KR101955520B1 - Method of determining whether a dielectric material is defective - Google Patents

Abstract

A method for determining whether or not a dielectric material is defective according to an embodiment of the present disclosure includes the steps of determining a defective state of the dielectric material by measuring a voltage across both ends of the dielectric material with a temperature difference between both ends of the dielectric material .

Description

A method of determining whether a dielectric material is defective or not,

The present disclosure relates to a method of determining whether a dielectric material is defective, and more particularly, to a method of determining whether a multilayer ceramic capacitor (MLCC) material is defective by using a Seebeck effect.

Among the dielectric materials, MLCC is a typical passive component and is used for stabilization circuit of DC power supply and filter circuit of high frequency signal. The larger the capacity of the MLCC, the greater the electric energy that can be stored, so there is a great demand for high capacity MLCC. In order to increase the capacity without increasing the volume, there is no way but to increase the voltage applied to the unit thickness by decreasing the thickness of the dielectric layer. However, as the thickness becomes thinner, the probability of failure due to breakdown increases in terms of reliability although it may be advantageous in terms of the capacitor capacity of the product.

Before selling MLCC products, the permittivity can be inspected and sold in full, but reliability is difficult to score. The reason for this is that if the reliability is weakly tested, many defective products are sold, and if the inspection is conducted under severe conditions in order to accurately check the reliability, the product is likely to fail during the inspection. There are four typical examples of the existing defective MLCC inspection methods.

1) Measurement of hole count

This is a method of measuring the electrical conductivity directly at room temperature and measuring the charge concentration. The number of charges (concentration) is directly measured to estimate the possibility of failure by reduction. The advantage of this method is that it directly measures the number of electrons generated. However, there is a problem that measurement can be performed only when the electric conductivity is as high as the semiconductor level. In addition, there is also a problem that an error due to the measurement of the hole coefficient is large in the case of an MLCC including a dielectric material close to an insulator.

2) Measurement of breakdown voltage (BDV)

This is a method of measuring the voltage at which a failure occurs in an insulator. In this method, a high voltage at a room temperature is applied to suddenly lower the resistance (the inverse of the conductivity) to be. The advantage of this method is that it can accurately measure the fault voltage of the MLCC. However, there is a disadvantage in that it is impossible to cause BDV measurement specimens to fail due to the application of a very large voltage.

3) Insulation resistivity (IR) measurement

This is a method of measuring the resistance of a non-conductor, which is a method of measuring the resistance (inverse of conductivity) by applying a high voltage at room temperature and calculating the concentration of charge to estimate the possibility of failure by reduction. The advantage of this method is that it can measure the resistance of the non-conductor (the inverse of the conductivity). However, since it is evaluated by the log scale value, it is impossible to accurately discriminate due to large error, and furthermore, the failure of the product mainly occurs at a high temperature (cell phone is easily raised by 70 to 80 degrees) There is a problem.

4) High-temperature IR measurement

This is a method for measuring the resistance of an insulator, which is a method of measuring the resistance (inverse of conductivity) by applying a high voltage at a high temperature and calculating the concentration of charge to estimate the possibility of failure by reduction. This method has the advantage of evaluating the IR of the high temperature to identify the defective product with the highest precision. However, there is a problem that application of a high voltage at a high temperature may cause failure of the MLCC.

Therefore, it is necessary to introduce a new method to the inspection method of finished product MLCC.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to discriminate whether a dielectric material, particularly an MLCC material, is defective by applying a temperature difference without applying a voltage.

According to an aspect of the present invention, there is provided a method of determining whether a dielectric material is defective or not by measuring a voltage across both ends of the dielectric material with a temperature difference between both ends of the dielectric material, A method for determining whether or not a dielectric material is defective is disclosed.

In one embodiment, the step of determining whether the dielectric material is defective includes the steps of applying heat to one end of the dielectric material, measuring a voltage across both ends of the dielectric material, and determining whether the voltage is less than or equal to a predetermined value It may be determined that the dielectric material is defective.

In one embodiment, the dielectric material may be a multilayer ceramic capacitor (MLCC) material.

In one embodiment, the MLCC may comprise a BaTiO ₃ dielectric.

In another aspect of the present disclosure, there is provided a method of determining whether or not a dielectric material is defective, comprising: determining a defect of the dielectric material by measuring a Seebeck coefficient of the dielectric material; / RTI >

In one embodiment, the step of determining whether or not the dielectric material is defective includes the steps of applying heat to one end of the dielectric material, calculating a temperature difference and a voltage at both ends of the dielectric material, And determining that the dielectric material is defective if the debonding coefficient is less than or equal to a predetermined value.

