JPH0542157B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a multilayer printed wiring board and a method for manufacturing the same, and particularly to a multilayer printed wiring board in which a conductor layer has divided through holes in some parts for high-density packaging. Regarding wiring boards.

[Conventional technology]

In a conventional multilayer printed wiring board, not only holes for inserting components but also via holes (hereinafter referred to as via holes) are made by drilling through holes and attaching conductors to the hole walls by means such as electroless plating. Formed by providing layers.

In addition, in another type of conventional multilayer printed wiring board (hereinafter abbreviated as multilayer board), as the number of layers increases, a design in which embedded via holes are provided in some of the inner layers is also being adopted.

In recent years, attempts have been made to increase the packaging density of electronic devices due to performance and economical needs. For this reason, not only are electronic devices such as ICs and LSIs becoming more highly integrated and faster, but the multilayer boards on which these devices are mounted are also becoming more dense.

Two attempts have been made to increase the density of multilayer boards. In other words, the first attempt was to increase the number of conductor layers, and the second was an attempt to increase the number of conductor layers.
The attempt is to pass many wires between the grid patterns. However, the first attempt results in an increase in via holes connecting the interlayer conductor layers. Particularly when the via hole 5 is provided as a through hole in the multilayer board as shown in FIG. 2, the number of wiring lines in the above-mentioned second attempt is significantly limited. This has been dealt with by reducing the diameter of the via hole 5, but as the number of layers increases, the plate thickness also increases, and the ratio of plate thickness/hole diameter (aspect ratio) increases, significantly reducing the productivity of multilayer plates. It's hindering. In addition, in fields that require ultra-high density, so-called buried via holes, which are multi-layered with 10 or more layers and have via holes in the inner layers, have been adopted, but they are not satisfactory in terms of performance. From an economic point of view, it did not satisfy all needs.

Furthermore, there is a need to solve the above-mentioned problems in multilayer boards, especially in multilayer boards with 5 to 10 layers, whose demand is expected to increase in office automation equipment (OA equipment) and the like.

As an attempt to achieve this goal, “Making”
100000 Circuits Fastest Where Most
Making 100000
Circuits fit where at most 6000 fit before;
Electronic, August 2, 1979), Figure 3C
The blind via holes shown in Fig. 1, i.e., non-through holes, improve the wiring capacity.

[Problem that the invention seeks to solve]

However, from a manufacturing perspective, “Lasers in Erectoronics”
Circuit Manufacturing, July, 1981)” or “Copper Plating Advanced Multilayer Board (Copper Plating Advanced Multilayer Board)”
Advanced Multilayer Boards; IPC, 1976
As introduced in ``Fall Meeting'', the multilayer plate 1 as shown in Figure 3A is removed by laser or drilling.
However, as shown in FIG. 3C, blind via holes 5-1 and 5-2 are formed on each side, which is inefficient.

Furthermore, in laser drilling, as shown in FIG. 3B, the outermost copper foil of the multilayer board 1 at the position P-2 where the via hole is to be drilled is removed by etching, and then the via hole is drilled. There is a drawback that a detailed process is required.

In addition, after drilling a via hole, a conductive layer is formed on the entire surface including the inner wall by electroless plating.
If the distance between the outermost insulating layers 1a-1 and 1a-2 in FIG. 3D is thick, it is difficult to form a uniform conductor layer, which is unfavorable in terms of reliability.

An object of the present invention is to provide a multilayer printed wiring board and a method for manufacturing the same that eliminates the structural defects of conventional multilayer boards.

[Means for solving problems]

According to the present invention, a pair of insulating plates containing a catalyst and capable of being attached by plating, each having a conductive circuit pattern on both the front and back sides, is arranged on the outermost side, a prepreg layer containing a catalyst is arranged inside the insulating plate, and A catalyst-free insulating plate with holes cut out in concentric circles larger than the diameter of the through-holes is placed in advance at the positions of the through-holes for front-to-back conduction of the multilayer printed wiring board, and heated and pressurized to eliminate the catalyst. forming a multilayered substrate by filling the hollowed-out hole portion of the insulating plate with the catalyst-containing resin that has flowed out from the catalyst-containing prepreg layer; and forming the through-holes for front and back conduction and the inner layer conductor pattern on both the front and back surfaces of the multilayered substrate. A process of providing a certain clearance at the position of the through hole for connection and applying an insulating resin layer without a catalyst to the desired part, and drilling the through hole for front and back conduction and the through hole for connecting the inner layer conductor pattern. and a step of electroless plating the multilayered substrate to form a conductive layer on the portions exposed from the catalyst-free insulating resin layer on both the front and back surfaces and the catalyst-containing insulating layer on the inner wall of the through hole. A method for manufacturing a multilayer printed wiring board is obtained.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1E shows an embodiment of the multilayer board of the present invention, in which a catalyst-containing laminate 1a-1 containing metal palladium, etc., which acts as a catalyst for electroless copper plating, is uniformly dispersed.
1, 1a-2 and prepreg layer 1b with catalyst
is vertically separated by a catalyst-free insulating plate 3, and has conductor layers 7-1 and 7-2 separated in a ring shape within a via hole 5 serving as a through hole.

