JP6765125B2 - Resistance measuring device, substrate inspection device, and resistance measuring method - Google Patents

Description

The present invention relates to a resistance measuring device for measuring resistance, a substrate inspection device using the resistance measuring device, and a resistance measuring method.

Conventionally, in order to inspect a wiring pattern formed on a substrate such as a printed wiring board, the resistance value of the wiring pattern has been measured. As the inspection of the wiring pattern, it is necessary not only to inspect the presence or absence of disconnection, but also to detect defects that do not lead to disconnection, such as the width of the wiring pattern becoming narrower or the thickness becoming thinner. In order to detect such a defect that does not lead to disconnection, it is necessary to perform resistance measurement with high accuracy. As such a highly accurate resistance measuring method, a resistance measuring device using a four-terminal measuring method is known (see, for example, Patent Document 1).

The resistance measuring device described in Patent Document 1 includes a pair of contact probes P1 and P2 for passing a current for resistance measurement through a wiring pattern to be measured for resistance, and a pair of contact probes for measuring a voltage at a resistance measuring point. It has P3 and P4.

According to the resistance measuring device 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 themselves is reduced and the accuracy is high. Resistance measurement is possible. In the resistance measuring device described in Patent Document 1, the contact probe P1 on the positive electrode side for current output is connected to a constant current source, and the contact probe P2 on the negative electrode side is connected to the circuit ground (FIG. 1 of Patent Document 1). 1).

Japanese Unexamined Patent Publication No. 2004-184374 JP-A-2007-333598

However, in the resistance measuring device described in Patent Document 1, a current for resistance measurement flows through the contact resistance between the contact probe P2 on the negative electrode side and the measurement target body M to generate a voltage. This voltage becomes a common mode voltage (common mode noise) with respect to the contact probes P3 and P4 for voltage measurement. Since the contact resistance Ro of the contact probe P2 can be about 100Ω, if the current i for resistance measurement is 20mA, the common mode voltage Vc is Ro × i = 100Ω × 20mA = 2000mV (see FIG. 7).

On the other hand, for example, when the measurement target is a wiring pattern, the 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 mAΩ × 20 mA = 20 μV = 0.02 mV (see FIG. 7).

Then, the measured voltage becomes 20 log (measured voltage / common mode voltage) = 20 log (0.02 / 2000) = −100 dB with respect to 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 unstable. Since the measured voltage is a minute voltage of about -100 dB with respect to the common mode voltage, the measured voltage is affected by the fluctuation of the common mode voltage and its measurement accuracy is lowered. As a result, there is a disadvantage that the accuracy of the resistance measurement value obtained based on the measured voltage is also lowered.

Further, as a method of setting the common mode voltage to zero, as described in Patent Document 2, a method of canceling the common mode voltage at the output of the operational amplifier by feeding back the common mode voltage to the inverting amplifier circuit of the operational amplifier. Can be considered. FIG. 8 is an equivalent circuit diagram of the circuit described in FIG. 1 of Patent Document 2. The contact resistance and the like of the current supply terminals 22 and 23 and the voltage measurement terminals 24 and 25 of Patent Document 2 are indicated by Ro, and the parasitic capacitance is indicated by Co.

However, in such a method, a feedback time delay due to Ro which is a resistance component of the feedback circuit and a parasitic capacitance Co, a response delay of the operational amplifier, etc. occur, so that high-speed operation is difficult and a common mode voltage which fluctuates unstable is generated. Not easy to cancel.

An object of the present invention is to provide a resistance measuring device, a substrate inspection device, and a resistance measuring method that can easily improve the resistance measurement accuracy by the four-terminal measuring method.

The resistance measuring device according to the present invention is a resistance measuring device for measuring the resistance of a conductor, and is a first and second current probe for contacting the conductor and passing a predetermined measuring current, and the conductor. The first and second detection probes for detecting the voltage generated in the conductor by the measurement current, the voltage detection unit for detecting the voltage between the first and second detection probes, and the positive electrode A first constant current source that is connected to the first current probe, the negative voltage is connected to the ground, and outputs a current of a preset first current value, and a positive voltage is connected to the negative voltage and the ground of the first constant current source. A second constant current that is connected and connected in series with the first constant current source, the negative voltage is connected to the second current probe, and outputs a current with a second current value that is substantially the same as the first current value. It includes a source, a grounding portion that conducts a predetermined portion of the conductor with the ground, and a resistance acquiring portion that acquires the resistance based on the voltage detected by the voltage detecting unit.

