JP2002148298A - Device and method for inspecting circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method for inspecting a circuit board, which can prevent a circuit board from being contaminated by preventing a spark from being generated in a discharge area when the circuit board is inspected, using a discharge phenomenon. SOLUTION: A discharge electrode 53 is arranged opposite a pad part 12a at a specific interval, while covering all pad parts 12a. Consequently, a discharge area DR is formed between the discharge electrode 53 and the pad parts 12a. The rare gas from a rare gas supply part 71 is supplied to a closed space SP, including the discharge area DR to put the discharge area DR in a rare gas atmosphere, so that the oxygen density is zero or is very low. No spark is therefore generated in the discharge area DR, even when discharging is produced in the discharge area DR by giving a potential difference larger than a discharging start voltage between a wire 12 for inspecting a work (circuit board) 10 and the discharge area 53.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an inspection apparatus and an inspection method for inspecting an electrical state of a plurality of wirings formed on a circuit board. In addition, this invention,
Printed wiring boards, flexible boards, multilayer wiring boards,
It can be applied to electrical wiring inspection on various substrates such as glass substrates for liquid crystal displays and plasma displays, and film carriers for semiconductor packages. In this specification, these various wiring substrates are collectively referred to as “circuit boards”.
Called.

[0002]

2. Description of the Related Art A wiring pattern formed of a plurality of wirings is formed on a circuit board, and a large number of inspection apparatuses have been provided to inspect whether or not the wiring pattern is finished as designed. I have. In particular, in recent years, finer wiring patterns have been developed in accordance with the miniaturization and weight reduction of electronic devices, and it may be difficult to directly inspect a wiring for disconnection or short-circuiting of the wiring with a probe. Was. Therefore, instead of this contact method, a non-contact type inspection device using capacitive coupling or a non-contact type inspection device using discharge has been proposed.

As the latter inspection apparatus, for example, Japanese Patent Application Laid-Open
There is an apparatus described in JP-166635A. This device is a device for inspecting disconnection / short-circuit of a metal deposition electrode formed on a glass substrate. The electrode is inspected as follows. That is, in this device, a pair of probes is arranged above the deposition electrode at a predetermined interval (air gap), and a voltage is applied between both probes by a DC power supply. Therefore, by setting this voltage to be equal to or higher than the discharge starting voltage, it becomes possible to conduct electricity by discharge between each probe and the corresponding electrode end, and one probe, one air gap, electrode, and the other from the power supply. A conductive path is formed to return to the power supply via the air gap and the other probe. Therefore, for example, the continuity of the electrode to be inspected can be inspected by arranging probes at both ends of one electrode while opposing each other and detecting the current flowing through the conductive path.

[0004]

However, when a circuit board is inspected by utilizing a discharge phenomenon, the following problems occur. First, when a discharge occurs in air,
A spark may be generated when the discharge occurs. In this case, contaminants such as oxides and nitrides adhere to the surface of the electrode facing the discharge region or the surface of the substrate base, thereby contaminating the circuit board. Inconvenience occurs in mounting electronic components. Therefore, spark generation has become a major obstacle in the practical application of non-contact inspection utilizing the discharge phenomenon.

Further, when a high voltage is applied to the circuit board when using the discharge phenomenon, there is a concern that problems such as dielectric breakdown of the circuit board may occur. Therefore, there is a demand to lower the discharge starting voltage as much as possible. In this regard, in the conventional inspection apparatus, air ions are supplied to the air gap (corresponding to the “discharge region” of the present invention) to improve the conductivity in the air gap, but the circuit board is still inspected. Therefore, a direct current of 500 V must be applied, and a further reduction in the firing voltage is desired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and when inspecting a circuit board using a discharge phenomenon, it is possible to prevent the occurrence of sparks in a discharge region and to prevent contamination of the circuit board. It is a first object of the present invention to provide a circuit board inspection apparatus and method which can be performed.

Further, the present invention provides a circuit board inspection apparatus and an inspection method which can achieve the above first object and further suppress a discharge starting voltage to suppress damage to the circuit board due to discharge. As a second purpose.

[0008]

According to the present invention, there is provided an inspection apparatus for inspecting a plurality of wirings formed on a circuit board. In order to achieve the first object, the inspection apparatus is to be inspected among the plurality of wirings. A discharge electrode that is spaced apart from a part of the wiring, a non-facing part of the wiring to be inspected that does not face the discharge electrode, and a discharge electrode that provides a potential difference greater than or equal to a firing voltage between the discharge electrode and the discharge electrode. A power supply, discharge occurrence detection means for detecting occurrence of discharge in a discharge region sandwiched between the discharge electrode and the inspection target wiring, rare gas supply means for supplying a rare gas to the discharge region, Determining means for determining a conduction state of the inspection target wiring based on a detection result by the occurrence detecting means.

