JP6972843B2 - Calibration method of resistance measuring device, resistance measuring device, board inspection device, and reference resistor - Google Patents

Description

The present invention relates to a calibration method of a resistance measuring device for measuring resistance, a resistance measuring device, a substrate inspection device using the same, and a reference resistor.

Conventionally, a substrate inspection device provided with a measurement circuit for measuring resistance has been known to be provided with a reference resistor (standard device) having a known resistance for use in calibrating the measurement circuit (for example). , Patent Document 1). According to Patent Document 1, the measuring unit (measurement circuit) can measure resistance by the four-terminal method (paragraph 0055), and pin terminals C1 and C2 are connected to one end of a resistor R1 serving as a reference resistor to form a resistor. Connect the pin terminals C3 and C4 to the other end of R1 (paragraph 093, FIG. 11), connect the resistor R1 to the measurement circuit via the pin terminals C1 to C4, measure the resistance of the resistor R1 and resist. It is described that the difference from the known resistance value of R1 is calculated and the measurement circuit is calibrated (paragraph 0995).

Japanese Unexamined Patent Publication No. 2015-55516

By the way, when the resistance to be measured is low resistance, a low resistance reference resistor is required in order to calibrate a resistance measuring device capable of measuring low resistance. Further, in order to enable highly accurate resistance measurement even when the resistance value of the measurement target changes, a plurality of reference resistors having different resistance values are required for calibration.

However, it is difficult to obtain a resistor having a low resistance of about 1 mΩ, and even if it is commercially available, the available resistance value is limited, and it is difficult to obtain a reference resistor having an appropriate resistance value. As a method of obtaining such a low resistance reference resistor, it is conceivable to prepare a reference resistor having an arbitrary resistance value by, for example, processing copper to an appropriate length and thickness. However, copper has a larger temperature coefficient of resistance than resistors commercially available as electronic components. Therefore, a resistor using copper has a disadvantage that the accuracy of the resistance value is lowered. Further, it is necessary to make copper to a certain thickness and length in order to obtain a desired resistance value, and a low resistance resistor using copper is not easy to miniaturize.

An object of the present invention is to provide a reference resistor, a method for calibrating a resistance measuring device, a resistance measuring device, and a substrate inspection device, which make it easy to obtain a reference resistance value of low resistance.

The calibration method of the resistance measuring device according to the present invention is based on a current supply unit that supplies a measurement current to supply the measurement target, a voltage measurement unit for measuring the voltage generated in the measurement target, and the voltage measurement unit. It is a calibration method of a resistance measuring device including a resistance calculation unit that calculates a resistance value by dividing the measured measured voltage by the current value of the measurement current, and (a) each has a preset resistance value. A step of preparing a reference resistor in which a series resistance portion in which a plurality of set resistors having a plurality of set resistors are connected in series and a fundamental resistor having a preset basic resistance value Rs are connected in parallel, and (b) the reference resistor. The step of supplying the measurement current to the basic resistance by the current supply unit, and (c) both ends of the selection resistance unit which is one or a continuous part of the plurality of set resistances. The measured resistance value Rx is calculated by the step of measuring the voltage between them as the measured voltage by the voltage measuring unit and (d) dividing the measured voltage by the current value of the measuring current by the resistance calculating unit. The process includes (e) a step of acquiring a reference resistance value Rref represented by the following formula (A) as a calibration target value which is a target of the measured resistance value Rx. Reference resistance value Rref = Rs × Rt / Rz ... (A) However, Rt is the resistance value of the selective resistance portion, and Rz is the resistance value of the entire series resistance portion.

Further, the resistance measuring device according to the present invention is a resistance measuring device that measures the resistance of the measurement target, and is generated in the current supply unit that supplies the measurement current for supplying the measurement target and the measurement target. A voltage measuring unit for measuring voltage as a measured voltage, a series resistance unit in which a plurality of set resistors each having a preset resistance value are connected in series, and a basic resistance having a preset basic resistance value Rs. A reference resistor connected in parallel with the reference resistor, a current supply switching section for supplying the measurement current by the current supply section to the basic resistance of the reference resistor, and one of the plurality of set resistors. Alternatively, the measurement target switching unit that causes the voltage measurement unit to measure the voltage between both ends of the selection resistance unit, which is a part of the continuous set resistance, and the measurement voltage measured by the voltage measurement unit are measured. The resistance calculation unit that calculates the measured resistance value Rx by dividing by the current value of the current, and the reference resistance value Rref represented by the following formula (A) are the target values for calibration that are the targets of the measured resistance value Rx. It is equipped with a calibration unit to be acquired as. Reference resistance value Rref = Rs × Rt / Rz ... (A) However, Rt is the resistance value of the selective resistance portion, and Rz is the resistance value of the entire series resistance portion.

According to these configurations, a measurement current is supplied to the basic resistance of the reference resistor by the current supply unit, and the voltage generated across the basic resistance by this measurement current is applied to the series resistance unit, and the voltage is applied. The voltage is divided by the selective resistance unit and measured as the measured voltage by the voltage measuring unit. Further, the resistance calculation unit calculates the measured resistance value Rx by dividing the measured voltage measured by the voltage measuring unit by the current value of the measuring current. As a result, if the measurement result of the resistance measuring device is accurate, the obtained measured resistance value Rx becomes equal to the reference resistance value Rref represented by the formula (A). Therefore, the reference resistance value Rref can be used as the calibration target value. Further, from the equation (A), the reference resistance value Rref is smaller than the basic resistance value Rs of the basic resistance. In this case, the resistance value is larger than the reference resistance value Rref of the low resistance to be obtained, and therefore the reference resistance value Rref that can be used for calibration can be obtained by using the easily available basic resistance. It is easy to obtain the reference resistance value.

