JP6634668B2 - Manufacturing method of mounting board and mounting board - Google Patents

Description

  The present invention relates to a method for manufacturing a mounting board on which a light emitting component is mounted, and a mounting board.

  In recent years, it has been proposed to configure a light emitting device such as a lighting device using a light emitting component having a light emitting element functioning 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 wirings 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. Therefore, 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 a user, and to reduce straight traveling light from the light emitting diode, the light emitting diode is generally used as a light diffusing agent. A functional lighting cover is provided to cover the light emitting diode. Further, on the surface of the wiring board on which the light emitting components are mounted, a reflection layer capable of reflecting light at a high reflectance is formed in order to increase the light use efficiency.

  For example, Patent Literature 1 proposes forming a reflective layer on a wiring board using a white pigment that can realize high reflectance, such as titanium oxide, calcium oxide, and zinc oxide. The wiring board provided with such a reflective layer, for example, first performs a coating step of applying a paste containing a white pigment on a substrate for forming a wiring board, and then a firing step of baking and solidifying the paste It is formed by performing.

JP 2006-147999 A

  In recent years, as a wiring substrate, a substrate provided with a flexible resin substrate instead of a rigid substrate such as a glass epoxy substrate, that is, a so-called flexible substrate tends to be used. The flexible substrate has various advantages such as being lightweight and being able to cope with a three-dimensional shape such as a cylindrical shape or a mountain shape. A general flexible substrate has a resin substrate made of a resin material having flexibility such as polyethylene terephthalate, and a metal mounting electrode portion formed on the surface of the resin substrate. .

  In a flexible substrate, in order to ensure flexibility, the thickness of the above-mentioned reflective layer and the amount of a white pigment to be added are limited. In this case, it is difficult to make the reflectivity of the light in the reflective layer close to 100%, so that the light incident on the flexible substrate passes through the reflective layer at a certain ratio and reaches the resin substrate of the flexible substrate. Will do. For this reason, in order to increase the light use efficiency in the lighting device, not only the reflective layer but also the resin substrate needs to have a characteristic of appropriately reflecting light to some extent.

  Incidentally, the thickness of the flexible substrate is smaller than the thickness of the conventional rigid substrate in order to ensure flexibility. For this reason, when the flexible substrate is heated to mount the light emitting component using a reflow method or the like, oligomers contained in the resin substrate may be deposited on the surface of the resin substrate. In this case, when the light incident on the flexible substrate reaches the oligomer precipitated on the surface of the resin substrate, the light is irregularly reflected by the oligomer, and thus the light use efficiency may be reduced. It is considered that such oligomer precipitation is more likely to occur as the heating temperature is higher.

  In addition, heating the flexible substrate to a high temperature to mount the light-emitting components causes discoloration such as yellowing of the reflective layer containing a white pigment or the like, thereby reducing the whiteness of the reflective layer. Can also occur. A decrease in the whiteness of the reflective layer leads to a decrease in the reflectivity of the reflective layer and, consequently, a reduction in the light use efficiency of the lighting device. It is also conceivable that the light reflected by the reflective layer has an inappropriate color.

  The present invention has been made in view of such a point, and it is an object of the present invention to provide a method of manufacturing a mounting board, which can suppress a decrease in reflectance of a wiring board when mounting a light emitting component. With the goal.

  The present invention is a method for manufacturing a mounting board on which a light emitting component is mounted, and prepares a wiring board including a resin substrate having flexibility and a mounting electrode portion provided on the resin substrate. And a mounting step of mounting a light emitting component on the mounting electrode portion of the wiring board, wherein the wiring board includes a white pigment or bubbles for reflecting light incident on the wiring board. The mounting step includes a step of providing a bonding layer on the mounting electrode section, a step of mounting the light emitting component on the mounting electrode section provided with the bonding layer, and a step of mounting the wiring board. Heating to melt the bonding layer, wherein the bonding layer includes a low melting point solder that melts at a temperature of 180 ° C. or less.

  In the method for manufacturing a mounting substrate according to the present invention, the resin substrate includes a polyester resin, an epoxy resin, or a polyimide resin, and the thickness of the resin substrate is in a range of 10 μm to 300 μm, more preferably in a range of 10 μm to 200 μm. May be inside.

  In the method for manufacturing a mounting board according to the present invention, in the wiring board, an adhesive layer is interposed between the mounting electrode portion and the resin substrate, and the adhesive layer is at least partially provided on the resin substrate. May extend to a region that does not overlap with the mounting electrode portion when viewed along the normal direction.

