JP2009010050A - Light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device capable of increasing its cooling efficiency while suppressing deterioration in its mechanical strength. <P>SOLUTION: The light source device 1 is equipped with a supporting board 2 and a plurality of LED chips 3 mounted on the supporting board 2, wherein the supporting board 2 is thermally connected to a cooling means 4 disposed opposite to the LED chips 3 on the supporting board 2. The supporting board 2 comprises a base sheet 20 arranging the LED chips 3 on one surface in the thickness direction and a frame 21 having an opening 21a to expose the LED chips 3 and connected to the surface of the base sheet 20 to reinforce the base sheet 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light source device using a light emitting diode chip.

  Conventionally, a light source device using a discharge lamp, a laser oscillator, or the like as a light source has been provided. In recent years, a light-emitting diode (hereinafter referred to as an LED) is used instead of a discharge lamp for the purpose of reducing power consumption or extending the life. Various light source devices using a chip as a light source have been proposed. For example, a light source device (ultraviolet curing device) using an LED chip that emits ultraviolet rays (ultraviolet LED chip) has been proposed, and such a light source device is an ultraviolet curable material that is cured by receiving ultraviolet rays, for example, It is used in a printing system that cures ultraviolet curable ink (also referred to as ink).

As this type of light source device, a plurality of (for example, several tens of) LED chips are mounted on a single support substrate so as to obtain the same amount of light as a conventional light source device using a discharge lamp or the like. Has been proposed (see, for example, Patent Document 1).
JP 2000-31546 A

  Here, when the LED chip is energized to emit light, the LED chip itself naturally generates heat. At this time, there is no problem if the number of LED chips is small, but in the case where several tens of LED chips are mounted on a single support substrate as in the light source device, the amount of heat generated by the LED chips increases significantly. . And since the luminous efficiency of an LED chip has a negative temperature coefficient, if the emitted-heat amount increases, the luminous efficiency of an LED chip will fall.

  Therefore, the light source device as described above is used in a state where the support substrate is thermally coupled to cooling means (for example, a cooling device such as a heat pipe) disposed on the opposite side of the support substrate from the LED chip side. Often done.

  If the cooling means as described above is used, the heat generated by the LED chip can be absorbed by the cooling means, so that the light emission efficiency of the LED chip of the light source device can be improved. However, as the amount of heat generation increases, it becomes necessary to use a high-performance cooling means, and the operation cost of the light source device increases. Therefore, there is a demand for improving the cooling efficiency of the light source device itself.

  Here, in order to improve the cooling efficiency of the light source device, it is conceivable to reduce the distance between the LED chip and the cooling means by reducing the thickness of the support substrate, but if the thickness of the support substrate is reduced, Naturally, the strength (mechanical strength) of the support substrate becomes weak, and when the light source device is attached to the cooling means, another problem that the support substrate is damaged may occur.

  The present invention has been made in view of the above points, and an object thereof is to provide a light source device capable of improving cooling efficiency while suppressing a decrease in strength of a support substrate.

  In order to solve the above problems, in the invention of claim 1, a cooling device including a support substrate and a plurality of LED chips mounted on the support substrate, and disposed on the opposite side of the support substrate from the LED chip side. The light source device is used in a state where the support substrate is thermally coupled to the means, and the support substrate has a base sheet in which the LED chip is arranged on one surface in the thickness direction and an opening for exposing the LED chip. And a frame that is joined to the one surface of the base sheet and reinforces the base sheet.

  According to the first aspect of the present invention, the support substrate has a base sheet in which the LED chip is arranged on one surface in the thickness direction, and an opening that penetrates in the thickness direction. The entire surface of the one surface of the base sheet is formed from the opening. Cooling disposed on the side opposite to the LED chip side of the support substrate, which is composed of a frame that is joined to the one surface so as to cover the LED chip so as to be exposed and reinforces the strength (mechanical strength) of the base sheet. The heat generated by the LED chip is reduced by reducing the thickness of the base sheet of the support substrate and increasing the thermal conductivity (thermal conductivity) of the base sheet. Supports because the base sheet is reinforced by the frame even when the thickness of the base sheet is reduced, because it is easy to be transmitted to the cooling means and cooling efficiency can be improved. The reduction in strength of the plate (mechanical strength) can be suppressed.

  According to a second aspect of the invention, in the first aspect of the invention, the base sheet has a mirror finish on the other surface.

  According to the invention of claim 2, since the adhesion between the other surface of the base sheet and other members such as cooling means can be improved, the thermal conductivity between the base sheet and the other members is improved, and the cooling efficiency is improved. .

  The invention of claim 3 is characterized in that, in the invention of claim 1 or 2, the base sheet is an insulating sheet.

  According to the invention of claim 3, unlike the case where the base sheet is made of a metal material such as copper, an accident such as an electric shock can be prevented.

  The invention of claim 4 is characterized in that, in the invention of claim 3, AlN is used as the material of the insulating sheet.

  According to the invention of claim 4, since AlN has a relatively high thermal conductivity among the insulating materials, the cooling efficiency can be improved.

