Electronic component

Abstract

To provide an electronic component with improved reliability.SOLUTION: In an electronic component 1, a second portion 37 of a diffusion prevention layer 35 extends in parallel to a principal surface 5a of a base material 5. When the electronic component 1 is surface-mounted on a mounting substrate, a conductive bonding material such as solder is interposed between electrodes 30A, 30B of the electronic component 1 and a land electrode of the mounting substrate. If a bonding surface between the diffusion prevention layer 35 and a substrate 10 is wide, a metal component of the bonding material is less likely to reach a body part 31 of the electrodes 30A, 30B through the bonding surface S. This prevents the metal component of the bonding material from diffusing into the body part 31, thereby suppressing degradation in strength of the electrodes 30A, 30B due to the diffusion.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to electronic components.

Background Art

[0002] When mounting electronic components such as semiconductor elements on a mounting substrate, good bonding between the pad electrodes of the electronic components and the land electrodes of the mounting substrate is required. If a bonding defect occurs between the pad electrodes of the electronic components and the land electrodes of the mounting substrate, in addition to an increase in contact resistance, the reliability decreases because the electronic components are likely to detach from the mounting substrate due to vibration or the like.

[0003] As one of the techniques for mounting electronic components on a mounting substrate, surface mounting technology is known (for example, Patent Document 1 below). In surface mounting technology, each pad on the surface of the electronic component mounted on the mounting substrate and each land electrode of the mounting substrate are aligned with each other, and both are joined via a conductive bonding material such as solder.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above-described surface mounting technology, if the metal component of the bonding material diffuses into the pad electrode or the land electrode, there is a risk that the desired strength cannot be achieved, and it has been difficult to achieve sufficient reliability.

[0006] One aspect of the present invention aims to provide an electronic component with improved reliability.

Means for Solving the Problems

[0007] An electronic component according to one aspect of the present invention includes a base material having an insulating film forming a main surface, a main body portion provided on the main surface of the base material and located above the main surface, a conduction portion extending from the main body portion toward the base material side and penetrating the insulating film, and a thick film electrode including a diffusion prevention layer covering the main body portion, the diffusion prevention layer having a first portion directly covering the surface of the main body portion and a second portion directly covering the main surface of the peripheral region of the main body portion and extending parallel to the main surface.

[0008] In the above-described electronic component, since the second portion of the diffusion prevention layer extends parallel to the main surface of the base material, the joining surface between the diffusion prevention layer and the base material is enlarged. Therefore, when the electronic component is surface-mounted on a mounting substrate, it is difficult for the metal component of the bonding material interposed between the thick film electrode of the electronic component and the land electrode of the mounting substrate to reach the main body portion of the thick film electrode, and a decrease in the strength of the thick film electrode due to diffusion is suppressed.

[0009] In an electronic component according to another aspect, the thickness of the diffusion prevention layer covering the portion of the main surface of the base material is greater than the thickness of the thinnest portion of the diffusion prevention layer covering the main body portion.

[0010] In an electronic component according to another aspect, a plurality of thick film electrodes are provided on the main surface of the base material. When the distance between adjacent thick film electrodes is D, the thickness of the diffusion prevention layer covering the main body portion is t1, and the length of the diffusion prevention layer covering the main surface of the base material is L, t1 < L < D / 2.

Advantages of the Invention

[0011] According to various aspects of the present invention, an electronic component with improved reliability is provided.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0014] With reference to FIGS. 1 and 2, the configuration of the electronic component according to the embodiment will be described. The electronic component 1 according to the embodiment includes a base material 5 and a pair of electrodes 30A and 30B. The electronic component 1 is, as an example, a semiconductor element, for example, an LED element or a semiconductor laser element.

[0015] The base material 5 includes a substrate 10 and an insulating film 20, and has a main surface 5a.

[0016] The substrate 10 has a flat main surface 10a. In the present embodiment, the main surface 10a is composed of a semiconductor layer.

[0017] The insulating film 20 covers the main surface 10a of the substrate 10. The insulating film 20 is a so-called passivation film. The insulating film 20 is composed of an oxide or nitride containing at least one element of Si, Al, Zr, Mg, Ta, Ti, and Y, or a resin. The insulating film 20 has a substantially uniform thickness T in the first region 11 and the second region 12 of the main surface 10a. A through hole 21 is provided in the insulating film 20. In the present embodiment, the through hole 21 has a circular shape with a diameter D1 when viewed from a direction perpendicular to the main surface 10a.

[0018] The pair of electrodes 30A and 30B are both made of a metal material, and in this embodiment, they are made of Cu. Each of the electrodes 30A and 30B is provided on the main surface 5a of the base material 5 and is a thick film electrode (pad electrode) extending in the normal direction of the main surface of the substrate 10. Each of the electrodes 30A and 30B includes a main body portion 31 and a conduction portion 32. The main body portion 31 is the portion located above the insulating film 20. In this embodiment, the main body portion 31 has a square shape when viewed from a direction orthogonal to the main surface 10a. The conduction portion 32 is the portion extending from the main body portion 31 toward the base material 5 side, and extends through the through hole 21 of the insulating film 20 to reach the substrate 10. In this embodiment, the conduction portion 32 is provided so as to completely fill the through hole 21 of the insulating film 20. Therefore, in this embodiment, the conduction portion 32 has a columnar shape with a diameter D1.

