JP2012074527A - Substrate for led mounting and led backlight provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for LED mounting which is excellent in heat dissipation performance.SOLUTION: A substrate for LED mounting on which an LED 2 is mounted comprises: an aluminum plate 1 for heat dissipation; a wiring pattern 5 which is electrically connected to an electrode of the LED via a solder, etc. when the LED is mounted; and an insulating layer 4 for insulating between the aluminum plate and the wiring pattern. At least one surface of the substrate for LED mounting is coated with a resist 3 which protects the wiring pattern from dust and moisture and prevents the solder from adhering to unnecessary areas, and a heat dissipation paint 9 which has heat dissipating effect.

Description

  The present invention relates to an LED mounting substrate and an LED backlight including the same, and more particularly to a heat dissipation measure applied to them.

  In order to obtain high luminance in the LED, it is necessary to flow a large amount of current. However, the light emission of the LED is accompanied by heat generation, and the amount of heat generated increases as the current flowing through the LED increases.

  It is a well-known fact that the brightness of an LED decreases as the temperature increases. For this reason, for example, in designing an LED backlight, when determining the number of LEDs necessary to obtain a desired high luminance, it is necessary to consider a decrease in luminance due to an increase in LED temperature. In other words, the higher the LED temperature when obtaining the desired high brightness, the greater the number of necessary LEDs, and conversely, the LED temperature when obtaining the desired high brightness by taking heat dissipation measures. The lower the number is, the smaller the number of necessary LEDs can be.

  In addition, since LEDs are vulnerable to heat, there is also a problem that the lifetime of the LEDs is shortened unless heat dissipation measures are taken.

  As described above, heat dissipation measures are very important for LEDs. As a heat dissipation measure for the LED, it is conceivable to provide a heat dissipation device such as a heat sink on the LED mounting substrate. However, in an electronic device (for example, a liquid crystal display device) that is becoming thinner, it is practically difficult to provide a thick heat dissipation device on the LED mounting substrate due to the structure of the device.

JP 58-123575 A (Claim 4) JP 2004-43612 A (paragraph 0016)

  For this reason, in an LED backlight mounted on a liquid crystal display device, a heat dissipation measure using a heat-dissipating aluminum plate for the LED mounting substrate has become common. A conventional example of such an LED mounting substrate is shown in FIGS. 10A and 10B. 10A is a top view of a conventional LED mounting substrate, and FIG. 10B is a partial side cross-sectional view of the conventional LED mounting substrate taken along the dashed line in FIG. 10A.

  10A and 10B, the LED mounting substrate of the conventional example is a wiring that is electrically connected to the electrodes of the LED 2 via solder or the like (not shown) when the heat radiating aluminum plate 1 and the LED 2 are mounted. The pattern 5, the insulating layer 4 for insulating the aluminum plate 1 and the wiring pattern 5, and the resist 3 that protects the wiring pattern 5 from dust and moisture and prevents the solder from adhering to unnecessary portions.

  Most of the heat generated in the LED 2 when the LED 2 is turned on is transferred from the electrode of the LED 2 to the aluminum plate 1 via the wiring pattern 5 and the insulating layer 4 such as solder, and is radiated by the aluminum plate 1. Therefore, it is considered that the temperature rise around the portion surrounded by the dotted line in FIG.

  The LED of the LED backlight mounted on the liquid crystal display device has a large output, and the conventional LED mounting substrate shown in FIGS. 10A and 10B has a sufficient heat dissipation effect for such a high output LED module. Can't get. For this reason, the amount of current supplied to the LEDs is limited to reduce the brightness of the individual LEDs, thereby suppressing the heat generation of the LEDs. At present, the number of is increasing.

  In addition, as described in Patent Document 2, in the structure in which the heat dissipating paint is applied to both the inner surface and the outer surface of the casing of the electronic / electric device or only the inner surface, the portion surrounded by the dotted line in FIG. 10B That is, the temperature rise around the electrode installation location of the LED 2 cannot be effectively suppressed.

  An object of this invention is to provide the board | substrate for LED mounting excellent in heat dissipation, and an LED backlight provided with the same in view of said situation.

  In order to achieve the above object, an LED mounting substrate according to the present invention is an LED mounting substrate on which an LED is mounted, and there is a region where a heat radiation paint is applied to at least one surface of the LED mounting substrate. It is set as such.

  According to such a configuration, since the heat dissipating paint is applied, the heat dissipating property is superior to that of the conventional LED mounting substrate.

