KR100852730B1 - Method for preventing oxide layer formation in via hole and through hole working of circuit - Google Patents

Abstract

A method for preventing formation of an oxide layer in processing a via hole and a through hole of a circuit board is provided to minimize a plating error of an interface by closely adhering a copper plated layer to a flexible copper clad laminate during a plating process for formation of the copper plated layer. A method for preventing formation of an oxide layer in processing a via hole and a through hole of a circuit board includes the step of: processing the via hole or the through hole while offsetting a photoelectric effect by supplying an electron and a cation through an ionizer or a plasma generation device(100) to a portion where the hole is processed by a UV laser in processing the via hole or the through hole on a flexible copper clad laminate(10) by using the UV laser.

Description

METHOD FOR PREVENTING OXIDE LAYER FORMATION IN VIA HOLE AND THROUGH HOLE WORKING OF CIRCUIT}

The present invention relates to the manufacture of a flexible circuit board, and more particularly, to the inside of the via hole or through hole according to the occurrence of the photoelectric effect during the via hole or through hole processing through laser drilling on the copper foil laminated film that is the material of the flexible circuit board. The present invention relates to a method of preventing oxide layer generation during via hole or through hole processing of a circuit board to improve the quality of a flexible circuit board manufactured by preventing the formation of an oxide layer.

Flexible Printed Circuit Board (FPCB) is an electronic component developed as electronic products become smaller and lighter, and is widely applied as a core component of all electronic products because of its excellent workability, heat resistance, chemical resistance, and heat resistance. .

As shown in FIG. 1, the flexible circuit board mainly uses a copper clad laminated film (FCCL) 10 having a structure in which copper (Cu) is laminated on a polyimide (PI) film as a material of a substrate. Copper foil laminated film after the process of drilling the through-hole 20 for inter-circuit conduction or inter-circuit conduction and component mounting in the copper foil laminated film 10, and the drilling process of processing the via hole or through-hole 20 ( 10) forming a copper plating layer 30 on one side or both sides, and laminating a photosensitive film (DFR; Dry Film Photoresist) 40 on the copper foil laminated film 10 on which the copper plating layer 30 is formed. It manufactures by the process of exposing and etching and forming a circuit pattern.

At this time, the processing of the via hole or through-hole 20 is a general technique using a laser, the via hole (BVH) or through-hole (PTH) of more than 100um usually uses a carbon dioxide laser, via holes or through less than 100um Hall mainly uses UV lasers.

However, in manufacturing a conventional flexible circuit board, copper (Cu) and poly of the copper laminated film 10 are contacted as the UV laser beam is contacted when drilling via holes or through holes in the copper laminated film 10 using a UV laser. Due to the melting of the mid PI, a via hole or a through hole is formed. In this case, as shown in FIG. 2, a via hole or a through hole is formed by melting copper (Cu) and polyimide (PI) due to contact of a laser beam. Carbon dioxide (CO ₂ ) and oxygen (O ₂ ) are formed in the atmosphere and the copper (Cu) of the copper clad laminated film 10 having metallicity is brought into contact with the short wavelength (1 to 400 nm) of the UV laser photoelectric effect ) is generated by emitting electrons and charged with Cu ⁺ or Cu ^2+, Cu ⁺ or Cu ²⁺ which is charged by the photoelectric effect is CuO inside the via hole or a through-hole in combination with the CO ₂ and O ₂ composition in the atmosphere and the oxide layer 50 of CuCO ₃ Was the problem of formation, there is a problem in that the generation of Cu ⁺ or Cu ²⁺ and CO ₂ when combined with by-product carbon (C) the composition into the atmosphere.

Therefore, when the copper plating layer 30 is formed by electroplating on the copper foil laminated film 10 to form a circuit pattern and conduction, as shown in the interface observation photograph of FIG. There was a problem in that the lifting phenomenon caused by the formation of the oxide layer in the inter-interface portion of the copper plating layer formed by plating.

In addition, as a result of analyzing the weight of elements and elements present in the interface portion after copper plating, it shows that 68.82% by weight of copper (Cu), 4.51% by weight of oxygen (O), 26.67% by weight of carbon (C). It contains a large amount of carbon in adults and a marked lack of copper.

Accordingly, it is pointed out as a factor that lowers the quality of the flexible circuit board, such as poor conduction and resistance increases due to a poor interface portion inside the via hole or through hole.

The present invention is a flexible circuit board manufactured by preventing the formation of an oxide layer formed in the via hole or the through-hole according to the occurrence of the photoelectric effect during the processing of the via hole or through hole through the UV laser drilling in the copper foil laminated film that is the material of the flexible circuit board An object of the present invention is to provide a method of preventing oxide layer generation during via hole or through hole processing of a circuit board to improve the quality of the circuit board.

That is, the present invention cancels the photoelectric effect generated during the processing of the via hole or the through hole by UV laser drilling, thereby preventing the formation of an oxide layer inside the hole to be processed on the copper-clad laminate film, thereby interfacing the plating process for forming the copper plating layer thereafter. It is to improve plating quality as well as product quality by eliminating plating defects of parts.

