JPS5927079Y2 - wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wiring board, and more particularly to a high-density wiring board formed by wiring and fixing insulated conductors in a desired circuit pattern on an insulating substrate.

In recent years, a copper foil conductor pattern has been formed on an insulating substrate as necessary, and a desired circuit pattern of insulated conductor wires has been wired and fixed via an adhesive insulator layer, and then through holes have been formed at desired positions. , a wiring board in which electrical connections are made by forming a metal conductor layer on the inner surface of the through hole is being considered.

Generally, this type of wiring board has the following characteristics.

Since insulated conductors are used as signal circuits, the signal circuits can intersect on the same plane, and patterns for two sides of a normal printed wiring board can be accommodated on one side, making it possible to connect the front and back sides. Through-holes are no longer needed.

Furthermore, since through-holes for connection are not required, the number of channels that can be used increases when determining wiring routes, and wiring design becomes easier.

In addition, original drawings and photographs of circuit patterns are not required.
For example, turnaround time can be shortened.

An example of this type of conventional wiring board will be described below with reference to FIGS. 1 and 2.

Normally, this type of wiring board is manufactured using glass, as shown in Figure 1a.
A patterned copper foil layer 2 is formed on one or both sides of an insulating substrate 1 made of epoxy or the like so that it can be used, for example, as a power supply layer or a ground layer as required, and then as shown in Figure 1, the insulating substrate 1 and the copper foil layer 2, an insulating layer 3 having adhesive properties (hereinafter referred to as an adhesive insulating layer) 3 is laminated on both sides by laminating or other method to press and bond, as shown in FIG. 1C. A desired circuit pattern of the insulated conductor 4 as a signal circuit is wired and fixed to the adhesive insulating layer 3 by, for example, numerically controlled automatic wiring, and further, in order to protect the wired and fixed circuit pattern of the insulated covered conductor, for example, An insulating cover layer 5 is formed by laminating and bonding glass and epoxy prepreg (see FIG. 1d).

When forming a metal conductor layer in a through hole by electroless plating to create a through hole in a later process, the materials described, i.e.,
The insulating substrate 1, the adhesive insulating layer 3, and the cover layer 5 are usually made of materials that have catalytic properties for electroless plating, and as shown in FIG. 1d, the outer surface of the cover layer 5 is coated with electroless plating. On the other hand, a non-catalytic plating mask (hereinafter referred to as a plating mask) 6 is formed on the entire surface, and as shown in FIG. The cross sections of the insulated conductor 4 and the copper foil layer 2 are exposed on the inner surface of the through hole 7 by drilling, and then the inner surface plating film of the through hole 7 is formed by immersing it in an electroless plating solution. Then, a metal conductor layer 8 is formed to form a through hole, and the first
As shown in FIG. f, the plating mask 6 was removed to form a wiring board as shown in the perspective view of FIG. 2, thereby achieving electrical connection.

On the other hand, with the recent progress in high-density packaging, in order to further increase the wiring capacity of this type of wiring board, the wiring route of insulated conductor wires allowed on the wiring board has been subdivided, and the number of wires has increased. Density wiring boards are being used.

FIG. 3 is a wiring route diagram showing an example of a conventional high-density wiring board of this type, in which an insulated conductor is placed between through holes 7 and 7' provided at the intersection of the main grid 9 of 2.54 mm pitch wiring. Two pieces of 4 are provided.

Automatic design using a computer is usually applied to search for the wiring path design of this conventional high-density wiring board, and in FIG.
For example, among the sub-lattice 10 of 0.508 mm which is divided into five parts, the sub-lattice 10' sandwiched by the outer periphery of the through hole 7 is allowed as a wiring channel.

In this way, the number of wiring channels is subdivided, and the number of insulated conductors is
It is expected that the wiring capacity can be further increased by increasing the wiring density.

However, this type of conventional high-density wiring board has the following drawbacks.

That is, since the wiring channel is subdivided, the gap between the insulated conductor 4 and the through holes 7, 7' becomes smaller, as shown in FIG. 3, and as a result, the insulation resistance between the insulated conductor 4 and the through holes 7 is It was confirmed that the battery deteriorates, and in the worst case, it causes a short circuit.

As a result of analyzing this phenomenon, it was found that in wiring boards where the insulation resistance between the insulated conductor 4 and the through hole 7 has deteriorated, there is a misalignment during the formation of the through hole 7 during the manufacturing process mentioned above, and the insulated conductor 4
As a result of accumulated errors due to misalignment during wiring fixation, the gap between the insulated conductor 4 and the through hole 7 becomes extremely small, and the chemical process such as the plating pretreatment and plating process after the formation of the through hole 7 becomes extremely small. It was confirmed that during the treatment process, chemicals penetrated through the adhesive insulating layer 3 and the cover layer 5, and as a result, the insulation properties deteriorated.

