JP2009130234A - Circuit board, and led module having the circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board having high reflection function in the visible light range, and to provide an LED module. <P>SOLUTION: A circuit board comprises a base material, made of a metal foil; an insulation layer formed on one or both surfaces of the base material; and a circuit formed on an exposed surface of the insulation layer by using a metal foil. The circuit is formed with copper foil, and a nickel layer or an aluminum layer is laminated on a portion or the whole copper foil. In another embodiment, the circuit is formed with aluminum foil, and a nickel layer or a copper layer is laminated on a portion or the whole of the aluminum foil. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a circuit board and an LED module for a direct backlight using an LED (Light Emitting Diode) as a light source, and more specifically, a high reflectivity alternative to a light reflection sheet and a high reflection coating film. The present invention relates to a highly reflective circuit board having a metal foil.

Conventionally, liquid crystal display devices have been used in various fields, and in particular, have been used in many fields in the electronic industry such as personal computers and televisions. Among these liquid crystal display devices, particularly those that employ a direct type backlight system, a backlight is disposed on the back of the liquid crystal panel, and the backlight uses the light emitted from the light source as a light guide plate. Incident light is transmitted, and the propagated light is emitted from the front surface side of the light guide plate through a prism sheet or the like, so that the entire back surface of the liquid crystal panel is irradiated. As the light source of the backlight, many use a small fluorescent tube or LED called CCFL (Cold Cathode Fluorescent Lamp). However, in recent years, due to environmental considerations, backlights using LEDs as light sources are spreading instead of CCFLs using mercury.

In addition, it is desired to further increase the area of a liquid crystal display device for television, and for this purpose, a large amount of light is required. Therefore, it is necessary to supply as much light as possible to the liquid crystal part. For this reason, in order to maximize the amount of light supplied from the backlight, it is necessary to effectively use not only the emitted light from the LED but also the reflected light. In order to effectively use the reflected light, it is common to use a light reflecting sheet.

Also, recently, a coating that is coated with a resin containing inorganic filler titanate dioxide, barium sulfate, zinc oxide, etc., which has a high reflectance in the visible light region, and attempts to obtain high reflected light without using a light reflecting sheet. Has also been proposed.

A method for obtaining higher reflected light by plating silver, which is a highly reflective metal, on the circuit portion has been conventionally used.
JP 2006-310014 A JP-A-8-23146

Conventionally, a printed circuit board for mounting an LED package for a direct type backlight has no light reflecting function. Therefore, when used as a printed circuit board for a backlight, it is necessary to attach a light reflecting sheet after mounting the LED package. there were. For this reason, there has been a problem that the number of man-hours and necessary members at the time of manufacture are complicated and handling is complicated in the manufacturing process, which is inconvenient.

Moreover, since the method of coating a coating film having a high reflectance is also strongly influenced by the reflectance of the ground (insulating layer and copper circuit foil), a satisfactory reflectance has not been obtained. Therefore, in order to reduce the influence of the base, it has been proposed to increase the film thickness. However, since the material uses an inorganic filler having a high reflectance, the curability of the coating film significantly decreases as the thickness increases. There was a problem in the process.

The method of plating silver, which is a metal having a high reflectivity, has a problem that the ion reliability is low when used under high temperature and high humidity (DC voltage application), and the insulation reliability is lowered.

Conventionally, when an electrolytic copper foil with high adhesion reliability is used on the bonding side of the insulating layer, conductor loss due to surface roughness is generated and cannot be used in a high frequency band. Further, with a rolled copper foil having a small surface roughness, sufficient adhesion reliability cannot be obtained, and this also has a problem in use.

An object of the present invention is to provide a completely new circuit board and LED module that can solve the above-described problems.

That is, the present invention provides a circuit board having a base made of a metal foil, an insulating layer formed on one or both surfaces of the base, and a circuit formed of the metal foil on the exposed surface of the insulating layer. The circuit board is made of a copper foil, and a nickel layer or an aluminum layer is laminated on a part or the whole of the copper foil.

Another invention according to the present application includes a base material made of a metal foil, an insulating layer formed on one or both surfaces of the base material, and a circuit formed of the metal foil on the exposed surface of the insulating layer. A circuit board, wherein the circuit is made of an aluminum foil, and a nickel layer or a copper layer is laminated on a part or the whole of the aluminum foil.