Next, an embodiment of the method for manufacturing a multilayer board according to the present invention will be described in detail with reference to FIGS. 1A to 1E.

Figure 1A shows a laminated structure, and a laminated plate 1a with a catalyst.
Desired circuit patterns 2-1 to 2- by known printing and etching methods on both sides of -1 and 1a-2.
4 is placed on the outermost side, prepreg layers 1b-1 and 1b-2 with catalyst are placed on the inside thereof, and holes for inserting parts of the multilayer board are to be drilled inside the multilayer board. P-1 is combined with catalyst-free insulating plate 3, which has concentrically hollowed holes larger than the diameter of the holes for inserting parts, and is integrally formed by heating and pressurizing to obtain the multilayer plate shown in Figure 1B. .

Next, in order to prevent unnecessary conductor layers from being formed on the surface of the multilayer board 1, a permanent mask layer 4 having insulating properties and chemical resistance is formed on desired portions as shown in FIG. 1C.

Next, as shown in FIG. 1D, a via hole 6 for inserting components and a via hole 5 for connecting the inner layer are drilled.

Next, when electroless copper plating is applied to the entire surface, a copper-plated conductor layer 7 is formed on the exposed conductor layer and on the inner walls of the via holes 5 and 6, as shown in FIG. 1E. In the hole 5, a copper-plated conductor layer 7 is formed by a catalyst-free insulating plate 3, a conductor layer 7-1 connecting layers 1-2 and a conductor layer 7-2 connecting layers 3-4.
This results in a multilayer board spaced apart.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to drill holes without using special means such as a laser, or non-mass-produced conventional means of drilling non-through holes one by one, thereby significantly improving productivity. This has the effect of improving the reliability of inner layer connections and providing high-density multilayer printed wiring with markedly improved wiring accommodation.

[Brief explanation of the drawing]

Figures 1A, B, C, D, and E are sectional views showing an embodiment of the present invention in the order of steps; Figure 2 is a sectional view of a conventional example; and Figure 3 A, B, C, and D are sectional views of a conventional example. FIG. 7 is a sectional view showing another example in order of steps. 1...Multilayer printed wiring board, 1a-1...Laminated board with catalyst forming 1-2 layers, 1a-2...3-4
Laminated plate with catalyst forming layers, 1b, 1b-1,
1b-2...Prepreg layer with catalyst, 2-1 to 2
-4... 1-4 layer conductor pattern, 3... Insulating plate without catalyst, 4... Permanent mask layer, 5, 6... Via hole, 5-1, 5-2... 1-2 layer, 5-
Blind via holes connecting 6 layers,
7, 7-1, 7-2...Copper-plated conductor layer by electroless copper plating, P-1...Position where a through hole for inserting components is drilled, P-2...Via hole Location to be drilled.

Claims (1)

[Scope of Claims] 1. A set of catalyst-containing insulating plates capable of being attached with plating, each having a conductor circuit pattern on both the front and back surfaces, is placed on the outermost side, a catalyst-containing prepreg layer is placed on the inside thereof, and A catalyst-free insulating plate is placed inside the multilayer printed wiring board, and the catalyst-free insulating plate has a concentric hole cut out in a concentric circle larger than the diameter of the through-hole at the position of the through-hole for conduction between the front and back sides of the multilayer printed wiring board. forming a multilayered substrate by filling the hollowed-out hole of the non-insulating plate with the catalyst-containing resin that has flowed out from the catalyst-containing prepreg layer; and forming the through-holes for front and back conduction and the inner conductor on both the front and back surfaces of the multilayered substrate. A step of providing a certain amount of clearance at the position of the through hole for pattern connection and applying an insulating resin layer without a catalyst to the desired part; and a step of electroless plating the multilayered substrate to form a conductor layer on the portions exposed from the catalyst-free insulating resin layer on both the front and back surfaces and the catalyst-containing insulating layer on the inner wall of the through hole. A method for manufacturing a multilayer printed wiring board, characterized by: