JP7444071B2 - Inspection device, inspection method, and program for inspection device - Google Patents

Description

The present invention relates to an inspection device, an inspection method, and a program for the inspection device for inspecting conductive paths.

Conventionally, a circuit board that measures the resistance value of the test object from the current value and voltage value by passing a measurement current through the wiring etc. of the test object provided on a circuit board and measuring the voltage generated in the test object. Inspection devices are known (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2012-117991

By the way, there are cases where a circuit board with components mounted on the board, a component-embedded board with components built into the board, a semiconductor substrate with a circuit formed thereon, etc. are inspected. In such a case, a diode or a plurality of current paths that produce diode characteristics similar to those of a diode may be connected in parallel.

For example, if two regular conductor patterns are connected in parallel and the resistance value of this parallel circuit is measured using the board inspection device described above, if one of the two wires breaks, the resistance value will double. . Therefore, if one of the two conductor patterns connected in parallel is disconnected, the disconnection can be detected based on the resistance value.

However, diodes have a non-linear relationship between current and voltage, and even if one of the two diodes connected in parallel is disconnected, the voltage generated for the current flowing to measure resistance will be Almost no change.

Therefore, when a plurality of diodes are connected in parallel and the circuit board is inspected using the above-mentioned board inspection apparatus, even if some of the diodes are disconnected, it is difficult to detect the disconnection, which is a problem.

An object of the present invention is to provide an inspection apparatus, an inspection method, and a program for an inspection apparatus, which facilitate inspection of an inspection object in which a plurality of diodes are connected in parallel.

The inspection device according to an example of the present invention has a diode characteristic in which a change in current with respect to a change in voltage when a forward voltage exceeds an on-voltage is larger than when the forward voltage is less than the on-voltage. This is an inspection device for inspecting a part to be inspected in which a plurality of current paths are connected in parallel, and includes a current supply part capable of supplying current, a voltage measurement part capable of measuring voltage, and a preset a measurement processing unit that causes the current supply unit to flow a current having a first current value between the two ends, and causes the voltage measurement unit to measure the voltage between the two ends as the first voltage value, and the first current value is less than or equal to a current value at which the voltage across the normal inspection target section substantially becomes the on-state voltage.

Further, in the inspection device according to an example of the present invention, when the forward voltage exceeds the on-voltage, a change in current with respect to a change in the voltage is larger than when the forward voltage is less than the on-voltage. This is an inspection device for inspecting a part to be inspected in which a plurality of current paths having diode characteristics are connected in parallel, and includes a voltage supply section that can output voltage, a current measurement section that can measure current, and substantially While applying a voltage of a first voltage value preset below the on-voltage between both ends of the inspection target part by the voltage supply part, the current flowing between the ends is measured by the current measurement part to a first current value. and a measurement processing unit that performs measurement.

Further, in the inspection method according to an example of the present invention, a change in current with respect to a change in voltage when the forward voltage exceeds the on-voltage is larger than when the forward voltage is less than the on-voltage. An inspection method for inspecting a part to be inspected in which a plurality of current paths having diode characteristics are connected in parallel, the method comprising: flowing a current of a preset first current value between the two ends, and increasing the voltage between the two ends; The method includes a measurement processing step of measuring as a first voltage value, and the first current value is less than or equal to a current value at which the voltage across the normal inspection target portion becomes substantially the on-voltage.

Further, in the inspection method according to an example of the present invention, a change in current with respect to a change in voltage when the forward voltage exceeds the on-voltage is larger than when the forward voltage is less than the on-voltage. An inspection method for inspecting a part to be inspected in which a plurality of current paths having diode characteristics are connected in parallel, the method comprising: applying a voltage of a first voltage value preset substantially below the on-voltage to the part to be inspected; The method includes a measurement processing step of applying a current between both ends and measuring a current flowing between the both ends as a first current value.

Further, in the inspection device according to an example of the present invention, when the forward voltage exceeds the on-voltage, a change in current with respect to a change in the voltage is larger than when the forward voltage is less than the on-voltage. An inspection device for inspecting a part to be inspected in which a plurality of current paths having diode characteristics are connected in parallel, wherein one of current or voltage is applied to both ends of the part to be inspected multiple times with different values. the other of the current or voltage between the two ends is measured during each period in which the one is supplied, and the current that turns on the inspected part based on the measured change in the other; and a determination unit that determines the quality of the part to be inspected based on the current acquired by the measurement processing unit.

Further, in the inspection method according to an example of the present invention, a change in current with respect to a change in voltage when the forward voltage exceeds the on-voltage is larger than when the forward voltage is less than the on-voltage. An inspection method for inspecting a part to be inspected in which a plurality of current paths having diode characteristics are connected in parallel, the method comprising: applying one of current or voltage to both ends of the part to be inspected multiple times with different values; the other of the current or voltage between the two ends is measured during each period in which the one is supplied, and the current that turns on the inspected part based on the measured change in the other; and a determination step of determining whether the inspection target part is good or bad based on the current acquired by the measurement processing section.

Further, an inspection device program according to an example of the present invention is an inspection device program for operating the above-mentioned inspection device, and causes a computer to function as the measurement processing section.

1 is a block diagram showing an example of the configuration of an inspection device that uses an inspection method according to an embodiment of the present invention. It is a conceptual diagram which shows another example of a part to be inspected. 7 is a graph showing an example of current-voltage characteristics when a current is passed in a forward direction through a portion to be inspected. 2 is a flowchart showing an example of the operation of the on-voltage search section shown in FIG. 1. FIG. 2 is a flowchart showing an example of the operation of the on-voltage search section shown in FIG. 1. FIG. It is an explanatory diagram showing an example of measurement information. FIG. 2 is an explanatory diagram showing an example of a slope and a ratio. 2 is a flowchart showing an example of an inspection method by the measurement processing section and determination section shown in FIG. 1. FIG. 3 is a graph showing an example of current-voltage characteristics when a current is passed in the forward direction through a portion to be inspected in which three current paths are connected in parallel. 2 is a block diagram showing another example of the inspection device shown in FIG. 1. FIG. It is a block diagram showing an example of composition of an inspection device concerning a second embodiment. 12 is a flowchart illustrating an example of the operation of the reference slope acquisition unit illustrated in FIG. 11. FIG. 12 is an explanatory diagram for explaining operations of a reference slope acquisition section, a measurement processing section, and a determination section shown in FIG. 11; 12 is a flowchart illustrating an example of the operation of the measurement processing section and determination section illustrated in FIG. 11. FIG. 12 is an explanatory diagram for explaining operations of a reference slope acquisition section, a measurement processing section, and a determination section shown in FIG. 11; It is a flow chart which shows an example of operation of a measurement processing part and a judgment part concerning a third embodiment. It is a flow chart which shows an example of operation of a measurement processing part and a judgment part concerning a third embodiment. It is an explanatory diagram for explaining operation of a measurement processing part and a judgment part concerning a third embodiment. It is a flowchart which shows the modification of the operation of the measurement processing part and judgment part concerning a third embodiment. It is an explanatory diagram for explaining operation of a measurement processing part and a judgment part concerning a third embodiment.

Hereinafter, embodiments according to the present invention will be described based on the drawings. It should be noted that structures given the same reference numerals in each figure indicate the same structure, and the explanation thereof will be omitted.
(First embodiment)

The inspection device 1 shown in FIG. 1 includes a current supply section 2, a voltage measurement section 3, a current measurement section 4, probes Pr1, Pr2, and a control section 5. The inspection apparatus 1 may be a substrate inspection apparatus that inspects a substrate, or may be a semiconductor inspection apparatus that inspects a semiconductor wafer or the like. FIG. 1 shows a state in which probes Pr1 and Pr2 of the inspection apparatus 1 are brought into contact with a circuit board 100 to be inspected.

The circuit board 100 includes, for example, a wiring board 101 and a component 102 mounted on the surface of the wiring board 101. The wiring board 101 is a so-called printed wiring board. On the surface of the wiring board 101, wiring patterns W1 to W8 are formed.

The wiring board 101 is, for example, a printed wiring board, a film carrier, a flexible board, a ceramic multilayer wiring board, a semiconductor substrate such as a semiconductor chip and a semiconductor wafer, a package board for a semiconductor package, an electrode plate for a liquid crystal display or a plasma display, and the like. It may also be an intermediate substrate in the process of manufacturing a substrate, or a so-called carrier substrate. Further, the circuit board 100 may be, for example, a component-embedded board, or may be, for example, a semiconductor substrate on which circuit elements are formed by a semiconductor process. The inspection target of the inspection apparatus 1 may be a substrate, a semiconductor wafer, a semiconductor element, or the like. The wiring board 101 is provided with an inspection target portion A to be inspected.

Component 102 includes diodes D1 and D2 and terminals T1 to T4. The anode of the diode D1 is connected to the terminal T1, and the cathode is connected to the terminal T2. The anode of diode D2 is connected to terminal T3, and the cathode is connected to terminal T4. The diodes D1 and D2 may be, for example, protection diodes built into a semiconductor integrated circuit (IC).

The component 102 may be various components such as a semiconductor integrated circuit, a semiconductor element, a diode element, a diode array, and an LED (Light Emitting Diode). A diode has a characteristic that when the voltage applied in the forward direction is gradually increased, the current flowing at a certain voltage increases rapidly. The voltage at which this current rapidly increases is called the on-voltage.