The present invention is a process of drilling via holes or through holes using a UV laser to a copper foil laminated film having a structure in which copper is laminated on a polyimide film, and a copper foil laminated film having a via hole or through hole formed by the UV laser processing. In the manufacturing process of a flexible circuit board comprising a step of forming a plating layer,

When processing via holes or through holes in the copper-clad laminated film using the UV laser, the electrons (e-) and cations (O ²⁺ ) using an ionizer or a plasma generator are supplied to the hole processing by the UV laser. The via hole or through hole processing is performed while canceling the photoelectric effect.

The present invention has an effect of canceling the photoelectric effect of the electron emission generated by the contact of light and metal during the processing of the via hole or through hole by UV laser drilling, and thus an oxide layer inside the via hole or through hole processed on the copper-clad laminated film. It is possible to effectively prevent the formation of the copper foil, and then the copper plating layer can be formed to be in close contact with the copper plating layer to form a copper plating layer on the copper foil laminated film, thereby eliminating the plating defect at the interface portion and improving the plating quality. In addition, it is possible to improve the overall quality of the product according to the circuit board manufacturing.

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

As shown in FIG. 1, the method for preventing the formation of an oxide layer during the processing of a via hole or a through hole of a circuit board according to the present invention is performed on a copper laminated film 10 having a structure in which copper (Cu) is laminated on a polyimide (PI) film. Drilling a via hole or through hole 20 using a laser, and forming a copper plating layer 30 on the copper-clad laminated film 10 having the via hole or through hole 20 formed by the UV laser processing. In the manufacturing process of the flexible circuit board,

Hole processing is performed by UV laser when processing via holes or through holes in the copper foil laminated film 10 using the UV laser, as shown in FIG. 4, the ionizer or the plasma generating apparatus 100. It is configured to perform via hole or through hole processing while supplying electrons (e−) and cations (O ²⁺ ).

That is, when processing the via hole or through hole in the copper foil laminated film 10 using a UV laser, as the UV laser beam contacts, melting of copper (Cu) and polyimide (PI) is performed to form a via hole or through hole. When the UV laser beam is brought into contact with metallic copper, copper is started to be charged with Cu ⁺ or Cu ²⁺ by electron emission due to the photoelectric effect. In the present invention, the ionizer or the plasma generator 100 is used as a hole processing part. By artificially supplying a large amount of electrons and cations by using electrons, the electrons are emitted and combined with Cu ^{+ on the} surface of the charged copper, which acts to shield the deepening of the charging phenomenon while canceling the photoelectric effect. (Cu ⁺⁾ is geotkka ions offset the binding force which easily combine with CO ₂ and O ₂ in the air, while generating a by-product of electronegative carbon (C) according to the coupling It is the functional block.

Accordingly, after the via-hole or through-hole laser drill processing using the ionizer or the plasma generating apparatus 100 according to the present invention, the copper plating layer for the circuit pattern and the conduction is formed on the copper-clad laminated film 10 by electroplating. As shown in the interface observation photograph in FIG. 5, it is shown that mutually interfacial portions of copper plating layers formed by copper plating and electroplating of copper foil laminated films are closely connected to each other. It has been shown that the problem of lifting caused by the formation of the oxide layer is improved.

In addition, as a result of analyzing the weight of elements and elements present in the interface portion after copper plating, 97.63% by weight of copper (Cu) and 2.37% by weight of oxygen (O) are distributed, and the specific gravity of copper is almost entirely included. Oxygen is reduced and does not contain non-metallic carbon.

Therefore, according to the present invention, it is possible to suppress the generation of the oxide layer generated by the photoelectric effect during the processing of the via hole or the through hole by the conventional UV laser, and the internal copper lamination of the via hole or the through hole during the plating process performed after the via hole or the through hole processing. It is to provide an effect of improving the defect of the lifting phenomenon on the interface portion between the copper layer and the copper plating layer on the film and a quality improvement effect that can greatly reduce the resistance of the interface portion.

1 is a view schematically showing a manufacturing process of a flexible circuit board according to an embodiment of the prior art.

2 is a view showing for explaining a laser drill process in the manufacturing of a conventional flexible circuit board.

Figure 3 is a photograph observing the interface state after electroplating according to the prior art.

Figure 4 is a view showing for explaining the laser drilling process in the manufacture of the circuit board according to the present invention.

5 is a photograph observing the interface state after the electroplating according to the present invention.

Claims (1)

Forming a copper plating layer on a copper foil laminated film in which via holes or through holes are formed by drilling a via hole or through hole using a UV laser to a copper foil laminated film having a structure in which copper is laminated on a polyimide film, and by the UV laser processing. In the manufacturing process of a flexible circuit board comprising the step of: When processing via holes or through holes in the copper-clad laminated film using the UV laser, the electrons (e-) and cations (O ²⁺ ) using an ionizer or a plasma generator are supplied to the hole processing by the UV laser. A method of preventing the formation of an oxide layer during a via hole or through hole processing of a circuit board, characterized in that the via hole or through hole processing is performed while canceling the photoelectric effect.

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