KR20190036472A - Resistance measurement apparatus, substrate inspection apparatus, and resistance measurement method - Google Patents

Abstract

Provided are a resistance measurement apparatus, a substrate inspection apparatus, and a resistance measurement method, capable of easily improving resistance measurement precision using a four-terminal measurement method, comprising: a current probe (Pc1, Pc2) brought into contact with a chip-side electrode (A1); a detection probe (Pv1, Pv2) brought into contact with an outward electrode (A2); a voltage detection unit (4) for detecting a voltage between the detection probe (Pv1 and Pv2); a constant current source (CS1) with its positive electrode connected to the current probe (Pc1) and its negative electrode connected to a ground and outputting a current of a first current value (I_1); a constant current source (CS2) with its positive electrode connected to the negative electrode of the constant current source (CS1) and the ground and its negative electrode connected to the current Probe (Pc2) and outputting a current of a second current value (I_2) which is substantially the same as the first current value (I_1); a ground probe (PG) connecting a wiring (A3) to the ground; and a resistance obtaining unit (51) for obtaining a resistance of the wiring (A3) based on the voltage detected by the voltage detection unit (4).

Description

Technical Field [0001] The present invention relates to a resistance measuring device, a substrate inspection device, and a resistance measuring method.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance measuring apparatus for performing resistance measurement, a substrate inspection apparatus using the same, and a resistance measuring method.

BACKGROUND ART Conventionally, in order to inspect a wiring pattern formed on a substrate such as a printed wiring board, a resistance value of the wiring pattern is measured. In inspection of the wiring pattern, it is necessary to detect not only the presence or absence of disconnection, but also the defect that the width of the wiring pattern becomes narrow, the thickness becomes thin, and the disconnection does not reach the disconnection. In order to detect defects not reaching such disconnection, it is necessary to conduct resistance measurement with high accuracy. As such a high-precision resistance measuring method, a resistance measuring apparatus using a four-terminal measuring method is known (see, for example, Patent Document 1).

The resistance measuring apparatus disclosed in Patent Document 1 includes a pair of contact probes P1 and P2 for flowing a current for resistance measurement to a wiring pattern of a resistance measurement object and a pair of contact probes P1 and P2 for measuring a voltage of the resistance measuring point And contact probes P3 and P4.

According to the resistance measuring apparatus described in Patent Document 1, since the current for resistance measurement does not flow through the contact probes P3 and P4 for voltage measurement, the voltage drop due to the resistance of the contact probes P3 and P4 itself is reduced, It is possible to measure the resistance with high accuracy. In the resistance measuring apparatus described in Patent Document 1, the positive-electrode-side contact probe P1 for current output is connected to a constant current source and the negative-electrode-side contact probe P2 is connected to the circuit ground (see FIG. 1 ).

Japanese Patent Application Laid-Open No. 2004-184374 Japanese Patent Application Laid-Open No. 2007-333598

However, in the resistance measuring device described in Patent Document 1, a voltage for resistance measurement flows through the contact resistance between the contact probe P2 on the negative electrode side and the measurement object M, and a voltage is generated. This voltage becomes the common mode voltage (common mode noise) with respect to the contact probes P3 and P4 for voltage measurement. The contact resistance Ro of the contact probe P2 may be about 100 O. When the current i for resistance measurement is 20 mA, the common mode voltage Vc is Ro x i = 100 OMEGA x 20 MA = 2000 ㎷ (see Fig. 7).

On the other hand, for example, when the measurement object is a wiring pattern, its resistance value Rx is about 1 mΩ. Then, if the current (i) for resistance measurement is 20 mA, the measured voltage Vm measured by the contact probes P3 and P4 is Rx i = 1 m? X 20 mA = 20? = 0.02? 7).

Then, the measured voltage is 20 log (measured voltage / common mode voltage) = 20 log (0.02 / 2000) = -100 dB for the common mode voltage. Since the contact resistance generated by the contact of the contact probe P2 is unstable, the common mode voltage also fluctuates unstably. The measurement voltage becomes a microvoltage of about -100 dB with respect to the common mode voltage, so that the measurement voltage is influenced by the fluctuation of the common mode voltage and the measurement accuracy thereof is lowered. As a result, there is a problem that the accuracy of the resistance measurement value obtained based on the measured voltage is lowered.

As a method of setting the common mode voltage to zero, there is a method of canceling the common mode voltage with the output of the operational amplifier by feeding back the common mode voltage to the inverting amplifier circuit of the operational amplifier as described in Patent Document 2 I can think. Fig. 8 is an equivalent circuit diagram of the circuit described in Fig. 1 of Patent Document 2. Fig. The contact resistance and the like of the current supply terminals 22 and 23 and the voltage measurement terminals 24 and 25 in Patent Document 2 are represented by Ro and the parasitic capacitance is represented by Co.