The component 102 only needs to have nonlinear characteristics (hereinafter referred to as diode characteristics) in which the current that flows increases rapidly when a voltage exceeding the on-state voltage is applied, similar to a diode, and is not necessarily a diode itself. You don't have to. Although FIG. 1 shows an example in which the single component 102 includes two diodes D1 and D2, the diodes D1 and D2 may be separate components. For example, the diode D1 and the diode D2 may be included in separate ICs or the like, and may be connected in parallel by external wiring. Further, the number of diodes may be three or more.

Furthermore, the diodes D1 and D2 are not limited to those intentionally formed as diode elements. The diodes D1 and D2 may be protection diodes of semiconductor elements, parasitic diodes, etc., or may have diode characteristics due to an oxide film at the junction of wiring or the junction of different materials, and the diodes D1 and D2 may be used as parts of the wiring board 101. It is not limited to cases where it can be attached to.

Pads Pa1 to Pa4 are formed at one ends of the wiring patterns W1 to W4. Pad Pa1 is connected to terminal T1, pad Pa2 to terminal T2, pad Pa3 to terminal T3, and pad Pa4 to terminal T4. The other end of the wiring pattern W1 and the other end of the wiring pattern W3 are connected by a wiring pattern W5, and the other end of the wiring pattern W2 and the other end of the wiring pattern W4 are connected by a wiring pattern W6. A wiring pattern W7 extends from the wiring pattern W5, and a pad Pa5 is provided at the tip of the wiring pattern W7. A wiring pattern W8 extends from the wiring pattern W6, and a pad Pa6 is provided at the tip of the wiring pattern W8.

As a result, a current path A1 is formed in which the wiring pattern W1, the diode D1, and the wiring pattern W2 are connected in series, and a current path A2 is formed in which the wiring pattern W3, the diode D2, and the wiring pattern W4 are connected in series. . Current paths A1 and A2 correspond to an example of a current path having diode characteristics. Current paths A1 and A2 are connected in parallel by wiring patterns W5 and W6.

The circuit portion from pad Pa5 to pad Pa6 is designated as inspection target portion A. In this embodiment, the inspection target section A that is the inspection target of the inspection apparatus 1 is a circuit provided between pads Pa5 and pads Pa6. That is, one end of the portion A to be inspected is a pad Pa5, and the other end is a pad Pa6. Note that when the diodes D1 and D2 are built into the semiconductor integrated circuit, the diodes D1 and D2 may be connected in parallel within the semiconductor integrated circuit.

The probes Pr1 and Pr2 are moved by a moving mechanism (not shown) and are brought into contact with pads Pa5 and Pa6 set in advance as inspection points. Note that the inspection device 1 may be configured to include, for example, several hundred to several thousand probes held in a multi-needle configuration. Then, probes Pr1 and Pr2 are selected from among the multi-needle probes by a switching circuit (not shown), and the probes Pr1 and Pr2 are connected to the current supply section 2, the voltage measurement section 3, and the current measurement section 4. It may be a configuration. Further, the probes Pr1 and Pr2 may be so-called flying probes that can be moved in position arbitrarily.

FIG. 2 shows an example where two diodes built into the semiconductor integrated circuit 103 are connected in parallel within the semiconductor integrated circuit 103. In FIG. 2, a circuit around the input port is shown as a semiconductor integrated circuit 103 as an example of an input/output port. The semiconductor integrated circuit 103 includes an input buffer 104, protection diodes D3 to D6, a signal input terminal T5, a power terminal V+, and a power terminal V-.

The input terminal of the input buffer 104 is connected to the signal input terminal T5, the anodes of the protection diodes D3 and D4, and the cathodes of the protection diodes D5 and D6. The cathodes of the protection diodes D3 and D4 are connected to the power supply terminal V+, and the anodes of the protection diodes D5 and D6 are connected to the power supply terminal V-. The signal input terminal T5, power supply terminal V+, and power supply terminal V- are respectively connected to pads Pa7, Pa8, and Pa9 provided on, for example, an IC socket or a board.

When the circuit section from pad Pa7 to pad Pa8 is defined as the inspection target section B, the inspection apparatus 1 may be operated by contacting the probe Pr1 with the pad Pa7 and the probe Pr2 with the pad Pa8. When the circuit section from pad Pa9 to pad Pa7 is the inspection target section C, as shown in parentheses in FIG. Just make it work. Note that the probes Pr1 and Pr2 may be brought into direct contact with the signal input terminal T5 and the power supply terminals V+ and V-. The probes Pr1 and Pr2 do not need to be physically moved, and their connection relationship may be changed using a switching circuit or the like, as will be described later.

The current supply section 2 is configured using, for example, a constant current circuit. The positive electrode of the current supply section 2 is connected to the probe Pr1, and the negative electrode of the current supply section 2 is connected to the probe Pr2. Thereby, the current supply section 2 supplies forward current to the diodes D1 and D2 according to the control signal from the control section 5.

The voltage measuring section 3 is a so-called voltmeter, and is configured using, for example, an analog-to-digital converter, a voltage dividing circuit, and the like. The voltage measurement section 3 measures the voltage between the probes Pr1 and Pr2, that is, the voltage across the inspection target part A that the probes Pr1 and Pr2 come into contact with, and outputs a signal indicating the measured voltage to the control section 5.

The current measuring section 4 is a so-called ammeter, and is configured using, for example, an analog-to-digital converter, a shunt resistor, a Hall element, and the like. The current measurement unit 4 measures the current flowing between the probes Pr1 and Pr2, that is, the current flowing in the inspection target part A that the probes Pr1 and Pr2 come into contact with, and outputs a signal indicating the measured current to the control unit 5.

The control unit 5 is a so-called microcomputer, and includes, for example, a CPU (Central Processing Unit) that executes predetermined arithmetic processing, a RAM (Random Access Memory) that temporarily stores data, a nonvolatile flash memory, and an HDD (Hard Drive). The storage unit 54 includes a storage unit 54 including a disk drive, etc., and peripheral circuits thereof. The storage unit 54 stores in advance an inspection device program according to an embodiment of the present invention. The control unit 5 functions as a measurement processing unit 51, a determination unit 52, and an on-voltage search unit 53 by executing the inspection device program stored in the storage unit 54.

The measurement processing unit 51 causes the current supply unit 2 to cause a current having a first current value Ia set in advance to flow between the probes Pr1 and Pr2, and the voltage measurement unit 3 to increase the voltage between the probes Pr1 and Pr2 to a first value. Measure it as a voltage value Va. The first current value Ia is set in advance to be less than or equal to a reference current value IS, which is a current value at which the voltage across the normal inspection target part A becomes substantially an on-voltage. The measurement processing unit 51 controls the current supply unit 2 so that the current value measured by the current measurement unit 4 is equal to the first current value Ia, so that the current of the first current value Ia is supplied from the current supply unit 2. You may also output it.

Note that the current value that substantially becomes the on-voltage is intended to allow for measurement errors and variations in degree. The first current value Ia may be, for example, a value within a range of approximately −10% to +10% with respect to the current value that accurately provides the on-voltage.

The determining unit 52 determines whether the inspection target part A is good or bad based on the first voltage value Va measured by the voltage measuring unit 3.

The on-voltage search unit 53 searches for the on-voltage Von of the part to be inspected A from a reference sample of the circuit board 100 that is different from the circuit board 100 to be inspected. The on-voltage Von of the reference sample is used to determine the determination standard of the determination unit 52 and the first current value Ia.

The on-voltage search unit 53 causes the current supply unit 2 to cause current to flow between the probes Pr1 and Pr2 multiple times while changing the current value. Then, the on-voltage search unit 53 causes the voltage measurement unit 3 to measure the voltage between the probes Pr1 and Pr2 during each period in which each current flows, and based on the changes in the plurality of measured voltages, the on-voltage search unit 53 causes the voltage measurement unit 3 to measure the voltage between the probes Pr1 and Pr2. Search for on-voltage Von.

Next, the operation of the inspection apparatus 1 configured as described above will be explained with reference to FIGS. 3 to 5. A graph G1 shown in FIG. 3 shows a graph when the inspection target part A is normal, and a graph G2 shows a graph when one of the current paths A1 and A2 is disconnected. Hereinafter, it is assumed that the characteristics of the diode D1 and the diode D2 are substantially equal. Note that the current-voltage characteristics of the inspection target part A shown in FIG. 3 and described later are merely examples, and the present invention is not limited thereto.

Note that in the flowcharts below, the same operations are given the same step numbers and their explanations will be omitted.

First, for example, a user places a normal circuit board as a reference sample on a mounting table (not shown). Then, the on-voltage search unit 53 brings the probe Pr1 into contact with the pad Pa5, and brings the probe Pr2 into contact with the pad Pa6 (step S1).

Next, the on-voltage search unit 53 assigns 1 to the variable k, and sets the current value I(k) to an initial value of, for example, 0.1 mA (step S2). The variable k is a serial number for associating the current value I and the voltage value V, where the current value I(k) indicates the k-th current value I, and the voltage value V(k) indicates the k-th voltage value V. , current value I and voltage value V having the same number correspond. Although the units for the current value I and the voltage value V may be omitted, the unit for the current value I is milliampere (mA), and the unit for the voltage value V is volt (V).