Further, the resistance measuring method according to the present invention is a resistance measuring method for measuring the resistance of a conductor, which includes (a) a step of bringing the first current probe and the first detection probe into contact with the conductor, and (b). A step of bringing the second current probe into contact with the second detection probe at a position of the conductor separated from the contact positions of the first current probe and the first detection probe, and (c) the positive electrode is the first current. A current of a first current value set in advance by a first constant current source connected to a probe and connected to the ground is output, and a positive electrode is connected to the negative electrode and the ground of the first constant current source. A step of outputting a current having a second current value substantially the same as the first current value by a second constant current source connected in series with the first constant current source and having the negative electrode connected to the second current probe. , (D) The step of conducting a predetermined portion of the conductor with the ground, (e) the step of detecting the voltage between the first and second detection probes, and (f) the step of (e). The step of acquiring the resistance based on the voltage is included.

According to these configurations, it is possible to perform resistance measurement by a four-terminal measurement method using the first and second current probes and the first and second detection probes. Then, as a result, the first constant current source and the second constant current source, which are connected in series and whose connection point is set to the ground potential, try to maintain the output currents of the first current value and the second current value, respectively. , The current flowing from a predetermined part of the conductor conducted to the ground to the ground becomes almost zero. As a result, the common mode voltage becomes almost zero. Then, since the resistance can be acquired based on the measured voltage measured with the common mode voltage set to substantially zero, it becomes easy to improve the measurement accuracy of the resistance. Therefore, it becomes easy to improve the resistance measurement accuracy by the four-terminal measurement method.

Further, it is preferable that the grounding portion includes a grounding probe for contacting the predetermined portion, and the grounding probe is connected to the ground.

Further, the step (d) is preferably a step of bringing the grounding probe connected to the ground into contact with the predetermined portion.

According to these configurations, the conductor can be made conductive with the ground by bringing the grounding probe into contact with a predetermined portion of the conductor.

Further, the grounding portion may be a wiring for connecting the second detection probe to the ground.

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

According to these configurations, the second detection probe can also be used as a grounding probe, so that it is not necessary to separately provide a grounding probe and bring it into contact with the conductor.

Further, a first electrode is provided at one end of the conductor, a second electrode having a larger area than the first electrode is provided at the other end of the conductor, and the step (a) is performed on the first electrode. Is a step of bringing the first current probe into contact with the first detection probe, and the step (b) is a step of bringing the second current probe and the second detection probe into contact with the second electrode. The step (d) is preferably a step of bringing the grounding probe into contact with the second electrode with the second electrode as the predetermined portion.

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

Further, the substrate inspection apparatus according to the present invention includes the above-mentioned resistance measuring apparatus and a substrate inspection unit for inspecting the wiring which is the conductor formed on the substrate based on the resistance measured by the resistance measuring apparatus. Be prepared.

According to this configuration, it is possible to inspect the wiring formed on the substrate based on the resistance measured by the resistance measuring device.

The resistance measuring device, the substrate inspection device, and the resistance measuring method having such a configuration make it easy to improve the resistance measuring accuracy by the four-terminal measuring method.

It is a block diagram which shows an example of the structure of the substrate inspection apparatus using the resistance measuring apparatus which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the board inspection apparatus shown in FIG. 1 and the equivalent circuit of a board. It is a flowchart which shows an example of the resistance measurement method which concerns on one Embodiment of this invention. It is explanatory drawing which showed the connection of the substrate inspection apparatus at the time of inspecting an IC. It is a block diagram which shows an example of the structure of the substrate inspection apparatus using the resistance measuring apparatus which concerns on 2nd Embodiment of this invention. It is explanatory drawing which shows the board inspection apparatus shown in FIG. 5 and the equivalent circuit of a board. It is explanatory drawing for demonstrating the common mode voltage which concerns on background art. It is an equivalent circuit diagram of the circuit described in FIG. 1 of Patent Document 2.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
(First Embodiment)

FIG. 1 is a block diagram showing an example of the configuration of a substrate inspection device 1 using the resistance measuring device according to the first embodiment of the present invention. It should be noted that the configurations with the same reference numerals in each figure indicate that they are the same configurations, and the description thereof will be omitted.