  In addition, the LED mounting surface side of the LED mounting substrate has a portion corresponding to a portion directly below the LED when the LED is mounted (the LED side is an upward direction and the LED mounting substrate side is a downward direction). It is preferable that one groove is formed and the first groove is filled with the heat radiation paint.

  According to such a configuration, since the amount of the heat dissipating paint located immediately below the LED is increased, the heat dissipating effect is increased.

  In addition, a second groove is formed in a portion of the LED mounting substrate opposite to the LED mounting surface at a portion corresponding to a position directly below the LED when the LED is mounted, and the heat dissipation paint is formed in the second groove. It is preferable that it is filled.

  According to such a structure, since the quantity of the thermal radiation coating material located in the part directly under LED increases further, the thermal radiation effect becomes still larger.

  Moreover, it is preferable that a through hole is provided for communicating the first groove and the second groove, and the heat radiation paint is filled in the through hole.

  According to such a configuration, since the coating area of the heat dissipating paint is increased, the heat dissipating effect is increased.

  Moreover, it is preferable that a layer of a material having a higher thermal conductivity than the substrate body is formed on the inner wall surface of the through hole.

  According to such a configuration, heat transfer between the heat-dissipating paint filled in the through hole and the substrate body becomes good, so that heat can be radiated more efficiently.

  In order to achieve the above object, an LED backlight according to the present invention includes an LED and an LED mounting substrate having any one of the above configurations for mounting the LED.

  The LED mounting substrate according to the present invention has a structure in which a region where a heat radiation paint is applied is present on at least one surface of the LED mounting substrate, and thus has superior heat dissipation compared to the LED mounting substrate of the conventional example. Yes. As a result, the LED mounting substrate according to the present invention simultaneously achieves higher brightness and longer life of the LED and space saving of the LED mounting substrate that could not be solved by the conventional LED mounting substrate. be able to.

It is a top view of the board | substrate for LED mounting which concerns on one Embodiment of this invention. It is a partial sectional side view of the board | substrate for LED mounting which concerns on one Embodiment of this invention. It is a graph which shows the thermal radiation effect of a thermal radiation coating material. It is a figure which shows the principal part structural example of a liquid crystal television receiver provided with an edge type | mold LED backlight. It is a fragmentary sectional side view which shows the 1st modification of the board | substrate for LED mounting which concerns on one Embodiment of this invention. It is a fragmentary sectional side view which shows the 2nd modification of the board | substrate for LED mounting which concerns on one Embodiment of this invention. It is a fragmentary sectional side view which shows the 3rd modification of the board | substrate for LED mounting which concerns on one Embodiment of this invention. It is a fragmentary sectional side view which shows the 4th modification of the board | substrate for LED mounting which concerns on one Embodiment of this invention. It is a fragmentary sectional side view which shows the 5th modification of the board | substrate for LED mounting which concerns on one Embodiment of this invention. It is a fragmentary sectional side view which shows the 6th modification of the board | substrate for LED mounting which concerns on one Embodiment of this invention. It is a top view of the board | substrate for LED mounting of a prior art example. It is a fragmentary sectional side view of the board | substrate for LED mounting of a prior art example.

  Embodiments of the present invention will be described below with reference to the drawings.

  A configuration of an LED mounting substrate according to an embodiment of the present invention will be described with reference to FIGS. 1A and 1B. 1A is a top view of an LED mounting substrate according to an embodiment of the present invention, and FIG. 1B is a partial side cross-sectional view of an LED mounting substrate according to an embodiment of the present invention cut along a dashed line in FIG. 1A. It is.

  1A and 1B, the LED mounting substrate according to an embodiment of the present invention is electrically connected to the electrodes of the LED 2 via solder or the like (not shown) when the heat-dissipating aluminum plate 1 and the LED 2 are mounted. A wiring pattern 5 connected to the substrate, an insulating layer 4 for insulating the aluminum plate 1 and the wiring pattern 5, and a resist 3 for protecting the wiring pattern 5 from dust and moisture and preventing solder from adhering to unnecessary portions, A heat dissipating paint 9 is provided.

