CN102569598A

CN102569598A - Insulating substrate, method for manufacturing the substrate, optical module utilizing the substrate and liquid crystal display device utilizing the substrate

Info

Publication number: CN102569598A
Application number: CN2011102812113A
Authority: CN
Inventors: 堀田吉则
Original assignee: Fujifilm Corp
Current assignee: Fujifilm Corp
Priority date: 2010-09-30
Filing date: 2011-09-21
Publication date: 2012-07-11
Also published as: JP2012079748A; JP5416674B2; KR20120033997A

Abstract

An insulating substrate, a manufacturing method thereof, a light source module using the same, and a liquid crystal display apparatus are provided to reduce the number of inter-metallic compounds on an anodic oxide film which is formed by performing an anodic oxidation process, thereby improving insulation and transparent properties. An insulating substrate (1) comprises an aluminum substrate (2) and a through-hole (3). The front surface, the rear surface of the aluminum substrate, and the inner surface of the through hole are coated with an anodic oxide film (4). The purity of aluminum of the aluminum substrate has 99.90 mass percent or greater. The through hole is formed by penetrating the aluminum substrate in a thickness direction. An edge part of an opening part of the trough hole is melted by performing a melting process after a through-hole formation process.

Description

Insulating substrate, method of manufacturing the same, and light source module and liquid crystal display device using the same

Technical Field

The present invention relates to an insulating substrate used for a light emitting element, and more particularly, to an insulating substrate used for a light emitting diode (hereinafter, referred to as "LED"), a method for manufacturing the same, and a light source module and a liquid crystal display device using the same.

Background

In general, compared with fluorescent lamps, LEDs are said to have a power consumption of 1/100 and a lifetime of 40 times (40000 hours). Such a feature of power saving and long life is an important element for adopting an LED in a trend of attaching importance to the environment.

In particular, white LEDs have advantages of excellent color rendering properties and a simpler power supply circuit than fluorescent lamps, and thus have been expected to be used as light sources for illumination.

In recent years, white LEDs (30 to 150lm/W) having high luminous efficiency, which are required as illumination light sources, are on the market, and are superior to fluorescent lamps (20 to 110lm/W) in terms of light utilization efficiency in practical use.

As described above, the trend of applying white LEDs instead of fluorescent lamps is rapidly increasing, and the use of white LEDs as backlights of liquid crystal display devices and illumination light sources is increasing.

However, if a large amount of current flows through the LED chip to achieve high luminance, the amount of heat generated increases, which accelerates the aging of the wavelength conversion phosphor-supporting resin material over time, and as a result, sacrifices the feature of long life.

In fact, in the conventional LED, if the LED is driven for a long time or driven at a high current for increasing the light emission luminance, the LED chip significantly radiates heat to reach a high temperature state, which causes a problem of thermal degradation.

In order to solve such a problem, an insulating substrate in which the surface of an aluminum substrate is covered with an anodic oxide film has been proposed (for example, see patent documents 1 to 7), and since the anodic oxide film has an insulating property and the aluminum substrate has high thermal conductivity, it is expected that good heat dissipation is obtained.

Patent document 1 Japanese Kokai publication Sho 55-154564

Patent document 2 Japanese patent application laid-open No. 6-45515

Patent document 3 Japanese patent application laid-open No. 7-14938

Patent document 4 Japanese patent application laid-open No. Hei 11-504387

Patent document 5 Japanese patent application laid-open No. 2006-344978

Patent document 6 Japanese patent laid-open No. 2007-251176

Japanese patent application laid-open No. 2009-164583

The present inventors have studied the insulating substrates described in patent documents 1 to 7, and as a result, have found that, if a device (for example, an LED, a power chip, or the like) provided with a through hole and generating a large amount of heat is mounted and used, cracks or cracks are generated in the anodic oxide film near the opening of the through hole due to the difference in thermal expansion coefficient between the aluminum substrate as the base material of the insulating substrate and the anodic oxide film as the insulating layer, and the insulating property (withstand voltage) is deteriorated.

Disclosure of Invention

Therefore, an object of the present invention is to provide an insulating substrate which can maintain good heat dissipation and has excellent insulating properties even when used for LED applications, a method for manufacturing the insulating substrate, and a light source module and a liquid crystal display device using the insulating substrate.

The present inventors have conducted extensive studies to achieve the above object, and as a result, have found that the use of an insulating substrate (aluminum substrate with an anodic oxide film) having a through hole of a specific shape can achieve both insulation and heat dissipation properties even when used for LED applications, and have completed the present invention. That is, the present invention provides the following (1) to (10).

(1) An insulating substrate comprising an aluminum substrate and a through hole formed to penetrate the aluminum substrate in a thickness direction thereof, wherein at least a front surface and a back surface of the aluminum substrate and an inner wall surface of the through hole are covered with an anodic oxide film,

maximum diameter (d) of the through-hole₀) And minimum diameter (d)_r) The relationship with the thickness (t) of the insulating substrate satisfies the following formula (I).

0.5×t≤(d₀-d_r)＜t…(I)

(2) The insulating substrate according to the item (1), wherein the aluminum purity of the aluminum substrate is 99.90 mass% or more.