The substrate inspection device 1 (resistance measuring device) shown in FIG. 1 includes a constant current source CS1 (first constant current source), a constant current source CS2 (second constant current source), a voltage detection unit 4, and a current probe Pc1 (first). Current probe), current probe Pc2 (second current probe), detection probe Pv1 (first detection probe), detection probe Pv2 (second detection probe), grounding probe PG (grounding part), scanner 6, and control unit 5. I have.

FIG. 1 shows a state in which each probe of the substrate inspection device 1 is in contact with the substrate A to be inspected. The substrate inspection device 1 is adapted to measure resistance by a so-called four-terminal measuring method. The portion excluding the substrate inspection unit 52, which will be described later, from the substrate inspection apparatus 1 corresponds to an example of the resistance measuring apparatus.

The substrate to be inspected may be, for example, 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 board, or the like, and a liquid crystal display or EL (Electro). -Luminescence) It may be an electrode plate for a display such as a display, a transparent conductive plate for a touch panel, or various substrates such as a semiconductor wafer, a semiconductor chip, or a semiconductor substrate such as a CSP (Chip size package). Good.

Further, the substrate to be inspected may be a component-embedded substrate (embedded substrate) in which electronic components such as semiconductor chips are embedded. Further, the inspection target is not limited to the substrate, and may be an electronic component such as a semiconductor chip. Inspection points such as wiring patterns, pads, lands, solder bumps, and terminals are formed on the substrate and electronic components to be inspected.

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

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

Each chip-side electrode A1 and each outward electrode A2 are electrically connected by a wiring A3 (conductor) formed so as to penetrate the thickness direction of the substrate A. The board inspection device 1 measures and inspects the resistance value Rx of each wiring A3. The wiring A3 corresponds to an example of a conductor, the chip side electrode A1 corresponds to one end of the wiring A3, and the outward electrode A2 corresponds to the other end of the wiring A3.

The current probes Pc1, Pc2, the detection probes Pv1, Pv2, and the grounding probe PG are configured as inspection jigs that can be attached to and detached from, for example, the substrate inspection device 1. Hereinafter, the current probes Pc1, Pc2, the detection probes Pv1, Pv2, and the grounding probe PG may be simply referred to as probes Pc1, Pc2, Pv1, Pv2, PG.

The probes Pc1, Pc2, Pv1, Pv2, PG are wire-shaped contacts having elasticity (flexibility) having a diameter of, for example, about 100 μm to 200 μm. The current probes Pc1 and Pc2 and the detection probes Pv1 and Pv2 are made 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 tips 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. If each probe is brought into contact with the chip-side electrode A1 and the outward electrode A2 in this way, two probes are brought into contact with the small and narrow-pitch chip-side electrode A1 and are larger than the chip-side electrode A1. In addition, three probes are brought into contact with the wide-pitch outward electrode A2. Therefore, it becomes easy to bring each probe into contact with the chip side electrode A1 and the outward electrode A2.

In FIG. 1, the probes Pc1, Pc2, Pv1, Pv2, and PG are shown one by one for simplification of the illustration, but there are cases where hundreds to thousands of inspection points are set for one substrate. There are cases where hundreds to thousands of probes Pc1, Pc2, Pv1, Pv2, PG are provided corresponding to such a large number of inspection points.

The scanner 6 has a connection relationship between these current probes Pc1 and Pc2 and constant current sources CS1 and CS2, a connection relationship between these detection probes Pv1 and Pv2 and a voltage detection unit 4, and a grounding probe PG and ground. It is a switching circuit that switches the connection relationship. The scanner 6 includes a plurality of switches including, for example, switches 61, 62, 63, 64, 65. Switches such as switches 61, 62, 63, 64, 65 are various switching elements such as semiconductor switches such as transistors and relay switches. Each switch is turned on and off according to, for example, a control signal from the control unit 5.

The constant current sources CS1 and CS2 are constant current circuits through which a constant current flows, and a constant current for measurement is passed through the wiring A3. As the constant current sources CS1 and CS2, various circuits known as constant current circuits such as those using transistors and Zener diodes and those using current mirror circuits can be used, or switching power supply circuits and the like are used. It may be configured.