According to the invention having such a configuration, when the wiring to be inspected is in a conductive state, a conductive path is formed from the power supply for discharge to the power supply for discharging via the wiring to be inspected, the discharge region and the discharge electrode. Therefore, discharge occurs in the discharge region. On the other hand, when the inspection target wiring is in a non-conductive state, the conductive path is not formed, and no discharge phenomenon in the discharge region is observed. Therefore, it is possible to determine the conduction state of the inspection target wiring by detecting the occurrence of discharge in the discharge region. Here, in the present invention, a rare gas is supplied to the discharge region, and the discharge region has a rare gas atmosphere filled with the rare gas. In this rare gas atmosphere, since oxygen is zero or extremely low in concentration, no spark is generated even if a discharge phenomenon occurs, and contamination of the circuit board is reliably prevented.

Here, in order to ensure that the discharge region has a rare gas atmosphere, for example, a closed space is formed by surrounding the discharge region and the discharge electrode by a chamber, and the rare gas supply means supplies the closed space to the closed space. What is necessary is just to comprise so that a rare gas may be supplied. Further, an exhaust unit communicating with the chamber and exhausting a gas component present in the closed space out of the chamber is further provided, and before the rare gas supply unit supplies the rare gas to the closed space, A gas component in the closed space may be exhausted out of the chamber by an exhaust unit. By doing so, the discharge region is efficiently replaced with a rare gas atmosphere with a small amount of rare gas.

In order to achieve the second object, the present invention provides a pre-discharge electrode disposed in the closed space and a potential difference between the pre-discharge electrode and the discharge electrode by providing a potential difference between the pre-discharge electrode and the discharge electrode. And a preliminary discharge power supply for generating a preliminary discharge within the power supply. In the invention configured as described above, the preliminary discharge occurs in the closed space including the discharge region, and the discharge starting voltage decreases. For this reason, the potential difference to be applied between the non-facing portion and the discharge electrode can be set low, and damage to the circuit board due to discharge can be suppressed.

[0012] Further, a power supply for preventing erroneous discharge that provides a potential difference lower than a discharge start voltage between the discharge electrode and a wiring other than the wiring to be inspected among the plurality of wirings may be further provided. As described above, a voltage equal to or higher than the discharge start voltage is applied to the wiring to be inspected with respect to the discharge electrode, and a voltage lower than the discharge start voltage is applied to the wiring not to be inspected. In other words, a discharge between the wiring and the discharge electrode, that is, an erroneous discharge is reliably prevented.

An erroneous discharge preventing power supply for generating a voltage lower than a discharge starting voltage, and one of the plurality of wirings is selected as a wiring to be inspected, and the wiring to be inspected is electrically connected to the power supply for discharging. Selecting means for electrically connecting wirings other than the wiring to be inspected among the plurality of wirings to the power source for preventing erroneous discharge, and sequentially switching the wirings to be inspected, Thus, each time the wiring to be inspected is switched, the determining unit may determine the conduction state of the wiring to be inspected. In this case, even if any one of the plurality of wirings is selected as the wiring to be inspected by the selection means, a voltage equal to or higher than the discharge starting voltage is always applied to the wiring to be inspected with respect to the discharge electrode, Since a voltage lower than the discharge starting voltage is applied to the wiring that is not, the erroneous discharge is prevented and the conduction state of each wiring can be inspected with high reliability.

Further, the discharge electrodes may be arranged so as to face all of the wirings and to face a part of each wiring.
Further, the arrangement relationship with respect to each wiring, the electrode shape, and the like are also arbitrary. For example, an electrode formed in a plate shape may be arranged substantially in parallel with the circuit board, or a discharge electrode may be arranged in a plate-like electrode portion arranged substantially in parallel with the circuit board, and It may be constituted by a plurality of protruding electrode portions projecting from the electrode portion toward the circuit board. Further, a conical, pyramidal or block-shaped single electrode can be used.

Further, a method for inspecting a circuit board according to the present invention is an inspection method for inspecting a plurality of wirings formed on a circuit board. In order to achieve the first object, an inspection method among the plurality of wirings is provided. A first step of disposing the circuit board relative to the discharge electrode such that the discharge electrode faces a part of the target wiring, and after the first step, the discharge electrode and the test target wiring A second step of replacing a discharge region sandwiched between the discharge region with a rare gas atmosphere, and a non-facing portion of the inspection target wiring that does not face the discharge electrode after the discharge region is replaced with a rare gas atmosphere. A third step of providing a potential difference equal to or greater than a discharge starting voltage between the discharge electrode and the discharge electrode;
A fourth step of detecting occurrence of discharge in a discharge region sandwiched between the discharge electrode and the inspection target wiring, and determining a conduction state of the inspection target wiring based on the detection result.

In this inspection method, after replacing the discharge region with a rare gas atmosphere, a potential difference equal to or higher than a discharge starting voltage is generated between a non-facing portion of the wiring to be inspected that does not face the discharge electrode and the discharge electrode. Have given. Therefore, as in the above-described apparatus, even if the inspection target wiring is in a conductive state and a discharge occurs in the discharge region, the discharge region is in a rare gas atmosphere and the oxygen concentration is zero or extremely low. Does not occur, and contamination of the circuit board is reliably prevented.