(3) The insulating substrate according to the above (1) or (2), which is used for LED applications.

(4) A method for manufacturing an insulating substrate, which is a method for manufacturing an insulating substrate according to any one of the above (1) to (3), comprising:

a through hole forming step of forming a through hole in the thickness direction of the aluminum substrate;

a dissolution treatment step of performing a dissolution treatment after the through hole forming step to dissolve at least an edge portion of the opening of the through hole; and

and an anodic oxidation treatment step of performing an anodic oxidation treatment after the dissolution treatment step to cover the front and back surfaces of the aluminum substrate and the inner wall surfaces of the through holes with an anodic oxide film.

(5) The method for manufacturing an insulating substrate according to the above (4), wherein the dissolving process is a photo-etching process.

(6) The method for manufacturing an insulating substrate according to the above (4) or (5), wherein a singulation step of singulating the aluminum substrate into a desired shape is provided after the through hole forming step and before the anodizing step.

(7) A light source module is provided with:

the insulating substrate according to any one of (1) to (3) above,

A light-emitting source mounted on the surface of the aluminum substrate, and

and a wiring layer provided on the back surface of the aluminum substrate and electrically connected to the light source through the through hole.

(8) The light source module according to the above (7), wherein the light emitting source is an LED.

(9) The light source module according to the above (7) or (8), which is used for a backlight assembly application.

(10) A liquid crystal display device includes: the light source module described in the above (9), and a liquid crystal display panel disposed on a light emitting side of the light source module.

As described below, according to the present invention, an insulating substrate excellent in insulating properties even when used for an LED application, a method for manufacturing the insulating substrate, and a light source module and a liquid crystal display device using the insulating substrate can be provided while maintaining good heat dissipation properties.

Drawings

Fig. 1 is a schematic cross-sectional view showing an example of a preferred embodiment of the insulating substrate of the present invention.

Fig. 2 is a schematic diagram for explaining the singulation step (route processing (ル - テイング processing)) in the method for manufacturing an insulating substrate according to the present invention.

Fig. 3 is a schematic cross-sectional view showing an example of a preferred embodiment of the light source module of the present invention.

Fig. 4 is a schematic cross-sectional view of another preferred embodiment of the light source module of the present invention.

Fig. 5 is a schematic cross-sectional view of another preferred embodiment of the light source module of the present invention.

Fig. 6 is a schematic cross-sectional view showing one embodiment of using the light source module of the present invention for a backlight unit.

Fig. 7 is a processing diagram showing dimensions and the like of the insulating substrate (before singulation) produced in the example.

Wherein,

1 insulating substrate of the invention

2 aluminum substrate

3 through hole

4 anodic oxide coating

21 chip

22 notch part

23 connecting part

31 insulating substrate of the invention

32 light emitting source

33 wiring layer

34 aluminum base material

35 through hole

36 anodic oxide coating

40 lead wire

41 recess

42 end face

43 lens

44 diffusion sheet

Detailed Description

[ insulating substrate ]

Next, the insulating substrate of the present invention will be described in detail.

The insulating substrate of the present invention comprises an aluminum substrate and a through hole formed to penetrate in the thickness direction of the aluminum substrate, wherein at least the front and back surfaces of the aluminum substrate and the inner wall surface of the through hole are covered with an anodic oxide film, and the maximum diameter (d) of the through hole₀) And minimum diameter (d)_r) The relation with the thickness (t) of the insulating substrate satisfies the formula (I).

Next, the structure of the insulating substrate of the present invention will be described with reference to fig. 1.

As shown in fig. 1, an insulating substrate 1 of the present invention includes an aluminum substrate 2 and a through hole 3, and at least the front and back surfaces (including end surfaces in fig. 1) of the aluminum substrate 2 and the inner wall surface of the through hole 3 are covered with an anodic oxide film 4.

The aluminum substrate, the through-hole, and the anodic oxide film constituting the insulating substrate of the present invention will be described in detail below.

< aluminum substrate >

As the aluminum substrate, an alloy plate containing aluminum as a main component and a trace amount of a different element may be used in addition to a pure aluminum substrate; a substrate on which high-purity aluminum is deposited on low-purity aluminum (e.g., a recycled material); a substrate having a surface of a silicon wafer, quartz, glass, or the like coated with high-purity aluminum by a method such as vapor deposition or sputtering; a resin substrate laminated with aluminum, and the like.

Here, examples of the different element that may be contained in the alloy sheet include silicon, iron, copper, manganese, magnesium, chromium, zinc, bismuth, nickel, titanium, and the like, and the content of the different element in the alloy is preferably 10 mass% or less.

The thickness of the aluminum substrate is not particularly limited, but is preferably 0.2 to 0.5mm from the viewpoint of reducing the back of the light source module of the present invention. Further, by processing the aluminum substrate into a desired shape, it is possible to flexibly cope with design changes and the like.

The higher the aluminum purity of the aluminum substrate, the better. Specifically, the aluminum purity is preferably 99.90 mass% or more, and more preferably 99.99 mass% or more.

When the aluminum purity is in the above range, impurities such as Si and Fe in the aluminum substrate are extremely small, and the number of intermetallic compounds remaining in an anodic oxide film formed by an anodic oxidation treatment described later is reduced, whereby the insulation property and the transparency are improved.