The positive electrode (+) of the constant current source CS1 is connected to the current probe Pc1 via the switch 61, and the negative electrode (−) is connected to the ground GND. The constant current source CS1 outputs a current having a preset first current value I ₁ from its positive electrode (+) to the current probe Pc1. The first current value I ₁ is, for example, about 20 mA.

The positive electrode (+) of the constant current source CS2 is connected to the negative electrode (-) and the ground GND of the constant current source CS1 and connected in series with the constant current source CS1, and the negative electrode (-) is connected to the current probe via the switch 62. It is connected to Pc2. The constant current source CS2 outputs a current having a second current value I ₂ which is substantially the same as the first current value I ₁ from its positive electrode (+) to the constant current source CS1. Here, substantially the same means that even if there is a difference in the degree of difference caused by manufacturing variations of the constant current sources CS1 and CS2, current control accuracy, etc., they are regarded as the same.

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

When the switches 61, 62, 63, 64, 65 are turned on by the control unit 5, the constant current source CS1, the switch 61, the current probe Pc1, the chip side electrode A1, the wiring A3, the outward electrode A2, and the current probe are transmitted from the ground GND. A current loop of measurement current I returning to the ground GND is formed via the Pc2, the switch 62, and the constant current source CS2.

The voltage detection unit 4 measures the voltage between the detection probes Pv1 and Pv2. The voltage detection unit 4 is configured by using, for example, an analog digital converter, a voltage dividing resistor, or the like. The positive electrode side (+) terminal of the voltage detection unit 4 is connected to the detection probe Pv1 via the switch 63, and the negative electrode side (−) terminal of the voltage detection unit 4 is connected to the detection probe Pv2 via the switch 64. As a result, the voltage detection unit 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 measurement voltage Vs to the control unit 5.

The control unit 5 includes, for example, a CPU (Central Processing Unit) that executes predetermined arithmetic processing, a RAM (Random Access Memory) that temporarily stores data, a non-volatile storage device that stores a predetermined control program, and the like. It is a so-called microcomputer equipped with these peripheral circuits and the like. 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 unit 51 calculates the resistance value Rx of the wiring A3 to be measured based on the measured voltage Vs detected by the voltage detection unit 4. Specifically, the resistance value Rx is calculated using the following equation (1) based on the current value Is of the measurement current I = the first current value I ₁ ≒ the second current value I ₂ and the measurement voltage Vs. To do.
Resistance value Rx = Vs / Is ... (1)

The substrate inspection device 1 (resistance measuring device) includes a current measuring unit that measures the current value Is of the current actually flowing through the wiring A3, and the resistance acquiring unit 51 has the current value Is measured by the current measuring unit. The resistance value Rx may be calculated using the measured voltage Vs. If the current value Is is a fixed value, the resistance value Rx is proportional to the measured voltage Vs. Therefore, the resistance acquisition unit 51 may acquire the measured voltage Vs as information representing the resistance value Rx as it is, without calculating the resistance value Rx using the equation (1).

The substrate inspection unit 52 inspects the wiring A3, which is a conductor, based on the resistance value Rx acquired by the resistance acquisition unit 51. Specifically, the substrate inspection unit 52 compares the reference value Rref stored in the storage unit in advance with the resistance value Rx, and if the resistance value Rx is smaller than the reference value Rref, determines that the wiring A3 is a good product. If the resistance value Rx is equal to or greater than the reference value Rref, the wiring A3 is determined to be defective.

FIG. 2 is an explanatory diagram showing an equivalent circuit of the substrate inspection device 1 and the substrate A in a state where the switches 61, 62, 63, 64, and 65 are turned on. In FIG. 2, the resistor Rc1 shows the contact resistance between the current probe Pc1 and the chip side electrode A1 and the resistance of the switch 61 and the like, and the resistor Rc2 shows the contact resistance between the current probe Pc2 and the outward electrode A2 and the resistance of the switch 62 and the like. The resistor Rv1 indicates the contact resistance between the detection probe Pv1 and the chip side electrode A1 and the resistance of the switch 63, etc., and the resistor Rv2 indicates the contact resistance between the detection probe Pv2 and the outward electrode A2 and the resistance of the switch 64, etc. Indicates the contact resistance between the ground probe PG and the outward electrode A2 and the resistance of the switch 65 or the like. Further, the parasitic capacitance generated in the equivalent circuit shown in FIG. 2 is shown by the capacitor Cp.

