KR100757901B1 - Printed circuit board and fabricating method thereof - Google Patents

Abstract

A PCB(Printed Circuit Board) and a method for manufacturing the same are provided to improve electrical insulation on an insulating layer by attaching a minute particle having the electrical insulation. A PCB(100) includes a metal substrate, an insulating layer(110), and a conductive line(120). The insulating layer(110) is formed on an upper part of the metal substrate. High polymer particles(116) with a heat conductive minute particle(113) and an electrical insulation minute particle are dispersed on a surface of the insulating layer(110). The conductive line(120) is formed on an upper part of the insulating layer(110). The metal substrate is made of aluminum. The electrical insulation minute particle is a glass based material. The size of the heat conductive minute particle(113) and the electrical insulation minute particle is 0.01 - 20 um.

Description

Printed circuit board and manufacturing method thereof

1 is a view showing a state in which a light emitting diode package is mounted on a printed circuit board.

Figure 2 is a cross-sectional view showing an embodiment of a printed circuit board of the present invention.

Figure 3 is a cross-sectional view showing another embodiment of a printed circuit board of the present invention.

Figures 4a to 4d schematically show an embodiment of a method of manufacturing a printed circuit board of the present invention.

5 is a view showing a state in which thermally conductive fine particles are unevenly distributed in an insulating layer.

Figure 6 is a schematic view showing another embodiment of the method of manufacturing a printed circuit board of the present invention.

Explanation of symbols on the main parts of the drawings

100, 150: substrate 110, 160: insulating layer

113, 163: thermally conductive fine particles 116, 169: polymer particles

166: electrically insulating fine particles 120, 170: circuit electrode layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board and a method of manufacturing the same, and more particularly, to a printed circuit board having improved heat dissipation capability by dispersing polymer particles having thermally conductive fine particles attached to a surface thereof in an insulating layer of the printed circuit board. It relates to a manufacturing method.

Recently, research on flat panel displays has been actively conducted. Among them, liquid crystal display (LCD), FED (Field Emission Display), organic EL (Electro-luminescence), PDP (Plasma Display) Panel).

Among them, the liquid crystal display is an element that transmits or blocks light by changing an arrangement of liquid crystals by applying an electrical signal to each pixel in a liquid crystal panel positioned between two polarizers.

The liquid crystal display device has a large contrast ratio, is suitable for gray scale display or moving image display, and has low power consumption. Therefore, the area of the liquid crystal display has been expanded to mobile phones, notebook PCs, desktop monitors, and liquid crystal TVs. .

However, since the liquid crystal display itself is non-luminescent, a separate external light source for irradiating light is required. In particular, in the case of a transmissive liquid crystal display, a separate dimming device that emits light and guides the back of the LCD panel, that is, a back light unit (BLU) is necessary.

The light source used in the backlight unit includes a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), and a light emitting diode (LED).

Until now, cold cathode fluorescent lamps have been mainly used as a light source for backlight units, but the adoption of light emitting diodes having advantages of high lifespan, low power consumption, and thinning is increasing, and it is expected that LEDs will lead the light source market in the future. have.

On the other hand, the stricter environmental regulations such as RoHS (Restriction of Hazardous Substance), etc. limit the use of cold cathode fluorescent lamps using mercury, and as an alternative to this is accelerating the development of a backlight unit using a light emitting diode as a light source.

However, the light emitting diode is difficult to use as a light source of the backlight unit due to the low light efficiency and the heat problem generated in the light emitting diode.

The light efficiency of the light emitting diode is about 20-30%. The power consumption per light emitting diode is about 1W, and when the light efficiency is 30% at the power consumption of 1W, the power consumption rate generated by heat is about 70%.

The number of light emitting diodes used in the backlight unit of the 32-inch liquid crystal display device is about 400, where the power consumed by heat is about 280W.

If the heat generated from the printed circuit board (PCB) mounted with the light emitting diode is not processed, the temperature inside the printed circuit board and the backlight unit on which the light emitting diode is mounted may be increased, thereby preventing the operation of the LED lamp. It may cause the deterioration of the operation reliability of the associated electronic circuit. In addition, thermal stress may occur in parts or cases due to internal temperature differences, which may cause deformation of the product.

