JP2009229373A - Evaluation implement for electron conductivity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evaluation implement capable of measuring correctly electron conductivity in a direction of cross section, especially for electron conductors of thin film. <P>SOLUTION: The evaluation implement includes two probes for measuring current and for measuring voltage in contact with the upper part of an electron conductor and two probes for measuring current and for measuring voltage in contact with the lower part of an electron conductor, where minimal distance between contact surfaces of the electron conductor with each current probe and voltage probe at the upper part and lower part, respectively, is less than 200% of thickness of electron conductor to be measured, and is characterized by measuring voltage between both voltage probes by passing current between both current probes. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY The present invention is an evaluation jig effective for evaluating electronic conductivity in an electron conductor, and in particular, various technologies including electric and chemical fields that require electric conductivity analysis in a cross-sectional direction of a thin film electronic conductor. Related to the field.

  A method for evaluating the electron conductivity of a conventional electron conductor will be described. As described in the non-patent document 1, for example, the electronic conductivity in the surface direction is 80 mm in length, 50 mm in thickness, and 20 mm in thickness as described in the resistivity test method by the 4-probe method for conductive plastics. The following four-terminal method (method (1)) is used in which four probes are brought into contact with each other at an interval of 5 mm from the upper part of the rectangular parallelepiped test piece and current is passed between the outer probes to measure the voltage between the inner probes. ing.

On the other hand, regarding the electron conductivity in the cross-sectional direction, for example, a two-terminal method in which a cylindrical probe is brought into contact with the upper and lower parts and the voltage between the upper and lower probes is measured while an electric current flows between the upper and lower probes ( The method (2)) is often used.
Japanese Industrial Standards, JIS K7194-1995: Resistivity testing method for conductive plastics using the 4-probe method

  However, when the electron conductivity in the cross-sectional direction is evaluated, the method (1) is a method for measuring the electron conductivity in the surface direction. Remained a problem that could not be accurately grasped. When evaluating the electron conductivity in the cross-sectional direction, in the method (2), the voltage drop due to the contact resistance of the portion where the upper and lower probes are in contact with the electron conductor is added to the measured voltage. In the case of evaluating a highly conductive material, there is a problem in that it is evaluated as an electron conductivity lower than the actual one.

  In addition, in an electrode formed by applying an electrode layer on a metal current collector used in, for example, a lithium ion battery, etc., a thin film electrode composed of a current collector layer and two layers in which an electrode layer is applied on the surface thereof In the evaluation of the electron conductivity in the cross-sectional direction, the evaluation of the electron conductivity (interface resistance) at the interface between the two layers is also important. The bulk electronic conductivity of each of the current collector layer and the electrode layer can be individually measured by the method (1) in which the surface direction is measured when there is no anisotropy. If the electron conductivity in the cross-sectional direction of the two layers by the current collector layer and the electrode layer can be accurately measured, the electronic conductivity at the interface between the two layers can be analyzed by analyzing each bulk electron conductivity from the electron conductivity. I think it can be evaluated. However, as described above, the conventional method has a problem that it is difficult to accurately measure the electronic conductivity in the cross-sectional direction of the thin film, and the analysis of the electron conductivity at the interface between the two layers is insufficient.

  As a result of conducting research while paying attention to the problems of the prior art as described above, the present inventor has found an evaluation jig capable of accurately measuring the electron conductivity in the cross-sectional direction of the thin-film electron conductor. Invented.

  The method according to claim 1 includes two measuring elements for current measurement and voltage measurement in contact with the upper part of the electron conductor, and two measurement elements for current measurement and voltage measurement in contact with the lower part of the electron conductor. A measuring element is provided, and the shortest distance in the contact surface between each current measuring element and the voltage measuring element at the upper and lower portions of the electronic conductor is 200% or less of the thickness of the electron conductor to be measured. An electronic conductivity evaluation jig characterized by passing a current between them and measuring a voltage between voltage measuring elements.

  According to a second aspect of the present invention, in the electronic conductivity evaluation jig, in the total of four current measuring elements and voltage measuring elements provided in the upper and lower parts, at least one of the upper current measuring element or the voltage measuring element. 2. The electron conductivity evaluation jig according to claim 1, wherein at least one of the lower current measuring element or the voltage measuring element includes an elastic mechanism.

