JPH11307922A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure the strength of bonding to a lead, by forming a recess of a shape similar to the external form of a through hole opposed to the land provided on a printed wiring board. SOLUTION: Lands 18 made of copper foils on a substrate 12 are provided in parallel in conformity with the leads 14 of IC 10. Then, a through hole 22 round in plan view is provided in each land 18. The distance from the outermost through hole 22a to the corresponding land 18 is shorter than that form the other through holes 22 to the respective lands 18. Only the outermost land 18 is made a round land 24 which has a recess 26 in the shape of a curved surface in plan view only at its section opposed to the through lone 22a. The strength of bonding to this round land 24 is not different at all from the strength of bonding to a usual land 18. Moreover, through the through hole 22a is provided close to the round land 24, the shape of the recess 26 of the round land 24 is curved, so enough distance to the through hole 22a can be kept.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board for an electric circuit used for a liquid crystal display device, a semiconductor device, and other electric products.

[0002]

2. Description of the Related Art As shown in FIG. 4, a plurality of leads 14 for electrically connecting to a printed wiring board (hereinafter, simply referred to as "board") 12 protrude from an IC body 16 of an IC 10. On the other hand, on the upper surface of the substrate 12, a land 18 for electrically connecting to the lead 14 is provided.

When the leads 14 and the lands 18 are connected, they are connected by solder 20, as shown in FIG.

[0004]

The substrate 12 includes a double-layered or multilayered double-sided printed circuit board. In this case, in order to electrically connect the respective layers,
As shown in FIG. 5, a through hole 22 is provided.
In order to reduce the board mounting area for achieving the miniaturization of the device, it is necessary to provide the through hole 22 near the land 18. Usually, the land 18 and the through-hole 22 often have different signals and potentials. If the two are sufficiently close to each other, when mounting the lead 14 on the land 18, the through-hole 22 and the land 18 Are electrically connected to each other, so that a normal circuit function cannot be performed.

Therefore, the land 18 and the through hole 22
It is necessary to arrange them at a predetermined distance so that they are not electrically conducted by the solder 20, and there is a limit in achieving a reduction in the substrate mounting area.

Therefore, conventionally, as shown in FIG. 6, for example, a land 18 in which the through hole 22 is close to a land 18 (hereinafter referred to as a normal land) in which a sufficient distance from the through hole 22 can be ensured, Hall 22
Attempts have been made to increase the mounting density by maintaining the distance between the land 18 and the land 18 as a land (hereinafter referred to as a small land) 18 in which the length of the land is shorter than the length a of the normal land 18 (hereinafter referred to as a small land) 18. Was.

However, in the small land 18, the I
The area connected to the lead 14 of the C10 is
The connection area is naturally smaller than the connection area, and the connection strength is insufficient.

In view of the above problems, the present invention provides a printed wiring board having a land that can secure a sufficient distance from a through hole and a sufficient connection strength with a lead. is there.

[0009]

According to a first aspect of the present invention, there is provided a printed wiring board, wherein a land provided on the printed wiring board has a planar shape which conforms to an outer shape of a through-hole arranged opposite to the land. A concave portion having a bent shape is formed.

[0010] The printed wiring board according to the second aspect is the first aspect.
Wherein the planar shape of the concave portion of the land is
It has a curved shape.

According to a third aspect of the present invention, there is provided a printed wiring board.
Wherein the planar shape of the concave portion of the land is
It is a polygonal shape.

In the printed wiring board having the above structure, since the land has a concave portion that is shaped along the outer shape of the through hole, the electric power can be obtained even when the through hole and the land are provided close to each other. There is no connection.

[0013]

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

FIG. 1 is a partially cutaway plan view showing a case where an IC 10 is mounted on a substrate 12, and FIG.

As shown in FIG. 1, the land 18 is
Plural parallel arrangements are provided in accordance with the zero lead 14. The lands 18 are formed on the substrate 12 by copper foil. A through hole 22 having a plane circular shape is provided inside the land 18.

The through hole 22 and the land 18
Is such that the distance between the outermost through hole 22a and the outermost land 18 is closer than the distance between the other through hole 22 and the land 18.

Therefore, the lands 18 other than the outermost lands 18
As described in the related art, the plane shape is formed by the regular lands 18 having a rectangular shape.

Only the outermost land 18 is
In a planar shape, only a portion facing the through hole 22a has a curved surface shape and a round land 2 having a concave portion 26.
It is 4. This curved surface shape corresponds to the through hole 22a.
(See FIG. 2).

The lead 1 of the IC 10 is mounted on the substrate 12 having the above structure.
4 is connected, as shown in FIG.
The length of the connection between the wire and the normal land 18 is a, while the connection distance of the round land 24 is also a.

As a result, the connection strength of the round land 24 does not differ from the connection strength with the normal land 18 at all. In addition, although the through hole 22a is provided near the round land 24, the shape of the concave portion 26 of the round land 24 has a curved shape along the shape of the through hole 22a. , Through hole 22a
The distance between the lead 14 and the round land 24 can be sufficiently secured even when the lead 14 and the round land 24 are soldered.

FIG. 3 shows a modification of the round land 24.
The shape of the concave portion 26 is a polygonal land 28 forming a polygonal shape.

Even with the polygonal land 28, the connection strength with the lead 14 can be sufficiently ensured, and the distance from the through hole 22a can be ensured.

The through hole 22 in the above embodiment is
Although the through hole as shown in FIG. 5 has been described, the present invention is not limited to this, and may be a through hole having an interspiral buyer hole (IVH) structure.

[0024]

As described above, according to the printed wiring board of the present invention, even if the land is provided close to the through hole, the connection strength with the lead can be sufficiently ensured and the distance from the through hole can be reduced. Since both are effectively secured, there is no possibility that both are electrically connected. for that reason,
The density of wiring on a printed wiring board can be increased, which contributes to downsizing of the device.

[Brief description of the drawings]

FIG. 1 is a plan view of a substrate showing one embodiment of the present invention.

FIG. 2 is an enlarged plan view of a main part in FIG.

FIG. 3 is another embodiment of a land.

FIG. 4 is a plan view showing a state where an IC is mounted on a substrate.

FIG. 5 is a sectional view taken along line AA in FIG.

FIG. 6 is a plan view showing a relationship between a land and a through hole according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 IC 12 Substrate 14 Lead 18 Land 20 Solder 22 Through hole 22a Through hole 24 Round land 26 Depression

Claims (3)

[Claims] 1. A printed wiring board including a plurality of wirings and having, on a main surface thereof, a land for component mounting and a through hole disposed in a plane facing the land, the printed wiring board comprising: A printed wiring board, characterized in that opposing edges have a recessed portion that is shaped along the outer shape of the through hole. 2. The printed wiring board according to claim 1, wherein the planar shape of the concave portion of the land is a curved shape. 3. The printed wiring board according to claim 1, wherein the planar shape of the concave portion of the land is a polygonal shape.