  In the method for manufacturing a mounting board according to the present invention, the wiring board is provided in a region not overlapping with the mounting electrode portion and the light emitting component when viewed along a normal direction of the resin substrate, and the white pigment is provided. It may include a dispersed reflective layer.

  In the method for manufacturing a mounting board according to the present invention, a white pigment or bubbles may be dispersed in the resin substrate of the wiring board.

  The present invention is a mounting board on which a light emitting component is mounted, a resin board having flexibility, and a mounting electrode portion provided on the resin board, a wiring board including: A light-emitting component mounted on the mounting electrode portion, wherein the wiring board contains a white pigment or bubbles for reflecting light incident on the wiring board, and the mounting of the wiring board is performed. A bonding layer is interposed between the electrode unit for use and the light emitting component, and the bonding layer is a mounting board including a low melting point solder that melts at a temperature of 180 ° C. or less.

  In the mounting board according to the present invention, the resin substrate includes a polyester resin, an epoxy resin, or a polyimide resin, and the thickness of the resin substrate is in a range of 10 μm to 300 μm, more preferably, in a range of 10 μm to 200 μm. You may.

  In the wiring board of the mounting board according to the present invention, an adhesive layer is interposed between the mounting electrode portion and the resin substrate, and the adhesive layer is at least partially provided in a direction normal to the resin substrate. May extend to a region that does not overlap with the mounting electrode portion when viewed along.

  In the mounting board according to the present invention, the wiring board is provided in a region not overlapping with the mounting electrode portion and the light emitting component when viewed along a normal direction of the resin substrate, and the white pigment is dispersed. A reflective layer may be included.

  In the mounting board according to the present invention, a white pigment or air bubbles may be dispersed in the resin substrate of the wiring board.

  ADVANTAGE OF THE INVENTION According to this invention, when mounting a light emitting component, it can suppress that the reflectance of a wiring board falls.

FIG. 1 is a plan view showing a mounting board according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the mounting board of FIG. 1 as viewed from the II-II direction. FIG. 3 is a diagram illustrating a method of manufacturing a laminate for manufacturing a wiring board on which a light emitting component is mounted. FIG. 4 is a cross-sectional view showing a laminate obtained by the manufacturing method shown in FIG. FIG. 5 is a cross-sectional view showing a wiring board obtained by patterning the conductive layer of the laminate shown in FIG. FIG. 6 is a cross-sectional view illustrating a wiring board further including a reflective layer. FIG. 7 is a diagram illustrating a method of manufacturing a mounting board by mounting a light emitting component. FIG. 8 is a cross-sectional view illustrating an example of a lighting device including a mounting substrate. FIG. 9 is a diagram showing a temperature profile of a reflow step in the example. FIG. 10 is a diagram illustrating evaluation results of a non-lighting rate in Examples 1 to 4 of the embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In the drawings attached to this specification, the scale and the vertical and horizontal dimensional ratios and the like are appropriately changed and exaggerated for convenience of illustration and understanding. Further, in this specification, the terms “substrate” and “sheet” are not distinguished from each other based only on the difference in names. For example, the “substrate” is a concept including members that can be called sheets and films. Further, as used herein, the shapes and geometric conditions and the degree thereof are specified. For example, terms such as "parallel" and "orthogonal" and values of length and angle are strictly limited. Without any limitation, it should be interpreted to include a range in which similar functions can be expected.

  First, a mounting board obtained by mounting the light emitting component 61 on a wiring board will be described with reference to FIGS. As will be described later, the mounting board 60 provided with the light emitting component 61 can constitute a lighting device by being combined with a lighting cover configured as a diffusion plate and a support member such as a base and a housing.

Mounting Board As shown in FIG. 1, the mounting board 60 includes a wiring board 40 having flexibility and functioning as a so-called flexible board, and a plurality of light emitting components 61 mounted on the wiring board 40. I have. The configuration of the light emitting component 61 is not particularly limited as long as a light emitting element that can function as a point light source is provided. For example, a light emitting diode can be used as the light emitting element, and a surface mount type component having a light emitting diode housed in a surface mount type package can be used as the light emitting component 61.

  As described later, the mounting substrate 60 is manufactured by processing a long laminate that is supplied in a state of being wound in a roll shape to produce the wiring substrate 40, and the light emitting component 61 is mounted on the wiring substrate 40. In addition, it is obtained by cutting the wiring board 40 before or after mounting the light emitting component 61. In FIG. 1, the long direction of the laminate and the wiring board 40 is represented by reference numeral D1, and the direction orthogonal to the long direction D1 is represented by reference numeral 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 laminate and the wiring board 40 extend. In the following description, the long 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.