Further, when performing a short-circuit inspection on a plurality of wirings after the inspection of the conduction state, the following configuration may be adopted. That is, first, gas components existing in the discharge region are exhausted. As a result, the discharge gas component formed by the occurrence of the discharge in the continuity test is reliably removed. Then, thereafter, one of the plurality of wirings is selected as a reference wiring, a potential difference is applied between the reference wiring and the other wiring, and a short circuit of the reference wiring is determined.

[0018]

FIG. 1 is a diagram showing one embodiment of a circuit board inspection apparatus according to the present invention. FIG. 2 is a block diagram showing an electrical configuration of the inspection apparatus of FIG. This inspection apparatus is, for example, C4 (= Controlled Colla
This is an apparatus for inspecting a circuit board 10 on which a semiconductor chip can be mounted by a pseudo chip connection (pse chip connection) method. In this circuit board 10, as shown in FIG.
Are formed with a plurality of wirings 12. Each wiring 12 includes a pad portion 12 a provided on one surface of the base substrate 11 corresponding to a pad of a semiconductor chip, a ball grid 12 b provided on the other surface of the base substrate 11, and A conductive portion 12c is provided in the formed hole (= Via) and electrically connects the pad portion 12a and the ball grid 12b. The pad portions 12a are arranged at a narrow pitch corresponding to the pads of the semiconductor chip, while the ball grid 12b is
They are arranged at a wider pitch than 2a. In this embodiment, a case where the circuit board 10 configured as described above is inspected as a work to be inspected will be described. However, the circuit board to which the present invention is applied is not limited to this. Needless to say.

This inspection apparatus is provided with a work holder 21 for holding one circuit board as the work 10. The work holder 21 includes an inspection position (a position shown in FIG. 1) for inspecting the work 10 and a work holder 2.
Loading of the work 10 into 1 and work holder 2
The work driving mechanism is movable between a load / unload position (not shown) for unloading the work 10 from the first position and a control signal from a control unit 30 for controlling the entire apparatus. 22 reciprocates the work holder 21 between the inspection position and the load / unload position.

In this inspection position, a lower jig is arranged below the work 10. The lower jig 40 holds a plurality of conductive spring probes 41 provided corresponding to the ball grids 12 b of the respective wirings 12, a multiplexer 42, and the workpiece 10 while holding the probes 41 and the multiplexer 42. It comprises a lower jig base (not shown) that can move closer to / separate from the lower jig. A lower jig driving mechanism 43 is connected to the lower jig base, and drives the lower jig base toward and away from the work 10 in accordance with a control signal from the control unit 30.

On the other hand, the work 1 positioned at the inspection position
An upper jig 50 is disposed above the “0”. The upper jig 50 includes a chamber 51 formed in a cap shape so as to cover one surface of the workpiece 10, a packing 52 attached to a flange portion of the chamber 51, and a discharge electrode 53 arranged in a recess 51 a of the chamber 51. And a preliminary discharge electrode 54 disposed close to the discharge electrode 53 between the discharge electrode 53 and the inner bottom surface 51b of the chamber 51. These components 51 to 54 are integrally formed with the workpiece 10. It can be moved closer and further away. For this reason, when the upper jig drive mechanism 55 connected to the upper jig 50 operates according to the drive command from the control unit 30 and the upper jig 50 moves close to the work 10 side, as shown in FIG. The packing 52 is sandwiched between the flange portion of the chamber 51 and the outer peripheral edge of the surface of the work 10 and deforms flat. As a result, a closed space SP surrounded by the work 10, the packing 52, and the concave portion 51a of the chamber 51 is formed.

An inlet opening 51c and an outlet opening 51d are provided on the side surface of the chamber 51. A rare gas supply unit 71 is connected to the inlet opening 51c via a solenoid valve 61, and an exhaust unit 72 is connected to the outlet opening 51d via a solenoid valve 62. Therefore, when the electromagnetic valve 62 is opened according to the operation command from the control unit 30 and the exhaust unit 72 is operated, the gas component in the closed space SP is discharged to the outlet opening 51d.
Can be exhausted via In addition, while the electromagnetic valve 61 opens according to an operation command from the control unit 30,
When the rare gas supply unit 71 operates, the inlet opening 51c
, A rare gas component such as argon or neon can be introduced into the closed space SP. As described above, in this embodiment, the rare gas supply unit 71 and the exhaust unit 72 constitute the chamber atmosphere control unit 70, and the gas atmosphere (gas component and gas pressure) in the closed space SP is controlled by the chamber atmosphere control unit 70. Etc.) can be controlled.

In this inspection apparatus, a flat metal electrode made of aluminum, tungsten, rhodium or the like is used as the discharge electrode 53. The flat discharge electrodes 53 are arranged so as to cover all the pad portions 12a so as to face the pad portions 12a and to be separated by a predetermined distance. With this arrangement, a space region is formed between the discharge electrode 53 and the pad portion 12a, and this space region is formed in the discharge region DR as described later.
Becomes Further, as the preliminary discharge electrode 54, a metal plate electrode of aluminum, tungsten, rhodium or the like can be used.

