JP2019060767A - Calibration method of resistance measuring device, resistance measuring device, substrate inspection device, and reference resistor - Google Patents

Abstract

To provide a reference resistor capable of easily obtaining a low-resistance reference resistance value, a calibration method of a resistance measuring device, the resistance measuring device, and a substrate inspection device.SOLUTION: A reference resistor 3 includes: a reference resistance body 31 in which a series resistance section 32 in which a plurality of setting resistors R1-R8, RA, RB each of which has a preset resistance value are series-connected and a basic resistor Rstd having a preset basic resistance value Rs are parallel-connected; a pair of current input terminals Ts1 and Ts2 connected with both ends of the basic resistor Rstd for receiving an input of measurement current; and voltage measurement terminals T1-T9 each connected with at least three places of connection points among the plurality of setting resistors R1-R8, RA, RB for measuring voltage corresponding to the reference resistance value Rref.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method of calibrating a resistance measurement device that measures a resistance, a resistance measurement device, a substrate inspection device using the same, and a reference resistor.

  Conventionally, in a substrate inspection apparatus provided with a measurement circuit for measuring resistance, one having a reference resistor (standard unit) having a known resistance for use in calibration of the measurement circuit is known (for example, Patent Document 1). According to Patent Document 1, the measurement unit (measurement circuit) can measure resistance by the four-terminal method (Paragraph 0055), and the pin terminals C1 and C2 are connected to one end of the resistor R1 serving as a reference resistor. Connecting the pin terminals C3 and C4 to the other end of R1 (paragraph 0093, FIG. 11) and connecting the resistor R1 to the measurement circuit via the pin terminals C1 to C4 and measuring the resistance of the resistor R1 It is described that the difference from the known resistance value of R1 is calculated to calibrate the measurement circuit (paragraph 0095).

JP, 2015-55516, A

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

  However, a low resistance resistor of about 1 mΩ is difficult to obtain, and even if it is commercially available, the available resistance is limited, and it is difficult to obtain a reference resistor having an appropriate resistance. As a method of obtaining such a low resistance reference resistor, for example, it is conceivable to fabricate a reference resistor having an arbitrary resistance value by processing copper to an appropriate length and thickness. However, copper has a large temperature coefficient of resistance as compared to resistors commercially available as electronic components. Therefore, in the resistor using copper, there is a disadvantage that the accuracy of the resistance value is lowered. In addition, copper needs to have a certain thickness and length in order to achieve 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 of calibrating a resistance measurement device, a resistance measurement device, and a substrate inspection device which make it easy to obtain a low resistance reference resistance value.

  A calibration method of a resistance measuring device according to the present invention comprises: a current supply unit for supplying a measurement current to be supplied to a measurement object; a voltage measurement unit for measuring a voltage generated in the measurement object; and the voltage measurement unit A calibration method for a resistance measuring device, comprising: a resistance calculating unit that calculates a resistance value by dividing a measured voltage measured by a current value of the measurement current, wherein (a) each has a preset resistance value. Preparing a reference resistor in which a series resistance unit having a plurality of setting resistances connected in series and a basic resistance having a preset basic resistance value Rs connected in parallel; (b) the reference resistance A step of causing the current supply unit to supply the measurement current to the base resistor, and (c) both ends of the selection resistor which is one or a continuous portion of the plurality of setting resistors. Voltage between (D) calculating a measured resistance value Rx by dividing the measured voltage by the current value of the measurement current by the resistance calculating unit; (E) acquiring a reference resistance value Rref represented by the following formula (A) as a target value of calibration which is a target of the measured resistance value Rx. Reference resistance value Rref = Rs × Rt / Rz (A) where Rt is the resistance value of the selection resistance portion, and Rz is the resistance value of the entire series resistance portion.

  The resistance measuring device according to the present invention is a resistance measuring device for measuring the resistance of a measurement target, and a current supply unit for supplying a measurement current for supplying the measurement target, and the measurement target are generated in the measurement target A voltage measurement unit for measuring a voltage as a measurement voltage, a series resistance unit in which a plurality of setting resistors each having a preset resistance value are connected in series, and a base resistor having a preset base resistance value Rs And a current supply switching unit that causes the current supply unit to supply the measurement current to the base resistance of the reference resistor, and a reference resistor connected in parallel, and one of the plurality of setting resistors Alternatively, a measurement target switching unit that causes the voltage measurement unit to measure the voltage across the selection resistor, which is a continuous partial set resistance, as the measurement voltage by the voltage measurement unit, and the measurement voltage measured by the voltage measurement unit A resistance calculation unit that calculates a measured resistance value Rx by dividing it by the current value of the measurement current, and a reference resistance value Rref represented by the following equation (A), which is a target of the measured resistance value Rx And a calibration unit for acquiring the target value. Reference resistance value Rref = Rs × Rt / Rz (A) where Rt is the resistance value of the selection resistance portion, and Rz is the resistance value of the entire series resistance portion.

