KR101824001B1

KR101824001B1 - Radiating durable printed circuit board and method for manufacturing the same

Info

Publication number: KR101824001B1
Application number: KR1020150188887A
Authority: KR
Inventors: 김덕년; 이병호; 슈나이더 덕
Original assignee: 주식회사디케이이
Priority date: 2015-12-29
Filing date: 2015-12-29
Publication date: 2018-03-22
Also published as: KR20170078406A

Abstract

A heat-dissipating printed circuit board according to an embodiment of the present invention is a multilayer printed circuit board comprising: a core heat dissipating member including a carbon fiber material; an insulating layer formed to surround the surface of the heat dissipating member, And a thermal via formed through the heat radiation member from the circuit pattern layer and performing thermal conduction between the circuit pattern layer and the exterior.

Description

TECHNICAL FIELD [0001] The present invention relates to a heat-resistant printed circuit board (PCB)

The present invention relates to a heat-resistant printed circuit board having heat dissipation characteristics and a manufacturing method thereof, and more particularly to a heat-resistant printed circuit board having a heat dissipation member at an intermediate layer of a printed circuit board, The present invention relates to a printed circuit board that optimally emits heat generated from a device mounted on a printed circuit board and thereby satisfies heat resistance characteristics.

PCB (Printed Circuit Board) is a circuit connecting part that electrically connects and supports electronic parts and semiconductor by forming a conductive pattern such as copper on an insulating plate such as phenol or epoxy, It is an essential part installed basically in all electronic and information communication equipments such as automobile and aircraft.

PCBs are classified into various types depending on the application, the layer density of the circuit, the processing type, etc. In general, the PCBs are classified into one-sided / double-sided / multilayer boards depending on the number of layers on the wiring circuit surface. Has been adopted.

In the PCB currently used, heat generated from various electronic parts such as semiconductors and LEDs is ultimately discharged through the PCB because the semiconductor and memory chips of the electronic products are mounted on the PCB circuit board and current is used. Accordingly, in the case of electronic parts requiring a high capacity and high light source, research on heat dissipation technology is a key issue determining performance and life span, and research and development on this field is actively proceeding.

Particularly, with the rapid growth of the semiconductor, solar and LED industries, the semiconductor chip size is getting smaller, the capacity and the speed are improved, and the demand for products requiring high density integrated size is increasing, Demand for functional heat-resistant PCB products such as heat-resistant materials and heat-resistant structural designs and new materials to prevent product defects has increased sharply.

Considering heat-resistant PCBs requiring high heat capacity and high heat resistance, FR-4 (composite material of glass fiber and epoxy), which is a conventional PCB insulation layer, has low thermal conductivity (about 0.3 W / m K), the life of the cause of heat generation is lowered.

Therefore, although the demand for metal PCBs using metal materials (Al, Cu, etc.) having excellent thermal conductivity is increasing, in the case of heat-resistant metal PCBs currently being developed and sold, metal materials such as Al or Cu are used, Cracks and weight increase due to the difference in coefficient of thermal expansion are becoming problems with respect to safety.

Recently, the development trend of PCB industry has been demanded of high manufacturing technology (thin plate, high density, functional substrate) due to the trend of high performance, light weight and miniaturization of electronic products, and it is important to secure competitiveness through leading the market .

Particularly, due to the high performance of electronic products and the failure rate of semiconductor and electronic parts due to the temperature generated in LED and semiconductor chip reaches 55% of the total number of failures, PCB and module dimensions Demand for thermal stability is increasing.

In the case of Al or Cu metal base PCB currently adopted in Korea, it is being used with many problems compared to the market demand such as CTE / light weight. That is, hot spot phenomenon due to centralization of heat around the parts, de-lamination due to difference in thermal expansion rate between stacked materials, cracks due to substrate shrinkage / expansion due to temperature change, temperature change of metallic substrate, There is a need for a new method capable of solving the oxidation phenomenon of soldering, in particular, the weight increase due to the specific gravity of the metal material.

Therefore, the object of the present invention is to use the carbon fiber impregnated with the resin excellent in the characteristics in the related items as the core material, as described above. However, the resistance of the carbon fiber strand (Z-axis) thermal conductivity which occurs when using only pure insulating water and the problem of destruction of dielectric layer (interlayer insulation), and to solve the problem of remarkable reduction of z-axis thermal conductivity, have. To achieve this goal, the newly developed core material is more cost competitive than existing solutions.