What is necessary is just to produce the board | substrate for LED mounting which concerns on one Embodiment of this invention shown to FIG. 1A and FIG. 1B, for example in the procedure shown below.
(1) The insulating layer 4 is formed on the entire surface of the aluminum plate 1. It is desirable that the insulating layer 4 is as thin as possible and can ensure insulation between the upper and lower sides of the insulating layer 4.
(2) Next, a first resist is formed in a predetermined region on the insulating layer 4 (a region other than the region where the groove 6 is formed), and etching is performed using the first resist as a mask until the surface of the aluminum plate 1 is exposed. I do. The portion cut by the etching becomes the groove 6. Then, after forming the groove 6, the first resist is removed.
(3) Next, a wiring layer is formed on the entire surface of the aluminum plate 1, and a second resist is formed in a predetermined region (region where the wiring pattern 5 is formed). Thereafter, etching is performed, and the wiring pattern 5 is formed by removing the second resist after completion of the etching. Then, a third resist (a region excluding two regions of the wiring pattern 5 where a portion that needs to be soldered to the LED 2 and the region of the groove 6 is excluded) on the surface side of the aluminum plate 1 is provided. Resist 3) is formed.
(4) Next, a fourth resist is formed in a predetermined region (a region other than the region where the groove 7 is formed) on the back surface of the aluminum plate 1, and the back surface of the aluminum plate 1 is etched using the fourth resist as a mask. . A portion cut by the etching becomes a groove 7. Then, after the groove 7 is formed, the fourth resist is removed.
(5) Next, six through-holes 8 for communicating the grooves 6 and 7 are formed per LED 2 by drilling or laser processing. Thereafter, copper plating is applied to the inner wall surface of the through hole 8.
(6) Finally, an insulative heat dissipating paint 9 is poured into the grooves 6, 7, and through holes 8, and the insulative heat dissipating paint 9 is applied on the resist 3 and the entire back surface of the aluminum plate 1. To do.

  The heat dissipating paint 9 is a paint having a heat dissipating effect as shown in FIG. In FIG. 2, the horizontal axis is the elapsed time from the start of heat input to the heat radiating aluminum plate, the vertical axis is the temperature of the heat radiating aluminum plate, and the solid line is the case where the heat radiating aluminum plate is not coated with heat radiating paint. The temperature characteristic is shown, and the dotted line shows the temperature characteristic when the heat-dissipating paint is applied to the heat-dissipating aluminum plate. As can be seen from the temperature characteristics shown in FIG. 2, the heat dissipating paint 9 can suppress the temperature rise of the aluminum plate that is generating heat.

  Since the LED mounting substrate according to the embodiment of the present invention shown in FIGS. 1A and 1B has a configuration in which the heat dissipating paint 9 is applied, the heat dissipation is superior to the LED mounting substrate of the conventional example.

  Further, in the LED mounting substrate according to the embodiment of the present invention shown in FIGS. 1A and 1B, not only the front surface side of the aluminum plate 1 (the mounting surface side of the LED 2) but also the back surface side of the aluminum plate 1. 9 is applied, the heat dissipation effect is greater than the configuration in which the heat dissipation paint 9 is applied only to the surface side of the aluminum plate 1 (the mounting surface side of the LED 2).

  Further, in the LED mounting substrate according to the embodiment of the present invention shown in FIGS. 1A and 1B, grooves 6 and 7 are formed on the both sides of the substrate directly under the LED 2, and the grooves 6 and 7 are filled with the heat radiation paint 9. As a result, the amount of the heat radiation paint 9 located immediately below the LED 2 is increased, so that the heat radiation effect is greater than the configuration without such a groove.

  Further, in the LED mounting substrate according to the embodiment of the present invention shown in FIGS. 1A and 1B, the through holes 8 communicate with the grooves 6 and 7 formed in the portions immediately below the LEDs 2 on both surfaces of the substrate. When the heat radiation paint 9 is filled in, the coating area of the heat radiation paint 9 on the aluminum plate 1 is increased, so that the heat radiation effect is greater than in the configuration in which the through hole 8 is not provided. Furthermore, since some of the through holes 8 (two per LED 2) are formed in the vicinity of the electrode installation location of the LED 2 that is considered to have a large temperature rise, heat is efficiently dissipated. Then, by forming copper plating having higher thermal conductivity than the aluminum plate 1 on the inner wall surface of the through hole 8, heat transfer between the heat radiation paint 9 filled in the through hole 8 and the aluminum plate 1 is good. Therefore, heat dissipation is performed more efficiently.

  Here, a configuration example of a main part of a liquid crystal television receiver including an edge type LED backlight will be described with reference to FIG.

