KR100955451B1 - Heat radiant fpcb and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A heat radiant FPCB and a manufacturing method thereof are provided to efficiently discharge heat from an LED by forming an inorganic coating layer and a heat sink on the lower side of the FPCB. CONSTITUTION: An FCCL(Flexible Copper Clad Laminate) layer(130) is formed by laminating a copper foil on both sides of a polyimide film. A copper plate layer(120) is formed on both sides of the FCCL layer. A heat sink substrate(230) is attached to one side of the copper plate layer and includes a heat sink(210), an inorganic coating layer(220), and a thermal conductive tape(200). The inorganic coating layer is formed on one side of the heat sink. The thermal conductive tape is attached to the other side of the heat sink.

Description

Heat radiant FPCB and Method for manufacturing the same

The present invention relates to the invention FPCB (Flexible Printed Circuit Board (FPCB)) and a method of manufacturing the same, more specifically, when the LED (Light Emitted Diode) is mounted a lot of heat is generated to effectively release this heat An FPCB and a method for producing the FPCB.

Light emitting diodes (hereinafter referred to as LEDs) are devices that realize light emission by electric field effect by depositing a compound semiconductor thin film on a substrate, and are recently being actively used as displays for lighting, communication, and various electronic devices.

Among various applications of LEDs, each researcher is actively working on the back light unit (BLU) used in thin-film TVs such as LCDs and the lighting field that can replace fluorescent lamps. In order to apply LEDs to these applications, researches on the structure, material, and package of LEDs are very active. The manifestation of the function of the LED is the process of injecting electrons and holes and emitting energy in the form of light when they are combined and dissociated.

However, as the development of high-power LEDs with LED chip sizes of 1 mm × 1 mm or more, the brightness of LEDs has been realized at more than 10 cd, and the LED modules also have a number of high-power chips. Used in units and lighting modules.

The LEDs used in these applications emit a lot of heat, so the temperature of the heat released is very high. However, in the case of LED, since the brightness of the light is inversely proportional to the heat of the LED, there is a problem in that reliability and required brightness of the light are implemented without solving the problem of heat in the FPCB equipped with the LED.

A diagram showing the substrate structure of this FPCB is shown in FIG. That is, referring to FIG. 1, the substrate structure of the FPCB includes the LED 100, the vias 110, the copper layers 120 and 121, the flexible copper clad laminate (FCCL) layer 130, the bonding sheet 140, and the like. It is composed of an aluminum layer 150.

In the process of manufacturing this FPCB, a secondary molding process of applying a heat of about 120 ° C. is required to attach a thermal conductive bonding sheet to the lower copper layer 120, which is expensive in manufacturing and easily prone to defects. There is a problem.

The present invention has been proposed to solve the problems posed by the prior art, and an object thereof is to provide a heat dissipation FPCB that easily dissipates heat when mounting an optical device that generates a lot of heat, such as LED.

It is another object of the present invention to provide a method of manufacturing a heat dissipating FPCB which shortens the process and reduces defects by eliminating the secondary molding process of attaching the thermal conductive bonding sheet.

In order to achieve the object described above, one embodiment of the present invention provides a heat dissipation FPCB. The heat dissipating FPCB includes an FCCL layer having copper foil formed on both sides of the polyimide film and the polyimide film, a copper plate layer formed on both sides of the FCCL layer, and a heat sink substrate attached to one surface of the copper plate layer. .

In this case, the heat sink substrate may include a heat sink, an inorganic coating layer formed on one surface of the heat sink, and a double-sided thermal conductive tape adhered to one surface of the heat sink in a direction opposite to the inorganic coating layer.

Here, the heat sink substrate may be made in advance of the heat sink, the inorganic coating layer and the thermal conductive tape as a set.

Another embodiment of the present invention provides a method for providing this heat dissipation FPCB. The manufacturing method includes cutting a flexible copper clad laminate (FCCL) to form and drill a flexible printed circuit board (FPCB) substrate, copper plating and attaching a dry film to the FPCB substrate to form a circuit pattern. And attaching the cover layer to the cover layer, hot pressing the cover layer to the FPCB substrate, and attaching a heat sink substrate to one side of the FPCB substrate without an additional hot press process.

In this case, attaching the heat sink substrate to one side of the FPCB substrate without a hot press process may include attaching an inorganic coating layer to the heat sink of the heat sink substrate, and attaching a double-sided thermal conductive tape to the heat sink. It may include.