Next, the on-voltage search unit 53 causes the current supply unit 2 to cause a current with a current value I(k) to flow between the probes Pr1 and Pr2, and during the period when the current is flowing, the voltage measurement unit 3 causes the probe The voltage between Pr1 and Pr2 is measured as a voltage value V(k) (step S3).

Hereinafter, when the measurement processing section 51, the judgment section 52, the on-voltage search section 53, etc. cause the current supply section 2 to supply current, it is simply explained that the measurement processing section 51, the judgment section 52, the on-voltage search section 53, etc. When the measurement processing unit 51, the determination unit 52, the on-voltage search unit 53, etc. causes the voltage measurement unit 3 to measure the voltage, it is simply stated that the measurement processing unit 51, the determination unit 52, the on-voltage search unit 53, etc. It is stated that the search unit 53 or the like measures the voltage, and it is simply stated that the measurement processing unit 51, the determination unit 52, or the on-voltage search unit 53 or the like causes the current measurement unit 4 to measure the current. It is described that the section 52, the on-voltage search section 53, or the like measures the current.

Thereby, the on-voltage search unit 53 adjusts the voltage between the pads Pa5 and Pa6 to the voltage value V(k ). The on-voltage search unit 53 associates the thus measured voltage value V(k) with the number k and the current value I(k), and stores the voltage value V(k) in the storage unit 54 as measurement information.

FIG. 6 shows measurement information measured in step S3 and step S5, which will be described later. If a normal inspection target part A in which neither of the current paths A1 and A2 are disconnected has the characteristics shown in the graph G1, 0.033V is measured for a current of 0.1 mA.

Next, the on-voltage search unit 53 adds 1 to the variable k. Further, the on-voltage search unit 53 adds 0.1 to the current value I(k-1), that is, the previously set current value, to obtain a new current value I(k) (step S4). Thereby, the voltage value can be measured while increasing the current value by 0.1 mA. The smaller the amount of increase in the current value, the more accurate the on-voltage acquisition becomes, but the processing time increases. Therefore, the amount of increase in the current value is not limited to 0.1 mA, and may be set as appropriate depending on the balance between accuracy and processing time.

Next, in the same manner as in step S3, the on-voltage search unit 53 causes a current of current value I(k) to flow between the probes Pr1 and Pr2, and during the period in which the current is flowing, the voltage between the probes Pr1 and Pr2 is measured as a voltage value V(k) (step S5). The on-voltage search unit 53 associates the thus measured voltage value V(k) with the number k and the current value I(k), and stores the voltage value V(k) in the storage unit 54 as measurement information.

Now, since the current value I(k) is 0.2 mA, according to the graph G1, 0.065 V is measured for a current of 0.2 mA.

Next, the on-voltage search unit 53 calculates the slope r(k-1) based on the following equation (1) (step S6).

Slope r(k-1) = {I(k)-I(k-1)}/{V(k)-V(k-1)} ...(1)

Now, since k=2, I(2)=0.2, I(1)=0.1, V(2)=0.065, and V(1)=0.033, the slope r(1) = {I(2)-I(1)}/{V(2)-V(1)}=(0.2-0.1)/(0.065-0.033)=3.13 .

The on-voltage search unit 53 stores the slope r(k−1) obtained in this manner in the storage unit 54 as slope information.

Next, the on-voltage search unit 53 compares the current value I(k) with 1.0 mA (step S7). If the current value I(k) is less than 1.0 mA (NO in step S7), steps S4 to S7 are repeated again.

On the other hand, if the current value I(k) is 1.0 mA or more (YES in step S7), the on-voltage search unit 53 sets k-1 to the number of data n, which is the number of slope r (step S8), and steps The process moves to S11. The current value to be compared with the current value I(k) is not limited to 1.0 mA as long as it is set to a value larger than the current value at which the on-voltage is assumed to be obtained.

As described above, through the processes of steps S1 to S7, a current is passed between both ends of the inspection target part A multiple times with different current values, and the voltage between both ends of the inspection target part A is increased during each period in which each current flows. will be measured.

FIG. 7 is an explanatory diagram of the slope r calculated by the on-voltage search unit 53 shown in FIG. 1 and the ratio R described later. Now, since the number of data n is 9, slopes r(1) to r(9) corresponding to k=1 to 9 are stored in the storage unit 54.

As described above, through the processing of steps S2 to S7, the on-voltage search unit 53 causes the current to flow between the probes Pr1 and Pr2 multiple times while changing the current value, and during each period in which each current flows, the on-voltage search unit 53 Measure voltage.

Next, in step S11, the on-voltage search unit 53 assigns 2 to variable k (step S11).

Next, the on-voltage search unit 53 calculates the ratio R(k) based on the following equation (2) (step S12), and if k is less than n (NO in step S13), set the variable k to 1. After adding (step S14), steps S12 and S13 are repeated, and if k becomes n (YES in step S13), the process moves to step S15. As a result, ratios R(2) to R(n) corresponding to numbers 2 to n are calculated.

Ratio R(k)=r(k)/r(k-1)...(2)

In step S15, the on-voltage search unit 53 searches for the maximum R(m) among the ratios R(2) to R(n) as the ratio R corresponding to the on-voltage Von (step S15). The on-voltage search unit 53 acquires the number m from the maximum ratio R(m) searched for. Since the number m is the number of the voltage value V(m) corresponding to the on-voltage Von, searching for the maximum ratio R(m) is nothing but searching for the on-voltage Von.

In the example of FIG. 7, the maximum value is R(8)=4.2. Therefore, the number m=8.

Next, the on-voltage search unit 53 refers to the measurement information stored in the storage unit 54 in step S5, and stores V(m) as the on-voltage Von in the storage unit 54 (step S16). In the example shown in FIG. 6, the voltage value V(8) of number 8, which is equal to m, is 0.30V, so the on-voltage Von is 0.30V. The on-voltage Von is a voltage at which the flowing current increases rapidly when the voltage applied to the inspection target part A in the forward direction is gradually increased.

Further, the on-voltage search unit 53 calculates a first current value Ia based on the following equation (3), and stores it in the storage unit 54 (step S17). The first current value Ia is an on-current that turns on the inspected part A in which one of the plurality of current paths A1 and A2 is disconnected.

First current value Ia = I (m) x (Q-1)/Q (3)
However, Q is the number of parallel current paths having diode characteristics.

Now, the number of parallel parts of the part A to be inspected is 2, and in the example shown in FIG. 6, the current value I(8) of 8 whose number is equal to m is 0.8 mA. Ia=0.8/2=0.4mA.

Here, I(m) is approximately equal to the reference current value IS. Therefore, it is preferable that the on-voltage search unit 53 stores I(m) in the storage unit 54 as the reference current value IS in step S17.

Note that the first current value Ia only needs to be substantially equal to the on-current that turns on the inspected part A in which one of the plurality of current paths A1 and A2 is disconnected. The first current value Ia being substantially equal to the on-current means that, for example, an error in I(m) obtained in steps S1 to S17, an error in the voltage measurement unit between the first current value Ia and the on-current, 3 or the measurement error of the current measuring section 4, the output error of the current supply section 2, etc., are allowed. The first current value Ia may be, for example, a value within a range of about -10% to +10% with respect to the on-current.

If the characteristics of the diode D1 and the diode D2 are approximately equal, the on-voltage Von of the normal inspection target part A shown in the graph G1 and the defective inspection target part A shown in the graph G2 are determined as shown in FIG. is substantially equal to the on-voltage Von of . The first current value Ia is a current value (0.4 mA in graph G2) at which the voltage across the defective inspection target part A becomes the on-voltage Von. On the other hand, as shown in FIG. 3, the current value (0.8 mA in graph G1) at which the voltage across the normal inspection target part A becomes the on-voltage Von is the voltage across the defective inspection target part A. It becomes larger than the current value that becomes the on-voltage Von. Therefore, the first current value Ia obtained through the processing of steps S1 to S17 is equal to or less than the reference current value IS.

Note that steps S1 to S17 use a normal circuit board as a reference sample, and step S17 shows an example in which the first current value Ia of the inspection target part A in which one of the current paths A1 and A2 is disconnected is calculated. Ta. However, in step S1, a defective circuit board in which one of the current paths A1 and A2 is actually disconnected may be used, and in step S17, I(m) may be directly set as the first current value Ia.

As described above, through the processing in steps S6 to S17, the on-voltage search unit 53 obtains the on-voltage Von of the inspection target portion A of the reference sample based on the changes in the plurality of voltage values V(1) to V(10). be able to.

Next, the on-voltage search unit 53 measures the voltage between the probes Pr1 and Pr2 as a voltage value Vg while flowing the current of the first current value Ia between the probes Pr1 and Pr2 (step S18). Thereby, the on-voltage search unit 53 measures the voltage between the pads Pa5 and Pa6 as the voltage value Vg during the period when the current of the first current value Ia is flowing between the pads Pa5 and Pa6 of the inspection target part A. .

Now, since the first current value Ia is 0.4 mA, according to the example of graph G1 in FIG. 3, 0.14V is obtained as the voltage value Vg.

Next, the on-voltage search unit 53 calculates a determination voltage Vref for determining the quality of the inspection target part A based on the voltage value Vg, and stores this in the storage unit 54 (step S19). Specifically, for example, when variation or measurement error in the voltage value Vg is assumed to be at most 10%, the determination voltage Vref is calculated by multiplying the voltage value Vg by 1.1. Now, since the voltage value Vg is 0.14V, 0.15V is obtained as the determination voltage Vref.

