JP2008171865A - Electronic component mounting structure of wiring board and method of detaching electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate reuse of an electronic component by facilitating attaching/detaching the component to be mounted on a substrate. <P>SOLUTION: An electrode 3a of a surface mounting component 3 as an electronic component is joined and fixed on a land 7a exposed from a protective layer 9 of a conductive member 7 provided on a wiring board 1 via a solder 11. Through holes 5a are provided near the land 7a of the wiring board 1, and a heat transfer section 13 made of plating is provided on the inner surface of each of the through hole 5a. The heat transfer section 13 has one end 13b continuing to the conductive member 7, and the other end 13c exposed on the surface opposite to the surface where the surface mounting component 3 is mounted. The exposed other end 13c is heated with a heater, heat due to heating is transferred from the heat transfer section 13 to the solder 11 via the conductive member 7, and the transferred heat melts the solder 11 to detach the surface mounting component 3 from the wiring board 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electronic component mounting structure of a wiring board in which an electrode of an electronic component is bonded to a substrate-side electrode on a wiring board via a bonding member, and a method for removing the electronic component.

  2. Description of the Related Art Conventionally, a surface mounting component (hereinafter referred to as SMD) that is an electronic component mounted on the surface of a wiring board is a land having an area substantially the same as or larger than that of an SMD electrode on the wiring board side when mounting. A part (substrate-side electrode) is formed, and a bonding member such as paste solder corresponding to the area is applied (for example, see Patent Document 1 below).

When removing the SMD from such a wiring board, there are a method in which the periphery of the SMD is directly melted with hot air or the like to melt the solder, or the electrode part of the SMD is directly heated with a soldering iron or the like.
JP-A-4-287998

  By the way, in recent years, from the viewpoint of resource saving and energy saving, 3R, which is a keyword for building an environmental society, that is, reduce (reducing waste generation), reuse (reuse), and recycle (recycle resources). ) Has been required.

  However, in the electronic component mounting structure of the conventional wiring board described above, the removal of the SMD is mostly assumed to be a new replacement due to a failure of the SMD or a correction of the solder joint due to a soldering failure. The land area opposite to the electrode of the SMD is equal to or larger than that of the electrode, and the amount of solder that is a joining member is also increased.

  For this reason, when the SMD is removed from the wiring board, the melting time of the solder becomes long, and a large amount of solder remains on the electrode of the SMD after being removed from the wiring board, making it difficult to reuse the SMD. There is an inconvenience.

  Moreover, in the conventional removal method, since heat is directly applied to the SMD, the SMD is easily damaged during removal. In order to prevent this damage, when heating is attempted from the back side opposite to the SMD mounting surface, a wiring board (base material) having poor heat conductivity is interposed between the heat source and the solder joint in the single-sided board. In the double-sided board and the multilayer board, circuit forming wiring further intervenes, so that heat for melting the solder is not directly applied to the solder joint portion, and there is a disadvantage that much time is required for removal.

  As described above, in the conventional electronic component mounting structure of the wiring board, the product design and construction method considering the 3R described above are not adopted, and it is inconvenient to reuse the SMD.

  Accordingly, an object of the present invention is to facilitate the removal of an electronic component mounted on a wiring board and facilitate the reuse of the electronic component.

  In order to achieve the above object, the present invention forms a substrate side electrode by opening a part of a protective layer covering a conductive portion on a wiring board, and provides a bonding member on the substrate side electrode. When joining the electrodes of the electronic component, one end is provided continuously to the conductive part at a position near the board-side electrode, and the other end is opposite to the mounting surface on which the conductive part of the wiring board is provided. A heat transfer portion exposed on the side surface is provided on the wiring board.

  For this reason, by heating the other end of the heat transfer part, this heat is transmitted from the substrate side electrode of the conductive part continuous to the one end of the heat transfer part to the joining member, so that the joining member melts and the electronic component is Can be removed.

