JP2007232493A - Method for testing electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for testing an electronic component, capable of also detecting a defect easily such as lacking adhesion and the like between layers in a multi-layered electrode. <P>SOLUTION: The electronic component 2 having at least a pair of electrodes is prepared. A DC resistance between the electrodes is measured to obtain an initial resistance. After measuring the initial resistance, the electronic component 2 is put in a decompression apparatus 72 so as to be exposed to a depressurized atmosphere. After exposing the electronic component 2 to the depressurized atmosphere, the atmosphere surrounding the electronic component 2 is brought to return to its normal pressure, and the DC resistance between the electrodes is measured to obtain a post-decompression resistance. The defect of the electronic component is judged by comparing the initial resistance with the post-decompression resistance. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electronic component inspection method, and more particularly to an electronic component inspection method that can easily detect defects such as insufficient adhesion between layers in a multilayer electrode.

  As shown in Patent Document 1 below, many methods are known for inspecting the sealing performance of exterior resin in electronic components. However, in the conventional inspection method, it has been difficult to detect defects such as insufficient adhesion between layers in a multilayer electrode in an electronic component such as a chip-type electronic component.

  Insufficient adhesion between layers in a multilayer electrode cannot be found only by visual inspection of the outer surface of the electrode. Moreover, it is difficult to find a defect simply by measuring the DC resistance between the electrodes.

  In particular, in the case of a coil chip component having a small size, there is a case where an electrode film must be formed after coating the outer periphery of a coil portion around which a wire is wound with a resin. In such a case, impurities such as resin residues are likely to be mixed between the outer electrode film formed after resin coating and the underlying electrode film. In such a case, the adhesion between the underlying electrode film and the outer electrode film is weakened.

Even if the adhesion between these electrode films is weak, the electrode films in the electronic component immediately after manufacture are in contact with each other, so that it is difficult to find a defect even if the DC resistance between the electrodes is measured.
JP 2005-5350 A

  The present invention has been made in view of such a situation, and an object of the present invention is to provide an electronic component inspection method capable of easily detecting defects such as insufficient adhesion between layers in a multilayer electrode.

In order to achieve the above object, an electronic component inspection method according to the present invention includes:
Preparing an electronic component having at least a pair of electrodes;
Measuring a direct current resistance between the electrodes and measuring an initial resistance value;
Exposing the electronic component after measuring the initial resistance value in an atmosphere under reduced pressure;
The electronic component after being exposed to an atmosphere under reduced pressure is returned to normal pressure, the direct current resistance between the electrodes is measured, and the resistance value after reduced pressure is measured.
The electronic component is judged to be defective by comparing the initial resistance value and the post-depressurization resistance value.

  Preferably, the electrode is a multilayer electrode, and the defect of the electronic component is delamination in the multilayer electrode.

  In the inspection method of the present invention, the electronic component after the initial resistance value is measured is exposed to an atmosphere under reduced pressure. Therefore, for example, in the case of an electrode having a defect such as insufficient adhesion between layers in a multilayer electrode, the electrode film located on the outer side expands, and a gap is increased between the inner electrode film and the inner electrode film. As a result, when the resistance value after depressurization is measured, it becomes significantly larger than the initial resistance value, and defects such as insufficient adhesion between layers in the multilayer electrode can be easily detected.

  Note that, when the electronic component is not exposed to an atmosphere under reduced pressure, even if only the initial resistance value is measured, it is not possible to distinguish between a good product and a defective product.

  Preferably, the electronic component after the initial resistance value is measured is exposed to an atmosphere under reduced pressure that is 75 kPa or more lower than atmospheric pressure, more preferably 100 kPa or more. By exposing the electronic component to such a reduced pressure atmosphere, it becomes easy to find defects such as insufficient adhesion between layers in the multilayer electrode.

  Preferably, a product group including a defective product of the electronic component is determined by comparing an average of the initial resistance values of the plurality of electronic components with an average of the resistance values after decompression. Since the average of the initial resistance value and the average of the resistance value after decompression are compared, it is difficult to identify defective electronic components, but it is possible to effectively determine a product group including defective products. Since the determination is based on the average value, it is not necessary to align and specify the electronic components before and after decompression, and the handling is easy.