Here, the inorganic coating layer is 50 to 60% of the silicone resin (Silicone resin), 1 to 5% of the melamine resin (Melamine resin), 1 to 5% of xylene (Xylene), 1 to 5% of cyclohexanone ( Cyclonhexanone, 10-20% Black Pigment, 20-30% supplement ingredients. Here, the supplement may be manganese dioxide (MnO ₂ ).

In addition, attaching an inorganic coating layer to a heat sink of the heat sink substrate, and attaching a double-sided thermal conductive tape to the heat sink may be made prior to fabrication of the FPCB substrate.

According to the present invention, since a heat sink and an inorganic coating are attached to the lower side of the FPCB, heat can be effectively released even when a heat generating element such as an LED is mounted.

Another effect of the present invention is that since the heat sink and the inorganic coating are attached to the FPCB without the secondary molding process of attaching the thermal conductive bonding sheet, the manufacturing process is simplified, and defects and manufacturing costs are reduced.

Hereinafter, a release FPCB and a method for manufacturing the release FPCB according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view showing a substrate structure of a heat dissipation FPCB according to an embodiment of the present invention. In the substrate structure of the heat dissipation FPCB according to an embodiment of the present invention, a copper plate layer 120, a flexible copper clad laminate (FCCL) 130, a copper plate layer 121, and a thermal conductive tape ( 200, a heat sink 210, an inorganic coating layer 220, and the like.

Of course, the light emitting diode (LED) 100 is shown in FIG. 2, but this is for understanding one embodiment of the present invention. Since the embodiment of the present invention is for a heat dissipation FPCB, the LED is not included. Will have to understand.

In describing these layers, the copper plate layer 120 is stacked on the top side, and the FCCL 130 is stacked on the bottom layer. Of course, the copper plate layer 120 is laminated to a thickness of about 13㎛, one embodiment of the present invention is not limited thereto.

FCCL (130) is a copper clad laminate (FCCL: Flexible Copper Clad Laminate), a heat-resistant flame-retardant epoxy-based adhesive coated on a polyimide film and a copper foil (copper foil: copper foil) is laminated thereon. A diagram showing this is shown in FIG. 3. This will be described later.

The FCCL 130 is mainly used for circuit boards that require light and thin components or conformational mounting, and usually has a polyimide of 25 mu m and a copper foil of 32 mu m.

After the FCCL 130, a copper plate layer 121 is formed. The copper plate layer 121 has the same properties and thickness as the copper plate layer 120 placed on the top layer.

Underneath this copper plate layer 121 is a thermally conductive tape 200. In general, it is also referred to as adhesive, and it is used by mixing acryl and epoxy, and it is divided into ACRYLIC TYPE (THERMOPLASTIC) and EPOXY TYPE (THERMOSETTING).

The thermally conductive tape 200 is a double-sided tape, and both surfaces thereof have adhesive properties. These thermally conductive tapes 200 are used in the production process of FPCB or in the use of finished products, and the thickness is usually 25 to 40 μm. It is also characterized by being stable at high temperatures and having thermal conductivity.

The heat sink 210 is formed under the thermally conductive tape 200. The heat sink 210 may be a copper plate with thermal conductivity splashed therein, but the present invention is not limited thereto. That is, when heat radiated from the LED 100 shown in FIG. 2 is transferred to the copper plate layer 121, the copper plate layer 121 has excellent thermal conductivity, and thus, the inorganic coating layer 220 directly below. It performs the function of transferring heat rapidly. Usually the thickness is 110 mu m.

The inorganic coating layer 220 serves as a thermally conductive filler to diffuse heat transferred from the heat sink 210 to rapidly release heat to the outside. That is, the thermal diffusion effect pops out. For this purpose, the inorganic coating layer 220 has a component as shown in the following table.

Component Composition Rate (%) Silicone resin Silicone resin ) 50-60 Melamine resin Melamine resin ) 1-5 xylene( Xylene ) 1-5 Cyclohexanone ( Cyclonhexanone ) 1-5 Black pigment ( Black Pigment ) 10-20 Supplement 20-30

Here, the supplement may be manganese dioxide (MnO ₂ ), but one embodiment of the present invention is not limited thereto, and any chemical substance having the same chemical properties as manganese dioxide may be used.