  The shortest distance in the contact surface between each of the current measuring element and the voltage measuring element in contact with the upper and lower portions of the electron conductor is 200% or less of the thickness of the electron conductor to be measured. Accurately evaluate the electron conductivity in the cross-sectional direction of a thin-film electron conductor, which has been difficult in the past, by using an evaluation jig characterized by passing a current between them and measuring the voltage between voltage gauges can do. Furthermore, by providing these measuring elements with an elastic mechanism, it becomes possible to measure the electron conductivity in the cross-sectional direction more accurately by ensuring that all four measuring elements are in contact with each other.

  Further, the electron conductivity in the cross-sectional direction of the thin-film electron conductor is more accurately measured by the evaluation jig of the present invention, and the electronic conductivity at the interlayer interface is combined with the measurement value in the surface direction for the multi-layer test piece. Can also be analyzed.

  When evaluating the electron conductivity in the cross-sectional direction of the electron conductor, the evaluation jig of the present invention has two measuring elements for current measurement and voltage measurement that are in contact with the upper part of the electron conductor. An electron having two measuring elements for current measurement and voltage measurement in contact with the lower part and measuring the shortest distance on the contact surface between the current measuring element and the voltage measuring element at the upper and lower parts of the electron conductor. It is an electronic conductivity evaluation jig characterized in that it is 200% or less of the conductor thickness, and a current is passed between current measuring elements to measure a voltage between voltage measuring elements. The purpose of using two current measuring elements and voltage measuring elements for both the upper and lower parts of the electronic conductor is that when either the upper or lower part is a voltage current measuring element that serves both as a current measuring element and a voltage measuring element, The contact resistance between the probe and the surface of the electron conductor is always added to the voltage measurement value, and a value lower than the bulk electron conductivity of the electron conductor itself is measured and an accurate value cannot be obtained. In addition, the higher the electron conductivity of the sample to be measured, the greater the influence becomes.

  In the present invention, the shortest distance at the contact surface between the current measuring element and the voltage measuring element provided on the upper and lower parts of the electron conductor is 200% or less of the thickness of the electron conductor to be measured. This is because the shortest distance between the current measuring probe and the voltage measuring probe is important when measuring the voltage in the electric field generated by passing a current between the upper and lower current measuring probes. A large impact. This is because if this distance is long, the voltage in the electric field generated between the current measuring elements cannot be measured with high accuracy. In order to perform measurement with higher accuracy, it is preferable that this shortest distance is as small as the current measuring element and the voltage measuring element are electrically insulated, and 0% when the thickness of the electron conductor to be measured is 120% or less. It is more desirable to be larger. The insulation method between the current measuring probe and the voltage measuring probe generally involves applying an insulating surface treatment to one side surface. In many cases, the thickness is 1 μm or more. There is a possibility that it will be thin and nanometer level.

  Further, in the electronic conductivity evaluation jig, a total of four current measuring elements and voltage measuring elements provided in the upper and lower parts, at least one of the upper current measuring element or the voltage measuring element and at least the lower current measuring element. Alternatively, if one of the voltage measuring elements is provided with an elastic mechanism, all four measuring elements can be surely brought into contact with the measurement sample, and it is expected to accurately measure the electron conductivity in the cross-sectional direction. it can. This is because, when two probes from the upper and lower sides are brought into contact with each other, for example, when two upper or lower probe is fixed, the distance between the sample and the two tips when the two tips are brought into contact with the sample. This is because even if the difference is several μm, if the measurement sample is a hard material, only the closer probe contacts and cannot measure. That is, in order to bring the total of four measuring elements into contact with each other from the upper and lower sides, for example, a method in which the upper and lower current measuring elements are brought into contact with each other and the upper and lower voltage measuring elements provided with an elastic mechanism can be considered. In addition, by providing this elastic mechanism, it is possible to measure even the material with poor surface smoothness of the measurement sample when the four measuring elements come into contact with each other. As the elastic mechanism, for example, a structure in which a measuring element is fixed to an upper plate or a lower plate of a jig via an elastic body such as a spring or rubber is conceivable, but not particularly limited.

