JP2016082002A - Wiring board and mounting board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board capable of achieving good thermal conductivity on the side provided with a light-emitting component.SOLUTION: The wiring board includes a metal substrate, a mounting electrode part and wiring provided on a first surface side of the metal substrate, and an insulating layer disposed between the metal substrate and both the mounting electrode part and the wiring. The insulating layer is configured so that a clearance exists between a portion of the insulating layer and other portions of the insulating layer when viewed along a surface direction of the metal substrate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wiring board on which a light emitting component is mounted and a mounting board on which the light emitting component is mounted.

  In recent years, it has been proposed to configure a light-emitting device such as a lighting device using a light-emitting component including a light-emitting element that functions as a point light source, such as a light-emitting diode. For example, in Patent Document 1, a light-emitting device is configured by preparing a wiring board on which terminals and wiring for driving a light-emitting component are formed and mounting the light-emitting component on the wiring board.

  Incidentally, the directivity of light emitted from a light emitting element such as a light emitting diode is generally higher than the directivity of light emitted from a conventional fluorescent lamp. For this reason, for example, when a light emitting diode is used in a lighting device, in order to suppress the shape and arrangement of the light emitting diode from being visually recognized by the user and reduce the straight light from the light emitting diode, in general, as a light diffusing agent. A functional lighting cover is provided to cover the light emitting diode. In addition, a reflection layer capable of reflecting light with high reflectivity is formed on the surface of the wiring board on which the light emitting component is mounted in order to increase the light use efficiency.

  For example, in Patent Document 1, a reflective layer is formed on a wiring board using a white pigment made of a powder of a ceramic material that can realize high reflectivity, such as titanium oxide, calcium oxide, and zinc oxide. Proposed. A wiring board provided with such a reflective layer includes, for example, a coating process in which a paste containing a white pigment is first applied on a board for constituting the wiring board, and then a baking process in which the paste is baked and hardened. It is formed by performing.

JP 2006-147999 A

  In recent years, instead of a rigid substrate such as a glass epoxy substrate, a wiring substrate having a flexible metal substrate, a so-called flexible substrate has been used. The flexible substrate has various advantages such as being lightweight and capable of supporting a three-dimensional shape such as a cylindrical shape or a mountain shape. A general flexible substrate has a metal substrate made of a flexible resin material such as polyethylene terephthalate, and a metal mounting electrode portion formed on the surface of the metal substrate. .

  When power is applied to the light emitting component, light is emitted from the light emitting component and heat is generated in the light emitting component. In order to operate the light emitting component with high reliability, it is necessary to appropriately dissipate heat generated in the light emitting component to the outside. On the other hand, the thermal conductivity of the flexible substrate in the surface direction is generally lower than the thermal conductivity of the conventional rigid substrate. Further, as described above, the reflective layer is provided on the side of the flexible substrate on which the light emitting component is provided. Therefore, in the flexible substrate, the heat conductivity of the heat dissipation path in which the heat generated in the light emitting component is conducted in the surface direction of the substrate and then radiated to the atmosphere through the reflective layer is low. For this reason, the heat generated in the light-emitting component is mainly conducted along the thickness direction of the flexible substrate from the side where the light-emitting component is provided to the opposite side of the flexible substrate, and then the aluminum plate attached to the flexible substrate The heat is radiated to the outside through a support member such as. In order to further improve the heat dissipation of the flexible substrate, it is required to increase the thermal conductivity in the surface direction of the flexible substrate on the side where the light emitting component is provided, thereby efficiently releasing heat to the atmosphere.

  The present invention has been made in consideration of such points, and an object of the present invention is to provide a wiring board and a mounting board that can realize good thermal conductivity on the side where the light emitting component is provided.

  The present invention is a wiring board on which a light-emitting component is mounted, and includes a metal substrate including a first surface and a second surface located on the opposite side of the first surface, and the first surface of the metal substrate. A mounting electrode portion on which the light emitting component is mounted, a wiring provided on the first surface side of the metal substrate and connected to the mounting electrode portion, and the first of the metal substrate. An insulating layer disposed between a surface and the mounting electrode portion and between the first surface of the metal substrate and the wiring, and the insulating layer extends along a surface direction of the metal substrate. The wiring board is configured such that a gap exists between a part of the insulating layer and the other part of the insulating layer when viewed from above.

  The wiring board according to the present invention is configured to mount a plurality of light-emitting components including a first light-emitting component and a second light-emitting component adjacent to the first light-emitting component. An insulating layer positioned between the mounting electrode portion to be mounted and the first surface of the metal substrate; the mounting electrode portion on which the second light emitting component is mounted; and the first of the metal substrate. The gap portion may be present between the insulating layer and the insulating layer.

  In the wiring board according to the present invention, the wiring includes a first wiring and a second wiring that extend in parallel with each other, and the insulation is located between the first wiring and the first surface of the metal substrate. The gap portion may be present between the layer and the insulating layer located between the second wiring and the first surface of the metal substrate.

  In the wiring board according to the present invention, the metal substrate may have flexibility.

  The wiring board according to the present invention further includes a reflective layer provided on the first surface side of the metal substrate, in which white pigments or bubbles are dispersed, and the reflective layer is at least partly the first of the metal substrate. You may arrange | position so that a surface may be contact | connected.