Further, it is preferable to further include a selection unit that selects one or a part of the plurality of setting resistances as the selection resistance unit.

According to this configuration, any selection resistance unit can be selected by the selection unit. If the selective resistance unit can be selected, the resistance value Rz of the selective resistance unit in the equation (A) can be selected, and as a result, the reference resistance value Rref can be changed.

Further, it is preferable that the calibration unit calibrates the resistance measuring device so that the measured resistance value Rx approaches the reference resistance value Rref represented by the following formula (A).

According to this configuration, the resistance measurement accuracy of the resistance measuring device can be adjusted.

Further, in the substrate inspection device according to the present invention, the above-mentioned resistance measuring device and the current supply switching unit switch the supply destination of the measurement current by the current supply unit to the measurement target, and the measurement target switching unit. Inspects the substrate to be measured based on the switching control unit that switches the measurement destination of the measured voltage to the measurement target by the voltage measurement unit and the measurement resistance value Rx calculated by the resistance calculation unit. It is equipped with a board inspection unit to perform.

According to this configuration, it is possible to configure a substrate inspection device that can easily obtain a low resistance reference resistance value for use in calibration.

Further, in the reference resistor according to the present invention, a series resistor portion in which a plurality of set resistors each having a preset resistance value are connected in series and a basic resistor having a preset basic resistance value Rs are connected in parallel. At least three of the reference resistor main body, a pair of current input terminals connected to both ends of the basic resistor to receive the input of the measurement current, and the connection points between the plurality of set resistors. Each is connected and includes a voltage measuring terminal for measuring a voltage corresponding to the reference resistance value Rref.

According to this configuration, the current of the measurement current received by the pair of current input terminals is supplied to the basic resistance of the reference resistor, and the voltage generated across the basic resistance by this measurement current is the series resistance section. The applied voltage is divided by a plurality of set resistors, and the divided voltage is generated between at least three voltage measuring terminals. When this voltage is divided by the measuring current, the reference resistance value Rref represented by the formula (A) is obtained. Therefore, the reference resistor can be used as a reference device for giving the reference resistance value Rref. Then, from the equation (A), the reference resistance value Rref is smaller than the basic resistance value Rs of the basic resistance. In this case, the reference resistance value Rref is larger than the reference resistance value Rref of the low resistance to be obtained, and therefore the reference resistance value Rref can be obtained by using the easily available basic resistance, so that the reference resistance value of the low resistance is obtained. Is easy.

Further, it is preferable that the basic resistance and the plurality of set resistances have a temperature coefficient of resistance smaller than that of copper.

According to this configuration, the reference resistor has better temperature stability than the low resistance reference device made of copper.

Further, the series resistance unit includes the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, and tenth resistances in this order as the plurality of set resistances. The resistance value of the first and second resistances is 10Ω × N, the resistance value of the third to eighth resistances is 30Ω × N, the resistance value of the ninth resistance is 10Ω × N, and the resistance value of the tenth resistance. Is 120Ω × N, N is a natural number, the basic resistance value Rs is 3.3mΩ + 3.3mΩ × 10 × M, M is an integer of 0 or more, and the connection point between the first to ninth resistances and the connection point. It is preferable that the voltage measurement terminal is connected to the end of the first resistance on the side opposite to the second resistance.

According to this configuration, two of the multiple voltage measurement terminals are selected, the voltage is measured, and the voltage is divided by the measurement current, so that the reference resistance value is a continuous value according to the selection method of the two. Rref can be obtained.

The reference resistor having such a configuration, the calibration method of the resistance measuring device, the resistance measuring device, and the substrate inspection device can easily obtain a reference resistance value of low resistance.

It is a block diagram which shows an example of the structure of the substrate inspection apparatus which used the resistance measuring apparatus which concerns on one Embodiment of this invention. It is a circuit diagram which shows an example of the structure of the reference resistor shown in FIG. It is explanatory drawing which shows an example of the look-up table which is stored in the storage part in advance. It is a block diagram which shows the example which applied the reference resistor to the substrate inspection apparatus which used the resistance measuring apparatus by the two-terminal measurement method. It is a block diagram which shows the structural example in the case of calibrating the substrate inspection apparatus which does not have a reference resistor by the calibration method which concerns on one Embodiment of this invention. It is a flowchart which shows an example of the calibration method of the resistance measuring apparatus which concerns on one Embodiment of this invention.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. 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 embodiment of the present invention. It should be noted that the configurations with the same reference numerals in the respective figures 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 reference resistor 3, a current supply unit CS, a voltage measuring unit 4, a current probe Pc1, a current probe Pc2, a detection probe Pv1, a detection probe Pv2, and a switching circuit 6 (switching circuit 6). It includes a current supply switching unit, a measurement target switching unit), a selection unit 7, and a control unit 5. Since the substrate inspection device 1 measures resistance for substrate inspection, it corresponds to an example of a resistance measuring device.

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 55, 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 may be a liquid crystal display or an 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 connected to the semiconductor chip are formed on one surface of the substrate A. A plurality of outward electrodes A2 for connecting the semiconductor chip to the outside are formed on the other surface of the substrate A.

Each chip-side electrode A1 and each outward electrode A2 are electrically connected to each other 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 of each wiring A3. Wiring A3 corresponds to an example of a measurement target. Hereinafter, the current probes Pc1 and Pc2 and the detection probes Pv1 and Pv2 may be simply referred to as probes Pc1, Pc2, Pv1 and Pv2.

