JP2015130424A - Printed wiring board, printed circuit board and printed circuit board manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board in which location accuracy of a light emitting diode is high; and to provide a printed circuit board using the printed wiring board and a printed circuit board manufacturing method.SOLUTION: A printed wiring board includes an insulating base film, and a conductive pattern which is laminated on a surface of the base film and has a plurality of land parts and wiring parts, in which a plurality of light emitting diodes are mounted on the plurality of land parts via solder. The land parts are laminated, in planar view, on connection scheduled regions of connection terminals of the light emitting diodes which are connection targets of the land parts, and on peripheral regions which lead to outer edges of the connection scheduled regions; an average width of the peripheral regions is not less than 10 μm and not more than 50 μm. It is preferable that one or a plurality of wiring parts are connected to the land part and a total projection width of the one or the plurality of wiring parts to one side of the land part is not greater than 20% of a length of the one side.

Description

  The present invention relates to a printed wiring board, a printed circuit board, and a printed circuit board manufacturing method.

  An optical transmitter used in an optical information transmission system or the like that transmits information with an optical signal has a configuration in which an incident end face of an optical fiber is opposed to a light emitting diode mounted on a printed wiring board via solder, for example. (Refer to Unexamined-Japanese-Patent No. 2005-12845).

JP 2005-12845 A

  In such an optical transmitter, since the light from the light emitting diode is incident on the optical fiber, the positional accuracy between the light emitting diode and the optical fiber is important. However, when the light emitting diode is soldered to the printed wiring board by reflow or the like, the solder easily flows on the land portion, so that the light emitting diode moves from the light emitting diode as the solder flows on the land portion of the printed wiring board. May not be sufficiently incident on the optical fiber.

  The present invention has been made based on the above situation, and provides a printed wiring board with high positional accuracy of a light emitting diode, a printed circuit board using the printed wiring board, and a method for manufacturing the printed circuit board. For the purpose.

  The invention made in order to solve the above-mentioned problems comprises a base film having an insulating property, and a conductive pattern laminated on the surface of the base film and having a plurality of land portions and wiring portions. A printed wiring board on which one or a plurality of light emitting diodes are mounted via solder, and the land portion is a plan connection region of connection terminals of the light emitting diodes to be connected in plan view, and the connection planned region And a printed wiring board having an average width of 10 μm or more and 50 μm or less.

  Another invention made to solve the above problems is a printed circuit board including the printed wiring board and one or more light emitting diodes mounted on a plurality of land portions of the printed wiring board.

  Furthermore, another invention made in order to solve the above-mentioned problems is a base film having an insulating property, a conductive pattern laminated on the surface of the base film and having a plurality of land portions and wiring portions, and the plurality of lands. A method of manufacturing a printed circuit board comprising one or a plurality of light emitting diodes mounted on a part via solder, the step of forming a conductive pattern having a plurality of land parts and a wiring part on the surface of the base film; Mounting one or a plurality of light emitting diodes on the plurality of land portions via solder. In the conductive pattern forming step, the land portions are connected to the light emitting diodes to be connected in plan view. It is laminated on a terminal connection planned region and a peripheral region continuous to the outer edge of the planned connection region, and the average width of the peripheral region is 10 μm or more and 50 μm or less. A method for producing a printed circuit board.

  The printed wiring board, printed circuit board, and printed circuit board manufacturing method of the present invention can increase the positional accuracy of the light emitting diode. Therefore, it can be suitably used for an optical information transmission system.

FIG. 1A is a schematic plan view of a printed wiring board according to an embodiment of the present invention. FIG. 1B is a schematic end view taken along line X1-X1 of FIG. 1A. FIG. 2 is a schematic plan view of the conductive pattern of the printed wiring board according to the embodiment of the present invention. FIG. 3A is a schematic plan view of a printed circuit board according to an embodiment of the present invention. FIG. 3B is a schematic end view taken along line X2-X2 of FIG. 3A. FIG. 4 is a schematic plan view of a conductive pattern of a printed wiring board according to an embodiment different from the printed wiring board of FIG. FIG. 5 is a schematic plan view of a conductive pattern of a printed wiring board according to an embodiment different from the printed wiring board of FIG.