Accordingly, various methods for quickly dissipating heat generated from light emitting diodes to the outside have been proposed. The most common heat dissipation method is using a heat sink or a cooling fan, which increases the price and requires a separate device for dissipating the transferred heat. .

1 is a view showing a state in which a light emitting diode package is mounted on a printed circuit board. As shown in the drawing, the light emitting diode package 13 has an insulating layer 11 formed on an aluminum substrate 10 and a conductive line 12 formed on the insulating layer 11. It is mounted on

Openings 21 are formed periodically or aperiodically in the conductive line 12 of the printed circuit board, and a light emitting diode 13 package is mounted around each opening 21.

The light emitting diode 14 is bonded on the conductive heat slug 15, and the conductive heat slug 15 is soldered on the circuit electrode layer 13. The negative electrode and the positive electrode of the light emitting diode 14 are wire-bonded to the conductive wires 31 and 32 which electrically connect the conductive line 12 and the conductive heat slug 15, respectively.

Here, heat generated in the LED package 13 is discharged to the aluminum substrate 10 through the circuit electrode layer 12 and the insulating layer 11 of the copper pattern.

Aluminum is used as a substrate of a metal printed circuit board because of good thermal conductivity, light weight, and low cost. The problem is that the thermal conductivity of the insulating layer 11 between the aluminum substrate 10 and the conductive line 12 is much higher than that of the two metals. Has a low value. Therefore, there is a problem that heat generated in the light emitting diode package 13 is not easily released.

The insulating layer 11 is mostly made of an epoxy-based adhesive material, the thermal conductivity of the insulating layer 11 is a factor that determines the thermal conductivity of the entire printed circuit board.

Accordingly, an object of the present invention is to provide a printed circuit board and a method of manufacturing the same, by improving the heat dissipation capability of the printed circuit board by uniformly distributing fine particles having high thermal conductivity in the insulating layer of the printed circuit board.

A preferred embodiment of the printed circuit board of the present invention is a metal substrate, an insulating layer formed on top of the metal substrate, the polymer particles with thermally conductive fine particles attached to the surface and the conductive layer formed on the insulating layer Characterized in that it comprises a line.

Preferred embodiments of the method of manufacturing a printed circuit board of the present invention include the steps of attaching thermally conductive fine particles to the surface of the polymer particles, mixing the polymer particles with an epoxy resin, and then making an insulating film; After placing the insulating film on the substrate, forming a metal layer, applying the heat and pressure to the metal substrate, the insulating film, and bonding the metal layer, and patterning the metal layer to form conductive lines. Characterized in that made.

Hereinafter, a printed circuit board and a method of manufacturing the same will be described in detail with reference to FIGS. 2 to 6.

2 is a cross-sectional view showing an embodiment of a printed circuit board of the present invention. As shown in the drawing, the printed circuit board of the present invention includes an insulating layer 110 formed on the substrate 100 and a conductive line 120 formed on the insulating layer 110, and the insulating layer 110. ), The polymer particles 116 to which the thermally conductive fine particles 113 are attached are uniformly distributed.

Here, the substrate 100 uses a material having excellent thermal conductivity to effectively release heat to the outside, it is preferable to use aluminum having a thermal conductivity of about 200 W / m · K.

As such, when the polymer particles 116 to which the fine particles 113 having high thermal conductivity are attached are dispersed in the insulating layer 110 having a lower thermal conductivity than the substrate 100 or the conductive line 120, the printed circuit board It is possible to increase the overall thermal conductivity of the PCB, thereby improving the heat dissipation capability of the printed circuit board.

The polymer particles 116 may be the same or different types of epoxy resins constituting the insulating layer 110, and in addition, polymers such as acrylic, urethane, ethylene, phenol resin, melamine resin, urea resin, and polyester resin Particles can be used.

In addition, the size of the polymer particles 116 is 1 to 100 ㎛, preferably 1 to 30 ㎛.

