JP4361259B2 - Static electricity countermeasure system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention is a device, line or property.(Hereinafter referred to as “devices”)Preventing static electricity disastersforCountermeasure against static electricitysystemAbout.
[0002]
[Prior art]
  Conventionally, malfunctions caused by static electricity in natural phenomena, various social activities, various industries, etc.Electrostatic failure, electrostatic disaster, electrostatic hazard disaster orAlthough it is sometimes expressed as an electrostatic disaster hazard, in this specification, it is collectively referred to as an “electrostatic hazard” (ESD hazard: Electrostatic Discharge Hazard).Call.
[0003]
  The simplest example is a system consisting of a charged object (hereinafter simply called “charged body”) and a device.aboutexplain. However,In the following explanationThe above-mentioned electrostatic failure may be abbreviated as “static failure”.
  It is known that when a static electricity of a charged body is discharged to a device, an electrostatic failure occurs when a discharge voltage corresponding to the discharge energy input to the device is larger than the net electrostatic resistance of the device. Here, the “net static resistance” of the device is a voltage that is actually input to the device, unlike the resistance against the voltage of an ESD (Electrostatic Discharge) evaluation test apparatus published by each manufacturer.
  In addition, the discharge voltage received by the device may be a source of causing electrostatic failure in the device, and is an index as to whether or not electrostatic failure occurs in the device. In the present specification, this discharge voltage is referred to as “failure generating ability” (“disaster generating ability” or “ESD hazard potential”).Call.
[0004]
  Depending on the environment in which the device is actually placed, there are various ways in which electrostatic damage can occur.TheFor example, in a factory that manufactures devices, (1) use conductive flooring, (2) workers wear special work clothes, wear wrist straps, (3) install static eliminators, etc. Of ESD hazard countermeasures. In order to efficiently implement such ESD hazard countermeasures, it is necessary to correctly recognize the behavior of environmental static electricity surrounding the device.
[0005]
  Conventionally, a method of measuring the potential of a charged body, which is a source of static electricity, with an electrostatic measuring device such as a surface potential measuring device has been used. In this method, the electrostatic field potential is measured by bringing a static electricity meter closer to a charged body. This measured potential corresponds to the electrostatic energy that the charged body potentially has. However, the charged body rarely releases all electrostatic energy due to discharge, and usually a part thereof is released. Further, when the charged body and the device are not in contact, a part of the released energy is consumed in the air between the charged body and the device. That is, the discharge energy actually received by the device is smaller than the electrostatic energy of the charged body, and they are different. As a result, the conventional ESD meter cannot measure the ESD hazard potential of static electricity.
  On the other hand, the present applicant has previously devised an electrostatic discharge measuring device that reproduces and measures the ESD hazard potential (Japanese Patent Application No. 2002-297123). This measuring device can measure the voltage actually input to the device regardless of whether the type of the charged body is a metal or an insulator.
[0006]
  On the other hand, the electrostatic resistance of a device is conventionally required as the resistance against a voltage applied by an ESD evaluation test apparatus. However, the value of the conventional electrostatic resistance varies depending on the ESD evaluation test apparatus and its manufacturer, and the relationship with the actual destructive force of electrostatic discharge is not clear. Therefore, this is called “apparent static resistance” and is distinguished from “net static resistance”.
  Net static resistance is calculated by converting the apparent static resistance into net resistance in consideration of the transfer function of the ESD evaluation test device.belowThis can be obtained by measuring the damage voltage of the device by the method disclosed in Non-Patent Document 1.
[0007]
  Conventionally, there are various evaluation indexes for antistatic materials and antistatic materials.
  The antistatic material is a flooring material, footwear, a wrist strap, or the like made of a conductive material, and provides a path through which, for example, a human body is charged with electric charges. Conventionally, such antistatic materials have antistatic capabilities such as flooring surface resistivity, flooring ground resistance, shoe grounding resistance (human body + shoes), and human body grounding resistance (human body + shoes). + Floor), and human body charging voltage are measured and evaluated by the magnitude of human body potential and resistance between grounds.
  The antistatic material is, for example, a cloth material / packaging material composed of a conductive material or a shield material, and has an antistatic function. Conventionally, electrostatic capacity is evaluated by the decay rate or half-life of electric charge for cloth materials and packaging materials, and by frictional charging for packaging materials.
[0008]
  The static eliminator is roughly classified into two types, a bar type and a blower type. However, there have been various indexes for the static elimination capability, and it has not been clearly determined how much it is effective for actual electrostatic discharge as well as confuse the user.
