CN217766197U - Sample composition for testing resistivity of heterogeneous material - Google Patents

Abstract

An object of the utility model is to provide a sample composition for testing heterogeneous material resistivity, the sample combination comprises heterogeneous material sample, pure copper sample and the supplementary piece sample of pure copper, wherein: the heterogeneous material sample consists of a heterogeneous material body and two pure copper blocks, wherein the pure copper blocks are respectively positioned at the upper end and the lower end of the heterogeneous material body and are bonded on the heterogeneous material body through conductive silver paste, and the section sizes of the pure copper blocks and the heterogeneous material body are the same; the pure copper auxiliary block sample consists of two pure copper blocks, and the two pure copper blocks are bonded together through conductive silver paste. The sample composition can solve the problem of large error caused by non-uniformity of the sample when the voltage of the sample is tested by four contacts.

Description

A sample composition for testing the resistivity of heterogeneous materials

technical field

The utility model belongs to the field of material electrical performance testing, and particularly provides a sample composition for testing the resistivity of heterogeneous composite materials by a four-contact method.

Background technique

The four-contact method is a better test scheme to eliminate the error introduced by the lead resistance (or reduce it to a smaller value). Generally used to measure the resistance of lower resistance, the principle of the four-contact method for more accurate measurement is: the current and voltage of the sample are measured through the current loop and the voltage loop respectively, eliminating the impedance of the contact resistance of the lead wire and the probe, thereby Get a more accurate resistor value (see Figure 1).

When the four-contact method tests homogeneous materials, there is no difference in the position of the voltage electrode on the sample. However, when testing layered composite materials or heterogeneous samples, the voltage values measured by the voltage electrode at different sampling positions are quite different, resulting in large error in the results.

Utility model content

The purpose of the utility model is to provide a sample composition for testing the resistivity of heterogeneous materials, which mainly solves the problem of large errors caused by uneven samples when testing the sample voltage with four contacts.

Technical scheme of the present invention is as follows:

A sample composition for testing the resistivity of heterogeneous materials, characterized in that: the sample combination is composed of heterogeneous material samples, pure copper samples and pure copper auxiliary block samples, wherein:

The heterogeneous material sample is composed of a heterogeneous material body and two pure copper blocks, wherein the pure copper blocks are respectively located at the upper and lower ends of the heterogeneous material body, and are bonded to the heterogeneous material body by silver paste, The pure copper block has the same cross-sectional size as the heterogeneous material body;

The pure copper auxiliary block sample is composed of two pure copper blocks bonded together by silver paste.

further:

The cross-sectional dimensions of the pure copper blocks are the same.

The pure copper block is made of oxygen-free copper.

The end face of the pure copper block is perpendicular to the axis, and the parallelism of the upper and lower end faces is less than 20 μm.

The end face of the heterogeneous material body is perpendicular to the axis, and the parallelism of the upper and lower end faces is less than 20 μm.

The silver paste is a conductive silver paste with a silver content ≥ 90%.

The specific steps for testing the resistivity of heterogeneous materials using the sample composition described in the utility model are as follows:

Step 1. Prepare the heterogeneous material body, and measure the length, width and height of the heterogeneous material body (for calculating its resistivity).

Step 2, preparing a pure copper sample, and testing the resistivity of the pure copper sample (for calculating the resistance of the pure copper block).

Step 3: Prepare multiple groups of pure copper blocks, the cross-sectional size of which is consistent with the cross-sectional size of the heterogeneous material body. Two pure copper blocks are bonded together by conductive silver paste to prepare a pure copper auxiliary block sample, and then the overall resistance is tested, compared with the resistance of the pure copper sample, and the resistance of the two pure copper blocks is subtracted to obtain the contact resistance. Take the average value of multiple measurements to obtain the average contact resistance.

Step 4. Bond the heterogeneous material body and the pure copper block together through conductive silver paste to form a combination with a heterogeneous material in the middle and pure copper blocks at both ends, and test the overall resistance of the combination (as shown in Figure 3 As shown in the figure, the heterogeneous material body is made of composite material).