  At this time, since the area of the substrate-side electrode in plan view is set smaller than the area of the electrode of the electronic component in plan view, the amount of joining members to be used is small compared to the prior art, and the necessary minimum Even after the removal, the joining member hardly remains on the electrode of the electronic component even after the removal, and the electronic component can be easily reused.

  In addition, since the heat transfer section is heated from the side opposite to the mounting surface of the electronic component, heat is not directly applied to the electronic component, and damage to the electronic component can be prevented. Since heat is directly transmitted to the joining member via the conductive portion, the joining member is quickly melted and the electronic component can be removed in a short time, and the reuse of the electronic member becomes extremely easy.

  In order to achieve the above object, according to the present invention, since the heat transfer portion is provided in the through hole that penetrates the wiring board, the inner surface of the through hole that has been widely applied conventionally is treated such as plating. Thus, it is possible to cope with through holes for imparting conductivity and blind via holes in which conductive members are embedded in the through holes, and manufacturing is easy and can be achieved at low cost.

  Furthermore, in order to achieve the above object, the present invention heats the other end portion of the heat transfer portion and melts the bonding member on the substrate side electrode included in the conductive portion continuous from the one end portion of the heat transfer portion. Since the electronic component is removed from the wiring board, the heat applied to the heat transfer portion is directly transmitted to the joining member via the conductive portion, so that the joining member is quickly melted and the electronic component is removed. It can be removed in a short time.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an electronic component mounting structure of a wiring board according to a first embodiment of the present invention, and a surface mounting component that is an electronic component on a printed wiring board (hereinafter simply referred to as a wiring board) 1. (Hereinafter referred to as SMD) 3 is implemented. 2 is a perspective view showing a state in which the SMD 3 is mounted on the wiring board 1, and FIG. 3 is a perspective view showing a state in which the SMD 3 is removed with respect to the mounting state in FIG.

  The above-described wiring board 1 is provided with a conductive member 7 as a conductive portion made of a copper foil or the like that has been processed to form a predetermined circuit pattern by etching or the like on a base material 5 made of glass epoxy material or the like. A protective layer (resist) 9 is applied so as to cover the conductive member 7 for the purpose of protecting the conductive member 7 and insulating the pattern.

  The protective layer 9 is provided with a circular opening 9a, and the portion of the conductive member 7 exposed by the opening 9a becomes a land 7a as a substrate-side electrode. Solder 11 as a joining member is provided in the opening 9a on the land portion 7a, and the electrode 3a of the SMD 3 is joined by the solder 11 so that the SMD 3 is mounted on the wiring board 1. Become.

  Here, as shown in FIG. 4 which is an enlarged plan view showing the mounting portion of the SMD 3 on the wiring board 1, the area (the hatched portion in FIG. 4) of the land portion 7a in plan view is SMD3. It is set to be sufficiently smaller than the area of the electrode 3a in plan view.

  In the SMD 3 in this embodiment, three electrodes 3a are provided on one side as shown in FIG. 2, and three electrodes 3a are provided on the side opposite to the electrode 3a. Corresponding to this, land portions 7a are also provided at six locations. The heat transfer portions 13 are provided in the vicinity of the land portions 7a between the pair of the land portions 7a in the six locations at positions facing each other in the left-right direction in FIG.

  The heat transfer part 13 is provided with a through hole 5a penetrating in the thickness direction of the base material 5 and is provided with a cylindrical part 13a set on the inner surface of the through hole 5a. Form to hold. At this time, in the heat transfer part 13, one end part 13 b on the SMD 3 side of the cylindrical part 13 a is provided continuously to the conductive member 7 at a position near the land part 7 a, and the other end part 13 c is the conductive member 7 of the wiring board 1. It is exposed on the surface opposite to the mounting surface. The other end 13c is bent outward along the surface of the base material 5 from the through hole 5a to form an annular flange shape, and the surface (the lower surface in FIG. 1) is the surface of the wiring board 5 ( In FIG. 1, the lower surface corresponds to the surface of the protective layer 15).

