JP2510576Y2 - Printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a printed wiring board.

[Conventional technology]

A conventional solder land for mounting an electronic component on a printed wiring board and brazing it will be described with reference to FIGS.

That is, the printed wiring board is a board 1 made of an insulating material.
Formed by forming a printed circuit (the portion of metal layer 2 in the figure) formed by etching a metal layer formed by pasting copper plating or copper foil on the surface of and then providing a masking layer 4 on the surface. are doing. As is well known, the masking layer 4 is formed for the purpose of preventing the solder from adhering during outer brazing such as electrical insulation and moisture proof.

Then, in order to attach each component forming the electronic circuit to the substrate 1, through holes 8 and 9 are provided penetrating the substrate 1 and the metal layer 2, and a solder land around which the solder is fused.
10 and 12 are provided. The solder lands 10 and 12 expose the metal layer 2, and the large-diameter solder land 10 is a solder land for retrofitting, and the small-diameter solder land.
12 is a solder land for simultaneous brazing of each component (not shown) mounted on the printed circuit.

By the way, as is well known, when brazing a large number of electronic components, the solder land side is brought into contact with the molten solder to perform brazing all at once, thereby improving the brazing work efficiency and deteriorating the electronic components due to heat. I try to prevent it. During this simultaneous brazing, the molten solder adheres to the solder lands 10 as well, but at that time, the film closes the through holes 9 due to surface tension, or the solder bulges into the holes to cause solder fogging that reduces the hole diameter. (Hereinafter, these problems are collectively referred to as solder fogging). Masking with a tape in order to avoid this solder fogging significantly deteriorates the workability of assembling, and if the through hole 9 is made large, there is a problem that the workability of the brazing due to the subsequent work is deteriorated, which is not practical.

Therefore, conventionally, a slit (notch) 14 is provided by separating a part of the solder land 10.
That is, when the molten solder is adhered to the solder land 10, the solder does not adhere to the slit 14, and the solder is cut off from this portion, so that the solder fogging can be prevented.

As shown in FIG. 5, the notches 14 are all directed in the same direction, but they are made to flow in a certain direction in order to remove the oxide film formed on the liquid surface of the molten solder. In order to prevent the solder fog, it is preferable to arrange the pin hole 9 on the upstream side of the molten solder and the slit 14 on the downstream side.

[Problems to be solved by the device]

In addition, JP-A-54-113050, JP-A-1-97597, and JP-A-60-141169 propose a device for preventing clogging of a solder land.

If the width of the slits provided in the conventional solder lands shown in FIGS. 5 and 6 is widened to improve the solder fogging prevention effect, the brazing area becomes smaller, which makes brazing uncertain. There is a problem of reducing workability. Further, in the case where a part of the solder land is masked in a strip shape, the metal layer is exposed around the through hole, which causes solder fog and cannot prevent solder fog.

Also, in the inventions disclosed in Japanese Utility Model Publication No. 54-113050 and Japanese Utility Model Publication No. 1-97597, the notch provided around the through hole of the solder land is narrower than the diameter of the through hole. Moreover, since the metal layer is widely exposed in the through hole, the solder is likely to adhere to it, and the solder fogging cannot be sufficiently prevented.

Further, in the device disclosed in Japanese Utility Model Publication No. 60-141169, an extension portion is formed on the outer peripheral portion of the solder land, and a notch portion continuous with the through hole and having the same width as the through hole is formed. Although it is formed, since the masking portion is limited to the width corresponding to the diameter of the through hole, soldering is also poor in this structure. This phenomenon remarkably appears especially when the through hole has a small diameter.

An object of the present invention is to provide a printed wiring board that can reliably prevent soldering of solder lands for post-mounting on the printed wiring board and prevent a decrease in solder strength after the post-soldering.

[Means for solving the problem]

The printed wiring board of the present invention for achieving the above-mentioned purpose is for brazing a connector for connecting a printed circuit formed by etching the metal layer 2 on the substrate 1 and a circuit outside the printed circuit. A solder land 10 formed by etching the metal layer 2 is provided, and the solder land 10 has a through hole 9 that penetrates the substrate 1 and inserts the connector. A lateral side a which is enlarged to a vertical side b extending in the peripheral direction of the solder land 10 and a lateral side c which is substantially parallel to the lateral side a, and which is formed so as to include a half circumference portion of the through hole 9. A notch portion 18 is provided, and the notch portion 18 and the outer peripheral edge of the solder land 10 are connected to each other to form a masking layer having a band-shaped portion 20 narrower than the width of the through hole 9.

For the substrate, the metal layer, and the masking layer when implementing the present invention, the materials conventionally used can be used as they are.

The connector connecting the printed circuit and the circuit outside the board is
Refers to conductors for circuit connection such as lead rods and lead wires.

The position where the notch and the band are provided on the solder land is not particularly limited. As a preferable position, there are a plurality of solder lands, and when the printed wiring board is brought into contact with the flow of the molten solder to be brazed, the strip-shaped portions are arranged so that the strip-shaped portions are oriented in the direction perpendicular to the flow. Form a notch.