  According to these configurations, the measurement current is supplied by the current supply unit to the base resistance of the reference resistor, and the voltage generated across the base resistance is applied to the series resistance unit by the measurement current, and the application is performed. The voltage is divided by the selection resistor unit and measured as a measurement voltage by the voltage measurement unit. Furthermore, the measured voltage measured by the voltage measurement unit is divided by the current value of the measurement current by the resistance calculation unit to calculate the measured resistance value Rx. As a result, if the measurement result of the resistance measurement 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 a calibration target value. Also, from the equation (A), the reference resistance value Rref is smaller than the base resistance value Rs of the base resistance. In this case, since the resistance value is larger than the low resistance reference resistance value Rref to be obtained, and thus the readily available basic resistance can be used to obtain the reference resistance value Rref available for calibration, the low resistance It is easy to obtain the reference resistance value.

  Moreover, it is preferable to further include a selection unit that selects one or a part of the setting resistors of the plurality of setting resistors as the selection resistor unit.

  According to this configuration, the selection unit can select an arbitrary selection resistor unit. If the selection resistance portion can be selected, the resistance value Rz of the selection resistance portion in the formula (A) can be selected. As a result, the reference resistance value Rref can be changed.

  Moreover, it is preferable that the said calibration part calibrates the said resistance measurement apparatus so that the said measurement resistance value Rx may be closely approached to reference | standard resistance value Rref shown by following formula (A).

  According to this configuration, it is possible to adjust the resistance measurement accuracy of the resistance measurement device.

  Further, in the substrate inspection apparatus according to the present invention, the measurement target switching unit switches the supply destination of the measurement current by the current supply unit to the measurement target by the above-described resistance measurement device and the current supply switching unit. Testing the substrate to be measured based on the switching control unit that switches the measurement target of the measurement voltage by the voltage measurement unit to the measurement target, and the measured resistance value Rx calculated by the resistance calculation unit. And a substrate inspection unit.

  According to this configuration, it is possible to configure a substrate inspection apparatus that can easily obtain a low resistance reference resistance value to be used for calibration.

  Further, in the reference resistor according to the present invention, a series resistor unit in which a plurality of setting resistors each having a preset resistance value is connected in series is connected in parallel with a base resistor having a preset base resistance value Rs. The reference resistor main body, a pair of current input terminals connected to both ends of the base resistor for receiving the input of the measuring current, and at least three of connection points between the plurality of set resistors And a voltage measurement 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 base resistance of the reference resistor, and the voltage generated across the base resistance by the measurement current is the series resistance portion , And the applied voltage is divided by a plurality of set resistors, and the divided voltage is generated between at least three voltage measurement terminals. Since this voltage is divided by the measurement current to obtain the reference resistance value Rref represented by the equation (A), the reference resistor can be used as a reference device for giving the reference resistance value Rref. And from Formula (A), reference resistance value Rref is smaller than basic resistance value Rs of basic resistance. In this case, since the reference resistance value Rref can be obtained using a basic resistance which is larger in resistance than the low resistance reference resistance value Rref to be obtained and is therefore easily available, the reference resistance value of the low resistance is obtained. It is easy.

  Preferably, the base resistance and the plurality of set resistances have a temperature coefficient of resistance smaller than that of copper.

  This configuration provides a reference resistor with better temperature stability than a low resistance reference made of copper.

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

  According to this configuration, two of the plurality of voltage measurement terminals are selected to measure the voltage, and by dividing by the measurement current, the reference resistance value of the continuous value according to the manner of the two selection We can get Rref.

  With such a reference resistor, a method of calibrating a resistance measurement device, a resistance measurement device, and a substrate inspection device, it is easy to obtain a low resistance reference resistance value.

It is a block diagram which shows an example of a structure of the board | substrate inspection apparatus using the resistance measuring device which concerns on one Embodiment of this invention. It is a circuit diagram which shows an example of a structure of the reference resistor shown in FIG. It is explanatory drawing which shows an example of the look-up table previously memorize | stored in a memory | storage part. It is a block diagram which shows the example which applied the reference | standard resistor to the board | substrate inspection apparatus using the resistance measuring device by a 2 terminal measuring method. It is a block diagram showing an example of composition in the case of calibrating a substrate inspection device which does not have a reference resistor with a calibration method concerning one embodiment of the present invention. It is a flowchart which shows an example of the calibration method of the resistance measuring device which concerns on one Embodiment of this invention.

