JPH05152702A - Printed wiring board - Google Patents

Abstract

PURPOSE:To obtain a printed wiring board capable of high density wiring wherein manufacturing is simple and cost is low. CONSTITUTION:By machining, two or more notches in the direction nearly parallel to the penetration direction of a through hole are formed on a seamless conductor stuck on the wall surface of a through hole part 1 of a printed wiring board by copper plating, solder plating, etc., and said conductor is divided into a conductor 2 and a conductor 3. The wiring patterns on the inner layer and the outer layer of the wiring board are arranged in the manner in which individual wiring patterns 7, 8 are connected with the two respective divided conductors. Thereby two or more individual circuit connections are enabled for one through hole part 1, so that the number of through holes to be arranged can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board having through holes.

[0002]

2. Description of the Related Art In recent years, electronic devices have been sought for high functionality such as high-speed data processing, multi-functional integration, and support for complicated information processing. Although it is becoming stronger, in order to realize this, in electronic parts, especially printed wiring boards, the line width is 0.15 mm.
The following fine patterns, high-density mounting technologies such as small-diameter through holes with a hole diameter of 0.3 mm or less, blind via holes or interstitial via holes, surface mounting compatible, and high-layering technology of 5 to 9 layers or more are rapidly Is making progress.

For high-density mounting within a certain substrate area, if a fine pattern is not sufficient, a multi-layer structure is adopted. At this time, wiring between each layer and mounting of necessary parts are required. Therefore, through holes for component insertion and small diameter through holes are used.

Generally, the through holes are for connecting the layers of the multilayer wiring board and for mounting and soldering the insert-type component, and for soldering the terminals of the insert-type component to the outer surface of the wiring board. Part of the inner wall of the wiring pattern exposed on the wall of the through hole is in contact with this to form the wiring connection between layers. ing.

The through hole has a hole diameter of about 0.9 mm for inserting a terminal (lead) of an insertion type component.

Further, since the small-diameter through hole is used as a connecting wiring between layers of a multilayer wiring board and is not intended to insert a terminal (lead) of a component, the hole diameter can be set to 0.9 mm or less. This corresponds to fine patterning of plates. This small diameter through hole has a hole diameter of 0.3.
Although it has been developed up to about mm, in order to further reduce the diameter, drilling technology with a high aspect ratio, uniform plating technology within a hole with a small diameter, and stabilization of such a small diameter through hole There are many problems to be solved, such as the establishment of manufacturing technology to form the target.

Blind via holes and interstitial via holes, which are one type of these small diameter through holes, are
It is used for connecting the inner layer wiring and the outer layer wiring or a plurality of inner layer wirings without vertically penetrating the outer layer of the wiring board.

These conventional through-holes and small-diameter through-holes only function as one wiring having a branch line per one through-hole when viewed from an electric circuit perspective.
When the circuit is complicated and a large number of wiring board interlayer connections are required, the number of through holes must be increased because the same number of through holes as the required connection circuit must be provided, which complicates the manufacturing process of the printed wiring board. In addition, there is a problem that the manufacturing cost increases accordingly. Also, by providing a large number of such through holes, the wiring area is reduced.
Alternatively, there is a problem that there are many restrictions on the layout of wiring patterns.

Further, even if a small-diameter through hole is used, it must be used frequently, so that the area that can be wired is reduced and the merit of the small-diameter through-hole having a small occupying area at the corner is not utilized. However, if the aspect ratio is too large, drilling becomes difficult, or plating voids and uneven plating thickness occur, which reduces the reliability of through-hole plating. There is also a limit in increasing the wiring density by reducing the occupied area.

[0010]

As described above, in the printed wiring board according to the prior art, a large number of through holes for inter-layer connection must be provided due to the complexity of the circuit and the increase in density, and the occupation of the through holes. Since the area becomes large, the area for arranging the wiring pattern is pressed and it is difficult to increase the wiring density of the wiring board.