The notch formed as described above allows the exposed portion of the metal layer to be only a semicircle at the edge portion of the through hole, and is formed continuously with the through hole and wider than the diameter of the through hole. Since it is possible to provide a wide area of the masking layer covering the cutout portion, it is possible to reliably prevent soldering of the through hole. This is especially effective when the through hole has a small diameter.

Also, since the width of the strip-shaped masking layer is narrower than that of the through hole, the circle of the solder land to which solder is attached at the time of post-installation is different from the conventional technology in which the masking layer that cannot be brazed is wider than the notch. Since the area of the metal layer in the circumferential direction can be wide, a large solder strength can be realized. Further, in this solder land, since the metal layer is continuous in the circumferential direction except for the through hole and the notch portion, a uniform temperature distribution in the solder land portion, which is an advantageous condition during brazing, can be obtained. The solder can be reliably attached.

〔Example〕

Hereinafter, the printed wiring board 16 of the present invention will be specifically described by way of examples with reference to the drawings.

As shown in the figure, a printed circuit formed by etching a metal layer 2 made of copper foil on a board 1 is provided with a solder land 10 for post-mounting for connecting external parts (not shown), and a board 1 provided with an illustration. Solder lands 12 for brazing the parts that are not provided are provided.

FIG. 3 is a diagram showing a printed wiring board before the masking process, and the solder lands 10 for retrofitting are provided on the metal layer 2 forming a part of the printed circuit,
A notch 18 is formed along the edge of the through hole 9 by removing a part of the metal layer 2.

As shown in FIG. 4, the shape of the cutout portion 18 of the solder land 10 includes a lateral side a which is diametrically enlarged from the peripheral edge of the through hole 9 and a vertical side b which extends toward the peripheral edge of the solder land 10. , A lateral side c substantially parallel to the lateral side a, and forms a wide notch continuous with the through hole 9.

The masking layer 4 is formed on the entire surface excluding the solder lands 10 and 12, like the conventional printed wiring board. Then, in the solder land 10, as shown in FIG. 3, the notch 18 is exposed and the surface 22 of the substrate is exposed. When the masking layer 4 is formed, the cutout portion 18
Also, a masking layer is formed on the strip portion 20 extending from the notch portion 18 across the solder land 10. This strip 20
Connects the notch 18 and the outer peripheral edge of the solder land 10,
It is formed to be narrower than the width of the through hole 9. When molten solder (not shown) is attached to the solder lands 10, 12 side of the printed wiring board 16 described above and pulled up, solder is applied to the masking layer formed in the cutout portion 18 and the band-shaped portion 20 in the solder land 10 portion. Since they are not adhered, the solder can be cut off from this portion and solder fogging can be prevented.

The shape of the cutout portion 18 is formed in a rectangular shape, but the lateral side c may be formed in a concentric shape along the through hole 9.

[Effect of device]

In the printed wiring board of the present invention, a cutout portion of the metal layer is formed so as to be continuous with the through hole of the solder land for retrofitting and wider than this through hole, and the exposed portion of the metal layer is formed at the edge portion of the through hole. Since it is possible to provide only a semicircle and a wide masking layer region covering the notch portion continuous to the through hole can be provided, solder fogging of the through hole can be reliably prevented. This is especially effective when the through hole has a small diameter.

Further, since the width of the strip-shaped portion of the masking layer of the solder land is narrower than that of the through hole, and the area of the metal layer to which the solder of the solder land to be brazed at the time of the later attachment is attached can be widened, so that a large solder strength can be realized.

Further, in this solder land, since the metal layer is continuous in the circumferential direction except for the through hole and the notch portion, a uniform temperature distribution in the solder land portion, which is an advantageous condition during brazing, can be obtained. The solder can be reliably attached.

[Brief description of drawings]

FIG. 1 is a partially enlarged plan view of a printed wiring board of the present invention according to an embodiment, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. FIG. 4 is a partial plan view showing an embodiment of the solder land of the present invention, FIG. 5 is a partially enlarged view of a conventional printed wiring board, and FIG. 6 is a V of FIG. It is a -V line sectional view. 1 ... Substrate, 2 ... Metal layer, 4 ... Masking layer, 8, 9
...... Through hole, 10,12 ...... Solder land, 18 ...... Notch part, 20 ...... Strip-shaped part.

Claims (1)

(57) [Scope of utility model registration request] 1. A metal layer (2) for brazing a printed circuit formed by etching a metal layer (2) on a substrate (1) and a circuit outside the printed circuit. A solder land (10) formed by etching is provided, and the solder land (10) has a through hole (9) penetrating the substrate (1) and inserting the connector. 9) A lateral side (a) enlarged in the diameter direction from the peripheral edge and a vertical side (b) directed toward the peripheral edge of the solder land (10).
And a lateral side (c) substantially parallel to the lateral side (a),
In addition, a notch (18) is formed so as to include a half circumference portion of the through hole (9), the notch (18) and the outer peripheral edge of the solder land (10) are connected to each other, and the through hole (9) is formed. A printed wiring board on which a masking layer having a strip-shaped portion (20) narrower than the width of () is formed.