  Hereinafter, an embodiment according to the present invention will be described based on the drawings. FIG. 1 is a block diagram showing an example of the configuration of a substrate inspection apparatus 1 using a resistance measurement device according to an embodiment of the present invention. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, and abbreviate | omits the description.

  The substrate inspection apparatus 1 (resistance measurement apparatus) shown in FIG. 1 includes a reference resistor 3, a current supply unit CS, a voltage measurement unit 4, a current probe Pc1, a current probe Pc2, a detection probe Pv1, a detection probe Pv2, a switching circuit 6 A current supply switching unit, a measurement target switching unit), a selection unit 7, and a control unit 5 are provided. The substrate inspection apparatus 1 performs resistance measurement for substrate inspection, and thus corresponds to an example of a resistance measurement apparatus.

  FIG. 1 shows a state in which each probe of the substrate inspection apparatus 1 is in contact with the substrate A to be inspected. The substrate inspection apparatus 1 is configured to perform resistance measurement by a so-called four-terminal measurement method. The part except board inspection part 55 mentioned below from substrate inspection device 1 is equivalent to an example of resistance measuring device.

  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 substrate, a glass epoxy substrate, a flexible substrate, a ceramic multilayer wiring substrate, etc. -Luminescence) It may be an electrode plate for displays such as displays, a transparent conductive plate for touch panels, etc., and various substrates such as semiconductor wafers, semiconductor chips, semiconductor substrates such as CSP (Chip size package), etc. Good.

  Further, the substrate to be inspected may be a component built-in substrate (embedded substrate) in which electronic components such as semiconductor chips are embedded. 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, terminals and the like are formed on a substrate or an electronic component to be inspected.

  FIG. 1 illustrates a cross-sectional view of an interposer substrate for a semiconductor package as a 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. On the other surface of the substrate A, a plurality of outward electrodes A2 for connecting the semiconductor chip to the outside are formed.

  Each chip side electrode A1 and each outward electrode A2 are electrically connected by a wiring A3 (conductor) formed to penetrate through the thickness direction of the substrate A. The substrate inspection apparatus 1 measures and inspects the resistance value of each wiring A3. The wiring A3 corresponds to an example of an object to be measured. 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, for example, wire-like contacts having a diameter of about 100 μm to about 200 μm and having elasticity (flexibility). The current probes Pc1 and Pc2 and the detection probes Pv1 and Pv2 are formed of, for example, a metal or other conductor such as tungsten, high-speed steel (SKH), beryllium copper (Be-Cu) or the like.

  The tips of the current probe Pc1 and the detection probe Pv1 are in contact with the tip 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 tip side electrode A1.

  In FIG. 1, although the illustration is simplified and one probe is described for each of the probes Pc1, Pc2, Pv1 and Pv2, there may be cases where several hundreds to several thousand inspection points are set for one substrate, Several hundreds to several thousands of probes Pc1, Pc2, Pv1 and Pv2 may be provided corresponding to such a large number of inspection points.

  The current supply unit CS is a constant current circuit that flows a constant current. The current value Is of the measurement 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 measurement unit 4 measures the voltage between the detection probes Pv1 and Pv2 or the voltage of the selection resistance terminal of the reference resistor 3 described later. The voltage measurement unit 4 is configured using, for example, an analog-to-digital converter, a voltage dividing resistor, or the like. The voltage measurement unit 4 measures the voltage between the detection probes Pv1 and Pv2 selected by the switching circuit 6 as the measurement voltage Vx, or measures the voltage of the selection resistance terminal as the measurement voltage Vx, and displays data indicating the measurement voltage Vx Output to control unit 5.

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

  The reference resistor main body 31 includes a resistor Rstd (base resistor) and resistors R1 (first resistor), R2 (second resistor), R3 (third resistor), R4 (fourth resistor), R5 (fifth resistor) , R6 (sixth resistor), R7 (seventh resistor), R8 (seventh resistor), RA (the ninth resistor), and RB (the tenth resistor) are connected in series with a parallel circuit with the series resistor portion 32 It is done. The resistors R1, R2, R3, R4, R5, R6, R7, R8, RA, and RB correspond to an example of setting resistors.

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

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

  The switching circuit 6 can switch 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 can switch the connection destination of the voltage measurement unit 4 between the detection probes Pv 1 and Pv 2 and the selection unit 7.

  The switching circuit 6 includes, for example, a plurality of switches including switches 61a, 61b, 62a, 62b, 63a, 63b, 64a, 64b. These switches are various switching elements, such as semiconductor switches, such as a transistor, a relay switch, etc., for example. Each switch is turned on / 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 a reference It is connected to the terminal Ts1 of the resistor 3. The negative terminal (-) 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 a terminal of the reference resistor 3 Connected to Ts2.