Step 5: Measure the effective length of the pure copper block that actually participates in the resistance measurement, and calculate the effective resistance of the pure copper block that participates in the measurement. The total resistance minus the effective resistance and the average contact resistance of the pure copper block. Get the resistance of the inhomogeneous material. Based on the dimensions of the bulk of the heterogeneous material, its resistivity is calculated.

Step six, testing the resistivity of the heterogeneous material in different directions.

The utility model adopts adding pure copper conductive block at both ends of the heterogeneous material, and bonding the pure copper conductive block and the heterogeneous material through silver paste to form a combination. The test electrode test includes part of the pure copper conductive block, contact resistance , Inhomogeneous material resistance. Resistance includes pure copper conductive block resistance, heterogeneous material resistance and contact resistance. The exact value of contact resistance is difficult to determine, but there is a certain range. When the contact resistance is much smaller than the resistance of the heterogeneous material, the average contact resistance of multiple measurements can be used as the contact resistance. The resistance of the composite can be obtained after deducting the pure copper conductive block and the average contact resistance. According to the resistance The resistivity of heterogeneous materials can be obtained from the rate formula.

Description of drawings

Figure 1 Schematic diagram of the principle of resistivity measurement by four-contact method.

Fig. 2 Schematic diagram of the sample structure used in the measurement of resistivity by the four-contact method.

Fig. 3 Schematic diagram of the principle of calculating the resistivity of the composite composed of heterogeneous materials and pure copper.

Fig. 4 Schematic diagram of the structure of a heterogeneous material sample in which the current is parallel to the direction of the graphite sheet (the direction of the arrow is the direction of the current).

Fig. 5 Schematic diagram of the structure of a heterogeneous material sample in which the current is perpendicular to the direction of the graphite sheet (the direction of the arrow is the direction of the current).

Fig. 6 Schematic diagram of the structure of the pure copper sample and the pure copper auxiliary block sample.

Reference signs: 1. Inhomogeneous material sample, 2. Pure copper sample, 3. Pure copper auxiliary block sample, 4. Pure copper block, 5. The first contact electrode of the constant current circuit, 6. The second constant current circuit Contact electrode, 7, the first contact electrode of the voltage loop, 8, the second contact electrode of the voltage loop, 9, the conduction resistance, 10, the resistance to be measured.

Detailed ways

The solution of the present invention will be described in detail below in conjunction with the accompanying drawings. The following examples are carried out on the premise of the technical solution of the present invention, and specific implementation schemes and operation processes are provided, but the protection scope of the present invention is not limited to the following examples.

A sample composition for testing the resistivity of heterogeneous materials, said sample combination is made up of heterogeneous material sample 1, pure copper sample 2 and pure copper auxiliary block sample 3, wherein:

The heterogeneous material sample 1 is composed of a heterogeneous material body and two pure copper blocks 4, wherein the pure copper blocks 4 are respectively located at the upper and lower ends of the heterogeneous material body, and are passed through a conductive silver paste (silver content ≥ 90 %) bonded on the heterogeneous material body, the pure copper block 4 has the same cross-sectional size as the heterogeneous material body;

The pure copper auxiliary block sample 3 is composed of two pure copper blocks 4, and the two pure copper blocks 4 are bonded together by conductive silver paste.

The pure copper sample 2 and the pure copper block 4 are made of oxygen-free copper, and their cross-sectional dimensions are the same.

The end face of the pure copper block 4 is perpendicular to the axis, and the parallelism of the upper and lower end faces is less than 20 μm.

The end face of the heterogeneous material body is perpendicular to the axis, and the parallelism of the upper and lower end faces is less than 20 μm.

Test method for resistivity of heterogeneous materials:

step one:

Prepare the heterogeneous material body (the heterogeneous material is layered pyrolytic graphite), a cube with a size of 4*4*4mm, the roughness of each surface is 3.2μm, and the parallelism of 3 pairs of parallel surfaces is not greater than 20μm. The three faces of the top corner are perpendicular to each other.