Thereby, even if an error occurs in the voltage value Vg due to manufacturing variation or measurement error, a determination voltage Vref that allows accurate determination can be obtained.

As described above, through the processing of steps S1 to S19, the first current value Ia and the determination voltage Vref are stored in the storage unit 54, that is, are set in advance.

Note that the inspection device 1 does not necessarily need to include the on-voltage search section 53. For example, the user may experimentally obtain the first current value Ia and the determination voltage Vref using a method similar to steps S1 to S19, store them in the storage unit 54, and set them in advance. Alternatively, the user may draw the graphs G1 and G2 shown in FIG. 3 and store the first current value Ia and the determination voltage Vref read from the graphs G1 and G2 in the storage unit 54 to set them in advance. .

Next, the operations of the measurement processing section 51 and determination section 52 shown in FIG. 1 will be explained based on FIG. 8. First, for example, a user places the circuit board 100 to be inspected on a mounting table (not shown). Then, the measurement processing unit 51 brings the probe Pr1 into contact with the pad Pa5, and brings the probe Pr2 into contact with the pad Pa6 (step S21).

Next, the measurement processing unit 51 reads the first current value Ia from the storage unit 54. Then, the measurement processing unit 51 measures the voltage between the probes Pr1 and Pr2 as the first voltage value Va while passing the current of the first current value Ia between the probes Pr1 and Pr2 (step S22). Thereby, the measurement processing unit 51 measures the voltage between the pads Pa5 and Pa6 as the first voltage value Va during the period when the current of the first current value Ia is flowing between the pads Pa5 and Pa6 of the inspection target part A. do.

Now, since the first current value Ia is 0.4 mA, according to the example shown in FIG. 3, if the inspection target part A is normal, 0.14 V is measured as the first voltage value Va as shown in the graph G1. If the part A to be inspected is defective, 0.30V will be measured as the first voltage value Va, as shown in graph G2.

Next, the determination unit 52 reads the determination voltage Vref from the storage unit 54. Then, the determination unit 52 compares the first voltage value Va and the determination voltage Vref (step S23). If the first voltage value Va is equal to or less than the determination voltage Vref (YES in step S23), the determination unit 52 determines that the inspection target portion A is normal (step S24). The determination unit 52 displays the determination result on, for example, a display device (not shown), transmits it to the outside, or stores it in the storage unit 54 (step S26), and ends the process.

In the example shown in FIG. 3, if the inspection target part A is normal, the first voltage value Va is 0.14V from the graph G1, which is equal to or lower than the determination voltage Vref (=0.15V) (YES in step S23). The inspection target part A is correctly determined to be normal.

On the other hand, if the first voltage value Va exceeds the determination voltage Vref (NO in step S23), the determination unit 52 determines that the inspection target part A is defective (step S25). The determination unit 52 displays the determination result on, for example, a display device (not shown), transmits it to the outside, or stores it in the storage unit 54 (step S26), and ends the process.

In the example shown in FIG. 3, if the part A to be inspected is defective, the first voltage value Va becomes 0.30V from the graph G2, which exceeds the determination voltage Vref (=0.15V) (NO in step S23), so it is correctly detected. The inspection target part A is determined to be defective.

Here, the first current value Ia is determined by flowing a current of the first current value Ia to the inspection target part A in which one of the plurality of current paths is disconnected, that is, the defective inspection target part A by the processing of steps S1 to S17. The current value is set to such a value that the voltage between both ends of the inspection target part A becomes substantially the on-voltage Von in this case.

As a result, as shown in FIG. 3, when a current of the first current value Ia is passed through the test target part A, the voltage across the test target part A is 0 in the normal test target part A (graph G1). .14V, and 0.30V in the defective inspection target part A (graph G2), so the voltage difference Vd1 is 0.16V.

On the other hand, if the first current value Ia is a current that, when a current of the first current value Ia flows through a normal test target part A, the voltage between both ends of the test target part A becomes substantially the ON voltage Von. For example, in the case of FIG. 3, the first current value Ia is 0.8 mA, and the voltage across the test target part A is 0.8 mA in the normal test target part A (graph G1). 30V, and 0.32V in the defective inspection target part A (graph G2), so the voltage difference Vd2 is 0.02V.

That is, in the example shown in FIG. 3, when the first current value Ia is passed through the defective inspection target part A, the voltage across the inspection target part A becomes substantially the on-voltage. By setting the current value to Von, when a current of the first current value Ia is passed through a normal test target part A, a current value at which the voltage between both ends of the test target part A becomes substantially the on-voltage Von. The difference between the first voltage value Va between the normal state and the defective state is Vd1/Vd2=0.16/0.02=8 times larger than when the first voltage value Va is set to .

The larger the difference between the first voltage value Va between the normal state and the defective state, the easier it is to determine whether or not it is normal. Therefore, the first current value Ia is set to a current value at which, when a current of the first current value Ia is passed through the defective inspection target part A, the voltage between both ends of the inspection target part A becomes substantially the ON voltage Von. By doing so, when the current of the first current value Ia is passed through the normal test target part A, the voltage across the test target part A is set to a current value that becomes substantially the on-voltage Von. It is possible to easily determine whether or not it is normal.

Note that the first current value Ia is not necessarily a current value at which the voltage between both ends of the inspection target part A becomes substantially the on-voltage Von when a current of the first current value Ia is passed through the defective inspection target part A. You don't have to. For example, the first current value Ia is set to a current value smaller than the reference current value IS (0.8 mA in FIG. 3). Furthermore, when the first current value Ia is applied to the defective inspection target part A, the current value at which the voltage between both ends of the inspection target part A becomes substantially the on-voltage Von (Fig. The current value shall be 0.4 mA) or higher. In this way, from FIG. 3, the voltage difference between the normal graph G1 and the defective graph G2 becomes larger than when the first current value Ia exceeds 0.8 mA, and therefore the determination becomes easier. I understand that.

Moreover, from FIG. 3, even when the first current value Ia is smaller than 0.4 mA and 0.1 mA or more, the normal state is lower than when the first current value Ia exceeds 0.8 mA. It can be seen that the difference between the first voltage value Va at the time of failure and the first voltage value Va at the time of failure becomes large, and therefore the determination becomes easy.

Note that the inspection apparatus 1 does not necessarily need to include the determination section 52, and does not necessarily need to execute steps S23 to S25. Since the first voltage value Va reflects information indicating whether the inspection target part A is normal or not, the inspection of the inspection target part A is performed by obtaining the first voltage value Va by the measurement processing section 51. becomes easier.

Moreover, although the inspection target part A showed an example in which two current paths A1 and A2 were connected in parallel, the number of current paths connected in parallel may be three or more. For example, when a current path A3 (not shown) is connected in parallel in addition to current paths A1 and A2, if the characteristics of current path A3 are approximately the same as those of current paths A1 and A2, the current-voltage characteristics will be 9.

Graph G3 shown in FIG. 9 shows the characteristics under normal conditions, graph G4 shows the characteristics when one of the three current paths is disconnected, and graph G5 shows the characteristics when two of the three current paths are disconnected. It shows. Graph G5 is the same as graph G2 when one current path is disconnected in FIG. 3 where two current paths A1 and A2 are connected in parallel.

In this way, even when three current paths are connected in parallel, the on-voltage search unit 53 calculates the on-voltage Von, the determination voltage Vref, and the first current value Ia by the same process as steps S1 to S19. can be obtained.

In this case, the on-voltage Von=0.30V, the first current value Ia=0.80mA, the voltage value Vg=0.195V, and the determination voltage Vref=0.215V. Then, based on the determination voltage Vref (=0.215V) and the first current value Ia (=0.8mA) obtained in this way, the first voltage value Va can be measured and the part to be inspected can be inspected.

In this case, when a current of the first current value Ia is passed through a part A to be inspected where only one of the plurality of current paths is disconnected, the voltage between both ends of the part A to be inspected is By setting the current value to substantially the on-voltage Von, the voltage difference Vd3 between the judgment voltage Vref and the first voltage value Va in the failure graph G4 becomes 0.30-0.215=0.085V.

On the other hand, the first current value Ia of the inspection target part A where the remaining current paths except one among the plurality of current paths are disconnected is determined in step S17 by setting the first current value Ia=I(m)/Q. It is determined by The first current value Ia obtained by I(m)/Q is obtained when a current of the first current value Ia is passed through the inspection target part A where the remaining current paths except one among the plurality of current paths are disconnected. Then, the voltage between both ends of the part to be inspected A becomes a current value that substantially becomes the on-voltage Von. In this case, as shown in parentheses in FIG. 9, the first current value Ia is 0.40 mA, the voltage value Vg is 0.09 V, and the judgment voltage Vref is 0.10 V. The voltage difference Vd4 with one voltage value Va is 0.14-0.10=0.04V.

That is, the voltage difference Vd3 is larger than the voltage difference Vd4. Therefore, rather than obtaining the first current value Ia based on the inspection target part A in which the remaining current paths except one among the plurality of current paths are disconnected, Obtaining the first current value Ia based on A increases the difference between the first voltage value Va between normal and defective times, making it easier to determine whether the current is normal or not.

Therefore, when a current of the first current value Ia is passed through a part A to be inspected where only one of the plurality of current paths is disconnected, the voltage between both ends of the part A to be inspected is substantially It is more preferable to set the current value to the on-voltage Von.