  The positive terminal (+) terminal of the voltage measurement 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 is the selection unit 7 It is connected to the reference resistor 3 via The negative terminal (-) terminal of the voltage measurement 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 is the selection unit 7 It is connected to the reference resistor 3 via

  Thus, when the switches 61a and 62a are turned on and the switches 61b and 62b are turned off, the destination of the measurement current I is switched to the side of the wiring A3 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 side of the reference resistor 3, and calibration is possible. 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 target of the measurement voltage Vx by the voltage measurement unit 4 is switched to the wiring A3 side to be measured, and the resistance of the wiring A3 can be measured. Ru. On the other hand, when the switches 63a and 64a are turned off and the switches 63b and 64b are turned on, the measurement target of the measurement voltage Vx by the voltage measurement unit 4 is switched to the terminal side of the reference resistor 3 selected by the selection unit 7. , Can be calibrated. 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. Selection unit 7 selects two terminals among terminals T1 to T9 according to a control signal from control unit 5, and selects the selection resistance unit between the selected two terminals by connecting to switches 63b and 64b. . Hereinafter, two terminals located at both ends of the selection resistance portion are referred to as selection 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 central processing unit (CPU) that executes predetermined arithmetic processing, a random access memory (RAM) that temporarily stores data, a non-volatile storage device that stores a predetermined control program, and the like. It is a so-called microcomputer provided 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 drawing showing an example of the look-up table LUT stored in advance in the storage unit 56. As shown in FIG. The look-up table LUT shown in FIG. 3 corresponds to the selection resistance terminal and the selection resistance when the resistance values R ₁ and R ₂ are 10 Ω and the resistance values R _{3 to} R ₈ are 30 Ω in the reference resistor 3 shown in FIG. The resistance value Rt of the part is associated with the reference resistance value Rref.

  For example, the description “T3-T2: 10Ω” of the lookup table LUT means that the selection resistance terminals are 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 indicate that different reference resistance values Rref can be obtained depending on the difference between the resistance values Rs, Ra, and Rb. In the reference resistor 3 shown in FIG. 2, since the resistance values Rs, Ra, Rb are fixed values, only the portion corresponding to the type of the reference resistor 3 provided in the substrate inspection apparatus 1 is used as the lookup table LUT. You may make it memorize | store in the memory | storage part 56. FIG.

  The reference resistance value Rref, the resistance value Rs of the resistance Rstd, and the resistance value Rt of the selection resistance portion have a relationship substantially indicated by the following formula (A).

Reference resistance value Rref = Rs × Rt / Rz (A)
However, Rz is a resistance value of the whole series resistor portion _32, it is _{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 the case of type A, if the selection resistance terminal is the terminals T3 and T2, Rs = 3.3 mΩ, Rt = 10 Ω, and Rz = 330 Ω. Therefore, when substituted in equation (A), the reference resistance value Rref = 3. 3 mΩ × 10 Ω / 330 Ω = 0.1 mΩ, which matches the look-up table LUT.

  The switch control unit 52 switches the supply destination of the measurement current I by the current supply unit CS to the substrate A by the switches 61a, 61b, 62a, 62b when performing resistance measurement of the measurement object, and switches 63a, 63b, The measurement destination of the measurement voltage Vx by the voltage measurement unit 4 is switched to the substrate A by 64 a and 64 b. Hereinafter, this switching state is referred to as a measurement mode.

  When calibration of resistance measurement is performed, 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 (resistor Rstd) by the switches 61a, 61b, 62a and 62b. The switch 63a, 63b, 64a, 64b switches the measurement destination of the voltage measured by the voltage measurement 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.

  Thus, in the calibration mode, the current supply unit CS supplies the measurement current I to the resistor Rstd (base resistance) of the reference resistor 3 (step (b)), and the voltage across the selection resistor is a voltage The measurement unit 4 measures the voltage as a measurement voltage Vx (step (c)).

  In the present specification, “calibration” means the value (measurement resistance value Rx) indicated by the meter or measurement system and the value realized by the standard (reference resistance) according to the definition of “measurement terms” in JIS Z 8103: 2000. It means to establish the relationship between the value Rref) and does not necessarily include adjusting the substrate inspection apparatus 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 measurement unit 4 and the current value Is of the measurement current I (step d)).
Measured resistance value Rx = Vx / Is (1)

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

  The calibration unit 54 refers to the lookup table LUT stored in the storage unit 56, and acquires a reference resistance value Rref corresponding to the selected resistance terminal selected by the selection unit 7 (step (e)). Since the reference resistance value Rref of the look-up table LUT is the value represented by equation (A), the calibration unit 54 refers to the look-up table LUT to obtain the reference resistance value represented by equation (A). Rref can be obtained as a target value of calibration which is a target of the measured resistance value Rx. The principle by which the reference resistance value Rref which is the target value of calibration is obtained by the equation (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 lookup table LUT. The calibration unit 54 may obtain the reference resistance value Rref by actually performing the calculation of Equation (A).