  The present invention is a mounting board on which a light emitting component is mounted, and includes the wiring board described above and the light emitting component mounted on the mounting electrode portion of the wiring board.

  According to the present invention, good thermal conductivity can be realized on the side where the light emitting component is provided.

FIG. 1 is a plan view showing a mounting board according to an embodiment of the present invention. FIG. 2 is a plan view showing a case where light emitting components, mounting electrode portions, wiring, and extraction electrode portions are removed from the mounting substrate shown in FIG. 1 for convenience. 3 is a cross-sectional view of the mounting board of FIG. 1 as viewed from the III-III direction. 4 is a cross-sectional view of the mounting substrate of FIG. 1 as viewed from the IV-IV direction. FIG. 5 is a cross-sectional view showing a light-emitting component mounted on a mounting board. FIG. 6 is a diagram showing a step of forming an insulating layer on the first surface side of the metal substrate. FIG. 7 is a diagram illustrating a process of forming a mounting electrode portion and wiring on an insulating layer. FIG. 8 is a diagram illustrating a process of forming a reflective layer on the first surface side of the metal substrate. FIG. 9 is a diagram illustrating a method of manufacturing a mounting board by mounting light emitting components. FIG. 10 is a cross-sectional view illustrating an example of a lighting device including a mounting substrate. FIG. 11 is a view showing a laminate used for manufacturing a wiring board in a modification of the embodiment of the present invention. 12 is a view showing a mounting electrode portion and wiring obtained by patterning the conductive layer of the laminate shown in FIG. 13 is a diagram showing a step of etching an insulating layer using the mounting electrode portion and the wiring shown in FIG. 12 as a mask.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual ones. Further, in this specification, the terms “substrate” and “sheet” are not distinguished from each other based only on the difference in designation. For example, the “substrate” is a concept including a member that can be called a sheet or a film. Furthermore, as used in this specification, the shape and geometric conditions and the degree thereof are specified. For example, terms such as “parallel” and “orthogonal”, length and angle values, and the like are bound to a strict meaning. Therefore, it should be interpreted including the extent to which similar functions can be expected.

  First, a mounting board 60 obtained by mounting a light emitting component 61 on a wiring board will be described with reference to FIG. As will be described later, the mounting substrate 60 including the light emitting component 61 can be combined with an illumination cover configured as a diffusion plate and a support member such as a base or a housing to constitute an illumination device. FIG. 1 is a plan view showing a case where the mounting board 60 is viewed from the side where the light emitting component 61 is mounted.

As shown in FIG. 1, the mounting substrate 60 is flexible and has a wiring substrate 40 that functions as a so-called flexible substrate and a plurality of mounting electrodes 41 mounted on the wiring substrate 40, which will be described later. And a light emitting component 61. As long as a light emitting element that can function as a point light source is provided, the configuration of the light emitting component 61 is not particularly limited. For example, a light-emitting diode can be used as the light-emitting element, and a surface-mounted component including a light-emitting diode housed in a surface-mounted package can be used as the light-emitting component 61.

  As will be described later, the mounting substrate 60 is formed by forming the insulating layer 22 and the mounting electrode portion 41 on the long metal substrate 21 supplied in a rolled state. The light-emitting component 61 is manufactured and mounted on the wiring substrate 40, and the wiring substrate 40 is cut before or after the light-emitting component 61 is mounted. In FIG. 1, the longitudinal direction of the metal substrate 21 and the wiring substrate 40 is represented by the symbol D1, and the direction orthogonal to the longitudinal direction D1 is represented by the symbol D2. The direction D2 corresponds to a direction in which the wiring board 40 is cut. The “long direction” is a direction in which the long metal substrate 21 and the wiring substrate 40 extend. In the following description, the longitudinal direction D1 may be referred to as a first direction D1, and the direction D2 orthogonal to the first direction D1 may be referred to as a second direction D2. In the following description, the surface of the metal substrate 21 on the side where the light emitting component 61 is provided is also referred to as a first surface 21a, and the surface on the opposite side of the first surface 21a is also referred to as a second surface 21b. is there.

  In FIG. 1, the pair of first side portions of the metal substrate 21 extending along the first direction D1 between the first surface 21a and the second surface 21b is represented by reference numeral 21c. A pair of second side portions of the metal substrate 21 extending along the second direction D2 orthogonal to the first direction D1 is represented by reference numeral 21d.

Referring to the wiring board and then 1, 3, 4, a detailed description of the construction of the wiring board 40. 3 is a cross-sectional view of the mounting substrate 60 of FIG. 1 as viewed from the III-III direction, and FIG. 4 is a cross-sectional view of the mounting substrate of FIG. 1 as viewed from the IV-IV direction.

  As shown in FIGS. 3 and 4, the wiring substrate 40 is provided on the metal substrate 21 having flexibility and the first surface 21 a side of the metal substrate 21, and the mounting electrode portion on which the light emitting component 61 is mounted. 41, wiring 42 provided on the first surface 21a of the metal substrate 21 and connected to the mounting electrode portion 41, between the first surface 21a of the metal substrate 21 and the mounting electrode portion 41, and the metal substrate 21. And an insulating layer 22 disposed between the first surface 21 a and the wiring 42. The mounting electrode portion 41 is a portion for mounting the light emitting component 61 and is also referred to as a pad or a land.

