JP2013080875A - Electrode structure for electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode structure for an electronic component, which prevents solder erosion when a Cu plating layer and a solder layer or an Sn plating layer are formed in an electrode part, and has improved adhesion.SOLUTION: A pair of electrode parts 50 spaced apart from each other are provided on a rear surface 10b of a resistor 1, and an insulating layer 2A is provided between the pair of electrode parts 50. Each of the electrode parts 50 is constituted of an electrode layer 3 and a plating electrode layer laminated on the electrode layer 3. The plating electrode layer comprises a copper plating layer 31, a tin plating layer 32, a nickel plating layer 33, and a plating layer 34 containing tin.

Description

  The present invention relates to an electrode structure of an electronic component.

  Conventionally, in some electronic parts, Cu (copper) plating may be performed on an electrode part for the purpose of reducing the specific resistance of the electrode. When such an electronic component is mounted on a substrate, a solder layer is formed on the outermost layer of the electrode portion by plating or the like. However, since the solder is mainly composed of Sn, when the solder layer is formed, Sn is formed. So-called solder erosion occurs in which Cu is alloyed and Cu is easily taken into the solder layer.

  Therefore, for example, as disclosed in Patent Document 1, a Ni plating layer is formed on a Cu plating layer, and Sn plating is performed on the Ni plating layer. Thus, solder erosion is prevented by making the plating layer of the electrode part into a multilayer structure of Cu / Ni / Sn.

JP 2003-45702 A

  However, at the Cu-Ni interface, there is no formation of an alloy layer at the time of plating, there is also oxidation of the Cu surface, etc., causing adhesion failure between the Cu plating layer and the Ni plating layer, and when external stress is applied, The Ni plating layer sometimes peeled off.

  The present invention was devised to solve the above-described problems. When a Cu plating layer, a solder layer, and an Sn plating layer are formed on an electrode portion, it prevents solder erosion and improves adhesion. Another object of the present invention is to provide an electrode structure for an electronic component.

  In order to achieve the above object, an electrode structure of an electronic component according to the present invention is an electrode structure of an electronic component comprising an electrode layer and a plated electrode layer laminated on the electrode layer, wherein the plated electrode layer is A laminated structure including a copper plating layer, a tin plating layer formed on the copper plating layer, a nickel plating layer formed on the tin plating layer, and a plating layer containing tin formed on the nickel plating layer Is the main feature.

  In the electrode structure of the electronic component of the present invention, a plating electrode layer is laminated on the electrode layer, and the plating electrode layer is formed by sequentially laminating a tin plating layer, a nickel plating layer, and a plating layer containing tin. Have a laminated structure. In this way, by adopting a structure in which the tin plating layer is sandwiched between the copper plating layer and the nickel plating layer, the contact area between the copper plating layer and the tin plating layer is alloyed to improve adhesion, while the tin plating layer and the nickel plating layer are improved. The contact area with the layer is alloyed to improve adhesion. Therefore, the bonding between the copper plating layer and the nickel plating layer becomes strong, and peeling can be prevented. At the same time, the copper plating layer can be prevented from being eroded by the nickel plating layer.

It is sectional drawing which shows the structural example of the electronic component which has an electrode structure of this invention. It is sectional drawing which shows the structural example of the electronic component which has an electrode structure of this invention. It is a figure which shows one manufacturing process of the electronic component of FIG. It is a figure which shows one manufacturing process of the electronic component of FIG. It is a figure which shows one manufacturing process of the electronic component of FIG. It is a figure which shows one manufacturing process of the electronic component of FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. The drawings are schematic, and there may be a case where portions having different dimensional relationships and ratios are included between the drawings.

  FIG. 1 is a cross-sectional view showing a structural example of an electronic component having an electrode structure according to the present invention. A chip resistor will be described as an example of the electronic component. The chip resistor has a configuration in which a pair of electrode portions 50 spaced apart from each other are provided on the back surface 10 b of the chip-like resistor 1, and an insulating layer 2 </ b> A is provided between the pair of electrode portions 50. The resistor 1 is made of metal and is made of a single element metal or alloy.

  The electrode unit 50 includes an electrode layer 3 and a plated electrode layer laminated on the electrode layer 3. The plating electrode layer has a copper (Cu) plating layer 31, a tin (Sn) plating layer 32, a nickel (Ni) plating layer 33, and a plating layer 34 containing tin (Sn). Note that the electrode layer 3 may not be provided. In this case, the plated electrode layer is directly laminated on the lower surface of the resistor 1 in a region not covered with the insulating layer 2A.

  Here, the plating electrode layer is formed by plating, and has a laminated structure in which a tin plating layer 32, a nickel plating layer 33, and a plating layer 34 containing tin are laminated in order from the lowermost copper plating layer 31. doing. The plating layer 34 containing tin is specifically composed of a tin plating layer or a solder plating layer.

  The electrode layer 3 is composed of a conductor layer, and this conductor layer can be formed, for example, by printing a conductor paste containing a conductor such as Ag. Moreover, you may comprise by Cu plating, or you may comprise by conductor thin films, such as nichrome (Ni-Cr) by sputtering.