  For example, there are two types of evaluation indexes for the static elimination capability of a bar-type static elimination device. One is a static elimination current applied to a pseudo-charged plate to which a DC high voltage is applied, and the other is to check the performance in an actual place of use with an electrostatic meter.
  In addition, there are the following three evaluation indexes for the charge removal capability of the blower type device. (1) An ion flow that flows into a measurement electrode that is placed in front of an ion outlet and to which a bias voltage is applied, (2) a potential decay time of a charged measurement electrode, and (3) a metal electrode that is charged with direct current using a wire mesh The current that shields and flows into the shield.
[0009]
  As described above, the ESD hazard potential of the charged body actually exerted on the device, the electrostatic resistance of the device, the antistatic capability of the antistatic material, the antistatic capability of the antistatic material, and the static eliminating capability of the static eliminator have conventionally been As a result, the system has not been treated in a unified manner, and therefore it has not been possible to implement an appropriate countermeasure against static electricity on the system as a system.
[0010]
[Non-Patent Document 1]
  Norio Murasaki, Yasuaki Enomoto, “Quantification of ESD Resistance Evaluation of Devices”, IEICE Technical Report, The Institute of Electronics, Information and Communication Engineers, March 2002, SSS 2001-33
[0011]
[Problems to be solved by the invention]
  In view of such a background, the present invention efficiently disposes antistatic materials, antistatic materials, and static eliminators so as to prevent electrostatic troubles such as devices.Static electricity countermeasure systemThe purpose is to provide.
[0012]
[Means for Solving the Problems]
  The present invention is an electrostatic countermeasure system for preventing an electrostatic failure caused by discharge of a charged object to a device or the like to be subjected to electrostatic countermeasures,
  An antistatic material that constitutes a path for leaking electric charges carried by the object to the ground, an antistatic material having an antistatic function such as the device, and a static eliminator that neutralizes static electricity such as the device.Arranged and configured,
  Discharge voltage value received by the device when the object is discharged to the deviceIs defined as the ability of the object to cause a disaster.,
  The discharge voltage actually input from the object to the device or the like when an electrostatic failure disaster occurs in the device or the like is defined as the net static resistance of the device or the like.,
  The difference between the disaster occurrence potential of an object located on the static electricity prevention material and the obstacle disaster occurrence capability of an object located on the static electricity prevention material before taking static electricity countermeasures is calculated., Defined as the antistatic ability of the antistatic material,
  The difference between the disaster prevention ability of the antistatic material before the antistatic processing and the disaster occurrence ability of the antistatic material after the antistatic processingIs defined as the antistatic capability of the antistatic material.,
  The difference between the disaster occurrence force of the object to be neutralized and the failure occurrence force of the object after the static eliminator has neutralized the static electricity of the objectIs defined as the charge removal capability of the charge removal device,
  The antistatic material, the antistatic material and the static eliminator are:For antistatic ability of the antistatic material, antistatic ability of the antistatic material and static elimination ability of the static eliminatorOn the basis of,After the countermeasure is taken,Selected to be less than the net static resistance of the device etc.It is characterized by that.
[0013]
  In the present inventionFor example, an electronic device or the like is a target device to be subjected to static electricity countermeasures.In addition to the equipment ofIncludes production lines for manufacturing processes, assembly processes, inspection processes, etc., and properties related to textiles, petroleum, chemicals, powders, copying machines, aircraft, etc. The charged object includes a human body.
  The failure occurrence power of an object is the electrostatic failure occurrence force of an object, and is defined as a discharge voltage value received by the device or the like when the object is discharged to the device or the like.
  The measuring device used to measure the obstacle power of an object isFor example,This is an electrostatic discharge measuring device disclosed in Japanese Patent Application No. 2002-297123 by the present applicant. In this device, the discharge path from the electrode to the ground electrode is configured to substantially match the input impedance of the device or the like that is to be subjected to static electricity countermeasures.
  Therefore, the discharge from the object to the device or the like can be reproduced by bringing the object into contact with the electrode of the apparatus and discharging the object to the electrode. Then, the voltage value of the electrode obtained at this time is set as the “disaster disaster occurrence power” of the object.
[0014]
  The static electricity countermeasure material constitutes a path for leaking the electric charge carried by the object to the ground. For example, floor materials, shoes, wrist straps and the like correspond to this.
  In order to obtain the antistatic capability of such an antistatic material, first, the above-described electrostatic discharge measurement power of the object when the material before the antistatic measure is applied to the charged object is measured. Measure with the instrument. Next, the failure occurrence ability of the object when the antistatic material is applied to the object is measured by the above-described electrostatic discharge measuring device. At this time,Static electricity prevention materialsFor example, in the case of floor materials and shoes, a human body (measured person) is positioned thereon, and in the case of a wrist strap, the human body (measured person) wears it and measures. Then, the difference between before and after taking countermeasures is obtained and used as the antistatic ability of the antistatic material.