As a method for discriminating whether or not a dielectric material of the present disclosure, particularly a multilayer ceramic capacitor (MLCC), is defective, it is not a method of applying a voltage to an MLCC but a method of generating a voltage when a temperature is applied. Which is an advantage compared with the conventional " BDV measurement " method). In addition, since it is only required to provide a temperature difference, it is not necessary to raise the temperature to a high temperature, so that the product does not cause a malfunction (a merit in contrast to the conventional "high-temperature IR measurement" method). In addition, the method of the present disclosure is suitable for measuring the concentration of a dielectric (nonconductor) having a low conductivity (an advantage compared with the conventional method of " measuring the hole count "). In addition, the Seebeck coefficient is not a measure of the electron concentration, but it can measure the difference of concentration at both ends, so that the analysis can be done precisely (compared with the conventional "IR measurement" method).

1 shows an embodiment of an MLCC;
2 is a graph showing changes in the Seebeck coefficient and the conductivity according to the change of the charge density.
3 (a) and 3 (b) are diagrams showing the degree of voltage generation when a temperature difference is given to both ends of an MLCC material according to an embodiment of the present disclosure;
FIG. 4 is a flowchart illustrating a process of determining whether a MLCC material is defective according to an embodiment of the present disclosure; FIG.
5 is a flowchart illustrating a process for determining whether a MLCC material is defective according to another embodiment of the present disclosure.

Brief Description of the Drawings The advantages and features of the present disclosure and how to accomplish them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. It should be understood, however, that the present disclosure is not limited to the embodiments disclosed herein but may be embodied in many different forms and should not be construed as limited to the specific embodiments set forth herein, To fully explain the scope of the invention to a person skilled in the art, and this disclosure is only defined by the scope of the claims.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. For example, an element expressed in singular < Desc / Clms Page number 5 > terms should be understood to include a plurality of elements unless the context clearly dictates a singular value. Also, in this disclosure, it is to be understood that the terms " comprises, " or " having ", and the like, specify only those features, integers, steps, operations, elements, The use of the term does not exclude the presence or addition of one or more other features, numbers, steps, operations, elements, parts or combinations thereof. Further, in the embodiments described herein, 'module' or 'sub-unit' may mean at least one function or a functional part performing an operation.

In addition, all terms used herein, including technical or scientific terms, unless otherwise defined, have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and may be interpreted in an ideal or overly formal sense unless explicitly defined in the specification of the present disclosure It does not.

The preferred embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. However, in the following description, when there is a possibility that the gist of the present disclosure may be unnecessarily blurred, a detailed description of widely known functions and configurations will be omitted.

1 is a diagram illustrating an embodiment of an MLCC.

The MLCC 100 includes a plurality of internal electrodes 110 and a dielectric 120, and the dielectric may include, for example, BaTiO ₃ . Capacitances C ₁ , C _2, C _3, C _{4, and} C ₅ are generated between the plurality of internal electrodes 100. C _total = C ₁ + C ₂ + C ₃ + C ₄ (C ₁ , C _2, C _3, C _{4 and} C ₅ ) are generated between the six internal electrodes 110 in FIG. + C ₅ .

The MLCC 100 may include, for example, 1) powder milling, 2) foil casting, 3) inner electrode printing, 4) stacking, 5) lamination (6) cutting, (7) binder burn out, (8) sintering, (9) tumbling, (10) terminal dipping, (11) termination plating In order to prevent the oxidation of the NI electrode, the heat treatment process (sintering) can not be heat-treated in air, but all of the hydrogen (Reducing) atmosphere Heat treatment should be done.

At this time, electrons (see "e" in FIG. 3) are generated as a large amount of Ba ions and Ti ions are reduced in the BaTiO 3 dielectric layer, which causes poor reliability. In particular, the thinner the BaTiO3 dielectric layer becomes, the more vulnerable it becomes.

2 is a graph showing the change in the Seebeck coefficient and the conductivity according to the change of the charge density.

In FIG. 2, as the carrier concentration of the x-axis, that is, the charge concentration changes from a semiconductor to a heavily doped semiconductor to a metal, the Seebeck coefficient gradually decreases However, it can be seen that the electric conductivity gradually increases. In other words, in FIG. 2, the "red color Seebeck coefficient" has a larger value as the charge concentration on the x axis is lower, unlike the "blue electrical conductivity". Therefore, it is more accurate to measure the Seebeck coefficient than to measure the electric conductivity (resistance) in the dielectric near the non-conductor.