Further, if each small-diameter through hole is used, the area occupied by each small-diameter through-hole becomes smaller, but there is a manufacturing limit such as drilling or plating in the small-diameter through-hole itself, and there is a limit in reducing the diameter. If a large number of holes have to be provided, there is a problem that the area where the wiring pattern can be arranged is compressed or that there are many restrictions on the layout of the wiring pattern.

The present invention has been made in view of the above problems, and an object thereof is to reduce the area where a wiring pattern can be arranged by providing a large number of through holes necessary for interlayer connection. Another object of the present invention is to provide a printed wiring board which solves the problem of wiring pattern restriction, enables high-density wiring, is easy to manufacture, and is low in cost.

[0013]

In order to achieve the above-mentioned object, a printed wiring board of the present invention has a through hole, and the through hole has a conductive portion as a part of a connecting wiring of a circuit. In the plate, the conductive portion of the through hole extends in the penetrating direction of the through hole.
It is characterized by having two or more notches and being divided into two or more by the notches.

[0014]

[Function] A conductive portion, which is adhered to the wall surface of the through hole of the printed wiring board by copper plating or the like, a so-called through hole plated portion is extended in a direction substantially parallel to the through direction of the through hole by machining or chemical milling. Make two or more notches. For example, if two notches are provided, the notch divides the conductive part of the wall of the through hole into two surfaces. At this time, the wiring patterns of the inner and outer layers of the wiring board are arranged so that different wiring patterns are connected to each of the two divided conductive parts.

In this way, since two or more wiring patterns are separately connected to each through-hole for each of the divided conductive portions of the through-hole, two or more different interlayers are connected to one through-hole. Connections can be made, and the number of through holes to be drilled can be reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a plan view showing the structure of an embodiment of a printed wiring board according to the present invention, and FIG. 2 is a side sectional view of which part is omitted.

This printed wiring board is a four-layer printed wiring board with a conductor line width of 0.18 mm (3 specifications between pins), small diameter through holes, surface mounting type high density printed wiring that uses a lot of pads for surface mounting ICs. Although it is a plate, a general FR-4 glass epoxy copper clad laminate is used as its substrate material, and its structure is also formed by the subtractive method.

Through hole portion 1 of this printed wiring board
Is provided with a through hole 2, and the conductive portions 3 and 4 are attached to the wall surface of the through hole 2 in a divided manner, and two conductive portions 3 and 4 are provided in the through direction of the through hole 2. The cutout portion 5, the outer layer wiring patterns 6 and 7, and the lands 8 and 9
And inner layer wiring patterns 10 and 11.

The through hole 2 is a hole formed by general NC drilling, and smear is removed after the hole is formed.

So-called through-hole plating such as copper plating and solder plating is applied to the wall surface of the through hole 2 according to the procedure of the subtractive method. The hole diameter of this through hole was set to about 0.9 mm, which is the same as that of a general component insertion type.

The conductive portions 3 and 4 are provided with a notch 5 in parallel with the through-hole penetrating direction by using a fine cutting tool for linear cutting on the one conductor attached by the above-mentioned through-hole plating. 2 streak, notch 5
The conductor on the wall of the hole is completely removed by dividing the conductor in the engraved portion, and the conductor is divided into two separate connecting wirings, the conducting portion 3 and the conducting portion 4.

In the outer layer, outer layer wiring patterns 6 and 7 are connected to the conducting portion 3 and the conducting portion 4, respectively, via lands 8 and 9, respectively. As shown in FIG. 1, the lands 8 and 9 are two individual lands which are also divided in a plane by the cutout portion 5. In the inner layer, the inner layer wiring patterns 10 and 11 are separately connected to the conductive portions 3 and 4 at the end faces exposed on the wall surface of the through hole. As described above, the through hole portion 1 has the conductor 3 and the conductor 4 which are divided into two parts, each of which forms a connection wiring of two separate circuits.

That is, in the circuit of this printed wiring board, the conductive portion 3 is a connection wiring which connects the land 9 and the outer layer wiring pattern 7 to the inner layer wiring pattern 11 to form a part of a circuit of one system. Conducting part 4 is land 8
And a connection wiring that connects the outer layer wiring pattern 6 and the inner layer wiring pattern 10 to form a part of a circuit of one system, and these form separate circuits.