It is preferable that the surface of the aluminum substrate subjected to the anodization described later is subjected to degreasing treatment and mirror finishing treatment in advance.

The degreasing treatment is performed for the purpose of dissolving and removing organic components and the like such as dust, grease, resin and the like attached to the aluminum substrate using an acid, an alkali, an organic solvent and the like. In the degreasing treatment, a conventionally known degreasing agent can be used. Specifically, this can be performed, for example, by using various commercially available degreasing agents in a given method.

The mirror finishing treatment is performed to remove irregularities on the surface of the aluminum substrate, for example, embossed streaks generated when the aluminum substrate is rolled. The mirror finishing treatment is not particularly limited, and a known method can be used. Specifically, for example, mechanical polishing, chemical polishing, or electrolytic polishing can be used.

< Via hole >

The through hole is formed to penetrate in the thickness direction of the aluminum substrate before an anodic oxide film is formed by subjecting the aluminum substrate to an anodic oxidation treatment described later.

Thus, the inner wall surface of the through hole is also covered with the anodic oxide film.

The number of through holes to be formed is not particularly limited, and may be changed according to the embodiment.

In the present invention, the through-hole is a so-called bobbin shape in which the through-hole is thin in the vicinity of the central portion in the thickness direction of the insulating substrate of the present invention, specifically, the maximum diameter (d) of the through-hole₀) And minimum diameter (d)_r) The relationship with the thickness (t) of the insulating substrate satisfies the following formula (I).

0.5×t≤(d₀-d_r)＜t…(I)

Here, the so-called maximum diameter (d) of the through-hole₀) As shown in fig. 1, the diameter of the front and back surfaces of the insulating substrate 1 of the present invention, that is, the opening diameter of the through hole, is smaller when the opening diameter of the front surface is different from the opening diameter of the back surface.

In addition, the so-called minimum diameter (d) of the through-hole_r) As shown in fig. 1, the shortest diameter is formed in the vicinity of the center portion in the thickness direction of the insulating substrate 1 of the present invention.

The plate thickness (t) is also the thickness of the insulating substrate 1 of the present invention, as shown in fig. 1.

By providing the through hole satisfying the above formula (I), an insulating substrate having excellent insulating properties even when used for LED applications while maintaining good heat dissipation properties is formed.

This is considered to be because, if the through-holes are straight pipes, there are many locations where stress is concentrated due to the difference in thermal expansion coefficient between the aluminum substrate and the anodic oxide film, whereas if the through-holes are formed in a bobbin shape, the concentration of stress is relieved.

And, the maximum diameter (d) of the through-hole is set₀) And minimum diameter (d)_r) The difference (d) is defined by the relation of the plate thickness (t) of the insulating substrate, and is performed in consideration of a method for forming a wiring layer material (e.g., copper or the like) to be described later provided in the through hole in the light source module of the present invention (e.g., filling by electrolytic plating treatment), and if d₀-d_rIf the value of (A) is equal to or more than half of the thickness of the wiring board, the conduction reliability is sufficient, and if the value of (B) is less than the thickness of the wiring board, the waste of the wiring board material can be suppressed.

In the present invention, the inner wall surface of the through hole is preferably not provided with a curved surface having an angle of 90 degrees or less, and more preferably is formed of a curved surface or a curved surface and a smooth surface.

In the present invention, the shape of the through hole is not particularly limited as long as it satisfies the formula (I) and has a size (minimum diameter) in which necessary wiring can be incorporated, but is preferably 0.01 to 2mm, more preferably 0.05 to 1mm, and particularly preferably 0.1 to 0.8mm, in consideration of the size of the final chip and the more reliable formation of the wiring.

< anodic oxide coating >

The anodic oxide film is an oxide film covering the front and back surfaces of the aluminum substrate and the inner wall surfaces of the through-holes, and is formed by subjecting the aluminum substrate having the through-holes formed thereon to an anodic oxidation treatment described later.

The thickness of the anodic oxide film is preferably 5 to 75 μm, and more preferably 10 to 50 μm from the viewpoint of insulation.

[ method for producing insulating substrate ]

Next, a method for manufacturing an insulating substrate according to the present invention will be described in detail.

The method for manufacturing an insulating substrate of the present invention includes: a through hole forming step of forming a through hole in the thickness direction of the aluminum substrate; a dissolution treatment step of performing a dissolution treatment after the through hole forming step to dissolve at least an edge portion of the opening of the through hole; and an anodic oxidation treatment step of performing an anodic oxidation treatment after the dissolution treatment step to cover the front and back surfaces of the aluminum substrate and the inner wall surfaces of the through holes with an anodic oxide film.

Next, the through hole forming step, the dissolution treatment step, the anodization step, and other treatment steps that can be performed as needed will be described.

< Process for Forming Via hole >

The through-hole forming step is a step of forming the through-hole so as to penetrate in the thickness direction of the aluminum substrate.

In forming the through hole, a conventionally known method may be employed, and for example, drilling, punching with a die (hereinafter, simply referred to as "die processing"), wet etching, or the like, which will be described in detail below, may be employed.

