JP4779976B2 - Manufacturing method of electronic parts - Google Patents

Description

  The present invention relates to a method for manufacturing an electronic component.

As a method for manufacturing this type of electronic component, an ultrasonic inspection process is used to inspect the internal structure of the pellet with an ultrasonic microscope for a laminated electronic component having a pellet in which an insulating layer and a conductor layer are laminated and baked and integrated. A manufacturing method of a multilayer electronic component including the above is known (for example, see Patent Document 1).
JP-A-5-36567

  The ultrasonic inspection process described in Patent Document 1 irradiates the multilayer electronic component with ultrasonic waves and detects the intensity and time of the reflected sound wave without destroying the multilayer electronic component. It is to discover cracks that have occurred inside.

  By the way, some cracks generated inside the electronic component are caused by the electrostriction phenomenon of the dielectric material. That is, cracks may occur in the dielectric layer due to distortion (electrostriction) generated by voltage application. Cracks generated by the electrostrictive phenomenon (hereinafter referred to as electrostrictive cracks) are often extremely minute cracks of about 1 μm. For this reason, in an inspection using ultrasonic flaw detection technology, electrostriction cracks cannot be detected with high accuracy, and screening may not be performed appropriately.

  It is an object of the present invention to provide a method for manufacturing an electronic component capable of appropriately performing screening by accurately detecting the occurrence of electrostrictive cracks and improving the manufacturing yield.

  As a result of intensive investigations to achieve the above-mentioned problems, the inventors of the present invention have a laminated body in which a dielectric layer and an electrode layer are laminated. It has been found that a change is observed in the rate of change of the amount of displacement in the stacking direction of the stacked body with respect to the applied voltage, leading to the present invention.

  The present invention relates to a method for manufacturing an electronic component having a laminate in which a dielectric layer and an electrode layer are laminated, and a predetermined voltage is applied during a withstand voltage test in which a predetermined voltage is applied. While measuring the amount of displacement in the stacking direction at a predetermined position on one surface intersecting the stacking direction of the stack, and determining and screening for the occurrence of electrostriction cracks based on the rate of change of the amount of displacement with respect to the applied voltage; It is characterized by providing.

  In the present invention, during the withstand voltage test, the displacement amount in the stacking direction at a predetermined position on one surface intersecting the stacking direction of the laminate is measured while applying a predetermined voltage. Then, based on the rate of change of the measured displacement amount with respect to the applied voltage, the presence or absence of the occurrence of electrostriction cracks is judged and screened. For this reason, it is possible to accurately detect that an electrostrictive crack has occurred and perform screening appropriately. As a result, the object to be inspected in which the electrostrictive crack has occurred can be surely removed, and the manufacturing yield can be improved. Moreover, in this invention, since the displacement amount in the lamination direction of a laminated body is measured simultaneously with a withstand voltage test, a process can be simplified.

  Preferably, in the screening step, based on the SN ratio of the value obtained by second-order differentiation of the displacement amount with respect to the applied voltage, it is determined that an electrostriction crack has occurred when the SN ratio is greater than 1. In this case, when determining the presence or absence of a crack based on the rate of change of the displacement amount with respect to the applied voltage, it can be easily determined.

  Preferably, a laser displacement meter is used for measuring the amount of displacement. In this case, since the displacement amount can be measured more accurately, the presence / absence of a crack can be determined more reliably.

  According to the present invention, it is possible to provide a method of manufacturing an electronic component capable of appropriately performing screening by detecting electrostriction cracks with high accuracy and improving the manufacturing yield.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

  FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor to which the manufacturing method according to this embodiment is applied. The multilayer ceramic capacitor 1 includes a substantially rectangular parallelepiped laminate 4 in which dielectric layers 2 and internal electrode layers 3 are alternately laminated, and terminals formed on both end faces of the laminate 4 in the direction intersecting the lamination direction. Electrodes 5 and 6 are provided.