On the other hand, as shown in FIG. 9, the voltage difference Vd4 is larger than the voltage difference Vd5 between the normal graph G3 and the defective graph G4 when the first current value Ia is set equal to or higher than the reference current value IS. Therefore, when a current of the first current value Ia is passed through the inspection target part A in which the remaining current paths except one of the plurality of current routes are disconnected, the voltage between both ends of the inspection target part A becomes substantially Even when the current value is set to the on-voltage Von, the effect of making it easy to determine whether or not it is normal can be obtained.

Furthermore, when a current is passed through the inspection target part A in which the remaining current paths except one among the plurality of current routes are disconnected, the current value is such that the voltage between both ends of the inspection target part A becomes substantially the on-voltage Von. is the defective current value IE. Then, a normal graph G3 and a defective graph when the first current value Ia is set to a current range smaller than the reference current value IS (=1.2 mA) and greater than or equal to the defective current value IE (=0.4 mA) As shown in FIG. 9, the voltage difference with G4 is larger than the voltage difference Vd5, and therefore it is easy to determine whether or not it is normal.

Therefore, a current range smaller than the reference current value IS and greater than or equal to the defective current value IE can be suitably used as the first current value Ia.

Further, although an example has been shown in which the first voltage value Va generated in the inspection target part A is measured by flowing a current of the first current value Ia to the inspection target part A, the following method may be used. That is, as shown in FIG. 10, the inspection device 1c may include a voltage supply section 2c such as a constant voltage power supply circuit instead of the current supply section 2, for example. Then, the measurement processing unit 51c applies a first voltage value Va substantially equal to or lower than the on-voltage Von to the inspection target unit A by the voltage supply unit 2c, and calculates a first current value Ia generated in the inspection target unit A. The current measurement unit 4 may be used to measure the current. Then, the determination unit 52c may determine the quality of the inspection target portion A based on the first current value Ia measured by the current measurement unit 4.

The first current value Ia obtained in this way also reflects information indicating whether the inspection target part A is normal or not, so by obtaining the first voltage value Va by the measurement processing section 51, Inspection of the inspection target part A becomes easier.
(Second embodiment)

Next, an inspection apparatus 1a according to a second embodiment of the present invention will be described based on FIG. 11. The inspection apparatus 1a shown in FIG. 11 differs from the inspection apparatus 1 shown in FIG. 1 in the configuration of a control section 5a. The control unit 5a further includes a reference slope acquisition unit 55. The measurement processing section 51a, the determination section 52a, and the on-voltage search section 53a operate differently from the measurement processing section 51, the determination section 52, and the on-voltage search section 53.

Further, like the testing device 1, the testing device 1a does not need to include the on-voltage search section 53a. The rest of the configuration is the same as the inspection device 1 according to the first embodiment, so the explanation thereof will be omitted, and the characteristic points of this embodiment will be explained below.

The on-voltage search unit 53a stores the first current value Ia in the storage unit 54 by setting the first current value Ia=I(m) in step S17 shown in FIG. Further, the on-voltage search unit 53a does not need to execute steps S18 and S19. In other respects, it is similar to the on-voltage search section 53.

According to the on-voltage search unit 53a, similarly to the on-voltage search unit 53, the on-voltage Von of the inspection target part A is searched, and the searched on-voltage Von and the first current value Ia are stored in the storage unit 54. This is set in advance.

The reference slope acquisition unit 55 acquires, as a reference slope rs, the slope of the current-voltage characteristic in a region where the voltage between both ends of the inspected portion A of the normal reference sample is equal to or lower than the on-voltage Von.

The measurement processing unit 51a measures the voltage between the pads Pa5 and Pa6 as a first voltage value Va while flowing a current having a first current value Ia between the pads Pa5 and Pa6, and generates a second current smaller than the first current value Ia. The voltage between pads Pa5 and Pa6 is measured as a second voltage value Vb while flowing a current of value Ib between pads Pa5 and Pa6.

The determination unit 52a determines the current of the inspection target portion A based on the ratio of the difference between the first current value Ia and the second current value Ib and the difference between the first voltage value Va and the second voltage value Vb, that is, the current of the inspection target part A - The quality of the part to be inspected A is determined based on the slope rt of the voltage characteristic. Specifically, the determination unit 52a determines whether the inspection target portion A is good or bad by comparing the slope rt with the reference slope rs.

Next, the operations of the reference slope acquisition section 55, measurement processing section 51a, and determination section 52a configured as described above will be explained based on FIGS. 12 and 13.

First, for example, a user places a normal circuit board 100 as a reference sample on a mounting table (not shown). Then, the reference slope acquisition unit 55 brings the probe Pr1 into contact with the pad Pa5, and brings the probe Pr2 into contact with the pad Pa6 (step S31).

Next, the reference slope acquisition unit 55 reads the on-voltage Von of the normal inspection target portion A from the storage unit 54, and sets the first voltage value Va to a value equal to the on-voltage Von (step S32).

Next, the reference slope acquisition unit 55 reads the first current value Ia of the normal inspection target portion A from the storage unit 54, and sets a value smaller than the first current value Ia as the second current value Ib (step S33). For example, in the example shown in FIG. 13, the first voltage value Va=on voltage Von=0.30V, and the first current value Ia=0.8 mA. In the graph G1 of the normal inspection target part A, a point with coordinates (Va, Ia)=(0.30, 0.8) is shown as a point P1.

The reference slope acquisition unit 55 can set the second current value Ib to 0.3 by subtracting a preset number, for example, 0.5 from the first current value Ia, which is 0.8. can. Alternatively, the reference slope acquisition unit 55 may obtain the first current value Ia by multiplying the first current value Ia by a coefficient greater than 0 and smaller than 1, such as multiplying the first current value Ia by 1/2 or 1/3. Two current values Ib may also be obtained.

Next, the reference slope acquisition unit 55 causes a current of a second current value Ib to flow between the probes Pr1 and Pr2, and sets the voltage between the probes Pr1 and Pr2 as the second voltage value Vb during the period in which the current is flowing. Measure (step S34). When the second current value Ib is, for example, 0.3 mA, 0.10V is obtained as the second voltage value Vb in the graph G1 of the normal inspection target part A shown in FIG. In the graph G1 of the normal inspection target part A, a point with coordinates (Vb, Ib)=(0.10, 0.3) is shown as a point P2.

Next, the reference slope acquisition unit 55 calculates the reference slope rs based on the following equation (4) (step S35).

Reference slope rs=(Ia-Ib)/(Va-Vb)...(4)

In the case of graph G1 in FIG. 13, the reference slope rs=(0.8-0.3)/(0.30-0.10)=2.5.

The reference slope rs corresponds to the slope of the straight line connecting the point P1 and the point P2 in the graph G1 of the normal inspection target part A. The reference slope acquisition unit 55 sets the second current value Ib and the reference slope rs obtained in steps S31 to S35 in advance by storing them in the storage unit 54, and ends the process.

Note that the inspection device 1a does not necessarily need to include the reference inclination acquisition section 55. For example, the user may experimentally obtain the reference slope rs using a method similar to steps S31 to S35, store it in the storage unit 54, and set it in advance. Alternatively, the user may draw the graph G1 shown in FIG. 13, read the slope of the straight line L1 as the reference slope rs, store the read reference slope rs and the second current value Ib in the storage unit 54, and set it in advance. You can also do this.

Referring to FIG. 14, first, for example, a user places the circuit board 100 to be inspected on a mounting table (not shown). Then, the measurement processing unit 51a brings the probe Pr1 into contact with the pad Pa5, and brings the probe Pr2 into contact with the pad Pa6 (step S41).

Next, the measurement processing unit 51a reads the first current value Ia from the storage unit 54. Then, the measurement processing unit 51a causes a current of a first current value Ia to flow between the probes Pr1 and Pr2, and measures the voltage between the probes Pr1 and Pr2 as a first voltage value Va during the period when the current is flowing. (Step S42). For example, in the case of FIG. 13, if the inspection target part A is normal, the first voltage value Va=0.30V is measured at the point P1 in the graph G1. On the other hand, if either current path A1 or A2 is disconnected and inspection target part A is defective, first voltage value Va=0.32V is measured at point P3 in graph G2.

Next, the measurement processing unit 51a reads the second current value Ib from the storage unit 54. Then, the measurement processing unit 51a causes a current of a second current value Ib to flow between the probes Pr1 and Pr2, and measures the voltage between the probes Pr1 and Pr2 as a second voltage value Vb during the period when the current is flowing. (Step S43). For example, in the case of FIG. 13, if the inspection target part A is normal, the second voltage value Vb=0.10V is measured at point P2 in the graph G1. On the other hand, if either current path A1 or A2 is disconnected and inspection target part A is defective, second voltage value Vb=0.22V is measured at point P4 in graph G2.

Next, the determination unit 52a calculates the slope rt based on the following equation (5) (step S44).

Slope rt=(Ia-Ib)/(Va-Vb)...(5)

The slope rt indicates the slope of the straight line L1 connecting the point P1 and the point P2 in the graph G1 if the inspection target part A is normal. On the other hand, if the part A to be inspected is defective, the slope rt indicates the slope of the straight line L2 connecting the point P3 and the point P4 in the graph G2. As is clear from the straight lines L1 and L2 in FIG. 13, when the part A to be inspected is defective, the slope rt is larger than when it is normal.

