an inspection method according to the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, a plurality of bumps 1 (one specific portion in the present invention) are formed on one surface 4 a as an inspection object of the inspection apparatus, and correspond to the plurality of bumps 1. An external connection terminal 2 (another specific part in the present invention) is formed on the other surface 4b, and a wiring pattern (an example of wiring) 3 that connects each bump 1 and each external connection terminal 2 one-to-one is provided. A description will be given by taking as an example a circuit board 5 that includes a substrate body 4 formed inside (and on the surface) and can be mounted on a surface 4a of the substrate body 4 with a bare chip IC (not shown) by flip chip mounting. In recent years, bare chip ICs are constructed by forming an extremely large number of terminals in a region having a small area due to a drastic improvement in the degree of integration. For this reason, the bumps 1 of the circuit board 5 are also arranged side by side in a narrow area at the same fine pitch as that of the terminals of the bare chip IC (for example, a pitch of 0.2 mm or less).

  As shown in FIG. 1, the inspection device 11 includes a charging device 12, a static elimination device 13, a detection probe 14, a scanner unit 15, a discharge gap 16, a current detection unit 17, a storage unit 18, a processing unit 19, and a display unit 20. The inspection method according to the present invention is implemented so that the connection state of each wiring pattern 3 on the circuit board 5 can be inspected.

  The charging device 12 operates when the control signal S1 is input, and is at least one of positive ions (positive ions) and negative ions (also referred to as “ions” unless otherwise distinguished) (this example). Then, only + ions) are generated, and air (an example of a gas) P including the generated ions is sent toward the circuit board 5 through the duct 12a. With this configuration, as will be described later, the charging device 12 can charge all the bumps 1 of the circuit board 5 to a positive potential and raise them with time while keeping their potentials (DC potentials) Vt uniform. . As an apparatus for charging an object to one polarity, for example, there is a charge master (such as a power supply CH-20, an electrode pinner linear, etc.) manufactured by Simco Corporation. These apparatuses, for example, charge films to different polarities. It is used for the purpose of sticking together.

  In addition, as the charging device 12, an ionizer (also referred to as a static elimination device) can be employed. In general, an ionizer generates + ions and-ions, neutralizes charged objects with ions of opposite polarity, and generates only one of + ions and-ions. This is a device for charging the object to one of the positive and negative polarities. The ionizer includes a corona discharge type ionizer that generates ions by applying a high voltage to the discharge needle, a soft X-ray type ionizer that generates ions by soft X-rays, and any type of ionizer can be employed.

  The static eliminator 13 is configured by an ionizer as an example, and operates when the control signal S2 is input to neutralize the electric charges charged on the bumps 1 of the circuit board 5. The detection probes 14 are provided in the same number as the external connection terminals 2 of the circuit board 5 and can be connected (contacted) with the corresponding external connection terminals 2 on the circuit board 5 when the circuit board 5 is disposed at the inspection position. Has been. Since each external connection terminal 2 of the circuit board 5 is formed with a sufficiently wide pitch as compared with the bump 1, each detection probe 14 can be connected simultaneously with the corresponding external connection terminal 2.

  As shown in FIG. 1, the scanner unit 15 includes a plurality of switches (the same number as the detection probes 14) 15a. In this case, each switch 15 a has one contact point connected to the corresponding detection probe 14 on a one-to-one basis, and the other contact point connected in common and connected to the discharge gap 16. In addition, the scanner unit 15 shifts each switch 15a to an on state or an off state so that one detection probe 14 specified by the input control signal S3 is connected to the discharge gap 16.

  The discharge gap 16 includes a pair of metal electrodes, and starts a discharge operation when the voltage applied between the metal electrodes reaches a predetermined discharge voltage Vdi. The discharge gap 16 has one of a pair of metal electrodes connected to each switch 15 a of the scanner unit 15 and the other of the pair of metal electrodes connected to a current detection unit 17. It is arranged between the scanner unit 15. As the discharge gap 16, a surge countermeasure component such as “RSG-401-BJ2” manufactured by Okaya Electric Co., Ltd. can be used. In this example, the current detection unit 17 is configured by a shunt resistor (resistance value: R1 (known)) as an example (hereinafter, also referred to as “shunt resistor 17”), and the other metal electrode of the discharge gap 16 and the ground. Connected between. Since the shunt resistor 17 is a current detection resistor, the resistance value R1 is generally defined to be a small value of 1 [Ω] or less, for example.