The dielectric layer 2 is made of a dielectric material such as a BaTiO ₃ system, a Ba (Ti, Zr) O ₃ system, or a (Ba, Ca) TiO ₃ system having electrostrictive characteristics, and is sandwiched between the internal electrode layers 3. The thickness of the dielectric layer 2 is reduced to, for example, 18.5 μm. The internal electrode layer 3 is made of a base metal material such as Ni or Cu or a noble metal material such as Pt or Ag, and is disposed to face the dielectric layer 2, although it varies depending on the type of dielectric material. The internal electrode layers 3 arranged to face each other are drawn out to separate end faces and are electrically connected to the terminal electrodes 5 and 6. Each of the terminal electrodes 5 and 6 is multilayered, and for example, Cu, Ni, Ag—Pd, or the like is used at a portion in contact with the stacked body 4, and Ni—Sn or the like is plated on the outside thereof.

  Then, with reference to FIG. 2, the manufacturing method of the multilayer ceramic capacitor which concerns on this embodiment is demonstrated. FIG. 2 is a diagram showing a flow of a method for manufacturing a multilayer ceramic capacitor according to the present embodiment.

  In manufacturing the multilayer ceramic capacitor 1, first, a ceramic paste for forming the dielectric layer 2 and an internal electrode paste for forming the internal electrode layer 3 are respectively prepared.

  The ceramic paste can be obtained by mixing and kneading an organic vehicle or the like with the raw material of the dielectric material constituting the dielectric layer 2. As a raw material of the dielectric material, for example, when the dielectric material is various composite oxide materials as described above, oxides, carbonates, nitrates, water of each metal atom contained in the composite oxide Combinations of oxides, organometallic compounds, and the like can be given.

  The organic vehicle includes a binder and a solvent. Examples of the binder include ethyl cellulose, polyvinyl butyral, acrylic resin, and the like. Examples of the solvent include organic solvents such as terpineol, butyl carbitol, acetone, toluene, xylene, ethanol, and methyl ethyl ketone.

  In addition to the above, the ceramic paste may contain various dispersants, plasticizers, dielectrics, glass frit, insulators and the like as necessary.

  The internal electrode paste is obtained by mixing and kneading a conductive material for forming the internal electrode layer 3 and an organic vehicle. As the conductive material, a metal material as described above is used, and various shapes such as a spherical shape and a flake shape can be applied. Moreover, it is preferable to contain an appropriate amount of an inorganic compound in the internal electrode paste as required. Thereby, at the time of baking mentioned later, the difference of the volume change of a ceramic green sheet and an internal electrode paste layer can be made small, and generation | occurrence | production of the stress resulting from this can be reduced. As a result, it is possible to suppress problems such as cracks and warpage due to this stress.

  The organic vehicle includes a binder and a solvent. Examples of the binder include ethyl cellulose, acrylic resin, polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol, polyolefin, polyurethane, polystyrene, and copolymers thereof. Examples of the solvent include terpineol, butyl carbitol, kerosene, acetone and the like.

  A plasticizer may be appropriately contained in the internal electrode paste. As the plasticizer, for example, phthalic acid esters such as benzylbutyl phthalate (BBP), adipic acid, phosphoric acid esters, glycols, and the like can be applied.

  Subsequently, after preparing the above-described ceramic paste and internal electrode paste, first, a ceramic green sheet is formed on the carrier sheet made of PET or the like by a known method such as a doctor blade method (step S1: Sheet forming process). Then, a plurality of internal electrode patterns are formed on the ceramic green sheet by a known method such as a screen printing method (step S3: internal electrode formation step).

  Subsequently, the ceramic green sheets on which the internal electrode patterns are formed are stacked in a predetermined size and stacked in a predetermined number, and pressed from the stacking direction to obtain a green stacked body (step S5: stacking / pressing step). Then, the green laminate is cut into chips of a predetermined size with a cutting machine to obtain green chips (step S7: cutting step).

