JP2969666B2 - Manufacturing method of multilayer ceramic capacitor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer ceramic capacitor used for an electronic device circuit.

2. Description of the Related Art Multilayer ceramic capacitors already occupy an indispensable position as electronic circuit components. Speaking of multi-layer ceramic capacitors, chip-type capacitors occupy an overwhelming majority at present, and the image of a resin-coated type with lead wires, which was once the mainstream, has become smaller. However, in both cases, the structure of the element body is the same, and the manufacturing method is currently being performed by the same method.

The most typical method for manufacturing a multilayer ceramic capacitor is as follows. First, an organic binder and a solvent are added to a powder mixture containing barium titanate or titanium oxide as a main component.
Add plasticizer, mix and disperse slurry to 20-100μ
It is molded into a sheet having a thickness of m. Palladium or an alloy paste of silver and palladium is screen-printed on the sheet in a predetermined shape. Then, a plurality of these sheets are superimposed, and several sheets without screen printing are superimposed on the upper and lower sides of the sheets. Thereafter, the chip is cut into chip pieces to produce a green chip. After removing organic substances at a low temperature of 200 to 300 ° C, the green chip is sintered at a high temperature of 1300 to 1400 ° C to change into a sintered body. After that, the conductive layer is exposed on the end face at the same time as removing the burr by barrel polishing, and silver or silver-palladium alloy paste is applied to this end face and baked at 800 to 900 ° C. to laminate. A ceramic capacitor body is obtained. In the case of the chip type, in many cases, the terminal electrode is plated with nickel plating, tin plating, or the like as it is. On the other hand, in the case of a resin-coated type having a lead wire, a lead wire is soldered to a terminal portion, and an epoxy resin or the like is applied only to the element body portion.

As described above, the sintered body constituting the element body of the multilayer ceramic capacitor is a structure in which the metal conductor layer and the ceramic dielectric layer are integrally sintered, and has a structure in which different layers are in contact with each other. ing. Therefore, the bonding surface has a weak bonding force, and a large number of element bodies may have a state in which the bonding surface is separated, that is, a so-called delamination. There are various modes for such delamination, and depending on the mode, if incorporated into an electronic circuit, the long-term quality may not be guaranteed depending on the surrounding environment and the usage conditions of the electronic device. In an extreme case, delamination may be a source of destruction due to heat during soldering, particularly in chip-type multilayer ceramic capacitors during mounting, causing cracks and short-circuit failure.

Problems to be Solved by the Invention Conventionally, non-destructive selection methods such as X-ray fluoroscopy and ultrasonic flaw detection have been attempted for this delamination, and a great many documents have been submitted. However, although there is an effect as a sampling inspection method, there are still many problems in terms of mass processing as a method of selecting all of them, and they have not yet been put to practical use. Accordingly, at present, lot acceptance / rejection determination is performed by the sampling inspection method.

An object of the present invention is to provide a method for manufacturing a multilayer ceramic capacitor of good quality by effectively removing the presence of delamination in the above-described multilayer ceramic capacitor.

Means for Solving the Problems In order to solve this problem, the present invention measures the difference in insulation resistance value by applying a pulse voltage to all of the multilayer ceramic capacitors and causing the delaminated portion to break down. , A multilayer ceramic capacitor having a delamination is removed.

According to such a method of the present invention, it is possible to easily carry out 100% sorting, and because there are a few defective defective products, which have been found in the conventional lot inspection, many non-defective products are mixed. Can be saved, so that manufacturing loss can be reduced.

Examples Hereinafter, the present invention will be described in detail based on examples.

First, a multilayer ceramic capacitor in which delamination occurred was obtained as a mass-produced product, and a sample in which four delaminations were confirmed for every thirty samples extracted in a cross-sectional inspection result was used. From this sample, 1000 pieces were taken out, and an ultrasonic flaw detector was used to separate what was observed when delamination was present from what was not. As a result,
116 possible delaminations
There were 792 pieces that were deemed to be free of delamination, and 92 pieces were neither. As a result of observing 30 cross sections of each of these classifications, some of them included a mode of delamination as shown in FIG. 1, and they showed the quantity ratio as shown in Table 1 below.