The probes Pc1, Pc2, Pv1, and Pv2 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 in contact with the chip-side electrode A1 of the substrate A. The tips of the current probe Pc2 and the detection probe Pv2 are in contact with the outward electrode A2 at a position separated from the chip side electrode A1.

In FIG. 1, the probes Pc1, Pc2, Pv1, and Pv2 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. Probes Pc1, Pc2, Pv1, and Pv2 may be provided in the hundreds to thousands, respectively, corresponding to such a large number of inspection points.

The current supply unit CS is a constant current circuit through which a constant current flows. The current value Is of the measuring current I is, for example, about 20 mA. The current supply unit CS supplies the measurement current I to the reference resistor 3 between the current probes Pc1 and Pc2 selected by the switching circuit 6 or via the selection unit 7.

The voltage measuring unit 4 measures the voltage between the detection probes Pv1 and Pv2, or the voltage of the selective resistance terminal of the reference resistor 3 described later. The voltage measuring unit 4 is configured by using, for example, an analog-digital converter, a voltage dividing resistor, or the like. The voltage measuring unit 4 measures the voltage between the detection probes Pv1 and Pv2 selected by the switching circuit 6 as the measured voltage Vx, or measures the voltage of the selected resistance terminal as the measured voltage Vx, and obtains data indicating the measured voltage Vx. Output to the control unit 5.

The reference resistor 3 provides a reference resistance value Rref as a reference for calibration. FIG. 2 is a circuit diagram showing an example of the configuration of the reference resistor 3 shown in FIG. The reference resistor 3 shown in FIG. 2 includes a reference resistor main body 31, terminals Ts1, Ts2 (current input terminals), and terminals T1, T2, T3, T4, T5, T6, T7, T8, T9 (for voltage measurement). It has a terminal).

The reference resistor main body 31 has a resistor Rstd (basic resistor) and resistors R1 (first resistor), R2 (second resistor), R3 (third resistor), R4 (fourth resistor), and R5 (fifth resistor). , R6 (sixth resistor), R7 (seventh resistor), R8 (eighth resistor), RA (nineth resistor), RB (tenth resistor) are connected in series to the series resistance section 32. Has been done. The resistors R1, R2, R3, R4, R5, R6, R7, R8, RA, and RB correspond to an example of the set resistance.

The terminal Ts1 is connected to one end of the resistor Rstd, and the terminal Ts2 is connected to the other end of the resistor Rstd. The terminal T1 is connected to the end of the resistor R1 opposite to the resistor R2, and the terminals T2 to T9 are connected to the connection points between the resistors R1 to R8 and RA, respectively. The temperature coefficients of the resistors Rstd and the resistors R1 to R8, RA, and RB are set to be smaller than the temperature coefficient of copper.

Hereinafter, the resistance value of the resistor Rstd Rs, the resistance value _R 1 to R ₈ of the resistors R1 to R8, the resistor RA, the resistance value of the RB is denoted Ra, and Rb.

The switching circuit 6 is capable of switching the connection destination of the current supply unit CS between the current probes Pc1 and Pc2 and the reference resistor 3. Further, the switching circuit 6 is capable of switching the connection destination of the voltage measuring unit 4 between the detection probes Pv1 and Pv2 and the selection unit 7.

The changeover circuit 6 includes a plurality of switches including, for example, switches 61a, 61b, 62a, 62b, 63a, 63b, 64a, 64b. These switches 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.

Specifically, the positive electrode (+) of the current supply unit CS is connected to one end of the switch 61a and one end of the switch 61b, the other end of the switch 61a is connected to the current probe Pc1, and the other end of the switch 61b is the reference. It is connected to the terminal Ts1 of the resistor 3. The negative electrode (-) of the current supply unit CS is connected to one end of the switch 62a and one end of the switch 62b, the other end of the switch 62a is connected to the current probe Pc2, and the other end of the switch 62b is the terminal of the reference resistor 3. It is connected to Ts2.

The positive electrode side (+) terminal of the voltage measuring unit 4 is connected to one end of the switch 63a and one end of the switch 63b, the other end of the switch 63a is connected to the detection probe Pv1, and the other end of the switch 63b connects the selection unit 7. It is connected to the reference resistor 3 via. The negative electrode side (-) terminal of the voltage measuring unit 4 is connected to one end of the switch 64a and one end of the switch 64b, the other end of the switch 64a is connected to the detection probe Pv2, and the other end of the switch 64b connects the selection unit 7. It is connected to the reference resistor 3 via.

As a result, when the switches 61a and 62a are turned on and the switches 61b and 62b are turned off, the supply destination of the measurement current I is switched to the wiring A3 side to be measured, and the resistance of the wiring A3 can be measured. .. On the other hand, when the switches 61a and 62a are turned off and the switches 61b and 62b are turned on, the supply destination of the measurement current I is switched to the terminals Ts1 and Ts2 of the reference resistor 3 so that they can be calibrated. The switches 61a, 61b, 62a, 62b correspond to an example of the current supply switching unit.

When the switches 63a and 64a are turned on and the switches 63b and 64b are turned off, the measurement destination of the measured voltage Vx by the voltage measuring unit 4 is switched to the wiring A3 side to be measured, and the resistance of the wiring A3 can be measured. NS. On the other hand, when the switches 63a and 64a are turned off and the switches 63b and 64b are turned on, the measurement destination of the voltage Vx measured by the voltage measuring unit 4 is switched to the terminal-to-terminal side of the reference resistor 3 selected by the selection unit 7. , Ready to calibrate. The switches 63a, 63b, 64a, 64b correspond to an example of the measurement target switching unit.