  As shown in FIG. 1, the wiring board 40 may include an extraction electrode unit 43 electrically connected to the light emitting component 61 via a wiring 42 described later. The extraction electrode portion 43 may be formed on the same surface of the surface of the wiring board 40 as the surface on which the light emitting component 61 is mounted, as shown in FIG. May be formed on the surface opposite to the surface on which the is mounted.

  As shown in FIGS. 1 and 2, a region of the wiring board 40 which does not overlap with the light emitting component 61, the mounting electrode portion 41, and the extraction electrode portion 43 when viewed along the normal direction of the resin substrate 21 described later. May be provided with a reflective layer 44 for reflecting light. By providing such a reflective layer 44, the light radiated from the light emitting component 61 and reflected by a diffuser or the like described later and returned to the mounting substrate 60 is reflected by the reflective layer 44, and the external light of the lighting device Can be emitted. Thus, the light use efficiency of the lighting device can be improved. The specific configuration of the reflection layer 44 will be described later.

Wiring Board Next, the configuration of the mounting board 60, particularly the configuration of the wiring board 40 of the mounting board 60, will be described in detail with reference to FIG. The wiring board 40 includes a flexible resin substrate 21, a mounting electrode portion 41 provided on the resin substrate 21, and a wiring 42 connected to the mounting electrode portion 41. The mounting electrode portion 41 is a portion on which the light emitting component 61 is mounted, and is also called a pad or a land. In the following description, of the surfaces of the resin substrate 21, the surface on the side where the mounting electrode portion 41 is provided is referred to as a first surface 21a, and the surface opposite to the first surface 21a is referred to as a second surface 21b. The wiring 42 described above is provided on the first surface 21 a of the resin substrate 21 so as to electrically connect the mounting electrode portion 41 and the extraction electrode portion 43.

  Although FIG. 2 shows an example in which the wiring 42 is provided only on the first surface 21a side of the resin substrate 21, the invention is not limited to this. For example, when the extraction electrode unit 43 is provided on the side opposite to the side on which the light emitting component 61 is mounted as described above, that is, when the extraction electrode unit 43 is provided on the second surface 21b side of the resin substrate 21, the wiring 42 is 21 may be provided on the second surface 21b side. In this case, the mounting electrode portion 41 and the wiring 42 are electrically connected, for example, via a through hole formed in the resin substrate 21.

  In the present embodiment, “flexibility” means that the wiring board 40 is not broken when the wiring board 40 is wound into a roll shape having a diameter of 30 cm at room temperature, for example, at 25 ° C. It means flexibility. The “fold” is a deformation that appears on the wiring board 40 in a direction that intersects the direction in which the wiring board 40 is wound. Even if the wiring board 40 is wound in the reverse direction so as to restore the deformation, Means deformation that does not return. Note that the degree of flexibility of the resin substrate 21 and each of the mounting electrode portion 41 and the wiring 42 is not particularly limited as long as the wiring substrate 40 has flexibility as a whole.

(Resin substrate)
The resin substrate 21 is a flexible substrate made of an insulating resin material. The material constituting the resin substrate 21 and the thickness of the resin substrate 21 are appropriately determined according to characteristics such as flexibility and strength required for the wiring substrate 40. For example, the resin substrate 21 may include a polyester resin such as polyethylene terephthalate or polyethylene naphthalate, an epoxy resin, or a polyimide resin. The thickness of the resin substrate 21 is set, for example, in the range of 10 μm to 300 μm, and more preferably, in the range of 10 μm to 200 μm.

(Mounting electrode part, wiring and extraction electrode part)
As a material forming 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. Note that silver is preferably used in consideration of enhancing the reflection characteristics of the wiring substrate 40.

  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 22, as described later. As long as the mounting substrate 60 has flexibility in a desired direction, 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. 2, an adhesive layer 23 may be interposed between the mounting electrode portion 41 or the wiring 42 and the first surface 21 a of the resin substrate 21. Such an adhesive layer 23 is present when the conductive layer 22 is formed by bonding the metal foil 22a to the resin substrate 21 using the adhesive 23a as described later. When the adhesive layer 23 is not removed when patterning the conductive layer 22 by etching or the like, the adhesive layer 23 is viewed at least partially along the normal direction of the resin substrate 21 as shown in FIG. In this case, it spreads to a region that does not overlap with the mounting electrode portion 41 or the wiring 42. As the adhesive 23a constituting the adhesive layer 23, a known adhesive such as an adhesive containing a resin can be used.