As the thermally conductive fine particles 113 attached to the surface of the polymer particles 116, nitrides such as AlN, BN, Si ₃ N ₄ , and Al ₂ O as well as Ag, Au, Cu, etc., which are basically metals having excellent thermal conductivity, may be used. Oxide-based materials such as ₃ , SiO ₂ , ZnO, MgO, and CNT (Carbon Nano Tube) and Carbon Fiber can be used.

The thermally conductive fine particles 113 have a size of 0.01 to 20 μm, particularly preferably 0.05 to 10 μm.

3 is a cross-sectional view showing another embodiment of a printed circuit board of the present invention. As shown therein, the insulating layer 160 and the conductive line 170 are sequentially formed on the aluminum substrate 150, and the thermally conductive fine particles 163 and the electrical insulating layer are formed on the surface of the insulating layer 160. The polymer particles 169 to which the fine particles 166 are attached are uniformly distributed.

In the present embodiment, the thermally conductive fine particles 163 and the electrically insulating fine particles 166 are uniformly distributed on the surface of the polymer particles 169 attached to the surface, in this case, the insulating layer 160 In addition to improving the thermal conductivity, the insulating layer 160 has an effect of further improving the electrical insulation, which is an inherent characteristic of the insulating layer 160.

As the electrically insulating fine particles 166, glass-based particles such as Al ₂ O ₃ and SiO ₂ may be used, and the size of the electrically insulating fine particles 166 may be the size of the thermally conductive fine particles 163. In the same manner as in the case of 0.01 to 20 ㎛, particularly preferably from 0.05 to 10 ㎛.

As described above, according to the present invention, fine particles are dispersed in the insulating layer of the printed circuit board to improve desired characteristics (for example, thermal conductivity and electrical insulation). Thermal conductivity, electrical insulation) can be improved.

Here, although the thermal conductivity, electrical insulation, etc. have been described as an example, embodiments of the present invention are not limited thereto, and fine particles may be used to improve various characteristics.

4A to 4D are schematic views illustrating one embodiment of a method of manufacturing a printed circuit board of the present invention. As shown therein, first, the thermally conductive fine particles 210 are attached to the surface of the polymer importer 220 (FIG. 4A).

Here, the adhesion between the particles is a mixture of the thermally conductive microparticles 210 and the polymer particles 220 in a constant ratio, and then apply a physical impact and shear stress to the surface of the polymer particles 220 thermally conductive fine particles ( 210 is attached to, means that the physical coupling between the heterogeneous. This process can be performed in a short time in a dedicated chamber equipped with a high speed rotor.

As the thermally conductive fine particles 210, not only Ag, Au, Cu, etc., which are metals having excellent thermal conductivity, but also nitrides such as AlN, BN, Si ₃ N ₄ , and oxides such as Al ₂ O ₃ , SiO ₂ , ZnO, MgO, etc. Materials having excellent thermal conductivity such as CNT (Carbon Nano Tube) and Carbon Fiber are used, and the particle size is preferably 0.01 to 20 μm.

The polymer particles 220 may be acrylic, urethane, ethylene, phenolic resins, melamine resins, urea resins, epoxy resins, polyester resins, and the like. The particle size is preferably 1 to 100 μm.

Next, after the thermally conductive fine particles 210 are mixed with the polymer particles 220 attached to the surface with the epoxy resin 230, an insulating film 240 is formed through a tape casting process ( 4b).

That is, de-airing is performed to prepare a suspended slurry by adding organic solvents such as a solvent, an epoxy resin, a dispersant, and a plasticizer to the polymer particles 220 and to remove bubbles contained in the slurry. After roughing it, put it in the caster

The caster is equipped with a film, and when the slurry is subjected to the defoaming process while moving the film at a constant speed, an insulating thin film is formed on the moving film while passing under the blade adjusted to have a constant height with the film. When the thick film is subjected to a moderately controlled drying process, a dense and flexible insulating film 240 is obtained.

Here, in addition to the method of using a take caster, a method of manually tapening an epoxy using a doctor blade can also be used.