[0019] The main body portion 31 and the conduction portion 32 of the electrodes 30A and 30B can be formed by electrolytic copper plating. In this case, each of the electrodes 30A and 30B is configured to include an electrode film 33. The electrode film 33 can be made of a metal material such as Cu. The electrode film 33 integrally covers the substrate 10 and the insulating film 20. More specifically, the electrode film 33 integrally covers the main surface 5a of the base material 5 (that is, the edge of the through hole 21 on the upper surface 20a of the insulating film 20 and the main surface 10a of the substrate 10 exposed from the through hole 21) and the side surface of the through hole 21.

[0020] In this embodiment, the main body portion 31 of each of the electrodes 30A and 30B further includes a raised portion 34. The raised portion 34 is a portion that protrudes from the upper surface 30a of the main body portion 31 and is formed in an annular region corresponding to the edge of the through hole 21 of the insulating film 20.

[0021] Each of the electrodes 30A and 30B further includes a diffusion prevention layer 35 that covers the main body portion 31. The diffusion prevention layer 35 is a layer for preventing the metal components (Cu in this embodiment) of the electrodes 30A and 30B from diffusing into a conductive bonding material such as solder. The diffusion prevention layer 35 can be formed of a material containing at least one of Ni, Ta, Ti, W, Mo, Cr, Zn, In, Nb, Sn, and C. The diffusion prevention layer 35 can be formed, for example, by sputtering. The diffusion prevention layer 35 may be a single layer or may be composed of a plurality of layers. In this embodiment, the diffusion prevention layer 35 is composed of a Ni layer that directly covers the main body portion 31.

[0022] The diffusion prevention layer 35 has a first portion 36 that directly covers the surface of the main body portion 31 and a second portion 37 that directly covers the main surface 5a of the base material 5 in the peripheral region of the main body portion 31. The first portion 36 and the second portion 37 of the diffusion prevention layer 35 are formed continuously. At the outer periphery of the main body portion 31 (point P in the cross section of FIG. 2) on the main surface 5a of the base material 5 (more specifically, the upper surface 20a of the insulating film 20), the first portion 36 and the second portion 37 of the diffusion prevention layer 35 are switched. The second portion 37 extends parallel to the main surface 5a of the base material 5. As shown in FIG. 2, in the diffusion prevention layer 35 formed by sputtering, the thickness of the portion of the first portion 36 that extends in the direction along the normal direction of the main surface of the substrate 10 (for example, the portion that covers the side surface of the raised portion of the main body portion 31) can be thinner than the thickness of the portion parallel to the main surface 5a of the base material 5 (for example, the portion that covers the top of the raised portion of the main body portion 31 or the bottom of the valley between the raised portions). In this case, the first portion 36 has the thinnest thickness t1 in the portion that extends in the direction along the normal direction of the main surface of the substrate 10. In this embodiment, the thickness t2 of the second portion 37 of the diffusion prevention layer 35 (that is, the height with respect to the main surface 5a of the base material 5) is thicker than the thickness t1 of the thinnest portion of the first portion 36 (t2 > t1).

[0023] Each of the electrodes 30A and 30B further includes an antioxidant layer 38. The antioxidant layer 38 directly covers the diffusion prevention layer 35 and prevents oxidation of the diffusion prevention layer 35. The antioxidant layer 38 can be composed of an Au layer. By preventing the surface of the Au that constitutes the antioxidant layer 38 (i.e., the Ni layer) of the diffusion prevention layer 35 from oxidizing, the wettability of the diffusion prevention layer 35 with respect to a conductive bonding material such as solder is improved, and a more reliable bonding structure can be obtained.

[0024] Subsequently, with reference to FIGS. 3 to 6, the procedure for manufacturing the above-described electronic component 1 will be described.

[0025] When manufacturing the electronic component 1, first, as shown in FIGS. 3 and 4, one electrode 30A is provided on the substrate 10. FIG. 3 shows a step of forming a thick film resist 40 by lift-off in a region where the electrode 30A is to be formed on the insulating film 20 patterned on the main surface 10a of the substrate 10. FIG. 4 shows a step of forming the electrode 30A in the region exposed from the thick film resist 40. The electrode 30A is provided by sputter-depositing an electrode film 33, then forming a conduction portion 32 and a main body portion 31 by electrolytic plating using the electrode film 33, and further forming a diffusion prevention layer 35 and an antioxidant layer 38 by sputtering in the order of Ni and Au, respectively.

[0026] Subsequently, as shown in FIGS. 5 and 6, the other electrode 30B is provided on the substrate 10. FIG. 5 shows a step of exposing the region where the electrode 30B is to be formed in the thick film resist 40 by lift-off. FIG. 6 shows a step of forming the electrode 30B in the region exposed from the thick film resist 40. The electrode 30B is provided in the same manner as the electrode 30A, by sputter-depositing an electrode film 33, then forming a conduction portion 32 and a main body portion 31 by electrolytic plating using the electrode film 33, and further forming a diffusion prevention layer 35 and an antioxidant layer 38 by sputtering in the order of Ni and Au, respectively.