Subsequently, after removing the binder contained in each part from the green chip (debinding), the green chip is fired (step S9: firing process). By this firing, a laminate 4 in which the dielectric layer 2 is formed from the ceramic green sheet and the internal electrode layer 3 is formed from the internal electrode paste layer is obtained. The binder removal can be performed by heating the green chip to about 200 to 600 ° C. in air or in a reducing atmosphere such as a mixed gas of N ₂ and H ₂ . Moreover, baking can be performed by heating the green chip after binder removal to about 1100-1300 degreeC in a reducing atmosphere, for example. And after baking of this green chip, the annealing treatment which hold | maintains at 800-1100 degreeC for 2 to 10 hours is given to the obtained baked product as needed.

  Subsequently, a conductive paste is applied and baked on both ends of the laminate 4 and further plated to form the terminal electrodes 5 and 6 (step S11: terminal electrode forming step). As the conductive paste, a metal powder mainly composed of Cu mixed with glass frit and an organic vehicle can be used. The metal powder may contain Ni, Ag—Pd, or Ag as a main component. For the plating, metal plating such as Ni, Sn, Ni—Sn alloy, Sn—Ag alloy, Sn—Bi alloy or the like can be performed. Further, the metal plating may be a multilayer structure in which two or more layers of Ni and Sn are formed, for example. As described above, a plurality of multilayer ceramic capacitors 1 having the configuration as shown in FIG. 1 are obtained.

  Subsequently, withstand voltage inspection and crack inspection are performed on the obtained multilayer ceramic capacitor 1 (inspected object) (step S13: withstand voltage and crack inspection step). Here, a withstand voltage test, that is, a predetermined test voltage exceeding the rated voltage of the multilayer ceramic capacitor is applied to examine whether there is any dielectric breakdown or damage (withstand voltage test). Further, it is examined whether or not an electrostrictive crack has occurred in the object to be inspected (crack inspection). Based on these results, the test object is screened.

  Hereinafter, the crack inspection will be described in detail with reference to FIGS. 3 and 4. FIG. 3 is a diagram showing an outline of the measuring apparatus in the withstand voltage and crack inspection process. FIG. 4 is a diagram showing the measurement position of the object to be inspected by the measuring apparatus shown in FIG. Since the withstand voltage test itself is already known, detailed description thereof is omitted.

  First, when the predetermined test voltage is applied as a withstand voltage test, the amount of displacement in the stacking direction of the object to be inspected is measured. Here, the inspection object 7 is fixed to a predetermined jig (not shown) so that the measurement surface intersecting the stacking direction of the inspection object 7 faces upward, and the external electrodes 8 and 9 are connected to the terminal electrodes 5 and 6, respectively. Are electrically connected. Next, the predetermined test voltage is applied to the device under test 7 from the power source 11 that can be boosted via the external terminals 8 and 9. The test voltage is applied at a predetermined boosting speed (for example, 100 V / sec). The predetermined boosting speed may be higher than 100 V / sec, for example, 100 V / 0.1 sec.

  Then, the displacement amount in the stacking direction on the measurement surface of the inspection object 7 is measured by the laser displacement meter 12 arranged above the inspection object 7 simultaneously with the start of the pressure increase. A commercially available laser displacement meter 12 can be used here. As shown in FIG. 4, the measurement position of the displacement is set at a substantially central portion P on the measurement surface of the inspection object 7. The measurement position of the displacement amount is not limited to the substantially central portion P1, and can be arbitrarily set. For example, the displacement measurement position may be set at a substantially corner corresponding to the side end of the internal electrode layer 3 when viewed from the stacking direction.

  Then, screening is performed by determining the presence or absence of cracks based on the change rate of the displacement amount at the substantially central portion P of the measurement surface of the inspected object 7 output by the displacement meter measuring device 13. Specifically, the SN ratio of the value obtained by second-order differentiation of the displacement at the measurement position (substantially central portion P) with respect to the applied voltage is calculated, and when the calculated SN ratio is greater than 1, electrostriction cracks occur. If the calculated S / N ratio is 1 or less, it is determined that no electrostriction crack has occurred.

