JP2007251102A - Chip type electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chip type electronic component which can inhibit the failure of short circuit between electrode terminals due to a burst of solder, thereby, a stable mounting quality can be obtained. <P>SOLUTION: The chip type electronic component includes a substrate 11, a pair of upper surface electrodes 12 located at both ends of an upper surface of the substrate 11, a functional element 13 located so as to be electrically connected with a pair of the upper surface electrodes 12, end surface electrodes 15 located on the end surfaces of the substrates 11 so as to be electrically connected with the upper surface electrodes 12, and plating layers 16 located on the surfaces of the end surface electrodes 15. It is provided that the surface roughness of the plating layer 16 is 3 μm or less. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a chip-type electronic component that suppresses a short-circuit failure between electrode terminals due to solder explosion and obtains stable mounting quality.

  Hereinafter, a conventional chip-type electronic component will be described with reference to the drawings.

  FIG. 5 shows a cross-sectional view of a conventional chip-type electronic component mounted on a circuit board.

  In FIG. 5, reference numeral 1 denotes a substrate made of alumina having a purity of about 96%. A pair of upper surface electrodes 2 made of a thick film conductive paste are provided at both ends of the upper surface of the substrate 1. A pair of backside electrodes 3 made of a thick film conductive paste are provided at both ends. A functional element 4 is provided so as to be electrically connected to the pair of upper surface electrodes 2. Reference numeral 5 denotes an end face electrode provided on the end face of the substrate 1 so as to be electrically connected to the upper face electrode 2 and the back face electrode 3. Reference numeral 6 denotes a plating layer provided on the surface of the end face electrode 5, and this plating layer 6 has a two-layer structure of a nickel plating layer and a tin plating layer.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.
JP 2002-332202 A

  In the above-described conventional chip-type electronic component, as shown in FIG. 5, the unevenness of the surface of the plating layer 6 is increased as it is affected by the unevenness of the surface of the end face electrode 5, so that the circuit board having the land pattern 7 is provided. When the chip-type electronic component was mounted on 8 to form the solder fillet 9, there was a problem that air was entrained and solder explosion occurred in the direction of the arrow.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a chip-type electronic component that can suppress short-circuit failure between electrode terminals due to solder explosion and thereby obtain stable mounting quality. To do.

  In order to achieve the above object, the present invention has the following configuration.

  The invention according to claim 1 of the present invention is a substrate, a pair of upper surface electrodes provided at both ends of the upper surface of the substrate, and a function provided so as to be electrically connected to the pair of upper surface electrodes. An element, an end face electrode provided on the end face of the substrate so as to be electrically connected to the upper face electrode, and a plating layer provided on the surface of the end face electrode, and the surface roughness of the plating layer is According to this configuration, since the surface roughness of the plating layer is set to 3 μm or less, the surface irregularities of the plating layer located at the end surface portion of the chip-type electronic component can be suppressed. As a result, it is possible to reduce air entrainment when chip-type electronic components are mounted to form a solder fillet, so that the occurrence of solder explosion can be suppressed. Defects can also be suppressed, and a stable mounting quality can be obtained.

  The invention according to claim 2 of the present invention satisfies the relationship of y ≧ 0.90x + 1.06, particularly when the surface roughness of the end face electrode is x (μm) and the thickness of the plating layer is y (μm). Thus, according to this configuration, even when the unevenness of the surface of the end face electrode is different due to the difference in the material of the end face electrode, the plating layer is formed corresponding to the surface roughness of the end face electrode. Since the required thickness is calculated and controlled, the surface irregularities of the plating layer located on the end face of the electronic component will be suppressed, and when this is done, chip-type electronic components are mounted and solder fillets are formed Since air entrainment in the soldering can be reduced, it is possible to suppress the occurrence of solder explosion, which can also suppress short-circuit defects between the electrode terminals and achieve stable mounting quality. Is.

  As described above, since the chip-type electronic component of the present invention sets the surface roughness of the plating layer to 3 μm or less, the surface unevenness of the plating layer located on the end surface portion of the chip-type electronic component can be suppressed, As a result, air entrainment when chip-type electronic components are mounted to form a solder fillet can be reduced, so that the occurrence of solder explosion can be suppressed, thereby preventing short-circuit defects between electrode terminals. It is possible to achieve an excellent effect that stable mounting quality can be obtained.

  Hereinafter, a chip-type electronic component according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a chip-type electronic component mounted on a circuit board according to an embodiment of the present invention.

  In FIG. 1, 11 is an insulating substrate made of alumina or the like having a purity of about 96%, and a pair of upper surface electrodes 12 made of a thick film conductive paste such as resin silver are provided at both ends of the upper surface of the substrate 11. Is provided. Reference numeral 13 denotes a functional element provided so as to be electrically connected to the pair of upper surface electrodes 12. In an embodiment of the present invention, a resistor made of ruthenium oxide or the like is used. Reference numeral 14 denotes a pair of back surface electrodes provided at both ends of the back surface of the substrate 11, and an end surface electrode 15 is provided on the end surface of the substrate 11 so as to be electrically connected to the back surface electrode 14 and the top surface electrode 12. . The end face electrode 15 may be formed at the same time as the back face electrode 14 is formed and electrically connected to the top face electrode 12. Reference numeral 16 denotes a plating layer provided on the surface of the end face electrode 15, and this plating layer 16 has a single-layer structure consisting of only a nickel plating layer or a two-layer structure consisting of a nickel plating layer and a tin plating layer. And so on. Here, the plating layer 16 controls the thickness of the nickel plating layer according to the uneven shape of the surface of the end electrode 15 so that the surface roughness of the first nickel plating layer is 3 μm or less. Is.