In the present invention, the insulating layer is preferably white, and preferably has a white film formed on the insulating layer and the circuit. Moreover, it is preferable that the reflectances of visible light at 450 nm, 555 nm, and 660 nm are all 80% or more in the circuit board according to the present invention.

The white pigment of the insulating layer preferably contains one or both of zinc oxide and rutile type titanate, and the surface of the white pigment is either “aluminum hydroxide” or “aluminum hydroxide and silicon dioxide”. It is preferable that the coating is applied.

The thermal conductivity of the insulating layer is preferably 0.5 W / mK or more and 4.0 W / mK or less, and the thickness of the base material made of metal foil is preferably 18 μm or more and 4.0 mm or less.

The substrate made of metal foil is preferably a kind of material selected from aluminum, copper, and iron, and the white film preferably contains rutile-type titanate or zinc oxide as a white pigment. . It is also preferable that this white pigment is coated with aluminum oxide or “aluminum hydroxide and silicon dioxide”.

Moreover, in another invention, it is an LED module which has these circuit boards.

The circuit board of the present invention can effectively use reflected light only with the circuit board without attaching a light reflecting sheet after LED mounting. In other words, in addition to the function of the conventional printed circuit board for mounting electronic components, the circuit board has a new function of light reflection function. For example, when the circuit board of the present invention having a light reflection function is used as a printed circuit board for a direct type backlight using an LED, a white coating film having a high reflectance on the circuit board is used as a light reflection sheet. Since it suffices to use it, it is not necessary to use an expensive light reflecting sheet, and the number of man-hours and necessary members at the time of manufacturing the backlight can be reduced, leading to cost reduction.

The circuit board of the present invention realizes high reflectivity at low cost by using aluminum or nickel instead of silver having high reflectivity used conventionally. Silver is a material that easily generates ion migration because of its strong ionization tendency. However, in the present invention, the occurrence of ion migration can be suppressed, leading to improvement in insulation reliability.

Since the LED module of the present invention uses the above-described circuit board, the characteristics of the circuit board are shown, and the reflectance, thermal conductivity, electrical characteristics, and productivity are excellent. The module can be easily obtained.

Hereinafter, the present invention will be described with reference to the drawings.

FIG. 1 is an example of a circuit board according to the present invention. In the circuit board of the present invention, a white film 5 having a high reflectivity is formed on a circuit board 6 composed of a substrate 1, an insulating layer 2, a circuit foil 3 (copper), and a circuit foil 4 (aluminum or nickel). A plurality of LEDs 9 are joined and mounted by solder joints 7 or the like. In the present invention, the circuit foil 4 (aluminum or nickel) and the white film 5 on the circuit foil are characterized by having a high reflectance, which is 80% or more with respect to a visible light region of 400 nm to 800 nm. In a preferred embodiment, the reflectance is preferably 80% or more for 460 nm (blue), 525 nm (red), and 620 nm (red).

The circuit board of the present invention has the above-described configuration, and the thermal conductivity of the insulating layer is 1.0 W / mK to 16.0 W / mK, and between the conductor circuit and the base material (made of metal foil). It has high heat dissipation and withstand voltage characteristics such that the withstand voltage is 1.5 kV or more, preferably 2 kV or more, and the heat generated from the LED light source is efficiently dissipated to the back side of the circuit board and further dissipated to the outside. Thus, the heat storage of the LED package mounting circuit board can be reduced, and the temperature rise of the LED can be reduced, thereby suppressing a decrease in the luminous efficiency of the LED. For this reason, a bright and long-life backlight is combined with the effect of the high-reflectance white film 5 in which a synergistic effect of the circuit foil 4 (aluminum or nickel) having a light reflecting function and the circuit foil 4 is expected. Can be provided.

In the present invention, as the substrate 1, copper and copper alloy, aluminum and aluminum alloy, iron and stainless steel having good thermal conductivity can be used. Moreover, as thickness of the base material 1, the thing of 18 micrometers or more and 4.0 mm or less is preferable. This is because if the thickness of the substrate 1 is too thin, the rigidity of the circuit board is lowered, so that it is not suitable for actual use. If the thickness is too thick, it tends to be unfavorable for downsizing and thinning.