The selection unit 7 is a so-called multiplexer circuit. The selection unit 7 selects two terminals T1 to T9 according to the control signal from the control unit 5 and connects them to the switches 63b and 64b to select a selection resistance unit between the selected two terminals. .. Hereinafter, the two terminals located at both ends of the selective resistance portion are referred to as selective resistance terminals. That is, the resistance sandwiched between the selection resistance terminals is the selection resistance portion.

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 storage device is also used as the storage unit 56. The control unit 5 functions as a switching control unit 52, a resistance calculation unit 53, a calibration unit 54, and a board inspection unit 55 by executing a predetermined control program.

FIG. 3 is an explanatory diagram showing an example of a look-up table LUT stored in the storage unit 56 in advance. Look-up table LUT shown in FIG. 3, the reference resistor 3 shown in FIG. 2, the resistance value _R 1, _{R 2} 10 [Omega, a resistance value _R 3 to R ₈ in the case of a 30 [Omega, selected resistor terminal and select the resistor The resistance value Rt of the unit and the reference resistance value Rref are associated with each other.

For example, the description of "T3-T2: 10Ω" in the look-up table LUT means that the selection resistance terminal is the terminals T3 and T2, and the resistance value Rt of the selection resistance portion sandwiched between the terminals T3 and T2 is 10Ω. Is shown.

Types A to E show that different reference resistance values Rref can be obtained depending on the difference in resistance values Rs, Ra, and Rb. In the reference resistor 3 shown in FIG. 2, since the resistance values Rs, Ra, and Rb are fixed values, only the portion corresponding to the type of the reference resistor 3 provided in the substrate inspection device 1 is used as the look-up table LUT. It may be stored in the storage unit 56.

There is a relationship represented by the following formula (A) between the reference resistance value Rref, the resistance value Rs of the resistance Rstd, and the resistance value Rt of the selective resistance portion.

Reference resistance value Rref = Rs × Rt / Rz ・ ・ ・ (A)
However, Rz is the resistance value of the entire series resistance unit 32, and Rz = R ₁ + R ₂ + R ₃ + R ₄ + R ₅ + R ₆ + R ₇ + R ₈ + Ra + Rb = 330Ω. The look-up table LUT is calculated in advance based on the equation (A) and stored in the storage unit 56.

For example, in type A, if the selective resistance terminals are terminals T3 and T2, Rs = 3.3 mΩ, Rt = 10 Ω, and Rz = 330 Ω. Therefore, when substituted into the equation (A), the reference resistance value Rref = 3. 3mΩ × 10Ω / 330Ω = 0.1mΩ, which matches the look-up table LUT.

When the switching control unit 52 measures the resistance of the measurement target, the switches 61a, 61b, 62a, 62b switch the supply destination of the measurement current I by the current supply unit CS to the substrate A, and the switches 63a, 63b, By 64a and 64b, the measurement destination of the measured voltage Vx by the voltage measuring unit 4 is switched to the substrate A. Hereinafter, this switching state is referred to as a measurement mode.

Further, when calibrating the resistance measurement, the switching control unit 52 switches the supply destination of the measurement current I by the current supply unit CS to the terminals Ts1 and Ts2 (resistance Rstd) by the switches 61a, 61b, 62a, 62b. Then, the switches 63a, 63b, 64a, 64b switch the measurement destination of the voltage measured by the voltage measuring unit 4 to the selection resistance unit of the reference resistor 3 selected by the selection unit 7. Hereinafter, this switching state is referred to as a calibration mode.

As a result, in the calibration mode, the measurement current I is supplied by the current supply unit CS to the resistance Rstd (basic resistance) of the reference resistor 3 (step (b)), and the voltage between both ends of the selection resistance unit is a voltage. It is measured as a measured voltage Vx by the measuring unit 4 (step (c)).

In the present specification, "calibration" means a value indicated by an instrument or a measuring system (measured resistance value Rx) and a value realized by a standard (reference resistance) in accordance with the definition of JIS Z 8103: 2000 "measurement term". It means to establish the relationship with the value Rref), and does not necessarily include adjusting the substrate inspection device 1 to correct the error.

The resistance calculation unit 53 calculates the measured resistance value Rx using the following equation (1) based on the measured voltage Vx detected by the voltage measuring unit 4 and the current value Is of the measuring current I (step (step (step)). d)).
Measurement resistance value Rx = Vx / Is ... (1)

The substrate inspection device 1 (resistance measuring device) includes a current measuring unit that measures the actual current value Is of the measuring current I, and the resistance calculating unit 53 measures the current value Is measured by the current measuring unit. The measured resistance value Rx may be calculated using the voltage Vx.

The calibration unit 54 refers to the look-up table LUT stored in the storage unit 56, and acquires the reference resistance value Rref corresponding to the selection resistance terminal selected by the selection unit 7 (step (e)). Since the reference resistance value Rref of the look-up table LUT is set to the value represented by the formula (A), the calibration unit 54 refers to the look-up table LUT to refer to the reference resistance value represented by the formula (A). Rref can be acquired as a calibration target value which is a target of the measured resistance value Rx. The principle of obtaining the reference resistance value Rref, which is the target value of calibration, by the formula (A) will be described later.

The calibration unit 54 is not necessarily limited to the example of acquiring the reference resistance value Rref by referring to the look-up table LUT. The calibration unit 54 may acquire the reference resistance value Rref by actually executing the calculation of the equation (A).