An embodiment of the present invention will be described below with reference to the drawings, taking an example of evaluation of electronic conductivity of a conductive sheet. FIG. 1 is a diagram showing an electron conductivity evaluation jig as an example of the present embodiment.
FIG. 1A is a perspective view showing the electron conductivity evaluation jig, and FIG. 1B is a cross-sectional view of the electron conductivity evaluation jig, and an electronic conductivity in which a power source and a voltage measuring device are connected. It is a figure explaining measurement of. The evaluation jig includes an upper plate 1, a bottom plate 2, an upper voltage measuring element 3, an upper current measuring element 5, a lower voltage measuring element 4, and a lower current measuring element 6. As shown in FIG. 1B, a voltage measuring element and a current measuring element are brought into contact with the conductive sheet sample 7 formed on the disk from above and below, and the positive electrode 9 of the power source 8 is minus to the upper current measuring element 5. By connecting the pole 10 to the lower current measuring element 6 and passing a current, and connecting the positive electrode 12 of the voltage measuring instrument 11 to the upper voltage measuring element 3 and the negative electrode 13 to the lower voltage measuring element 4 to measure the voltage. Electron conductivity can be evaluated. For example, the conductivity representing the electronic conductivity is calculated by substituting the resistance value obtained from the flowing current value, the measured current value and the measured voltage value into the following formula: The

Conductivity (S / cm) = sample thickness (cm) / (area through which current flows (cm ² ) / resistance value (Ω)

  The voltage measuring element and the current measuring element are not particularly limited as long as they are materials having electronic conductivity. In the case of the present embodiment, the current measuring element is shown in a ring shape, and the voltage measuring element is shown as a circular type arranged at the center of the inner diameter of the current measuring element. It is desirable that the shape of the tip contacting the sample of the current probe is a flat surface because it is easy to calculate the area through which current flows. In the case of this example, the shortest distance on the contact surface between the current measuring element and the voltage measuring element on the electron conductor is a half value of the value obtained by subtracting the outer diameter of the voltage terminal from the inner diameter of the voltage terminal. The value is desirably 200% or less of the electron conductor sample thickness. For example, when the sample thickness is 100 μm, the shortest distance is preferably 200 μm or less, more preferably 120% or less and 120 μm or less. This is because the voltage in the electric field generated between the current terminals is captured as close as possible from the outside of the current terminals. The shorter the shortest distance between the current probe and the voltage probe, the higher the possibility that the two probes will come into electrical contact. Therefore, the side surfaces of the current probe or voltage probe facing each other should be insulated. It is desirable to give it. Further, the distance between the tip of the current measuring probe and the voltage measuring probe and the surface of the sample must be the same. This is because, as shown in FIG. 1 (b), when a sample is sandwiched between four measuring elements from the upper part and the lower part with this evaluation jig, if there is even one measuring element that is not in contact, accurate measurement cannot be performed. Because.

  Next, an evaluation jig capable of measuring a more reliable value in the electronic conductivity evaluation of the electron conductor will be described. FIG. 2 shows an electronic conductivity evaluation jig as an example of the present embodiment according to the present invention. FIG. 2 (a) is a perspective view showing the electron conductivity evaluation jig, and FIG. 2 (b) is a cross-sectional view of the electron conductivity evaluation jig connected to a power source and a voltage measuring device. It is a figure explaining measurement of. The evaluation jig includes an upper plate 1, a bottom plate 2, an upper voltage measuring element 3 having a spring elastic mechanism, an upper current measuring element 5, a lower voltage measuring element 4 having a spring elastic mechanism, and a lower current measuring element 6. The As shown in FIG. 2 (b), the upper and lower current measuring elements are pressed by the top and bottom plates to come into contact with the conductive sheet sample 7, and the voltage measuring elements provided with an elastic mechanism by a spring at the center side of the current measuring elements from above and below. Independent of the probe, the conductive sheet sample 7 is contacted. A voltage measuring element and a current measuring element are brought into contact with the conductive sheet sample 7 formed on the disk from above and below, and the positive electrode 9 of the power source 8 is connected to the upper current measuring element 5 and the negative electrode 10 is connected to the lower current measuring element 6. The electrical conductivity can be evaluated by connecting and passing a current, and measuring the voltage by connecting the positive electrode 12 of the voltage measuring instrument 11 to the upper voltage measuring element 3 and the negative electrode 13 to the lower voltage measuring element 4. By providing this elastic mechanism, even when the measurement sample is hard, the thickness is uneven, or the surface smoothness is poor, it is possible to measure by ensuring that the four probe points come into contact with each other, and the data is always highly reliable. In particular, it is considered to be a very effective means for evaluating the electronic conductivity of a thin film.