  As shown in FIG. 1, the wiring substrate 40 includes an extraction electrode portion 43 provided on the first surface 21 a side of the metal substrate 21 so as to be electrically connected to the light emitting component 61 via the wiring 42. Also good. In this case, although not shown, the insulating layer 22 is also provided between the first surface 21 a of the metal substrate 21 and the extraction electrode portion 43.

  In the present embodiment, “flexibility” refers to the degree that a fold does not occur in the wiring board 40 when the wiring board 40 is wound into a roll shape having a diameter of 30 cm in an environment of room temperature, for example, 25 ° C. Means flexibility. A “fold” is a deformation that appears on the wiring board 40 in a direction that intersects the winding direction of the wiring board 40, and even if the wiring board 40 is wound in the opposite direction so as to restore the deformation to the original state. Means deformation that does not return.

(Metal substrate)
The metal substrate 21 is a flexible substrate made of a metal material. The metal material constituting the metal substrate 21 and the thickness of the metal substrate 21 are appropriately determined according to characteristics such as flexibility and strength required for the wiring substrate 40. For example, the metal substrate 21 can include at least one of copper, aluminum, silver, or iron. In order to further improve the heat dissipation, an aluminum foil that has been anodized may be used as the metal substrate 21. The thickness of the metal substrate 21 is in the range of 10 μm to 200 μm, for example.

(Mounting electrode, wiring, and extraction electrode)
As a material constituting the mounting electrode portion 41, the wiring 42, and the extraction electrode portion 43, a conductive material is used, and for example, a metal material such as copper or silver is used. In consideration of enhancing the reflection characteristics of the wiring board 40, silver is preferably used.

  The materials constituting the mounting electrode portion 41, the wiring 42, and the extraction electrode portion 43 may be the same or different. For example, the mounting electrode portion 41, the wiring 42, and the extraction electrode portion 43 may be formed simultaneously and continuously by patterning the same conductive layer, as will be described later. As long as the wiring substrate 40 and the mounting substrate 60 have flexibility in a desired direction, the dimensions such as the thickness and width of the mounting electrode portion 41, the wiring 42, and the extraction electrode portion 43 are not particularly limited.

  As shown in FIG. 1, the wiring 42 is configured to extend linearly along a predetermined direction. In the example shown in FIG. 1, the wiring 42 includes a linear portion 42a extending linearly along the first direction D1 and the second direction D2. Here, “linear” means a form in which the dimension in the length direction is relatively larger than the dimension in the width direction, for example, 10 times or more.

  As shown in FIG. 1, in the present embodiment, the light emitting components 61 are arranged on the wiring board 40 so that the plurality of light emitting components 61 are arranged along the first direction D1 in which the first side portion 21c of the metal substrate 21 extends. The mounting electrode portions 41 that are mounted and on which the plurality of light emitting components 61 arranged along the first direction D1 are mounted are electrically connected in series via the wiring. Further, the wiring 42 includes a portion that extends intermittently along the first direction D1 so as to electrically connect the mounting electrode portions 41 on which the two adjacent light emitting components 61 are mounted. Even when the wiring 42 is intermittently extended in this way, when the line virtually extending one line segment of the wiring 42 overlaps the line segment of the other wiring 42, such a wiring 42 is also used. It may be referred to as a linear portion 42a.

(Insulating layer)
The insulating layer 22 is a layer provided to prevent the metal substrate 21 from being electrically connected to the mounting electrode portion 41, the wiring 42, and the extraction electrode portion 43. As a material constituting the insulating layer 22, an insulating resin material can be used. Examples of the resin material include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, epoxy resins, and polyimide resins. The insulating layer 22 has a thickness in the range of 1 μm to 200 μm, for example.

  In a conventional flexible substrate, the mounting electrode portion and wiring are generally formed on an insulating resin substrate, and on the surface of the resin substrate on which the mounting electrode portion and wiring are not formed. The metal substrate which functions as a heat sink is attached. In this case, the resin substrate functions as an insulating layer for preventing the metal substrate from being electrically connected to the mounting electrode portion and the wiring. On the other hand, the thermal conductivity of the resin substrate is lower than that of the metal substrate. For this reason, in the conventional flexible substrate, the heat generated in the light emitting component is transmitted to the metal substrate, and even if the heat is diffused in the surface direction in the metal substrate, the heat is not in contact with the resin substrate in the metal substrate. Is released into the atmosphere from the surface. That is, the heat dissipation path from the surface of the metal substrate that contacts the resin substrate to the atmosphere via the resin substrate is not effectively utilized. This is because heat conduction is hindered by the resin substrate.