Hereinafter, the operation of the substrate inspection device 1 will be described based on the equivalent circuit shown in FIG. First, the constant current source CS1 outputs the current having the first current value I ₁ , and the constant current source CS2 outputs the current having the second current value I _2. As a result, the wiring A3 has the current I for measuring the current value Is. It flows. At this time, the voltage in the normal mode generated in the wiring A3 is measured as the measured voltage Vs by the voltage detection unit 4 via the detection probes Pv1 and Pv2 different from the current probes Pc1 and Pc2 through which the measurement current I flows. The measurement voltage Vs is transmitted from the detection unit 4 to the resistance acquisition unit 51.

In this case, since no current flows through the resistors Rv1 and Rv2, the resistance acquisition unit 51 acquires the resistance value Rx based on the measured voltage Vs from which the resistors Rv1 and Rv2 are excluded, resulting in a so-called two-terminal measurement method. Compared to this, resistance measurement can be performed with high accuracy.

Next, the common mode voltage will be described. Since the constant current source CS2 and the resistor Rc2 are connected in series, the current of the second current value I ₂ tries to flow through the resistor Rc2 first. When the resistance value of the resistor Rc2 and the resistance value Rc _2, the voltage of Rc ₂ × _{I 2} occurs in the resistor Rc2. In a constant current circuit, the internal resistance is generally high impedance, and the negative electrode (−) potential of the constant current power supply CS2 does not match the ground potential. Therefore, the voltage generated by the resistor Rc2 is not directly applied to the resistor RG. However, at least a portion of the voltage developed by resistor Rc2 is applied to the resistor RG, a current of a current value I ₃ in the resistor RG is going to flow.

Here, the first current value I ₁ , the second current value I ₂ , and the current value I _{3 have} a relationship represented by the following equations (2) and (3).

I ₁ = I ₂ + I ₃ ... (2)

I ₁ ≒ I ₂ ... (3)

Here, since the constant current source CS1 is a constant current source, the first current value I ₁ is a constant value, and the first current value I ₁ ≈ the second current value I ₂ , so the resistance from the measurement current I When the current of the current value I ₃ is diverted to the RG, the current supplied to the negative electrode (-) of the constant current source CS2 is insufficient with respect to the second current value I ₂ , and the constant current source CS 2 has the second current value I ₂ It becomes impossible to pass the current.

Here, since the constant current source CS2 is also a constant current source, the second current value I ₂ is forced to flow. At this time, since the positive electrode (+) of the constant current source CS2 is connected to the ground, the negative electrode of the constant current source CS2 (due to the action of the constant current source CS2 forcibly flowing the second current value I ₂ ). The negative electrode (−) potential of the constant current source CS2 decreases until a current having a second current value I ₂ is supplied with respect to −). The state in which the current of the second current value I ₂ (≈first current value I ₁ ) is supplied to the negative electrode (-) of the constant current source CS2 is the current value I ₃ ≈ 0 from the equation (2). It is in a state of becoming.

The fact that the current value I ₃ ≈ 0 flowing through the resistor RG means that the potentials at both ends of the resistor RG are substantially 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 the ground potential, which means that the common mode voltage applied to the voltage detection unit 4 becomes substantially zero. It is nothing but.

As described above, the constant current source CS1 and the constant current source CS2, which are connected in series and whose connection points are set to the ground potential, generate output currents of the first current value I ₁ and the second current value I ₂ , respectively. As a result of trying to maintain, the above-mentioned operation is performed within a momentary time of about 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 technology, the measurement accuracy of the measured voltage is lowered due to the influence of the fluctuation of the common mode voltage. On the other hand, since the substrate inspection device 1 can make the common mode voltage substantially zero, it is possible to improve the measurement accuracy of the resistance value Rx to be measured as compared with the background technology. Therefore, it is easy to improve the resistance measurement accuracy by the four-terminal measurement method.

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

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

Next, the voltage detection unit 4 measures the voltage between the detection probes Pv1 and Pv2 as the measurement voltage Vs (step S5: step (e)). Next, the resistance acquisition unit 51 calculates the resistance value Rx to be measured based on the equation (1) (step S6), and displays the resistance value Rx by, for example, a display device (not shown).