[Description of Embodiment of Present Invention]
The present invention comprises an insulating base film and a conductive pattern laminated on the surface of the base film and having a plurality of land portions and wiring portions, and one or a plurality of the plurality of land portions via solder. A printed wiring board on which a light emitting diode is mounted, wherein the land portion is a plan connection region of a connection terminal of a light emitting diode to be connected and a peripheral region continuous to an outer edge of the connection planned region And a printed wiring board having an average width of the edge region of 10 μm to 50 μm.

  As described above, for example, in a printed wiring board used as an optical transmitter of an optical information transmission system, the positional accuracy of a light emitting diode to be mounted is important. The position accuracy of the light emitting diode is required to be within 0.1 mm as an error from the design position, for example. On the other hand, the printed wiring board can reduce the distance that the light-emitting diode moves due to the flow of solder during soldering by setting the average width of the edge region within the above range. As a result, the error from the design position of the light emitting diode is expected to be within 0.1 mm. As a result, the positional accuracy of the light emitting diode is increased.

  It is preferable that the connection planned area is substantially rectangular and the land portion is substantially rectangular in plan view. As described above, the land portion can be easily formed by making the connection scheduled region and the land portion substantially rectangular. In addition, when the connection planned region and the land portion are substantially rectangular, positioning at the time of disposing the light emitting diode is facilitated.

  One or more wiring parts are connected to the land part, and the total projected width of one or more wiring parts with respect to one side of the land part is preferably 20% or less of the length of one side. Thus, by making the total projected width of one or a plurality of land portions with respect to one side of the land portion not more than the above upper limit, the distance that the light emitting diode moves due to the flow of solder from the land portion to the wiring portion during soldering Can be further reduced. This further increases the positional accuracy of the light emitting diode.

  The wiring part may be connected to a corner part of the land part. By connecting the wiring portion to the corner portion of the land portion in this way, the distance that the light emitting diode moves due to the flow of solder from the land portion to the wiring portion during soldering can be further reduced. This further increases the positional accuracy of the light emitting diode.

  It is preferable that the base film has flexibility. Thus, since the said base film has flexibility, the said printed wiring board can be used as a flexible printed wiring board.

  Moreover, this invention includes a printed circuit board provided with the said printed wiring board and the 1 or several light emitting diode mounted in the several land part of this printed wiring board.

  Since the printed circuit board includes the printed wiring board, the positional accuracy of the light emitting diode can be increased.

  Furthermore, the present invention provides a base film having insulating properties, a conductive pattern laminated on the surface of the base film and having a plurality of land portions and wiring portions, and mounted on the plurality of land portions via solder 1 Or a method of manufacturing a printed circuit board comprising a plurality of light emitting diodes, the step of forming a conductive pattern having a plurality of land portions and wiring portions on the surface of the base film, and soldering the plurality of land portions through solder. Mounting one or a plurality of light emitting diodes, and in the conductive pattern forming step, the land portion is, in plan view, a connection planned region of a connection terminal of the light emitting diode that is a connection target, and the connection planned And a printed circuit board manufacturing method in which the average width of the edge region is 10 μm or more and 50 μm or less. Mu

  In the method of manufacturing the printed circuit board, the distance that the light emitting diode moves during soldering can be reduced by setting the average width of the edge region within the above range. As a result, the error from the design position of the light emitting diode is expected to be within 0.1 mm. As a result, a printed circuit board with high positional accuracy of the light emitting diode can be manufactured.

  Here, the “average width of the edge region” means a value obtained by averaging the shortest distances to the outer edge of the edge region at each point of the outer edge of the planned connection region. Further, the “substantially rectangular” is a concept including not only a physically exact rectangle but also a rectangle that can be regarded as a rectangle in view of technical common sense. The “projection width of the wiring portion” means a length along one side of a connection portion between the wiring portion and one side of the land portion.

[Details of the embodiment of the present invention]
Hereinafter, an embodiment of a printed wiring board according to the present invention will be described in detail with reference to the drawings.

[First embodiment]
1A and 1B includes a base film 1 having flexibility and electrical insulation, and a conductive pattern laminated on the surface of the base film 1 and having a plurality of land portions 2 and a plurality of wiring portions 3. 4. One or more light emitting diodes are mounted on the plurality of land portions 2 via solder.

<Base film>
The base film 1 is composed of a sheet-like member having flexibility and electrical insulation. Specifically, a resin film can be employed as the base film 1. As a material for this resin film, for example, polyimide, polyethylene terephthalate or the like is preferably used.