  In addition, the calibration unit 54 may obtain the reference resistance value Rref which is set in advance or input to the substrate inspection apparatus 1 from the outside as it is. Then, the calibration unit 54 refers to the look-up table to obtain the selected resistance terminal corresponding to the reference resistance value Rref, and causes the selection unit 7 to select the voltage measurement terminal corresponding to the selected resistance terminal. You may

  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 (measured resistance value Rx) indicated by the meter or measurement system and the standard. Steps (b) to (e) correspond to calibration, since the relationship between the value (reference resistance value Rref) and the value to be calculated (the reference resistance value Rref) are associated and determined.

  The calibration unit 54 adjusts the current supply unit CS, the voltage measurement unit 4, or a current measurement unit that measures the actual current value Is of the measurement current I so that the measured resistance value Rx approaches the reference resistance value Rref. Then, the step of correcting the error may be performed.

  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 obtained for each selection resistance unit and the reference A calibration table for correlating the resistance value Rref or a calibration table for correlating the difference between the measured resistance value Rx and the reference resistance value Rref to the measured resistance value Rx may be created and stored in the storage unit 56. Then, after calculating the measured resistance value Rx in the measurement mode, the resistance calculation unit 53 refers to the calibration table and determines the measured resistance value Rx based on the reference resistance value Rref or the difference associated with the measured resistance value Rx. You may make it correct | amend.

  Further, the calibration unit 54 causes calibration information including the measured resistance value Rx and the reference resistance value Rref to be displayed, for example, on a display device not shown, or transmitted outside using a communication circuit not shown, etc. May be notified to the maintenance worker or the user. The maintenance worker or the like who has been notified of the calibration information can adjust the substrate inspection apparatus 1 so that the measured resistance value Rx approaches the reference resistance value Rref, based on the notified calibration information.

  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 in the measurement mode. Specifically, the board inspection unit 55 compares the determination reference value RR stored in advance in the storage unit with the measured resistance value Rx, and when the measured resistance value Rx is smaller than the determination reference value RR, the wiring A3 When the measured resistance value Rx is equal to or greater than the judgment reference value RR, the wiring A3 is judged to be defective.

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

  In the calibration mode, the switch 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 to the resistor Rstd. Since the resistor Rstd and the series resistor 32 are connected in parallel, strictly speaking, the measurement current I is divided into the resistor Rstd and the series resistor 32. However, if the resistance value Rz of the series resistance portion 32 is sufficiently larger than the resistance value Rs of the resistance Rstd, the current flowing through the series resistance portion 32 can be ignored. Therefore, all the measuring currents I will be described as flowing through the resistor Rstd.

  For example, in the case of type A shown in the look-up table LUT, the resistance value Rz of the series resistor 32 is 330Ω, the resistance value Rs of the resistor Rstd is 3.3 mΩ, and Rz: Rs = 100000: 1. Since the current value flowing to Rz and Rs is an inverse ratio of the resistance ratio, the current flowing to the series resistance portion 32 is 1 / 100,000 of the current flowing to the resistor Rstd and can be substantially ignored.

When the measurement current I of the current value Is flows through the resistor Rstd, the voltage Vs across the resistor Rstd is Vs = Is × Rs. Since the resistor Rstd and the series resistor 32 are connected in parallel, the voltage Vs is also applied to the series resistor 32. Then, the measurement voltage Vx generated between the two selection resistance terminals is expressed by the following equation (2) by the division of the resistance value Rz of the series resistance portion 32 and the resistance value Rt of the selection resistance portion.
Measurement voltage Vx = Vs × (Rt / Rz) = Is × Rs × Rt / Rz (2)

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

Measurement voltage Vx = Is × Rref (3)
It becomes.

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 measurement voltage Vx generated between the two selection resistance terminals is measured by the voltage measurement unit 4. From the measurement voltage Vx measured by the voltage measurement unit 4, the resistance calculation unit 53 calculates the measurement resistance value Rx using the above equation (1). Here, when equation (3) is substituted into equation (1), the following equation (4) is obtained.
Measured resistance value Rx = Vx / Is = (Is × Rref) / Is = Rref (4)

  From the equation (4), in the calibration mode, the measured resistance value Rx calculated by the resistance calculation unit 53 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 relative to the resistance Rstd (base 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 selection resistance unit as the measurement voltage Vx by the voltage measurement unit 4, and the resistance calculation unit 53 By performing step (d) of calculating the measured resistance value Rx by dividing the measured voltage Vx by the current value Is of the measurement current I, the reference resistor 3 equivalently has the reference resistance value Rref. 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 Since the reference resistance value Rref shown by A), that is, the reference resistance value Rref shown by the look-up table LUT should match, the calibration unit 54 can use the reference resistance value Rref as a calibration target value.