According to the example shown in FIG. 13, when the inspection target part A is normal, the slope rt=(0.8-0.3)/(0.30-0.10)=2.5. On the other hand, if the part A to be inspected is defective, the slope rt=(0.8-0.3)/(0.32-0.22)=5.

Next, the determination unit 52a calculates a determination value rth for determining the quality of the inspection target portion A based on the reference slope rs (step S45). Specifically, for example, when the variation in the reference slope rs and the measurement error are assumed to be at most 10%, the reference slope rs is multiplied by 1.1 to calculate the determination value rth. For example, if the reference slope rs=2.5, the determination value rth=2.5×1.1=2.75.

Thereby, even if an error due to manufacturing variation or measurement error occurs with respect to the reference slope rs, a determination value rth that can be correctly determined can be obtained.

Next, the determination unit 52a compares the slope rt and the determination value rth (step S46). If the slope rt is equal to or less than the determination value rth (NO in step S46), the determination unit 52a determines that the inspection target portion A is normal (step S47). The determination unit 52a displays the determination result on, for example, a display device (not shown), transmits it to an external device, or otherwise stores it in the storage unit 54, and ends the process.

On the other hand, if the slope rt exceeds the determination value rth (YES in step S46), the determination unit 52a determines that the inspection target part A is defective (step S48). The determination unit 52a displays the determination result on, for example, a display device (not shown), transmits it to the outside, or otherwise stores it in the storage unit 54, and ends the process (step S26).

In the example shown in FIG. 13, if the inspection target part A is normal, the slope rt will be 2.5 as described above, and the judgment value rth = 2.75 or less (NO in step S46), so the inspection target will be correctly inspected. Part A is determined to be normal. On the other hand, if the part A to be inspected is defective, the slope rt is 5 as described above and exceeds the determination value rth=2.75 (YES in step S46), so it is correctly determined that the part A to be inspected is defective. be done.

In formula (5), (Ia-Ib) is the difference between the first current value Ia and the second current value Ib, and (Va-Vb) is the difference between the first voltage value Va and the second voltage value Vb. Therefore, the slope rt is the ratio of the difference between the first current value Ia and the second current value Ib and the difference between the first voltage value Va and the second voltage value Vb. Therefore, the determination unit 52a determines whether the inspection target portion Determine whether A is good or bad.

As described above, according to steps S41 to S48, the first current value Ia is set to a current value at which the on-voltage Von is substantially obtained in the normal inspection target part A, and the second current value Ib is set to the first current value The current value is set to be smaller than Ia. As a result, the point P1 corresponding to the on-voltage Von in the normal inspection target part A becomes the end on the high voltage and high current side of the straight line L1, and the point P2 becomes the end on the low voltage and low current side of the straight line L1. .

Since the first voltage value Va and the second voltage value Vb are obtained based on the first current value Ia and the second current value Ib, if the inspection target part A is defective, As shown in graph G2 of FIG. 13, point P3 corresponding to the first current value Ia is located on the higher voltage side than the on-voltage of graph G2, that is, in a region where graph G2 rises steeply and has a large slope.

As a result, the straight line L2 when the inspected part A is defective has a slope rt greater than the straight line L1 when the inspected part A is normal. Therefore, according to steps S41 to S48, it is easy to inspect the inspection target part A based on the slope rt of the straight lines L1 and L2.

In addition, although the inspection target part A has shown an example in which two parallel-connected current paths A1 and A2 are connected in parallel, the number of parallel-connected current paths may be three or more. For example, when a current path A3 (not shown) is connected in parallel in addition to current paths A1 and A2, if the characteristics of current path A3 are approximately the same as those of current paths A1 and A2, the current-voltage characteristics will be 15.

Graphs G3, G4, and G5 shown in FIG. 15 are the same as graphs G3, G4, and G5 shown in FIG. 9.

In this way, even if the three current paths are connected in parallel, the on-voltage search unit 53a changes the upper limit of the current value from 1.0 to about 1.4 in step S7, so that the On-voltage Von (=0.30V) and first current value Ia (=1.2mA) in graph G3 can be obtained.

Then, based on the first current value Ia (=1.2 mA) obtained in this way, the reference slope acquisition unit 55 calculates the reference slope rs by the same process as steps S31 to S35 shown in FIG. be able to. Graph G3 shown in FIG. 15 shows an example in which 1/3 of the first current value Ia is set to the second current value Ib (=0.4 mA) in step S33. In the case of graph G3, the point with the first current value Ia (=1.2 mA) and the first voltage value Va (=0.30 V) is the point P5, the second current value Ib (=0.4 mA), and the second voltage value The point of Vb (=0.09V) becomes point P6. The slope of the straight line L3 connecting point P5 and point P6, that is, the reference slope rs=(1.2-0.4)/(0.30-0.09)=3.8.

Further, the measurement processing unit 51a and the determination unit 52a can correctly determine the defects in the graphs G4 and G5 by performing the same processing as steps S41 to S48 shown in FIG. For example, in the case of graph G4, the point with the first current value Ia (=1.2 mA) and the first voltage value Va (=0.31 V) is the point P7, and the point with the second current value Ib (=0.4 mA) and the second The point of voltage value Vb (=0.14V) becomes point P8. The slope rt of the straight line L4 connecting point P7 and point P8 is rt=(1.2-0.4)/(0.31-0.14)=4.7.

Therefore, since the slope rt (=4.7) of the straight line L4 is larger than the determination value rth (=3.8×1.1=4.2) (YES in step S46), the determination unit 52a determines that the graph G4 The inspection target part A can be correctly determined to be defective.

For example, in the case of graph G5, the point with the first current value Ia (=1.2 mA) and the first voltage value Va (=0.33 V) is the point P9, and the point with the second current value Ib (=0.4 mA) and the second The point of voltage value Vb (=0.30V) is point P10. The slope rt of the straight line L5 connecting point P9 and point P10 is rt=(1.2-0.4)/(0.33-0.30)=26.7.

Therefore, since the slope rt (=26.7) of the straight line L5 is larger than the determination value rth (=4.2) (YES in step S46), the determination unit 52a correctly identifies the inspection target part A of the graph G5 as defective. It can be determined that
(Third embodiment)

Next, an inspection apparatus 1b according to a third embodiment of the present invention will be described. The configuration of the inspection device 1b is shown in FIG. 1 similarly to the first embodiment. In FIG. 1, components different from those of the inspection device 1 are designated by reference numerals in parentheses. The inspection device 1b according to the third embodiment differs from the inspection device 1 according to the first embodiment in the configuration of a control section 5b. In the control section 5b, the measurement processing section 51b and the determination section 52b operate differently from the measurement processing section 51 and the determination section 52. Furthermore, the control section 5b includes an on-voltage search section 53a similar to the control section 5a instead of the on-voltage search section 53.

The rest of the configuration is the same as the inspection device 1 according to the first embodiment, so the explanation thereof will be omitted, and the characteristic points of this embodiment will be explained below.

The measurement processing unit 51b causes a current to flow between the probes Pr1 and Pr2 multiple times with different current values, measures the voltage between the probes Pr1 and Pr2 during each period in which each current flows, and calculates the measured voltage between the probes Pr1 and Pr2. The on-current Ion when the inspection target part A is turned on is obtained based on the change in voltage.

The determination unit 52b determines the quality of the inspection target part A based on the on-current Ion.

Next, the operation of the inspection apparatus 1b configured as described above will be explained. First, as described above, the on-voltage search unit 53a searches for the on-voltage Von of the inspection target part A, and stores the first current value Ia corresponding to the searched on-voltage Von in the storage unit 54. Set in advance. Note that in the third embodiment, the on-voltage search unit 53a does not need to execute step S16.

Referring to FIGS. 16 to 18, for example, a user places the circuit board 100 to be inspected on a mounting table (not shown). Then, the measurement processing unit 51b brings the probe Pr1 into contact with the pad Pa5, and brings the probe Pr2 into contact with the pad Pa6 (step S51). Thereafter, steps S2 to S8 and S11 to S15 similar to those in FIGS. 4 and 5 are executed by the measurement processing section 51b.

The measurement processing unit 51b causes a current to flow between the probes Pr1 and Pr2 multiple times with different current values through the processing of steps S2 to S7, and measures the voltage between the probes Pr1 and Pr2 during each period in which each current flows. do.

Next, the measurement processing unit 51b obtains the number m corresponding to the on-voltage Von from the maximum ratio R(m) obtained in step S15. Then, the measurement processing unit 51b refers to the measurement information stored in the storage unit 54 in step S5, and sets the current value I(m) of number m to the on-current Ion (step S61). In the example shown in FIG. 18, when a normal inspection target part A is measured, an on-current Ion of 0.8 mA is obtained, and when a defective inspection target part A is measured, an on-current Ion of 0.4 mA is obtained. You will get it.

As described above, through the processing in steps S6 to S61, the measurement processing unit 51b can obtain the on-current Ion of the inspection target part A based on the changes in the n voltage values V(1) to V(n). .

Next, the determination unit 52b uses the on-voltage search unit 53a to convert the on-current I(m) of the normal inspection target part A stored in the storage unit 54 in step S17 shown in FIG. 5 to the first current value Ia. Based on this first current value Ia, a determination value Iref for determining the quality of the inspection target part A is calculated (step S62). Specifically, for example, if the variation or measurement error in the first current value Ia is assumed to be 10% at most, the determination value Iref is calculated by multiplying the first current value Ia by 0.9. In the example of the graph G1 shown in FIG. 18, the first current value Ia=0.8, so the determination value Iref=0.8×0.9=0.72.