  As a minimum of average thickness of base film 1, 5 micrometers is preferred and 10 micrometers is more preferred. When the average thickness of the base film 1 is less than the above lower limit, the strength of the base film 1 may be insufficient. On the other hand, the upper limit of the average thickness of the base film 1 is preferably 100 μm, and more preferably 50 μm. When the average thickness of the base film 1 exceeds the upper limit, the printed wiring board may be unnecessarily thick.

<Conductive pattern>
The conductive pattern 4 is formed in a desired planar shape (pattern) by etching a metal layer laminated on the surface of the base film 1. The land portion 2 is a portion to which the terminals of the light emitting diode are connected, and the wiring portion 3 is formed so as to connect the plurality of land portions 2.

  The conductive pattern 4 can be formed of a conductive material, but is generally formed of copper, for example.

  The lower limit of the average thickness of the conductive pattern 4 is preferably 5 μm, and more preferably 8 μm. On the other hand, the upper limit of the average thickness of the conductive pattern 4 is preferably 50 μm, and more preferably 35 μm. When the average thickness of the conductive pattern 4 is less than the above lower limit, the conductivity may be insufficient. Conversely, when the average thickness of the conductive pattern 4 exceeds the upper limit, the printed wiring board may impair flexibility.

<Land part>
The land portion 2 is stacked in a plan connection region R1 of a connection terminal of a light emitting diode that is a connection target and a peripheral region R2 that is continuous with the outer edge of the connection region in plan view. The edge region R2 is a region that allows a positional shift when the connection terminal of the light emitting diode is disposed in the connection planned region R1.

  As described above, for example, in a printed wiring board used as an optical transmitter of an optical information transmission system, the positional accuracy of a light emitting diode to be mounted is important. The position accuracy of the light emitting diode is required to be within 0.1 mm as an error from the design position, for example. On the other hand, since solder tends to flow in the land portion 2 during soldering, the light emitting diode may move in the land portion 2. On the other hand, it is difficult for the solder to flow on the surface of the base film 1 where the land portion 2 (conductive pattern 4) is not formed. Therefore, by appropriately determining the range of the average width L of the edge region R2, the distance that the light emitting diode moves during soldering can be reduced.

  The lower limit of the average width L of the edge region R2 is 10 μm, preferably 15 μm, and more preferably 20 μm. When the average width of the edge region R2 is less than the lower limit, when the light emitting diode is disposed on the land portion 2 via the solder, the terminal of the light emitting diode easily protrudes from the land portion 2. There exists a possibility that joining strength with base film 1 may fall. On the other hand, the upper limit of the average width of the edge region R2 is 50 μm, preferably 45 μm, and more preferably 40 μm. When the average width of the edge region R2 exceeds the above upper limit, the distance that the light emitting diode moves in the land portion 2 during soldering increases, and the positional accuracy of the light emitting diode may decrease.

  It is preferable that the connection planned region R1 is substantially rectangular, and the land portion 2 is substantially rectangular in plan view. In this way, the land portion 2 can be easily formed by making the planned connection region R1 and the planar shape of the land portion 2 substantially rectangular. In addition, by positioning the planned connection region R1 and the land portion 2 in a substantially rectangular shape, positioning when the light emitting diode is disposed can be easily performed.

<Wiring section>
The wiring part 3 is connected to the land part 2. The wiring portion 3 supplies electricity to the light emitting diode and functions as a heat radiating member of the light emitting diode. A plurality of wiring portions 3 are connected to one side of the land portion 2. Each wiring part 3 is connected perpendicularly to each side of the land part 2. For the positional accuracy of the light emitting diode described above, the ratio of the total projected width of the plurality of wiring portions 3 to one side of the land portion 2 to the length of that one side is important. In the land portion 21 shown in FIG. 2, for example, on one side E1, the sum of the projection width P1 of the wiring portion 31 and the projection width P2 of the wiring portion 32 is the total projection width.

  The upper limit of the ratio of the total projected width of the plurality of wiring portions 3 to one side of the land portion 2 to the length of that one side is preferably 20%, and more preferably 15%. When the ratio exceeds the upper limit, when solder flows from the land portion 2 to the wiring portion 3, a large amount of solder flows to the wiring portion 3, so that the light emitting diode moves to the wiring portion 3 side, and Position accuracy may be reduced. On the other hand, the lower limit of the ratio is preferably 5%, more preferably 10%. If the ratio is less than the lower limit, the wiring part 3 may be too thin and may be disconnected, or the heat dissipation may be reduced.