  On the other hand, from the viewpoint of preventing conduction between the metal substrate and the mounting electrode portion 41 and the wiring 42, an insulating layer such as a resin substrate does not necessarily have to exist over the entire area of the wiring substrate 40. . That is, it is only necessary that an insulating layer exists between the metal substrate and the mounting electrode portion 41 or the wiring 42 at least at a position where the mounting electrode portion 41 or the wiring 42 is provided. Against this background, in the present embodiment, as shown in FIG. 1 and FIG. 4, when viewed along the surface direction of the metal substrate 21, a part of the insulating layer 22 and other parts of the insulating layer 22. It is proposed that the insulating layer 22 be configured so that a gap exists between the portions. By providing such a gap 23, the ratio of the area where the insulating layer 22 is provided in the first surface 21 a of the metal substrate 21 can be reduced. As a result, it is possible to suppress the heat dissipation from the first surface 21a side of the metal substrate 21 from being hindered by the insulating layer 22, thereby releasing heat from the first surface 21a of the metal substrate 21 to the atmosphere. It is possible to more effectively utilize the heat dissipation path. In the following description, the ratio of the area of the first surface 21a of the metal substrate 21 where the insulating layer 22 is provided is also referred to as “the area ratio of the insulating layer 22”. The “plane direction” is a direction orthogonal to the normal direction of the metal substrate 21. The “gap portion 23” is a region where the insulating layer 22 is not present in the region on the first surface 21a of the metal substrate 21.

  Hereinafter, a specific shape of the insulating layer 22 will be described mainly with reference to FIGS. 1 and 2. FIG. 2 is a plan view showing a case where the light emitting component, the mounting electrode portion, the wiring, and the extraction electrode portion are removed from the mounting substrate shown in FIG. 1 for convenience.

  As shown in FIG. 1, the insulating layer 22 is formed in a pattern corresponding to the pattern of the mounting electrode portion 41 and the wiring 42. Specifically, as shown in FIGS. 1 and 2, the insulating layer 22 has a shape corresponding to the mounting electrode portion 41, and is disposed between the metal substrate 21 and the mounting electrode portion 41. The first portion 22a has a shape corresponding to the wiring 42, the second portion 22b disposed between the metal substrate 21 and the wiring 42, and the shape corresponding to the extraction electrode portion 43. And a third portion 22c disposed between the electrode portion 43 and the extraction electrode portion 43. For example, the first portion 22a has a shape similar to the mounting electrode portion 41 or the light emitting component 61, and specifically has a rectangular shape. The second portion 22b extends, for example, in the same manner as the linear portion 42a of the wiring 42.

  Next, the shape of the gap 23 formed between a part of the insulating layer 22 and the other part of the insulating layer 22 will be described. For example, the gap portion 23 is an insulating layer located between the first light emitting component 61, for example, the mounting electrode portion 41 on which the light emitting component 61 located at the center in FIG. 4 is mounted and the first surface 21 a of the metal substrate 21. 22, the second light emitting component 61 adjacent to the first light emitting component 61, for example, the mounting electrode portion 41 on which the light emitting component 61 located on the left side in FIG. 4 is mounted, and the first surface 21 a of the metal substrate 21. It exists between the insulating layer 22 located between them. In the example shown in FIG. 4, two wirings 42 are provided so as to cross between the first light-emitting component 61 and the second bonding layer 62. The gap 23 between the two light emitting components 61 is a gap 23 between the first light emitting component 61 and the wiring 42, a gap 23 between the two wires 42, and the wiring 42 and the second It is divided into a gap 23 between the light emitting component 61.

  FIG. 4 shows an example in which the gap 23 exists between the insulating layers 22 corresponding to the two light emitting components 61 adjacent in the second direction D2, but the present invention is not limited to this. There may be a gap 23 between the insulating layers 22 corresponding to the two light emitting components 61 adjacent in the first direction D1.

  The gap 23 may exist between a pair of wirings 42 extending in parallel to each other. For example, as shown in FIG. 4, the gap portion 23 is an insulating layer located between the first wiring 42 extending in the first direction D <b> 1 in the vicinity of the first light emitting component 61 and the first surface 21 a of the metal substrate 21. 22 and an insulating layer 22 positioned between the second wiring 42 extending in the first direction D1 in parallel with the first wiring 42 in the vicinity of the second light emitting component 61 and the first surface 21a of the metal substrate 21. , May exist between. In this case, the gap 23 may extend linearly like the wiring 42. That is, the gap 23 may be a long and narrow gap, that is, a slit.

(Bonding layer)
3 and 4, reference numeral 62 denotes a light emitting component 61 and a mounting electrode portion 41 for joining the light emitting component 61 to the mounting electrode portion 41 and electrically connecting the light emitting component 61 to the mounting electrode portion 41. It represents a bonding layer interposed between the two. Examples of the material constituting the bonding layer 62 include cream solder applied on the mounting electrode portion 41 in a reflow process. Cream solder includes a binder material such as flux, and metal powder that is dispersed in the binder material and melts during the reflow process. 3 and 4 show an example in which the bonding layer 62 is clearly interposed between the light emitting component 61 and the mounting electrode portion 41, but the present invention is not limited to this. The shape and arrangement of the bonding layer 62 are not particularly limited as long as the light emitting component 61 can be coupled to the mounting electrode portion 41 to electrically connect the light emitting component 61 to the mounting electrode portion 41.