  Or you may judge the defect of an electronic component separately by comparing the initial resistance value for every individual in each electronic component, and the said resistance value after pressure reduction. In that case, it is also possible to identify and eliminate only defective electronic components. However, in this method, it is necessary to specify the electronic component by aligning the electronic component before and after decompression.

  Preferably, the initial resistance value and the post-depressurization resistance value for each individual electronic component are measured in a state where the plurality of electronic components are arranged side by side on a substrate or a holding plate. In this case, the electronic component can be specified before and after decompression, and it is easy to compare the initial resistance value for each individual electronic component and the resistance value after decompression.

An electronic component manufacturing method according to the present invention includes:
Preparing a core part having a pair of flanges at both axial ends of the core part;
Forming a coil part by winding a wire around the core part; and
Forming a base electrode layer on the end face and outer periphery of the flange portion;
Forming a connecting portion of the wire on the outer periphery of the flange so as to be connected to the base electrode layer;
Forming a cavity in the outer periphery of the coil portion and the outer periphery of the flange portion;
Resin is injected into the cavity, and a resin flange covering portion covering the connecting portion of the wire located on the outer periphery of each flange to the middle, and the flange covering portion are formed integrally, covering the periphery of the coil portion A step of molding an exterior resin part to be performed;
Forming an end electrode so as to cover the outer periphery of both end portions of the exterior resin portion after the formation of the exterior resin portion and to cover a part of the outer periphery and the end surface of the base electrode layer. ,
A defect in adhesion between the end electrode and the base electrode is inspected by the inspection method.

  In the method of the present invention, the resin flange covering portion, which is a part of the exterior resin portion, does not cause poor adhesion between the end electrode and the base electrode, and the wire connecting portion located on the outer periphery of the flange is provided. A resin molded product having a structure of covering partway can be manufactured.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 is a longitudinal sectional view of a coil chip component as a surface mount electronic component according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of main parts of a mold and a part showing an example of a manufacturing process of the coil chip part shown in FIG.
FIG. 3 is a schematic diagram showing a lack of adhesion between layers in a multilayer electrode,
FIG. 4 is a schematic diagram showing a coil chip component inspection method according to an embodiment of the present invention.
FIG. 5 is a graph showing the relationship between pressure reduction time and pressure in the pressure reducing device used in the inspection method shown in FIG.
FIG. 6 is a graph showing the effect of the inspection method according to one embodiment of the present invention.
Coil chip parts

  First, a surface mount electronic component that is an object of an inspection method according to an embodiment of the present invention will be described. As shown in FIG. 1, a coil chip component 2 as a surface mount electronic component according to an embodiment of the present invention has a drum core 4 as a core portion (core material). The drum core 4 is made of a ferrite material. The drum core 4 has a core part 4 a in which a wire 10 a constituting the coil part 10 is wound along the axial direction of the core 4.

  A first flange 4b and a second flange 4c are integrally formed at the first end and the second end, which are both ends in the axial direction of the core 4a. The outer dimensions of the first flange 4b and the second flange 4c are larger than the outer diameter of the core 4a.

  The cross section of the core part 4a is not particularly limited, and may be a rectangular cross section, a circular cross section, or other cross sectional shapes. The cross-sectional shape of the first flange 4b and the second flange 4c is a square shape such as a rectangular cross section. The 1st flange 4b and the 2nd flange 4c are the same size, for example, length is about 0.82 mm and width is about 0.30 mm. Moreover, the outer diameter of the core part 4a is about 0.42 mm. The total axial length L0 of the drum core 4 (substantially the same as the total length of the component 2) L0 is about 1.637 mm.

  As shown in FIG. 1, the connecting portions 10b and 10c formed at both ends of the wire 10a constituting the coil portion 10 are connected to the base electrode layer 20 at the outer peripheral positions of the flanges 4b and 4c. The connecting portions 10b and 10c of the wire 10a are fixed to the outer circumferences of the flanges 4b and 4c by means such as thermocompression bonding after the base electrode layer 20 is formed, and these connecting connections are ensured.