In this inspection apparatus, three types of DC power supplies 81 to 83 are provided. First to third power supply 8
1 to 83 output voltages V1 to V3, respectively, according to commands from the control unit 30. Hereinafter, first and second power supplies 81 and 82 for directly inspecting the conduction / non-conduction state of the wiring.
And a third power supply (power supply for preliminary discharge) 83 for generating a preliminary discharge to lower the discharge start voltage V0.

In the inspection apparatus according to this embodiment, the first
When the voltage V1 of the power supply 81 and the voltage V2 of the second power supply 82 are the following inequalities, V1 <V0 V1 + V2 ≧ V0, where V0 is to generate a discharge between each pad portion 12a and the discharge electrode 53, that is, in the discharge region DR. , Which is a discharge starting voltage required for the above.

Of these power supplies, the first power supply 81 has a positive terminal connected to the negative terminal of the second power supply 82 and one terminal of the multiplexer 42, and a negative terminal connected to the discharge electrode 53. Is electrically connected to Further, the plus terminal of the second power supply 82 is connected to the other terminal of the multiplexer 42 via the current detection unit 90. Therefore, while the output voltages of the first and second power supplies 81 and 82 are set to the voltages V1 and V2, respectively, the switches constituting the multiplexer 42 are switched in response to a selection command from the control unit 30 and a plurality of switches are switched. When one of the wirings 12 is selected, the ball grid 12b of the wiring (inspection target wiring) is selected.
, A voltage (V1 + V2) higher than the discharge starting voltage V0 is applied. As a result, the discharge region DR sandwiched between the pad portion 12a connected to the ball grid 12b and the discharge electrode 53 is formed.
, A second power supply 82, a current detection unit 90, and a multiplexer 4
2. A conductive path is formed to reach the negative terminal of the first power supply 81 via the wiring 12, the discharge region DR and the discharge electrode 53. As described above, in this embodiment, the series power supply including the first and second power supplies 81 and 82 corresponds to the “discharge power supply” of the present invention. In addition, ball grid 1
2b corresponds to the "non-opposing portion" of the present invention.

The current detector 90 measures a current flowing through the conductive path and outputs an analog signal corresponding to the measured current. After this analog signal is converted into a digital signal by the A / D converter 91, the control unit 3
0 is given.

Here, as shown in FIG. 1, for example, only the right end switch portion 421 of the plurality of switch portions constituting the multiplexer 42 is connected to the other terminal side and the probe 411 connected to this switch portion 421 Consider the case where only the voltage (V1 + V2) is applied. In this case, the wiring 121 corresponds to the “wiring to be inspected” of the present invention, and if the wiring 121 is in a normal conduction state, a discharge region sandwiched between the wiring 121 and the discharge electrode 53 (in FIG. A discharge occurs in the region (DR) DR, and a current flows along the above-described conductive path. On the other hand, when the wiring 121 is in a non-conductive state, no discharge occurs in the discharge region DR, and no current flows. Therefore, the control unit 30 can detect the occurrence of discharge based on the current measured by the current detection unit 90 and determine the conduction / non-conduction state of the wiring 121 to be inspected. As described above, in this embodiment, the current detection unit 90 functions as the “discharge occurrence detection unit” of the present invention, and the control unit 30 functions as the “determination unit” of the present invention.

In this embodiment, the wiring 1 to be inspected is
During the inspection of the conduction / non-conduction state of the switch 21, the switch unit 42
1 are connected to one terminal side, and a voltage V1 is applied to the wirings 12 other than the wiring 121 to be inspected. Therefore, discharge can be reliably generated only between the inspection target wiring 121 and the discharge electrode 53, and the measurement accuracy is improved. When the disconnection inspection of the inspection target wiring 121 is completed and the connection status at each switch unit is switched, the inspection target wiring is sequentially switched, and the disconnection inspection of each wiring can be performed. Thus, in this embodiment, the multiplexer 42 functions as the “selection unit” of the present invention.

When the output voltages of the first and second power supplies 81 and 82 are adjusted so that the voltage applied to the discharge electrode 53 is lower than the discharge start voltage, the occurrence of discharge in the discharge region DR is prevented. be able to. Then, by controlling the switching of the switch unit of the multiplexer 42 in the discharge prevention state, a short circuit test between the wirings can be performed. For example, as shown in FIG.
Switch unit 4 at the right end of the plurality of switch units
When only 21 is connected to the other terminal and the other switch is connected to one terminal, the wiring 121 connected to the switch 421 is selected as the reference wiring. Here, if another wiring is short-circuited with respect to the reference wiring 121, the current detection unit 90, the switch unit 421 of the multiplexer 42, the wiring 121, the short-circuited part, and the positive terminal of the second power supply 82. A conductive path is formed to reach the negative terminal of the second power supply 82 via another switch unit. Therefore, in this device, the short-circuit resistance Rx is obtained from the detection output (current value) I of the current detection unit 90 and the output voltage V2 of the second power supply 82 based on the following equation: Rx = V2 / I. It is possible to inspect whether or not the reference wiring 121 is short-circuited with another wiring based on. When the short-circuit inspection of the reference wiring 121 is completed and the connection status of each switch unit is switched, the reference wiring is sequentially switched, and the short-circuit inspection of each wiring is performed.