(Reflective layer)
The configuration of the reflective layer 44 is not particularly limited as long as the light returning to the mounting substrate 60 is reflected, and thereby the light use efficiency of the lighting device can be increased. For example, the reflective layer 44 may be configured as a layer containing a reflective white pigment such as a white ceramic material or metal powder. In this case, the reflective layer 44 is formed by first providing a paste containing a reflective white pigment such as a white ceramic material or metal powder on the first surface 21a of the resin substrate 21, and then baking and hardening the paste. Is done. The method for providing the paste on the first surface 21a of the resin substrate 21 is not particularly limited, and a screen printing method or the like can be used as appropriate. Further, the reflection layer 44 may include a base material in which a white pigment, bubbles, and the like are dispersed. In this case, the reflective layer 44 is formed by attaching a base material in which a white pigment, air bubbles, and the like are dispersed inside to the first surface 21a of the resin substrate 21 via an adhesive layer or an adhesive layer (not shown). As the white pigment, white ceramic materials such as titanium oxide, calcium oxide, aluminum oxide, and zinc oxide can be used.

  Preferably, the reflection 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 the regular reflectance and the diffuse reflectance. The total light reflectance can be determined based on the total light reflectance measurement method of JIS K7375. Specifically, the total light reflectance is measured by using a spectrophotometer and an integrating sphere test table at a light wavelength of 380 nm to 780 nm using a spectrophotometer and an integrating sphere test table. It can be determined by measuring at intervals and calculating their average. The total light reflectance is determined as a relative value when the reflectance of a standard white plate containing barium sulfate is 100%.

(Joining layer)
In FIG. 2, reference numeral 62 denotes a portion between the light emitting component 61 and the 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. Represents a bonding layer interposed between the layers. As a material for forming the bonding layer 62, for example, cream solder applied on the mounting electrode portion 41 in a reflow process can be given. The cream solder includes a binder material such as a flux, and metal powder dispersed in the binder material and melted during the reflow process. Although FIG. 2 shows an example in which the bonding layer 62 is clearly interposed between the light emitting component 61 and the mounting electrode portion 41, 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 electrically connected to the mounting electrode portion 41 by coupling the light emitting component 61 to the mounting electrode portion 41.

  By the way, in the reflow step, at least the mounting electrode portion 41 of the wiring board 40 and its peripheral portion are heated to a temperature at least equal to or higher than the melting point of the solder included in the bonding layer 62. In the following description, the maximum value of the temperature reached by the heated wiring board 40 is also referred to as the reached temperature. In the wiring substrate 40 according to the present embodiment, when the attained temperature increases, the above-described precipitation of the oligomer and discoloration of the reflective layer 44 are likely to occur, and as a result, it is considered that the reflectance of the wiring substrate 40 decreases. . Therefore, it is preferable to set the temperature at the time of performing the reflow process as low as possible, thereby lowering the temperature reached by the wiring board 40.

  In view of such a point, 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 included in the bonding layer 62. . In this case, the ultimate temperature of the wiring substrate 40 can be set to 180 ° C. or lower, more preferably 150 ° C. or lower, whereby the oligomer is deposited on the surface of the resin substrate 21 and the reflection layer 44 is discolored. Can be suppressed.

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

  Next, the operation and effect of the present embodiment having such a configuration will be described. Here, a method for manufacturing the above-described wiring board 40 by processing a long laminated body and mounting the light emitting component 61 on the wiring board 40 to manufacture the above-described mounting board 60 will be described.

(Production method of laminate)
First, a method of manufacturing the laminate 20 for manufacturing the wiring board 40 will be described with reference to FIGS. FIG. 3 is a diagram illustrating a laminated body manufacturing apparatus 10 for manufacturing the laminated body 20.

  First, as shown in FIG. 3, a first unwinding portion 11 for holding a long resin substrate 21 wound in a roll shape, and a second unwinding portion 11 for holding a long metal foil 22a wound in a roll shape. The unwinding unit 12 is prepared. Next, the resin substrate 21 is unwound from the first unwinding part 11, and the metal foil 22a is unwound from the second unwinding part 12. Further, an adhesive is applied on at least one surface of the resin substrate 21 or the metal foil 22a. FIG. 3 shows an example in which the adhesive 23a is applied from the application unit 13 on the surface of the metal foil 22a facing the resin substrate 21. After that, the resin substrate 21 and the metal foil 22a are adhered to each other via the adhesive 23a in the laminated portion 14. Thereby, a laminate 20 including the resin substrate 21, the conductive layer 22, and the adhesive layer 23 interposed between the resin substrate 21 and the conductive layer 22 is obtained. FIG. 4 is a cross-sectional view illustrating the stacked body 20.