In FIG. 1, 1 is a ceramic dielectric layer, 2 is a conductor layer, and 3 is a terminal electrode.

Next, from the classification that seems to have no delamination
10 pieces are extracted and the rise time is 1μsec with a pulse tester.
Pulse voltage was applied. At this time, while monitoring the voltage between the sample terminals with an oscilloscope, the pulse application was repeated while increasing the pulse voltage until the pulse waveform abnormally attenuated, and the changed voltage value (peak value) was obtained. As a result, at 800 volts, all ten pulse waveforms changed. FIG. 2 shows this waveform change pattern. In the figure,
(A) shows that the pulse waveform does not change normally,
(A) shows abnormal attenuation of a typical pulse waveform. Therefore, 10 samples were extracted from the class that seems to have delamination, and a test similar to the above was performed.
Above volt, all 10 pulse waveforms attenuated abnormally.

Therefore, we fixed the peak value of the pulse voltage to 500 volts,
100 samples were extracted from the sample population, and a pulse was applied to all the samples. The samples were classified into those with abnormally attenuated pulse waveforms and those with normal pulse waveforms. Table 2 below shows the results of measuring the electrical characteristics of the normal and abnormal products of the pulse waveforms after the classification, and comparing the unchecked products with the confirmation quantities for each mode of delamination by cross-sectional observation.

As is clear from the results in Table 2, it is clear that by applying a pulse voltage, a multilayer ceramic capacitor having a delamination can be detected by monitoring the pulse waveform with an oscilloscope. It is clear that the resistance value decreases. Therefore, by confirming in advance in a preliminary test the peak voltage at which the pulse voltage waveform of the normal product of the target multilayer ceramic capacitor causes abnormal attenuation, a pulse voltage less than the peak value is applied to the sample, and the difference in insulation resistance As long as it is detected, it can easily remove delaminations,
It is possible to take out only normal products.

Effect of the Invention As described above, the present invention provides a multilayer ceramic capacitor having at least delamination by applying a pulse voltage to all of the multilayer ceramic capacitors in which a plurality of ceramic dielectric layers and conductive layers are alternately stacked. The present invention comprises a first step of dielectric breakdown of a capacitor, and a second step of separating and removing the multilayer ceramic capacitor having the dielectric breakdown by measuring the insulation resistance after the first step. According to the method, by applying the pulse voltage in the first step, at least the multilayer ceramic capacitor having the delamination is broken down, and then in the second step, the difference between the insulation resistance value and the normal product is detected. Normal products and abnormal products are separated, the multilayer ceramic capacitor with delamination is removed, and only normal products are selected. Can be different.

In this case, the pulse voltage application in the first step can be performed in a short time because it is only necessary to apply the pulse voltage without forming a high temperature atmosphere higher than the maximum use temperature, and the application of the pulse voltage causes delamination. Although the insulation breakdown is surely performed, the insulation resistance is measured in the second step.
Normal products can be easily separated and only normal products can be selected.

Therefore, it is possible to select a large number of multilayer ceramic capacitors in a very short time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining the detection result of delamination and the mode of delamination by ultrasonic flaw detection of a sample used in an embodiment of the present invention, and FIG. FIG. 7 is a diagram illustrating abnormal attenuation of a pulse waveform used for detecting delamination for explanation. 1 ... ceramic dielectric layer, 2 ... conductor layer, 3 ... terminal electrode.

Continued on the front page (72) Inventor Takayoshi Tomi 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-61-96475 (JP, A) .Cl. ⁶ , DB name) H01G 4/12 364

Claims (1)

(57) [Claims] 1. A multilayer ceramic capacitor comprising a plurality of ceramic dielectric layers and a plurality of conductive layers alternately stacked,
A first step of applying a pulse voltage to cause dielectric breakdown of at least the multilayer ceramic capacitor having delamination; and, after the first step, measuring the insulation resistance to separate the multilayer ceramic capacitor that has undergone dielectric breakdown, A method for manufacturing a multilayer ceramic capacitor, comprising: a removing step.