  The thickness of each electrode part 50 is larger than the thickness of the insulating layer 2A. The surface 10a of the resistor 1 is covered with an insulating layer 2C, and each side surface 10c of the resistor 1 is covered with an insulating layer 2B. Both end surfaces 10d of the resistor 1 are uncovered exposed surfaces.

  When the electrode unit 50 has a laminated structure as shown in FIG. 1, an alloy layer of Cu and Sn is formed in the contact area between the copper plating layer 31 and the tin plating layer 32 during the plating process, and the copper plating layer 31 and the tin plating layer 32 are formed. The adhesion of is improved. On the other hand, an alloy layer of Sn and Ni is formed in the contact area between the tin plating layer 32 and the nickel plating layer 33, and the adhesion between the tin plating layer 32 and the nickel plating layer 33 is improved. As described above, since the bonding between the copper plating layer 31 and the nickel plating layer 33 is made strong through the tin plating layer 32, peeling can be prevented.

  Moreover, the copper plating layer 31 increases the thickness of the plating electrode and reduces the resistance value of the electrode portion. The nickel plating layer 33 prevents copper erosion due to the plating layer 34 containing tin. The plated layer 34 containing tin improves solder adhesion.

  As described above, by interposing the tin plating layer 32 between the copper plating layer 31 and the nickel plating layer 33, the adhesion between the copper plating layer 31 and the nickel plating layer 33 is improved, and copper erosion due to solder is prevented. Can be prevented.

  Here, if the thickness of the tin plating layer 32 is increased, the copper plating layer 31 may be affected by the copper erosion. Therefore, the thickness of the tin plating layer 32 is that of the copper plating layer 31 and the nickel plating layer 33. It is preferable to make it smaller than any film thickness. In addition, the thickness of the tin plating layer 32 is desirably 10 μm or less.

FIG. 2 shows an example in which the electrode structure of the present invention is applied to a thick film type chip resistor. The substrate 11 is made of an insulating material such as Al ₂ O ₃ and is formed in a rectangular shape.

  The pair of electrode portions 51 includes an electrode layer 12 and a plated electrode layer laminated on the electrode layer 12. The plating electrode layer has a copper plating layer 21, a tin plating layer 22, a nickel plating layer 23, and a plating layer 24 containing tin. The electrode layer 12 consists of conductor layers, such as Ag, for example.

  The electrode layer 12 of the pair of electrode portions 51 covers both end portions of the surface of the substrate 11 and is formed over the side surface and the back surface of the substrate 11.

  A copper plating layer 21 is laminated on the electrode layer 12. A tin plating layer 22 is laminated on the copper plating layer 21, and a nickel plating layer 23 is laminated on the tin plating layer 22. On the nickel plating layer 23, a plating layer 24 containing tin is laminated as an uppermost layer.

  Since the roles and film thicknesses of the copper plating layer 21, the tin plating layer 22, the nickel plating layer 23, and the tin-containing plating layer 24 in the electrode portion 51 are the same as those in FIG.

  The resistor 13 is made of a resistor material such as ruthenium oxide, and is a part that determines the resistance value of the chip resistor. The resistor 13 is formed between the pair of electrode layers 12, and both ends of the resistor 13 cover the ends of the pair of electrode layers 12.

  The protective layer 14 covers a part of the pair of electrodes 12 and the resistor 13, and is made of, for example, glass. The protective layer 14 is formed over the entire depth direction of the substrate 11.

  Next, a method for manufacturing an electronic component including an electrode structure will be described using the chip resistor illustrated in FIG. The manufacturing process is shown in FIGS. First, a frame F is prepared in advance. The frame F has a rectangular frame-shaped support portion 19 and a plurality of plate-like portions 1A supported by the support portion 19.

  Each plate-like portion 1A is a portion that finally becomes a resistor of the chip resistor, and has a strip shape or a long rectangular shape in which the width and thickness of each portion are constant over substantially the entire length region in the longitudinal direction. The plurality of plate-like portions 1A are arranged substantially parallel to the width direction of each plate-like portion 1A via each of a plurality of slits formed in the frame F.

  In FIG. 3 (a), only four plate-like portions 1A are provided on the frame F for easy explanation, but in reality, a large number of plate-like portions 1A are provided on one frame F. It is done.

  First, as shown in FIG. 3A, an insulating layer 2C ′ is formed on the entire upward one surface 10a of each plate-like portion 1A. In the drawing, the insulating layer 2C ′ is also formed on the support portion 19, but it is not necessary to form it on the support portion 19. The insulating layer 2C ′ is formed, for example, by printing a thick film of an epoxy resin in a solid coating.

  Next, as shown in FIG. 3B, after the frame F is turned upside down, a plurality of insulating layers 2A are arranged in the longitudinal direction of each plate-like portion 1A on the surface 10b that faces upward of each plate-like portion 1A. It forms so that it may line up at regular intervals. Each insulating layer 2A has a rectangular shape having the same width as each plate-like portion 1A. Each insulating layer 2A is formed by thick film printing using the same resin and apparatus used for forming the insulating layer 2C '.