However, in such a method, since the feedback delay time due to Ro or the parasitic capacitance Co, which is a resistance component of the feedback circuit, and the response delay of the operational amplifier occur, it is difficult to perform high-speed operation, It is not easy to cancel.

An object of the present invention is to provide a resistance measuring apparatus, a substrate inspecting apparatus, and a resistance measuring method which can easily improve the resistance measuring accuracy by the four-terminal measuring method.

A resistance measuring apparatus according to the present invention is a resistance measuring apparatus for measuring a resistance of a conductor, comprising: first and second current probes for bringing a predetermined measuring current into contact with the conductor; A first detection probe for detecting a voltage generated in the conductor by a current for measurement; a voltage detection unit for detecting a voltage between the first and second detection probes; and a positive electrode connected to the first current probe A first constant current source connected to the negative electrode of the first constant current source and configured to output a current having a predetermined first current value and a positive electrode connected to the negative electrode of the first constant current source and the ground, A second constant current source connected to the second current probe with a negative electrode and outputting a current of a second current value substantially equal to the first current value; Of the predetermined portion and a portion acquiring resistance for acquiring the resistance on the basis of the ground unit and the voltage detected by the voltage detecting section and to conduct the ground.

The resistance measuring method according to the present invention is a resistance measuring method for measuring a resistance of a conductor, comprising the steps of: (a) contacting the first current probe and the first detecting probe to the conductor; (b) Contacting the second current probe with the second detection probe at a position spaced apart from the contact position of the first current probe and the first detection probe, and (c) connecting the positive current probe to the first current probe The negative electrode of the first constant current source is connected to the negative electrode of the first constant current source and the ground, and the negative electrode of the first constant current source is connected in series with the first constant current source, Outputting a current of a second current value substantially equal to the first current value by a second constant current source having a negative electrode connected to the second current probe; and (d) (E) a step of detecting a voltage between the first and second detection probes; (f) a step of obtaining the resistance based on the voltage detected by the step (e) do.

According to these configurations, it is possible to perform the resistance measurement by the four-terminal measuring method using the first and second current probes and the first and second detecting probes. As a result of the first constant current source and the second constant current source whose connection points are connected in series and whose ground potential is to maintain the output currents of the first current value and the second current value, The current flowing from the predetermined portion to the ground becomes approximately zero. As a result, the common mode voltage becomes approximately zero. Since the resistance can be acquired based on the measured voltage measured while the common mode voltage is substantially zero, it is easy to improve the measurement accuracy of the resistance. Therefore, it is easy to improve the resistance measurement accuracy by the four-terminal measurement method.

It is preferable that the grounding unit includes a grounding probe for making contact with the predetermined portion, and the grounding probe is connected to the ground.

It is preferable that the step (d) is a step of bringing the ground probe connected to the ground into contact with the predetermined portion.

According to these structures, the grounding probe is brought into contact with a predetermined portion of the conductor, so that the conductor can be made conductive with the ground.

The ground portion may be a wiring for connecting the second detection probe to the ground.

Further, the second detection probe may be connected to the ground, and the step (b) may also serve as the step (d).

According to these configurations, since the second detection probe can also be used as a grounding probe, it is not necessary to separately form a grounding probe and contact the conductor.

In addition, a first electrode is formed on one end of the conductor, and a second electrode having a larger area than the first electrode is formed on the other end of the conductor. In the step (a) Wherein the step (b) is a step of bringing the second current probe and the second detection probe into contact with the second electrode, and the step (d) is a step of bringing the first current probe into contact with the first current probe, And bringing the second probe into contact with the second electrode by using the second probe as the predetermined portion.

According to this method, two probes are brought into contact with a first electrode having a small area, and three probes are brought into contact with a second electrode having a large area. Therefore, it is easy to bring the probes into contact with the first and second electrodes.

The board inspecting apparatus according to the present invention includes the above-described resistance measuring apparatus and a board inspecting section for inspecting the conductor wiring formed on the board based on the resistance measured by the resistance measuring apparatus .

According to this configuration, the wiring formed on the substrate can be inspected based on the resistance measured by the resistance measuring apparatus.

The resistance measuring apparatus, the substrate inspecting apparatus, and the resistance measuring method having such a configuration can easily improve the resistance measurement accuracy by the four-terminal measuring method.

1 is a block diagram showing an example of a configuration of a substrate inspection apparatus using a resistance measuring apparatus according to a first embodiment of the present invention.
2 is an explanatory view showing an equivalent circuit of the substrate inspection apparatus and the substrate shown in Fig.
3 is a flowchart showing an example of a resistance measuring method according to an embodiment of the present invention.
Fig. 4 is an explanatory diagram showing the connection of the substrate inspection apparatus when the IC is inspected. Fig.
5 is a block diagram showing an example of a configuration of a substrate inspecting apparatus using a resistance measuring apparatus according to a second embodiment of the present invention.
6 is an explanatory view showing an equivalent circuit of the substrate inspection apparatus and the substrate shown in Fig.
7 is an explanatory view for explaining common mode voltages related to the background art.
Fig. 8 is an equivalent circuit diagram of the circuit described in Fig. 1 of Patent Document 2. Fig.