In the present invention, the thickness of the insulating layer is preferably 50 μm or more and 400 μm or less, more preferably 80 μm or more and 200 μm or less. If the insulating layer is thin, the electrical insulating property is lowered, and if it is too thick, sufficient heat dissipation characteristics cannot be obtained.

As the insulating layer, a thermosetting resin is usually used. As the thermosetting resin, an epoxy resin, a phenol resin, a silicone resin, an acrylic resin, or the like can be used. Among them, the main component is a bifunctional epoxy resin and a polyaddition type curing agent, which will be described later, which are excellent in bonding strength and insulation between the base material 1 and the circuit foil (copper) 3 in the cured state while containing an inorganic filler. These are preferred. As the polyaddition type curing agent, acid anhydrides and phenols excellent in mechanical and electrical properties are preferable, and the active hydrogen equivalent is 0.8 equivalent to the epoxy equivalent of the epoxy resin contained in the thermosetting resin. It is preferable to add so as to be 1 to 1 times in order to ensure the mechanical and electrical properties of the insulating layer.

As epoxy resins, bifunctional epoxy resins such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, resorcinol diglycidyl ether, hexahydrobisphenol A diglycidyl ether, polypropylene glycol diglycidyl ether, nero Those using pentyl glycol diglycidyl ether, phthalic acid diglycidyl ester, dimer acid diglycidyl ester or the like are desirable.

Examples of polyaddition type curing agents include phthalic anhydrides such as acid anhydrides, tetrahydromethyl phthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, methyl nadic anhydride, phenolic phenol novolac resins and orthocresol novolac resins. Bisphenol A type novolac resin is desirable.

Further, a curing catalyst may be added to accelerate the curing reaction between the epoxy resin and the polyaddition type curing agent. As the curing catalyst, an imidazole type is preferable, and 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-methyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4. -Methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 2,3-dihydro-1H-pyrrolo [1,2-a] benzimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2 , 4-Diamino-6- [2′-methylimidazolyl (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-undecylimidazolyl (1 ′)]-ethyl-s-triazine, 1-cyanomethyl-2-methylimidazole It is preferred. The amount added may be arbitrarily changed in order to obtain a desired curing rate.

The chloride ion concentration in the thermosetting resin constituting the insulating layer 2 is preferably 1000 ppm or less, and more preferably 500 ppm or less. If the chloride ion concentration in the curable resin composition is too low, the migration of ionic impurities may occur at high temperatures and under DC voltage, and the electrical insulation property may tend to be reduced.

The inorganic filler contained in the insulating layer 2 is preferably an electrically insulating and heat conductive material, and for example, silica, alumina, aluminum nitride, silicon nitride, boron nitride or the like is used. The content of the inorganic filler in the insulating layer 2 is preferably 30% by volume to 80% by volume, and more preferably 50% by volume to 75% by volume. As for the particle size of the inorganic filler, it is preferable that the average particle size contains two types having an average particle size of 0.6 μm to 2.4 μm and 5 μm to 20 μm. By mixing coarse particles having a large average particle diameter and fine particles having a small average particle diameter, it becomes possible to achieve higher filling than when each of them is used alone, and good thermal conductivity can be obtained. Moreover, there are particle shapes such as crushed, spherical and scale-like. If the inorganic filler content is too low, it tends to be difficult to obtain the necessary thermal conductivity as a circuit board for a backlight using an LED package. Tends to be difficult, and problems of mechanical properties and electrical properties tend to occur. Moreover, it is preferable that the sodium ion concentration in an inorganic filler is 500 ppm or less, and it is more preferable that it is 100 ppm or less. When the sodium ion concentration in the inorganic filler increases, the migration of ionic impurities may occur at high temperatures and under DC voltage, and the electrical insulation properties may tend to be reduced.

When a white pigment is used for the insulating layer 2, zinc oxide and / or titanium dioxide can be suitably used. In titanium dioxide, the rutile type is preferable from the viewpoint of stability. Furthermore, the surface of the pigment is more preferably coated with aluminum hydroxide, or aluminum hydroxide and silicon dioxide. The white pigment is preferably contained in an amount of 1 to 30 parts by weight. If the amount is too small, the reflectance improvement effect cannot be expected. When the amount is too large, the increase in the resin viscosity is large, and it becomes easy to enclose defects at the time of coating, and the electric insulation property tends to be lowered.