  Here, according to 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 resistor Rstd can be obtained by the voltage division ratio (Rt / Rz). .

  For example, as in the 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, A resistance value easy to use, for example, a resistance of 10 to 120 Ω can be used. As a result, it is possible to configure the reference resistor 3 using one low-resistance 3.3 mΩ resistor Rstd and a resistor in the readily available resistance value range.

  Also, 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 3.3 mΩ resistance Rstd. It can be obtained by combining the resistances R1 to R8, RA, RB, and the resistance Rstd of various resistance values, so it becomes easy to obtain the low resistance reference resistance value Rref.

  Also, low resistance special resistors such as 0.2 mΩ are not only difficult to obtain, but also likely to be expensive if available. On the other hand, the resistors R1 to R8, RA, RB, Rstd are likely to be more readily available and less expensive than special resistors such as 0.2 mΩ, so they are more likely to be used than when such special resistors are used. There is a possibility that the cost of the reference resistor 3 can be reduced.

  Further, the reference resistor 3 includes a plurality of voltage measurement terminals T1 to T9, and a plurality of reference resistance values Rref can be obtained by selecting a selection resistance terminal from among these. Therefore, it is not necessary to provide a plurality of reference resistors having different resistance values, and the convenience is improved. Also, there is a possibility that the reference resistor 3 can be lower in cost than providing a plurality of reference resistors.

  For example, in types A to E shown in FIG. 3, by increasing the resistance value Rs by 10 times, in type A, reference resistance values Rref in 0.1 mΩ increments are obtained from 0.1 mΩ to 2.0 mΩ, In B, the reference resistance value Rref in 1 mΩ steps is obtained from 1 mΩ to 20 mΩ, and in the following types C, D and E, a 10-fold larger reference resistance value Rref is obtained, and the desired reference resistance is obtained simply by changing the resistance value Rs. Since the value Rref is obtained, the convenience is high.

Thus, the reference resistor 3 from which the reference resistance value Rref of continuous values is obtained is 10 Ω × N of the resistance values R ₁ and R ₂ of the resistors R ₁ and R _2, and the resistance values R _{3 to} R ₈ of the resistors R _{3 to} R _8. Is 30Ω × N, resistance Ra of resistor RA is 10Ω × N, resistance Rb of resistor RB is 120Ω × N, N is a natural number, and resistance Rs of resistor Rstd is 3.3mΩ + 3.3mΩ × 10 × M, M Is obtained by making it an integer of 0 or more.

In addition, when copper is processed to produce a reference resistor, copper has a large temperature coefficient of resistance, which causes a change in resistance due to temperature change, resulting in unstable resistance. On the other hand, in the case of the reference resistor 3, it can be made by combining a commercially available resistor having a resistance temperature coefficient much smaller than that of copper without using copper. A much more stable reference resistance can be easily obtained. For example, while the temperature coefficient of copper is 0.00393 [1 / ° C.], for example, in the case of MPP series ultra-precision chip resistors manufactured by Alpha Electronics, the temperature coefficient of resistance is about 0.2 × 10 ⁻⁶ / ° C. For example, in the case of low resistance metal plate resistor ERJM03N manufactured by Panasonic Corporation, the temperature coefficient of resistance is approximately 100 × 10 ⁻⁶ / ° C.

  In addition, since small chip resistors are commercially available, miniaturization is easier than when copper resistors are used. In addition, since it is sufficient to obtain a commercially available resistor, there is a high possibility that lead time and processing cost will be cheaper than processing copper.

  In addition, although the example provided with the reference resistance 3 in the board | substrate inspection apparatus 1 which measures resistance by a four-terminal measurement method was shown, for example, as shown in FIG. 4, one probe instead of current probe Pc1 and detection probe Pv1. Even in the case of the substrate inspection apparatus 1a which is equipped with Pr1 and equipped with one probe Pr2 instead of the current probe Pc2 and the detection probe Pv2 and which performs a two-terminal measurement method that combines current supply and voltage measurement with one probe. , Calibration by the reference resistor 3 can be performed.