  The invention of claim 5 is characterized in that, in the invention of any one of claims 1 to 4, the opening of the frame is formed in a shape in which a plurality of LED chips are arranged inside.

  According to the invention of claim 5, the shape of the frame can be simplified as compared with the case where the opening and the LED chip correspond one-to-one.

  The present invention has an effect that cooling efficiency can be improved while suppressing a decrease in strength of the support substrate.

  As shown in FIGS. 1A and 1B, a light source device 1 according to an embodiment of the present invention includes a support substrate 2 and a plurality (16 in the illustrated example) of LED chips 3 mounted on the support substrate 2. It has. As shown in FIGS. 1A and 2, the light source device 1 has a support substrate on the cooling means 4 disposed on the opposite side of the support substrate 2 from the LED chip side (the lower surface side in FIG. 1A). 2 is used in a thermally coupled state.

  The LED chip 3 is, for example, an ultraviolet LED chip having a peak wavelength in the ultraviolet region and capable of flip chip mounting. However, this is merely an example, and is not intended to limit the LED chip 3 to the ultraviolet LED chip.

  As illustrated in FIG. 1A, the support substrate 2 includes a base sheet 20 and a frame 21 that is bonded to the base sheet 20 and reinforces the base sheet 20.

  The base sheet 20 is, for example, a rectangular insulating sheet, and its material is AlN (aluminum nitride). On one surface side of the base sheet 20 in the thickness direction, for example, as shown in FIG. 1B, 16 LED chips 3 are bonded in a 4 × 4 matrix (4 × 4 matrix). On the other hand, the other surface in the thickness direction of the base sheet 10 (the lower surface in FIG. 1A) is mirror-finished (mirror finishing), thereby improving the flatness of the other surface of the base sheet 20 and other members. In this embodiment, the adhesion with the cooling means 4 is improved.

  For example, the frame 21 is formed in a rectangular plate shape having an outer size larger than the outer size of the base sheet 20, and the thickness thereof is set to be sufficiently larger than the thickness of the base sheet 20. When a material having a higher mechanical strength than the material of the base sheet 20 is used as the material of the frame 21, the thickness of the frame 21 does not necessarily need to be greater than the thickness of the base sheet 20, and a desired machine What is necessary is just to set to the thickness which can obtain a mechanical strength.

  The frame 21 is formed with an opening 21a that penetrates the frame 21 in the thickness direction (vertical direction in FIG. 1A). The opening 21a is formed in such a manner that all of a plurality (16 in the illustrated example) of LED chips 3 arranged on the base sheet 20 are arranged inside. In addition, as shown in FIG.1 (b), although the opening shape in the surface orthogonal to the thickness direction of the flame | frame 21 is a square shape, the opening part 21a is not the meaning limited to this, For example, circular shape It may be. A wiring pattern 22 is formed on the side of the frame 21 opposite to the base sheet 20 side (the upper surface side in FIG. 1A). The wiring pattern 22 has an electric path (not shown) for supplying power to the LED chip 3 from an external power supply device (not shown), and an electrode pad 22a.

  Such a frame 21 is bonded to the one surface of the base sheet 20 in such a manner that the LED chip 3 is exposed from the opening 21a, whereby the support substrate 2 having the shape shown in FIGS. 1A and 1B is obtained. . Thereafter, the electrode pad 22a provided on the frame 21 and the electrode (not shown) of the LED chip 3 are electrically connected by the bonding wire W. Therefore, in the light source device 1 of the present embodiment, the LED chip 3 is mounted on the support substrate 2 by wire bonding. 1A and 1B, only some of the bonding wires W are illustrated, and in FIG. 2, the bonding wires W and the conductive pattern 22 are omitted.

  Next, the cooling means 4 used for cooling the light source device 1 will be described. The cooling means 4 includes, for example, a cooling pipe 40 formed in a rectangular tube shape with a metal material (for example, aluminum having a high thermal conductivity among metal materials), and a flow path including an internal space of the cooling pipe 40. This is a so-called water-cooling type cooling apparatus provided with a pump (not shown) for flowing a heating medium such as water (also called a heating medium) (not shown) in 40a. The cooling means 4 may be an air-cooled cooling device using air as the heat medium. In this case, a fan is used instead of the pump. The heat medium is not limited to water or air, but may be other fluids.

  In the light source device 1 described above, as shown in FIG. 1A, the other surface of the base sheet 20 is brought into contact with one side surface of the cooling pipe 40 of the cooling means 4 (upper side surface in FIG. 1A). In this manner, it is attached to the cooling means 4 for use. FIG. 2 shows an example in which a plurality of light source devices 1 are attached to one cooling means 4.

  The heat generated in the LED chip 3 due to the use of the light source device 1 is transmitted to the base sheet 20 and then to the heat medium flowing through the flow path 40a via the cooling pipe 40, and the heat medium whose temperature has risen flows. Cooling while flowing through the path 40a. In this way, the LED chip 3 of the light source device 1 is cooled by the cooling means 4.