Further, the calibration unit 54 may acquire the reference resistance value Rref set in advance or input to the substrate inspection device 1 from the outside as it is. Then, the calibration unit 54 acquires the selection resistance terminal corresponding to the reference resistance value Rref with reference to the above lookup table, and causes the selection unit 7 to select the voltage measurement terminal corresponding to the selection resistance terminal. You may do it.

In the calibration mode, if the measured resistance value Rx is calculated by the resistance calculation unit 53 and the reference resistance value Rref is obtained by the calibration unit 54, it is realized by the value indicated by the instrument or the measurement system (measured resistance value Rx) and the standard. Since the relationship with the value to be determined (reference resistance value Rref) is associated and determined, the steps (b) to (e) correspond to calibration.

The calibration unit 54 adjusts the current supply unit CS, the voltage measurement unit 4, the current measurement unit that measures the actual current value Is of the measurement current I, and the like so that the measurement resistance value Rx approaches the reference resistance value Rref. The process of correcting the error may be executed.

Alternatively, the calibration unit 54 executes steps (b) to (e) while sequentially switching, for example, the selection resistance unit (selection resistance terminal), and the measured resistance value Rx and the reference obtained corresponding to each selection resistance unit. A calibration table associated with the resistance value Rref or a calibration table associated with the measured resistance value Rx and the difference between the measured resistance value Rx and the reference resistance value Rref may be created and stored in the storage unit 56. Then, the resistance calculation unit 53 calculates the measured resistance value Rx in the measurement mode, then refers to the calibration table and calculates the measured resistance value Rx based on the reference resistance value Rref or the difference associated with the measured resistance value Rx. It may be corrected.

Further, the calibration unit 54 displays calibration information including the measured resistance value Rx and the reference resistance value Rref on, for example, a display device shown in the figure, or transmits the calibration information to the outside using the communication circuit shown in the figure. The maintenance worker, the user, or the like may be notified. The maintenance worker or the like who has been notified of the calibration information can adjust the substrate inspection device 1 so that the measured resistance value Rx approaches the reference resistance value Rref based on the notified calibration information.

In the measurement mode, the board inspection unit 55 inspects the wiring A3 to be measured based on the measured resistance value Rx calculated by the resistance calculation unit 53. Specifically, the substrate inspection unit 55 compares the determination reference value RR stored in the storage unit in advance with the measurement resistance value Rx, and if the measurement resistance value Rx is smaller than the determination reference value RR, the wiring A3. Is determined to be a non-defective product, and if the measured resistance value Rx is equal to or greater than the determination reference value RR, the wiring A3 is determined to be defective.

Next, the principle of obtaining the reference resistance value Rref, which is the target value for calibration, based on the look-up table LUT, that is, the equation (A), will be described using the reference resistor 3.

In the calibration mode, the switching circuit 6 supplies the measurement current I of the current value Is output from the current supply unit CS to the terminals Ts1 and Ts2, and flows them to the resistor Rstd. Since the resistor Rstd and the series resistance section 32 are connected in parallel, strictly speaking, the measurement current I is divided between the resistor Rstd and the series resistance section 32. However, if the resistance value Rz of the series resistance unit 32 is sufficiently larger than the resistance value Rs of the resistance Rstd, the current flowing through the series resistance unit 32 can be ignored. Therefore, the measurement current I will be described by approximating the current flowing through the resistor Rstd.

For example, in the case of type A shown in the look-up table LUT, the resistance value Rz = 330Ω of the series resistance unit 32, the resistance value Rs = 3.3 mΩ of the resistance Rstd, and Rz: Rs = 1000000: 1. Since the current value flowing through Rz and Rs is the inverse ratio of the resistance ratio, the current flowing through the series resistance portion 32 is 1/10000 of the current flowing through the resistor Rstd, which can be substantially ignored.

When the measuring current I of the current value Is flows through the resistor Rstd, the voltage Vs between both ends of the resistor Rstd becomes Vs = Is × Rs. Since the resistor Rstd and the series resistance section 32 are connected in parallel, the voltage Vs is also applied to the series resistance section 32. Then, the measured voltage Vx generated between the two selective resistance terminals is represented by the following equation (2) by dividing the voltage between the resistance value Rz of the series resistance portion 32 and the resistance value Rt of the selective resistance portion 32.
Measurement voltage Vx = Vs × (Rt / Rz) = Is × Rs × Rt / Rz ・ ・ ・ (2)

Here, from the equation (A), the reference resistance value Rref = Rs × Rt / Rz. Substituting equation (A) into equation (2),

Measured voltage Vx = Is × Rref ・ ・ ・ (3)
Will be.

In the calibration mode, the selection resistance terminal is connected to the voltage measurement unit 4 by the switching circuit 6 and the selection unit 7, and the measured voltage Vx generated between the two selection resistance terminals is measured by the voltage measurement unit 4. From the measured voltage Vx measured by the voltage measuring unit 4, the resistance calculating unit 53 calculates the measured resistance value Rx using the above equation (1). Here, by substituting the equation (3) into the equation (1), the following equation (4) is obtained.
Measurement resistance value Rx = Vx / Is = (Is × Rref) / Is = Rref ... (4)

From the equation (4), the measured resistance value Rx calculated by the resistance calculation unit 53 in the calibration mode is equal to the reference resistance value Rref.