  The chip-type electronic component according to the embodiment of the present invention configured as described above is mounted by forming a solder fillet 19 on a circuit board 18 having a land pattern 17 as shown in FIG. It is.

  FIG. 2 is a characteristic diagram showing the relationship between the surface roughness of the plating layer on the end face of the electronic component and the rate of solder explosion under the conditions of a fillet size of 0.1 mm and a nickel plating layer thickness of 4 μm. The surface roughness in FIG. 2 means the maximum height Rz of the contour curve defined in JIS standard B0601, and is a result of measurement using an ultra-deep shape measuring microscope with a resolution of 0.01 μm.

  As is apparent from FIG. 2, when the surface roughness of the end face (plating layer) of the electronic component is large, the solder explosion occurrence rate is high, but the solder explosion occurrence rate decreases as the surface roughness is reduced. If the surface roughness is 3 μm or less, the solder explosion occurrence rate is 0%. In this way, if the surface roughness of the plating layer is set to 3 μm or less, it is possible to suppress the occurrence of solder explosion, thereby suppressing short-circuit defects between the electrode terminals and obtaining stable mounting quality. It is.

  FIG. 3 is a characteristic diagram showing the relationship between the surface roughness of the end electrode of the electronic component and the thickness of the nickel plating layer necessary to suppress the solder explosion under the condition of a fillet size of 0.1 mm. When the solder explosion is suppressed, the x mark indicates the case where the solder explosion has occurred.

  As is apparent from FIG. 3, when the surface roughness of the electronic component is small, solder explosion is suppressed even if the nickel plating layer is thin, but when the surface roughness of the end face electrode is large, solder explosion is caused. In order to suppress this, it is necessary to increase the thickness of the nickel plating layer. From this, it is understood that even when the surface roughness of the end face electrode of the electronic component is large, the solder explosion can be suppressed by increasing the thickness of the plating layer formed on the surface of the end face electrode.

  Here, assuming that the surface roughness of the end face electrode is x (μm) and the thickness of the nickel plating layer necessary to suppress the solder explosion is y (μm), data indicating that the solder explosion is suppressed (circle mark 4 in FIG. 3). The equation of the approximate straight line connecting points) is obtained as y = 0.90x + 1.06 using the least square method. Therefore, when the surface roughness of the end face electrode is x (μm) and the thickness of the plating layer is y (μm), the relationship of y ≧ 0.90x + 1.06 is satisfied, that is, the thickness of the nickel plating layer is 0. By setting it to .90x + 1.06 (μm) or more, the occurrence of solder explosion can be suppressed, and stable mounting quality can be obtained.

  FIG. 4 is a characteristic diagram showing the relationship between the fillet dimension on the circuit board and the thickness of the nickel plating layer necessary for suppressing solder explosion, and is measured for three levels of surface roughness of the end face electrodes.

  As is clear from FIG. 4, as the fillet size becomes smaller, solder explosion is more likely to occur. Therefore, the thickness of the nickel plating layer necessary to suppress solder explosion increases. Here, the lower limit value of the thickness of the nickel plating layer that can suppress the solder explosion, which is obtained from the data of FIG. 3, is a case where the fillet size is 0.1 mm, but the actual fillet used for mounting on the circuit board is Since the dimensions are usually 0.1 to 0.2 mm, if the thickness is equal to or greater than the lower limit of the thickness of the nickel plating layer calculated from the data of the fillet dimensions of 0.1 mm, the effect of suppressing solder explosion under normal mounting conditions Therefore, stable mounting quality can be obtained.

  In the above-described embodiment of the present invention, the resistor is described as an example of the functional element. However, the functional element is not limited to the resistor. For example, a conductor other than the resistor, Capacitor elements, inductor elements, and the like may be used. In this case as well, the same effects as those of the embodiment of the present invention can be obtained.

  The chip-type electronic component according to the present invention can reduce the entrainment of air when the solder fillet is formed by mounting, thereby having the effect of suppressing the occurrence of solder explosion, In particular, it is useful when applied to minute chip-type electronic components that require high-density mounting.

Sectional drawing of the chip-type electronic component in one embodiment of this invention Characteristic diagram showing the relationship between the surface roughness of the plating layer and the rate of solder explosion on the end face of electronic components Characteristic diagram showing the relationship between the surface roughness of the end electrodes of electronic components and the thickness of the nickel plating layer necessary to suppress solder explosion Characteristic diagram showing the relationship between the fillet size on the circuit board and the thickness of the nickel plating layer necessary to suppress solder explosion Cross-sectional view of a conventional chip-type electronic component

Explanation of symbols

11 Substrate 12 Top electrode 13 Functional element (resistor)
15 End face electrode 16 Plating layer

Claims (2)

A substrate, a pair of upper surface electrodes provided at both end portions of the upper surface of the substrate, a functional element provided to be electrically connected to the pair of upper surface electrodes, and electrically connected to the upper surface electrode A chip-type electronic component comprising an end face electrode provided on the end face of the substrate and a plating layer provided on the surface of the end face electrode, wherein the surface roughness of the plating layer is set to 3 μm or less. 2. The chip-type electronic component according to claim 1, wherein the relationship of y ≧ 0.90x + 1.06 is satisfied when the surface roughness of the end face electrode is x (μm) and the thickness of the plating layer is y (μm).

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