  The storage unit 18 is configured by a RAM, a ROM, or the like, and stores reference values Ir1 and Ir2 (Ir1> Ir2) for the discharge current I1 used in the inspection process by the processing unit 19 in advance. In this case, the reference value Ir1 is set to a value slightly smaller than the peak value Ip of the discharge current I1 that flows when the normal wiring pattern 3 is connected to the discharge gap 16 when the discharge gap 16 is discharged. . On the other hand, the reference value Ir2 is set to a value sufficiently smaller than the reference value Ir1 so that the generation of the discharge current I1 can be detected. Further, waveform data Di of the discharge current I1 and the like are stored in the storage unit 18 by the processing unit 19.

  The processing unit 19 is configured using an A / D converter, a CPU, and the like (both not shown). Further, the processing unit 19 executes a board inspection process for inspecting the quality of each wiring pattern 3 formed on the circuit board 5. In addition, the processing unit 19 outputs the control signal S1 to the charging device 12, outputs the control signal S2 to the neutralization device 13, and outputs the control signal S3 to the scanner unit 15, so that the charging device 12, the neutralization device 13 and The operation of the scanner unit 15 is controlled. In addition, the processing unit 19 causes the display unit 20 to display the inspection processing result. The display unit 20 is configured by a monitor device as an example.

  Next, the operation of the inspection apparatus 11 and the inspection method will be described with reference to FIGS. In this example, in order to facilitate understanding of the invention, each resistance component such as a contact resistance between the detection probe 14 and the external connection terminal 2, a resistance of the detection probe 14, and a resistance of the switch 15 a in the ON state is used. The description will be made assuming that the resistance value is zero [Ω].

  In a state where the circuit board 5 is placed at the measurement position (inspection position) in the inspection apparatus 11 and each detection probe 14 is connected to the corresponding external connection terminal 2, the processing unit 19 first removes the control signal S2 from the static electricity The charge output to the device 13 and charged on the circuit board 5 is removed (step 51). Next, the processing unit 19 outputs a control signal S3 to the scanner unit 15 to turn on one switch 15a and shift the remaining switch 15a to an off state, thereby setting one wiring pattern 3 to be inspected. Select (step 52). As a result, the wiring pattern 3 to be inspected passes through the corresponding external connection terminal 2 connected to the wiring pattern 3, the detection probe 14 connected to the external connection terminal 2, and one switch 15 a that has been turned on. And connected to the discharge gap 16.

  Subsequently, the processing unit 19 outputs a control signal S1 to the charging device 12 and starts sending the air P containing a certain amount of + ions to the charging device 12, whereby each bump of the circuit board 5 is started. 1 is charged (step 53). In this case, the delivered air P is almost uniformly applied (sprayed) to all the bumps 1 of the circuit board 5 through the duct 12a. In this state, the surface of each bump 1 is charged according to the amount of + ions contained in the air P, and the potential Vt (potential with respect to the ground) of each bump 1 is from the start of charging. As time elapses, it gradually rises while being maintained in an equipotential state. Further, the processing unit 19 starts measuring the elapsed time t from the start of the charging operation in accordance with the start of the charging operation of the charging device 12 (step 53).

  Next, the processing unit 19 repeatedly executes detection of whether or not the discharge gap 16 has started discharging (step 54). Specifically, the processing unit 19 converts the measurement of the voltage Vi generated in the shunt resistor 17 and the process of converting the measured voltage Vi into the discharge current I1 by dividing the measured voltage Vi by the resistance value R1 of the shunt resistor 17. The comparison between the discharge current I1 and the reference value Ir2 is repeatedly performed to detect whether or not the discharge current I1 is generated, thereby detecting whether or not the discharge gap 16 has started discharging. Further, the processing unit 19 also executes step 54 and also detects whether or not the elapsed time t from the start of the charging operation has reached the predetermined time T1 (step 55).

  When no disconnection occurs in the wiring pattern 3 to be inspected, the voltage between the two metal electrodes of the discharge gap 16 also increases with the increase in the potential Vt of the bump 1, and reaches the discharge voltage Vdi before the lapse of the predetermined time T1. The discharge gap 16 starts to discharge. As a result, the electric charges charged on the bumps 1 connected to the wiring pattern 3 to be inspected are connected in series to the wiring pattern 3, the external connection terminal 2, the detection probe 14, the switch 15 a, the discharge gap 16, and the shunt resistor 17. By moving to the ground via the path, the discharge current I1 flows through this series path as shown in FIG. Further, as shown in FIG. 2, the discharge current I1 suddenly rises beyond the reference value Ir2 and reaches a peak, and then the capacitance value of the stray capacitance formed between the bump 1 and the ground, It gradually decreases to zero with a time constant defined by the resistance value of the wiring pattern 3 and the series combined resistance value of the resistance value R1 of the shunt resistor 17.