Best Mode for Carrying Out the Invention Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment)

1 is a block diagram showing an example of a configuration of a substrate inspection apparatus 1 using a resistance measuring apparatus according to a first embodiment of the present invention. In the drawings, the same reference numerals denote the same components, and a description thereof will be omitted.

The substrate inspecting apparatus 1 (resistance measuring apparatus) shown in Fig. 1 includes a constant current source CS1 (a first constant current source), a constant current source CS2 (a second constant current source), a voltage detecting unit 4, (First detection probe) Pc1 (first current probe), a current probe Pc2 (second current probe), a detection probe Pv1 (first detection probe), a detection probe Pv2 (Ground), the scanner 6, and the control unit 5. [

Fig. 1 shows a state in which each probe of the substrate inspection apparatus 1 is in contact with the substrate A to be inspected. The substrate inspection apparatus 1 is configured to perform resistance measurement by a so-called four-terminal measurement method. A portion of the substrate inspection apparatus 1 excluding the substrate inspection section 52, which will be described later, corresponds to an example of the resistance measurement apparatus.

The substrate to be inspected may be a substrate such as a package substrate for a semiconductor package, an interposer substrate, a film carrier, a printed wiring board, a glass epoxy substrate, a flexible substrate, a ceramic multilayer wiring substrate, Or a transparent conductive plate for a touch panel, or a semiconductor substrate such as a semiconductor wafer, a semiconductor chip, or a semiconductor substrate such as a CSP (Chip Size Package), or the like.

The substrate to be inspected may be a component-embedded substrate (embedded substrate) in which an electronic component such as a semiconductor chip is buried. The object to be inspected is not limited to the substrate but may be an electronic component such as a semiconductor chip. Inspection points such as a wiring pattern, a pad, a land, a solder bump, and a terminal are formed on a substrate or an electronic component to be inspected.

1 illustrates a cross-sectional view of an interposer substrate for a semiconductor package as a substrate A to be inspected. On one surface of the substrate A, a plurality of chip-side electrodes A1 (first electrodes) connected to the semiconductor chip are formed. The interval between the plurality of chip side electrodes A1 is narrowed in accordance with the fine electrode pitch of the semiconductor chip and the size of the chip side electrode A1 is also small. On the other surface of the substrate A, a plurality of outward electrodes A2 (second electrodes) for connecting the semiconductor chip to the outside are formed.

The plurality of outward electrodes A2 are, for example, arranged in a lattice pattern and formed into a ball grid connected to the outside by solder balls. The interval between the plurality of outward electrodes A2 is wider than the interval between the chip side electrodes A1 to facilitate wiring with the outside and the size of the outgoing electrode A2 is also larger than the chip side electrode A1 .

Each chip-side electrode A1 and each of the outward electrodes A2 are connected to each other by a wiring A3 (conductor) formed to penetrate the thickness direction of the substrate A, respectively. The substrate inspection apparatus 1 measures and checks the resistance value Rx of each of the wirings A3. The wiring A3 corresponds to one example of the conductor and the chip side electrode A1 corresponds to one end of the wiring A3 and the outgoing electrode A2 corresponds to the other end of the wiring A3.

The current probes Pc1 and Pc2, the detection probes Pv1 and Pv2 and the grounding probe PG are constituted as inspection jigs which can be detached from the substrate inspection apparatus 1, for example. Hereinafter, the current probes Pc1 and Pc2, the detection probes Pv1 and Pv2, and the ground probe PG may be simply described as probes Pc1, Pc2, Pv1, Pv2, and PG.

The probes Pc1, Pc2, Pv1, Pv2, and PG are wire-like contacts having, for example, elasticity (flexibility) with diameters of about 100 m to 200 m. The current probes Pc1 and Pc2 and the detection probes Pv1 and Pv2 are formed of a metal or other conductor such as tungsten, high-speed steel SKH, or beryllium copper Be-Cu.

The tips of the current probe Pc1 and the detection probe Pv1 are brought into contact with the chip side electrode A1 of the substrate A. [ The tip of the current probe Pc2, the detection probe Pv2 and the grounding probe PG are brought into contact with the outward electrode A2 at a position separated from the chip-side electrode A1. When the probes are brought into contact with the chip side electrode A1 and the outward electrode A2 in this manner, two probes are brought into contact with the chip side electrode A1 having a small and narrow pitch, So that three probes are brought into contact with the outward electrode A2 having a wide pitch. Therefore, it is easy to bring the probes into contact with the chip side electrode A1 and the outward electrode A2.