  By the way, in the reflow process, at least the mounting electrode portion 41 and the peripheral portion of the wiring board 40 are heated to a temperature equal to or higher than the melting point of the solder contained in the bonding layer 62. In the following description, the maximum temperature reached by the heated wiring board 40 is also referred to as the reached temperature. In wiring board 40 according to the present embodiment, it is considered that deformation of insulating layer 22 and oligomer precipitation tend to occur when the ultimate temperature increases. Therefore, it is preferable to set the temperature at the time of performing the reflow process as low as possible so that the temperature reached by the wiring board 40 is lowered.

  In consideration of such points, the present inventors propose to use a low melting point solder that melts at a temperature of 180 ° C. or lower, more preferably 150 ° C. or lower, as the solder contained in the bonding layer 62. . In this case, the ultimate temperature of the wiring board 40 can be set to 180 ° C. or lower, more preferably 150 ° C. or lower, and this can suppress the deterioration of the characteristics of the insulating layer 22.

  As will be described later, a reflective layer 44 may be provided on the first surface 21 a side of the metal substrate 21. The use of the low melting point solder is also effective in suppressing deterioration of the characteristics of the reflective layer 44 such as deformation or discoloration of the reflective layer 44.

  As long as melting is performed at a temperature of 180 ° C. or lower, the low melting point solder included in the bonding layer 62 is not particularly limited. For example, solder containing 42 wt% to 43 wt% tin and 57 wt% to 58 wt% bismuth can be used as the low melting point solder. In addition, a solder containing tin, bismuth, and silver can be used.

(Light-emitting parts)
Next, the light emitting component 61 will be described with reference to FIG. As shown in FIG. 5, the light emitting component 61 includes a light emitting element 66 and a terminal 67 that is electrically connected to the light emitting element 66 and at least partially exposed to the outside. The terminal 67 is connected via a bonding wire 67a. The terminal 67 is generally made of a metal material such as copper or silver. Heat generated in the light emitting component 61 is conducted to the mounting electrode portion 41 via the terminal 67.

  As shown in FIG. 5, a phosphor 68 for converting the wavelength of light emitted from the light emitting element 66 may be provided around the light emitting element 66. As shown in FIG. 5, a reflector 69 that reflects light may be disposed around the phosphor 68. Thereby, the light emitted from the light emitting element 66 can be extracted with high efficiency. A transparent resin 65 may be provided on the phosphor 68.

  Next, the operation and effect of the present embodiment having such a configuration will be described. Here, a method of manufacturing the above-described mounting substrate 60 by manufacturing the above-described wiring substrate 40 using the long metal substrate 21 and mounting the light emitting component 61 on the wiring substrate 40 will be described.

(Method for manufacturing a wiring board)
First, a long metal substrate 21 is prepared. Next, as shown in FIG. 6, on the first surface 21 a of the metal substrate 21, a first portion 22 a having a shape corresponding to the mounting electrode portion 41 and a second portion 22 b having a shape corresponding to the wiring 42. Are formed. For example, first, a paste containing a material constituting the insulating layer 22 is prepared, and then the paste is applied to the first pattern of the metal substrate 21 in a pattern corresponding to the mounting electrode portion 41 and the wiring 42 using a screen printing method or the like. It is applied on the surface 21a. As a result, the insulating layer 22 can be formed on the first surface 21a of the metal substrate 21 so that the gap 23 described above exists at least partially. Although not shown, at this time, the third portion 22 c of the insulating layer 22 having a shape corresponding to the extraction electrode portion 43 may be formed at the same time.

  Next, as shown in FIG. 7, the mounting electrode portion 41 and the wiring 42 are formed on the insulating layer 22. A method for forming the mounting electrode portion 41 and the wiring 42 is not particularly limited, and a known method is appropriately used. For example, first, a conductive layer containing a metal material for constituting the mounting electrode portion 41 and the wiring 42 is provided on the first surface 21 a side of the metal substrate 21, and then corresponds to the mounting electrode portion 41 and the wiring 42. A photosensitive layer having a pattern is provided on the conductive layer. Thereafter, the mounting electrode portion 41 and the wiring 42 can be formed on the insulating layer 22 by etching the conductive layer using the photosensitive layer as a mask. Further, the mounting electrode portion 41 and the wiring 42 may be formed on the insulating layer 22 by using a laser ablation method in which the conductive layer 22 is irradiated with a laser in a pattern corresponding to the mounting electrode portion 41 and the wiring 42. In addition, the mounting electrode portion 41 and the wiring 42 may be formed on the insulating layer 22 by printing a conductive paste on the insulating layer 22. In this manner, a long wiring board 40 can be manufactured. The obtained long wiring board 40 is wound up into a roll shape.

  As shown in FIG. 8, after forming the mounting electrode portion 41 and the wiring 42, a reflective layer 44 in which white pigments or bubbles are dispersed may be formed on the first surface 21 a side of the metal substrate 21. As will be described later, the reflective layer 44 is a layer provided on the first surface 21a side of the metal substrate 21 in order to reflect the light reflected by the diffuser plate or the like and returned to the wiring substrate 40 and to go outward again. It is. The case where the wiring board 40 includes the reflective layer 44 will also be described with reference to FIG.