  The laminating unit 14 is configured as, for example, a laminating roll that presses the metal foil 22a toward the resin substrate 21. The laminate 20 is wound by the winding unit 15 as shown in FIG.

(Wiring board manufacturing method)
Next, the wiring board 40 is manufactured by processing the above-described laminated body 20. FIG. 5 is a cross-sectional view showing a wiring board 40 including a mounting electrode portion 41 and a wiring 42 obtained by patterning the conductive layer 22 of the laminate 20.

  As a method of patterning the conductive layer 22, a method of etching the conductive layer 22 using a photosensitive layer provided on the conductive layer 22 in a pattern corresponding to the mounting electrode portion 41 or the wiring 42 as a mask, or a method of patterning the mounting electrode portion 41 A known method such as a laser ablation method of irradiating the conductive layer 22 with a laser in a pattern corresponding to the wiring 42 or the like can be used as appropriate.

  When an etching method is adopted as a method of patterning the conductive layer 22, the conductive layer 22 is removed but the adhesive layer 23 between the conductive layer 22 and the resin substrate 21 is not removed depending on an etchant used. There is. In this case, the adhesive layer 23 extends to a region that does not overlap with the mounting electrode portion 41 or the wiring 42 when viewed along the normal direction of the resin substrate 21. For example, in FIG. 5, the adhesive layer 23 remains over the entire area of the wiring board 40.

  Thereafter, as shown in FIG. 6, a reflection layer 44 for reflecting light is formed in a region on the first surface 21a side of the resin substrate 21 which does not overlap with the mounting electrode portion 41 and the light emitting component 61 to be mounted later. It may be provided. As a method of providing the reflection layer 44, a screen for applying a coating liquid containing a white pigment, a metal powder, or the like using a metal mask having an opening formed at a position corresponding to a region where the reflection layer 44 is to be formed. A printing method or the like can be used.

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

  First, as shown in FIG. 7, an unwinding portion 51 for holding a long wiring substrate 40 wound in a roll is prepared. Next, the wiring board 40 is unwound from the unwinding part 51. Next, as shown in FIG. 7, a bonding layer 62 is provided on the mounting electrode portion 41 of the wiring board 40. For example, using the application unit 52, cream solder for forming the bonding layer 62 is applied on the mounting electrode unit 41. Thereafter, a mounting step of mounting the light emitting component 61 on the mounting electrode portion 41 provided with the bonding layer 62 is performed using the mounting portion 53. Specifically, first, the light emitting component 61 is mounted on the mounting electrode portion 41 provided with the bonding layer 62, and then the mounting electrode portion of the wiring board 40 on which at least the light emitting component 61 is mounted. The portion 41 is heated to melt the bonding layer 62. Thereby, the light emitting component 61 is joined to the mounting electrode portion 41. Next, using the cutting portion 54, the wiring board 40 on which the light emitting component 61 is mounted is cut in a second direction D2 orthogonal to the first direction D1. Thereby, the mounting board 60 shown in FIG. 2 described above can be obtained.

  Here, according to the present embodiment, as described above, a solder containing a low-melting-point solder that melts at a temperature of 180 ° C. or less is used as the cream solder applied on mounting electrode portion 41. Therefore, the temperature reached by the wiring board 40 during the mounting process can be set to 180 ° C. or less. Thereby, it is possible to suppress the oligomer from being precipitated on the surface of the resin substrate 21 and the discoloration of the reflective layer 44 due to the heating during the mounting process. Thus, it is possible to suppress a decrease in the reflectance of the wiring board 40 due to heating during the mounting process.

  In addition, according to the present embodiment, the temperature reached by wiring substrate 40 during the mounting process can be set to 180 ° C. or less, so that the resin material forming resin substrate 21 of wiring substrate 40 has heat resistance. It is possible to use a lower one. That is, the degree of freedom in selecting the resin substrate 21 increases. Further, a resin material having relatively low heat resistance, such as a polyester resin, an epoxy resin, or a polyimide resin, can be used. Therefore, the cost required for the resin substrate 21 can be reduced as compared with the case where the resin substrate 21 is formed using a resin material having high heat resistance.

(Method of manufacturing lighting device)
Thereafter, a step of attaching the wiring board 40 on which the light emitting components 61 are mounted to the support member 81 may be performed. Thereby, as shown in FIG. 8, it is possible to obtain a lighting device 80 including the mounting board 60 and the support member 81 attached to the mounting board 60 on the second surface 21b side of the resin board 21. As shown in FIG. 8, the lighting device 80 further includes a diffusion plate 82 provided at a distance from the mounting board 60 on the side of the mounting board 60 on which the light emitting component 61 is mounted. Is also good. As the diffusion plate 82, a lighting cover or the like functioning as a light diffusing agent may be used.