In FIG. 1, each of the probes Pc1, Pc2, Pv1, Pv2, and PG is described by simplifying the illustration. In some cases, hundreds to thousands of checkpoints are set for one substrate, Pc1, Pc2, Pv1, Pv2, and PG, respectively, corresponding to several hundreds to several thousands of probes.

The scanner 6 detects the connection relationship between the current probes Pc1 and Pc2 and the constant current sources CS1 and CS2 and the connection relationship between the detection probes Pv1 and Pv2 and the voltage detector 4, ) And the ground. The scanner 6 is provided with a plurality of switches including switches 61, 62, 63, 64 and 65, for example. The switches such as the switches 61, 62, 63, 64 and 65 are various switching elements such as semiconductor switches such as transistors and relay switches. Each switch is turned on and off in accordance with a control signal from the control unit 5, for example.

The constant current sources CS1 and CS2 are constant current circuits for causing a constant current to flow, and a constant current for measurement flows in the wiring A3. As the constant current sources CS1 and CS2, various circuits known as a constant current circuit such as a transistor or a Zener diode or a current mirror circuit can be used, or a switching power supply circuit or the like is used .

The positive constant current source CS1 has its positive electrode connected to the current probe Pc1 through the switch 61 and the negative electrode connected to the ground GND. The constant current source CS1 outputs the current of the first current value I ₁ set in advance to the current probe Pc1 from the positive (+) thereof. The first current value I ₁ is, for example, about 20 mA.

The positive constant current source CS2 is connected in series with the constant current source CS1 and the positive polarity thereof is connected to the negative polarity of the constant current source CS1 and the ground GND and the negative polarity thereof is connected to the switch 62 To the current probe Pc2. A constant current source (CS2) is a constant current source (CS1) from the positive electrode (+), and outputs a current of a first current value (I ₁₎ substantially equal to a second current value to (I _2). Here, the fact that they are substantially the same means that they are regarded as the same even if there is a difference in the degree of production caused by manufacturing variations of the constant current sources CS1 and CS2, current control precision, and the like.

The ground (GND) is the circuit ground of the substrate inspection apparatus 1. The ground GND may be the frame ground (earth ground) of the substrate inspection apparatus 1, but the circuit ground is more preferable.

The switch 61, the current probe Pc1 and the chip-side electrode A1 from the ground GND when the switches 61, 62, 63, 64 and 65 are turned on by the control unit 5, A current loop of the measuring current I returning to the ground GND through the wiring A3, the outward electrode A2, the current probe Pc2, the switch 62 and the constant current source CS2 is formed .

The voltage detection unit 4 measures the voltage between the detection probes Pv1 and Pv2. The voltage detecting section 4 is configured by using, for example, an analog-digital converter or a voltage-dividing resistor. The positive terminal of the voltage detector 4 is connected to the detection probe Pv1 via the switch 63 and the negative terminal of the voltage detector 4 is connected to the detection probe Pv2. The voltage detector 4 measures the voltage between the detection probes Pv1 and Pv2 selected by the scanner 6 as the measurement voltage Vs and outputs data indicating the measured voltage Vs to the controller 5 do.

The control unit 5 includes, for example, a CPU (Central Processing Unit) for executing predetermined arithmetic processing, a RAM (Random Access Memory) for temporarily storing data, a nonvolatile storage unit , And peripheral circuits thereof, and so on. The control unit 5 functions as a resistance acquisition unit 51 and a substrate inspection unit 52 by executing a predetermined control program.

The resistance acquisition section 51 calculates the resistance value Rx of the wiring A3 to be measured based on the measured voltage Vs detected by the voltage detection section 4. [ Specifically, based on the current value Is of the measuring current I = the first current value I ₁ ? The second current value I ₂ and the measured voltage Vs, ) Is used to calculate the resistance value Rx.

The resistance value (Rx) = Vs / Is ... (One)

The substrate inspecting apparatus 1 (resistance measuring apparatus) is provided with a current measuring section for measuring a current value Is of a current actually flowing in the wiring A3. The resistance obtaining section 51 has a current measuring section The resistance value Rx may be calculated using the measured current Is and the measured voltage Vs. When the current value Is is a fixed value, the resistance value Rx is proportional to the measured voltage Vs. Thus, the resistance acquisition section 51 may acquire the measurement voltage Vs as information indicating the resistance value Rx without calculating the resistance value Rx using the equation (1).

The board inspecting section 52 inspects the wiring A3 as a conductor based on the resistance value Rx acquired by the resistance acquiring section 51. [ Specifically, the substrate inspecting section 52 compares the reference value Rref stored in advance in the storage section with the resistance value Rx. When the resistance value Rx is smaller than the reference value Rref, And when the resistance value Rx is equal to or larger than the reference value Rref, it is determined that the wiring A3 is defective.