As a means to eliminate the drawbacks of this type of conventional wiring board, methods such as reducing the diameter of the insulated conductor wires, narrowing the distance between the insulated conductor wires, that is, reducing the pitch dimension of the sub-lattice 10' have been considered. However, the former is currently 0°16mm or 0.1mm within the range where reliability is guaranteed.
4mm diameter insulated conductor is the limit.

In the latter method, there is a limit to the minimum pitch between the insulated conductor wires, and neither method is perfect.

An object of the present invention is to provide a new high-density wiring board that eliminates the drawbacks of conventional wiring boards of this type.

According to the present invention, in a wiring board formed by wiring and fixing insulated conductive wires on a board, the insulated conductive wires provided on the wiring board are arranged to cross each other in a gap between adjacent through holes. A wiring board is obtained.

The present invention will be explained below with reference to FIG.

FIG. 4 is a plan view showing an embodiment of the present invention, in which insulated conductors 4 and 4' arranged on a substrate are arranged in a gap between adjacent through holes 7 and 7'. Cross-arranged.

In the area where the through holes 7, 7' are not provided on the substrate, the insulated conductive wires 4 are arranged parallel to each other on the sub-grid 10'.
, 4' pass through the area of the through holes 7L7, 7' arranged adjacent to each other, they are first bent to each other at the bending point 11, and the main lattice 9 is perpendicular to the running direction of the insulated conductors 4, 4'. It is crossed at the top position 12 and then bent again at the pitch position 13 (of the main grating 9).

If the through-holes 7, 7' still exist, the insulated conductive wires 4, 4' are similarly arranged to cross each other.

Bend lines 11 and 13 of insulated conductors 4 and 4', intersection 1
It is necessary to select the optimum value for the position of 2 according to the diameters of the main grid 9, the sub-grid 9, the sub-grid 10', the through holes 7, 7', and the diameters of the insulated conductive wires 4, 4'.

This optimum value is based on the insulated conductors 4, 4' and the through holes 7, 7'.
Of course, it is desirable to have as large a gap as possible between the outer periphery and the outer periphery, but experimental results have confirmed that this gap should be set to a minimum value of Q, about 45 mm.

For example, as an example, the diameter of the through holes 7, 7' is l, 1 m.
m, main grid pitch 2.54 mm (100 mil),
Among the pitches of the sub-grid, the through holes 7, 7' and the insulated conductor 4
, 4' is 1.016 mm (40 mil), and the distance between the insulated conductors 4 and 4' is 0.508 mm (
20 mil) The diameter of the insulated conductors 4 and 4' is 0.14 mm.
Then, the bending point 11 is made to coincide with the side of the sub-lattice 10' near the through hole 7.degree. 7', and the intersection point 12 is provided on the main grating 9 divided by the pitch.

Further, the bending points 13 are generated at the center pitch of the main grating 9.

In such a case, in the conventional wiring board shown in FIG. 3, the minimum distance between the insulated conductors 4, 4' and the through hole 7.7 is approximately Q
, 4 mm, and in FIG. 4 of the embodiment according to the invention, the minimum spacing can be 0.45 mm or more.

As described above, the present invention provides the following advantages when designing wiring routes for insulated conductors:
without the need for increased computer memory capacity.
Furthermore, it is possible to realize high-density wiring with improved insulation properties using extremely simple means, and the effect is extremely large.

Note that the dimensions of the through holes 7, 7', the diameters of the insulated conductors 4, 4', the main grid 9, the sub-grids 10, 10', etc. shown in FIG. 4 are limited to the dimensions shown in the examples. Of course, it is nothing.

[Brief explanation of the drawing]

FIGS. 1 a-f are cross-sectional views showing the manufacturing process of a conventional wiring board;
2 is an enlarged perspective view of FIG. 1f, FIG. 3 is a plan view showing the wiring path of a conventional wiring board, and FIG. 4 is a plan view showing the wiring path of the wiring board according to the present invention. 1: Substrate, 2: Copper foil layer, 3: Adhesive insulating layer, 4.4'
: Insulated conductor, 5: Single layer cover, 6: Plating mask, 7
゜7': Through hole, 8: Metal conductor layer, 9: Main lattice, 10.
10': Sub-lattice, 11.13: Bend point (of the insulated conducting wire), 12: Intersection (of the insulated conducting wire).

Claims (1)

[Scope of utility model registration request] In a wiring board formed by wiring insulated conductor wires on a board,
A wiring board characterized by having a region where a plurality of the insulated conductive wires cross each other and pass through a gap between adjacent through holes.