In the formation of the through-holes, it is preferable that the through-holes have a diameter slightly larger than a target hole diameter in consideration of volume expansion of the aluminum substrate in an anodizing treatment step described later.

(drilling work)

The method of drilling is not particularly limited, and a conventionally known printed circuit board processing machine can be used for the drilling. For example, from the viewpoint of improving the work efficiency, it is preferable to use the method of processing by using the printed board outline processing machine described in paragraphs [0012] to [0015] of japanese patent application laid-open No. 2006-339318 and the drawings.

(mold processing)

The die processing is not particularly limited, and may be performed by a conventionally known method of punching by shearing. For example, the punching process described in paragraph [0043] and fig. 11] of jp 2010-182719 a is preferable because the generation of burrs around the opening of the through hole can be suppressed.

(Wet etching processing)

The wet etching is not particularly limited, and can be performed by a conventionally known etching method used for manufacturing an etching member such as a lead frame for a semiconductor device or a high-definition mask. For example, the metal thin plate processing method described in japanese patent laid-open No. 2003-277955 is preferable because the pitch of the through holes can be narrowed.

In the present invention, when the wet etching process is accompanied by a dissolution process (for example, an alkali etching process, a photolithography process, or the like), the edge portion of the opening of the through hole can be dissolved at the same time as the formation of the through hole, and therefore, it can be said that the through hole forming process and the dissolution process are simultaneously performed.

< dissolution treatment step >

The dissolution treatment step is a step of performing a dissolution treatment after the through-hole forming step to dissolve at least an edge portion of the opening of the through-hole.

Examples of the dissolution treatment include chemical polishing, electrolytic polishing, alkali etching, and photo etching, which are described in detail below.

(chemical polishing treatment)

Examples of the chemical polishing treatment include various methods described in "aluminum handbook", sixth edition, (japan) aluminum association, 2001, and p.164-165.

Further, the phosphoric acid-nitric acid method, Alupol I method, Alupol V method, Alcoa R5 method, H method, and the like can be suitably exemplified₃PO₄-CH₃COOH-Cu method, H₃PO₄-HNO₃-CH₃COOH method. Among them, phosphoric acid-nitric acid method, H is preferable₃PO₄-CH₃COOH-Cu method, H₃PO₄-HNO₃-CH₃COOH method.

(electrolytic polishing treatment)

Examples of suitable methods for the electrolytic polishing treatment include various methods described in "aluminum handbook", sixth edition, Japan aluminum Association, 2001, and p.164-165; the method described in the specification of U.S. Pat. No. 2708655; "surface technology for practical use", vol.33, No.3, 1986, and p.32-38.

(alkali etching treatment)

The alkali etching treatment is a treatment of contacting the aluminum substrate having the through-hole formed therein with an alkali solution.

Here, examples of the alkali used in the alkali solution include caustic alkali and alkali metal salts. Specifically, examples of the caustic alkali include caustic soda and caustic potash. Examples of the alkali metal salt include alkali metal silicates such as sodium metasilicate, sodium silicate, potassium metasilicate, and potassium silicate; alkali metal carbonates such as sodium carbonate and potassium carbonate; alkali metal aluminates such as sodium aluminate and potassium aluminate; alkali metal aldonates such as sodium gluconate and potassium gluconate; alkali metal hydrogen phosphates such as sodium dihydrogen phosphate, potassium hydrogen phosphate, sodium phosphate, and potassium phosphate. Among them, a solution of caustic alkali and a solution containing both caustic alkali and alkali metal aluminate are preferable in terms of high etching rate and low cost. Aqueous solutions of caustic soda are particularly preferred.

The concentration of the alkali solution may be determined according to the etching amount, but is preferably 1 to 50 mass%, more preferably 10 to 35 mass%. When aluminum ions are dissolved in the alkali solution, the concentration of aluminum ions is preferably 0.01 to 10 mass%, more preferably 3 to 8 mass%. The temperature of the alkali solution is preferably 20-90 ℃. The treatment time is preferably 1 to 120 seconds.

Examples of the method of contacting the aluminum plate with the alkali solution include a method of passing the aluminum plate through a bath to which the alkali solution is added, a method of immersing the aluminum plate in a bath to which the alkali solution is added, and a method of spraying the alkali solution onto the surface of the aluminum plate.

(photo-etching treatment)

The photo-etching treatment is a processing method using a photosensitive resin.

Specifically, the method comprises applying a photosensitive resin to the surface of the aluminum substrate on which the through-hole is formed, exposing the surface with light transmitted through a photographic original plate or directly exposing the surface with laser light or the like, developing and removing the photosensitive resin in the opening of the through-hole and the periphery thereof, and then chemically etching the opening.

By performing a chemical etching treatment, the through-hole can be formed into a linear axis shape when viewed from the cross section of the aluminum substrate.

< anodic Oxidation treatment step >

The anodizing treatment step is a step of covering the surface and the back surface of the aluminum substrate and the inner wall surface of the through hole with the anodic oxide film after the dissolving treatment step.

Here, the anodizing treatment is not particularly limited, and conventionally known anodizing treatments performed on an aluminum substrate may be used. When the anodic oxide film is required to have transparency in addition to insulation, it is preferable to combine the micropores present in the anodic oxide film in a regular array.