  Preferably, as shown in FIG. 8, the reflective layer 44 is disposed so as to be at least partially in direct contact with the first surface 21 a of the metal substrate 21. Thereby, heat can be efficiently conducted from the first surface 21a of the metal substrate 21 to the reflective layer 44, and thus heat can be efficiently released from the first surface 21a side of the metal substrate 21 to the atmosphere. Can do.

  The configuration of the reflective layer 44 is not particularly limited as long as it can reflect light and thereby increase the light use efficiency in the lighting device. For example, the reflective layer 44 can be configured as a layer in which white pigments having reflectivity, such as white ceramic material or metal powder, or bubbles are dispersed. When a white pigment is used, the reflective layer 44 first provides a paste containing a reflective white pigment such as a white ceramic material or metal powder on the first surface 21a side of the metal substrate 21, and then baked the paste. It is formed by hardening. The method for providing the paste on the first surface 21a of the metal substrate 21 or the wiring 42 is not particularly limited, and a screen printing method or the like can be used as appropriate. As the white pigment, white ceramic materials such as titanium oxide, calcium oxide, aluminum oxide, and zinc oxide can be used. In addition, various materials that can exhibit a white color, such as a white dye, can be used as the white pigment contained in the reflective layer 44.

  Preferably, the reflective layer 44 is configured such that the total light reflectance in the light wavelength range of 380 nm to 780 nm is in the range of 60% to 99%. Here, the “total light reflectance” is the sum of regular reflectance and diffuse reflectance. The total light reflectance can be obtained in accordance with the total light reflectance measurement method of JIS K7375. Specifically, the total light reflectivity is 10 nm at a light wavelength of 380 nm to 780 nm using a spectrophotometer and an integrating sphere test stand when the light is incident on the reflection layer 44 at an angle. It can be determined by measuring at intervals and calculating their average value. The total light reflectance is obtained as a relative value with the reflectance of a standard white plate containing barium sulfate as 100%.

  Preferably, the thickness of the reflective layer 44 is set so as to realize the above-described value of total light reflectance and not to inhibit heat radiation from the first surface 21a of the metal substrate 21 to the atmosphere. For example, the thickness of the reflective layer 44 is in the range of 1 μm to 200 μm.

  As shown in FIG. 8, an adhesive layer 24 may be provided on the second surface 21 b side of the metal substrate 21. The adhesive layer 24 is for attaching the wiring board 40 and the mounting board 60 to a support member 81 described later. By providing the adhesive layer 24 in advance, the attachment process of the support member 81 can be facilitated. As shown in FIG. 8, a release sheet 25 for protecting the adhesive surface of the adhesive layer 24 may be provided on the adhesive layer 24. As a material constituting the adhesive layer 24, for example, acrylic, epoxy, urethane or the like can be used.

(Manufacturing method of mounting substrate)
Next, a method for manufacturing the mounting board 60 using the mounting board manufacturing apparatus 50 will be described with reference to FIG.

  First, as shown in FIG. 9, an unwinding portion 51 that holds a long wiring substrate 40 wound in a roll shape is prepared. Next, the wiring board 40 is unwound from the unwinding portion 51. Next, as shown in FIG. 9, a bonding layer 62 is provided on the mounting electrode portion 41 of the wiring board 40. For example, cream solder for forming the bonding layer 62 is applied onto the mounting electrode part 41 using the application part 52. Thereafter, using the mounting portion 53, a mounting step of mounting the light emitting component 61 on the mounting electrode portion 41 provided with the bonding layer 62, a so-called reflow step is performed. Specifically, first, the light emitting component 61 is placed on the mounting electrode portion 41 provided with the bonding layer 62, and then the mounting electrode portion on which at least the light emitting component 61 of the wiring board 40 is placed. The portion 41 is heated to melt the bonding layer 62. As a result, the light emitting component 61 is joined to the mounting electrode portion 41. Next, the wiring board 40 on which the light emitting component 61 is mounted is cut in the second direction D2 orthogonal to the first direction D1 using the cutting unit 54. Thereby, the mounting substrate 60 on which the light emitting component 61 is mounted can be obtained.

(Manufacturing method of lighting device)
Thereafter, as shown in FIG. 10, a support member 81 may be attached to the mounting substrate 60 on which the light emitting component 61 is mounted via the adhesive layer 24. Examples of the support member 81 include a metal base, a housing, and a metal plate that functions as a heat sink. In the following description, the mounting substrate 60 further including the support member 81 attached to the wiring substrate 40 on the second surface 21b side of the metal substrate 21 may be referred to as a lighting device 80. By attaching such a support member 81, it is possible to more efficiently dissipate heat from the second surface 21b side of the metal substrate 21 to the atmosphere.