Of course, vias 110 pass through the FCCL layer 130 and the copper plate layer 120 stacked above and below the FCCL layer 130. The via 110 serves to dissipate heat transferred from the LED 100 to the FCCL layer 130 and the copper plate layer 120 to the outside.

Via 110 may also be drilled with a small drill lead, typically made of tungsten carbide solids. It is also possible to penetrate the entire board, and to make holes connecting only a few copper plate layers, it is also possible to drill "controlled depth" or pre-punch each printed circuit board before lamination. These holes are called "blind vias" when the inner and outer layers are connected, and "bary vias" when the inner layers are connected.

In FIG. 2, although the thermal conductive tape 200, the heat sink 210, and the inorganic coating layer 220 are all stacked, the thermal conductive tape 200, the heat sink 210, and the inorganic coating layer 220 are stacked. It is assembled in one set (hereinafter, referred to as heat sink substrate 230) in advance. That is, the heat sink substrate 230 has a structure in which the heat sink 210 is laminated on the inorganic coating 220 and the thermal conductive tape 200 is laminated on the heat sink 210.

2, a more detailed structure of the heat dissipation FPCB according to an embodiment of the present invention will be described. The figure for this is shown in FIG. 3. That is, FIG. 3 is a cross-sectional view showing a detailed substrate structure in which the thermal conductive tape 200, which is a polyimide and an adhesive layer, is laminated on the heat dissipating FPCB of FIG.

Of course, the LED 100 shown in FIG. 2 is mounted on the copper plate layer 120, which is omitted in FIG. 3, and regions other than the LED 100 is mounted on the polyimide layer 300 and the thermal conductivity. Tape 301 is stacked to form a cover layer 320.

Here, polyimide has good insulation and high TG (glass transition temperature), so it has little dimensional deformation even at high temperatures, and is excellent in heat resistance and flexibility. Of course, there are also features that are excellent in chemical resistance and moisture resistance. Of course, in addition to polyimide, any material having such performance and conditions may be used. For example, polyethylene terephthalate (PET) FILM may be used.

Polyimide layer 300 is usually 1 Mil Polyimide is used, the thickness is about 25㎛. Of course, this is for illustrative purposes and other thicknesses are possible, for example 2 Mil Polyimide, 0.5 Mil Polyimide.

The copper plate layer 120 described in FIG. 2 is formed below the thermal conductive tape 301.

An FCCL layer 130 is formed below the copper plate layer 120, and the FCCL layer 130 is a raw material composed of copper foil layers 310 and 314 and polyimide 312. That is, the copper foil layer 314 is laminated on the bottom layer, and the polyimide layer 312 and the copper foil layer 310 are sequentially stacked on the copper foil layer 314.

As the copper foil layers 310 and 314, electrolytic copper foil (ED) is generally used, but rolled copper foil (Rolled Anealed Cu) may be used. The thickness becomes about 32 micrometers.

Under the FCCL layer 130, as described with reference to FIG. 2, a copper plate layer 121, a thermal conductive tape 200, a heat sink 210, and an inorganic coating layer 220 are formed.

Figure 4 is a comparison table comparing the experimental results of the heat dissipation FPCB according to an embodiment of the present invention and the FPCB according to the prior art. That is, Figure 4 is a heat dissipation FPCB 400 according to an embodiment of the present invention having a substrate structure described in Figures 2 and 3 above, the FPCB 410, sus (SUS) with a conventional reinforcement plate is attached Is a view showing the experimental results of the FPCB 420.

In the case of the heat dissipating FPCB 400 according to an embodiment of the present invention, as shown in the temperature-time graph 402, the temperature of the LED (100 of FIG. 2) shows a constant temperature distribution curve. This temperature-time graph 402 is a screen example captured on a program.

Referring to graph 402, it can be seen that as time passes the temperature remains constant near 150 ° C. In this temperature-time graph 402, the x-axis represents elapsed time and the y-axis represents temperature. Channel 1, channel 3 and channel 5 channel 7 are displayed, and the temperature measurement point is the LED part which is the upper surface of the PCB, and the thermal sheet which is the lower surface, and eight temperature sensor channels are provided in this part.

This temperature-time graph 402 shows a case where only three of these channels are used. That is, the measurement point is an LED part, a thermal sheet, and room temperature.