< singulation step >

The method for manufacturing an insulating substrate according to the present invention may further include a singulation step.

The step of singulating may be a step of singulating the aluminum substrate into a desired shape (for example, a shape in which a necessary machining allowance is added to a final product) after the through-hole forming step and before the anodizing step, and may be a step of singulating the aluminum substrate by a path machining (ル - テイング machining), a die machining, or the like, which will be described later. As shown in examples described later, the above-mentioned singulation step may be performed before the above-mentioned dissolution treatment step or after the above-mentioned dissolution treatment step as long as it is performed after the above-mentioned through hole forming step.

Next, a path processing as a suitable method will be described with reference to fig. 2.

The routing process is performed to obtain chips 21 (see fig. 2B) having 2 through holes 3 from a plate-shaped aluminum substrate 2 (see fig. 2 a) having the through holes 3 at predetermined positions.

In the routing process, a notch 22 penetrating the aluminum substrate 2 is formed around each chip 21 (see fig. 2B). At this time, it is preferable that the connecting portion 23 for connecting different chips 21 or connecting the chip 21 and the aluminum substrate 2 remains because the chip 21 is not cut out from the aluminum substrate 2 and falls to seventy-eight parts, and the chip 21 and the aluminum substrate 2 can be handled integrally.

After the routing process, the anodic oxidation treatment described above is performed (see fig. 2C), and the joint portion 23 is cut off, whereby the chip 21 as an insulating substrate can be obtained (see fig. 2D).

In addition, the size of the chips to be singulated in the above-mentioned singulation step needs to be in consideration of the size and shape of the final chip. For example, when a square type chip is assumed, the 1 side is preferably 0.1 to 50mm, more preferably 0.2 to 40mm, and particularly preferably 0.4 to 30mm from the viewpoint of compactness of the chip and workability. Particularly, when a reflective substrate for a main assembly (main package) is assumed, it is preferable to perform a routing process in a size of 3.2mm × 2.8mm, 1.6mm × 0.8mm, or the like, which is a current standard example of shape.

< other Process >

The method for manufacturing an insulating substrate according to the present invention preferably includes an etching step of performing etching treatment for removing burrs, processing oil, and the like on the aluminum substrate before the anodizing step (after the step in the case where the singulation step is provided).

The etching treatment may be performed using an acidic treatment liquid or an alkaline treatment liquid, and for example, phosphoric acid, a sodium hydroxide solution, or the like may be used. In this case, an organic solvent-based cleaning agent may be used together.

In the method for manufacturing an insulating substrate according to the present invention, it is preferable that the method for manufacturing an insulating substrate includes a water washing step of sufficiently washing the entire surface of the aluminum substrate for the purpose of ensuring uniformity during the anodization step after the etching step and before the anodization step.

After washing with water, it is preferable not to expose the entire surface of the aluminum substrate to air until the anodizing treatment, in order to suppress the formation of a natural oxide film and the adhesion of impurities in the air.

[ light Source Module ]

Next, the light source module of the present invention will be described in detail.

A light source module according to the present invention includes the insulating substrate according to the present invention, a light-emitting source mounted on a surface of the aluminum substrate, and a wiring layer provided on a back surface of the aluminum substrate and electrically connected to the light-emitting source through the through hole.

Next, the structure of the light source module of the present invention will be described with reference to fig. 3 to 6.

As shown in fig. 3, the light source module 30 of the present invention includes the insulating substrate 31 of the present invention, the light-emitting source 32, and the wiring layer 33.

As described above, the insulating substrate 31 of the present invention includes the aluminum substrate 34 and the through hole 35 formed to penetrate in the thickness direction of the aluminum substrate 34, and the surface and the back surface of the aluminum substrate 34 and the inner wall surface of the through hole 35 are covered with the anodic oxide film 36.

Although fig. 3 shows that the inside of the through hole 35 is entirely filled with a material for forming the wiring layer 33, the present invention is not particularly limited to the embodiment shown in fig. 3 as long as the light-emitting source 32 and the wiring layer 33 are electrically connected through the through hole 35, but a method (flip chip mounting) in which bump electrodes (not shown) are provided on the light-emitting source 32 and the wiring layer 33 and bonded thereto is preferable.

Fig. 4 to 5 are schematic cross-sectional views showing other preferred embodiments of the light source module according to the present invention.

As shown in fig. 4, the light-emitting source 32 may be mounted on the insulating substrate 31 of the present invention by wire bonding using a wire 40.

Further, as shown in fig. 5, it is preferable that the insulating substrate 31 of the present invention has a concave portion 41 on the surface thereof, and the light-emitting surface is provided in the concave portion 41 so as to have the same height as the main surface (reflective surface) of the anodized aluminum substrate 31 by providing the light-emitting source 32 in the concave portion 41.

As shown in fig. 6, it is preferable to further provide a lens 43 on the upper surface of the light-emitting source 32 for the reason that the luminance characteristics are improved.

Further, for the reason that the luminance characteristics are more excellent, it is preferable to further include a diffusion sheet 44 on the upper portion of the lens 43, and it is more preferable to further include a light guide plate 45 between the lens 43 and the diffusion sheet 44.