The insulating layer 2 can be multilayered. In this case, the white pigment may be contained in a layer corresponding to the outermost layer of the circuitized surface.

The thickness of the circuit foil 3 is preferably 5 μm or more and 300 μm or less, and if it is too thin, the function as a circuit cannot be sufficiently achieved, and if it is thick, it can be used for large current applications, but if it is too thick, it is cost-effective. Is not preferable. As the circuit foil 3, it is possible to use copper or aluminum and an alloy containing them.

The thickness of the circuit foil 4 is preferably 0.1 μm or more and 400 μm or less. When copper is used as the circuit foil 3, aluminum or nickel can be suitably used as the circuit foil 4, and it has a function of a coating layer for obtaining a high reflectance. The effect tends to be difficult to obtain, and if it is too thick, it is not preferable because of cost effectiveness. Further, when aluminum is used as the circuit foil 3, copper or nickel can be preferably used as the circuit foil 4, which has the effect of improving the solder wettability when mounting components on the circuit. If it is thin, sufficient solder wettability tends not to be improved, and if it is too thick, it is not preferable from the viewpoint of cost effectiveness.

As a method of providing the circuit foil 4 on the circuit foil 3, it is possible to provide a pre-laminated foil on the insulating layer, or to provide the circuit foil 4 separately after the circuit foil 3 is provided on the insulating layer. Is possible. There are no particular restrictions on the method of laminating these, and known methods such as laminating by rolling, plating, and vapor deposition can be used, and multiple metal foil layers can be provided between the circuit foil 3 and the circuit foil 4. Is possible.

The white film 5 has a reflectance of 70% or more with respect to a visible light region of 400 to 800 nm, and in a more preferred embodiment, 70% or more with respect to 460 nm (blue), 525 nm (red), and 620 nm (red). It is preferable to have a reflectance of. As such a material, a white solder resist can be preferably used.

As the white solder resist, a thermosetting white solder resist, an ultraviolet curable white solder resist, an ultraviolet / heat combined white solder resist, or the like can be used.

The white pigment contained in the white solder resist is preferably titanium dioxide, and more preferably a rutile type. Since the rutile type is excellent in stability, the photocatalytic action is weak, and deterioration of the resin component is suppressed as compared with those of other structures. The white pigment made of titanium dioxide is more preferably coated with silicon dioxide or aluminum hydroxide. Titanium dioxide that has been subjected to such a treatment can further suppress the photocatalytic action and suppress deterioration of the resin component. The content of titanium dioxide is preferably 30% by mass to 60% by mass in the white film. Titanium dioxide can be used alone or in combination with other white pigments typified by zinc oxide and barium sulfate.

The resin used for the solder resist is an epoxy resin in the case of a thermosetting white solder resist, an acrylic resin in the case of an ultraviolet curable white solder resist, and an epoxy resin and an acrylic resin in the case of an ultraviolet / heat combined white solder resist. The combined use is desirable.

FIG. 2 is an example of the circuit board of the present invention. In the circuit board of the present invention, a white film 5 having a high reflectivity is formed on a circuit board 6 composed of a substrate 1, an insulating layer 2, a circuit foil 3 (aluminum), and a circuit foil 4 (copper or nickel). A plurality of LEDs 9 are joined and mounted by solder joints 7 or the like. In the present invention, the circuit foil 3 (aluminum) and the white film 5 on the circuit foil have a high reflectance, and the reflectance is 80% or more in the visible light region of 400 nm to 800 nm. In a more preferred embodiment, it is preferable to have a reflectance of 80% or more for 460 nm (blue), 525 nm (red), and 620 nm (red).

The circuit foil 3 (aluminum) preferably has a surface 10-point average roughness (Rz) of 1.0 μm or less. It is preferable to reduce the value of the 10-point average roughness (Rz) because the influence of the conductor loss is small at the time of high frequency correspondence and sufficient adhesive strength with the insulating layer can be secured.