  As will be described later, an insulating layer 2B ′ is formed on the pair of side surfaces 10c of the plate-like portion 1A. As a preparation for this, as shown in FIG. Is rotated approximately 90 degrees in the direction of the arrow N1 around the axis C1 extending in the direction of. This rotation is performed by twisting and deforming the connecting portion 17. However, since the connecting portion 17 is narrower than the plate-like portion 1A, the connecting portion 17 is easily twisted and deformed, and the plate-like portion 1A can be easily rotated.

  When each plate-like portion 1A is rotated in this way, the direction of each of the pair of side surfaces 10c changes and is positioned above the front surface of the support portion 19 or below the back surface. For this reason, for example, as shown in FIG. 4D, an operation of applying the paint 2B ″ to the side surface 10c by bringing the side surface 10c of the plate-like portion 1A into contact with the liquid paint 2B ″ for forming the insulating film. It will be easy and appropriate. By drying and curing the applied paint 2B ″, as shown in FIG. 5E, an insulating layer 2B ′ is appropriately formed on the pair of side surfaces 10c of each plate-like portion 1A.

  Of course, the insulating layer 2 </ b> B ′ can be formed by a method different from that of applying a paint. After the formation of the insulating layer 2B ', each plate-like portion 1A is reversely rotated to return to the original posture. However, the subsequent electrode formation and cutting operation of each plate-like portion 1A can be performed even if each plate-like portion 1A is in a rotating state as shown in FIG. 4C, and each plate-like portion 1A. It is also possible to omit the step of returning to the original posture and reduce the total number of steps.

  Next, as shown in FIG. 5 (f), a conductor layer 3A 'is laminated in a region between the insulating layers 2A in one side 10b of each plate-like portion 1A, and then, among the plated electrode layers, A first plating electrode layer 39A ′ composed of a copper plating layer 31A ′ and a tin plating layer 32A ′ is laminated. The conductor layer 3A 'is formed by, for example, copper plating. With copper plating, it is possible to uniformly form the conductor layer 3A ′ in the region between the adjacent insulating layers 2A without creating a gap between the conductor layer 3A ′ and the insulating layer 2A. It is.

  When the conductor layer 3A 'is formed by copper plating, the copper plating layer 31A' is also formed continuously. That is, the conductor layer 3A ′ is formed so that the thickness of the conductor layer 3A ′ is equal to the total thickness of the electrode layer 3 and the copper plating layer 31 when the conductor layer 3A ′ is formed. Next, a tin plating layer 32A 'is laminated.

  The tin plating layer 32A 'is formed by a plating process. Thus, by forming the conductor layer 3A ′ and the first plating electrode layer 39A ′, a bar-shaped resistor corresponding to a configuration in which the chip resistors are integrally connected in the longitudinal direction of the plate-like portion 1A. Aggregate A ′ is obtained.

  Thereafter, as shown in FIG. 6, each bar-shaped resistor aggregate A ′ is cut at a location indicated by an imaginary line C <b> 2 and divided into a plurality of chip resistors A. Each chip resistor A includes a chip-like resistor 1 from which the plate-like portion 1A is cut, an electrode 3 from which the conductor layer 3A ′ and the first plating electrode layer 39A ′ are cut, a copper plating layer 31, and a tin plating layer. 32, the first plated electrode layer 39, the insulating layer 2A, and the insulating layers 2B and 2C obtained by cutting the insulating layers 2B ′ and 2C ′.

  Next, the nickel plating layer 33 and the plating layer 34 containing tin are sequentially laminated on the tin plating layer 32 in the first plating electrode layer 39 of each divided chip resistor A by plating. In this way, the chip resistor of FIG. 1 is completed.

  As described above, the electrode structure of the electronic component of the present invention is exemplified by the chip resistor, but is not limited to the chip resistor, and the electronic component having an electrode structure that needs to be subjected to solder plating or Sn plating. Can be applied to all.

DESCRIPTION OF SYMBOLS 1 Resistor 2A Insulating layer 2C Insulating layer 3 Electrode layer 4 Resistor 31 Copper plating layer 32 Tin plating layer 33 Nickel plating layer 34 Plating layer containing tin

Claims (3)

An electrode structure of an electronic component comprising an electrode layer and a plated electrode layer laminated on the electrode layer,
The plating electrode layer includes a copper plating layer, a tin plating layer formed on the copper plating layer, a nickel plating layer formed on the tin plating layer, and a plating layer containing tin formed on the nickel plating layer. An electrode structure of an electronic component comprising a laminated structure.   2. The electrode structure for an electronic component according to claim 1, wherein a film thickness of the tin plating layer is smaller than any film thickness of the copper plating layer and the nickel plating layer.   The electrode structure for an electronic component according to claim 1, wherein the plating layer containing tin is a tin plating layer or a solder plating layer.

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