[0015]
  The antistatic material has an antistatic function of a device or the like, for example, work clothes, packaging materials, and the like.
  In order to obtain the antistatic capability of the antistatic material, first, the failure occurrence ability of the material before the antistatic processing is measured by the electrostatic discharge measuring device. Next, the failure occurrence ability of the antistatic material when the antistatic material is applied to the device or the like is measured by the above-described electrostatic discharge measuring device. At this time, for example, if a person wears work clothes, a person wears it, and if it is a packaging material, the device or the like is wrapped and measured. Then, the difference between before and after the material is subjected to antistatic processing is obtained to determine the antistatic ability of the antistatic material.
  In order to obtain the static elimination capability of the static eliminator, first, the failure occurrence ability of the object to be neutralized is measured by the electrostatic discharge measuring device. Next, the failure occurrence ability of the object after the static eliminator has neutralized the static electricity of the object is measured by the above-described electrostatic discharge measuring device. And the difference of the fault disaster generating power before static elimination and after static elimination is calculated | required, and it is set as the static elimination capability of a static elimination apparatus.
[0016]
  In addition, “net static resistance” of a device or the like is defined as a discharge voltage that is actually input from an object to the device or the like when an electrostatic failure occurs in the device or the like.
  For example, the net static resistance of a device is different from the voltage resistance (apparent static resistance) of an ESD evaluation test apparatus, and the apparent static resistance is converted into a net resistance in consideration of the transfer function of the ESD evaluation test apparatus. Or by measuring the damage voltage of the device.
[0017]
  Electrostatic countermeasure system of the present inventionThenBased on the anti-static ability of the anti-static material, the anti-static ability of the anti-static material and the anti-static ability of the static eliminator,The ability of an object to cause a disaster after taking countermeasures is greater than the net static resistance of devices, etc.To be smallerSelection of antistatic materials, antistatic materials and static eliminatorsIs done. At this time, static electricity failure does not occur in the device or the like.
[0018]
  Also,In the anti-static system of the present invention, the anti-static material of the anti-static material, the anti-static material of the anti-static material, and the static eliminating device of the static eliminator.SaidEvaluated with the same physical quantities as the ability of an objectIs, They can be selected and compared with each other.
[0019]
  The antistatic capability of the antistatic material, the antistatic capability of the antistatic material, and the static elimination capability of the static eliminator have been conventionally evaluated by various indicators such as a resistance value and a current value.In the present inventionAccording to the static electricity countermeasure capacity of static electricity countermeasure materials, static electricity countermeasure capacity of antistatic materials, and static electricity removal capacity of static eliminator as a voltage value of the same dimension as fault disaster occurrence power (voltage value). Can do.
  In addition, the evaluation index of static electricity countermeasures for the entire system, including net static resistance of devices, etc.Can be unified to voltage valueTherefore, unnecessary confusion can be prevented and the cost for countermeasures against static electricity can be easily estimated.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
  Static electricity countermeasures according to this embodimentsystemIn this case, an antistatic material, an antistatic material, and a static eliminator are appropriately provided for a device to be subjected to antistatic measures. Here, the material for preventing static electricity constitutes a path for leaking electric charges carried by an object to the ground, and examples thereof include floor materials, shoes, socks, and wrist straps. Further, the antistatic material has an antistatic function of an apparatus or the like, and examples thereof include work clothes, packaging materials, and rugs on a work table.
[0021]
  First, this implementationIn formDisability to be used (hereinafter may be abbreviated as failure occurrence), antistatic ability of antistatic materials, antistatic ability of antistatic materials,as well asThe definition of the charge removal capability of the charge removal device will be described below.
[0022]
(Definition of failure generation ability)
  The obstacle generation force (ESD hazard potential) of an object is defined as a discharge voltage value received by the device or the like when the object discharges to a device or the like to be subjected to static electricity countermeasures. And this discharge voltage value shall be measured by the electrostatic discharge measuring device mentioned later. Here, the object is present in a production line or an assembly line, for example, a human body or a production apparatus.