FIG. 3 is an example of the circuit board of the present invention. In the circuit board of the present invention, a circuit board 6 comprising a base material 1, an insulating layer 2, a circuit foil 3 (aluminum), and a circuit foil 4 (copper or nickel) is shown, and a plurality of LEDs 9 are joined by soldering. It is jointly mounted by the part 7 or the like. In the present invention, the circuit foil 3 (aluminum) is characterized by having a high reflectance, and has a reflectance of 80% or more in a visible light region of 400 nm to 800 nm, and in a more preferred embodiment, 460 nm. It is preferable to have a reflectance of 80% or more for (blue), 525 nm (red), and 620 nm (red).

FIG. 4 is an example of a circuit board according to the present invention. In the circuit board of the present invention, a circuit board 6 comprising a base material 1, an insulating layer 2, a circuit foil 3 (copper), and a circuit foil 4 (aluminum or nickel) is shown. It is jointly mounted by the part 7 or the like. In the present invention, the circuit foil 4 (aluminum or nickel) is characterized by having a high reflectance, and a reflectance of 80% or more with respect to a visible light region of 400 to 800 nm, and in a more preferred embodiment It is preferable to have a reflectance of 80% or more for 460 nm (blue), 525 nm (red), and 620 nm (red).

(Example 1)
First, as a coarse powder of inorganic filler, crystalline silicon dioxide (manufactured by Tatsumori Co., Ltd., A-1; maximum particle size is 96 μm (100 μm or less)) and 60 μ% (50 mass% or more) of 5 μm to 50 μm particles are contained. , 55 parts by mass of an average particle size of 12 μm, and crystalline silicon dioxide as a fine powder of an inorganic filler (manufactured by Tatsumori Co., Ltd., 5X; 0.7 μm or less is 70% by mass, 2.0 μm or more is 70% by mass, average particle 14 parts by mass of a diameter of 1.2 μm) was mixed to obtain a raw material inorganic filler.

5 parts by weight of titanate (Ishihara Sangyo Co., Ltd., CP-50: average particle size 300 nm) whose surface was treated with aluminum hydroxide and silicon dioxide was added as a white inorganic pigment.

20 parts by mass of a bisphenol A type liquid epoxy resin (Japan Epoxy Resin, EP828) and 1 part by mass of a silane coupling agent (Nihon Unicar, A-187) were added and kneaded by a kneader at a heating temperature of 90 ° C. While mixing the raw material inorganic filler, the inorganic pigment, and the additive, a resin composition (a) for a circuit board was produced.

To 20 parts by mass of the bisphenol A type epoxy resin, 6 parts by mass of a phenol-based cured resin (Dainippon Ink Chemical Co., Ltd., TD-2131) was added as a curing agent to obtain a resin composition (b).

The resin composition (b) was applied onto an aluminum plate having a thickness of 1.5 mm so that the thickness after curing was 100 μm, and the resin composition was heated to 100 ° C. for 0.1 hour to be in a semi-cured state. A foil clad with 9 μm thick copper and 40 μm thick aluminum was laminated on the product (b), and further heated at 180 ° C. for 2 hours to complete the curing, and a substrate for a hybrid integrated circuit was produced.

As the white solder resist, heat and ultraviolet curable acrylic and epoxy resin combined system (manufactured by Yamaei Chemical Co., SSR-6300S) was applied to the hybrid integrated circuit board to obtain a circuit board. The results of these formulations are shown in Table 1.

Various characteristics of the obtained circuit board were examined as described later, and the results are shown in Table 2.

Dielectric strength: The periphery of copper foil and aluminum foil was etched as a measurement sample, and a circular portion having a diameter of 20 mm was left as a sample. Insulate specimens for withstand voltage before and after exposure to conditions of temperature 85 ° C, humidity 85% RH, DC 1000V, 1000 hours, and temperature 121 ° C, humidity 100% RH, 2 atm, 96 hours. It was immersed in oil, an AC voltage was applied between the copper foil and the aluminum plate at room temperature, and the measurement was performed based on JIS C 2110. TOS-8700 manufactured by Kikusui Electronics Co., Ltd. was used as the measuring instrument.