  Hereinafter, examples of the present invention will be described in more detail.

(1) Graphitized mesocarbon microbeads MCMB 93 parts by weight, conductive material acetylene black 2 parts by weight, binder polyvinylidene fluoride (PVDF) 5 parts by weight are mixed with diluent N-methylpyrrolidone (NMP). A material slurry was obtained. The slurry was applied to one side of a 40 μm thick polyester film serving as a base material, dried, and then pressed to prepare a negative electrode layer for a lithium ion battery having a thickness of 90 μm. Next, the negative electrode layer was peeled from the polyester film substrate, punched into a disk shape having a diameter of 11 mm, and used as a conductive sheet sample for evaluating electronic conductivity. This sample is of a type having no great anisotropy in the cross-sectional direction and the surface direction.

(2) The electronic conductivity evaluation of the conductive sheet sample is shown in FIG. The evaluation jig includes an upper plate 1 and a bottom plate 2 of insulating plastic, an elastic mechanism using a spring, and an upper voltage measuring element 3 and a lower voltage measuring element 4 each having a circular flat shape having a diameter of 0.6 mm and a circular shape having a diameter of 11 mm. It is composed of an upper current measuring element 5 and a lower current measuring element 6 which have a ring shape with a 0.8 mm diameter removed from the center side and a flat surface. In both the upper and lower parts, a voltage measuring element is arranged at the center of the current measuring terminal, and the distance between the current measuring element and the voltage measuring element is 0.1 mm. Therefore, the shortest distance at the contact surface between the current measuring element and the voltage measuring element with the electron conductor is 111% of the 90 μm thickness of the electron conductor to be measured.

(3) As shown in FIG. 2 (b), a current measuring element and a voltage terminal are brought into contact with the conductive sheet sample 7 from above and below, and the positive electrode 9 of the power source 8 is connected to the upper electric current measuring element 5. Connect to the lower current measuring element 6 to pass a current of 100 mA, connect the positive electrode 12 of the voltage measuring device 11 to the upper voltage measuring element 3 and connect the negative electrode 13 to the lower voltage measuring element 4 to measure the voltage and measure the electron conductivity. The calculated value was 4 × 10 ⁰ (S / cm). On the other hand, from the upper part of the conductive sheet sample 15 obtained by cutting the conductive sheet into a strip having a width of 10 mm and a length of 20 mm using a jig for evaluating the electron conductivity in the general surface direction shown in FIG. Voltage measuring elements 17 and 18 having a circular flat shape with a diameter of 3 mm and current measuring elements 16 and 19 having a circular flat shape with a diameter of 3 mm are brought into contact with each other at 5 mm intervals, and a current of 1 mA is applied between the current measuring elements. It was 5 × 10 ⁰ (S / cm) when the electric conductivity was calculated by measuring the voltage between the voltage measuring elements. Therefore, the electron conductivity in the cross-sectional direction and the electron conductivity in the surface direction measured with this evaluation jig showed the same value.
(Comparative Example 1)

  Hereinafter, a comparative example in which only the evaluation jig is different from the conductive sheet sample will be described.

With the evaluation jig shown in FIG. 2, a design jig in which only the dimension of the current probe was changed with respect to Example 1 was produced.
The evaluation jig includes an upper plate 1 and a bottom plate 2 of an insulating plastic, an upper voltage measuring element 3 and a lower voltage measuring element 4 having a circular flat shape with a tip diameter of 0.6 mm and having an elastic mechanism by a spring, and a center of a circle having a diameter of 11 mm. It is composed of an upper current measuring element 5 and a lower current measuring element 6 having a ring shape with a diameter of 1.4 mm removed from the side and a flat surface. In both the upper and lower portions, a voltage measuring element is arranged at the center of the current measuring terminal, and the distance between the current measuring element and the voltage measuring element is 0.4 mm. Therefore, the shortest distance at the contact surface between the current measuring element and the voltage measuring element with the electron conductor is 444% of the 90 μm thickness of the electron conductor to be measured. Similarly to Example 1, the current probe and the voltage terminal were brought into contact from above and below, a current of 100 mA was passed, the voltage between the voltage probes was measured, and the electron conductivity was calculated to be 2 × 10 ² (S / cm). Even if the electric field does not generate strongly to the voltage terminal, the conductive sheet sample has more than one digit with respect to the electron conductivity in the surface direction shown in Example 1 although there is no anisotropy in the surface direction and the cross-sectional direction. High values were calculated, and the measured values gave suspicious results. This result is because the shortest distance at the contact surface between the current measuring element and the voltage measuring element with the electron conductor exceeds 444% and 200%.
(Comparative Example 2)

  Hereinafter, another comparative example in which only the evaluation jig is different as in Comparative Example 1 using the same sample as the conductive sheet sample will be described.