Next, materials, dimensions, forming methods, and the like will be described with respect to the light-emitting source, the wiring layer, and the like other than the insulating substrate of the present invention.

< light emitting source >

The light source module of the present invention may be provided with a light emitting chip alone, or may be a module including a light emitting chip, a heat radiator, a lead portion, and a module portion.

The light emitting chip is preferably an LED as a semiconductor element which generates light and heat when power is applied.

The light emitting chip is formed using a material such as an AlGaIn system, an AlGaInP system, an AlGaInPAs system, a GaN system used for electronic devices such as transistors, or the like, which is used for a red semiconductor laser element including a GaAlAs system or a high-density optical disk, which includes an active layer and a cladding layer covering the active layer.

In the method of mounting the light-emitting source on the surface of the film-attached aluminum substrate, the maximum temperature is preferably 220 to 350 ℃, more preferably 240 to 320 ℃, and particularly preferably 260 to 300 ℃ in the thermocompression bonding including solder reflow and the mounting method by flip chip, along with the mounting by heating.

From the same viewpoint, the time for maintaining these maximum reaching temperatures is preferably 2 seconds to 10 minutes, more preferably 5 seconds to 5 minutes, and particularly preferably 10 seconds to 3 minutes.

In addition, from the viewpoint of suppressing the occurrence of cracks in the anodic oxide film due to the difference in thermal expansion coefficient from the anodic oxide film, a method of performing heat treatment at a predetermined temperature for 5 seconds to 10 minutes, more preferably 10 seconds to 5 minutes, and particularly preferably 20 seconds to 3 minutes before the maximum reaching temperature is reached may be employed. The required certain temperature is preferably 80 to 200 ℃, more preferably 100 to 180 ℃, and particularly preferably 120 to 160 ℃.

The temperature at the time of mounting by wire bonding is preferably 80 to 300 ℃, more preferably 90 to 250 ℃, and particularly preferably 100 to 200 ℃ from the viewpoint of reliable mounting. The heating time is preferably 2 seconds to 10 minutes, more preferably 5 seconds to 5 minutes, and particularly preferably 10 seconds to 3 minutes.

< Wiring layer >

The wiring layer provided in the light source module of the present invention is a portion for driving the light emitting source, and is provided on the back surface of the insulating substrate of the present invention.

The material of the wiring layer is not particularly limited as long as it is a material to be energized, and specific examples thereof include gold (Au), silver (Ag), copper (Cu), aluminum (Al), magnesium (Mg), nickel (Ni), and the like, and 1 kind thereof may be used alone, or 2 or more kinds thereof may be used in combination.

Among them, Cu is preferably used for the reason of low resistance.

The thickness of the wiring layer is preferably 5 to 100 μm, more preferably 10 to 50 μm, and particularly preferably 15 to 40 μm, from the viewpoint of conduction reliability and compactness of the module.

Examples of the method of forming the wiring layer include various plating treatments such as electrolytic plating, electroless plating, and displacement plating, as well as sputtering, vapor deposition, vacuum adhesion of a metal foil, and adhesion with an adhesive layer.

Among them, a layer formed of only a metal is preferable from the viewpoint of high heat resistance, and a layer formed by plating is preferable from the viewpoint of thick film/uniform formation and high adhesion.

Since the plating treatment is a plating treatment for a non-conductive substance (anodic oxide film), a method of forming a thick metal layer by providing a reduced metal layer called a seed layer and then using the metal layer is preferably used.

In addition, in the formation of the seed layer, electroless plating is preferably used, and as the plating solution, a solution composed of a main component (for example, a metal salt, a reducing agent, or the like) and an auxiliary component (for example, a pH adjuster, a buffer, a complexing agent, an accelerator, a stabilizer, a modifier, or the like) is preferably used. Further, commercially available plating solutions such as SE-650. 666. 680, SEK-670. 797, SFK-63 (all manufactured by Kanigen, Japan), Melplate NI-4128, Enplate NI-433, and Enplate NI-411 (all manufactured by Meltex) can be suitably used.

When copper is used as a material of the wiring layer, various electrolytic solutions containing sulfuric acid, copper sulfate, hydrochloric acid, polyethylene glycol, and a surfactant as main components and other various additives may be used.

The wiring layer thus formed is patterned by a known method in accordance with the design of the light emission source mounted on the surface of the aluminum substrate with a film.

< lens >

In the light source module (backlight unit application) of the present invention, a lens is provided on an upper surface of the light emitting source as needed.

The lens is preferably designed to be able to further widen or concentrate the incident angle of the light emitted from the light-emitting source.

< diffusion sheet >

The light source module (backlight module application) of the present invention includes a diffusion sheet as needed, which is provided above the lens and below an LCD panel described later.

The diffusion sheet may be a laminate of a light diffusion sheet, a heat diffusion sheet, and the like, and specifically, for example, a diffusion sheet described in japanese patent application laid-open No. 2010-73476 may be mentioned.

< light guide plate >

The light source module (backlight module application) of the present invention has a function of refracting light incident from the light emission source as a surface light source by providing a light guide plate between the lens and the diffusion sheet as needed.