As described above, these two separate circuits are not physically connected to each other through the through hole 2 in the through hole portion 1.
It can be considered that the connection wirings of two circuits which are electrically separated from each other are arranged in this one through hole portion 1.

In FIG. 3, the conductor plated with through holes on the wall surface of the through hole 32 is divided into three conducting portions 36, 37 and 38 by the three notches 35, and one through hole 3 is formed.
FIG. 2 is a plan view showing the configuration of a 4-layer printed wiring board having a through hole portion 31 in which connection wirings of separate circuits of 3 systems are formed in 2;

In this case, the three notch portions 35 divide the conductor attached to the wall surface of the through hole 32 of the through hole portion 31 into three conducting portions 36, 37 and 38, each of which is divided into three portions. It is connected to the wiring pattern of each layer that abuts, forming three separate circuits.

If the number of cutouts is further increased as described above, a larger number of individual circuit connection wirings are formed for each through hole, and a large number of interlayer connection is achieved with a smaller number of through holes. Since the wiring can be secured, the problems related to the conventional technology such as the problem of the reduction of the wiring area due to the provision of a large number of through holes and the problem of the restriction of the routing of the wiring pattern are solved, and the high-density wiring of the printed wiring board can be achieved. Can be realized.

In the case where there is a change in the design of the circuit during the manufacture of the wiring board and it is necessary to connect the circuits which are divided into two or more by the through hole according to the present invention into one. 1 can be easily electrically connected by connecting the gap between the lands 8 and 9 in FIG. 1 with a conductor such as solder, or by inserting a circuit component with a lead terminal and soldering it. It is possible to easily connect to the circuit design change by connecting as a single circuit to. In such a case, the conventional printed wiring board purposely uses a jumper wire for connecting the circuit divided into two or more into one, but the through hole portion of the printed wiring board of the present invention has such a jumper wire. It can be easily connected as described above without using wires.

Further, in this embodiment, the hole diameter of the through hole is set to 0.9 mm as the finished diameter, but if the diameter is further reduced, the wiring density can be further increased.

Further, as a means for dividing the conductor on the wall surface of the through hole, in the present embodiment, a method is used in which conductors that have been pasted seamlessly (one by one) in advance are machined and scraped off using a fine cutting machine. However, in addition to this, for example, a resist is partially adhered to a seamless conductor adhered to the wall surface of the through hole, and the conductor in a portion where the resist is not adhered is selectively removed by etching, By adopting the method of dividing the conductor at the part, or conversely, by using the parteritive additive method, the resist is attached to the part that should be the notch, and only the part where the resist is not attached is selectively It is also possible to form conductive parts by attaching through-hole plating by electroless copper plating or the like.

[0032]

As described above in detail, according to the present invention, a plurality of through-holes required for interlayer connection are provided by arranging a plurality of individual circuit connection wirings for each through-hole. It is possible to provide a printed wiring board that realizes high-density wiring that is easy to manufacture and low in cost, by solving the problems such as the reduction of the area where the wiring pattern can be arranged and the problems of the restriction of the wiring pattern layout. ..

[Brief description of drawings]

FIG. 1 is a plan view showing a through hole portion of a printed wiring board according to the present invention.

FIG. 2 is a side sectional view showing a configuration of a through hole portion of the printed wiring board according to the present invention.

FIG. 3 is a plan view showing a through hole portion having a conductive portion divided into three, of the printed wiring board according to the present invention.

[Explanation of symbols]

 1 ... Through hole part 2 ... Through hole 3, 4 ... Conducting part 5 ... Notch 6, 7 ... Outer layer wiring pattern 8, 9 ... Land 10, 11 ... Inner layer wiring pattern

Claims (1)

[Claims] 1. A printed wiring board having a through hole, wherein the through hole has a conductive portion as a part of a connection wiring of a circuit, wherein the conductive portion of the through hole extends in a penetrating direction of the through hole. A printed wiring board having one or more notches and being divided into two or more by the notches.