  The base electrode layer 20 is an electroless Ni plating having a first layer of 1.0 to 2.0 μm and a second layer of electrolytic Ni plating having a thickness of 1.0 to 2.0 μm.

  After the base electrode layer 20 and the connecting portions 10b and 10c are connected, the outer resin portion 30 is formed by molding a resin in the outer circumferential concave portion of the core portion 4a where the coil portion 10 is formed. It does not specifically limit as resin which comprises the exterior resin part 30, An epoxy resin, a phenol resin, a diallyl phthalate resin, a polyester resin etc. are illustrated.

  The exterior resin part 30 is molded using, for example, molds 80 and 82 shown in FIG. As shown in FIG. 2, the connected drum core 4 in which the coil portion 10 is formed inside the plurality of cavities 84 formed by closing the molds 80 and 82 is connected to the first drum core 4 of the adjacent drum core 4. It arrange | positions along with an axial direction so that the end surface of the flange 4b may contact the end surface of the 2nd flange of the adjacent drum core 4. FIG.

  The molds 80 and 82 are formed with holding convex portions 86 for holding the outer periphery of the contact portion between the first flange 4b and the second flange 4c of the drum core 4 disposed adjacent to each other. A circumferential gap 88 for forming the resin flange covering portion 30a shown in FIG. The circumferential gap 88 communicates with the cavity 84, and resin is injected into the cavity 84 and molded, and the molds 80 and 82 are opened, so that the exterior resin part 30 having the flange covering part 30a shown in FIG. A plurality of integrated element bodies 5 are obtained. The four side surfaces of the exterior resin part 30 are flat surfaces.

  The outer diameter of the exterior resin portion 30 of each element body 5 is larger than the outer dimensions (the maximum outer dimensions of the core portion) of the first flange 4b and the second flange 4c, and the first flange 4b and the second flange 4c. A flange covering portion 30a having a predetermined thickness is formed on the outer periphery. The flange covering portion 30a is molded integrally with the exterior resin portion 30, and is formed so as to cover the outer periphery of the flange portions 4b and 4c from the inner side to the outer side to the middle position in the axial direction.

  The thickness of the flange covering portion 30a corresponds to the depth H1 of the step-shaped recess 50 described later. Further, the axial length of the flange covering portion 30a is determined so as to appropriately adjust the axial width (W1) of the step-shaped recess 50 described later.

  After the exterior resin portion 30 is formed, the coil chip component 2 is obtained by forming a pair of end electrodes 40 at both axial ends of the element body 5. The end electrode 40 is formed after the exterior resin part 30 is formed.

  In this embodiment, each end electrode 40 has electroless Ni plating of 1.0 to 2.0 μm for the first layer, electrolytic Ni plating of 1.0 to 2.0 μm for the second layer, and 3 for the third layer. Electrolytic Sn plating of 0.0 to 4.0 μm. The thickness of the end electrode 40 is 8 μm or less.

  Each end electrode 40 is formed in a stepped shape so as to directly cover the outer peripheral surface of the flange 4b, 4c from the end face of each flange 4b, 4c and to cover the flange covering portion 30a of the exterior resin portion 30. . Each end electrode 40 is directly connected to the base electrode layer 20 and the connecting portions 10b and 10c at the end surfaces of the flanges 4b and 4c and a part of the outer peripheral surface of the flanges 4b and 4c. Moreover, since each end electrode 40 is formed so as to cover the flange covering portion 30a of the exterior resin portion 30, a step-like recess 50 that is continuous in the circumferential direction is formed on the outer peripheral surface of each end portion 40. Is done.

  As shown in FIG. 1, the step-shaped recess 50 is formed with a predetermined width (W1) from the axial end surface of the element body 5, and the ratio (W1 / W0) to the total width (W0) of each end electrode. ) Is preferably 0.1 to 0.8, more preferably 0.3 to 0.6. By setting the ratio (W1 / W0) within the above range, the connection between the end electrode 40 and the coil connecting portions 10b and 10c is sufficiently secured, and the bonding strength between the end electrode 40 and the exterior resin portion 30 is also high. high. Moreover, the effect which suppresses a tombstone phenomenon is large by setting it as this range.