That is, if the current value Is of the measurement current I output from the current supply unit CS and the detection accuracy of the voltage measurement unit 4 are accurate, the current is relative to the resistance Rstd (basic resistance) of the reference resistor 3. The step (b) of supplying the measurement current I by the supply unit CS, the step (c) of measuring the voltage between both ends of the selective resistance unit as the measurement voltage Vx by the voltage measurement unit 4, and the resistance calculation unit 53. By executing the step (d) of calculating the measured resistance value Rx by dividing the measured voltage Vx by the current value Is of the measuring current I, the reference resistor 3 has the reference resistance value Rref equivalently. It can be seen that it can be used as a reference resistor.

Therefore, if the measurement accuracy of the resistance measurement circuit system including the current supply unit CS, the voltage measurement unit 4, and the resistance calculation unit 53 is accurate, the measured resistance value Rx obtained by the resistance calculation unit 53 in the calibration mode is expressed by the equation ( Since it should match the reference resistance value Rref shown in A), that is, the reference resistance value Rref shown in the lookup table LUT, the calibration unit 54 can use the reference resistance value Rref as the target value for calibration.

Here, from the equation (A), since the reference resistance value Rref = Rs × Rt / Rz, the reference resistance value Rref smaller than the resistance value Rs of the resistance Rstd can be obtained by the voltage division ratio (Rt / Rz). ..

For example, as in Type A shown in FIG. 3, if one resistor having a resistance value Rs of 3.3 mΩ is used as the resistor Rstd, the resistors R1 to R8, RA, and RB are only used for voltage division, and are therefore available on the market. A resistance value that is easy to use, for example, a resistance of 10 to 120 Ω can be used. As a result, the reference resistor 3 can be configured by using one low resistance 3.3 mΩ resistor Rstd and a resistor in the easily available resistance value range.

Further, according to the reference resistor 3, it is easy to obtain a reference resistance value Rref of 0.1 mΩ to 2.0 mΩ, which is difficult to obtain in the market because the resistance is lower than the resistance Rstd of 3.3 mΩ. Since it can be obtained by combining resistors R1 to R8, RA, RB, and resistors Rstd having a high resistance value, it becomes easy to obtain a reference resistance value Rref having a low resistance.

Further, a special resistance having a low resistance such as 0.2 mΩ is not only difficult to obtain, but also likely to be expensive even if it can be obtained. On the other hand, the resistors R1 to R8, RA, RB, Rstd are likely to be easier and cheaper to obtain than special resistors such as 0.2 mΩ, and therefore more than when such special resistors are used. There is a possibility that the reference resistor 3 can be made at a lower cost.

Further, the reference resistor 3 includes a plurality of voltage measuring terminals T1 to T9, and by selecting a selective resistance terminal from these, a plurality of types of reference resistance value Rref can be obtained. Therefore, it is not necessary to provide a plurality of reference resistors having different resistance values, which improves convenience. Further, there is a possibility that the reference resistor 3 can be made at a lower cost than having a plurality of reference resistors.

For example, in the types A to E shown in FIG. 3, by increasing the resistance value Rs by 10 times, in the type A, a reference resistance value Rref in 0.1 mΩ increments is obtained from 0.1 mΩ to 2.0 mΩ, and the type. In B, a reference resistance value Rref from 1 mΩ to 20 mΩ in 1 mΩ increments is obtained, and in types C, D, and E, a reference resistance value Rref that is 10 times larger is obtained, and a desired reference resistance is obtained simply by changing the resistance value Rs. Since the value Rref can be obtained, it is highly convenient.

Thus, the reference resistor 3 which reference resistance value Rref of successive values are obtained, the resistor R1, the resistance value of R2 _R 1, _{R 2} a 10 [Omega × N, the resistance value _R 3 to R ₈ in the resistance R3~R8 Is 30Ω × N, the resistance value Ra of the resistor RA is 10Ω × N, the resistance value Rb of the resistor RB is 120Ω × N, N is a natural number, and the resistance value Rs of the resistor Rstd is 3.3mΩ + 3.3mΩ × 10 × M, M. Is obtained by setting it to an integer greater than or equal to 0.

Further, when a reference resistor is produced by processing copper, the resistance temperature coefficient of copper is large, so that the resistance value fluctuates due to the temperature change, and the resistance value becomes unstable. On the other hand, in the case of the reference resistor 3, since it can be manufactured by combining a commercially available resistor having a temperature coefficient of resistance much smaller than that of copper without using copper, it is possible to manufacture a reference resistor by processing copper. A much more stable reference resistor can be easily obtained. For example, the temperature coefficient of copper is 0.00393 [1 / ° C.], whereas the temperature coefficient of resistance of MPP series ultra-precision chip resistors manufactured by Alpha Electronics is ^{about 0.2 × 10 -6} / ° C. For example, in the low resistance metal plate resistor ERJM03N manufactured by Panasonic Corporation, the temperature coefficient of resistance ^{is about 100 × 10 -6} / ° C.

Moreover, since a small chip resistor is commercially available, it is easier to reduce the size than when the resistor is made of copper. In addition, since it is only necessary to obtain a commercially available resistor, there is a high possibility that the lead time and processing cost will be lower than those for processing copper.

Although an example in which the reference resistor 3 is provided in the substrate inspection device 1 that measures resistance by the four-terminal measurement method is shown, for example, as shown in FIG. 4, one probe is used instead of the current probe Pc1 and the detection probe Pv1. Even in the case of a substrate inspection device 1a equipped with Pr1, equipped with one probe Pr2 instead of the current probe Pc2 and the detection probe Pv2, and performing a two-terminal measurement method that combines current supply and voltage measurement with one probe. , The reference resistor 3 can be used for calibration.