[0023]
(Definition of anti-static ability of anti-static materials)
  The static electricity countermeasure capability of the static electricity countermeasure material is defined as the difference between the failure generation force of the object on the material before the static electricity countermeasure is taken and the failure generation force of the object located on the static electricity prevention material. In order to obtain the static electricity countermeasure capability of the static electricity countermeasure material, first, the failure generation force of the object is measured by a static electricity discharge measuring device described later on the material before the static electricity countermeasure is taken under a predetermined condition. Then, the failure generation force of the object on the antistatic material is measured by the above-described electrostatic discharge measuring device. At this time, for example, when human body charging is intended, if socks, wrist straps, etc. are materials for countermeasures against static electricity, the measurement is performed with the subject wearing them. Moreover, the said material shall be earth | grounded. Then, the difference between the failure generation force of the person to be measured on the material before taking countermeasures against static electricity and the failure generation force of the person to be measured on the material for countermeasures against static electricity is obtained. This difference is the antistatic capability of the antistatic material.
[0024]
(Definition of antistatic material's ability to prevent static electricity)
  Examples of the antistatic material include work clothes worn by a human body (a person to be measured), a rug on which the device is placed, or a packaging material for packaging the device. In order to obtain the antistatic ability of the antistatic material worn by the human body, first, the failure generating power of the material before the antistatic processing is measured by an electrostatic discharge measuring device described later. Next, for example, the fault generation force of the antistatic material worn by the measurement subject is measured by the above-described electrostatic discharge measuring device. The above materials shall be grounded. The difference between the failure generating ability of the material before the antistatic processing and the failure generating ability of the antistatic material is the antistatic ability of the antistatic material.
  On the other hand, for example, in order to obtain the static electricity countermeasure capability of an antistatic material for a device, first, the device is packaged or placed with the material before the antistatic processing, and the failure generation force of the material is measured by an electrostatic discharge measuring device described later. Measure with Similarly, the failure generating ability of the antistatic material in which the device is packaged or placed is measured by the above-described electrostatic discharge measuring apparatus. The difference between the two becomes the antistatic ability of the antistatic material.
[0025]
(Definition of static elimination capability of static elimination device)
  The neutralization capability of the static eliminator is defined as the difference between the failure generation force of the object to be neutralized and the failure generation force of the object after being neutralized by the neutralization device. The electrostatic discharge measuring device described above is used to determine the obstacle generation force of an object.
[0026]
  next,BookStatic electricity countermeasures according to the embodimentsystem'sAs a specific example, a case where a device is handled in a clean room will be described.
  FIG. 1 is an explanatory diagram for explaining an assembly process of a device in a clean room. On a work table 2 in the clean room 1, a device 3 to be subjected to countermeasures against static electricity is placed. The device 3 is, for example, a semiconductor integrated circuit.
  On the work table 2, for example, an assembly apparatus 4 for assembling the device 3 is disposed as a charged body that discharges static electricity to the device 3. Further, it is assumed that the worker 5 exists as another charged body.
[0027]
  The antistatic material includes, for example, an antistatic floor material 8, an antistatic shoe 9, and a wrist strap 10. In addition, the antistatic material is composed of, for example, work clothes 11 which is clothes for countermeasures against static electricity. Here, the antistatic material and the antistatic material are provided as a countermeasure against static electricity by the worker 5 as a charged body, and the static eliminator 12 is provided as a countermeasure against static electricity by the assembling apparatus 4 as a charged body. And
[0028]
  Hereafter, countermeasures against static electricity of this embodimentsystem(1) Device manufacturer's response, (2) Static electricity countermeasure material and antistatic material dealer's response, (3) Static eliminator manufacturer's response, (4) On-site static electricity countermeasures Details will be described separately for each of the following items: (5) On-site static electricity countermeasure procedure, (6) Configuration and operation of electrostatic discharge measuring device, and (7) Configuration and operation of checker.
[0029]
(1) Device manufacturer response
  The device manufacturer shall measure the net static resistance of the device in advance. The “net static resistance” of this device is different from the voltage resistance (apparent static resistance) of the ESD evaluation test equipment. When an electrostatic failure occurs in the device, it is actually from the charged body to the device. It is defined as an input discharge voltage. The net static resistance is determined by converting the apparent static resistance to the net resistance in consideration of the transfer function of the ESD evaluation test apparatus or by measuring the damage voltage of the device. The manufacturer of the device informs the user of the obtained net static electricity resistance value (voltage value) through the device catalog and specifications.
[0030]
(2) Dealers of antistatic materials and antistatic materials dealers
  Distributors purchase anti-static flooring materials, anti-static shoes, wrist straps, etc. from manufacturers of anti-static materials, and work clothes from anti-static materials manufacturers. Find it as follows.
  For example, a dealer prepares an electrostatic discharge measuring device to be described later, and selects an electrode of the electrostatic discharge measuring device according to the input impedance of a device to be subjected to static electricity countermeasures.