  The tombstone phenomenon means that when an electronic component is mounted on a substrate, the electronic component starts up due to an imbalance of moments generated on the solder paste surfaces of the end electrodes formed at both ends of the electronic component. This is a phenomenon that results in poor bonding.

  Further, the stepped recess 50 is formed such that the depth (H1) from the maximum outer peripheral surface dimension of each end electrode 40 is 10 to 40 μm. By setting the depth H1 within this range, the connection between the end electrode 40 and the coil connection portions 10b and 10c is sufficiently secured, and the bonding strength between the end electrode 40 and the exterior resin portion 30 is also high. Moreover, the effect which suppresses a tombstone phenomenon is large by setting it as this range. On the other hand, if the depth H1 is too deep, the maximum outer dimensions of the flange portions 4b and 4c in the drum core 4 are relatively small with a limited chip size, and the electrical performance tends to deteriorate. .

  The ratio (H1 / H0) of the depth (H1) of the stepped recess 50 to the total height (H0) of the maximum outer peripheral surface of each end electrode 40 is in the range of 0.011 to 0.045. By setting the ratio within this range, the connection between the end electrode 40 and the coil connecting portions 10b and 10c is sufficiently secured, and the bonding strength between the end electrode 40 and the exterior resin portion 30 is also high. Moreover, the effect which suppresses a tombstone phenomenon is large by setting it as this range.

  In the present embodiment, in particular, even when the chip maximum height H0 is a small coil chip component 2 having a size of 0.9 mm or less and a light weight of 5 mg or less, the end electrode 40 of the end electrode 40 is reflowed during solder reflow. Solder enters the gap between the stepped recess 50 formed on the bottom surface and the substrate 60. Since the step-shaped recess 50 is formed continuously in the circumferential direction of the end electrode 40, a sufficient amount of solder can be secured. As a result, the so-called tombstone phenomenon can be effectively prevented and mounting defects can be prevented.

  For example, in the conventional coil chip component (there is no stepped recess 50), the tombstone phenomenon occurred at a ratio of about 10 per 100,000, whereas the embodiment of the present invention (the stepped recess 50) In some cases, no tombstone phenomenon occurred.

  Further, in the present embodiment, since the solder wraps around the stepped concave portion 50, sufficient bonding strength can be obtained even if the size of the fillet formed by the solder is reduced, and high-density mounting becomes possible.

  In the present embodiment, the stepped recess 50 is formed by forming the end electrode 40 so as to cover the outer periphery of both ends of the exterior resin part 30 having an outer dimension larger than the maximum outer dimension of the flanges 4b and 4c. It is formed. For this reason, it is not necessary to process the flange itself, the volume of the flange does not decrease, and the performance as a coil chip is not affected at all. Moreover, since the stepped recess 50 can be formed by resin molding, the manufacturing process is not complicated.

  Furthermore, in this embodiment, the axial width W0 of each end electrode 40 shown in FIG. 1 is preferably 0.41 mm, so that the flat surface of the exterior resin portion 30 located between the edges of the end electrode 40 is provided. The axial width L1 of 30b can be about 0.817 mm. The axial width L1 of the flat surface 30b is 30 to 70% of the total length L0 of the component 2.

The upper flat portion 30b of the exterior resin portion 30 having such an axial length L1 can be favorably sucked and held by the suction nozzle. In addition, since the thickness of the end electrode 40 is as thin as 8 μm or less, even if the end of the suction nozzle is positioned on the end electrode 40, the suction action is not reduced so much by the suction nozzle, and the part can be mounted with sufficient suction force Can be held.
Inspection method of coil chip parts

  In the electronic component such as the coil chip component 2 described above, both the base electrode layer 20 and the end electrode 40 are formed of multilayer electrodes. In addition, in the manufacturing process of the coil chip component 2, the exterior resin 30 formation step is inserted between the base electrode layer 20 formation step and the end electrode 40 formation step. Therefore, as shown in FIG. 3, impurities 31 such as the remaining resin burrs are likely to enter particularly between the base electrode layer 20 and the end electrode 40.

