JP2788779B2 - Material board for circuit board - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a base plate used for an electronic circuit board such as a computer and a word processor.

[Prior art] Conventionally, as a material plate of an electronic circuit board, a sheet (prepreg) in which a glass cloth impregnated with an epoxy resin or the like, a polyimide film, a polyester film, or the like is used as an insulating layer, and the surface thereof is electrically conductive. 18-75μ as layer
A copper-clad laminate obtained by thermocompression bonding a copper foil having a thickness of about m is widely used.

In these copper-clad laminates, a special surface treatment (plasma treatment or the like) is applied to the surface of the polymer material layer in order to secure adhesion between the metal copper foil and the polymer material layer (insulating layer). In general, the surface of a copper foil is electrochemically roughened.

In addition, in order to improve the adhesion, an attempt has been made to form an anchor layer of a different metal such as chromium or nickel between the polymer material layer and the copper layer.

[Problems to be Solved by the Invention] However, in the conventional circuit board material plate as described above, in a method of performing a surface treatment on a bonding surface of a polymer material layer or a copper layer, sufficient adhesion between the two is not achieved. There was a problem that it was not secured.

That is, when manufacturing a circuit board, various chemical and chemical processes are performed in etching for forming a circuit, chemical treatment for applying surface plating such as tin, physical processing such as drilling, and heat treatment such as solder fusing. Although a physical load is applied to the material plate, the adhesion between the polymer material layer and the copper layer is insufficient in the conventional circuit board material plate, so that the polymer material layer and Peeling is likely to occur between copper layers. In addition, there is a risk that peeling may occur not only during the manufacturing process, but also due to a heating process at the time of mounting the electronic component or a change over time after being incorporated into the electronic device. Such a problem of the adhesion between the polymer material layer and the copper layer has become a more and more serious problem from the viewpoint of reliability in today's increasingly fine circuits and high-density packaging.

On the other hand, in the method of providing an anchor layer of a dissimilar metal such as chromium or nickel between the polymer material layer and the copper layer, although a certain degree of adhesion is ensured, etching cannot be performed under the same conditions as when only copper foil is used. In addition, the anchor layer etching process becomes complicated, and special wastewater treatment equipment is required, which is not practical.

The present invention has been made in view of such a point,
It is an object of the present invention to provide a circuit board material plate that has excellent adhesion between a polymer material layer and a copper layer and that can easily form a circuit.

[Means for Solving the Problems] A circuit board blank according to the present invention is a circuit board blank in which a copper layer is supported by a polymer material layer. A material plate for a circuit board, wherein a vapor deposition layer is formed, and the copper layer is formed on a surface of the copper nitride sputter vapor deposition layer. Things.

In the present specification, for convenience, the material “plate” is used for a circuit board, but it goes without saying that the material includes not only a material for a rigid circuit board but also a material for a flexible circuit board.

[Function] In the circuit board material plate of the present invention, the copper nitride layer provided between the polymer material layer and the copper layer functions to enhance the adhesion between the two, and can be used for tin plating or the like when forming the circuit board. The adhesion is not greatly reduced by various chemical treatments, including chemical treatments under severe conditions, heat treatment, and physical impact in displacement plating. In addition, the copper nitride layer can be favorably etched under the same conditions as the copper layer thereon, and the existing equipment can be used for drainage treatment as it is.

In order to manufacture the circuit board material plate of the present invention, first, a surface of a polymer material layer composed of a glass-epoxy sheet, a polyimide film, a polyester film, an ethylene / fluoroethylene copolymer film, or the like is applied to a surface of 1,000 mm or less (in particular, (Preferably 5 to 300 °). Normally, this material plate is bent to a radius of curvature of about 100 mm and wound up, so in this case to avoid the occurrence of cracks
1000 mm or less is desirable. Further, in order to perform uniform sputtering of copper nitride, 5 ° or more is required, but if it is 300 ° or more, the material may curl due to heat during sputtering.

This copper nitride layer is formed by a ceramic film forming method such as vapor deposition, CVD (chemical vapor deposition), or sol-gel method. In particular, reactive sputtering using copper as a target and nitrogen gas as a carrier gas is used. It is preferable to form by an evaporation method. In this case, when a polyimide film is used for the polymer material layer, better results can be obtained. Also,
By subjecting the surface of the polymer material layer to plasma treatment with nitrogen gas, oxygen gas, argon gas, or the like, the adhesion of the copper nitride layer can be increased. At this time, if a plasma treatment of nitrogen gas is employed, the carrier gas becomes the same, so that a vacuum-based in-line process can be integrated with the reactive sputter deposition method for forming the copper nitride layer.