  First, a person to be measured (human body) wears shoes that are not subjected to anti-static processing, and walks on a floor surface that is not subjected to anti-static processing. At this time, when the person to be measured touches the electrode of the electrostatic discharge measuring device, the failure generating force V of the person to be measured is obtained.₁Measure.
  Next, this person walks on the antistatic floor material 8 while wearing the antistatic shoes 9. At this time, when the person to be measured touches the electrode of the electrostatic discharge measuring device, the failure generating force V of the person to be measured is obtained.₂Measure.
  The countermeasure capability of the combination of the anti-static flooring 8 and the anti-static shoe 9 is the difference in the failure generating power V against the device to which the electrostatic countermeasure is applied.₁-V₂As required. Similarly, it is possible to measure the countermeasure ability by a combination of wearing antistatic socks, a wrist strap, and work clothes.
  Distributors such as antistatic flooring 8 and antistatic shoes 9Combination orDepending on the type of device, obtain countermeasures for antistatic materials and antistatic materials and place them in the catalog.
[0031]
  Note that the manufacturer of materials for countermeasures against static electricity and the manufacturer of materials for preventing static electricity may measure the countermeasure capacity of each material individually using an electrostatic discharge measuring device.
[0032]
(3) Countermeasures for static eliminator manufacturers
  The manufacturer of the static eliminator 12 measures the static eliminability of the static eliminator 12 using an electrostatic discharge measuring device to be described later. The method is as follows, for example.
  First, a test charged body having a constant size and material is charged to a test voltage (for example, 1000 V). When the electrostatic discharge measuring device is used, the electrode of the electrostatic discharge measuring device is selected according to the input impedance of the device to be subjected to static electricity countermeasures. Then, the test charging body is brought into contact with the electrode of the electrostatic discharge measuring device, and the failure generating force V of the test charging body is measured.₃Measure.
  Next, the static eliminator 12 is operated from a predetermined distance (for example, 30 cm) away from the test charged body. Then, the static eliminator 12 is turned off after a certain time (for example, 10 seconds).
  Next, the test charging body is brought into contact with the electrode of the electrostatic discharge measuring device, and the failure generating force V of the test charging body is measured.₄Measure. The static elimination capability of the static eliminator 12 is based on the difference V of the fault generation force with respect to the device to be subjected to static electricity countermeasures.₃-V₄As required. Similarly, the static elimination capability of the static eliminator 12 is determined according to the test charged body and device of different sizes and materials, and is placed in the catalog of the static eliminator manufacturer.
[0033]
(4) User response for on-site static electricity countermeasures
  Users are roughly classified into countermeasure managers (designers), enforcers (administrators), and on-site personnel.
  The person responsible for countermeasures (designer) determines that the failure generating power of an object that becomes a charged body at the site (for example, clean room 1) depends on the static electricity countermeasure ability of static electricity prevention materials and antistatic materials, and the static electricity removal ability of the static eliminator. Design to select antistatic material, antistatic material, and static eliminator so as to be smaller than the net static electricity resistance. There are an infinite number of combinations of materials and equipment that satisfy this condition, but the person in charge of countermeasures is required to reduce the failure generating power of the object by 1 [V] based on the static electricity countermeasure ability and the static elimination ability. Is calculated, cost effectiveness and cost life are evaluated, and an appropriate combination of materials and equipment is selected.
[0034]
  The enforcer (administrator) creates a work manual for the on-site staff and supervises the work of the on-site staff so that the on-site work can be performed as designed by the countermeasure manager (designer).
  The person in charge of the site appropriately arranges antistatic materials, antistatic materials, and static eliminators according to the work manual. For example, before disposing a static eliminator or the like, an electrostatic discharge measuring device to be described later is used to measure the fault generating force of an object that becomes a charged body existing in the field (clean room 1). In addition, after installing the static eliminator and the like, using a checker 41 to be described later, whether or not the failure generating force of the object on the site is smaller than the net electrostatic resistance of the device as designed, Check regularly.
[0035]
(5) On-site static electricity countermeasure procedures
  Assume that the user (responsible person for countermeasures) takes measures against static electricity, for example, for the device 3 with net static electricity resistance = 50 [V]. The user (field worker) first selects the electrode of the electrostatic discharge measuring device according to the input impedance of the device 3 and measures the failure generating power of the assembling device 4 and the worker 5 as charged bodies. As a result, for example, it is assumed that the measurement value of the fault generation force of the assembling apparatus 4 = 100 [V] and the measurement value of the fault generation force of the worker 5 (human body) = 200 [V].