In order to achieve the above object, a heat-resisting heat-resistant printed circuit board according to an embodiment of the present invention must undergo a special process. A carbon fiber prepreg (PPG) is produced by impregnating a carbon resin with a general resin State), it is necessary to carry out a preliminary process for re-curing it (conversion to a fully cured state). Thus, in the fully-cured carbon fiber in which carbon fiber strands or particles are completed, the breakdown voltage problem can not be caused. In the next step, the circuit pattern and the lamination part of the surface of the copper foil forming the circuit are formed. At this time, the insulation between the circuit pattern and the carbon fiber PPG is required to be 3kV or more and at the same time, a thermal conductivity of 1.5W / Al or Cu base metal PCB can be satisfied. For this purpose, a resin coated Cu (RCC) coated with thermally conductive PPG or thermally conductive resin is inserted in the middle. The use of RCC reduces the cost and costs. In the present invention, resin coated Cu (RCC) coated with a thermally conductive resin is used in order to reduce the overall cost.

A heat-dissipating heat-resistant printed circuit board according to an embodiment of the present invention is a multilayer printed circuit board, comprising: a core heat dissipating member including a carbon fiber material; a heat dissipating member formed to surround the surface of the core heat dissipating member, And a thermal via formed through the heat radiation member from the circuit pattern layer and performing thermal conduction between the circuit pattern layer and the exterior.

According to another aspect of the present invention, there is provided a method of manufacturing a heat-dissipating heat-resistant printed circuit board, comprising: forming carbon fiber prepregs in a semi-hardened state by impregnating a carbon fiber with a general resin; Drying a carbon fiber prepreg and thermally pressurizing it to form a cured carbon fiber; curing the carbon fiber prepreg with an insulating layer and a copper foil

A step of forming a core via-hole in the core insulating member; forming a core via-hole in the core insulating member; forming a core via- And forming a circuit pattern on the insulating layer.

As described above, the heat-dissipating heat-resistant printed circuit board according to the present invention has a thermal conductivity equal to that of the conventional Al and Cu metal PCB, has a low CTE value, and is mounted on a printed circuit board So that the heat generated from the element can be released smoothly.

In addition, the heat-resistant heat-resistant printed circuit board according to the present invention is lightweight compared to a metal PCB and has excellent cost competitiveness. Accordingly, in the development of a heat-resistant PCB, the heat stability and weight- It is possible to improve lifetime and enhance energy efficiency. In addition, the manufacturing method of the heat-dissipating printed circuit board according to the present invention secures the PCB manufacturing technology utilizing the carbon material, which is an embroidering material, and provides it to the LED module, automobile industry, video equipment industry such as TV / monitor, And so on.

1 is a sectional view of a heat-dissipating heat-resistant printed circuit board according to the present invention.
2A to 2E are cross-sectional views illustrating a method of manufacturing a heat-resistant heat-resistant printed circuit board according to the present invention.
3 is a flowchart illustrating a method for manufacturing a heat-resistant heat-resistant printed circuit board according to the present invention.
Fig. 4 shows a table showing the results of the carbon PPG property test.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the following description of the embodiments of the present invention, descriptions of techniques which are well known in the technical field of the present invention and are not directly related to the present invention will be omitted. In addition, detailed description of components having substantially the same configuration and function will be omitted.

For the same reason, some of the elements in the accompanying drawings are exaggerated, omitted, or schematically shown, and the size of each element does not entirely reflect the actual size. Accordingly, the present invention is not limited by the relative size or spacing depicted in the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a printed circuit board and a manufacturing method according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a sectional view of a heat-dissipating heat-resistant printed circuit board according to the present invention. Referring to FIG. 1, a core radiation member 200 serving as a frame is provided in a printed circuit board 100. The core heat dissipating member 200 serves to discharge heat generated in the device mounted on the circuit pattern layer 500 formed on the upper surface of the printed circuit board 100 through the printed circuit board 100.

A circuit pattern layer 500 is formed on the printed circuit board 100. In the circuit pattern layer 500, a circuit pattern for power supply is formed on the element to be mounted thereon.

The core radiation member 200 is surrounded by the insulation layer 300 except for the portion through which the thermal via 600 penetrates.