Further, the reference resistor 3 does not necessarily have to be incorporated in the substrate inspection device 1 or the resistance measuring device. For example, as shown in FIG. 5, a substrate inspection device 1b or a resistance measuring device that measures resistance by a four-terminal measurement method and does not include a reference resistor 3, a switching control unit 52, and a calibration unit 54. Alternatively, the resistance measuring device can be calibrated by the calibration method of the resistance measuring device according to the present invention.

In this case, as shown in FIG. 5, the reference resistor 3 is prepared (step (a)), and the current probes Pc1 and Pc2 are brought into contact with the terminals Ts1 and Ts2 of the reference resistor 3 for measurement from the current supply unit CS. The current I is supplied (step (b)), the detection probes Pv1 and Pv2 are brought into contact with the selective resistance terminal of the reference resistor 3, and the measured voltage Vx is measured by the voltage measuring unit 4 (step (c)), and the resistance is calculated. The measured resistance value Rx may be calculated by the unit 53 (step (d)), and this may be notified to the maintenance worker or the like. The maintenance worker or the like obtains the reference resistance value Rref corresponding to the selected resistance terminal by referring to the look-up table LUT (step (e)), and compares it with the measured resistance value Rx to inspect the substrate. It is possible to calibrate 1b or the resistance measuring device.

FIG. 6 is a flowchart showing an example of a calibration method of the resistance measuring device according to the embodiment of the present invention. First, the reference resistor 3 is prepared (step (a)). In the step (a), as shown in FIGS. 1 and 4, the reference resistor 3 is incorporated in the resistance measuring device such as the substrate inspection devices 1 and 1a, and as shown in FIG. 5, the reference resistor 3 is incorporated. Is included as a measurement target outside the resistance measuring device such as the substrate inspection device 1b.

Next, the measurement current I is supplied to the resistance Rstd of the reference resistor 3 by the current supply unit CS (step (b)). In the step (b), as shown in FIGS. 1 and 4, a mode in which the measurement current I is supplied to the resistor Rstd by internal wiring in the resistance measuring device such as the substrate inspection devices 1 and 1a, and a mode shown in FIG. As described above, the embodiment in which the current is supplied via the current probes Pc1 and Pc2 included in the resistance measuring device such as the substrate inspection device 1b is included.

In the embodiment in which the measurement current I is supplied to the resistor Rstd by internal wiring, the reference resistor 3 does not necessarily have to include the terminals Ts1 and Ts2, and may be directly wired to both ends of the resistor Rstd.

Next, the voltage between both ends of the selective resistance unit is measured by the voltage measuring unit 4 as the measured voltage Vx (step (c)). In the step (c), as shown in FIGS. 1 and 4, the voltage measuring unit 4 is connected to both ends of the selected resistance unit for measurement via the internal wiring in the resistance measuring device such as the substrate inspection devices 1 and 1a. A mode of measuring the voltage Vx and a mode of measuring the measured voltage Vx by contacting the detection probes Pv1 and Pv2 included in the resistance measuring device such as the substrate inspection device 1b with the selective resistance terminal are included.

Next, the resistance calculation unit 53 calculates the measured resistance value Rx by dividing the measured voltage Vx by the current value Is of the measuring current I (step (d)).

Next, the reference resistance value Rref represented by the above formula (A) is acquired as the target value for calibration, which is the target of the measured resistance value Rx (step (e)). In the step (e), the calibration unit 54 of the substrate inspection devices 1, 1a and the like as shown in FIGS. 1 and 4 acquires the reference resistance value Rref, and as shown in FIG. 5, the reference resistor 3 and the like. A reference resistor 3 is connected to a resistance measuring device such as a substrate inspection device 1b that does not have a calibration unit 54 as a measurement target, and the current probes Pc1 and Pc2 and the detection probes Pv1 and Pv2 are brought into contact with each other, and a maintenance worker or the like is created in advance. The reference resistance value Rref represented by the formula (A) by referring to the lookup table LUT, that is, the reference resistance value Rref corresponding to the selective resistance terminal to which the detection probes Pv1 and Pv2 are contacted is determined by the measured resistance value Rx. The mode to be acquired as the target value of the calibration which is the target is included.

As described above, according to the steps (a) to (e), the reference resistance value Rref, which is the target value (reference value) for calibration, can be obtained by using the reference resistor 3.

Although an example in which 10 resistors R1 to R8, RA, and RB are used as the set resistance is shown, the set resistance may be two or more. If there are at least two set resistors, the effect of the resistance voltage divider in the above equation (2) can be obtained by setting the total resistance value of the two to Rz and the resistance value of the selected resistor selected from the two to Rt. Obtained and therefore formula (A) can be applied. As a result, since the reference resistance value Rref smaller than the resistance Rstd can be obtained, it is possible to construct a reference resistor in which it is easy to obtain a reference resistance value having a low resistance.

Further, although nine terminals T1 to T9 are shown as an example of the voltage measurement terminals, the voltage measurement terminals may be connected to at least three of the connection points between the plurality of set resistors. If there are three voltage measurement terminals connected to each of the three locations, it is possible to select at least two types of selective resistors.

Further, the substrate inspection devices 1 and 1b may not include the selection unit 7, and the selection resistance terminal (selection resistance unit) may be fixedly connected to the switching circuit 6.