In this embodiment, the discharge voltage in the short-circuit inspection is prevented by setting the voltage applied to the discharge electrode 53 to be lower than the discharge start voltage.
An open / close switch may be separately provided between the power supply device 1 and the power supply device 1 so that both devices are in a conductive state during a disconnection test, and both are in a non-conductive state during a short circuit test. Also, the discharge region DR
By controlling the atmosphere, the discharge starting voltage may be increased during the short-circuit inspection to prevent the occurrence of discharge during the short-circuit inspection. In other words, any configuration may be adopted as long as the configuration and means can prevent the occurrence of discharge in the discharge region DR during the short circuit inspection.

Next, the third power supply 83 will be described. The plus output terminal of the third power supply 83 is connected to the pre-discharge electrode 54
The negative output terminal is connected to the discharge electrode 53 via the current detection unit 90. Then, the third power supply 8 in response to a preliminary discharge command from the control unit 30.
3 is temporarily raised to the voltage V3, the discharge electrode 53
And a preliminary discharge electrode 54 generates a preliminary discharge. This preliminary discharge is performed by the inspection target wiring and the discharge electrode 53 as described later.
And has a function of assisting the discharge between the two and is performed prior to the discharge. This preliminary discharge is not an essential requirement, but by performing the preliminary discharge, the discharge starting voltage V0 can be reduced, and in this regard, the preliminary discharge has an advantageous effect over the prior art in which the preliminary discharge is not performed. It can be said that.

FIG. 3 is a flowchart showing the operation of the circuit board inspection apparatus shown in FIG. In this inspection device,
Work holder 2 located at load / unload position
When the untested work (circuit board) 10 is loaded into the inspection device 1 by a handling device (not shown) arranged in parallel with the inspection device or a manual operation of an operator (step S1), the control unit 30 controls each unit of the device. Control and
The work 10 is inspected by executing the following steps S2 to S9.

First, in step S2, the work holder 21 clamps and holds the work 10. Then, while holding the work 10, the work holder 21 moves to the inspection position (the position shown in FIG. 1) for inspecting the work 10 (step S3). Thus, the work 10 is positioned at the inspection position.

Subsequently, the upper jig 50 and the lower jig 40 move toward the work 10, and the work 10 is sandwich-pressed (step S4). This work 1
By the movement of the lower jig 40 to zero, as shown in FIG. 1, the distal end of each conductive spring probe 41 is pressed against the corresponding ball grid 12 b of the wiring 12 to be electrically connected. On the other hand, when the upper jig 50 is moved to the work 10, the packing 52 is sandwiched between the flange portion of the chamber 51 and the outer peripheral edge of the work 10 as shown in FIG. A closed space SP surrounded by the recess 52 and the recess 51a of the chamber 51 is formed. In the closed space SP,
As the discharge electrode 53 covers all the pad portions 12a,
It is positioned facing away from the pad portion 12a by a predetermined distance. As a result, a discharge region DR is formed between the discharge electrode 53 and the pad portion 12a.

When the inspection preparation of the work 10 is completed, a disconnection inspection (step S5) and a short-circuit inspection (step S6) are executed to check the conduction state of the work 10. The details of these inspections will be described later.

When the inspection is completed, the lower jig 40 and the upper jig 50 are moved away from the work 10 to release the pressing of the work 10 (step S7), and then the work holder 21 is moved to the load / unload position. Move to work 1
The clamp of 0 is released (step S8). Finally, when it is confirmed in step S9 that the work 10 whose inspection has been completed has been carried out of the work holder 21, the flow returns to step S1 to execute the above series of processing.

Next, the disconnection inspection (step S5) will be described in detail below with reference to FIGS. FIG.
4 is a flowchart showing a disconnection inspection in the circuit board inspection apparatus according to the present invention. FIG. 5 is a timing chart in the disconnection inspection. In FIG. 5, “SCAN1”, “SCAN2”,... Indicate the disconnection inspection for the first and second wirings 12, respectively.

The closed space S formed in step S4
P is filled with air containing oxygen, and if a discharge is generated in this gas component state, a spark may be generated as described above, and the work 10 may be contaminated. Therefore, in this embodiment, first, the electromagnetic valve 62 is opened while the electromagnetic valve 61 is closed to allow the closed space SP to communicate with the exhaust unit 72, and then the exhaust unit 72 is operated to release the air in the closed space SP. Is exhausted (step S51). Thereafter, the solenoid valve 62
, The solenoid valve 61 is opened to allow the closed space SP to communicate with the rare gas supply unit 71, and then the rare gas supply unit 71 is opened.
Is operated to supply a rare gas to the closed space SP (step S52). As a result, the closed space S including the discharge region DR
The inside of P is filled with a rare gas, and the oxygen concentration is zero or extremely low. Further, by controlling the supply amount of the rare gas, the density of the rare gas component in the discharge region DR can be adjusted, and the discharge starting voltage can be controlled. Therefore,
It is also possible to obtain the relationship between the density of the rare gas component and the discharge starting voltage in advance, and control the supply amount of the rare gas so that the discharge starting voltage becomes the lowest.