  In FIG. 8, the arrow denoted by reference numeral L1 indicates light emitted from the light emitting component 61. Most of the light L1 emitted from the light emitting component 61 and 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, light incident on the diffusion plate 82 along a direction inclined from the normal direction of the diffusion plate 82 is reflected by the diffusion plate 82 as shown in FIG. May return to the mounting board 60. Most of such return light is reflected by the reflective layer 44 and travels again to the diffusion plate 82 as shown by an arrow L21 in FIG. 8, and then passes through the diffusion plate 82 to reach the user side. Further, as shown by an arrow L22 in FIG. 8, the other return light is reflected by the first surface 21a of the resin substrate 21 after passing through the reflective layer 44, travels to the diffusion plate 82 again, and passes through the diffusion plate 82. To the user side. Here, according to the present embodiment, as described above, the discoloration of the reflective layer 44 and the precipitation of the oligomer on the surface of the resin substrate 21 are suppressed. Therefore, the reflection of the return light L21 on the reflection layer 44 and the reflection of the return light L22 on the first surface 21a of the resin substrate 21 can be generated with high reflectance. Thus, the light use efficiency of the lighting device 80 can be improved.

  In the present embodiment, as shown in FIG. 8, the adhesive layer 23 extends to a region that does not overlap with the mounting electrode portion 41 or the wiring 42 when viewed along the normal direction of the resin substrate 21. Sometimes. Therefore, if the temperature reached by the wiring board 40 during the mounting process is high, the adhesive layer 23 may be discolored or oligomers may be deposited on the surface of the adhesive layer 23 due to heating during the mounting process. In this case, the reflection of the return light L22 transmitted through the reflective layer 44 is impeded by the adhesive layer 23. Here, according to the present embodiment, as described above, the temperature reached by wiring substrate 40 during the mounting process can be set to 180 ° C. or lower. Therefore, it is possible to suppress not only deterioration of the optical characteristics of the resin substrate 21 and the reflection layer 44 but also deterioration of the optical characteristics of the adhesive layer 23. Therefore, even when the adhesive layer 23 extends to a region that does not overlap with the mounting electrode portion 41 or the wiring 42, it is possible to prevent the reflection characteristics of the wiring substrate 40 from being impaired due to the adhesive layer 23. can do.

  Note that various changes 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, portions that can be configured in the same manner as in the above-described embodiment will use the same reference numerals as those used for corresponding portions in the above-described embodiment, A duplicate description will be omitted. Further, when it is clear that the operation and effect obtained in the above-described embodiment can be obtained also in the modification, the description thereof may be omitted.

(Modified example of wiring board)
In the above-described embodiment, an example has been described in which a white pigment for imparting reflection characteristics to the wiring substrate 40 is included in the reflection layer 44 provided on the first surface 21 a side of the resin substrate 21. That is, an example has been described in which the reflection characteristics for reflecting the light returning to the wiring substrate 40 are imparted to the mounting substrate 60 by the reflection layer 44 provided on the first surface 21a side of the resin substrate 21. However, the present invention is not limited to this, and the resin substrate 21 itself may have such reflection characteristics. For example, as the resin substrate 21, a resin substrate in which a white pigment, bubbles, and the like are included and dispersed may be used. The method for manufacturing the resin substrate 21 having such reflection characteristics is not particularly limited, and a known method can be used as appropriate. For example, pellets as a raw material of a resin material and a white pigment are mixed and melted, and these mixed materials are formed by extrusion molding or the like, and are fired as necessary to provide flexibility and reflection characteristics. The resin substrate 21 can be obtained. In this case, even if the reflection layer 44 is not provided on the first surface 21a of the resin substrate 21, the light returning to the wiring substrate 40 can be reflected with a sufficiently high reflectance. When the resin substrate 21 contains a white pigment, bubbles, or the like, the resin substrate 21 is preferably configured such that the total light reflectance within the light wavelength range of 380 nm to 780 nm is within the range of 60% to 99%. Is done.

  Note that, in the present embodiment, the form intended by the description that “the wiring substrate 40 contains a white pigment or bubbles” includes the form in which the reflective layer 44 on the resin substrate 21 contains the white pigment. In addition, both forms in which the white pigment or bubbles are included in the resin substrate 21 itself are included.