2 is an explanatory diagram showing an equivalent circuit of the substrate inspection apparatus 1 and the substrate A in a state in which the switches 61, 62, 63, 64, and 65 are turned on. 2, the resistor Rc1 represents the contact resistance between the current probe Pc1 and the chip-side electrode A1 and the resistance of the switch 61 and the resistor Rc2 represents the resistance between the current probe Pc2 and the outward electrode A2 And the resistor Rv1 indicates the resistance of the contact resistance between the detection probe Pv1 and the chip side electrode A1 and the switch 63 and the resistance Rv2 indicates the resistance of the switch 63. [ The contact resistance between the detection probe Pv2 and the outward electrode A2 and the resistance such as the switch 64 and the resistance RG indicates the contact resistance between the grounding probe PG and the outward electrode A2, Respectively. The parasitic capacitance generated in the equivalent circuit shown in Fig. 2 is represented by the capacitor Cp.

Hereinafter, the operation of the substrate inspection apparatus 1 will be described based on the equivalent circuit shown in Fig. First, a constant current source (CS1) result to the first output current of the current value (I _1), and a constant current source (CS2), the output current of the second current value (I _2), wiring (A3) has a current value A current (I) for measurement of the current Is flows. At this time, the voltage of the normal mode generated in the wiring A3 is detected by the voltage detecting unit 4 through the detection probes Pv1 and Pv2 different from the current probes Pc1 and Pc2 through which the measuring current I flows, (Vs), and the measured voltage (Vs) is transmitted from the voltage detecting section (4) to the resistance obtaining section (51).

In this case, since no current flows through the resistors Rv1 and Rv2, the resistance value Rx is acquired based on the measured voltage Vs excluding the resistors Rv1 and Rv2 by the resistance acquisition unit 51 , It is possible to perform resistance measurement with high accuracy in comparison with the so-called two-terminal measuring method.

Next, the common mode voltage will be described. A constant current source (CS2) and the resistor (Rc2) are so connected in series, and going a current of a second current value (I ₂₎ flows, first in the first resistor (Rc2). When the resistance of the resistor (Rc2) a resistance value Rc _2, the voltage of Rc ₂ × I ₂ occurs at the resistor (Rc2). Since the internal resistance of the constant current circuit is generally high impedance and the negative (-) potential of the constant current power source CS2 does not coincide with the ground potential, the voltage generated in the resistor Rc2 is not directly applied to the resistor RG . However, at least a portion of the voltage generated at the resistor (Rc2) is applied to the resistor (RG), and the current going to the current value (I ₃₎ to the resistor (RG) flows.

Here, between the first current value I ₁ , the second current value I ₂ , and the current value I ₃ , there is a relationship expressed by the following equations (2) and (3).

I ₁ = I ₂ + I ₃ ... (2)

I ₁ ? I ₂ ... (3)

Here, the constant current source (CS1) is a constant current source, so from the first current value (I ₁₎ is a constant value, and the first current value (I ₁₎ ≒ second current value (I ₂₎ so, for measuring the current (I) When the current classification of the current value (I ₃₎ to the resistor (RG), the negative electrode of the constant current source (CS2) (-) is the current supplied to the shortage relative to the second current value (I _2), the constant current source (CS2) The current of the second current value I ₂ can not flow.

Here, because the constant current source (CS2) is also a constant current source to flow to try to force the second current value (I _2). At this time, the constant current source (CS2), the positive electrode (+) is so connected to the ground, a constant current source (CS2), the second current value by the action of trying to forcibly flow in the (I _2), the constant current source (CS2) of The negative (-) potential of the constant current source CS2 drops until the current of the second current value I ₂ is supplied to the negative electrode (-). The negative electrode of the constant current source (CS2) (-) the second current value with respect to the (I ₂₎ from (≒ first current value (I ₁₎₎ is the state in which current is applied, the formula (2), the current value (I ₃ ) &Amp;efDot;

It is the current value (I ₃₎ ≒ 0 through resistor (RG), means that the potential at the two ends of the resistor (RG) become approximately equal. Since one end of the resistor RG is connected to the ground, the other end of the resistor RG, that is, the potential of the outward electrode A2 shown in Fig. 2, becomes a substantially ground potential. Since the detection probe Pv2 is in contact with the outward electrode A2, the potential of the outward electrode A2 becomes substantially equal to the ground potential because the common mode voltage applied to the voltage detection portion 4 is approximately zero .