Here, as the rare gas, an inert gas such as argon or neon can be used. A single type of inert gas may be used as the rare gas, or a plurality of types of inert gas may be used. A mixture of gases at an appropriate mixing ratio may be used. In this embodiment, a rare gas having a mixture ratio of 9: 1 to a partial pressure ratio of argon and neon is used in order to reduce the discharge starting voltage due to the paying effect.

Each of the power supplies 81 to 83 is shown in FIG.
As shown in the figure, after the first power supply 81 is boosted from zero to the voltage V1 at a predetermined timing, the third power supply 83 is temporarily boosted to the voltage V3 prior to the disconnection inspection of each wiring 12 (step S53). ). Thereby, the discharge electrode 53
A preliminary discharge is generated between the electrode and the preliminary discharge electrode 54, so that the discharge in the discharge region DR is facilitated and the discharge starting voltage can be reduced. Of course, during the pre-discharge,
Since the output voltage of the second power supply 82 is set to zero,
The potential applied to each wiring 12 is a potential V1 lower than the discharge start voltage V0, and no discharge occurs in the discharge region DR.

When the preliminary discharge is completed, the multiplexer 42 operates in response to the selection command from the control unit 30, and the first
Only the second wiring 12 is electrically connected to the plus output terminal of the second power supply 82. When the first inspection target wiring is selected in this way, “SCAN1” in FIG. 5 is executed.
That is, the second power supply 82 is temporarily boosted to the voltage V2, and the ball grid 12b of the inspection target wiring 12
A potential difference (V1 + V2) higher than the discharge start voltage V0 is applied to the discharge electrode 53 (step S54). Therefore, when a part of the inspection target wiring 12 is disconnected, no discharge occurs in the discharge region DR, whereas when no disconnection exists, a discharge occurs in the discharge region DR.

Therefore, in this embodiment, step S5
5, it is determined whether or not a predetermined time ΔT has elapsed immediately after the output from the second power supply 82 has been boosted, and the detection output (current value) of the current detection unit 90 at the time point is measured (step S56). . Then, it is determined whether or not the selected wiring is disconnected based on the current value (step S57). Then, the wiring to be inspected is selected (step S
A series of processing from 54) to disconnection determination (step S57) is repeatedly executed until it is determined in step S58 that inspection has been completed for all wirings. Therefore, for example, “SCAN1” and “SCAN2” shown in FIG.
In "SCAN4" and "SCAN4", a current associated with the occurrence of discharge is detected, and no disconnection is observed in the first, second, and fourth wirings, indicating that the conduction state is good. On the other hand, in “SCAN3”, the current associated with the occurrence of discharge is not detected, so that the third wiring is disconnected.
Understand.

As described above, the inspection apparatus according to this embodiment is common to the prior art in that the disconnection of the wiring is inspected by utilizing the discharge phenomenon, but the discharge region DR is set in a rare gas atmosphere. Therefore, even if a discharge phenomenon occurs, the discharge region DR
Thus, no sparks are generated at this time, and the contamination of the work 10 can be reliably prevented.

Further, in this embodiment, the closed space SP is formed by surrounding the discharge region DR, the discharge electrode 53 and the preliminary discharge electrode 54 by the chamber 51.
Is configured to supply the rare gas from the rare gas supply unit 71, the following operation and effect can be obtained. That is, the atmosphere of the discharge region DR can be separated from the peripheral region containing oxygen, and the inflow of oxygen from the peripheral region to the discharge region DR can be reliably prevented. Also, the closed space S
By forming P, the discharge area D by the exhaust unit 72
Air from R can be reliably removed, and the oxygen concentration in discharge region DR can be reliably reduced. In addition, the supply amount of the rare gas can be suppressed, and the running cost can be reduced.

Further, by applying a potential difference V3 between the preliminary discharge electrode 54 and the discharge electrode 53 disposed in the closed space SP, a preliminary discharge is generated in the closed space SP to lower the discharge starting voltage. Therefore, the potential difference to be applied between the ball grid 12b corresponding to the non-opposing portion of the present invention and the discharge electrode 53 can be set low, and damage to the work (circuit board) 10 due to discharge can be suppressed. .

Further, in the above-described embodiment, while the potential difference (V1 + V2) is applied between the inspection target wiring and the discharge electrode 53, the discharge starting voltage V0 is applied between the wiring other than the inspection target wiring and the discharge electrode 53. Since a lower potential difference V1 is applied, a discharge between the wiring that is not an inspection target and the discharge electrode 53, that is, an erroneous discharge can be reliably prevented. It is not an essential requirement that the voltage V1 be applied to the wiring when the wiring is not an inspection target. In this sense, the first power supply 81 functioning as a power supply for preventing erroneous discharge can be said to be an optional component.