As described above, by the processing of steps S1 to S6, the resistance value Rx can be calculated based on the measured voltage Vs measured with the common mode voltage set to substantially zero, so that the calculation accuracy of the resistance value Rx can be improved. Becomes easier. Therefore, it is easy to improve the resistance measurement accuracy by the four-terminal measurement method.

Next, the substrate inspection unit 52 compares the resistance value Rx with the reference value Rref (step S7). Then, if the resistance value Rx does not meet the reference value Rref (YES in step S7), the board inspection unit 52 determines that the wiring A3 is good (step S8). On the other hand, if the resistance value Rx is equal to or higher than the reference value Rref (NO in step S7), the board inspection unit 52 determines that the wiring A3 is defective (step S9), and these determination results are, for example, a display device (not shown). Is displayed and the process ends.

By repeating the same process as in steps S1 to S9 for the other wirings A3, the resistance values Rx of all the wirings A3 to be measured on the substrate A can be measured, and it is inspected whether or not the substrate A is a good product. It becomes possible to do.

Further, since the common mode voltage is noise, setting the common mode voltage to substantially zero corresponds to improving the S / N ratio of the measured voltage Vs. Therefore, according to the substrate inspection device 1 and the resistance measuring method described above, the S / N ratio can be improved and the measurement accuracy of the resistance value Rx based on the measured voltage Vs can be improved.

As a method of improving the S / N ratio of the measurement voltage Vs, it is conceivable to increase the current value of the measurement current to increase the measurement voltage which is a signal component. However, when the current value of the measurement current is increased in the circuit shown in 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 increases, and as a result, the common mode voltage increases. It will increase. Therefore, it is not easy to improve the S / N ratio in the circuit described in FIG. 1 of Patent Document 1.

On the other hand, according to the substrate inspection device 1, the S / N ratio of the measured voltage Vs can be improved by setting the common mode voltage to substantially zero, so that the S / N ratio can be improved and the measurement accuracy of the resistance value Rx can be improved. Is easy to improve.

Further, in the circuit described in FIG. 1 of Patent Document 1, when resistance measurement is performed on a measurement target such as a component-embedded substrate or an electronic component, if a common mode voltage is generated during the measurement, a semiconductor element incorporated in the component-embedded substrate or the like A potential difference may occur between the measurement target and the substrate inspection device in relation to the charge charge of the parasitic capacitance of the measurement target for the electronic component. In such a case, the potential difference may apply voltage or current stress to the electronic component, resulting in damage to the electronic component.

FIG. 4 is an explanatory diagram showing a connection of a substrate inspection device 1 when inspecting an IC (Integrated Circuit) 100 including signal terminals P1 to Pn, a power supply terminal Vcc, and a ground terminal GND. As described above, in the resistance measurement by the conventional two-terminal method or four-terminal method that does not use the two constant current sources CS1 and CS2 and the grounding probe PG, the IC in which the current probes Pc1 and Pc2 and the detection probes Pv1 and Pv2 are brought into contact with each other. A common mode voltage is applied to the terminals of. Since the IC 100 has a parasitic capacitance Co generated by the IC 100 itself or external wiring, the common mode voltage applied to the terminals of the IC wraps around the parasitic capacitance Co, causing stress or damage to the IC 100. ..

In such a case, the current value flowing into the parasitic capacitance is reduced by gradually charging the parasitic capacitance with the common mode voltage by gradually increasing the measurement current and gradually increasing the common mode voltage. Moreover, it is conceivable to eliminate the potential difference between the measurement target and the substrate inspection device. It is considered that this can prevent damage to the electronic components. However, in the method of gradually increasing the measurement current to gradually charge the parasitic capacitance, it is necessary to wait for the voltage measurement until the parasitic capacitance to be measured is charged with the common mode voltage and the potential difference disappears, which is necessary for the measurement. Time increases.

However, according to the substrate inspection device 1, since the common mode voltage becomes substantially zero, it is not necessary to wait for the voltage measurement until the parasitic capacitance to be measured is charged with the common mode voltage and the potential difference disappears. As a result, it becomes easy to shorten the resistance measurement time and the inspection time.