Graph 404 shows this temperature-time graph 402 in more detail. In other words, the data values are output and displayed as graphs. That is, it is a graph comparing the temperature of the upper part LED part, the lower part Termal sheet part, and room temperature using three channels.

The blue curve in this graph 404 represents the highest temperature, which corresponds to the LED portion. Yellow curves indicate low temperatures, corresponding to the thermal sheet. The pink curve represents room temperature.

In the case of the FPCBs 410 and 420 according to the prior art compared with the heat dissipating FPCB 400 according to an embodiment of the present invention, the temperature of the LED 100 in the temperature-time graphs 412 and 422 is constant. It is not maintained but changes unstable. That is, in the case of the FPCB 410 attached to the reinforcement plate, the temperature-time graph 412 shows that the temperature of the LED 100 is changed irregularly in the time period between 400 and 600 seconds.

In the case of the suspend FPCB 420, the temperature-time graph 422 shows a tendency to stabilize after 200 seconds after the initial increase, but the temperature of the heat dissipation FPCB 400 according to an embodiment of the present invention. It shows that the temperature is higher than the temperature-time graph 402.

The graphs 414 and 424 showing the temperature-time graphs 412 and 422 in more detail can be understood with reference to the graphs 402 and 404 described above, so further explanations are provided. It will be omitted.

The temperature characteristics of these FPCBs 400, 410, and 420 are shown in a table for easy understanding, as shown in the following table.

division 0 sec After LED (100) Temperature (℃) 500 sec After LED (100) D temperature (° C) 1000 seconds After LED (100) Temperature (℃) radiation FPCB (400) 21.66 149.35 151.20 Reinforcement plate attachment FPCB (410) 19.47 155.74 154.99 Sus  Attach FPCB (420) 14.97 175.74 176.39

Now, the process of manufacturing FIGS. 2 and 3 will be introduced. 5 is a view illustrating a manufacturing process of a heat dissipation FPCB according to an embodiment of the present invention. That is, FIG. 5 is a flowchart illustrating a process of manufacturing a heat dissipation FPCB according to an embodiment of the present invention. This is described as follows.

The raw material (130 of FIG. 2) is cut out to form a substrate (step S500). The raw material may be an electro-deposited copper foil (ED) or a rolled-annealed copper foil (RA).

Drilling operation is performed on the formed substrate (step S502). That is, a hole is processed to a board | substrate with respect to a target hole.

When the drilling operation is performed, the substrate is plated with copper (step S504). In other words, the copper foil itself is too soft and changeable, and when soldering, the solderability is reduced, thereby plating the exposed copper foil. Plating mainly uses T / L (alloy of tin and lead) or gold (Au) plating.

After copper plating, a process of forming a circuit by bringing D / F (Dry film) into close contact and exposing is performed (step S506). In other words, dry film is adhered to the substrate and the negative film on which the circuit is formed is placed on top and UV rays are applied to form the dry film and the non-solid part. To form a circuit.

Next, C / L provisional execution is performed (step S508). That is, it is a process of attaching the cover layer 320 for protecting the circuit of the copper plate layer (120 of FIG. 3). That is, the polyimide 300 is stacked to prevent the circuit from being exposed to air. Of course, the thermal conductive tape 301 is placed between the polyimide 300 and the copper plate layer 120.

When the temporary welding process is completed, a layup process of stacking interlayer paper, TPX, PET, aluminum plate, etc. between the substrates is performed (step S510). In other words, damage may occur when high temperature heat is applied to the substrate.

After the layup process, a hot press process for attaching the cover layer 320 to the copper plate layer 120 is performed (S512). That is, it is a process of pressing the board | substrate to which the cover layer 320 was welded at high temperature and high pressure, and bonding it.

After the hot press process, a printing process is performed (step S514). That is, the model name, version, layout of the part, etc. of the product are displayed on the substrate.

When the printing process is completed, surface treatment is performed on the substrate (step S516). In other words, it is a process to remove oil, foreign substances, etc. on the surface.

When the surface treatment is completed, a Bare Board Test (BBT) process is performed to check whether the pattern of the circuit formed on the substrate is open or shorted (step S518).

After the BBT process, a process of attaching the heat sink 210 shown in FIG. 2 is performed (step S520). That is, a process of attaching the heat sink substrate 230 prepared by stacking in advance is performed. Therefore, the secondary hot press process, which was performed to adhere the reinforcement plate or sus (SUS), which is conventional, to the substrate, is not required.