  In such an electronic component mounting structure of a wiring board, the electrode 3a of the SMD 3 is electrically connected to the conductive member 7 including the land portion 7a on the substrate 5 by the solder 11 provided on the land portion 7a. At the same time, it is fixedly connected mechanically.

  When the SMD 3 is removed from the wiring board 1 for reuse, for example, as shown in FIG. 5, the heat source 17 such as a heater is placed on the surface opposite to the surface on which the SMD 3 is mounted on the wiring board 1. And is brought into contact with the other end 13c of the heat transfer section 13 exposed on this surface and heated.

  The heat received by the other end portion 13c of the heat transfer portion reaches the one end portion 13b via the cylindrical portion 13a, and further reaches the solder 11 on the land portion 7a from the conductive member 7 to melt the solder 11, thereby causing the SMD 3 The electrode 3a can be separated from the solder 11 and the land portion 7a, and the SMD 3 can be detached from the wiring board 1.

  At this time, in this embodiment, as shown in FIG. 4, since the area of the land portion 7a in plan view is set to be smaller than the area of the electrode 3a of the SMD 3 in plan view, the amount of solder 11 to be used is conventional. The amount of solder 11 is small after the removal, and the amount of solder 11 is small, so that it is difficult to remain (attach) to the electrode 3a of the SMD3. Therefore, it is very easy to reuse the SMD3. Become.

  Further, when the SMD 3 is removed, the heat transfer section 13 is heated from the side opposite to the SMD 3 mounting surface of the wiring board 1, so that no heat is directly applied to the SMD 3 and damage to the SMD 3 can be prevented. In addition, the heat applied to the heat transfer section 13 at this time is directly transferred to the solder 11 via the conductive member 7 continuous to the heat transfer section 13, so that the solder 11 is quickly melted and the SMD 3 is made short time. The SMD 3 can be easily reused.

  Moreover, in this embodiment, since the heat-transfer part 13 is provided in the through-hole 5a which penetrates the base material 5 of the wiring board 1, the process of plating etc. is carried out to the inner surface of the through-hole currently generally applied widely Therefore, it is possible to cope with through holes that have conductivity, and therefore, manufacture is easy and can be achieved at low cost.

  The heater 17 serving as a heat source in FIG. 5 is in contact with the metal material as a heated metal material such as copper or aluminum, but may be configured to blow sufficiently heated hot air toward the heat transfer section 13. . When the metal material is brought into contact, it may be brought into contact with the entire surface of the wiring board 1 or may be brought into contact only with a portion corresponding to the SMD 3 to be removed.

  FIG. 6 is a cross-sectional view corresponding to FIG. 5 showing an electronic component mounting structure of a wiring board according to the second embodiment of the present invention. In this embodiment, the heat transfer portion has a blind via hole shape as compared with the first embodiment having a through hole shape.

  That is, in the second embodiment, a conical through hole 5b is provided in the base material 5 of the wiring board 1 so as to penetrate in the plate thickness direction, and a conductive, particularly heat conductive member is provided in the through hole 5b. (Conductive member) is filled, and this filling portion is referred to as a heat transfer section 19.

  In the heat transfer portion 19 described above, the one end portion 19b of the conical portion 19a, which is matched to the conical shape of the through-hole 5b, on the small diameter side on the SMD3 side contacts the conductive member 7, and the lower large diameter side in FIG. The other end portion 19c is exposed on the side opposite to the mounting surface of the SMD 3 so as to be flush with the surface of the protective layer 15.

  The other end portion 19c of the heat transfer portion 19 is provided with a circular flange-shaped portion 19d that protrudes outward from the through hole 5b along the surface of the substrate 5, and this flange-shaped portion 19d is also connected to the surface of the protective layer 15. It is exposed on the side opposite to the mounting surface of the SMD 3 so as to be on the same surface.