  The wiring part 3 is connected to a corner part of the land part 2. Since the wiring part 3 is farther from the center of the land part 2 than the wiring part 3 is connected to the center of the side of the land part 2, the wiring part 3 is far from the center of the land part 2. When the solder flows, the amount of solder flowing through the wiring portion 3 is reduced. Thereby, the wiring part 3 is connected not to the center of the side of the land part 2 but to the corner part of the land part 2, so that the moving distance of the light emitting diode 6 due to the flow of solder can be further reduced.

  As shown in FIG. 1A, depending on the distance between the pair of land portions 2 on which the terminals of the pair of light emitting diodes are mounted, the wiring portions 3 are arranged and connected to the opposite sides of the pair of land portions 2. Preferably not.

<Advantages>
The printed wiring board can reduce the distance that the light emitting diode moves during soldering by setting the average width of the marginal region R2 within the above range. As a result, the error from the design position of the light emitting diode is expected to be within 0.1 mm. As a result, the positional accuracy of the light emitting diode is increased.

[Printed circuit board]
Next, a printed circuit board using the printed wiring board will be described. The printed circuit board of FIGS. 3A and 3B includes the printed wiring board and a light emitting diode 6 mounted on the plurality of lands 2 of the printed wiring board. The light emitting diode 6 is mounted on the land portion 2 by connecting the terminal 7 to the connection planned region R <b> 1 in the land portion 2 via the solder 5.

  The lower limit of the average thickness of the solder 5 is preferably 2 μm, more preferably 5 μm, and even more preferably 10 μm. On the other hand, the upper limit of the average thickness of the solder 5 is preferably 200 μm, more preferably 100 μm, and even more preferably 50 μm. If the average thickness of the solder 5 is less than the above lower limit, sufficient bonding strength between the land portion 2 and the light emitting diode 6 may not be obtained. If the average thickness of the solder 5 exceeds the upper limit, the amount of solder flowing during soldering increases, and the moving distance of the light emitting diode 6 may increase.

  Since the printed circuit board uses the printed wiring board, the positional accuracy of the light-emitting diode 6 mounted on the printed circuit board is high. As a result, it can be suitably used for an optical information transmission system.

[Method of manufacturing printed circuit board]
The printed circuit board includes, for example, (1) a step of forming a conductive pattern 4 having a plurality of land portions 2 and wiring portions 3 on the surface of the base film 1 (hereinafter also referred to as “conductive pattern forming step”),
(2) It can be obtained by a manufacturing method including a step of mounting one or a plurality of light emitting diodes 6 on the plurality of land portions 2 via solder 5 (hereinafter also referred to as “mounting step”).

<Conductive pattern formation process>
In the conductive pattern forming step, a metal foil is laminated on the surface of the base film 1, and the conductive pattern 4 is formed on the laminated metal foil. The method for laminating the metal foil on the base film 1 is not particularly limited. For example, an adhesion method in which the metal foil is bonded with an adhesive, a casting method in which a resin composition that is a material for an insulating substrate is applied on the metal foil, A laminating method or the like in which a metal foil is attached by hot pressing can be used. Further, the method for forming the conductive pattern is not particularly limited, and a conventionally known etching method, for example, can be employed. Prior to this conductive pattern formation step, the connection planned region R1 and the edge region R2 are set.

<Mounting process>
In the mounting process, the light emitting diode 6 is mounted on the land portion 2 by, for example, reflow. First, solder is laminated on the land portion 2. Next, the light emitting diode 6 is disposed in the land portion 2 so that the terminal 7 of the light emitting diode 6 is located in the connection planned region R1. And the land part 2 in which the light emitting diode 6 was arrange | positioned is heated by a reflow furnace, and the light emitting diode 6 is joined to the land part 2. FIG. The printed circuit board is manufactured as described above.