Further, 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), the common mode voltage is fed back to the inverting amplifier circuit of the operational amplifier to make the operational amplifier. A method of canceling the common mode voltage at the output can be considered. However, in such a method, it is not easy to cancel the unstable common mode voltage because the feedback time delay due to the resistance component of the feedback circuit and the parasitic capacitance, the response delay of the operational amplifier, and the like occur.

On the other hand, according to the substrate inspection device 1, the constant current source CS1 and the constant current source CS2, which are connected in series and whose connection points are set to the ground potential, have a first current value I ₁ and a second current value I, respectively. As a result of trying to maintain the output current of ₂ , the common mode voltage becomes substantially zero, so that it is easy to reduce the common mode voltage.

The substrate inspection device 1 may be a resistance measuring device that does not include the substrate inspection unit 52, and steps S7 to S9 may not be executed. Further, the scanner 6 may not be provided. Further, the grounding probe PG is not necessarily limited to an example in which it is in contact with the outward electrode A2, that is, one end on the minus side of the wiring A3 (conductor). The ground probe PG is preferably in contact with one end on the minus side of the wiring A3, but may be in contact with the chip side electrode A1 which is one end on the plus side of the wiring A3, and is in contact with the intermediate portion of the wiring A3. May be good.

Further, the current probes Pc1 and Pc2 and the detection probes Pv1 and Pv2 are not necessarily limited to the cases where they are in contact with both ends of the wiring A3 (conductor) to be measured. Even when the current probes Pc1 and Pc2 and the detection probes Pv1 and Pv2 are in contact with the intermediate portion to be measured, the contact points between the current probe Pc1 and the detection probe Pv1 and the contact points between the current probe Pc2 and the detection probe Pv2. The resistance value between and can be measured.
(Second Embodiment)

Next, a substrate inspection device 1a using the resistance measuring device according to the second embodiment of the present invention will be described. FIG. 5 is a block diagram showing an example of the configuration of the substrate inspection device 1a using the resistance measuring device according to the second embodiment of the present invention. FIG. 6 is an explanatory diagram showing an equivalent circuit of the substrate inspection device 1a and the substrate A shown in FIG. The substrate inspection device 1a shown in FIGS. 5 and 6 and the substrate inspection device 1 shown in FIG. 1 differ in the following points.

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

Since other configurations are the same as those of the substrate inspection device 1 shown in FIG. 1, the description thereof will be omitted. In the case of the board inspection device 1a, as in the case of the board inspection device 1, the constant current source CS1 and the constant current source CS2, which are connected in series and whose connection points are set to the ground potential, have their first current values I ₁ respectively. , Attempts to maintain the output current of the second current value I ₂ . As a result, the current value I ₃ flowing through the resistor Rv2 becomes substantially zero, and the common mode voltage becomes substantially zero, so that it is easy to reduce the common mode voltage.

Further, according to the substrate inspection device 1a, since it is not necessary to separately provide the grounding probe PG, it is easy to reduce the cost as compared with the substrate inspection device 1. Further, since the number of probes to be brought into contact with the wiring A3 may be two, it is easier to bring the probes into contact with the wiring A3 than to the substrate inspection device 1 which needs to bring three probes into contact with the wiring A3.

By the way, the first current value I ₁ and the second current value I _{2 of} the constant current sources CS1 and CS2 are substantially the same (I ₁ ≈ I ₂ ), but the manufacturing variations and currents of the constant current sources CS1 and CS2 There may be some differences due to the control accuracy. When a difference occurs 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 value of the resistor Rv2 the resistance value Rv _2, the voltage of Rv ₂ × _{I 3} is generated by the resistor Rv2. Since this voltage is included in the measured voltage Vs measured by the voltage detection unit 4, a measurement error of the measured voltage Vs will occur.

On the other hand, in the substrate inspection device 1 shown in FIG. 2, when a difference occurs 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 is the resistance RG. Flow. The voltage generated by the current flowing through the resistor RG is not included in the measured voltage Vs in the substrate inspection device 1. Therefore, the substrate inspection device 1 is more preferable than the substrate inspection device 1a in that a measurement accuracy error due to a difference between the first current value I ₁ and the second current value I ₂ is less likely to occur.