  Other configurations are the same as those of the first embodiment shown in FIG. 1, and the same components as those of the first embodiment are denoted by the same reference numerals.

  Also in the second embodiment, when the SMD 3 is removed from the wiring board 1 for reuse, for example, the heat source 17 such as a heater is mounted on the wiring board 1 as in the first embodiment. It is brought into contact with the surface opposite to the surface being heated, and is brought into contact with the other end portion 19c including the flange-shaped portion 19d of the heat transfer portion 19 exposed on this surface and heated.

  The heat received by the other end portion 19c of the heat transfer portion 19 reaches the one end portion 19b via the conical portion 19a, and further reaches the solder 11 on the land portion 7a from the conductive member 7 to melt the solder 11. As a result, the electrode 3a of the SMD 3 can be separated from the solder 11 and the land portion 7a, the SMD 3 can be removed from the wiring board 1, and the reuse of the SMD 3 is extremely easy as in the first embodiment. An effect can be obtained.

  In the present embodiment, the heat transfer portion 19 has a conical shape, but the same applies to a straight shape in which the one end portion 19b and the other end portion 19c have the same diameter.

  Further, in the present embodiment, the heat transfer portion 19 has a configuration in which a conductive member is filled in the through hole 5b penetrating the base material 5 of the wiring board 1, and a blind via hole shape that has been widely applied conventionally is used. Can therefore be adopted and therefore easy to manufacture and can be achieved at low cost.

  Furthermore, in 1st and 2nd embodiment, although it was set as the form which provided the one heat-transfer part 19 in one place of the land part 7a, the several heat-transfer part 19 is provided in one place of the land part 7a. Also good.

It is sectional drawing which shows the electronic component mounting structure of the wiring board concerning the 1st Embodiment of this invention. It is a perspective view of the electronic component mounting structure of the wiring board of FIG. FIG. 3 is a perspective view of a wiring board with an SMD removed with respect to the mounted state of FIG. 2. It is a top view which expands and shows the mounting site | part of SMD of FIG. It is operation | movement explanatory drawing which shows the operation | work which removes SMD from a wiring board with respect to FIG. It is sectional drawing which shows the electronic component mounting structure of the wiring board concerning the 2nd Embodiment of this invention.

Explanation of symbols

1 Printed wiring board 3 Surface mount components (electronic components)
3a Surface mount component electrodes 5a, 5b Through-holes penetrating the printed wiring board 7 Conductive member (conductive portion)
7a Substrate side electrode (land part)
9 Protective layer 11 Solder (joining member)
13, 19 Heat transfer part 13b, 19b One end part of heat transfer part 13c, 19c The other end part of heat transfer part

Claims (3)

  A protective layer is provided so as to cover the conductive part provided on the wiring board, a part of the protective layer is opened, the conductive part is exposed from the opening, a substrate side electrode is formed, and the substrate side electrode is bonded. In an electronic component mounting structure of a wiring board in which a member is provided and an electrode of the electronic component is bonded to the bonding member to mount the electronic component on the wiring board, the area of the substrate-side electrode in plan view Is set smaller than the area of the electrode in plan view, one end is provided continuously to the conductive portion in the vicinity of the substrate-side electrode, and the other end is provided to the conductive portion of the wiring board. An electronic component mounting structure for a wiring board, wherein a heat transfer portion exposed on a surface opposite to the mounting surface is provided on the wiring board.   The electronic component mounting structure for a wiring board according to claim 1, wherein the heat transfer section is provided in a through-hole penetrating the wiring board.   An electronic component removing method for removing the electronic component mounted in the electronic component mounting structure for a wiring board according to claim 1 or 2 from the wiring substrate, and heating the other end of the heat transfer unit, A method for removing an electronic component, comprising: removing the electronic component from the wiring board by melting the bonding member provided on the substrate-side electrode of the conductive portion continuous from one end of the heat transfer portion.

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