This invention relates to a laminated product in a structure including a glass-cloth contained resin layer and a method for manufacturing the same. More specifically, this invention relates to a product in a multiple-layer structure including a layer of glass-cloth contained resin known as “prepreg” as a reinforcement layer, e.g. a product such as a multiple-layer substrate or package, and a method for manufacturing the same.
As a method for manufacturing a multiple-layer structure such as a multiple-layer wiring board, a “build-up” technique is known. In the build-up technique, on a core substrate with a wiring layer formed as a first layer, insulating layers and wiring layers are alternately formed to form a wiring board in a multiple-layer structure. For conduction between different wiring layers, a via hole passing through the insulating layers between these wiring layers is made.
In order to satisfy the demand of downsizing or weight-reduction in recent years for electronic components, low-profiling of the multiple-layer wiring board is required. In order to realize this, in recent years, the product in a multiple-layer structure has been manufactured by inserting a prepreg layer giving a high reinforcement effect. This is attributable to the fact that although the prepreg is known as a material inferior in laser processing, owing to improvements of a laser processing technique, also in the multiple-layer structure including a prepreg layer for reinforcement, the via hole for conduction between the layers has become capable of being formed.
The technique for making the via hole in fabrication of the wiring board in the multiple-layer structure including the prepreg is disclosed in Patent Reference 1. In accordance with this technique, as shown in
Patent Reference 1: JP-A-2004-356232
In the method for manufacturing the multiple-layer wiring board disclosed in Patent Reference 1, the laser processing must be done twice in the formation of the via hole 113 for making the larger-diameter hole 107 and small-diameter hole 111, thereby complicating the processing steps. In addition, in order to make the small-diameter hole inside the large-diameter hole, higher laser processing accuracy is required than the case of making a single hole. Further, subjecting the small-diameter hole 111 which is preferably 120 to 50 μm to the conducting processing cannot be carried out so easily.
In view of the above circumstance, an object of this invention is to provide a laminated product including a glass-cloth contained resin layer having a multiple-layer structure capable of making a via hole by a simple step, and a method for manufacturing the same.
According to the present invention, there is provided a laminated product including: a wiring layer and an insulating layer being alternately laminated, and different wiring layers being electrically connected to each other by a via hole passing through the insulating layer, wherein at least one of the insulating layers is a laminated body including: an insulating resin layer on a lower wiring layer and a glass-cloth contained resin layer thereon, and in the laminated body, the via hole continuously passes through from the glass-cloth contained resin layer to the insulating resin layer.
Further, the laminated product including a glass-cloth contained resin layer according to the present invention is manufactured by a method including the steps of: alternately laminating at least one set of a wiring layer and an insulating layer on a lower board with a wiring layer, and electrically connecting different wiring layers to each other by a via hole passing through the insulating layers, making at least one of the insulating layer be a laminated body including: an insulating resin layer and a glass-cloth contained resin layer successively formed on a lower wiring layer, and laser processing the laminated body so that a hole for making the via hole is continuously made from the glass-cloth contained resin layer to the insulating resin layer.
In accordance with this invention, there is provided a via hole made using a continuous through-hole made by collectively laser-processing a glass-cloth contained resin layer and an insulating resin layer therebelow which constitute a composite insulating layer lying between an upper and a lower wiring layer. In the case of a conventional method for making the via hole which requires that different resin layers are formed and laser processing is done for the resin layers, respectively, high laser processing accuracy is required as compared with the collective laser processing for two layers. On the other hand, the laminated product according to this invention capable of collectively laser-processing the glass-cloth contained resin layer and the insulating resin layer therebelow can be given as a multiple-layer product by a simple step and at low cost. Further, in accordance with this invention, conduction processing for the thorough-hole can be done more simply as compared with the conduction processing for the hole with a small diameter which is finally made by executing the laser processing twice according to the conventional art.
The lower wiring board 3 equipped with the lower wiring layer 5 may be a core board which is used to manufacture a multiple-layer board having a build-up layer formed thereon. Otherwise, it may be such a core board having at least one set of insulating layer and wiring layer built-up thereon.
The insulating resin layer 7 which constitutes the insulating layer 11 can be made of an insulating resin which is generally used to form an interlayer insulating layer in the multiple-layer wring board. This insulating resin may contain e.g. a filler of glass particles. The glass-cloth contained resin layer 9 located on the insulating resin layer 7 is made by impregnating the glass-cloth with the insulating resin, and is made of the material called “pregreg”. Both materials can be selected from the materials which are generally used in manufacture of the multiple-layer wiring board.
The glass-cloth contained resin material used to form the glass-cloth contained resin layer 9 is commercially available as the product having a predetermined thickness. The product having a thickness enough to obtain a necessary reinforcement effect can be selectively adopted. For example, the material having the thickness of about 40 μm or 60 μm can be employed. The insulating resin layer 7 underlying the glass-cloth resin layer 9 is formed with such a thickness that the laminated body of itself and the glass-cloth contained resin layer 9 has the thickness necessary to assure the insulation between the upper and lower wiring layers. The thickness is generally about 40 to 100 μm.
The via hole 17 which continuously passes through the upper glass-cloth contained resin layer 9 and the lower insulating resin layer 7 can be formed by a CO2 laser device as in a common via hole material. The diameter of the via hole 17 is not particularly limited, but generally 100 to 300 μm, preferably about 150 to 200 μm.
Now referring to
As shown in
Subsequently, using the laser device LC-2G manufactured by e.g. Hitachi Via Mechanics, Ltd, the glass-cloth contained resin layer 9 and the insulating resin layer 7 underlying it are successively processed to make a hole 15 having a diameter of 150 μm which passes through the glass-cloth contained resin layer 9 and the insulating resin layer 7 so as to expose a part of the lower wiring layer 5, as shown in
Next, as shown in
Hitherto, the laminated product according to this invention has been explained with reference to the multiple-layer board. However, without being limited to it, the laminated product according to this invention can also be applied to various products in the multiple-layer structure including the glass-cloth contained resin layer as a reinforcement layer, e.g. a package product. Therefore, it should be understood that the laminated product according to this invention includes these various products.
Number | Date | Country | Kind |
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2005-244219 | Aug 2005 | JP | national |