A thermal via 600 penetrates through the core radiation member 200 from the circuit pattern layer 500 to the core radiation member 200 and the thermally conductive paste is filled in the interior of the thermal via 600. As described above, the thermally conductive paste filled in the thermal via 600 serves to more effectively transfer the heat of the circuit to the outside. Meanwhile, although only two thermal vias 600 are shown in the drawings of this embodiment, the number of the thermal vias 600 is not limited thereto, and may be changed depending on various factors such as the type of circuit elements used.

The inner surface of the insulating layer 300 contacting the core radiation member 200 is a resin layer 320 and the outer surface of the insulating layer 300 is formed of a copper foil 340. The resin layer is composed of a water-soluble paint of polypropylene glycol (heat-radiating PPG).

The core heat dissipation member 200 and the insulating layer 300 may constitute a multilayer printed circuit board in a structure in which the core heat dissipation member 200 and the insulating layer 300 are stacked under the circuit pattern layer 500. Although the core heat dissipating members 200 are illustrated as being stacked twice in the drawing of the present embodiment, the number of the core heat dissipating members 200 is not limited thereto, but may be changed according to the circuit design.

A circuit pattern is formed on the surface of the uppermost copper foil 500. The circuit patterns formed on the upper surface of the printed circuit board 100 may be electrically connected to ground vias formed on the lower surface. To this end, the circuit patterns formed on the upper and lower surfaces of the printed circuit board are connected to each other through the ground vias, and the ground vias may be filled with a paste having electrical conductivity.

In particular, the core heat dissipation member 200 of the present invention is characterized by comprising a carbon fiber material having insulation and thermal conduction. The use of the carbon fiber material as the core radiation member 200 can solve the weaknesses of conventional metal PCB and glass fiber PCB. Specifically, it is possible to design heat-resistant PCBs with a thermal resistance of 288 ° C or higher and achieve a thermal shrinkage expansion of 8ppm / ° C, which improves the performance by more than 200% compared to the domestic 19ppm / ° C (Cu base) , 80% more than existing domestic Cu-based PCB, and 39% more lightweight than Al base PCB. Further, the heat dissipation member based on the carbon fiber material of the present invention can be extended to a substrate for a solar module and a semiconductor package substrate.

In addition, conventionally, a carbon fiber reinforcing material is used to put a copper foil around and keep its shape, while the present invention discloses a different manufacturing method as a technique of manufacturing a carbon fiber prepreg in a fully cured state to manufacture a multilayer substrate .

Hereinafter, the functions of the heat-dissipating heat-resistant printed circuit board and the manufacturing method thereof according to the present invention will be described in detail.

First, the heat generated in the elements mounted on the printed circuit board 100 according to the present invention is emitted with reference to FIG. 1, the heat generated in the device (heat source) is transmitted to the core radiation member 200 through the circuit pattern layer 500 and is formed through the core radiation member 200 Conductive paste of the thermal via 600 and is transferred to the lower portion of the printed circuit board 100. And is also transferred to the side surface of the printed circuit board 100 through the core heat dissipating member 200 to be radiated.

FIGS. 2A to 2F are cross-sectional views illustrating a method of manufacturing a heat-resistant heat-resistant printed circuit board according to the present invention, and FIG. 3 is a flowchart illustrating a manufacturing procedure of a heat-resistant heat-resistant printed circuit board according to the present invention. Hereinafter, a method of manufacturing the printed circuit board of the present invention will be described with reference to FIGS. 2A to 2E and FIG.

First, as shown in FIG. 2A, a carbon fiber prepreg is semi-hardened by impregnating a carbon fiber with a general resin (S410). After the semi-cured carbon fiber prepreg is dried, And the carbon fibers in the cured state are prepared by applying pressure to complete the core radiation member 200 (S420)

That is, as shown in FIG. 2A, a plurality of carbon carbon fiber prepregs are arranged in a vertical direction, then a general resin is impregnated and the core heat-radiating member is completed by high-temperature pressurization.

The copper foil is coated with a heat-dissipating resin and dried to produce a resin-coated copper foil (S430).

Thereafter, the resin-coated copper foil is press-pressed onto the hardened carbon fiber (S440)

Alternatively, as a method different from step S440, a thermosetting resin may be deposited on the surface of the cured carbon fiber, that is, the core heat releasing member 200, and the copper foil may be deposited and then thermally pressed.