Next, a copper layer is formed on the copper nitride layer formed as described above by a vapor deposition method, a plating method, or a combination thereof. It is desirable to perform electroplating accordingly. Further, by subjecting the surface of the copper nitride layer to a plasma treatment using a nitrogen gas, an oxygen gas, an argon gas, or the like, the adhesion between the copper nitride layer and the copper layer can be improved.

Embodiments FIGS. 1A to 1D are cross-sectional views showing a process for manufacturing a circuit board blank according to an embodiment of the present invention.

In this embodiment, a 50 μm-thick polyimide film 1 (trade name: Kapton 200H, manufactured by Dupont, USA) as a polymer material layer was used, and after the surface of the polyimide film 1 was subjected to argon plasma treatment (first (A), a copper nitride layer 2 of 200 ° was provided by reactive sputtering using copper as a target and nitrogen as a carrier gas (FIG. 1 (b)). Thereafter, a 1 μm copper layer 3 is formed on the copper nitride layer 2 by sputtering using argon as a carrier gas.
(FIG. 1 (c)). Then, electrolytic plating is further performed thereon, and the entire thickness of the copper layer 3 formed by the sputtering method and the copper layer 4 formed by the electrolytic plating is set to 35 μm, and a circuit board material plate as shown in FIG. Produced.

Next, a peel test between the polyimide film 1 and the copper layers 3 and 4 was performed on the circuit board material plate manufactured as described above, and a peel strength of 1.8 kg per 10 mm width was obtained.

Also, as a comparative product, a peel test was performed on a circuit board material plate having the same configuration as that of the above-described example product except that the copper nitride layer was not formed, and 0.8 kg per 10 mm width was half that of the example product. Only the following peel strengths were obtained.

A circuit pattern having a conductor width of 50 μm and a conductor pitch of 100 μm was formed on the obtained circuit board material plate by photolithography. In this step, using an alkali developing type resist, perform development processing with 1.1.1 trichloroethane, perform etching of copper and copper nitride with an aqueous ferric chloride solution, and perform stripping processing of the resist with acetone. Acid chloride with hydrochloric acid, hydrochloric acid and tetrafluoroboric acid
Electroless tin plating was performed using a tin aqueous solution as a main component. During this step, no peeling occurred between the polyimide film and the conductor. In addition, 50
A sticking / peeling test of the pressure-sensitive adhesive tape corresponding to 0 g / cm was performed, but no peeling occurred between the two.

On the other hand, for comparison, when the same process was performed on a circuit board material plate manufactured without a copper nitride layer interposed,
Partially peeling occurred between the polyimide and the conductor during the process of forming the circuit pattern, and the conductor was completely peeled off from the film in the adhesion / peeling test of the adhesive tape.

[Effect of the Invention] As described above, in the circuit board material plate of the present invention, the copper nitride layer is provided between the polymer material layer and the copper layer. Adhesion is less likely to decrease even in post-processing such as chemical processing, physical processing, heat treatment, and component mounting in forming a circuit, and peeling of the polymer material layer and the copper layer hardly occurs.

In addition, the circuit board material plate of the present invention can be etched under the same conditions as conventional products using only a copper layer, and there is no need to newly perform a special drainage treatment. There is also an advantage that a circuit can be easily formed.

The circuit board material plate of the present invention, which has excellent adhesion between the insulating layer (polymer material layer) and the conductor layer (copper layer), has great industrial value today, as circuits are becoming more densely multilayered and densely packed. It is.

[Brief description of the drawings]

1 (a) to 1 (d) are cross-sectional views showing steps of manufacturing a circuit board blank according to an embodiment of the present invention. [Description of Signs of Main Parts] 1... Polyimide film (polymer material layer) 2... Copper nitride layer 3... Copper layer by sputtering method 4.

Continuation of the front page (72) Inventor Akira Stockmoto 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (56) References JP-A-2-301907 (JP, A) JP-A-56- 142869 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H05K 3/00, 3/10-3/24, 3/38 B32B 15/08 C23C 14/00-14/58

Claims (1)

(57) [Claims] In a circuit board material plate in which a copper layer is supported by a polymer material layer, a sputter-deposited layer of copper nitride is formed on a surface of the polymer material layer, and A material plate for a circuit board, wherein the copper layer is formed on a surface.