Subsequently, an insulating film 240 on which the polymer particles 220 are dispersed is placed on the metal substrate 250 such as aluminum, and then a metal layer 260 is formed on the insulating film 240 (FIG. 4C). ).

Thereafter, a laminating process of applying heat and pressure to bond the metal substrate 250, the insulating film 240, and the metal layer 260 to each other is performed (FIG. 4D). At this time, the temperature is applied to the heat curing point of the epoxy resin 230 in the insulating film 240.

Here, when the polymer particles 220 have a melting point at a temperature lower than the heat curing point temperature of the epoxy resin 230, the polymer particles melt before reaching the heat curing point of the epoxy resin 230, and thus the surface of the polymer particles 220. Position of the thermally conductive fine particles 210 attached to the is significantly disturbed.

As such, when the thermally conductive fine particles 210 are unevenly distributed in the insulating film 240, it is difficult to obtain a desired thermal conductivity.

In more detail, in general, when a material capable of improving thermal conductivity is added to an insulating layer of a printed circuit board, the thermal conductivity may be remarkably affected depending on how well the epoxy resin and the additive of the insulating layer are mixed.

That is, the thermally conductive fine particles must be uniformly incorporated in the insulating layer to obtain the desired thermal conductivity.

In the present invention, the thermally conductive fine particles are uniformly distributed in the insulating layer through the polymer particles. In other words, by attaching the thermally conductive fine particles to the surface of the polymer particles so that their positions are fixed, the thermally conductive fine particles can be uniformly distributed in the insulating layer.

However, in performing the laminating process, when the polymer particles 220 have a melting point lower than the thermal curing point temperature of the epoxy resin 230, the polymer particles melt before reaching the thermal curing point of the epoxy resin 230. The position of the thermally conductive fine particles 210 adhered to the surface of the polymer particles 220 is significantly disturbed, so that the desired thermal conductivity is not obtained.

Therefore, in the case of the polymer particles 220, a material having a melting point higher than the thermal curing point temperature of the epoxy resin 230 should be used.

Since the present invention is characterized in that the thermally conductive fine particles 210 are uniformly distributed in the insulating layer using the polymer particles 220, the polymer particles 220 do not melt all of the polymer particles 220 during the laminating process. ) Should be selected in comparison with the thermal curing point of the epoxy resin 230.

Next, after the photoresist is formed on the metal layer 260, the photoresist is patterned and the metal layer 260 is etched using the patterned photoresist as an etch mask, thereby conducting the conductive film on the insulating film 240. Form a line.

5 is a view illustrating a state in which thermally conductive fine particles are unevenly distributed in an insulating layer. As shown in FIG. 2, when the thermally conductive fine particles 315 are unevenly distributed in the insulating layer 310, the thermally conductive fine particles 315 are mixed with the epoxy resin without adhering to the surface of the polymer particles. When the insulating layer 310 is formed and ㉡ the melting point of the polymer particles is lower than the thermosetting point of the epoxy resin, the polymer particles are melted during the thermal curing process of the insulating layer 310 and the position of the thermally conductive fine particles is significantly changed. There can be.

Therefore, in the present invention, the thermally conductive fine particles are attached to the surface of the polymer particles, and then mixed with the epoxy resin to form an insulating layer, but when the polymer particles are selected, a material having a melting point higher than the thermal curing point of the epoxy resin is used. Thus, even after performing the laminating process, the thermally conductive fine particles are uniformly distributed in the insulating layer.

6 is a view schematically showing another embodiment of a method of manufacturing a printed circuit board of the present invention. As shown therein, the thermally conductive fine particles 410 and the electrically insulating fine particles 420 are attached to the surface of the polymer particles 430.

That is, after the thermally conductive fine particles 410 and the electrically insulating fine particles 420 and the polymer particles 430 are mixed in a dedicated chamber in which a high speed rotor is installed, the polymers may be subjected to physical impact and shear stress. The thermally conductive fine particles 410 and the electrically insulating fine particles 420 are attached to the surface of the particles 430.