Insulation resistance value: The periphery of copper foil and aluminum foil was etched as a measurement sample, and the sample was left in a comb shape and an electrode shape based on JIS C6481. Insulation resistance values before and after exposure under conditions of temperature 85 ° C, humidity 85% RH, DC 1000V, 1000 hours, and before and after exposure to temperature 121 ° C, humidity 100% RH, 2 atm, 96 hours, DC at room temperature A voltage of 100 V was applied between the copper foil and the aluminum plate, and measurement was performed based on JIS C6481. R8340A manufactured by Advantest Co., Ltd. was used as the measuring instrument.

(Reflectance)
The produced circuit board was used as a measurement sample. As measurement locations, (1) between circuits (2) two locations on circuit foil (+ resist) were measured. The measuring instrument used was a spectrophotometer UV-2550 manufactured by Shimadzu Corporation.

(Example 2)
A circuit board was obtained in the same manner as in Example 1 except that the configuration of the circuit foil was changed. The results are shown in Table 2.

(Example 3)
A circuit board was obtained in the same manner as in Example 1 except that the white solder resist was not applied.

Example 4
A circuit board was obtained in the same manner as in Example 1 except that the addition amount of the white pigment was changed.

(Comparative Example 1)
A circuit board was obtained in the same manner as in Example 1 except that the circuit foil was only copper.

(Comparative Example 2)
A circuit board was obtained in the same manner as in Example 1 except that electrolytic silver plating was applied to copper as a circuit foil.

Since the circuit board of the present invention has a white coating film having a high reflectivity formed on the surface of the board on which the LED package is mounted, it has a light reflection function with a configuration similar to that of a normal printed circuit board. For this reason, the reflected light of the LED light source can be supplied to the liquid crystal part without using an expensive light reflecting sheet. Moreover, the man-hour at the time of liquid-crystal backlight manufacture can also be reduced, it is efficient and is industrially very useful as a circuit board for LED.

FIG. 1 is an explanatory view showing an example of a circuit board according to the present invention. FIG. 2 is an explanatory view showing an example of a circuit board according to the present invention. FIG. 3 is an explanatory view showing an example of a circuit board according to the present invention. FIG. 4 is an explanatory view showing an example of a circuit board according to the present invention.

Explanation of symbols

1 Base material 2 Insulating layer 3 Circuit foil 4 Circuit foil 5 White film (solder resist)
6 Circuit board 7 Solder joint 8 LED electrode terminal 9 LED

Claims (13)

A circuit board having a base made of metal foil, an insulating layer formed on one or both surfaces of the base, and a circuit formed of metal foil on the exposed surface of the insulating layer, the circuit Is a circuit board in which a nickel layer or an aluminum layer is laminated on a part or the whole of the copper foil. A circuit board having a base made of metal foil, an insulating layer formed on one or both surfaces of the base, and a circuit formed of metal foil on the exposed surface of the insulating layer, the circuit Is a circuit board in which a nickel layer or a copper layer is laminated on a part or the whole of the aluminum foil. The circuit board according to claim 1, wherein the insulating layer is white. The circuit board according to claim 1, further comprising a white film formed on the insulating layer and the circuit. The circuit board according to any one of claims 1 to 4, wherein the visible light has a reflectance of 450%, 555 nm, and 660 nm, respectively, of 80% or more. The circuit board according to any one of claims 3 to 5, wherein the white pigment of the insulating layer contains one or both of zinc oxide and rutile type titanate. The circuit board by which the surface of the white pigment of Claim 6 is coat | covered with either "aluminum hydroxide" or "aluminum hydroxide and silicon dioxide." The circuit board according to claim 1, wherein the insulating layer has a thermal conductivity of 0.5 W / mK or more and 4.0 W / mK or less. The circuit board according to any one of claims 1 to 8, wherein the thickness of the base material is 18 µm or more and 4.0 mm or less. The circuit board according to claim 1, wherein the base material is a kind of material selected from aluminum, copper, and iron. The circuit board according to claim 4, wherein the white film contains rutile type titanate or zinc oxide as a white pigment. A circuit board, wherein the white pigment according to claim 11 is coated with aluminum oxide or “aluminum hydroxide and silicon dioxide”. The LED module which has a circuit board as described in any one of Claims 1 thru | or 12.

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