  If the impurity 31 enters between the base electrode layer 20 and the end electrode 40, the adhesion between them is reduced, and there is a possibility that problems such as poor conduction may occur due to long-term use. However, it has been difficult to inspect the adhesion failure between the multilayer electrodes from the appearance. Moreover, it was difficult to inspect the adhesion failure between the multilayer electrodes even by a simple continuity test.

  Therefore, in the present embodiment, problems such as poor conduction that may occur in the future due to long-term use are easily detected by the following method.

For example, 20 products are sampled out of the coil chip parts 2 manufactured by the above-described method for each production lot, and are aligned on a printed circuit board or a simple holding plate 70 as shown in FIG. The DC resistance R _DC of each coil chip component 2 is measured under atmospheric pressure. The measured DC resistance R _DC is stored as an initial resistance value R _DC i in the memory of the inspection apparatus individually for each of the aligned coil chip components 2. The direct current resistance R _DC is obtained by measuring the electrical resistance between the pair of terminal electrodes 40 shown in FIG. 1 using a resistance measuring instrument.

  Next, the coil chip component 2 arranged on the holding plate 70 is put into the decompression device 72, and the periphery of the coil chip component 2 is exposed to an atmosphere under reduced pressure. In the decompression device 72, for example, as shown in FIG. 5, the inside of the device 72 is made 75 kPa or more lower than the atmospheric pressure and more preferably 100 kPa or more lower in about 10 to 60 seconds. When the pressure is lowered by 75 kPa or more, defective products (defective products) can be detected. The holding time for reduced pressure is not particularly limited, but is preferably about 30 seconds to 5 minutes.

Thereafter, the coil chip component 2 is taken out from the decompression device 72 together with the holding plate 70, and the DC resistance R _DC of each coil chip component 2 is measured again under atmospheric pressure. The DC resistance R _DC measured after the decompression process is individually stored in the memory for each of the aligned coil chip components 2 as a resistance value R _DC f after decompression.

Thereafter, the judgment means (CPU) of the inspection device compares the post-depressurization resistance value R _DC f with the initial resistance value R _DC i for each coil chip component 2. For example, the following calculation is performed to measure the change rate C (%).
C = (R _DC f−R _DC i) * 100 / R _DC i

  In the present embodiment, for example, a change rate of 1% or more can be determined as an adhesion failure between layers in a multilayer electrode. In addition, in the method of the present embodiment, the coil chip components 2 are arranged on the holding plate 70 before and after the decompression process, so that the coil chip components 2 that cause poor adhesion can be identified and become defective. It is also possible to specify only electronic components and eliminate or reprocess them.

In the inspection method of the present embodiment, the coil chip component 2 after measuring the initial resistance value is exposed to an atmosphere under reduced pressure. Therefore, for example, in the case of an electrode having a defect such as insufficient adhesion between layers in the multilayer electrodes 20 and 40, the end electrode 40 located on the outer side swells, and a gap increases with the inner base electrode layer. As a result, when the resistance value R _DC f after decompression is measured, the resistance value R _DC f becomes significantly larger than the initial resistance value R _DC i, and defects such as insufficient adhesion between layers in the multilayer electrode can be easily detected.

The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention.
For example, in the inspection method according to the above-described embodiment, the coil chip component 2 is aligned on the holding plate 70. However, in the present invention, the coil chip component 2 is not necessarily aligned. For example, a plurality of coil chip components 2 after measuring the initial resistance value R _DC i are put in a net, the net is put in the decompression device 72 and exposed to a decompressed atmosphere, and then the atmospheric pressure under retrieves the coil chip component 2 from the network, it may be measured respectively after depressurization resistance R _{DC f.}

In this embodiment, the average value of the initial resistance value R _DC i and the average value of the resistance value R _DC f after decompression are calculated, and the average value of the rate of change C (%) is calculated in the same manner as described above. Ask for. For example, in 20 samples (normal products) that do not contain any defective products (defective products), as shown in Table 1, the rate of change of each sample is 1% or less, and the rate of change is also 1%. It is as follows.