  Therefore, since the discharge current I1 always rises exceeding the reference value Ir2, the processing unit 19 detects the discharge start of the discharge gap 16 in step 54 and starts the current measurement process (step 56). In this current measurement process, the processing unit 19 performs measurement of the voltage Vi generated in the shunt resistor 17, conversion of the measured voltage Vi by the resistance value R1 of the shunt resistor 17, and conversion to the discharge current I1. The process of storing the current value of the discharge current I1 obtained in this manner in the storage unit 18 is repeatedly performed until the current value of the discharge current I1 becomes zero, and the waveform data Di for one waveform of the discharge current I1. Is stored in the storage unit 18.

  After the completion of the current measurement process, the processing unit 19 executes a first determination process (step 57). In the first determination process, the processing unit 19 includes the peak value Ip of the waveform data Di for one waveform of the discharge current I1 stored in the storage unit 18, and the reference value Ir1 stored in the storage unit 18. Is compared to determine whether or not the wiring pattern 3 to be inspected is normal. In this case, when the wiring pattern 3 is normal, its resistance value becomes a value close to zero, so that the resistance value of the series path including the wiring pattern 3 substantially matches the resistance value R 1 of the shunt resistor 17. Accordingly, the peak value Ip of the waveform data Di is a value equal to or greater than the reference value Ir1, as indicated by a solid line in FIG. On the other hand, when the wiring pattern 3 is about to be disconnected at a certain portion, the resistance value of the entire wiring pattern 3 is increased from the normal state due to the narrowing of the pattern width of the wiring pattern 3 at this portion. For this reason, the resistance value of the series path including the wiring pattern 3 is a resistance value obtained by adding the resistance value of the wiring pattern 3 to the resistance value R1 of the shunt resistor 17 and is larger than the normal state. Accordingly, the peak value Ip of the waveform data Di becomes a value lower than the reference value Ir1 as shown by a one-dot chain line in FIG. 2, and the time when it becomes zero is longer than that in the normal state.

  Therefore, the processing unit 19 compares the peak value Ip of the waveform data Di with the reference value Ir1, and determines that the wiring pattern 3 is normal when the peak value Ip of the waveform data Di is greater than or equal to the reference value Ir1. When the peak value Ip of the waveform data Di is less than the reference value Ir1, it is determined that the wiring pattern 3 is about to be disconnected, and this determination result is stored in the storage unit 18 in association with the wiring pattern 3. Thereby, the first determination process is completed.

  On the other hand, in a state where the wiring pattern 3 to be inspected is completely disconnected, even if the potential Vt of the bump 1 connected to the wiring pattern 3 rises, the voltage between both metal electrodes of the discharge gap 16 is zero. Maintained in a state. For this reason, when the above steps 54 and 55 are executed, the elapsed time t from the start of the charging operation reaches the predetermined time T1 before the discharge of the discharge gap 16 is started. In this case, the processing unit 19 executes a second determination process (step 58). In the second determination process, the processing unit 19 determines that a disconnection has occurred in the wiring pattern 3 when the elapsed time t reaches the predetermined time T1, and associates the determination result with the wiring pattern 3. To be stored in the storage unit 18. Thereby, the second determination process is completed.

  The processing unit 19 determines whether or not all the wiring patterns 3 have been selected as inspection targets after the completion of the first determination process and the second determination process, and until all the wiring patterns 3 become inspection targets. By repeating the above steps 51 to 59, the inspection is executed for all the wiring patterns 3.

  Finally, the processing unit 19 reads out the inspection result for each wiring pattern 3 from the storage unit 18 and displays it on the display unit 20 (step 60). Thereby, the board inspection processing for the circuit board 5 is completed.

  As described above, in the inspection device 11 and the inspection method, by using the charging device 12, a plurality of circuit boards 5 arranged in parallel at a fine pitch that cannot be individually applied with a predetermined potential using, for example, a probe or the like. The bump 1 can be reliably charged and the same potential Vt can be applied. Further, since the same potential Vt can be applied to all the bumps 1, the same potential Vt can also be applied to the potentials of the wiring pattern 3 and the external connection terminals 2 connected to the bumps 1 other than the inspection target at the same time. Therefore, according to this inspection apparatus 11, unlike the conventional inspection apparatus, a special mechanism for supplying the ground potential or the like to the wiring pattern 3 other than the inspection object can be eliminated, and the apparatus configuration is simplified. Can be In addition, according to the inspection apparatus 11 and the inspection method, since the capacitive coupling is not used when applying (supplying) the potential Vt, it is possible to ensure that the inspection becomes unstable due to the change in the capacitance value of the coupling capacitance. Therefore, an accurate inspection can be performed.