  According to the light source device 1 of the present embodiment described above, the thickness direction on the opposite side to the LED chip 3 side of the support substrate 2 (the thickness direction opposite to the one surface side in the thickness direction on the base sheet 20 where the LED chip 3 is disposed). Since the support substrate 2 is used in a state where it is thermally coupled to the cooling means 4 disposed on the other surface side, the thickness of the base sheet 20 of the support substrate 2 is reduced, so that the heat conduction of the base sheet 2 is achieved. The cooling efficiency can be improved by increasing the rate (thermal conductivity).

  Further, since the frame 21 that reinforces the mechanical strength of the base sheet 20 is joined to the one surface of the base sheet 20, the mechanical strength of the support substrate 2 can be increased even when the thickness of the base sheet 20 is reduced. It can be improved. In addition, when the light source device 1 is attached to the cooling means 4, it is possible to prevent the base sheet 20 from being damaged or the base sheet 20 from being deformed due to its thinness. Attachment to the means 4 can be easily performed.

  In addition, since the other surface of the base sheet 20 is mirror-finished, it is possible to improve the adhesion between the other surface of the base sheet 20 and the cooling means 4 (cooling pipe 40) which is another member. Efficiency can be improved. Furthermore, since the base sheet 20 is an insulating sheet, unlike the case where the base sheet 20 is made of a metal material such as copper, an accident such as an electric shock can be prevented. Moreover, since AlN having a relatively high thermal conductivity is used as the material of the insulating sheet, the cooling efficiency can be improved.

  Furthermore, since the opening 21a of the frame 21 is formed in a shape in which a plurality of LED chips 3 are arranged on the inside, the opening 21a is formed in a form in which one LED chip 3 is arranged on the inside ( Compared to the case where the opening 21a and the LED chip 3 correspond one-to-one), the shape of the frame 21 can be simplified, and the manufacturing cost can be reduced.

  In the light source device 1 of the present embodiment, the LED chip 3 is mounted on the support substrate 2 by wire bonding. For example, a wiring pattern for the LED chip 3 (see FIG. (Not shown) may be formed, and the LED chip 3 may be flip-chip mounted on the support substrate 2.

  By the way, the cooling means 4 is not limited to the above-described water-cooled or air-cooled cooling device, but may be other cooling devices. For example, as the cooling means 4, a Peltier element (also called a Peltier element), which is a plate-like semiconductor element that utilizes a heat transfer from one metal to the other (Peltier effect) when an electric current is passed through a joint between two kinds of metals. Or a heat pipe (thermo siphon) that is a heat transfer device that encloses a working fluid (for example, water) in a sealed container and transfers heat by evaporation and condensation of the working fluid. It is also possible to use a thermotube). There are two types of heat pipes, one that uses gravity and the other that uses capillary action due to wicks, to return the condensed working liquid after evaporating and moving to gas to its original position. Which is used may be appropriately selected according to the usage pattern of the light source device 1. For example, when the light source device 1 is used with the one surface of the base member 11 facing downward, a heat pipe using gravity may be used.

  In the example shown in FIGS. 1A and 2, the light source device 1 is directly attached to the cooling unit 4. For example, a material having a higher thermal conductivity than the material of the base sheet 20 (for example, In the present embodiment, a heat transfer plate (not shown) made of copper or the like having a higher thermal conductivity than AlN may be interposed between the light source device 1 and the cooling means 4. According to such a heat transfer plate, the heat of the base sheet 20 can be diffused and transmitted to the cooling means 4, so that the cooling efficiency can be improved. By the way, when using such a heat transfer plate, the plurality of light source devices 1 may be attached to the heat transfer plate, and then the heat transfer plate may be attached to the cooling means 4. The light source device 1 can be easily attached to the cooling means 4.

  Further, the support substrate 2 of the light source device 1 of the present embodiment is formed by bonding one base sheet 20 to the frame 21, but the support substrate 2 is formed by bonding a plurality of base sheets 20 to the frame 21. It may be.

The light source device of one Embodiment of this invention is shown, (a) is the schematic sectional drawing which abbreviate | omitted a part, (b) is the front view which abbreviate | omitted a part. It is the perspective view which fractured | ruptured a part of light source device same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source device 2 Support substrate 3 LED chip 4 Cooling means 20 Base sheet 21 Frame 21a Opening part

Claims (5)

A support substrate and a plurality of LED chips mounted on the support substrate are used, and the support substrate is used in a state where the support substrate is thermally coupled to a cooling unit disposed on the opposite side of the support substrate from the LED chip side. A light source device,
The support substrate is composed of a base sheet in which the LED chip is arranged on one surface in the thickness direction, and a frame that has an opening for exposing the LED chip and is bonded to the one surface of the base sheet to reinforce the base sheet. A light source device characterized by the above.   2. The light source device according to claim 1, wherein the other surface of the base sheet is mirror-finished.   The light source device according to claim 1, wherein the base sheet is an insulating sheet.   The light source device according to claim 3, wherein AlN is used as a material of the insulating sheet.   5. The light source device according to claim 1, wherein the opening of the frame is formed in a shape in which a plurality of LED chips are arranged inside.

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