The conditions of the thermal pressurization are as follows. The starting temperature of the upper and lower plates of the press is set at 25 to 50 ° C and the temperature is gradually raised. It is appropriate to raise the temperature by 5 to 20 ° C every 5 minutes, and at 50 to 50 ° C Minute to 60 minutes. It also includes the process of gradually lowering the temperature at the highest temperature. At this time, the process of lowering the temperature is preferably between 2 [deg.] C and 5 [deg.] C per minute, and a pressure of 10 to 30 kgf / cm2 is suitable. Also, the total press time for heat press is preferably about 60 to 120 minutes.

Resin coated copper (RCC) can be used as the heat dissipating resin. By doing so, it is possible to prevent the possibility of penetration due to carbon fiber strands or particles in the completely hardened carbon fiber in the future lamination process, and to prevent the breakdown voltage problem. The manufacturing method of successively curing the insulating layer and the copper foil on the carbon fiber PPG in this way is a new manufacturing method which is different from the general batch curing manufacturing method and can satisfy the withstand voltage characteristics of the circuit pattern.

The next step is to laminate the carbon fiber PPG with the circuit pattern on the copper foil surface forming the circuit. In the lamination process, the insulation between the circuit pattern and the conductive carbon fiber PPG should be 3kV or more, and at the same time, a thermal conductivity of 1.5W / mK or more must be realized to satisfy the characteristic value pursued by the conventional Al or Cu base metal PCB. For this purpose, resin coated Cu (RCC) coated with thermally conductive PPG or thermally conductive resin is inserted between the circuit pattern and the carbon fiber PPG. The use of RCC reduces the cost and costs. In the present invention, resin coated Cu (RCC) coated with a thermally conductive resin is used in order to reduce the total cost.

That is, the RCC (insulating layer) formed of the thermally conductive resin and the copper layer made of the copper foil are integrally formed on the upper and lower surfaces of the core radiation member 200, that is, the RCC coated copper foil is bonded. At this time, the insulating layer is brought into close contact with the surface of the core radiation member 200, and the copper layer appears on the surface.

Here, the core radiation member 200 is made of a carbon fiber member having excellent conductivity, rigidity and low coefficient of thermal expansion for optimal heat dissipation.

Table 1, which shows characteristic values of the material of the PCB core, indicates that the carbon fiber has better thermal conductivity than copper, CIC, glass fiber (CCL) and aluminum, and has a thermal expansion index (IN-PLANE CTE) Rigidity and light weight of the heat dissipating member.

MATERIAL Thermal
Conductivity
(W / mK) IN-PLANE CTE
(ppm / DEG C) Tensile Modulus (N / mm) (Rigidity) Density (Weight) (g / cc) Carbon Composite 75 to 250 1 to 5 11 to 40 1.65 to 1.75 Heavy Copper 385 to 400 17 to 9 12 to 16 8.90 Copper-Invar-Copper (CIC) 20 to 30 5 to 6 18 to 19 9.90 CCL (glass fiber) 0.3 16 to 20 3.5 to 4.5 1.6 to 1.8 Aluminum 5052 150 25 3.76 2.70

Next, the core dissipating member 200 formed by the above-described method is cut to an appropriate size, and the required thermal via 600 and the ground via 700 are punched as shown in FIG. 2B.

The perforation of the thermal via 600 and the ground via 700 may be performed through a drilling operation, or through a process such as exposure, development, or etching. That is, after the upper surface and the lower surface of the core radiation member 200 are flattened, a dry film is applied to the upper and lower surfaces of the core radiation member 200 and vias are formed through typical exposure, development, . After that, the dry film remaining in the center portion is removed, and the surface of the substrate is roughened through an oxidation process.

In this state, the thermal via 600 penetrates through the portion of the core radiation member 200 where the circuit pattern layer 500 is to be formed, and the thermal via 600 is punched. The thermal via 600 is for conducting the heat generated from the elements mounted on the circuit pattern layer 500 to the lower portion of the printed circuit board 100 and discharging the heat to the outside.

Then, as shown in FIG. 2C, the thermal via 600 is filled with the thermally conductive paste. Where the thermally conductive paste is positioned within the thermal via 600 through paste printing, cure, and desmear processes.

After the thermally conductive paste is filled in the thermal via 600 as described above, the ground vias 700 are punched again. That is, the insulating layer filled in the ground vias 700 is removed.