  A multilayer ceramic capacitor using a dielectric material having an electrostrictive effect is known to have a dielectric layer sandwiched between internal electrodes extending in the stacking direction according to the applied voltage when a voltage is applied to a terminal electrode. Yes. Therefore, although the measurement position P is also displaced by a predetermined amount in the stacking direction according to the applied voltage, as a result of the study by the present inventors, as described later, when an electrostrictive crack occurs in the multilayer ceramic capacitor, It was found that the amount of displacement in the stacking direction with respect to the applied voltage changes specifically.

  Therefore, when a specific change is seen in the change in the amount of displacement in the stacking direction at the measurement position with respect to the applied voltage, it can be determined that an electrostrictive crack has occurred in the object to be inspected. On the other hand, when no specific change is observed in the change in the amount of displacement in the stacking direction at the measurement position with respect to the applied voltage, it can be determined that no electrostrictive crack has occurred in the object to be inspected.

  In the present embodiment, whether or not a specific change is observed in the change of the displacement amount with respect to the applied voltage in the stacking direction is obtained by second-order differentiation of the displacement amount at the measurement position (substantially central portion P) with respect to the applied voltage. Judgment is made based on the SN ratio of the values. If the S / N ratio is greater than 1, it is determined that a specific change is observed, and it is determined that an electrostrictive crack has occurred. When the S / N ratio is 1 or less, it is determined that no specific change is observed, and no electrostrictive crack has occurred. Although it is possible to judge based on the value obtained by first-order differentiation of the displacement at the measurement position with respect to the applied voltage, is it more appropriate to see a specific change if judged based on the value obtained by second-order differentiation? It can be determined whether or not.

  Subsequently, the appearance of the inspection object screened by the withstand voltage test and the presence / absence of cracks is inspected (step S15: appearance inspection step). The appearance inspection is to confirm whether or not there is a portion lacking in the appearance of the object to be inspected by a camera or visual inspection. A non-defective product inspected by visual inspection is shipped as a multilayer ceramic capacitor.

  As described above, according to the present embodiment, during a withstand voltage test, a predetermined position on one surface that intersects the stacking direction of the multilayer body 4 of the device under test 7 (multilayer ceramic capacitor 1) while applying a predetermined test voltage. The amount of displacement in the stacking direction at (substantially central portion P) is measured. Then, based on the rate of change of the measured displacement amount with respect to the applied voltage, the presence or absence of the occurrence of electrostriction cracks is judged and screened. For this reason, even if extremely small electrostrictive cracks are generated, the occurrence of the electrostrictive cracks can be accurately detected and screening can be performed appropriately. As a result, the inspected object 7 in which the electrostrictive crack has occurred can be surely removed, and the manufacturing yield can be improved.

  In the present embodiment, the displacement amount in the stacking direction of the multilayer body 4 is measured simultaneously with the withstand voltage test of the device under test 7 (multilayer ceramic capacitor 1), so a predetermined voltage is applied only to measure the displacement amount. There is no need, and the inspection process can be simplified.

  In the present embodiment, in the crack inspection process, it is determined that a crack is present when the SN ratio is greater than 1 based on the SN ratio obtained by second-order differentiation of the displacement with respect to the applied voltage. . Thereby, when determining the presence or absence of a crack based on the change rate with respect to the applied voltage of a displacement amount, it can be determined simply and more appropriately.

  In this embodiment, the amount of displacement is measured using a laser displacement meter. Thereby, since the displacement amount can be measured more accurately, the presence or absence of a crack can be determined more reliably.

  Next, the method for manufacturing an electronic component according to the present invention will be described in more detail with reference to examples. The present invention is not limited to these examples.