With the evaluation jig shown in FIG. 3, the electronic conductivity was evaluated using the same sample as the conductive sheet sample. In the measurement using the evaluation jig, from the upper and lower portions of the sample, a current-voltage measuring element 14 having a cylindrical shape with a diameter of 11 mm and a flat tip is brought into contact, a current of 100 mA is passed, and the voltage between the current-voltage measuring elements is measured to measure the voltage. When the conductivity was calculated, it was 4 × 10 ⁻¹ (S / cm), which was one order of magnitude lower than the electron conductivity in the surface direction shown in Example 1. The reason for this low electron conductivity is that the voltage drop due to the contact resistance of the parts where the upper and lower current / voltage gauges are in contact with the electron conductor is added to the measured voltage, resulting in a lower electron conductivity. It was thought that this was because

  As described above, Comparative Example 1 (when the shortest distance on the contact surface between the current measuring element and the voltage measuring element with the electron conductor exceeds 200%) and Comparative Example 2 (two for current measurement and voltage measurement) In the case where the measuring element is not provided), the values of the electroconductivity of the electrically conductive sheet sample having no anisotropy greatly differed between the surface direction and the cross-sectional direction. Then, the same value was obtained in both directions, and the effectiveness of the evaluation jig according to the present invention was confirmed.

  By using the evaluation jig of the present invention, it becomes possible to more accurately measure the electron conductivity in the cross-sectional direction, particularly in the thin-film electron conductor, and the electrical and chemical fields that require characteristic analysis in the cross-sectional direction of the thin film It is a very effective means in various technical fields including

It is a figure which shows the electronic conductivity evaluation jig | tool which is an example of this embodiment. (A) It is a perspective view which shows the evaluation jig | tool of electronic conductivity. (B) It is sectional drawing of an electronic conductivity evaluation jig | tool, and a figure explaining the measurement of electronic conductivity. It is a figure which shows the electronic conductivity evaluation jig | tool which is an example of this embodiment. (A) It is a perspective view which shows the evaluation jig | tool of electronic conductivity. (B) It is sectional drawing of an electronic conductivity evaluation jig | tool, and a figure explaining the measurement of electronic conductivity. It is a figure which shows the electronic-conductivity evaluation jig | tool which is a comparative example. It is a figure which shows the electronic conductivity evaluation jig | tool in the general surface direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Top plate 2 Bottom plate 3 Upper voltage measuring element 4 Lower voltage measuring element 5 Upper current measuring element 6 Lower current measuring element 7 Conductive sheet sample (electronic conductor)
8 Power supply 9 Positive pole of power supply 10 Negative pole of power supply 11 Voltage measuring instrument 12 Positive pole of voltage measuring instrument 13 Negative pole of voltage measuring instrument 14 Current voltage measuring element 15 Conductive sheet sample (electronic conductor)
16 Current Measuring Element 17 Voltage Measuring Element 18 Voltage Measuring Element 19 Current Measuring Element

Claims (2)

It has two gauges for current measurement and voltage measurement in contact with the upper part of the electron conductor, and two gauges for current measurement and voltage measurement in contact with the lower part of the electron conductor. In FIG. 5, the shortest distance of the contact surface between each current measuring element and the voltage measuring element on the electron conductor is 200% or less of the thickness of the electron conductor to be measured. An electron conductivity evaluation jig characterized by measuring a voltage between the two. In the electronic conductivity evaluation jig, in the total of four current measuring elements and voltage measuring elements provided in the upper and lower parts, at least one of the upper current measuring element or voltage measuring element and at least the lower current measuring element or voltage. The electronic conductivity evaluation jig according to claim 1, wherein one of the measuring elements includes an elastic mechanism.

Images