[0036]
  The user (responsible person for countermeasures) should install the antistatic material, antistatic material, and static eliminator based on the catalog that describes the actual effects of the antistatic material and antistatic material, and the catalog of the static eliminator. investigate. At this time, the user (responsible person) calculates the cost required to reduce the failure generating power of the charged object by 1 [V] based on the static electricity countermeasure capability and the static elimination capability, and evaluates cost effectiveness. I do. Then, the user (the countermeasure manager) determines, for example, a combination of the antistatic floor material 8, the antistatic grounding shoes 9 and the work clothes 10 with the countermeasure capacity of the human body = 180 [V]. It is assumed that the static eliminator 12 of [V] is selected.
[0037]
  A user (on-site person in charge) lays a flooring 8 for static electricity countermeasures on the site (clean room 1), and attaches the static eliminating device 12. The worker 5 who performs the assembling work of the device 3 wears the selected work clothes 10 and wears anti-static shoes 9. Further, the wrist strap 11 may be worn.
  Then, the user (on-site person in charge) again selects the electrode of the electrostatic discharge measuring device according to the input impedance of the device 3, and measures the failure generating force of the assembling apparatus 4 and the worker 5 as a charged body.
  As a result, for example, it is assumed that the measured value of the fault generation force of the assembly apparatus 4 is 1 [V] and the measured value of the fault generation force of the worker 5 (human body) is 20 [V] as substantially designed. . Since all of these values are the net electrostatic resistance of the device = 50 [V] or less, it was possible to take a countermeasure against static electricity so that the device 3 did not cause an electrostatic failure.
[0038]
(6) Configuration and operation of electrostatic discharge measuring device
  Next, the configuration and operation of the electrostatic discharge measuring apparatus will be described in detail below.
  FIG. 2 shows an electrostatic discharge measuring device (hereinafter simply referred to as “electrostatic discharge measuring device”).Called "measurement equipment") 13 external view, FIG.Show circuit configurationFIG.
  FIG.As shown inThe measuring device 13 is exposed to the outside of the front surface of the box-shaped housing 22 and can change its direction, for example, twelve electrodes 23._k(K = 1 to 12), a display 24 exposed and fixed to the upper surface of the housing 22, and a circuit unit 25 housed in the housing 22.
[0039]
  Electrode 23_kThere are three types of diameters D, for example, D = 1 mm (k = 1 to 4), 5 mm (k = 5 to 8), and 10 mm (k = 9 to 12).
  The display 24 displays the value of the discharge voltage (failure generating force) received by the electrode 23 from the object to be charged.
  A power switch or the like (not shown) is attached to the outer surface of the housing 22.
[0040]
  The circuit unit 25 includes an electrode 23_kAnd the display 24, and as shown in FIG._k12 sets of discharge circuits 27 connected to each other_k(K = 1 to 12), a meter 28, a calculation unit 29, and an A / D conversion circuit 30 are provided.
  Discharge circuit 27_kRespectively, the resistor 31_k(Resistance value R_1k) And resistor 31_kVoltage divider circuit 32 connected to_k(Resistance value R_2k).
  Resistor 31_kIs electrode 23_kAnd a voltage dividing circuit 32_kIs connected to the ground electrode 33. Voltage divider circuit 32_kIs composed of a fixed resistor, for example.
[0041]
  Electrode 23_kTo discharge circuit 27_kTwelve paths that reach the grounding electrode 33 via the discharge path 34_k(K = 1 to 12) is formed. This discharge path 34_kThe impedance is determined by the capacitance D of the electrode and the resistance is the resistance R between ground RI.e.Electrode 23_kAnd the resistance between the ground electrode 33. There are four types of resistance R between grounds, for example, 1Ω, 100Ω, 1MΩ, and 100MΩ.
[0042]
  Discharge path 34_kSpecific combinations of the electrode diameter D and the resistance R between the ground are (D, R) = (1 mm, 1Ω), (1 mm, 100Ω), (1 mm, 1 MΩ), (1 mm, 100 MΩ), (5 mm, 1Ω) ), (5 mm, 100Ω), (5 mm, 1 MΩ), (5 mm, 100 MΩ), (10 mm, 1Ω), (10 mm, 100Ω), (10 mm, 1 MΩ), (10 mm, 100 MΩ), and k = 1. The case of ~ 12 is shown.