(Other modifications)
Further, in the above-described embodiment, an 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. After the wiring board 40 is cut, the light emitting components 61 may be mounted on the single wiring board 40.

  Although some modifications to the above-described embodiment have been described, it is needless to say that a plurality of modifications can be appropriately combined and applied.

  The result of evaluating the advantage of mounting a light-emitting component using a low-melting-point solder on a wiring board having a flexible resin substrate will be described below.

(Example 1)
First, a resin substrate made of polyethylene terephthalate (hereinafter, also referred to as PET), a conductive layer provided on a first surface of the resin substrate and made of copper (hereinafter, also called Cu), and a second substrate of the resin substrate And a metal layer made of aluminum (hereinafter, also referred to as Al). Next, a wiring board provided with a resin substrate made of PET was manufactured by patterning the conductive layer made of Cu using an etching method to form a mounting electrode portion. The thickness of the resin substrate made of PET was 25 μm, the thickness of the conductive layer made of Cu, that is, the thickness of the mounting electrode portion was 35 μm, and the thickness of the metal layer made of Al was 100 μm.

  After that, the light emitting component including the light emitting diode was mounted on the mounting electrode portion of the wiring board. Specifically, first, a paste of a low melting point solder (hereinafter, also referred to as SnBi solder) containing tin and bismuth and having a melting point of 150 ° C. or less was applied onto the mounting electrode portion. Thereafter, a reflow process was performed with the temperature profile shown in FIG. 9 to obtain a mounting board on which the light emitting components were mounted.

  In the reflow step, as shown in FIG. 9, first, the ambient temperature around the wiring board was raised to about 100 ° C., and the state was maintained for about 60 seconds. Next, the ambient temperature around the wiring substrate was raised to about 145 ° C., and the state was maintained for about 40 seconds. Thereafter, the atmosphere around the wiring board was cooled. In FIG. 9, the symbol “CH_A” represents the temperature of the channel A set to measure the temperature at the leading position of the wiring board in the transport direction during the reflow process, and the symbol “CH_B” represents the wiring board. Represents the temperature of the channel B set to measure the temperature at the center position of the wiring board, and the symbol “CH_C” is set to measure the temperature at the rear end position of the wiring board in the transport direction during the reflow process. The temperature of the channel C is shown.

  A reliability test was performed on the mounting board obtained as described above. Specifically, 1000 cycles of a temperature cycle test in which the temperature of the mounting substrate was changed in the order of room temperature → + 125 ° C. → −40 ° C. → room temperature. Thereafter, it was checked whether the light emitting component was normally lit and whether the SnBi solder had cracks. As a result, the light emitting component was normally lit, and no crack was generated in the SnBi solder.

(Example 2)
First, a resin substrate made of PET was prepared. Next, a conductive paste containing silver (hereinafter, also referred to as Ag) was printed on the first surface of the resin substrate in a pattern corresponding to the mounting electrode portion. Thus, a wiring board provided with the resin substrate made of PET was manufactured. The thickness of the resin substrate made of PET was 25 μm, and the thickness of the mounting electrode portion made of Ag was 10 μm.

  Thereafter, similarly to the case of Example 1 described above, the light emitting component including the light emitting diode was mounted on the mounting electrode portion of the wiring board using SnBi solder which is a low melting point solder. Further, in the same manner as in Example 1 described above, a reliability test was performed on the mounting board on which the light emitting components were mounted. As a result, the light emitting component was normally lit, and no crack was generated in the solder.

(Example 3)
First, a wiring board provided with a resin substrate made of a glass epoxy resin (hereinafter, also referred to as a glass epoxy substrate) was prepared. Next, as in the case of Example 1 described above, the light emitting component including the light emitting diode was mounted on the mounting electrode portion of the wiring board using SnBi solder which is a low melting point solder. The thickness of the glass epoxy substrate was 1000 μm.

  Thereafter, similarly to the case of Example 1 described above, the light emitting component including the light emitting diode was mounted on the mounting electrode portion of the wiring board using SnBi solder which is a low melting point solder. Further, in the same manner as in Example 1 described above, a reliability test was performed on the mounting board on which the light emitting components were mounted. As a result, at the end of 1000 cycles, about 62% of the mounted light emitting components did not light up normally. In the following description, the ratio of the light emitting components that did not light up normally among the mounted light emitting components is also referred to as a non-lighting rate.