Next, the short-circuit test (step S6) will be described with reference to FIG. FIG. 6 is a flowchart showing a short circuit inspection in the circuit board inspection apparatus according to the present invention. In this short-circuit inspection, first, the electromagnetic valve 62 is opened to make the closed space SP communicate with the exhaust unit 72, and then the exhaust unit 72 is operated. Thus, the discharge gas generated in the closed space SP in the disconnection inspection (step S5) is exhausted from the closed space SP (step S61).

The multiplexer 42 operates in response to a selection command from the control unit 30, and one of a plurality of wirings is operated.
This wiring is selected as a reference wiring (step S6).
2). For example, as shown in FIG. 1, when the wiring 121 connected to the switch unit 421 is selected as a reference wiring,
The reference wiring 121 is connected to the positive terminal of the second power supply 82. Other wiring is the second power supply 8
2 negative terminal.

Following the selection of the reference wiring, the current value I is measured by the current detecting section 90, and the detection result is given to the control section 30 (step S63). Then, the control unit 30 obtains the short-circuit resistance Rx based on the following equation: Rx = V2 / I, and determines whether the reference wiring 121 is short-circuited with another wiring based on the short-circuit resistance Rx (step S64).

The selection of the reference wiring (step S62)
The series of processes from the determination to the short-circuit determination for the reference wiring (step S64) are repeatedly performed until all the wirings are selected as the reference wiring in step S65 and it is determined that the inspection has been completed for all the wirings.

The present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention. For example, the inspection apparatus according to the above-described embodiment performs “disconnection inspection” and “short-circuit inspection” in this order as the inspection of the conductive state of the work (circuit board) 10.
The inspection order is not limited to this. Further, the application target of the present invention is not limited to this, and the present invention can be applied to at least an inspection apparatus that performs “disconnection inspection”.

In the above embodiment, the circuit board 10 on which the semiconductor chip can be mounted in the C4 system is to be inspected, but the circuit board that can be inspected by the present invention is not limited to this. . For example, the present invention can be applied to a circuit board having wiring formed only on one surface of a base substrate, a circuit board having a folded wiring pattern, and the like.

Further, the discharge electrode 53 is not limited to a flat electrode, but may be formed of a flat metal plate to a pad portion 1.
An electrode provided with one or a plurality of protrusions toward 2a can be used, or a block-shaped or conical electrode can be used. Also, the preliminary discharge electrode 54 is not limited to the flat electrode, and may have any shape and size.

In the above embodiment, the current detecting section 90
The discharge occurrence in the discharge region DR is detected on the basis of the current value detected by the above, and functions as the “discharge occurrence detecting means” of the present invention. However, the discharge occurrence detecting means is not limited to this. Absent.

In the above embodiment, each of the "SACA"
N), a pulsed DC discharge voltage equal to or higher than the discharge start voltage is applied between the inspection target wiring and the discharge electrode 53 only once, but the number of pulses is not limited to one. You may make it apply several times. Alternatively, while the DC voltages of the output voltages V1 and V2 are continuously output from the power supplies 81 and 82, the wirings to be inspected may be switched by the multiplexer 42 to inspect the conductive state of each wiring. Further, an AC voltage may be used instead of the DC voltage.

Further, in the above embodiment, the chamber 51
The atmosphere in the discharge region DR is controlled by supplying a rare gas to the closed space SP formed by the
The formation of the closed space SP by 1 is not an essential component, and for example, a rare gas from the rare gas supply unit 71 may be supplied directly to the discharge region DR to replace the discharge region DR with a rare gas atmosphere.

[0058]

As described above, according to the present invention, after a rare gas is supplied to a discharge region and replaced with a rare gas atmosphere, a non-facing portion of the wiring to be inspected, which does not face the discharge electrode, Since a potential difference equal to or higher than the discharge starting voltage is applied between the discharge electrode and the discharge electrode, the continuity of the inspection target wiring is inspected based on the occurrence of discharge in the discharge region. This can reliably prevent the occurrence of sparks, and can prevent contamination of the circuit board due to spark generation.

Further, according to the present invention, a preliminary discharge electrode arranged in a closed space and a preliminary discharge power supply for generating a preliminary discharge in the closed space by giving a potential difference between the discharge electrode and the discharge electrode. Further, since a preliminary discharge is provided, a preliminary discharge can be generated in a closed space including a discharge region to lower a discharge starting voltage. As a result, the potential difference to be applied between the non-facing portion and the discharge electrode can be set low, and damage to the circuit board due to discharge can be suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a circuit board inspection apparatus according to the present invention.

FIG. 2 is a block diagram showing an electrical configuration of the inspection device of FIG.

FIG. 3 is a flowchart showing an operation of the circuit board inspection apparatus shown in FIG. 1;

FIG. 4 is a flowchart showing a disconnection inspection in the circuit board inspection apparatus according to the present invention.