  The edge type LED backlight of the liquid crystal television receiver shown in FIG. 3 includes a first LED module 10 for LED backlight which is a series connection circuit of a plurality of LEDs, and an LED backlight which is also a series connection circuit of a plurality of LEDs. The second LED module 11 and the light guide plate 12 are configured.

  The first LED module for LED backlight 10 and the second LED module for LED backlight 11 are connected in parallel, and are driven (lighted) by the drive voltage output from the LED driver 13. The light guide plate 12 guides the light emitted from the first LED module 10 for LED backlight and the second LED module 11 for LED backlight to the liquid crystal display panel 14.

  The edge type LED backlight of the liquid crystal television receiver shown in FIG. 3 has two LED mounting boards (not shown in FIG. 3). The LEDs of the first LED module 10 for LED backlight are mounted on one LED mounting board, and the LEDs of the second LED module 11 for LED backlight are mounted on the other LED mounting board. 1A and 1B, the LED mounting substrate according to the embodiment of the present invention is shown in FIG. 1A and FIG. 1B only in a region where two LEDs are mounted. The structure pattern shown in (4) is repeated by the number corresponding to the number of LEDs constituting the LED module.

  As mentioned above, although embodiment which concerns on this invention was described, the range of this invention is not limited to this, A various change can be added and implemented in the range which does not deviate from the main point of invention.

  For example, in the embodiment described above, six through holes are formed per LED, but the number of through holes per LED may not be six. In the above-described embodiment, the inner wall surface of the through hole is plated with copper. However, a material other than copper may be used as long as the material has higher thermal conductivity than the substrate.

  In the above-described embodiment, an insulating heat radiation paint is used for the heat radiation paint 9, but when a conductive heat radiation paint is used for the heat radiation paint 9, a modification as shown in FIG. In the configuration shown in FIG. 4, the wiring pattern 5 and the heat dissipating paint 9 filled in the groove 6 are insulated by the insulating layer 4.

  In the above-described embodiment, the aluminum plate 1 is used as a substrate. However, due to the improvement in heat dissipation according to the present invention, an insulating substrate that is inferior in heat dissipation than the aluminum plate 1 (for example, a phenel substrate or a glass epoxy substrate). Can be used, for example, the deformation as shown in FIG. In FIG. 5, reference numeral 15 denotes an insulating substrate.

  Similarly to the modification shown in FIG. 5, the heat dissipation is inferior to the LED mounting substrate according to the embodiment of the present invention shown in FIGS. 1A and 1B. However, as shown in FIG. 6, the LED mounting substrate having a configuration in which the heat dissipating paint 9 is not applied except for the groove 7 and the through hole 8, and the LED mounting substrate having a configuration in which the groove 6 and the groove 7 are not communicated as shown in FIG. As shown in FIG. 9, the LED mounting substrate having a configuration in which the heat dissipating paint 9 is applied only to the front surface side (the mounting surface side of the LED 2) of the aluminum plate 1, the LED mounting substrate having a configuration in which grooves and through holes are not formed as shown in FIG. Are also included in the present invention.

1 Aluminum plate 2 LED
DESCRIPTION OF SYMBOLS 3 Resist 4 Insulating layer 5 Wiring pattern 6, 7 Groove 8 Through hole 9 Heat radiation paint 10 1st LED module for LED backlight 11 2nd LED module for LED backlight 12 Light guide plate 13 LED driver 14 Liquid crystal display panel 15 Insulating board

Claims (6)

An LED mounting board on which LEDs are mounted,
An LED mounting substrate, wherein a region where a heat radiation paint is applied exists on at least one surface of the LED mounting substrate.   On the LED mounting surface side of the LED mounting substrate, a first groove is formed in a portion corresponding to a position immediately below the LED when the LED is mounted, and the heat dissipation paint is filled in the first groove. The board | substrate for LED mounting of Claim 1 characterized by these.   On the opposite side of the LED mounting surface of the LED mounting substrate, a second groove is formed in a portion corresponding to the LED immediately below when the LED is mounted, and the heat dissipation paint is filled in the second groove. The board | substrate for LED mounting of Claim 2 characterized by the above-mentioned.   4. The LED mounting substrate according to claim 3, wherein a through hole is provided to communicate the first groove and the second groove, and the heat dissipation paint is filled in the through hole.   The LED mounting substrate according to claim 4, wherein a layer of a material having a higher thermal conductivity than the substrate body is formed on an inner wall surface of the through hole.   An LED backlight comprising: an LED; and the LED mounting substrate according to claim 1 on which the LED is mounted.