[ liquid Crystal display device ]

A liquid crystal display device of the present invention includes the light source module (backlight unit application) of the present invention described above and an LCD panel disposed on the light emitting side of the light source module.

Here, the LCD panel is not particularly limited, and may be appropriately selected from conventionally known panels.

[ examples ]

The present invention will be specifically explained below with reference to examples. However, the present invention is not limited to them.

(example 1)

< drilling (Via hole Forming step) >

First, an aluminum substrate (0.4 mm thick, manufactured by Nippon light metals Co., Ltd.) having an aluminum purity of 99.95 mass% was processed by a printed substrate outline processing machine (NR-G type, manufactured by Hitachi BIAMECHANICS Co., Ltd.) under conditions of a drill diameter of 0.8mm and a drill moving speed of 0.2m/min to form 20 through holes (a hole diameter of 0.8 mm. phi.).

In addition, in the machining, for the purpose of suppressing burrs, thin bakelite plates (0.8mmt) and thin aluminum plates (made by knoevenagel) coated with a hydrophilic resin were stacked on top of and below an aluminum substrate to be machined.

< electropolishing treatment (dissolution treatment step) >

Then, the aluminum substrate after the through-hole forming step was subjected to an electrolytic polishing treatment using a mixed acid of phosphoric acid and sulfuric acid at a temperature of 65 ℃ and a voltage of 10 for 300 seconds to dissolve the edge portion of the opening of the through-hole.

< routing (singulation step) >

Then, the aluminum substrate after the dissolution treatment step is subjected to routing processing, and can be singulated into 10 chips.

< anodic Oxidation treatment step >

Then, the aluminum substrate after the above-mentioned singulation step was anodized for 8 hours using an electrolytic solution of 0.30mol/L sulfuric acid at a voltage of 25V, a liquid temperature of 17 ℃ and a liquid flow rate of 3.0m/min, to obtain an insulating substrate having a uniform anodic oxide film thickness of 45 μm covering the entire surface (before singulation). In the anodic oxidation treatment, a stainless steel electrode was used as a cathode, and GP0110 to 30R (manufactured by Gaosha Ltd.) was used as a power source. NeoCool BD36 (manufactured by Yamato scientific Co.) was used as a cooling device, and Pairsterrer PS-100 (manufactured by EYELA) was used as a stirring and heating device. The flow rate of the electrolyte was measured by using a turbine flow meter FLM22-10PCW (manufactured by AS ONE).

Fig. 7 shows a processing chart such as dimensions of the obtained insulating substrate (before singulation). Further, as shown in FIG. 7, the final through-hole 3 had a hole diameter of 0.8 mm.

(example 2)

An insulating substrate was produced in the same manner as in example 1, except that the dissolution treatment step was replaced with the alkali etching treatment described below.

< alkaline etching treatment (dissolution treatment step) >

The aluminum substrate after the through-hole forming step was subjected to an alkali etching treatment of immersing the aluminum substrate in an aqueous solution (liquid temperature: 40 ℃) having a caustic soda concentration of 1 mass% for 40 seconds to dissolve the edge portion of the opening of the through-hole.

(example 3)

An insulating substrate was produced in the same manner as in example 2, except that an aluminum substrate (0.8mm thick, manufactured by light metal, japan) having an aluminum purity of 99.99 mass% was used.

(example 4)

An insulating substrate was produced in the same manner as in example 1, except that the singulation step was replaced with the die processing described below, and that the electrolytic polishing treatment (dissolution treatment step) was performed after the die processing (singulation step).

< mold processing (singulation step) >

First, a suitable mold was produced using Trim punch T302 manufactured by Yamaha Finetech corporation.

The aluminum substrate after the through-hole forming step was punched out using the die, and was singulated into 10 chips in the same manner as in example 1.

(example 5)

An insulating substrate was produced in the same manner as in example 4, except that an aluminum substrate (0.4 mm thick, manufactured by light metal japan) having an aluminum purity of 99.99 mass% was used.

(example 6)

An insulating substrate was produced in the same manner as in example 1, except that the through-hole forming step was replaced with wet etching as described below, the through-hole forming step and the dissolving treatment step were performed simultaneously, and the electrolytic polishing treatment was not performed.

< Wet etching (Via hole formation step and dissolution treatment step) >

First, oil and the like adhering to the surface of an aluminum substrate (0.4 mm thick, manufactured by light metal japan) having an aluminum purity of 99.95 mass% were removed with an alkali aqueous solution, and then a neutralization treatment using an acidic aqueous solution was performed. The neutralization treatment also has a function as a surface treatment for improving adhesion between the photoresist (insulating layer) and the surface of the aluminum substrate when the photoresist is coated thereafter.

Then, the insulating layers (epoxy resin, thickness: 10 μm, ABF GX-13, manufactured by Genetichno corporation) from which the protective films were removed were attached to both surfaces of the aluminum substrate using a Dry Film Resist (DFR) automatic cutting laminator.

After the insulating layer was attached, the film was attached by a pressure vacuum laminator (V130 manufactured by Nichigo Morton corporation) at 180 ℃ for 30 minutes, and after gradually cooling to room temperature, the support film (PET) originally supporting the insulating layer was peeled off.