As described above, are connected in series, and a constant current source (CS1) and the constant current source (CS2) is the connection point A to the ground potential, respectively, the first current value (I _1), the second output of the current value (I ₂₎ As a result of attempting to maintain the current, the above-described operation is carried out within a moment of time corresponding to the response time of the constant current sources CS1 and CS2, and the common mode voltage becomes substantially zero.

As described above, in the background art, measurement accuracy of measurement voltage is affected by fluctuation of common mode voltage. On the other hand, since the substrate inspection apparatus 1 can make the common mode voltage approximately zero, it is possible to improve the measurement accuracy of the resistance value Rx to be measured in comparison with the background technology. Therefore, it is easy to improve resistance measurement accuracy by the four-terminal measuring method.

3 is a flowchart showing an example of a resistance measuring method according to an embodiment of the present invention. First, the resistance acquisition section 51 moves the current probe Pc1 and the detection probe Pv1 by a driving mechanism (not shown) to make contact with the chip-side electrode A1 (step S1: step (a) . Next, the resistance acquisition section 51 moves the current probe Pc2, the detection probe Pv2, and the grounding probe PG by a drive mechanism (not shown) to make contact with the outward electrode A2 Step S2: Steps (b) and (d)).

Next, the resistance acquisition section 51 turns on the switches 61, 62, 63, 64, and 65 (step S3). Steps S2 and S3 correspond to an example of step (d). Next, the resistance acquisition unit 51, the first current value by a constant current source (CS1) (I ₁₎ (= Is), the second current value and outputting a current, by a constant current source (CS2) of (I ₂ ) (? I ₁ ) (step S4: step (c)).

Next, the voltage detecting section 4 measures the voltage between the detecting probes Pv1 and Pv2 as the measuring voltage Vs (step S5: step (e)). Next, the resistance acquisition section 51 calculates the resistance value Rx of the measurement object based on the equation (1) (step S6), and sets the resistance value Rx to, for example, To be displayed by the device.

As described above, since the resistance value Rx can be calculated based on the measured voltage Vs measured in the state where the common mode voltage is made substantially zero by the processing of the steps S1 to S6, the calculation accuracy of the resistance value Rx Can be easily improved. Therefore, it is easy to improve resistance measurement accuracy by the four-terminal measuring method.

Next, the substrate inspection section 52 compares the resistance value Rx with the reference value Rref (step S7). If the resistance value Rx is less than the reference value Rref (YES in step S7), the board inspecting section 52 judges that the wiring A3 is good (step S8). On the other hand, if the resistance value Rx is equal to or larger than the reference value Rref (NO in step S7), the substrate inspection section 52 determines that the wiring A3 is defective (step S9) The display is indicated by the omitted display, and the processing is terminated.

The resistance value Rx of all the wirings A3 to be measured on the substrate A can be measured for the other wirings A3 by repeating the same processing as the steps S1 to S9, It is possible to check whether or not this is a good product.

In addition, since the common mode voltage is noise, setting the common mode voltage to approximately zero corresponds to improving the S / N ratio of the measured voltage Vs. Therefore, according to the substrate inspecting apparatus 1 and the resistance measuring method described above, it is possible to improve the S / N ratio and improve the measurement accuracy of the resistance value Rx based on the measured voltage Vs.

As a method for improving the S / N ratio of the measured voltage Vs, it is conceivable to increase the current value of the measuring current to increase the measured voltage as the signal component. However, when the current value of the measurement current is increased in the circuit of FIG. 1 of Patent Document 1, the voltage generated by the contact resistance between the contact probe P2 on the negative electrode side and the measurement object M is increased. As a result, The voltage is increased. Therefore, in the circuit described in Fig. 1 of Patent Document 1, it is not easy to improve the S / N ratio.

On the other hand, according to the substrate inspecting apparatus 1, since the S / N ratio of the measured voltage Vs can be improved by reducing the common mode voltage to substantially zero, the S / N ratio is improved, .

In the circuit described in Fig. 1 of Patent Document 1, when resistance measurement is performed on a measurement object such as a component-embedded board or an electronic component, if a common mode voltage is generated during measurement, There is a case where a potential difference is generated between the measurement object and the substrate inspecting apparatus due to the charge charge of the parasitic capacitance of the object to be measured. In such a case, due to the potential difference, voltage or current stress is applied to the electronic part, which may damage the electronic part.

4 shows a connection of the substrate inspection apparatus 1 when inspecting an IC (Integrated Circuit) 100 having signal terminals P1 to Pn, a power supply terminal Vcc and a ground terminal GND Fig. As described above, in the resistance measurement by the conventional two-terminal method or the four-terminal method without using the two constant current sources CS1 and CS2 and the grounding probe PG, the current probes Pc1 and Pc2, (Pv1, Pv2) are brought into contact with the common mode voltage. The common mode voltage added to the terminal of the IC returns to the parasitic capacitance Co and the IC 100 is supplied with the parasitic capacitance Co generated by the IC 100 itself or external wiring, Stress was applied, or breakage occurred.