[0043]
  The meter 28 includes a discharge circuit 27._kResistor 31_kAnd voltage dividing circuit 32_kIs connected to the middle point by switches SW1 to SW12 so as to be switchable._kVoltage value V generated between_ak(K = 1 to 12) is measured. The calculation unit 29 calculates the measured value V of the meter 28._akTo electrode 23_kPotential V_bk(K = 1 to 12) is calculated. Potential V_bkIs represented by the following equation (1). The A / D conversion circuit 30 of the circuit unit 25 A / D converts the output signal of the calculation unit 29 and displays it on the display 24.Make.
[0044]
    V_bk= V_ak* (R_1k+ R_2k) / R_2k(1)
[0045]
  Next, the operation of the measuring device 13 will be described. Depending on the design value (the manufacturer's nominal value) of the input impedance of the device to be subjected to static electricity countermeasures, the electrode 23_k(Or discharge path 34_k) Is selected in advance. Then, the selected electrode is extended on the front surface of the measuring device 13, and the other eleven electrodes are bent toward the upper surface of the measuring device 13. Hereinafter, the selected electrode is represented as an electrode 23, and similarly, a discharge circuit 27, a voltage dividing circuit 32, a discharge path 34, a resistance value R₁, R₂, Voltage value V_a, V_bThe subscript k is abbreviated asNotationTo do.
[0046]
  When measuring the failure generating force received by the device from an object to be charged by the measuring device 13, first, a power switch (not shown) is turned on and then the electrode 23 is opposed to the object. 22 is brought close to the object, and the electrode 23 is brought into contact with the object. When the electrode 23 is brought into contact with the object, the object is discharged into the discharge path 34. That is, it is discharged to the ground electrode 33 through the electrode 23 and the discharge circuit 27, and the electrode 23 has a predetermined potential V with respect to the ground electrode 33._bOccurs.
[0047]
  When the electrode 23 is brought into contact with the object, the meter 28 generates a voltage V generated across the voltage dividing circuit 32._aAnd the calculation unit 29 converts the output signal of the meter 28 into the potential V generated at the electrode 23._bConvert to. Potential V_bIs a voltage V generated in the voltage dividing circuit 32._aAnd partial pressure resistance R₁, R₂Is represented by the above formula (1). The output signal of the calculation unit 29 is A / D converted by the A / D conversion circuit 30. Furthermore, the voltage value V_bIs displayed on the display 24 by the object V._bIs displayed. As a result, the failure generating power V_bIs measured.
[0048]
(7) Checker configuration and operation
  Next, the configuration and operation of the checker will be described in detail. FIG. 4 is an external view showing the external appearance of the checker 41, and FIG. 5 is a structural view showing the structure of the checker 41. In addition, the same reference number is attached | subjected to the structure same as the electrostatic discharge measuring apparatus 13. FIG.
  As shown in FIG. 4, the checker 41 includes an electrode 23 that is exposed and fixed to the front surface portion of the box-shaped housing 22 and a circuit portion 45 that is housed inside the housing 42. The circuit unit 45 is connected to the electrode 23 and includes a discharge circuit 27 to which the electrode 23 is connected, a comparison circuit 46, an amplifier 47, and a notification unit 48, as shown in FIG.
[0049]
  The discharge circuit 27 includes a resistor 31 (resistance value R₁) And a voltage dividing circuit 32 (resistance value R) connected to the resistor 31₂). The resistor 31 is connected to the electrode 23, and the voltage dividing circuit 32 is connected to the ground electrode 33.
[0050]
  The comparison circuit 46 is connected to the middle point of the resistor 31 and the voltage dividing circuit 32 of the discharging circuit 27, and a voltage value V generated between the voltage dividing circuits 32._aAnd a predetermined voltage value V_CCompare And the voltage value V_aIs the predetermined voltage value V_CAt the above time, a signal is output.
  The amplifier 47 is composed of, for example, a bipolar transistor, amplifies the output signal of the comparison circuit 46, and supplies the amplified signal to the notification unit 48.
  The notification unit 48 is composed of, for example, a piezo buzzer made of a piezoelectric ceramic, and emits a buzzer sound according to an input signal.
[0051]
  Next, the operation of the checker 41 will be described. When the checker 41 discriminates whether or not the failure generating force of the charged object causes electrostatic failure in the device, a predetermined voltage value V_CIs set in advance. Voltage value V_CIs determined by the nominal value of the manufacturer of the device to be subjected to static electricity countermeasures, and is set at the manufacturing stage of the checker 41 dedicated to the device.
[0052]
  First, after turning on a power switch (not shown), the casing 22 is brought close to the object in a state where the electrode 23 is opposed to the object to be a charged body, and the electrode 23 is brought into contact with the object. Alternatively, in the same manner as in an environment where the device is actually exposed to static electricity, the device is approached from the direction approaching the object on the production line or the like to the position where the device actually approaches.