The subsequent process is the same as shown in FIG. 4, whereby the polymer particles 430 having the thermally conductive fine particles 410 and the electrically insulating fine particles 420 attached to the surface are uniformly distributed in the insulating layer of the printed circuit board. This makes it possible to improve thermal conductivity and electrical insulation in the insulating layer.

On the other hand, while the present invention has been shown and described with respect to specific preferred embodiments, various modifications and variations of the present invention without departing from the spirit or field of the invention provided by the claims below It will be readily apparent to one of ordinary skill in the art that it can be used.

That is, the printed circuit board of the present invention may be used for a light emitting diode package of a backlight unit of a liquid crystal display device, or may be used for a power circuit chip requiring high heat emission capability in order to maintain high reliability for a long time.

According to the present invention, the thermal conductivity of the printed circuit board can be improved by dispersing the polymer particles having the thermally conductive fine particles adhered in the insulating layer of the printed circuit board.

In addition, by adhering not only thermally conductive fine particles but also particles exhibiting other properties, for example, fine particles exhibiting electrical insulation, the polymer particles have an effect of further improving electrical insulation in the insulating layer.

In addition, by attaching the thermally conductive fine particles to the polymer particles and dispersed in the insulating layer to give a uniform distribution and uniform intervals between the metal particles, it is possible to prevent electrical short circuit due to the electrical conductivity of the thermally conductive fine particles and high thermal conductivity There is an effect that can provide.

Claims (14)

Metal substrates; An insulating layer formed on the metal substrate and having polymer particles having thermally conductive fine particles and electrically insulating fine particles adhered thereon; And Printed circuit board comprising a conductive line formed on the insulating layer. delete The method of claim 1, Printed circuit board, characterized in that the metal substrate is made of aluminum. The method of claim 1, The thermally conductive fine particles are any one or two materials selected from Au, Ag, Cu, AlN, BN, Si ₃ N ₄ , Al ₂ O ₃ , SiO ₂ , ZnO, MgO, Carbon Nano Tube (CNT), Carbon Fiber A printed circuit board comprising the above material. The method of claim 1, The electrically insulating fine particles are printed circuit board, characterized in that the glass (Glass) material. The method of claim 1, The size of the thermally conductive particles and electrically insulating particles is a printed circuit board, characterized in that 0.01 ~ 20 ㎛. Attaching the thermally conductive fine particles and the electrically insulating fine particles to the polymer particle surface; Mixing the polymer particles with an epoxy resin and then making an insulating film; Placing the insulating film on the metal substrate, and then forming a metal layer; Attaching the metal substrate, the insulating film, and the metal layer by applying a constant heat and pressure; And The method of manufacturing a printed circuit board comprising the step of forming a conductive line by patterning the metal layer. delete The method of claim 7, wherein The thermally conductive fine particles are any one or two materials selected from Au, Ag, Cu, AlN, BN, Si ₃ N ₄ , Al ₂ O ₃ , SiO ₂ , ZnO, MgO, Carbon Nano Tube (CNT), Carbon Fiber A method of manufacturing a printed circuit board comprising the above materials. The method of claim 7, wherein The polymer particle manufacturing method of a printed circuit board, characterized in that made of any one selected from acrylic, urethane, ethylene, phenol resin, melamine resin, urea resin, epoxy resin, polyester resin. The method of claim 7, wherein The size of the polymer particles is a manufacturing method of a printed circuit board, characterized in that 1 ~ 100㎛. The method of claim 7, wherein The thermally conductive particles and the electrically insulating particles have a size of 0.01 ~ 20 ㎛ printed circuit board manufacturing method. The method of claim 7, wherein Attaching the thermally conductive particles and electrically insulating particles to the surface of the particles, The method of manufacturing a printed circuit board, characterized in that by rotating and attaching the thermally conductive particles, electrically insulating particles and polymer particles. The method of claim 7, wherein The polymer particle manufacturing method of the printed circuit board, characterized in that the melting point is higher than the thermal curing point temperature of the epoxy resin.

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