In this case, by slowly increasing the common mode voltage by gradually increasing the measuring current, the parasitic capacitance is gradually charged to the common mode voltage, thereby reducing the value of the current flowing into the parasitic capacitance, Can be considered. Thus, it is considered that the damage of the electronic component can be prevented. However, in the method of slowly charging the parasitic capacitance by gradually increasing the measuring current, it is necessary to wait for the voltage measurement until the parasitic capacitance of the measurement object becomes charged by the common mode voltage and the potential difference disappears, do.

However, according to the substrate inspection apparatus 1, since the common mode voltage becomes substantially zero, there is no need to wait for the voltage measurement until the parasitic capacitance of the measurement object is charged to the common mode voltage and the potential difference disappears. As a result, it is easy to shorten the resistance measurement time and inspection time.

As a method of setting the common mode voltage to zero, as described in Japanese Patent Application Laid-Open No. 2007-333598 (Patent Document 2), by feeding back the common mode voltage to the inverting amplifier circuit of the operational amplifier, And the common mode voltage is canceled by the output. However, in such a method, the feedback delay time due to the resistance component of the feedback circuit and the parasitic capacitance, the response delay of the operational amplifier, and the like occur, so that it is not easy to cancel the unstable common mode voltage.

On the other hand, in the substrate inspection device (1), are connected in series, and each of the constant current source (CS1) and the constant current source (CS2) connection point a to the ground potential first current value (I _1), the second current value result, the common mode voltage is approximately zero, which tries to keep the output current (I _2), it is easy to reduce the common mode voltage.

The substrate inspecting apparatus 1 may be a resistance measuring apparatus without the substrate inspecting unit 52, and steps S7 to S9 may not be executed. In addition, the scanner 6 may not be provided. The grounding probe PG is not limited to the example in which the grounding probe PG is necessarily brought into contact with one end of the negative electrode of the outward electrode A2, that is, the wiring A3 (conductor). The grounding probe PG may be in contact with the chip-side electrode A1 which is one end on the positive side of the wiring A3, or may be in contact with the chip-side electrode A1 on the negative side of the wiring A3, .

It should be noted that the current probes Pc1 and Pc2 and the detection probes Pv1 and Pv2 are not necessarily limited to the examples in which they are contacted at both ends of the wiring A3 (conductor) to be measured. Even if the current probes Pc1 and Pc2 and the detection probes Pv1 and Pv2 are brought into contact with the middle portion of the object to be measured, the contact points of the current probe Pc1 and the detection probe Pv1, the current probe Pc2, The resistance value between the contact points of the first and second electrodes Pv2 can be measured.

(Second Embodiment)

Next, the substrate inspection apparatus 1a using the resistance measuring apparatus according to the second embodiment of the present invention will be described. 5 is a block diagram showing an example of the configuration of the substrate inspection apparatus 1a using the resistance measuring apparatus according to the second embodiment of the present invention. 6 is an explanatory view showing an equivalent circuit of the substrate inspection apparatus 1a and the substrate A shown in Fig. The substrate inspection apparatus 1a shown in Figs. 5 and 6 and the substrate inspection apparatus 1 shown in Fig. 1 are different from the following points.

That is, the substrate inspection apparatus 1a shown in Figs. 5 and 6 does not include the grounding probe PG and the switch 65, and instead the negative (-) terminal of the voltage detecting unit 4 is connected to the ground The substrate inspection apparatus 1 is different from the substrate inspection apparatus 1 in that In this case, the wiring connecting the negative (-) terminal of the voltage detecting section 4 to the ground corresponds to an example of the grounding section. In addition, in step S2, the grounding probe PG is not brought into contact with the outward electrode A2, and the switch 65 is not turned on in step S3.

Other configurations are the same as those of the substrate inspecting apparatus 1 shown in Fig. 1, and a description thereof will be omitted. The substrate inspecting apparatus 1a also has a constant current source CS1 and a constant current source CS2 which are connected in series and whose connection points are at ground potential, To maintain the output current of the value (I ₁ ) and the second current value (I ₂ ). As a result, the current value (I ₃₎ flowing through the resistor (Rv2) is approximately zero, since the common mode voltage is substantially zero, it is easy to reduce the common mode voltage.

Further, according to the substrate inspection apparatus 1a, it is not necessary to separately form the grounding probe PG, so that it is easier to reduce the cost than the substrate inspection apparatus 1. Further, since the number of probes to be brought into contact with the wiring A3 may be two, it is easier to contact the probes than the substrate testing apparatus 1 which requires contacting three probes with the wiring A3.