  On the other hand, for example, in 20 samples including defective products (defective products), as shown in Table 1, the rate of change of each sample is 1% or more samples, 3% or more samples, Samples of 5% or more and samples of 10% or more are included, and the rate of change thereof is 3% or more. In Table 1, what plotted the average value of the change rate is shown in FIG.

  As shown in Table 1 and FIG. 6, it can be determined that the average value of the rate of change is 3% or more, for example, as a poor adhesion between layers in the multilayer electrode. In addition, in the method of the present embodiment, the coil chip components 2 can be arranged randomly before and after the decompression process, so that the coil chip components 2 are easy to handle. In this embodiment, the coil chip component 2 that becomes a close contact failure cannot be specified, but it is also possible to specify and exclude or reprocess a group of samples including a defective electronic component.

  Moreover, the specific cross-sectional structure of the electronic component according to the present invention is not limited to the embodiment shown in FIG. Furthermore, in the present invention, the material of the multilayer electrode and the electrode forming method are not particularly limited. For example, the base electrode layer 20 may be an electrode layer formed by baking an Ag paste or an Ag—Pd paste, and the end electrode 40 is an electrode such as Cu or Ni formed by electrolytic plating or sputtering. You may comprise.

FIG. 1 is a longitudinal sectional view of a coil chip component as a surface mount electronic component according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of main parts of a mold and a part showing an example of a manufacturing process of the coil chip part shown in FIG. FIG. 3 is a schematic diagram showing a lack of adhesion between layers in a multilayer electrode. FIG. 4 is a schematic view showing a coil chip component inspection method according to an embodiment of the present invention. FIG. 5 is a graph showing the relationship between pressure reduction time and pressure in the pressure reducing device used in the inspection method shown in FIG. FIG. 6 is a graph showing the effect of the inspection method according to one embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Coil chip component 4 ... Drum core 4a ... Core part 4b ... 1st flange 4c ... 2nd flange 5 ... Element main body 10 ... Coil part 10a ... Wire 10b, 10c ... Connection part 20 ... Underlayer electrode layer 30 ... Exterior resin Part 30a ... Flange coating part 30b ... Flat surface 31 ... Impurity 40 ... End electrode 50 ... Stepped recess 60 ... Substrate 70 ... Holding plate 72 ... Decompression device 80, 82 ... Mold 84 ... Cavity 86 ... Holding convex part 88 … Circumferential clearance

Claims (6)

Preparing an electronic component having at least a pair of electrodes;
Measuring a direct current resistance between the electrodes and measuring an initial resistance value;
Exposing the electronic component after measuring the initial resistance value in an atmosphere under reduced pressure;
The electronic component after being exposed to an atmosphere under reduced pressure is returned to normal pressure, the direct current resistance between the electrodes is measured, and the resistance value after reduced pressure is measured.
A method of inspecting an electronic component, comprising: determining a defect of the electronic component by comparing the initial resistance value and the reduced resistance value.   The method for inspecting an electronic component according to claim 1, wherein the electrode is a multilayer electrode, and the defect of the electronic component is delamination in the multilayer electrode.   3. The method of manufacturing an electronic component according to claim 1, wherein the electronic component after the initial resistance value is measured is exposed to an atmosphere under reduced pressure that is 75 kPa or more lower than atmospheric pressure.   2. The product group including a defective product of the electronic component is determined by comparing an average of the initial resistance values of the plurality of electronic components and an average of the resistance values after decompression. The inspection method of the electronic component in any one of -3.   4. The electronic component according to claim 1, wherein a defect of the electronic component is individually determined by comparing an initial resistance value for each individual electronic component and the resistance value after the pressure reduction. Inspection method. 6. The electronic component inspection according to claim 4, wherein the initial resistance value and the post-depressurization resistance value of each electronic component are measured in a state where the plurality of electronic components are arranged side by side on a substrate or a holding plate. Method.

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