3 (a) and 3 (b) are views showing the degree of voltage generation when a temperature difference is given to both ends of an MLCC material according to an embodiment of the present disclosure.

3 (a), it can be seen that when a temperature difference is given to both ends of the MLCC 100 by heating one end of the material of the MLCC 100 by the heating means 310, a high (+) voltage is generated . 3 (b), when a temperature difference is given to both ends of the material of the MLCC 100 by heating one end of the MLCC 100 by the heating means 310, a relatively low (+) voltage is generated . The heating means 310 can be, for example, an electric heating line, an infrared ray, or a gas jet, but is not limited thereto.

The material of the MLCC 100 in FIG. 3 (a) is a case of having a large bending strength, and since the charge density is low due to no degradation, it can be determined that the material is good. However, the material of the MLCC 100 in FIG. 3 (b) has a small bake-crack coefficient. Since the deterioration occurs and the charge density is high, it can be determined to be a defective product.

FIG. 4 is a flowchart illustrating a process of determining whether the MLCC material is defective according to an embodiment of the present disclosure, and FIG. 5 is a flowchart illustrating a process of determining whether a MLCC material is defective according to another embodiment of the present disclosure.

Referring to FIG. 4, a method of determining whether the material of the MLCC 100 is defective includes a step S 401 of applying heat to one end of the MLCC 100. Thereafter, the voltage across both ends of the MLCC 100 is measured (S402). If the voltage is below the predetermined value, it is determined that the material of the MLCC 100 is defective (S404). The predetermined voltage value can be appropriately determined according to the type of the MLCC 100. For example, 600 [mu] V, 400 [mu] V, 200 [mu] V, and the like.

Referring to FIG. 5, a method of determining whether a material of the MLCC 100 is defective includes the step of applying heat to one end of the MLCC 100 (S501). Thereafter, the temperature difference and the voltage applied to both ends of the MLCC material 100 are measured to calculate the Seebeck coefficient (S502). If the Seebeck coefficient is less than a predetermined value, it is determined that the MLCC material is defective (S503). The predetermined value of the Seebeck coefficient can be appropriately determined according to the type of the MLCC 100. For example, 600 [mu] V / K, 400 [mu] V / K, and 200 [mu] V / K.

While the foregoing has been shown and described with respect to various embodiments of the disclosure, it is to be understood that the present disclosure is not to be limited to the specific embodiments set forth hereinabove, and that the above-described embodiments are intended to cover any variations, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure. Accordingly, the technical scope of the present disclosure should be determined only by the appended claims.

100: multilayer ceramic capacitor (MLCC)
110: internal electrode 120: dielectric
310: Heating means

Claims (8)

A method for determining whether or not a multilayer ceramic capacitor (MLCC) material including a BaTiO ₃ dielectric layer is defective,
Determining whether the MLCC material is defective by measuring a voltage across both ends of the MLCC material while giving a temperature difference to both ends of the MLCC material;
Lt; / RTI >
Wherein the step of determining whether the MLCC material is defective includes:
Applying heat to one end of the MLCC material,
Measuring a voltage between the heated one end of the MLCC material and the non-heated end of the MLCC material;
When the voltage is below a predetermined value, electrons generated due to the reduction of a large amount of Ba and Ti ions in the BaTiO ₃ dielectric layer cause the electrons generated between the heated one end of the MLCC material and the non- The charge concentration difference of the MLCC material is small,
Wherein the MLCC material comprises a BaTiO ₃ dielectric layer. delete delete delete A method for determining whether or not a multilayer ceramic capacitor (MLCC) material including a BaTiO ₃ dielectric layer is defective,
Determining whether the MLCC material is defective by measuring a Seebeck coefficient of the MLCC material;
Lt; / RTI >
Wherein the step of determining whether the MLCC material is defective includes:
Applying heat to one end of the MLCC material,
Measuring the temperature difference and voltage between the heated one end of the MLCC material and the unheated other end of the MLCC material to calculate the Seebeck coefficient;
Wherein when the Seebeck coefficient is less than or equal to a predetermined value, the heated one end of the MLCC material and the non-heated one end of the MLCC material due to electrons generated by reduction of a large amount of Ba ions and Ti ions in the BaTiO ₃ dielectric layer , It is determined that the MLCC material is defective
Wherein the MLCC material comprises a BaTiO ₃ dielectric layer. delete delete delete

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