However, the manufacturing variation of a constant current source for the first current value (I ₁₎ and the second current value (I ₂₎ are substantially the same (I ₁ ≒ I _2), but, the constant current source (CS1, CS2) of (CS1, CS2) Or there may be a slight difference due to the current control precision. When a difference is generated between the first current value I ₁ and the second current value I ₂ , the current of the current value I ₃ corresponding to the difference flows through the resistor Rv 2 shown in FIG. In this case, when the resistance of the resistor (Rv2) a resistance value Rv _2, a voltage of ₂ × Rv I ₃ is generated at the resistor (Rv2). Since this voltage is included in the measured voltage Vs measured by the voltage detecting section 4, a measurement error of the measured voltage Vs is generated.

On the other hand, in the substrate inspection device 1 shown in Figure 2, the first current value (I ₁₎ and the second current value (I ₂₎ when the difference occurs between, a current of a current value (I ₃₎ corresponding to the difference Flows through the resistor RG. The voltage generated by the current flowing through the resistor RG is not included in the measured voltage Vs in the substrate inspection apparatus 1. [ Therefore, the substrate inspection apparatus 1 is advantageous in that a measurement accuracy error caused by a difference between the first current value I ₁ and the second current value I ₂ is less likely to occur than the substrate inspection apparatus 1a , More preferable.

1: Substrate inspection device (resistance measurement device)
4: Voltage detector
5:
6: Scanner
51:
52:
61, 62, 63, 64, 65: switch
A: substrate
A1: chip side electrode (first electrode)
A2: outward electrode (second electrode)
A3: Wiring (conductor)
Cp: Capacitor
CS1: constant current source (first constant current source)
CS2: constant current source (second constant current source)
GND: Ground
I: Current for measurement
I ₁ : first current value
I ₂ : second current value
Is, I ₃ : current value
Pc1: current probe (first current probe)
Pc2: Current probe (second current probe)
PG: Grounding probe (ground)
Pv1: detection probe (first detection probe)
Pv2: detection probe (second detection probe)
Pc1, Pc2, Pv1, Pv2, PG: Probe
Rc1, Rc2, Rv1, Rv2, RG: Resistance
Rc ₂ , Rv ₂ , Rx: resistance value
Rref: Reference value
Vs: Measured voltage

Claims (8)

A resistance measuring apparatus for measuring a resistance of a conductor,
First and second current probes for bringing a predetermined measurement current into contact with the conductor,
First and second detection probes for contacting the conductor to detect a voltage generated in the conductor by the measuring current,
A voltage detector for detecting a voltage between the first and second detection probes,
A first constant current source having a positive electrode connected to the first current probe, a negative electrode connected to the ground, and outputting a predetermined first current value,
Wherein a positive electrode is connected to the negative electrode of the first constant current source and the ground and is connected in series with the first constant current source, the negative electrode is connected to the second current probe, and a second current value A second constant current source for outputting a current,
A grounding portion for conducting a predetermined portion of the conductor to the ground,
And a resistance acquisition section that acquires the resistance based on the voltage detected by the voltage detection section. The method according to claim 1,
Wherein the grounding portion includes a grounding probe for contacting the predetermined portion,
And the grounding probe is connected to the ground. The method according to claim 1,
The ground unit may include:
And connecting the second detection probe to the ground. A resistance measuring apparatus according to any one of claims 1 to 3,
And a board inspecting unit that inspects the wiring that is the conductor formed on the board based on the resistance measured by the resistance measuring apparatus. A resistance measuring method for measuring a resistance of a conductor,
(a) contacting the first current probe and the first detection probe to the conductor,
(b) bringing the second current probe and the second detection probe into contact with each other at a position separated from a contact position of the first current probe and the first detection probe of the conductor,
(c) a positive electrode connected to the first current probe, a negative electrode connected to the ground and configured to output a current of a first current value preset by the first constant current source, and a positive electrode connected to the negative electrode of the first constant current source and the ground Outputting a current of a second current value substantially equal to the first current value by a second constant current source connected in series with the first constant current source and having a negative electrode connected to the second current probe;
(d) conducting a predetermined portion of the conductor with the ground,
(e) detecting a voltage between the first and second detection probes,
(f) obtaining the resistance based on the voltage detected by the step (e). 6. The method of claim 5,
Wherein the step (d) is a step of bringing the ground probe connected to the ground into contact with the predetermined portion. 6. The method of claim 5,
The second detection probe is connected to the ground,
The step (b) also serves as the step (d). The method according to claim 6,
A first electrode is formed on one end of the conductor and a second electrode is formed on the other end of the conductor with a larger area than the first electrode,
The step (a) is a step of bringing the first current probe and the first detection probe into contact with the first electrode,
The step (b) is a step of bringing the second current probe and the second detection probe into contact with the second electrode,
Wherein the step (d) comprises bringing the ground probe into contact with the second electrode with the second electrode as the predetermined portion.

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