  Further, according to this inspection apparatus 11, by using the discharge gap 16, the wiring pattern 3 in which no disconnection has occurred is uniquely determined under certain conditions, that is, the product specifications of the discharge gap 16. Since the discharge current I1 can always be generated under the condition where the discharge voltage Vdi is applied, the wiring pattern 3 can be more accurately inspected based on the discharge current I1 generated under a certain condition. it can. In addition, according to the inspection apparatus 11, the wiring pattern 3 to be inspected is obtained by comparing the measured peak value Ip of the discharge current I1 with the reference value Ir1 set in advance to inspect the wiring pattern 3. Whether it is normal or not can be easily determined.

  Note that the present invention is not limited to the embodiment of the invention described above, and can be modified as appropriate. For example, in the above-described embodiment, based on the comparison result between the peak value Ip of the discharge current I1 and the reference value Ir1, and the presence / absence of the discharge current I1, the state (the presence / absence of occurrence of disconnection) of the wiring pattern 3 is determined. As shown in FIG. 2, the discharge current I1 is zero until the discharge current I1 becomes zero (discharge end) according to the resistance value of the wiring pattern 3, as shown in FIG. The time changes. Therefore, the inspection of the wiring pattern 3 can also be executed based on the time from the start of the generation of the discharge current I1 to zero. Further, the waveform of the discharge current I1 changes according to the state of the wiring pattern 3. For this reason, the inspection of the wiring pattern 3 can also be executed based on the waveform of the discharge current I1. Specifically, the waveform of the discharge current I1 for the wiring pattern 3 in the normal state is measured in advance as a reference waveform, and a reference waveform range (a range indicated by a broken line in FIG. 2) A including the reference waveform is used as determination data. A configuration in which the inspection of the wiring pattern 3 is executed based on whether or not the waveform of the discharge current I1 that is created and measured is included in the reference waveform range A can also be adopted. According to this configuration, for example, the original peak value Ip of the discharge current Ip (peak value generated immediately after the start of discharge) does not reach the reference value Ir1, but the peak value exceeds the reference value Ir1 due to noise superposition. Since the abnormality of the wiring pattern 3 can be detected without erroneously determining that the wiring pattern 3 is normal, the inspection of the wiring pattern 3 can be performed more accurately.

  Further, in the configuration using an ionizer as the charging device 12, the charge removal device 13 can be omitted because the charge removal function can be used to remove electricity from the circuit board 5. Further, although an example in which a shunt resistor is used as an example of the current detection unit 17 has been described above, it is needless to say that an ammeter may be used.

  In the above-described embodiment, the circuit board (so-called package board) provided with the bumps 1 is described as an example of the inspection target. However, the present invention is not limited to this and is not limited to this. Of course, the present invention can also be applied to inspection of wiring patterns on other circuit boards such as a printed board, a flexible board, and a flat panel display board. Furthermore, the present invention is not limited to a circuit board, and can be applied to inspection of fine pitch flat cable wiring.

2 is a configuration diagram showing a configuration of an inspection apparatus 11. FIG. It is a wave form diagram of discharge current I1. It is a flowchart for demonstrating a board | substrate inspection process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bump 2 External connection terminal 3 Wiring pattern 5 Circuit board 11 Inspection apparatus 12 Charging apparatus 16 Discharge gap 19 Processing part I1 Discharge current Ip Peak value Ir1 Reference value

Claims (4)

An inspection device capable of inspecting a wiring connecting one specific part and another specific part,
A charging device for charging the one specific portion;
A discharge gap that is connected to the other specific part and discharges the electric charge charged in the one specific part via the wiring;
An inspection apparatus comprising: a processing unit that measures a current flowing through the wiring by the discharge and inspects the wiring based on the measured current.   The inspection apparatus according to claim 1, wherein the processing unit inspects the wiring based on a peak value of the measured current.   The inspection apparatus according to claim 1, wherein the processing unit inspects the wiring based on the measured current waveform. An inspection method for inspecting a wiring connecting one specific part and another specific part,
Using the charging device to charge the one specific part,
Discharging the electric charge charged in the one specific part via the wiring and the discharge gap,
Measure the current flowing through the wiring by the discharge,
An inspection method for inspecting the wiring based on the measured current.

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