As a result, even if an error occurs in the on-current Ion due to manufacturing variation or measurement error, a determination value Iref that can be correctly determined can be obtained.

Next, the determination unit 52b compares the on-current Ion and the determination value Iref (step S63). If the on-current Ion exceeds the determination value Iref (YES in step S63), the determination unit 52b determines that the inspection target part A is normal (step S64). The determination unit 52b displays the determination result on, for example, a display device (not shown), transmits it to the outside, or otherwise stores it in the storage unit 54, and ends the process (step S26).

On the other hand, if the on-current Ion is less than or equal to the determination value Iref (NO in step S63), the determination unit 52b determines that the inspection target part A is defective (step S65). The determination unit 52b displays the determination result on, for example, a display device (not shown), transmits it to an external device, or otherwise stores it in the storage unit 54, and ends the process.

In the example shown in FIG. 18, if the inspection target part A is normal, the on-current Ion is 0.8 as shown in the graph G1, which exceeds the determination value Iref=0.72 (YES in step S63). , the inspection target part A is correctly determined to be normal. On the other hand, if the part A to be inspected is defective, the on-current Ion is 0.4 as shown in graph G2, which is less than the determination value Iref=0.72 (NO in step S63), so the part A to be inspected is correctly is determined to be defective.

As described above, according to the processes of steps S51 to S65, it is possible to correctly determine the quality of the part A to be inspected, and therefore, it is easy to inspect the part A to be inspected.

In addition, an example in which current is passed between the probes Pr1 and Pr2 in step S5 multiple times while changing the current value in step S4 shown in FIG. 16, and the voltage between the probes Pr1 and Pr2 is measured during each period in which each current flows. However, by executing steps S2a to S5a and S7a instead of steps S2 to S5 and S7 as shown in FIG. , Pr2, and measure the current flowing between the probes Pr1 and Pr2 during each period when each voltage is applied. Even in this case, through the processing in steps S6 to S61, the measurement processing unit 51b calculates the on-current Ion of the inspection target part A based on the changes in the n current values I(1) to I(n). can be obtained.

In addition, although the inspection target part A showed an example in which two current paths A1 and A2 were connected in parallel, the number of current paths connected in parallel may be three or more. For example, when a current path A3 (not shown) is connected in parallel in addition to current paths A1 and A2, if the characteristics of current path A3 are approximately the same as those of current paths A1 and A2, the current-voltage characteristics will be 20.

Graphs G3, G4, and G5 shown in FIG. 20 are the same as graphs G3, G4, and G5 shown in FIG. 9.

In this way, even if the three current paths are connected in parallel, the on-voltage search unit 53a changes the upper limit of the current value from 1.0 to about 1.4 in step S7, so that the The first current value Ia (=1.2 mA) in graph G3 can be obtained.

Then, the measurement processing unit 51b can obtain the on-current Ion through the processes of steps S51 to S61 shown in FIGS. 16, 17, and 19. The determination unit 52b can determine the quality of the inspection target part A based on the on-current Ion and the first current value Ia through the processes of steps S61 to S65 shown in FIG. When the first current value Ia=1.2 mA, the determination value Iref=1.2×0.9=1.08 (step S62).

In the case of graph G3, since the on-current Ion (=1.2) exceeds the determination value Iref (=1.08) (YES in step S63), the inspection target part A of graph G3 is correctly determined to be normal. (Step S64). In the case of graph G4, since the on-current Ion (=0.8) is less than or equal to the determination value Iref (=1.08) (NO in step S63), it is possible to correctly determine the inspection target part A of graph G4 as defective. It is possible (step S65). In the case of graph G5, since the on-current Ion (=0.4) is less than or equal to the determination value Iref (=1.08) (NO in step S63), it is possible to correctly determine the inspection target part A of graph G5 as defective. It is possible (step S65).

That is, in the inspection device according to an example of the present invention, when the forward voltage exceeds the on-voltage, a change in current with respect to a change in the voltage is larger than when the forward voltage is less than the on-voltage. This is an inspection device for inspecting a part to be inspected in which a plurality of current paths having diode characteristics are connected in parallel, and includes a current supply section that can supply current, a voltage measurement section that can measure voltage, and a preset a measurement processing section that causes the current supply section to flow a current having a first current value between the two terminals, and causes the voltage measurement section to measure the voltage between the terminals as the first voltage value; The current value is less than or equal to a current value at which the voltage across the normal inspection target section substantially becomes the on-voltage.

Further, in the inspection method according to an example of the present invention, a change in current with respect to a change in voltage when the forward voltage exceeds the on-voltage is larger than when the forward voltage is less than the on-voltage. An inspection method for inspecting a part to be inspected in which a plurality of current paths having diode characteristics are connected in parallel, the method comprising: flowing a current of a preset first current value between the two ends, and increasing the voltage between the two ends; The method includes a measurement processing step of measuring as a first voltage value, and the first current value is less than or equal to a current value at which the voltage across the normal inspection target portion becomes substantially the on-voltage.

Due to its characteristics, a portion to be inspected having diode characteristics exhibits a slight change in the voltage with respect to the flowing current in a region where the voltage between both ends exceeds the on-voltage. According to these configurations, when a first current value equal to or lower than the current value at which the voltage between both ends of the normal test target part becomes substantially on-voltage flows through the test target part, the voltage between both ends of the test target part flows through the test target part. is measured as the first voltage value. Then, in a region where the voltage across the normal test target part does not exceed the on-state voltage, the voltage generated between both ends of the current flowing through the test target part with the first current value is measured as the first voltage value. Therefore, when any one of the plurality of current paths is disconnected, a large change in the first voltage value appears. Therefore, since the first voltage value reflects information indicating whether or not the part to be inspected is normal, the inspection of the part to be inspected becomes easier by obtaining the first voltage value.

Moreover, it is preferable to further include a determination unit that determines the quality of the inspection target part based on the first voltage value.

According to this configuration, it is possible to determine whether the part to be inspected is good or bad based on the first voltage value.

Further, in the inspection device according to an example of the present invention, when the forward voltage exceeds the on-voltage, a change in current with respect to a change in the voltage is larger than when the forward voltage is less than the on-voltage. This is an inspection device for inspecting a part to be inspected in which a plurality of current paths having diode characteristics are connected in parallel, and includes a voltage supply section that can output voltage, a current measurement section that can measure current, and substantially While applying a voltage of a first voltage value preset below the on-voltage between both ends of the inspection target part by the voltage supply part, the current flowing between the ends is measured by the current measurement part to a first current value. and a measurement processing unit that performs measurement.

Further, in the inspection method according to an example of the present invention, a change in current with respect to a change in voltage when the forward voltage exceeds the on-voltage is larger than when the forward voltage is less than the on-voltage. An inspection method for inspecting a part to be inspected in which a plurality of current paths having diode characteristics are connected in parallel, the method comprising: applying a voltage of a first voltage value preset substantially below the on-voltage to the part to be inspected; The method includes a measurement processing step of applying a current between both ends and measuring a current flowing between the both ends as a first current value.

According to these configurations, a first voltage is applied between both ends of the part to be tested instead of the first current, and a current flowing between both ends of the part to be tested is measured as the first current instead of the first voltage. . Even in this case, the first current to be measured reflects information indicating whether the part to be inspected is normal or not, so by obtaining the first current, the part to be inspected can be easily inspected. Become.

Moreover, it is preferable to further include a determination unit that determines the quality of the inspection target part based on the first current value.

According to this configuration, it is possible to determine whether the part to be inspected is good or bad based on the first current value.

Moreover, it is preferable that the normal inspection target part is one in which all of the plurality of current paths are conductive.

If the plurality of parallel-connected current paths are all conductive, the part to be inspected is normal.

Further, the first current value is determined at both ends of the inspection target part when a current of the first current value is passed through the inspection target part in which the remaining current paths excluding one of the plurality of current paths are disconnected. It is preferable that the voltage between the two is substantially equal to or higher than the current value at which the on-voltage is reached.

According to this configuration, the first current value is less than or equal to a current value at which the voltage across the normal test target part becomes substantially on-voltage, and the remaining current value except for one of the plurality of current paths is The current range is set in advance to a current value that is equal to or higher than the current value at which the voltage between both ends of the inspected section becomes substantially on-voltage when a current of the first current value is passed through the inspected section whose current path is disconnected. There is. Such a current range is suitable as the first current value.

Further, the first current value is such that when a current of the first current value is passed through the part to be inspected in which only one of the plurality of current paths is disconnected, the voltage between both ends of the part to be inspected is substantially In general, it is preferable that the current value be equal to or higher than the current value at which the on-voltage is reached.

According to this configuration, the first current value is less than or equal to the current value at which the voltage between both ends of the normal inspection target section is substantially on-voltage, and only one of the plurality of current paths is disconnected. The current range is set in advance to a current value or higher at which a voltage across the test target section becomes substantially an on-voltage when a current of the first current value is passed through the test target part. Such a current range is suitable as the first current value.

Further, the first current value is such that when a current of the first current value is passed through the part to be inspected in which only one of the plurality of current paths is disconnected, the voltage between both ends of the part to be inspected is substantially It is preferable that the current value is such that the on-voltage is achieved.