(Example 4)
Except for using a general solder containing tin, silver and copper and having a melting point of about 260 ° C. (hereinafter also referred to as SnAgCu solder), and performing a reflow process with a temperature profile capable of melting the SnAgCu solder, In the same manner as in Example 3, the light emitting component was mounted on the mounting electrode portion of the wiring board. Thereafter, in the same manner as in Example 1 described above, a reliability test was performed on the mounting board on which the light emitting components were mounted. As a result, at the end of 500 cycles, the non-lighting rate was about 18%. At the end of 1000 cycles, the non-lighting rate was about 88%.

  FIG. 10 collectively shows the evaluation results of the non-lighting rates in Examples 1 to 4.

As described above, in Examples 1 and 2 in which the wiring substrate was formed using the resin substrate made of PET and the mounting substrate was manufactured using SnBi solder which is a low melting point solder, the mounting substrate had high reliability. Had. On the other hand, in Example 3 in which the wiring substrate was formed using the glass epoxy substrate and the mounting substrate was manufactured using SnBi solder, which is a low melting point solder, the reliability of the mounting substrate was insufficient. There can be various reasons for this. One of the reasons is, for example, that the thickness of an element constituting the mounting board is influenced.
Table 1 shows the coefficient of thermal expansion in the width direction and the coefficient of thermal expansion in the thickness direction of the above-described SnBi solder, glass epoxy substrate, and PET, respectively. Table 1 also shows data on SnAgCu solder, Al, Cu and Ag for reference.

  As shown in Table 1, the thickness of the glass epoxy substrate is significantly larger than the thickness of PET. It is considered that such a factor has caused a decrease in the reliability of the mounting board according to Example 3.

  In consideration of the above matters, when a mounting board is manufactured using a low melting point solder such as SnBi solder, the thickness of the wiring board is small and the difference between the coefficient of thermal expansion in the width direction and the coefficient of thermal expansion in the thickness direction is small. It is considered preferable to use one provided with a small resin substrate. For example, it is considered suitable to use a resin substrate having a thickness of 300 μm or less, more preferably 200 μm or less.

Reference Signs List 20 laminated body 21 resin substrate 22 conductive layer 22a metal foil 23 adhesive layer 23a adhesive 40 wiring board 41 mounting electrode section 42 wiring 44 reflection layer 60 mounting board 61 light emitting component 62 bonding layer 80 lighting device

Claims (4)

A method of manufacturing a mounting board on which a light emitting component is mounted,
A resin substrate made of a polyester resin, an epoxy resin, or a polyimide resin having flexibility and having white pigments or bubbles dispersed therein, a mounting electrode portion provided on the resin substrate, and the mounting electrode portion wherein the adhesive layer is interposed between the resin substrate, provided in a region where the does not overlap with the mounting electrode part and the light emitting part when viewed along the normal direction of the resin substrate, at least in part and A step of preparing a wiring board comprising: a reflective layer that overlaps with the adhesive layer and has a white pigment dispersed therein;
Mounting a light emitting component on the mounting electrode portion of the wiring board,
The mounting step is a step of providing a bonding layer on the mounting electrode section, a step of mounting the light emitting component on the mounting electrode section provided with the bonding layer, and heating the wiring board. Melting the bonding layer,
The bonding layer may include tin and bismuth, viewed contains a low melting point solder melts at 0.99 ° C. below the temperature,
The method of manufacturing a mounting substrate, wherein the adhesive layer extends at least partially to a region that does not overlap with the mounting electrode portion and the reflective layer when viewed along a normal direction of the resin substrate .   The method according to claim 1, wherein a thickness of the resin substrate is in a range of 10 μm to 300 μm. A mounting board on which a light emitting component is mounted,
A resin substrate made of a polyester resin, an epoxy resin, or a polyimide resin having flexibility and having white pigments or bubbles dispersed therein, a mounting electrode portion provided on the resin substrate, and the mounting electrode portion wherein the adhesive layer is interposed between the resin substrate, provided in a region where the does not overlap with the mounting electrode part and the light emitting part when viewed along the normal direction of the resin substrate, at least in part and A wiring board comprising a reflective layer, which is superimposed on the adhesive layer, and in which a white pigment is dispersed,
A light-emitting component mounted on the mounting electrode portion of the wiring board,
A bonding layer is interposed between the mounting electrode portion and the light emitting component of the wiring board,
The bonding layer may include tin and bismuth, viewed contains a low melting point solder melts at 0.99 ° C. below the temperature,
The mounting substrate, wherein the adhesive layer at least partially extends to a region that does not overlap the mounting electrode portion and the reflective layer when viewed along a normal direction of the resin substrate.   The mounting board according to claim 3, wherein the thickness of the resin board is in a range of 10 μm to 300 μm.