  In addition, according to the present embodiment, as described above, the insulating layer 22 provided between the first surface 21a of the metal substrate 21 and the mounting electrode portion 41 or the wiring 42 is formed by a part of the insulating layer 22 and the insulating layer. The gap portion 23 exists between the other portions of 22. For this reason, the area ratio of the insulating layer 22 provided in the 1st surface 21a side of the metal substrate 21 is small compared with the conventional flexible substrate. Thereby, it is possible to suppress the heat dissipation from the first surface 21 a side of the metal substrate 21 to the atmosphere from being hindered by the insulating layer 22. That is, the thermal conductivity of the wiring substrate 40 in the heat dissipation path from the first surface 21a side of the metal substrate 21 to the atmosphere can be lowered. For this reason, the heat generated in the light emitting component 61, transmitted to the metal substrate 21 through the mounting electrode portion 41 and the first portion 22 a of the insulating layer 22, and diffused in the surface direction in the metal substrate 21 is transferred to the metal substrate 21. It is possible to efficiently dissipate heat from the first surface 21a side to the atmosphere. As described above, according to the present embodiment, it is possible to increase the thermal conductivity of the wiring board 40 as a whole, and as a result, the temperature of the mounting electrode portion 41 and its peripheral portion is locally increased. This can be suppressed. Therefore, the lifetime and reliability of the light emitting component 41 can be improved.

  Further, according to the present embodiment, by reducing the area ratio of the insulating layer 22, the magnitude of the force resisting bending caused by the presence of the insulating layer 22 is reduced when the wiring board 40 is bent. can do. As a result, the ease of winding the wiring board 40 can be improved. Further, when the support member 81 to which the wiring board 40 and the mounting board 60 are attached has a curved shape, it is easy to deform the wiring board 40 and the mounting board 60 so as to follow such a curved shape.

  Moreover, according to this Embodiment, the usage-amount of the material which comprises the insulating layer 22 can be reduced by reducing the area ratio of the insulating layer 22. FIG. Thereby, the cost required for manufacturing the wiring board 40 and the mounting board 60 can be reduced.

  Further, according to the present embodiment, as described above, the cream solder applied onto the mounting electrode portion 41 includes a solder containing a low melting point solder that melts at a temperature of 180 ° C. or lower. For this reason, the ultimate temperature which the wiring board 40 reaches | attains in the case of a mounting process can be 180 degrees C or less. As a result, it is possible to suppress deterioration of the characteristics of the insulating layer 22 and the reflective layer 44 due to heating during the mounting process. In addition, a resin material having relatively low heat resistance can be used as the resin material included in the insulating layer 22 and the reflective layer 44.

  As illustrated in FIG. 10, the lighting device 80 may further include a diffusion plate 82 provided with a space between the mounting substrate 60 and the mounting substrate 60 on the side where the light emitting component 61 is mounted. Good. As the diffusing plate 82, an illumination cover or the like that functions as a light diffusing agent can be used. In this case, as described below, an effect of increasing the light use efficiency in the illumination device 80 is also expected.

  In FIG. 10, an arrow with a symbol L <b> 1 represents light emitted from the light emitting component 61. Of the light L 1 emitted from the light emitting component 61, most of the light incident on the diffusion plate 82 substantially along the normal direction of the diffusion plate 82 passes through the diffusion plate 82 and reaches the user side. On the other hand, of the light L1 emitted from the light emitting component 61, the light incident on the diffusion plate 82 along the direction inclined from the normal direction of the diffusion plate 82 is reflected by the diffusion plate 82 and returns to the mounting substrate 60. There is. As shown by an arrow L21 in FIG. 10, most of such return light is reflected by the reflection layer 44, travels again to the diffusion plate 82, and passes through the diffusion plate 82 to reach the user side. Further, as shown by an arrow L22 in FIG. 10, the other return light is reflected by the metal substrate 21 after being transmitted through the reflective layer 44, is directed again toward the diffusion plate 82, and is transmitted through the diffusion plate 82 to the user side. It reaches. As described above, according to the present embodiment, the light transmitted through the reflective layer 44 can be reflected by the metal substrate 21 even when the reflectance of the light in the reflective layer 44 is not sufficiently high. The light use efficiency in the device 80 can be sufficiently increased.

  Note that various modifications can be made to the above-described embodiment. Hereinafter, modified examples will be described with reference to the drawings as necessary. In the following description and the drawings used in the following description, the same reference numerals as those used for the corresponding parts in the above embodiment are used for the parts that can be configured in the same manner as in the above embodiment. A duplicate description is omitted. In addition, when it is clear that the operational effects obtained in the above-described embodiment can be obtained in the modified example, the description thereof may be omitted.

(Modification of manufacturing method of wiring board)
In the present embodiment described above, the insulating layer 22 is formed by applying a paste containing a resin material on the first surface 21 a of the metal substrate 21 in a pattern corresponding to the mounting electrode portion 41 and the wiring 42. An example was given. However, first, by providing the insulating layer 22 on the first surface 21a side of the metal substrate 21, and then patterning the insulating layer 22 using an etching method or the like, a pattern corresponding to the mounting electrode portion 41 and the wiring 42 is obtained. The insulating layer 22 may be formed.

  In this case, for example, as shown in FIG. 11, first, the metal substrate 21, the insulating layer 22 provided on the first surface 21a of the metal substrate 21, and the conductive layer 26 provided on the insulating layer 22 are provided. The laminated body 20 containing is prepared. The conductive layer 26 is a layer containing a metal material that constitutes the mounting electrode portion 41 and the wiring 42.