First, a plurality of multilayer ceramic capacitors to be inspected were obtained by the procedure described above. Here, the multilayer ceramic capacitor has a 1608 shape (length: 1.6 mm, width: 0) having a capacitance of 0.47 μF, a rated voltage of 16 V, and an interlayer thickness of 2.6 μm using a BaTiO ₂ -based high dielectric constant ceramic as a dielectric material. .8 mm, height 0.8 mm).

  Subsequently, a withstand voltage test was performed by applying a test voltage of 100 V exceeding the rated voltage of 16 V to the plurality of inspected bodies 7, and at the same time, the displacement amount of each inspected body 7 in the stacking direction was measured.

  As described above, the test voltage was applied and the displacement amount was measured using the measuring apparatus shown in FIG. 3 according to the following procedure. First, the object to be inspected 7 was fixed to the support base of the measuring apparatus by holding each terminal electrode so that the measurement surface intersecting the stacking direction of the object to be inspected 7 was facing upward by the jig, and extended from the power source 11 to the jig External terminals 8 and 9 were electrically connected. A voltage is applied to the object to be inspected 7 from the power source 11 at a voltage increase rate of 50 V / sec up to 100 V, and a laser displacement meter (LK-G10 manufactured by Keyence Corporation) 12 disposed above the object 7 to be inspected. The amount of displacement in the stacking direction on the measurement surface of the inspection object 7 was measured. The measurement was performed on a substantially central portion P of the measurement surface shown in FIG.

  FIG. 5 shows the measurement results. FIG. 5 is a diagram showing a change in displacement with respect to a test voltage. FIG. 6 shows the result of first-order differentiation of the displacement with respect to the applied voltage, and FIG. 7 shows the result of second-order differentiation of the displacement with respect to the applied voltage.

  When the cross section was observed while polishing the sample having the characteristics indicated by the solid line in FIGS. 5 to 7, it was confirmed that a crack was generated. On the other hand, when the cross section was observed while polishing the sample having the characteristics indicated by the broken line in FIGS. 5 to 7, it was confirmed that no crack was generated.

  From the above, it has been found that the presence or absence of electrostrictive cracks can be determined based on the rate of change of the amount of displacement in the stacking direction with respect to the applied voltage.

It is sectional drawing of the multilayer ceramic capacitor to which the manufacturing method which concerns on this embodiment is applied. It is a figure which shows the flow of the manufacturing method of the multilayer ceramic capacitor which concerns on this embodiment. It is a figure which shows the outline of the measuring apparatus in the withstand voltage and crack test process of the manufacturing method which concerns on this embodiment. It is a figure which shows the measurement location of the to-be-inspected object by the measuring apparatus shown in FIG. It is a diagram which shows the change of the displacement amount with respect to a test voltage. It is a diagram which shows the result of having performed the first-order differentiation with respect to the applied voltage. It is a diagram which shows the result of second-order differentiation of the displacement amount with respect to the applied voltage.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor, 2 ... Dielectric layer, 3 ... Internal electrode layer, 4 ... Laminated body, 5, 6 ... Terminal electrode, 7 ... Test object, 8, 9 ... External terminal, 11 ... Power supply, 12 ... Laser Displacement meter, 13 ... Displacement measuring instrument.

Claims (4)

A method of manufacturing an electronic component having a laminate in which a dielectric layer and an electrode layer are laminated,
A step of measuring a displacement amount in the stacking direction at a predetermined position on one surface intersecting the stacking direction of the stacked body while applying the predetermined voltage during a withstand voltage test in which a predetermined voltage is applied;
And a step of screening based on a rate of change of the displacement amount with respect to the applied voltage to determine whether or not an electrostriction crack has occurred. The method of manufacturing an electronic component according to claim 1 , wherein a laser displacement meter is used for measuring the displacement amount. The electronic component is a method of manufacturing an electronic component according to claim 1 or 2, characterized in that a multilayer ceramic capacitor, further comprising a terminal electrode disposed outside of the laminate. The dielectric layer, method for manufacturing the electronic component according to any one of claims 1 to 3, characterized in that a dielectric material having electrostrictive effects.

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