Adhesiveless Copper Clad Laminates And Method For Manufacturing Thereof

Abstract

The present invention provides adhesiveless copper clad laminates, which does not have defects on a copper film part due to a pin hole generated at the time of forming a base metal layer on an insulating film by dry plating process, has excellent adhesion between the insulating film and the base metal layer and corrosion resistance, and has a copper film layer having high insulation reliability, and provides a method for manufacturing such adhesiveless copper clad laminates. In adhesiveless copper clad laminates according to the present invention provided by forming a base metal layer directly at least on one plane of an insulating film without having an adhesive in between, and then by forming a copper film layer on the base metal layer, the base metal layer having a film thickness of 3 to 50 nm is formed by dry plating method and mainly contains a chrome-molybdenum-nickel alloy wherein the chrome ratio is 4 to 22 weight %, the molybdenum ratio is 5 to 40 weight %, and the balance is nickel.

Description

TECHNICAL FIELD [0001] The present invention relates to adhesiveless copper clad laminates and a method for manufacturing thereof, and more particularly to adhesiveless copper clad laminates in which a nickel-chrome-molybdenum base metal layer (a seed layer) is formed on an insulating film by a dry plating method and a copper film layer is then formed on the base metal layer, and which has high adhesion and corrosion resistance, and has the copper film layer with high insulation reliability, and to a method for manufacturing thereof. BACKGROUND ART [0002] In general, substrates used to manufacture flexible wiring substrates are roughly divided into adhesive copper clad laminates in which a copper foil serving as a conductor layer is bonded together on an insulating film by using an adhesive (see, e.g., Patent Document 1), and adhesiveless copper clad laminates in which a copper film layer serving as a conductor layer is directly formed on the insulating film by a dry plating method ...

AI Technical Summary

Benefits of technology

[0033] According to the method for manufacturing adhesiveless copper clad laminates of the present invention, in adhesiveless copper clad laminates provided by forming a base metal layer directly at least on one plane of an insulating film without having an adhesive in between and then by forming a copper film layer on the base metal, it is possible to obtain the adhesiveless copper clad laminates characterized by having the base metal layer with a film thickness of 3 to 50 nm formed on the insulating film by a dry plating method and the copper film layer with a film thickness of 10 nm to 35 μm formed on the base metal layer, the base metal layer mainly containing a chrome-molybdenum-nickel alloy in which a chrome ratio is 4 to 22 weight %, a molybdenum ratio is 5 to 40 weight %, and the balance is nickel.

[0034] Furthermore, according to the adhesiveless copper clad laminates of the present invention, a reduction in heat-resisting peel strength can be avoided since the base metal layer contains chrome, corrosion resistance and insulation reliability can be improved since the base metal layer contains molybdenum, and hence using the adhesiveless copper clad laminates can efficiently obtain a flexible wiring substrate that has excellent adhesion and corrosion resistance and has a defect-free reliable wiring portion with a narrow width and a narrow pitch, whereby an effect of the adhesiveless copper clad laminates is extremely large.

[0035] 1) Adhesiveless Copper Clad Laminates

[0036] adhesiveless copper clad laminates according to the present invention is adhesiveless copper clad laminates provided by forming a base metal layer directly at least on one plane of an insulating film without having an adhesive in between and forming a copper conductor layer with a desired thickness on the base metal layer, and is characterized in that the base metal layer having a film thickness of 3 to 50 nm is formed on the insulating film by a dry plating method and a copper film layer is formed on the base metal layer, the base metal layer mainly containing a chrome-molybdenum-nickel alloy in which a chrome ratio is 4 to 22 weight %, a molybdenum ratio is 5 to 40 weight %, and the balance is nickel.

[0037] Adopting the above-described structure can obtain the adhesiveless copper clad laminates that has excellent adhesion and corrosion resistance and has a copper conductor layer with high insulation reliability formed thereon.

[0038] Here, as a film thickness of the base metal layer mainly containing the chrome-molybdenum-nickel alloy obtained by the dry plating method, a range of 3 to 50 nm is preferable. When the film thickness is smaller than 3 nm, a problem of, e.g., a considerable reduction in wiring peel strength occurs because an etchant used when performing wiring processing infiltrates to thereby raise a wiring portion, and hence this film thickness is not preferable. Additionally, when the film thickness exceeds 50 nm, effecting etching is difficult, and hence this film thickness is not preferable.

Problems solved by technology

Therefore, when etching is carried out till electrical insulating properties are assured between wiring portions, a wiring pitch width becomes too wide, and hence there is a limit in narrowing a pitch of the wiring portion on a wiring substrate as long as adhesive copper clad laminates in which a generally conventionally used copper foil having a thickness of 35 μm is bonded to an insulating film through an adhesive is utilized.

However, since such a thin-walled copper foil has small rigidity and poor handling properties, there is adopted a method of temporarily bonding a reinforcing material such as an aluminum carrier to the copper foil to increase the rigidity, then bonding the copper foil to the insulating film, and further removing the aluminum carrier, but this method takes trouble and time and has a problem of poor operability and productivity.

Further, such a thin copper foil has a problem in a manufacturing technology, e.g., an increase in film defects due to unevenness in film thickness or occurrence of pin holes or cracks, the copper foil itself becomes difficult to be manufactured as a thickness of the copper foil is reduced, and a manufacturing price is increased, thereby losing cost merits of the adhesive flexible wiring substrate.

In particular, a demand for a wiring substrate having a wiring portion with a narrow width and a narrow pitch that cannot be manufactured unless a copper foil having a thickness of ten-odd μm or below or approximately several μm is used has been recently increased, and a wiring substrate using adhesive copper clad laminates has the above-explained technical problem as well as a manufacturing cost problem.

However, according to this method, an exposed part of the insulating film due to a pin hole can be assuredly eliminated to some extent but, on the other hand, it is known that a plating liquid, its preprocessing liquid or the like used in electroless copper plating processing enters a space between the insulting film and the base metal layer from already formed large and small various pin hole parts, and this may possibly becomes a factor that obstructs adhesion properties of the base material layer and adhesion properties of a conductor layer subsequently formed by electrolytic copper plating, and hence this method is not a sufficient countermeasure.