  Next, the conductive layer 26 is patterned to form the mounting electrode portion 41 and the wiring 42 on the insulating layer 22 as shown in FIG. At this time, the extraction electrode portion 43 may be formed from the conductive layer 26 at the same time.

  As a method of patterning the conductive layer 26, a method of etching the conductive layer 26 using a photosensitive layer provided on the conductive layer 26 in a pattern corresponding to the mounting electrode portion 41 and the wiring 42, or a mounting electrode portion 41 is used. Alternatively, a known method such as a laser ablation method in which the conductive layer 26 is irradiated with a laser in a pattern corresponding to the wiring 42 can be appropriately used.

  Thereafter, the insulating layer 22 is etched using the mounting electrode portion 41 and the wiring 42 as a mask. As a result, as shown in FIG. 13, the insulating layer 22 having substantially the same pattern as the mounting electrode portion 41 and the wiring 42 is formed between the mounting electrode portion 41 and the wiring 42 and the first surface 21 a of the metal substrate 21. Can be formed.

  According to this modification, the pattern of the mounting electrode portion 41 and the wiring 42 and the pattern of the insulating layer 22 can be matched with high accuracy. For this reason, the area of the insulating layer 22 required to prevent the mounting electrode portion 41 and the wiring 42 from conducting to the metal substrate 21 can be minimized. Thereby, it is possible to further suppress the heat dissipation from the first surface 21 a side of the metal substrate 21 to the atmosphere by the insulating layer 22. Thereby, the thermal conductivity of the wiring board 40 as a whole can be further increased.

(Metal substrate modification)
In the above-described embodiment, an example in which the metal substrate 21 has a thickness small enough to be flexible has been shown. However, the present invention is not limited to this, and the metal substrate 21 may have a thickness that does not have flexibility. That is, the wiring board 40 may be configured as a so-called rigid board. Even in this case, the thermal conductivity of the entire wiring board 40 can be improved by forming the gap 23 in the insulating layer 22.

(Other variations)
In the above-described embodiment, low melting point solder that melts at a temperature of 180 ° C. or lower is used as the solder included in the bonding layer 62. As a result, the ultimate temperature of the wiring board 40 in the mounting process is 180. An example of lowering the temperature was shown. However, the present invention is not limited to this, and a general lead-free solder having a melting point of about 260 ° C. may be used as the solder contained in the bonding layer 62.

  In the above-described embodiment, the example in which the light emitting component 61 is mounted on the long wiring board 40 has been described. However, the present invention is not limited to this, and the light emitting component 61 may be mounted on the single-layer wiring board 40 after the wiring board 40 is cut.

  In the above-described embodiment, the example in which the support member 81 is attached to the wiring board 40 after the light emitting component 61 is mounted, that is, the mounting board 60 is shown. There is no. For example, the support member 81 may be attached to the wiring substrate 40 before the light emitting component 61 is mounted, and then the light emitting component 61 may be mounted on the mounting electrode portion 41 of the wiring substrate 40.

  In addition, although some modified examples with respect to the above-described embodiment have been described, naturally, a plurality of modified examples can be applied in combination as appropriate.

DESCRIPTION OF SYMBOLS 21 Metal substrate 22 Insulating layer 23 Gap part 24 Adhesive layer 26 Conductive layer 40 Wiring board 41 Mounting electrode part 42 Wiring 43 Extraction electrode part 44 Reflective layer 60 Mounting board 61 Light emitting component 62 Joining layer 80 Illumination device

Claims (6)

A wiring board on which light emitting components are mounted,
A metal substrate including a first surface and a second surface located on the opposite side of the first surface;
A mounting electrode portion provided on the first surface side of the metal substrate and on which the light emitting component is mounted;
Wiring provided on the first surface side of the metal substrate and connected to the mounting electrode portion;
An insulating layer disposed between the first surface of the metal substrate and the mounting electrode unit and between the first surface of the metal substrate and the wiring;
The wiring board, wherein the insulating layer is configured such that a gap exists between a part of the insulating layer and another part of the insulating layer when viewed along the surface direction of the metal substrate. The wiring board is configured to mount a plurality of light emitting components including a first light emitting component and a second light emitting component adjacent to the first light emitting component,
An insulating layer positioned between the mounting electrode portion on which the first light emitting component is mounted and the first surface of the metal substrate; and the mounting electrode portion on which the second light emitting component is mounted; The wiring board according to claim 1, wherein the gap portion exists between the insulating layer positioned between the first surface of the metal substrate and the insulating layer. The wiring includes a first wiring and a second wiring extending in parallel with each other,
Between the insulating layer positioned between the first wiring and the first surface of the metal substrate, and the insulating layer positioned between the second wiring and the first surface of the metal substrate. The wiring board according to claim 1, wherein the gap is present.   The wiring board according to claim 1, wherein the metal board has flexibility. A reflection layer provided on the first surface side of the metal substrate, in which white pigments or bubbles are dispersed;
The wiring board according to claim 1, wherein the reflective layer is disposed so as to be at least partially in contact with the first surface of the metal substrate. A mounting board on which light emitting components are mounted,
The wiring board according to any one of claims 1 to 5,
And a light emitting component mounted on the mounting electrode portion of the wiring board.

Images