In other words, in the conventional method, a process of attaching a thermally conductive bonding sheet to bond a reinforcement plate or sus, a secondary hot press process of necessarily forming at 120 ° C., and then a process of thermally radiating coating are performed. Was required.

When the attachment of the heat sink is completed, a process of processing the appearance and performing a final inspection is performed (steps S522 and S524).

2 to 5 have described the heat dissipation FPCB which is an embodiment of the present invention. In particular, the FPCB of the folder type has been described. However, the present invention is not limited thereto, and other types of FPCBs may be applied to the FPCBs applied to FIGS. 2 to 5.

Although one preferred embodiment of the present invention has been described above with reference to the accompanying drawings, the scope of the present invention is not limited to these embodiments, it will be understood by those skilled in the art that numerous modifications are possible. Accordingly, the scope of the invention should be defined by the appended claims and equivalents thereof.

1 is a cross-sectional view showing a substrate structure of a conventional FPCB.

2 is a cross-sectional view showing a substrate structure of a heat dissipation FPCB according to an embodiment of the present invention.

3 is a cross-sectional view illustrating a detailed substrate structure in which a polyimide and an adhesive layer are laminated on a heat dissipating FPCB of FIG. 2.

Figure 4 is a comparison table comparing the experimental results of the heat dissipation FPCB according to an embodiment of the present invention and the FPCB according to the prior art.

5 is a flowchart illustrating a process of manufacturing a heat dissipation FPCB according to an embodiment of the present invention.

*********** Description of the main signs in the drawings ***********

100: LED 110: Via

120, 121: copper plate layer 130: Flexible Copper Clad Laminate (FCCL) layer

140: bonding sheet layer

150: aluminum layer 200: thermal conductive tape layer

210: heat sink 220: inorganic coating layer

300: polyimide 301: thermally conductive tape layer

310: copper foil 312: polyimide

314: copper foil 320: cover layer

400: heat dissipation FPCB 410: conventional FPCB with reinforcement plate

420: conventional suspend FPCB

402, 412, 422: Temperature-Time Experiment Results Graph

404, 414, 424: graph of experimental results

Claims (6)

delete FCCL (Flexible Copper Clad Laminate) layer in which copper foil is formed on both sides of the polyimide film and the polyimide film, Copper plate layer formed on both sides of the FCCL layer, Including a heat sink substrate attached to one surface of the copper plate layer, The heat sink substrate, With heatsink, An inorganic coating layer formed on one surface of the heat sink, A double-sided thermal conductive tape adhered to one surface of the heat sink in a direction opposite to the inorganic coating layer, The inorganic coating layer is 0 to 60% of silicone resin, 1 to 5% of melamine resin, 1 to 5% of xylene, and 1 to 5% of cyclohexanone. , 10-20% Black Pigment, 20-30% supplement ingredient, wherein the supplement is heat dissipation FPCB which is manganese dioxide (MnO ₂ ). The method of claim 2, The heat sink substrate is a heat dissipation FPCB, wherein the heat sink, the inorganic coating layer and the thermal conductive tape are made in advance as a set. delete Cutting a flexible copper clad laminate (FCCL) to form and drill a flexible printed circuit board (FPCB) substrate; Copper plating the FPCB substrate and attaching a dry film to form a circuit pattern and attaching a cover layer to the FPCB substrate; Hot pressing attaching the cover layer to the FPCB substrate; Attaching a heat sink substrate to one side of the FPCB substrate without an additional hot press process, Attaching the heat sink substrate to one side of the FPCB substrate without a hot press process, Attaching an inorganic coating layer to the heat sink of the heat sink substrate; Attaching a double sided thermal conductive tape to the heat sink, The inorganic coating layer is 50 to 60% of the silicone resin (Silicone resin), 1 to 5% of the melamine resin (Melamine resin), 1 to 5% of xylene (Xylene), 1 to 5% of cyclohexanone (Cyclonhexanone) , 10-20% Black Pigment, 20-30% supplement ingredients, wherein the supplement is manganese dioxide (MnO ₂ ) method for producing a heat dissipating FPCB. The method of claim 5, Attaching an inorganic coating layer to the heat sink of the heat sink substrate; Attaching a double-sided thermal conductive tape to the heat sink is a method of manufacturing a heat dissipating FPCB made prior to fabrication of the FPCB substrate.

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