After the ground vias 700 are again punched, a circuit pattern is formed. First, as shown in FIG. 2D, copper plating (c) is performed on the upper and lower surfaces of the printed circuit board 100 and the ground vias 700. The upper surface of the printed circuit board 100 and the ground vias 700 are coated with copper plating c by the copper plating c and the upper and lower surfaces of the printed circuit board 100 are electrically connected to the ground vias 700 And are electrically connected to each other.

Then, the plating process is performed such that the plated surface is leveled, the dry film is placed on the plated surface, and a circuit pattern is formed through exposure, development and etching processes. Then, as shown in FIG. 2E, the copper plating (c) is removed from the etched portion of the copper plating to expose the insulating layer.

Then, a solder resistor is filled / coated on a portion of the upper and lower surfaces of the printed circuit board 100 and the ground vias 700, and dried and then a wire bonding pad is formed on the upper surface through exposure and development processes. 800). Then, the pad portion is oxidized. Next, the pad portion is plated with gold. That is, when the plating process is performed on the pad portion in the oxidized state, the thin film generated by the oxidation in the previous process is removed and gold plating is performed on the surface. At this time, the circuit pattern layers 500 and 25 are provided with a peelable, which is a kind of masking material. The reason for using the filler in this way is that there is a problem that adhesion between the element and the circuit pattern is not ensured if the gold plating process is performed on the circuit pattern layer 500. [

Finally, when the filler P is removed, the printed circuit board 100 is completed as shown in FIG. 2A.

Meanwhile, FIG. 4 is a table showing test results of the physical properties of the cured carbon fibers shown in FIG. 2A, and FIG. 2F shows a cross-sectional shape of the finished product. For example, in the finished product PCB of the present invention, the resin is impregnated at the center when cut, and the cured carbon fiber 200 is seen, and the insulating layer 300 has heat insulating properties on both sides.

As described above, the heat-dissipating heat-resistant printed circuit board according to the present invention has a thermal conductivity equivalent to that of existing Al and Cu metal PCBs, has a low CTE value, and is mounted on a printed circuit board The heat generated from the element can be smoothly discharged.

Particularly, in the present invention, the carbon fiber having excellent properties is impregnated into the resin to be used as a core material. In this case, the problem of breakdown of voltage resistance characteristics (interlayer insulation) (Z-axis) thermal conductivity which is generated when a semiconductor device is used, and thus can be effectively used in various electronic products fields.

In addition, since the heat-resistant heat-resistant printed circuit board according to the present invention has lightweight characteristics and excellent cost competitiveness, it is possible to improve the lifetime of LED products and semiconductor chip products by securing thermal stability and weight- Energy efficiency can be improved. In addition, the method of manufacturing a heat-dissipating printed circuit board according to the present invention secures PCB manufacturing technology using carbon material, which is an unprocessed material, and can be applied to various industries such as LED module, automobile industry, Do.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. , And are not intended to limit the scope of the present invention. It is to be understood by those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments described herein.

100: printed circuit board 200: core radiation member
300: insulating layer 400: copper foil
500: circuit pattern layer 600: thermal via
700: Ground Via 800: Ball Pad

Claims

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Impregnating a carbon fiber with a resin to form a semi-hardened carbon fiber prepreg;
Drying the carbon fiber prepreg in the semi-cured state and thermally pressurizing the carbon fiber prepreg to form a hardened carbon fiber to form a cured core radiation member;
Applying a heat dissipation resin to the copper foil and drying the copper foil to produce a copper foil coated with the heat dissipation resin;
Thermally pressing the copper foil coated with the heat-dissipating resin onto the surface of the core radiation member; Made of
The step of thermally pressing the copper foil coated with the heat dissipating resin on the surface of the core heat dissipating member is performed by a heat press,
Determining the starting temperature of the upper and lower plates of the press at 25 ° C to 50 ° C;
Raising the temperature between 5 ° C and 20 ° C every 5 minutes to raise the temperature to a maximum temperature between 180 ° C and 250 ° C;
Maintaining the maximum temperature for 50 minutes to 60 minutes;
Lowering the temperature by 2 to 5 DEG C per minute
The heat-dissipating resin-coated copper foil is thermally pressed on the surface of the cured core heat-releasing member through a press, so that carbon fiber strands or particles contained in the core heat- And preventing the breakdown voltage problem by blocking the penetration possibility at the source.

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