Further, the temperature coefficient of resistance of the resistors R1 to R8, RA, RB, and Rstd is not necessarily limited to the example smaller than that of copper. Even when the temperature coefficient of resistance of the resistors R1 to R8, RA, RB, and Rstd is copper or higher, a reference resistance value Rref smaller than the resistance Rstd can be obtained, and therefore a reference resistance value of low resistance can be obtained. It is possible to construct a reference resistor that is easy to do.

Further, the substrate inspection devices 1, 1a and 1b may be configured as a resistance measuring device that does not include the substrate inspection unit 55.

1,1a, 1b Board inspection device (resistance measuring device)
3 Reference resistor 4 Voltage measuring unit 5 Control unit 6 Switching circuit (current supply switching unit, measurement target switching unit)
7 Selection unit 31 Reference resistance main unit 32 Series resistance unit 52 Switching control unit 53 Resistance calculation unit 54 Calibration unit 55 Board inspection unit 56 Storage unit 61a, 61b, 62a, 62b Switch (current supply switching unit)
63a, 63b, 64a, 64b switch (measurement target switching unit)
A Substrate A1 Chip side electrode A2 Extraverted electrode A3 Wiring (measurement target)
CS current supply unit I Measurement current Is current value (current value of measurement current I)
LUT Look-up table Pc1, Pc2 Current probe Pr1, Pr2 Probe Pv1, Pv2 Detection probe R1 to R8, RA, RB Resistance (set resistance)
RR Judgment reference value Rref Reference resistance value Rstd resistance (basic resistance)
Rs resistance value (Rstd resistance value)
Rt resistance value (resistance value of the selective resistance part)
Rx measurement resistance value Rz resistance value (resistance value of the entire series resistance part)
T1 to T9 terminals (voltage measurement terminals)
Ts1, Ts2 terminal (current input terminal)
Vs voltage (voltage across Rstd)
Vx measured voltage

Claims (7)

The current supply unit that supplies the measurement current to supply to the measurement target, the voltage measurement unit for measuring the voltage generated in the measurement target, and the measurement voltage measured by the voltage measurement unit are the current of the measurement current. It is a calibration method of a resistance measuring device including a resistance calculation unit that calculates a resistance value by dividing by a value.
(A) Prepare a reference resistor in which a series resistor unit in which a plurality of set resistors each having a preset resistance value are connected in series and a basic resistor having a preset basic resistance value Rs are connected in parallel. And the process to do
(B) A step of supplying the measurement current to the basic resistance of the reference resistor by the current supply unit.
(C) A step of causing the voltage measuring unit to measure the voltage between both ends of the selective resistance portion, which is one or a continuous part of the set resistances among the plurality of set resistors, as the measured voltage.
(D) A step of calculating the measured resistance value Rx by dividing the measured voltage by the current value of the measuring current by the resistance calculation unit.
(E) A calibration method of a resistance measuring device including a step of acquiring a reference resistance value Rref represented by the following formula (A) as a calibration target value which is a target of the measured resistance value Rx.
Reference resistance value Rref = Rs × Rt / Rz ・ ・ ・ (A)
However, Rt is the resistance value of the selective resistance portion, and Rz is the resistance value of the entire series resistance portion. A resistance measuring device that measures the resistance of the object to be measured.
A current supply unit that supplies a measurement current to supply the measurement target,
A voltage measuring unit for measuring the voltage generated in the measurement target as a measurement voltage,
A series resistor unit in which a plurality of set resistors each having a preset resistance value are connected in series, a reference resistor in which a basic resistor having a preset basic resistance value Rs is connected in parallel, and a reference resistor.
A current supply switching unit that supplies the measurement current to the basic resistance of the reference resistor by the current supply unit.
A measurement target switching unit that causes the voltage measuring unit to measure the voltage between both ends of the selective resistance unit, which is one or a part of the set resistances of the plurality of set resistors, as the measured voltage.
A resistance calculation unit that calculates the measured resistance value Rx by dividing the measured voltage measured by the voltage measuring unit by the current value of the measuring current.
A resistance measuring device including a calibration unit that acquires a reference resistance value Rref represented by the following formula (A) as a calibration target value that is a target of the measured resistance value Rx.
Reference resistance value Rref = Rs × Rt / Rz ・ ・ ・ (A)
However, Rt is the resistance value of the selective resistance portion, and Rz is the resistance value of the entire series resistance portion. The resistance measuring apparatus according to claim 2, further comprising a selection unit for selecting one or a part of the plurality of setting resistances as the selection resistance unit. The resistance measuring device according to claim 2 or 3, wherein the calibration unit calibrates the resistance measuring device so that the measured resistance value Rx approaches the reference resistance value Rref represented by the following formula (A). The resistance measuring device according to any one of claims 2 to 4,
The current supply switching unit switches the supply destination of the measurement current by the current supply unit to the measurement target, and the measurement target switching unit switches the measurement destination of the measurement voltage by the voltage measurement unit to the measurement target. Switching control unit to switch and
A substrate inspection device including a substrate inspection unit that inspects the substrate to be measured based on the measured resistance value Rx calculated by the resistance calculation unit. A reference resistance main unit in which a series resistance unit in which a plurality of set resistors each having a preset resistance value are connected in series and a basic resistance unit having a preset basic resistance value Rs are connected in parallel, and
A pair of current input terminals connected to both ends of the basic resistor to receive the input of measurement current,
A reference resistor that is connected to at least three of the connection points between the plurality of set resistors and includes a voltage measuring terminal for measuring a voltage corresponding to the reference resistance value Rref. The reference resistor according to claim 6, wherein the basic resistor and the plurality of set resistors have a temperature coefficient of resistance smaller than that of copper.

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