Then, a glass mask having a predetermined light-shielding pattern formed thereon is closely adhered to the surface of the aluminum substrate, and pattern exposure is performed by irradiation with ultraviolet rays, thereby curing the insulating layer in a region other than the light-shielding pattern portion of the glass mask.

Then, the substrate was developed by spraying a 1% aqueous solution of sodium carbonate at 30 ℃ to remove the epoxy resin in the unexposed portions, and then the remaining insulating layer was further heated to solidify the insulating layer.

Then, the aluminum was dissolved and removed with an etching solution (a mixed solution of copper chloride and hydrochloric acid) using the photoresists formed on both surfaces of the aluminum substrate as masks, thereby forming 20 through holes (having an aperture of 0.8 mm. phi.).

Finally, the unnecessary photoresist is immersed in an alcohol amine-based liquid to be removed.

(example 7)

An insulating substrate was produced in the same manner as in example 6, except that the same electrolytic polishing treatment (dissolution treatment step) as in example 1 was performed after the wet etching treatment (through-hole forming step).

Comparative example 1

An insulating substrate was produced in the same manner as in example 1, except that the electrolytic polishing treatment (dissolution treatment step) was not performed.

Comparative example 2

An insulating substrate was produced in the same manner as in example 1, except that the time for the electrolytic polishing treatment was changed to 30 seconds.

Comparative example 3

An insulating substrate was produced in the same manner as in example 1, except that an aluminum substrate (0.8mm thick, manufactured by light metal japan) having an aluminum purity of 99.99 mass% was used.

For each of the insulating substrates thus produced, the maximum diameter (d) of each through-hole was measured₀) And minimum diameter (d)_r) Difference (d) of₀-d_r) And an average value is calculated. The results are shown in table 1.

< Presence or absence of cracks & cracks >

The insulating substrates thus produced were each singulated into 10 pieces.

The monolithic insulating substrates (chips) were placed in ceramic cases made of mullite on zirconium ceramic beads having a diameter of 1mm, each ceramic case was placed in an electric furnace heated to 200 ℃ in advance, held for 1 hour, taken out, and naturally cooled. The zirconium ceramic beads are used for eliminating the influence of the restriction on the contact points due to the expansion and contraction caused by heat.

After cooling, the appearance of 10 chips was evaluated visually and by optical microscope observation, and the number of chips having cracks or fissures in the anodic oxide film in the vicinity of the opening of the through hole was investigated, 8 or more were evaluated as x, 4 to 7 were evaluated as Δ, 2 to 3 were evaluated as Δ, 1 was evaluated as ∘, and 0 was evaluated as ^.

< insulation breakdown Voltage >

The insulation breakdown voltage (withstand voltage) of the obtained insulating substrate was measured by the method according to JISC2110 standard. The results are shown in table 1.

[ Table 1]

Table 1

As can be seen from the results shown in Table 1, if the maximum diameter (d) of each through-hole is set₀) And minimum diameter (d)_r) Difference (d) of₀-d_r) If the thickness is less than half or more of the thickness, the number of chips having cracks or fissures in the anodic oxide film near the opening of the through hole is reduced, and the insulation (withstand voltage) is also improved.

Claims

1. An insulating substrate comprising an aluminum substrate and a through hole formed to penetrate the aluminum substrate in a thickness direction thereof, wherein at least a front surface and a back surface of the aluminum substrate and an inner wall surface of the through hole are covered with an anodic oxide film,

maximum diameter d of the through-hole₀And a minimum diameter d_rThe relationship with the thickness t of the insulating substrate satisfies the following formula (I).

0.5×t≤(d₀-d_r)＜t…(I)

2. The insulating substrate according to claim 1, wherein the aluminum purity of the aluminum substrate is 99.90 mass% or more.

3. The insulating substrate according to claim 1, for LED use.

4. A method for manufacturing an insulating substrate, which is a method for manufacturing an insulating substrate according to any one of claims 1 to 3, comprising:

a dissolution treatment step of performing a dissolution treatment after the through-hole forming step to dissolve at least an edge portion of an opening of the through-hole; and

and an anodic oxidation treatment step of performing anodic oxidation treatment after the dissolution treatment step to cover the front and back surfaces of the aluminum substrate and the inner wall surfaces of the through holes with an anodic oxide film.

5. The method for manufacturing an insulating substrate according to claim 4, wherein the dissolving process is a photolithography process.

6. The method of manufacturing an insulating substrate according to claim 4, wherein a singulation step of singulating the aluminum substrate into a desired shape is provided after the through hole forming step and before the anodizing step.

7. A light source module is provided with:

the insulating substrate according to any one of claims 1 to 3,

A light-emitting source mounted on the surface of the aluminum substrate, and

and the wiring layer is arranged on the back surface of the aluminum substrate and penetrates through the through hole to be electrically connected with the light-emitting source.

8. The light source module of claim 7, wherein the light emitting source is an LED.

9. The light source module of claim 7, for backlight assembly use.

10. A liquid crystal display device includes: the light source module according to claim 9, and a liquid crystal display panel disposed on a light exit side of the light source module.