According to this configuration, the first current value is such that when a current of the first current value is passed through a part to be inspected in which only one of the plurality of current paths is disconnected, the voltage between both ends of the part to be inspected is substantially The current value is set in advance to a value that will give an on-state voltage. In this case, the first current value is a current value at which the voltage between both ends of the test target section becomes substantially on-voltage when a current of the first current value is passed through a normal test target part. , there is a large difference in the first voltage values obtained between normal and defective conditions. Therefore, it becomes easier to determine the quality of the part to be inspected based on the first voltage value.

Further, the first current value is a current value at which the voltage between both ends of the normal inspection target section substantially becomes the on-state voltage, and the measurement processing section converts the current of the first current value into the current The voltage between the two ends is measured by the voltage measurement part as a first voltage value while being caused to flow between the two ends by the supply part, and the current having a second current value smaller than the first current value is caused to flow between the two ends by the current supply part. The test device measures the difference between the first current value and the second current value and the first voltage. It is preferable to further include a determination unit that determines the quality of the part to be inspected based on the ratio of the difference between the voltage value and the second voltage value.

According to this configuration, the ratio of the difference between the first current value and the second current value and the difference between the first voltage value and the second voltage value is determined by the first current value in the current-voltage characteristic graph of the part to be inspected. represents the slope of a straight line connecting the point where the current value and the first voltage value intersect and the point where the second current value and the second voltage value intersect. This slope is larger in a test target part where one of the plurality of current paths is disconnected than in a normal test target part. Therefore, the determination unit can determine the quality of the part to be inspected based on the above-mentioned inclination.

Further, the current supply section causes a current to flow between the two terminals multiple times while changing the current value, and the voltage measuring section measures the voltage between the two terminals during each period in which each of the currents flows. It is preferable to further include an on-voltage search unit that searches for an on-voltage of the inspection target portion based on the plurality of voltage changes.

According to this configuration, it is possible to search for the on-voltage of a portion to be inspected whose characteristics are unknown.

Further, in the inspection device according to an example of the present invention, when the forward voltage exceeds the on-voltage, a change in current with respect to a change in the voltage is larger than when the forward voltage is less than the on-voltage. An inspection device for inspecting a part to be inspected in which a plurality of current paths having diode characteristics are connected in parallel, wherein one of current or voltage is applied to both ends of the part to be inspected multiple times with different values. the other of the current or voltage between the two ends is measured during each period in which the one is supplied, and the current that turns on the inspected part based on the measured change in the other; and a determination unit that determines the quality of the part to be inspected based on the current acquired by the measurement processing unit.

Further, in the inspection method according to an example of the present invention, a change in current with respect to a change in voltage when the forward voltage exceeds the on-voltage is larger than when the forward voltage is less than the on-voltage. An inspection method for inspecting a part to be inspected in which a plurality of current paths having diode characteristics are connected in parallel, the method comprising: applying one of current or voltage to both ends of the part to be inspected multiple times with different values; the other of the current or voltage between the two ends is measured during each period in which the one is supplied, and the current that turns on the inspected part based on the measured change in the other; and a determination step of determining whether the inspection target part is good or bad based on the current acquired by the measurement processing section.

The current that is turned on in the test target part is larger in a normal test target part than in a test target part in which a disconnection occurs in one of the plurality of current paths. Therefore, according to these configurations, the current that turns on the part to be inspected is acquired, and the quality of the part to be inspected can be determined based on the current.

Further, an inspection device program according to an example of the present invention is an inspection device program for operating the above-mentioned inspection device, and causes a computer to function as the measurement processing section.

According to this program, the above-described inspection apparatus can be operated by causing the computer to function as the measurement processing section.

The inspection device, inspection method, and program for the inspection device having such a configuration can easily inspect an inspection target in which a plurality of diodes are connected in parallel.

This application is based on Japanese Patent Application No. 2018-228749 filed on December 6, 2018, and the contents thereof are included in the present application. Note that the specific embodiments or examples described in the Detailed Description section are merely for clarifying the technical contents of the present invention, and the present invention does not include such specific examples. It should not be construed in a narrow sense.

1, 1a, 1b Inspection device 2 Current supply section 3 Voltage measurement section 4 Current measurement section 5, 5a, 5b Control section 51, 51a, 51b Measurement processing section 52, 52a, 52b Judgment section 53, 53a On-voltage search section 54 Memory Section 55 Reference slope acquisition section 100 Circuit board 101 Wiring board 102 Parts A, B, C Parts to be inspected A1, A2, A3 Current paths D1, D2 Diodes G1, G2, G3, G4, G5 Graph I Current value Ia First current Value Ib Second current value Ion On-current Iref Judgment value IS Reference current value L1, L2, L3, L4, L5 Straight line P1 to P10 Points Pa1 to Pa6 Pads Pr1, Pr2 Probe R Ratio T1 to T4 Terminal V Voltage value Va 1st Voltage value Vb Second voltage value Vd1, Vd2 Voltage difference Vg Voltage value Von On-voltage Vref Judgment voltage W1 to W8 Wiring pattern rs Reference slope rt Slope rth Judgment value

Claims (12)

An inspection device for inspecting a part to be inspected in which a plurality of current paths including diodes are connected in parallel,
a current supply unit capable of supplying current;
a voltage measuring section capable of measuring voltage;
a measurement processing unit that causes the current supply unit to flow a current of a preset first current value between both ends of the inspection target part , and causes the voltage measurement unit to measure the voltage between the two ends as a first voltage value; Equipped with
The first current value is equal to or less than a current value at which the voltage between both ends of the normal inspection target section becomes substantially the ON voltage of the diode , and the remaining current excluding one of the plurality of current paths. An inspection device in which, when a current having the first current value is passed through the inspection target part whose path is broken, a voltage between both ends of the inspection target part is substantially equal to or higher than a current value at which the on-voltage becomes the on-state voltage . The inspection device according to claim 1, further comprising a determination unit that determines whether the inspection target portion is good or bad based on the first voltage value. An inspection device for inspecting a part to be inspected in which a plurality of current paths including diodes are connected in parallel,
a voltage supply unit capable of outputting voltage;
a current measuring section capable of measuring current;
Applying a voltage of a first voltage value that is preset substantially below the on-voltage of the diode between both ends of the inspection target part by the voltage supply part, and measuring a current flowing between the ends by the current measurement part. and a measurement processing unit that measures the first current value ,
When the remaining current paths excluding one of the plurality of current paths are applied between both ends of the inspection target part with a disconnection, the current flowing through the inspection target part is substantially An inspection device whose current value is equal to or higher than the on-voltage . The inspection device according to claim 3, further comprising a determination unit that determines whether the inspection target portion is good or bad based on the first current value. The first current value is such that when a current of the first current value is passed through the part to be inspected in which only one of the plurality of current paths is disconnected, the voltage between both ends of the part to be inspected is substantially The inspection device according to claim 1 or 2, wherein the current value is greater than or equal to the on-voltage. The first current value is such that when a current of the first current value is passed through the part to be inspected in which only one of the plurality of current paths is disconnected, the voltage between both ends of the part to be inspected is substantially The inspection device according to claim 5, wherein the current value is the on-voltage. The first current value is a current value at which the voltage across the normal inspection target portion substantially becomes the on-voltage,
The measurement processing section is further configured to cause the current supply section to flow a current having a second current value smaller than the first current value between the two terminals, and to set the voltage between the terminals to a second voltage value using the voltage measuring section. Let it be measured as,
The inspection device determines the quality of the part to be inspected based on the ratio of the difference between the first current value and the second current value and the difference between the first voltage value and the second voltage value. The inspection device according to claim 1, further comprising a determination section. The current supply section causes a current to flow between the two terminals multiple times while changing the current value, and the voltage measuring section measures the voltage between the two terminals during each period during which each of the currents flows, and the measured voltage is 8. The inspection apparatus according to claim 1 , further comprising an on-voltage search section that searches for an on-voltage of the inspection target section based on changes in a plurality of voltages. 9. The inspection apparatus according to claim 1, wherein all of the plurality of current paths are conductive in the normal inspection target part. An inspection method for inspecting a part to be inspected in which a plurality of current paths including diodes are connected in parallel,
A measurement processing step of flowing a current of a preset first current value between both ends of the inspection target part and measuring the voltage between the both ends as a first voltage value,
The first current value is equal to or less than a current value at which the voltage between both ends of the normal inspection target section becomes substantially the ON voltage of the diode , and the remaining current excluding one of the plurality of current paths. An inspection method in which, when a current having the first current value is passed through the inspection target part whose path is broken, a voltage between both ends of the inspection target part is substantially equal to or higher than the current value at which the on-voltage is obtained . An inspection method for inspecting a part to be inspected in which a plurality of current paths including diodes are connected in parallel,
A measurement processing step of applying a voltage of a first voltage value preset substantially below the on-voltage of the diode between both ends of the inspection target part, and measuring the current flowing between the both ends as a first current value. including;
When the remaining current paths excluding one of the plurality of current paths are applied between both ends of the inspection target part with a disconnection, the current flowing through the inspection target part is substantially An inspection method in which the current value is equal to or higher than the on-voltage . An inspection device program for operating the inspection device according to any one of claims 1 to 9 ,
A program for an inspection device that causes a computer to function as the measurement processing section.

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