Step 2: Prepare a pure copper sample with a size of 4*4*15mm, and test the resistivity of pure copper, and the measured resistivity of pure copper is 17.7nΩm.

Step 3: Prepare four pure copper blocks with a size of 4*4*6mm. Two pieces of pure copper are bonded together with conductive silver paste. After curing, the resistance is measured three times and the average value is 88nΩ, and the contact resistance is obtained by subtracting the corresponding pure copper resistance of 8.5nΩ. Repeated three times to obtain an average contact resistance of 79.5nΩ.

Step 4: The resistivity of the layered pyrolytic graphite has directionality, and there is a large difference between the current perpendicular to the graphite sheet and the current parallel to the graphite sheet. First test the resistivity of the sample parallel to the current direction. Two pure copper blocks and the layered pyrolytic graphite body are bonded together through silver paste to form a combination with a size of 4*4*16mm. Keeping the current parallel to the direction of the layered pyrolytic graphite, the overall resistance of the combination was tested to be 579.2nΩ.

Step 5. Know that the distance between the two electrodes is 7.8mm, the height of the heterogeneous material body is 4mm, and the effective length of the pure copper block actually participating in the resistance measurement is 7.8-4.0=3.8mm, calculate the effective resistance of the pure copper block participating in the measurement The value is 4.4nΩ. The total resistance minus the effective resistance and the average contact resistance of the pure copper block: 579.2-4.4-79.5*2=415.8nΩ. The electrical resistance of the layered pyrolytic graphite bulk is obtained. According to the size of the layered pyrolytic graphite body, its resistivity is calculated to be 0.853nΩm.

Step 6. Repeat steps 1 to 5 to obtain a total resistance of 288μΩ, subtract the contact resistance and the resistance of the pure copper block: 288μΩ-4.4nΩ-79.5*2nΩ=287.8μΩ, and calculate the layered pyrolytic graphite in the layered direction perpendicular to the current direction The resistivity is 0.593μΩm.

The above-mentioned embodiments are only to illustrate the technical concept and characteristics of the present utility model, and its purpose is to enable those familiar with this technology to understand the content of the present utility model and implement it accordingly, and not to limit the protection scope of the present utility model. All equivalent changes or modifications made according to the spirit of the utility model shall fall within the protection scope of the utility model.

In addition, descriptions of known structures and technologies are omitted herein to avoid unnecessarily confusing the concept of the present invention.

Claims (6)

1. A sample composition for testing the resistivity of heterogeneous material, is characterized in that: described sample combination is made up of heterogeneous material sample, pure copper sample and pure copper auxiliary block sample, wherein: The heterogeneous material sample is composed of a heterogeneous material body and two pure copper blocks, wherein the pure copper blocks are respectively located at the upper and lower ends of the heterogeneous material body, and are bonded to the heterogeneous material body by silver paste, The pure copper block has the same cross-sectional size as the heterogeneous material body; The pure copper auxiliary block sample is composed of two pure copper blocks bonded together by silver paste. 2. The sample composition for testing the resistivity of heterogeneous materials according to claim 1, characterized in that: the cross-sectional dimensions of the pure copper blocks are the same. 3. The sample composition for testing the resistivity of heterogeneous materials according to claim 1, characterized in that: the pure copper block is made of oxygen-free copper. 4. The sample composition for testing the resistivity of heterogeneous materials according to claim 1, characterized in that: the end face of the pure copper block is perpendicular to the axis, and the parallelism between the upper and lower end faces is less than 20 μm. 5. The sample composition for testing the resistivity of heterogeneous materials according to claim 1, characterized in that: the end face of the heterogeneous material body is perpendicular to the axis, and the parallelism of the upper and lower end faces is less than 20 μm. 6. The sample composition for testing the resistivity of heterogeneous materials according to claim 1, wherein the silver paste is a conductive silver paste with a silver content ≥ 90%.

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