JPH0337879B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to printed wiring boards.

[Prior Art] Conventionally, printed wiring boards have been used in addition to double-sided boards with printed wiring circuits wired on both sides of the board in order to increase the wiring density and downsize the board, as well as multiple printed wiring circuits on one side of the board. Multilayer printed wiring boards have been developed.

In addition, as a multilayer printed wiring board,
There is a multilayer printed wiring board described in Publication No. 42460.

As shown in FIG. 2a, this multilayer printed wiring board has a circuit 13 formed on one side of a substrate 10, terminals 13a and 13b necessary for connection in the circuit 13 are exposed, and the other parts are covered with an insulating coating layer 14. After covering the circuit 13 with a copper coating, a copper coating 16 is deposited on the upper side of the circuit 13 via a base circuit 15, and a connection circuit 17 is formed via the copper coating 16.

Therefore, in this type of multilayer printed wiring board, a multilayer printed wiring board 20 in which a land 19 portion is present in the printed wiring circuit 18 of the second layer diagram, as shown in FIG. 2b, is also manufactured, and in this case, There is no portion such as a connecting land between the connecting circuit 17 and the first layer circuit 13 between the land 19 and the substrate 10, and only the insulating coating layer 14 is interposed therebetween.

In addition, 21 in the figure is the printed wiring circuit 1 of the second layer.
7 and 18 show the insulating coating layer deposited on the upper side.

[Problems to be Solved by the Invention] However, due to the necessity of the circuit design, the lands 19 in the second layer printed wiring circuit 18 are wired on the substrate 10 via the insulating layer 14 and are not connected to other printed circuits. Unlike the wiring circuit 17, it is not wired on the substrate 10 via the first layer printed wiring circuit 13.

Therefore, the insulating layer 14 is usually formed by coating with an insulating resin, and the lands 19 are connected to the first layer printed wiring circuit 13.
The adhesion strength is lower than that of the printed wiring circuit 18 that is wired on the board 10 via the land, and when punching a through hole in the land, the intervening layer of the insulating layer 14 lowers the processing accuracy. There was a problem with that.

Therefore, the present invention was developed in view of these drawbacks, and it is an object of the present invention to provide a multilayer printed wiring board that can improve the adhesion strength of lands and the processing accuracy of through holes in the second layer printed wiring circuit. The purpose is to

[Means for Solving the Problems] The present invention provides a multilayer printed wiring board in which a multilayer printed wiring circuit is provided on at least one side of a board, in which a printed wiring circuit in a second layer of the multilayer printed wiring circuit is provided. This is constructed by providing a reinforcing land.

[Function] The present invention improves adhesion strength and through-hole processing accuracy at the same time as the printed wiring circuit wired on the first layer printed wiring circuit by the radon reinforcement land in the second layer printed wiring circuit. Uniformity can be obtained.

[Example] An example of the printed wiring board of the present invention will be described below with reference to the drawings.

1 is the board of printed wiring board 2, 3 is this board 1
The first layer printed wiring circuit 4 is wired on one side of the first layer printed wiring circuit 3, and the second layer printed wiring circuit 4 is wired on the first layer printed wiring circuit 3. An insulating layer 5 is interposed between the parts.

Therefore, 6 is the printed wiring circuit 4 of the second layer.
A reinforcing land for the land 7 is formed on the substrate 1, and the land 7 is wired on the substrate 1 via the reinforcing land 6.

Furthermore, although this reinforcing land 6 is electrically completely independent from the first layer printed wiring circuit 3 in terms of circuit design, it is formed at the same time as the wiring of the first layer printed wiring circuit 3. The first one on one side of the board 1
In order to form the printed wiring circuit 3 of the second layer, the copper foil is formed in advance using stretched copper foil.

Furthermore, regarding the diameter of the reinforcing land 6, although the case where it is formed larger than the diameter of the land 7 is shown, it may be the same diameter or a diameter larger than the through hole opened in the land 7 and smaller than the diameter of the land 7. It is also possible to form

FIG. 1b shows an embodiment in which a through hole 8 is opened in the land 7 in FIG. 1a.

[Effects of the Invention] According to the present invention, it is possible to directly wire the lands in the printed wiring circuit of the second layer or higher to the board by means of reinforcing lands without using an insulating layer, thereby improving the adhesion strength of the land portions. In addition to improving the overall strength of the printed wiring circuit.

In addition, by removing the interlayer of the insulating layer between the land and the board, and using the intervening layer of the reinforcing land, it is possible to process through holes by punching without defects such as variations in processing accuracy due to the insulating layer. Machining accuracy can be improved.

[Brief explanation of the drawing]

1A and 1B are enlarged partial sectional views showing an embodiment of the multilayer printed wiring board of the present invention, and FIGS. 2A and 2B are enlarged partial sectional views of a conventional multilayer printed wiring board. 1... Board, 2... Multilayer printed wiring board, 3...
...First layer printed wiring circuit, 4... Second layer printed wiring circuit, 5... Insulating layer, 6... Reinforcement land, 7... Land, 8... Through hole.

Claims (1)

[Scope of Claims] 1. In a multilayer printed wiring board in which a multilayer printed wiring circuit is provided on at least one side of a board, the adhesion strength of a land in a second layer of the multilayer printed wiring circuit is reinforced. 1. A multilayer printed wiring board characterized in that a reinforcing land is provided in the same layer as a first layer printed wiring circuit. 2. The multilayer printed wiring board according to claim 1, wherein the reinforcing land has a diameter larger than that of a through hole provided in a land in the printed wiring circuit. 3. The multilayer printed wiring board according to claim 1, wherein the reinforcing land has a diameter equal to or larger than the diameter of the land in the printed wiring circuit.