  Further, the reference resistor 3 does not necessarily have to be incorporated in the substrate inspection device 1 or the resistance measurement device. For example, as shown in FIG. 5, a substrate inspection apparatus 1b or a resistance measurement apparatus that performs resistance measurement by a four-terminal measurement method and does not include the reference resistor 3, the switching control unit 52, and the calibration unit 54 Alternatively, it is possible to calibrate the resistance measuring device by the method of calibrating 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, Pc2 are brought into contact with the terminals Ts1, Ts2 of the reference resistor 3 to measure from the current supply portion CS. The current I is supplied (step (b)), the detection probes Pv1 and Pv2 are brought into contact with the selection resistance terminal of the reference resistor 3, and the voltage measurement unit 4 measures the measurement voltage Vx (step (c)) The measured resistance value Rx may be calculated by the unit 53 (step (d)), and the maintenance worker may be notified of this. The maintenance worker or the like acquires the reference resistance value Rref corresponding to the selected resistance terminal by referring to the look-up table LUT (step (e)), and compares the measured resistance value Rx with the substrate inspection apparatus. It is possible to calibrate 1b or the resistance measuring device.

  FIG. 6 is a flowchart showing an example of a method of calibrating a resistance measuring device according to an 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 a resistance measuring device such as the substrate inspection device 1 or 1a, or as shown in FIG. Is disposed outside the resistance measuring apparatus such as the substrate inspection apparatus 1b as a measurement target.

  Next, the measuring current I is supplied to the resistor 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, an aspect in which the measuring current I is supplied to the resistor Rstd by the internal wiring in the resistance measuring device such as the substrate inspection device 1 or 1a, or Thus, an aspect is provided in which the current is supplied through the current probes Pc1 and Pc2 included in the resistance measurement device such as the substrate inspection device 1b.

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

  Next, the voltage between both ends of the selection resistance portion is measured by the voltage measurement portion 4 as a measurement voltage Vx (step (c)). In the step (c), as shown in FIG. 1 and FIG. 4, the voltage measurement unit 4 is connected to both ends of the selection resistance unit via internal wiring in the resistance measurement device such as the substrate inspection device 1 or 1a. A mode of measuring the voltage Vx and a mode of measuring the measurement voltage Vx by bringing the detection probes Pv1 and Pv2 included in the resistance measuring device such as the substrate inspection apparatus 1b into contact with the selection resistance terminal as shown in FIG.

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

  Next, the reference resistance value Rref represented by the formula (A) is acquired as a calibration target value that is a target of the measured resistance value Rx (step (e)). In the step (e), a mode in which the calibration unit 54 such as the substrate inspection apparatus 1 or 1a as shown in FIGS. 1 and 4 acquires the reference resistance value Rref, or as shown in FIG. A reference resistor 3 is connected as a measurement target to a resistance measuring apparatus such as a substrate inspection apparatus 1b which does not include the calibration unit 54, and the current probes Pc1 and Pc2 and the detection probes Pv1 and Pv2 are brought into contact with each other. The reference resistance value Rref represented by the equation (A) with reference to the look-up table LUT, ie, the reference resistance value Rref corresponding to the selected resistance terminal with which the detection probes Pv1 and Pv2 are in contact It includes an aspect of acquiring as a target value of calibration which is a target.

  As described above, according to the steps (a) to (e), it is possible to obtain the reference resistance value Rref that is the target value (reference value) of calibration using the reference resistor 3.

  In addition, although the example which uses ten resistance of resistance R1-R8, RA, and RB as setting resistance was shown, the setting resistance should just be two or more. If there are at least two setting resistances, the effect of the resistance voltage division is obtained in the above equation (2) by setting two total resistance values as Rz and the resistance value of the selection resistance portion selected from two as Rt. The equation (A) can thus be applied. As a result, since it is possible to obtain a reference resistance value Rref smaller than the resistance Rstd, it becomes possible to configure a reference resistor which is easy to obtain a low resistance reference resistance value.

  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 setting 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 selection resistor parts.

  Moreover, the board | substrate inspection apparatus 1 and 1b may not be provided with the selection part 7, and the selection resistance terminal (selection resistance part) may be fixed to the switch circuit 6, and may be connected.

  Further, the temperature coefficient of resistance of the resistors R1 to R8, RA, RB, Rstd is not necessarily limited to an example smaller than copper. Even if the resistance temperature coefficient of the resistors R1 to R8, RA, RB, Rstd is higher than copper, it is possible to obtain a reference resistance value Rref smaller than the resistor Rstd, and thus obtain a low resistance reference resistance value. It is possible to construct a reference resistor that is easy to do.

  Further, the substrate inspection apparatus 1, 1 a, 1 b may be configured as a resistance measurement apparatus that does not include the substrate inspection unit 55.