[0027] In the above-described electronic component 1, the second portion 37 of the diffusion prevention layer 35 extends parallel to the main surface 5a of the base material 5. Therefore, the joining surface (joining surface S in FIG. 2) between the diffusion prevention layer 35 and the substrate 10 is enlarged.

[0028] When the electronic component 1 is surface-mounted on a mounting substrate, a conductive bonding material such as solder is interposed between the electrodes 30A and 30B of the electronic component 1 and the land electrodes of the mounting substrate. If the joining surface between the diffusion prevention layer 35 and the substrate 10 is wide, it is difficult for the metal components of the bonding material to reach the main body portions 31 of the electrodes 30A and 30B through the joining surface S.

[0029] Therefore, in the electronic component 1, the situation where the metal components of the bonding material diffuse into the main body portion 31 is suppressed, thereby suppressing the decrease in the strength of the electrodes 30A and 30B due to diffusion.

[0030] Also, in the electronic component 1, in order for the diffusion prevention layer 35 to suppress diffusion, the thickness of the diffusion prevention layer 35 is preferably equal to or greater than a predetermined thickness. The thickness t2 of the second portion 37 of the diffusion prevention layer 35 can be designed to be thicker than the thickness t1 of the first portion 36. By designing the thickness t1 of the thinnest portion of the first portion 36 to be a sufficient thickness to prevent diffusion, diffusion prevention can also be achieved in the second portion 37 having a thickness t2 greater than t1, and diffusion into the main body portion 31 is more reliably suppressed.

[0031] Furthermore, in the electronic component 1, when the distance between adjacent electrodes 30A and 30B is D, the thickness of the first portion 36 of the diffusion prevention layer 35 is t1, and the length of the second portion 37 in the direction parallel to the main surface 5a of the base material 5 is L, it is designed to satisfy t1 < L < D / 2. In order for the diffusion prevention layer 35 to suppress diffusion, it is preferable to enhance the adhesion between the diffusion prevention layer 35 and the insulating film 20. For this purpose, the length L of the second portion 37 is preferably equal to or greater than a predetermined length. Also, in order to avoid a short circuit between adjacent electrodes 30A and 30B, the length L of the second portion 37 is preferably set to be shorter than half of the distance D between the electrodes 30A and 30B.

[0032] As described above, the embodiments of the present invention have been explained. However, the present invention is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the gist thereof.

[0033] For example, the formation of the electrode is not limited to electrolytic plating, and may be electroless plating or other film-forming methods (for example, sputtering film formation) or the like. Further, the cross-sectional shape of the through hole provided in the insulating film is not limited to a circular shape, and may be a polygonal shape such as a quadrangular shape or an elliptical shape. The shape of the main body portion of the electrode is not limited to a square shape when viewed from a direction orthogonal to the main surface of the substrate, and may be a circular shape, a polygonal shape, or an elliptical shape.

Explanation of Reference Numerals

[0034] 1... electronic component, 5... base material, 5a... main surface, 10... substrate, 20... insulating film, 30A, 30B... electrode, 35... diffusion prevention layer, 36... first portion, 37... second portion.

Claims

1. A substrate having an insulating film including an upper surface constituting a main surface, a main body portion provided on the main surface of the substrate and positioned above the upper surface of the insulating film, a conduction portion extending from the main body portion toward the substrate side and penetrating the insulating film through a through hole provided in the insulating film, and a thick film electrode including a diffusion prevention layer covering the main body portion are provided, wherein the diffusion prevention layer has a first portion directly covering the surface of the main body portion and a second portion directly covering the upper surface of the insulating film in a peripheral region of the main body portion and extending parallel to the upper surface to enlarge a bonding surface between the diffusion prevention layer and the insulating film, and the second portion entirely directly covers the upper surface of the insulating film, an electronic component.

2. The electronic component according to claim 1, wherein a thickness of the diffusion prevention layer in a portion covering the upper surface of the insulating film is thicker than a thickness of the thinnest portion of the diffusion prevention layer in a portion covering the main body portion.

3. A plurality of the thick film electrodes are provided on the main surface of the substrate, when a distance between adjacent thick film electrodes is D, a thickness of the diffusion prevention layer in a portion covering the main body portion is t1, and a length of the diffusion prevention layer in a portion covering the upper surface of the insulating film is L, t1 < L < D / 2, the electronic component according to claim 1 or 2.

4. The thick film electrode further includes an oxidation prevention layer covering the diffusion prevention layer from a side far from the substrate, the electronic component according to any one of claims 1 to 3, wherein the oxidation prevention layer is not interposed between the second portion of the diffusion prevention layer and the upper surface of the insulating film.

5. The electronic component according to any one of claims 1 to 4, wherein the conduction portion fills the through hole in the insulating film.

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