1 Board inspection device (resistance measuring device)
4 Voltage detection unit 5 Control unit 6 Scanner 51 Resistance acquisition unit 52 Board inspection unit 61, 62, 63, 64, 65 Switch A Board A1 Chip side electrode (first electrode)
A2 extrovert 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 Measurement current 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 (grounding part)
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 Rref reference value Vs measured voltage

Claims (6)

A resistance measuring device for measuring the resistance of a conductor.
The first and second current probes for contacting the conductor to pass a predetermined measurement current, and
The first and second detection probes for contacting the conductor and detecting the voltage generated in the conductor by the measuring current,
A voltage detection unit that detects the voltage between the first and second detection probes, and
A first constant current source in which the positive electrode is connected to the first current probe, the negative electrode is connected to the ground, and a current of a preset first current value is output.
The 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, and the negative electrode is connected to the second current probe, which is substantially the same as the first current value. A second constant current source that outputs a current with a certain second current value,
A grounding portion that conducts a predetermined portion of the conductor with the ground,
A resistor acquisition unit that acquires the resistance based on the voltage detected by the voltage detection unit is provided .
The grounding portion includes a grounding probe for contacting the predetermined portion.
The ground probe is a resistance measuring device connected to the ground . A resistance measuring device for measuring the resistance of a conductor.
The first and second current probes for contacting the conductor to pass a predetermined measurement current, and
The first and second detection probes for contacting the conductor and detecting the voltage generated in the conductor by the measuring current,
A voltage detection unit that detects the voltage between the first and second detection probes, and
A first constant current source in which the positive electrode is connected to the first current probe, the negative electrode is connected to the ground, and a current of a preset first current value is output.
The 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, and the negative electrode is connected to the second current probe, which is substantially the same as the first current value. A second constant current source that outputs a current with a certain second current value,
A grounding portion that conducts a predetermined portion of the conductor with the ground,
E Bei a resistance acquisition unit for acquiring the resistance based on the voltage detected by the voltage detecting section,
The ground portion, the second detection probe is a wiring connected to the ground resistance measurement device. The resistance measuring device according to claim 1 or 2 ,
A substrate inspection apparatus including a substrate inspection unit formed on a substrate based on the resistance measured by the resistance measuring apparatus and inspecting wiring which is a conductor. It is a resistance measurement method that measures the resistance of a conductor.
(A) A step of bringing the first current probe and the first detection probe into contact with the conductor.
(B) A step of bringing the second current probe and the second detection probe into contact with each other at a position of the conductor separated from the contact positions of the first current probe and the first detection probe.
(C) The positive electrode is connected to the first current probe, the negative electrode outputs a current of the first current value preset by the first constant current source connected to the ground, and the positive electrode is the first constant current source. A second that is connected to the negative electrode and the ground and is connected in series with the first constant current source, and the negative electrode is substantially the same as the first current value by the second constant current source connected to the second current probe. The process of outputting the current of the current value and
(D) A step of conducting a predetermined portion of the conductor with the ground,
(E) The step of detecting the voltage between the first and second detection probes and
(F) viewing including the step of acquiring the resistance based on the voltage detected by said step (e),
The step (d) is a resistance measuring method, which is a step of bringing a grounding probe connected to the ground into contact with the predetermined portion . It is a resistance measurement method that measures the resistance of a conductor.
(A) A step of bringing the first current probe and the first detection probe into contact with the conductor.
(B) A step of bringing the second current probe and the second detection probe into contact with each other at a position of the conductor separated from the contact positions of the first current probe and the first detection probe.
(C) The positive electrode is connected to the first current probe, the negative electrode outputs a current of the first current value preset by the first constant current source connected to the ground, and the positive electrode is the first constant current source. A second that is connected to the negative electrode and the ground and is connected in series with the first constant current source, and the negative electrode is substantially the same as the first current value by the second constant current source connected to the second current probe. The process of outputting the current of the current value and
(D) A step of conducting a predetermined portion of the conductor with the ground,
(E) The step of detecting the voltage between the first and second detection probes and
(F) viewing including the step of acquiring the resistance based on the voltage detected by said step (e),
The second detection probe is connected to the ground and
The step (b) is a resistance measuring method that also serves as the step (d). A first electrode is provided at one end of the conductor, and a second electrode having a larger area than the first electrode is provided at the other end of the conductor.
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.
The resistance measuring method according to claim 4 , wherein the step (d) is a step of bringing the grounding probe into contact with the second electrode using the second electrode as the predetermined portion.

Images