Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
1999-12-08
2001-06-05
Lam, Cathy (Department: 1775)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S901000, C174S250000, C174S261000
Reexamination Certificate
active
06242079
ABSTRACT:
TECHNICAL FIELD
This invention relates to a printed wiring board, and more particularly to a multilayer printed wiring board capable of preventing the peeling of interlaminar resin insulating layer even in the heating or under heat cycle condition and ensuring the connection reliability of a via-hole portion. Furthermore, the invention relates to a printed wiring board having an excellent adhesion property between a conductor circuit for solder pad and a solder resist layer.
BACKGROUND ART
Recently, so-called buildup multilayer wiring board is noticed from a demand for high densification of a multilayer wiring board. The buildup multilayer wiring board is manufactured by a method disclosed, for example, in JP-B-4-55555. That is, an insulating material made of a photosensitive adhesive for electroless plating is applied onto a core substrate having conductor circuits, dried, exposed to a light and developed to form an interlaminar insulating layer having an opening for via-hole. Then, the surface of the interlaminar insulating layer is roughened by a treatment with an oxidizing agent or the like and a plating resist is formed on the resulting roughened surface and thereafter portions not forming the resist are subjected to an electroless plating to form a two-layer conductor circuit pattern including a via-hole. Such steps are repeated plural times to obtain a multilayered buildup wiring board.
And also, a multilayer technique using so-called RCC (RESIN COATED COPPER) is watched as the buildup multilayer printed wiring board. This technique is a technique wherein RCC is laminated on a circuit board and copper foil is etched to from an opening in a position for the formation of a via-hole and a laser beam is irradiated to the opening portion to remove a resin layer and the opening portion is plated to form a via-hole.
Furthermore, there is developed a multilayer technique wherein one-sided circuit boards having a conductive substance filled in a through-hole are laminated through an adhesive layer as described in JP-A-9-36551.
In such a multilayer printed wiring board, a surface of an underlayer conductor circuit is roughened for improving an adhesion property between the surface of the underlayer conductor circuit and the interlaminar resin insulating layer. The thus formed roughened layer can improve the adhesion property in a via-hole portion. Such a roughening is carried out by graphitization-reduction treatment, etching with sulfuric acid-hydrogen peroxide, plating of copper-nickel-phosphorus needle alloy and the like.
The printed wiring board is provided on its surface layer with solder bumps and connected to an IC chip through the solder bumps. In this case, a solder resist layer is formed in the printed wiring board to protect the conductor circuit for solder pad as a surface layer and so as not to fuse solder bumps with each other.
In the printed wiring board, the surface of the conductor circuit is subjected to a roughening treatment for enhancing the adhesion between the conductor circuit for solder pad and the solder resist layer. As the roughening treatment of the conductor circuit, there are used graphitization-reduction treatment, etching with sulfuric acid-hydrogen peroxide, plating of copper-nickel-phosphorus needle alloy and the like.
However, it is known that when the via-hole is formed by plating, the plated film hardly adheres to the roughened layer and it is apt to cause the peeling of via-hole conductor. For this end, it becomes common sense that although the roughened layer is formed on the surface of the underlayer conductor circuit in portions contacting with the interlaminar resin insulating layer, the roughened layer is removed in portions contacting with the via-hole conductor (see, for example, JP-A-3-3298).
PROBLEMS TO BE SOLVED
Even when the surface of the underlayer conductor circuit connecting to the via-hole conductor is flattened, however, there may be caused the peeling of the via-hole conductor from the underlayer conductor circuit in the heating or under heat cycle condition.
In order to solve this problem, it is favorable to improve the adhesion property between the underlayer conductor circuit and the via-hole conductor. However, when the surface of the underlayer conductor circuit is roughened as mentioned above, it is easy to cause the peeling of the via-hole conductor.
Recently, there is noticed a technique using fine wiring as a circuit pattern in the printed wiring board. The high densification of conductor circuits can be attained by such a fine wiring.
In the fine wired conductor circuits, however, the contact area between the conductor circuit and the solder resist layer becomes considerably small and hence the adhesion property between the conductor circuit and the solder resist layer lowers. Particularly, when the conductor circuits are formed on the surface layer of the printed wiring board at a coarse state, the adhesion property between the conductor circuit and the solder resist layer more lowers.
It is an object of the invention to provide a printed wiring board which improves the adhesion property between the conductor circuit and the interlaminar resin insulating layer and the adhesion property between the conductor circuit and the via-hole conductor to ensure the high connection reliability in the via-hole portion.
It is another object of the invention to provide a printed wiring board which enhances the adhesion property between fine wired conductor circuit and the solder resist layer to strongly adhere the conductor circuit to the solder resist layer even in portions forming solder bumps without peeling and cause no poor continuity in the solder bump forming portions.
DISCLOSURE OF THE INVENTION
The invention lies in a multilayer printed wiring board comprising underlayer conductor circuits, an interlaminar resin insulating layer formed on the underlayer conductor circuits, upperlayer conductor circuits formed on the interlaminar resin insulating layer and a via-hole connecting the underlayer conductor circuit to the upperlayer conductor circuit, in which the underlayer conductor circuit has a roughened surface formed by treating with an etching solution containing copper(II) complex and an organic acid, and the under-layer conductor circuit is connected to the via-hole through the roughened surface.
And also, the invention lies in a multilayer printed wiring board comprising underlayer conductor circuits, an interlaminar resin insulating layer formed on the underlayer conductor circuits, upperlayer conductor circuits formed on the interlaminar resin insulating layer and a via-hole connecting the underlayer conductor circuit to the upperlayer conductor circuit, in which the conductor circuit has a roughened surface, and the roughened surface comprises plural anchor portions, recess portions and ridgelines wherein these anchor portions, recess portions and ridgelines are dispersedly formed and the adjoining anchor portions are connected to each other through the ridgelines and the recess portion is surrounded by the anchor portions and the ridgelines, and the underlayer conductor circuit is connected to the via-hole through the roughened surface.
Further, the invention lies in a multilayer printed wiring board comprising underlayer conductor circuits and an interlaminar resin insulating layer formed on the underlayer conductor circuits, in which the underlayer conductor circuit has a roughened surface formed by treating with an etching solution containing copper(II) complex and an organic acid, and the roughened surface is covered with a metal layer made of at least one metal selected from the group consisting of titanium, aluminum, zinc, iron, indium, thallium, cobalt, nickel, tin, lead, bismuth and noble metal, and the interlaminar resin insulating layer is formed on the roughened surface and a method of producing such a multilayer printed wiring board.
And also, the invention lies in a multilayer printed wiring board comprising underlayer conductor circuits and an interlaminar resin insulating layer formed on the un
En Honchin
Hiramatsu Yasuji
Mikado Yukinobu
Ibiden Co. Ltd.
Lam Cathy
Oliff & Berridg,e PLC
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