FIG. 5 is a timing chart in a disconnection inspection.

FIG. 6 is a flowchart showing a short circuit inspection in the circuit board inspection apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Work (circuit board) 12, 121 ... Wiring 12a ... Pad part 12b ... Ball grid (non-opposing part) 12c ... Conductive part 30 ... Control part (determination means) 42 ... Multiplexer (selection means) 51 ... Chamber 53 ... Discharge electrode 54 Preliminary discharge electrode 71 Noble gas supply unit 72 Exhaust unit 81 First power supply (power supply for preventing erroneous discharge; discharge power supply) 82 Second power supply (power supply for discharge) 83 Third power supply (standby) Power supply for discharge) 90 ... Current detection unit (discharge occurrence detection means) DR ... Discharge area SP ... Closed space

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayuki Nakahara 126 Makishima-cho, Makishima-cho, Uji-city, Kyoto Inside Nidec-Lead Co., Ltd. 2G014 AA02 AA03 AA13 AB20 AB21 AB59 AC09 AC10

Claims (12)

[Claims] 1. An inspection apparatus for inspecting a plurality of wirings formed on a circuit board, comprising: a discharge electrode which is spaced apart from a part of a wiring to be inspected among the plurality of wirings; A non-facing portion of the wiring that does not face the discharge electrode; a discharge power supply that provides a potential difference equal to or greater than a discharge starting voltage between the discharge electrode; and a discharge sandwiched between the discharge electrode and the inspection target wiring. Discharge occurrence detection means for detecting occurrence of discharge in a region, rare gas supply means for supplying a rare gas to the discharge region, and determination of determining a conduction state of the inspection target wiring based on a detection result by the discharge occurrence detection means And a means for inspecting a circuit board. 2. The apparatus according to claim 1, further comprising a chamber surrounding the discharge region and the discharge electrode to form a closed space, wherein the rare gas supply unit communicates with the chamber to supply a rare gas into the closed space. 2. The circuit board inspection apparatus according to claim 1. 3. A rare gas supply means for supplying a rare gas to the closed space by the rare gas supply means, further comprising an exhaust means connected to the chamber and exhausting a gas component present in the closed space to the outside of the chamber. 3. The circuit board inspection apparatus according to claim 2, wherein the exhaust means exhausts a gas component in the closed space out of the chamber before the exhaust. 4. A pre-discharge power source for generating a pre-discharge in the closed space by applying a potential difference between the pre-discharge electrode disposed in the closed space, and the pre-discharge electrode and the discharge electrode. The circuit board inspection apparatus according to claim 2, further comprising: 5. The erroneous discharge prevention power supply for providing a potential difference lower than a discharge start voltage between a wiring other than the wiring to be inspected among the plurality of wirings and the discharge electrode. An inspection device for a circuit board according to any one of the above. 6. An erroneous discharge prevention power supply for generating a voltage lower than a discharge start voltage, and one of the plurality of wirings is selected as a wiring to be inspected, and the wiring to be inspected is electrically connected to the power supply for discharging. Selecting means for electrically connecting a wiring other than the wiring to be inspected among the plurality of wirings to the power source for preventing erroneous discharge, and sequentially switching the wiring to be inspected, 5. The circuit board inspection apparatus according to claim 1, wherein each time the inspection target wiring is switched by the selection unit, the conduction state of the inspection target wiring is determined. 7. The circuit board inspection apparatus according to claim 1, wherein the discharge electrodes are spaced apart from each other for a part of each of the wirings. 8. The circuit board inspection apparatus according to claim 7, wherein said discharge electrode is a plate-like electrode, and is disposed substantially parallel to said circuit board. 9. The discharge electrode includes a plate-like electrode portion disposed substantially parallel to the circuit board, and a plurality of projecting electrode portions projecting from the plate-like electrode portion toward the circuit board. The circuit board inspection apparatus according to claim 7, comprising: 10. An inspection method for inspecting a plurality of wirings formed on a circuit board, wherein the discharging of the circuit board is performed such that a discharge electrode faces a part of a wiring to be inspected among the plurality of wirings. A first step of disposing the discharge region between the discharge electrode and the inspection target wiring with a rare gas atmosphere after the first step;
A step, after the discharge region is replaced with a rare gas atmosphere, a non-facing portion of the wiring under test that does not face the discharge electrode;
A third step of providing a potential difference equal to or greater than a discharge start voltage between the discharge electrode and the discharge electrode, and detecting a discharge occurrence in a discharge region sandwiched between the discharge electrode and the inspection target wiring; A fourth step of determining a conduction state of the wiring to be inspected. 11. A fifth step of exhausting a gas component present in the discharge region after the fourth step, and after the fifth step, one of the plurality of wirings is selected as a reference wiring. The circuit board inspection method according to claim 10, further comprising: a sixth step of giving a potential difference between the reference wiring and the other wiring to determine whether the reference wiring is short-circuited. 12. The circuit board inspection method according to claim 11, wherein in the sixth step, each time the determination of the short circuit is completed, the reference wiring is sequentially switched.