[0053]
  When the electrode 23 is brought into contact with or close to the object, it is discharged from the object to the ground electrode 33 via the electrode 23 and the discharge circuit 27._bOccurs. In this case, the potential V generated at the electrode 23_bThe voltage V generated in the voltage dividing circuit 32 obtained by dividing the voltage V_aAnd a predetermined voltage value V_C Are compared by the comparison circuit 46..
[0054]
  The comparison circuit 46 has a voltage value V_aIs the predetermined voltage value V_CA signal is output at the above time. This output signal is amplified by the amplifier 47, and the notification unit 48 emits a buzzer sound. On the other hand, the voltage value V_aIs the predetermined voltage value V_CWhen it is smaller than this, the notification unit 48 does not emit a buzzer sound. Therefore, the buzzer can be sounded only when it is discriminated that an electrostatic failure due to the object occurs in the device.
[0055]
  According to the above-described embodiment, appropriate countermeasures are taken for a device to be subjected to static electricity countermeasures, so that the failure generation force of an object serving as a charged body is smaller than the net static electricity resistance of the device. Select materials for static electricity countermeasures, antistatic materials and static eliminatorsConstitutes a static electricity countermeasure system. This, The electrostatic failure of the device can be prevented.
[0056]
  In the above embodiment, the static electricity countermeasure for preventing static electricity failure of the device in the clean room has been described.The present inventionThe present invention is not limited to countermeasures against static electricity in electronic devices, and can be used, for example, as countermeasures against static electricity to prevent static electricity disasters in fibers, petroleum, chemicals, powders, copying machines, airplanes, and the like.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram for explaining a device assembly process in a clean room.
FIG. 2 is an external view of an electrostatic discharge measuring apparatus.
FIG. 3 is a configuration diagram of an electrostatic discharge measuring apparatus.
FIG. 4 is an external view of the checker.
FIG. 5 is a block diagram of the checker.
[Explanation of symbols]
  DESCRIPTION OF SYMBOLS 1 ... Clean room, 2 ... Work table, 3 ... Device, 4 ... Assembly apparatus, 5 ... Worker, 8 ... Floor material for static electricity measures, 9 ... For static electricity measures Shoes, 10 ... wrist strap, 11 ... work clothes, 12 ... static elimination device, 13 ... electrostatic discharge measuring device, 22 ... housing, 23 ... electrode, 24 ... display 25, 45 ... circuit unit, 27 ... discharge circuit, 28 ... meter, 29 ... calculation unit, 30 ... A / D conversion circuit, 31 ... resistor, 32 ... Voltage divider circuit, 33 ... Ground electrode, 34 ... Discharge path, 41 ... Checker, 46 ... Comparison circuit, 47 ... Amplifier, 48 ... Notification section.

Claims (2)

An electrostatic countermeasure system for preventing an electrostatic failure caused by discharge of a charged object to an apparatus, line or property (hereinafter referred to as “apparatus”) to be subjected to electrostatic countermeasures,
Arranged and Antistatic materials constituting a path for leakage to ground charges the object is charged, and the antistatic material having an antistatic function of the apparatus or the like, and a static eliminator for neutralizing the static electricity of the apparatus or the like Configured
A discharge voltage value received by the device or the like when the object is discharged to the device or the like is defined as a fault disaster occurrence force of the object ,
The discharge voltage that is actually input from the object to the device or the like when an electrostatic failure disaster occurs in the device or the like is defined as net static resistance of the device or the like ,
The difference between the disabled disaster force of objects located on the Antistatic materials and disability disaster power of the object located on the front of the Antistatic materials subjected to ESD protection, the Antistatic materials It is defined as the anti-static ability,
Define the difference between the anti-static material failure ability before antistatic processing and the anti-static material failure ability after antistatic processing as the anti-static material antistatic ability ,
When defining the difference between the disaster occurrence ability of the object to be neutralized and the failure occurrence ability of the object after the static elimination device neutralizes the static electricity of the object as the static elimination capability of the static elimination device ,
The antistatic material, the antistatic material, and the static eliminator are subjected to countermeasures based on the static electricity countermeasure capability of the antistatic material, the antistatic capability of the antistatic material, and the static elimination capability of the static eliminator. The electrostatic countermeasure system according to claim 1, wherein the object's ability to generate a disaster is selected to be smaller than the net static resistance of the device or the like . The Antistatic materials ESD protection capability, charge removal capability of the ESD protection capability, and the discharging device of the antistatic material is claimed in claim 1, characterized in that it is evaluated in the same physical quantity as impaired disaster force of the object Anti-static system.

Images