1, 1a, 1b Substrate inspection device (resistance measuring device)
3 Reference Resistor 4 Voltage Measurement 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 substrate inspection unit 56 storage units 61a, 61b, 62a, 62b switches (current supply switching unit)
63a, 63b, 64a, 64b switches (measurement object switching unit)
A Substrate A1 Chip side electrode A2 Outward electrode A3 Wiring (target of measurement)
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 (setting resistance)
RR judgment reference value Rref reference resistance value Rstd resistance (base resistance)
Rs resistance (resistance of Rstd)
Rt resistance value (resistance value of selection resistance section)
Rx measured resistance value Rz resistance value (resistance value of the whole series resistance section)
T1 to T9 terminals (terminals for voltage measurement)
Ts1 and Ts2 terminals (current input terminals)
Vs voltage (voltage across Rstd)
Vx measurement voltage

Claims (8)

A current supply unit for supplying a measurement current to be supplied to a measurement object, a voltage measurement unit for measuring a voltage generated in the measurement object, and a measurement voltage measured by the voltage measurement unit as a current of the measurement current A calibration method of a resistance measuring device, comprising: a resistance calculating unit that calculates a resistance value by dividing by a value,
(A) Prepare a reference resistor in which a series resistance section in which a plurality of setting resistances each having a preset resistance value is connected in series and a base resistance having a preset base resistance value Rs are connected in parallel The process to
(B) causing the current supply unit to supply the measurement current to the base resistance of the reference resistor;
(C) causing the voltage measuring unit to measure the voltage across the selection resistor, which is one or a continuous portion of the plurality of setting resistors, as the measurement voltage;
(D) calculating the measured resistance value Rx by dividing the measured voltage by the current value of the measurement current by the resistance calculation unit;
(E) acquiring a reference resistance value Rref represented by the following formula (A) as a target value of calibration which is a target of the measured resistance value Rx: a calibration method of a resistance measurement device.
Reference resistance value Rref = Rs × Rt / Rz (A)
However, Rt is a resistance value of the selection resistance portion, and Rz is a resistance value of the entire series resistance portion. A resistance measuring device for measuring the resistance of a measurement target,
A current supply unit for supplying a measurement current for supplying the measurement object;
A voltage measurement unit for measuring a voltage generated in the measurement object as a measurement voltage;
A series resistor unit in which a plurality of setting resistors each having a preset resistance value are connected in series, and a reference resistor in which a base resistor having a preset base resistance value Rs is connected in parallel;
A current supply switching unit that causes the current supply unit to supply the measurement current to the base resistance of the reference resistor;
A measurement target switching unit that causes the voltage measurement unit to measure a voltage between both ends of a selection resistance unit that is one or a continuous set resistance of the plurality of setting resistances as the measurement voltage;
A resistance calculation unit that calculates a measured resistance value Rx by dividing the measurement voltage measured by the voltage measurement unit by the current value of the measurement current;
A calibration unit configured to obtain a reference resistance value Rref represented by the following formula (A) as a calibration target value that is a target of the measurement resistance value Rx.
Reference resistance value Rref = Rs × Rt / Rz (A)
However, Rt is a resistance value of the selection resistance portion, and Rz is a resistance value of the entire series resistance portion.   The resistance measuring apparatus according to claim 2, further comprising: a selection unit that selects one or a part of the setting resistances among the plurality of setting resistances as the selection resistance unit.   The resistance measuring apparatus according to claim 2 or 3, wherein the calibration unit calibrates the resistance measuring device such that the measured resistance value Rx approaches a 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 sets the measurement target of the measurement voltage by the voltage measurement unit as the measurement target A switching control unit for switching;
And 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 resistor main body portion in which a series resistance portion in which a plurality of set resistances each having a preset resistance value are connected in series and a base resistance having a preset base resistance value Rs are connected in parallel;
A pair of current input terminals connected to both ends of the base resistor for receiving an input of a measurement current;
A reference resistor comprising: voltage measurement terminals respectively connected to at least three of connection points between the plurality of setting resistors and for measuring a voltage corresponding to a reference resistance value Rref.   The reference resistor of claim 6, wherein the base resistance and the plurality of set resistances have a resistance temperature coefficient smaller than copper. The series resistor unit includes first, second, third, fourth, fifth, sixth, seventh, eighth, ninth and tenth resistors in this order as the plurality of setting resistors,
The resistance of the first and second resistors is 10Ω × N, the resistance of the third to eighth resistors is 30Ω × N, the resistance of the ninth resistor is 10Ω × N, and the resistance of the tenth resistor is 120 Ω × N, N is a natural number,
The base resistance value Rs is 3.3 mΩ + 3.3 mΩ × 10 × M, and M is an integer of 0 or more,
The voltage measurement terminal is connected to the connection point between the first to ninth resistances and the end of the first resistance opposite to the second resistance. Reference resistor described.

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