[Other Embodiments]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the configuration of the embodiment described above, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. The

  In the printed wiring board, a coverlay may be laminated on a portion excluding the land portion of the base film. This coverlay has an insulating function and an adhesive function, and is adhered to the surface of the base film and the wiring part. When the coverlay has an insulating layer and an adhesive layer, the same material as the base film can be used as the insulating layer, and the average thickness can be the same as that of the base film. Moreover, as an adhesive which comprises the adhesive layer of a coverlay, an epoxy-type adhesive agent etc. are used suitably, for example. The average thickness of the adhesive layer is not particularly limited, but is preferably 12.5 μm or more and 60 μm or less.

  In the above embodiment, a plurality of wiring portions are connected to one side of the land portion. However, the number of wiring portions connected to one side of the land portion may be one. The total number of wiring parts connected to the land part may be one.

  Moreover, in the said embodiment, although the wiring part was connected to the corner | angular part of a land part, the wiring part may be connected to the center part of the land part. However, as described above, the wiring portion is preferably connected to the corner portion of the land portion.

  In the above embodiment, the wiring portion is connected perpendicularly to the side of the land portion. However, as shown in FIG. 4, the wiring portion 33 may be connected obliquely to one side E2 of the land portion 22. Good. In this case, the projected width of the wiring portion 33 is a length P3 along the one side E2 of the connection portion between the wiring portion 33 and the one side E2 of the land portion 22.

  Further, as shown in FIG. 5, the wiring part 34 may be connected across two sides E <b> 3 and E <b> 4 adjacent to each other at the corner part of the land part 23. In this case, the projection width of the wiring portion 34 with respect to one side E3 of the land portion 23 is a length P4 along the one side E3 of the connection portion between the wiring portion 34 and one side E3 of the land portion 23. Similarly, the projection width of the wiring part 34 with respect to one side E4 of the land part 23 is a length P5 along the one side E4 of the connection part between the wiring part 34 and one side E4 of the land part 23.

  Moreover, in the said embodiment, although the shape of the connection plan area | region and the shape in planar view of a land part were made into the substantially rectangular shape, it is good also as shapes other than a substantially rectangular shape according to the shape of the terminal of the light emitting diode to mount.

  In the above embodiment, a flexible printed wiring board using a flexible base film is used. However, a rigid printed wiring board may be used using a non-flexible base film.

  The printed wiring board, printed circuit board, and printed circuit board manufacturing method of the present invention can increase the positional accuracy of the light emitting diode. Therefore, it can be suitably used for an optical information transmission system or the like.

DESCRIPTION OF SYMBOLS 1 Base film 2, 21, 22, 23 Land part 3, 31, 32, 33, 34 Wiring part 4 Conductive pattern 5 Solder 6 Light emitting diode 7 Terminal

Claims (7)

An insulating base film and a conductive pattern laminated on the surface of the base film and having a plurality of land portions and wiring portions are mounted, and one or a plurality of light emitting diodes are mounted on the plurality of land portions via solder. Printed wiring board,
The land portion is laminated in a plan view in a connection planned region of the connection terminal of the light emitting diode that is the connection target, and a marginal region continuous to the outer edge of the connection planned region,
A printed wiring board having an average width of the edge region of 10 μm or more and 50 μm or less. The connection planned area is substantially rectangular,
The printed wiring board according to claim 1, wherein the land portion is substantially rectangular in a plan view. One or more wiring parts are connected to the land part,
The printed wiring board according to claim 2, wherein a total projected width of one or a plurality of wiring portions with respect to one side of the land portion is 20% or less of a length of the one side.   The printed wiring board according to claim 2, wherein the wiring portion is connected to a corner portion of the land portion.   The printed wiring board according to any one of claims 1 to 4, wherein the base film has flexibility. The printed wiring board according to any one of claims 1 to 5,
A printed circuit board comprising: one or a plurality of light emitting diodes mounted on a plurality of land portions of the printed wiring board. An insulating base film, a conductive pattern laminated on the surface of the base film and having a plurality of land portions and wiring portions, and one or a plurality of light emitting diodes mounted on the plurality of land portions via solder A printed circuit board manufacturing method comprising:
Forming a conductive pattern having a plurality of land portions and wiring portions on the surface of the base film;
A step of mounting one or more light emitting diodes on the plurality of land portions via solder,
In the conductive pattern forming step, the land portion is laminated in a plan view in a connection planned region of a connection terminal of a light emitting diode that is a connection target and a peripheral region that is continuous with an outer edge of the connection planned region, A method for manufacturing a printed circuit board, wherein an average width of the edge region is 10 μm or more and 50 μm or less.

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