JPH0722747A - Printed circuit board - Google Patents

Abstract

PURPOSE:To inexpensively provide a printed circuit board where components can be mounted with a plurality of protuberances on one copper foil land. CONSTITUTION:A slit 2a is formed in nearly cross shape from the center of each side to a center in an etching stage at a rectangular copper foil land 2 of a printed circuit board 1. A solder protuberance 4 protrudes and is formed from each slit 2a so that the solder protuberance 4 may be divided into four parts. When the protuberance tops of the four semiconductor protuberances 4a, 4a, 4a, and 4a are connected, a plane is nearly formed. Therefore, when mounting chip components to the solder protuberance 4 of the printed circuit board 1 by the reflow soldering method, the chip components can be mounted easily on each solder protuberance 4a, thus improving soldering accuracy.

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 suitable for mounting surface mount components such as chip components by a reflow soldering method.

[0002]

2. Description of the Related Art For example, a reflow soldering method is known as a method for mounting a chip component on a printed circuit board. In this reflow soldering method, solder is previously supplied to a soldering portion of a printed circuit board, and the solder is melted and soldered by using a heat source such as hot air. FIG. 7 shows a process of soldering using cream solder printing by this reflow soldering method.
A specific description will be given with reference to (a) to (d). First, FIG.
As shown in FIG. 7B, cream solders 14 and 14 are printed on two copper foil lands 2 and 2 of a printed circuit board 1 formed by etching an electric circuit on a copper-clad laminate shown in FIG. To do. Next, as shown in FIG. 7C, after mounting the chip component 10 as the surface mount component on the cream solder 14, 14 at two places of the printed circuit board 1,
As shown in (d), the cream solder 14, 14 is melted and soldered using a heat source such as hot air.

However, in the reflow soldering mounting using the cream solder printing described above, a screen is required and the quality of the solder has an influence on the quality of the solder. Was affected, and it was difficult to obtain accuracy. In addition, there are various problems such as a change in print quality due to a subtle difference in printing conditions, and a limit in the control of biological cream solder and the leaving time after printing.

In order to deal with this, as a substitute for the solder supply by cream solder printing, a pre-coat soldering method (PS method) or a method of supplying solder in advance to a printed circuit board by solder plating or the like has begun to be adopted. Solder supply by this precoat soldering method is shown in FIG.
As shown in (a) and (b), a required amount of solder 4 is applied to the copper foil land 2 of the printed circuit board 1 in a saturated state by using a dip tank (not shown) or a dedicated precoating machine close thereto (solder precoating). It is a thing. In addition, as shown in FIG. 9A, the solder is supplied by solder plating. First, the flux 7 is applied to the printed circuit board 1, and then, as shown in FIG. After 1 is put and solder plating is performed on the entire surface, as shown in FIG. 9C, while the printed circuit board 1 is being pulled up, the rising solder plating is blown off by the hot air air knife 9 to supply solder. Reference numeral 3 in FIG. 8 is a resist and silk as a printed insulating film.

[0005]

However, in the solder supply by the precoat soldering method described above, when the copper foil land 2 of the printed board 1 is soldered in a saturated state, as shown in FIG. There is a problem that it is difficult to mount the chip component 10 because the swelling is large and the vertex has a spherical shape. Further, in the solder supply by the above-mentioned solder plating, in order to remove the rise of the solder, a step of blowing the solder away as shown in FIG. 9 (c) is necessary, which increases the cost.

Therefore, the present invention provides an inexpensive printed circuit board on which surface mount components can be mounted with high accuracy by soldering.

[0007]

In a printed circuit board formed by etching an electric circuit on a copper-clad laminate, a plurality of raised vertices or continuous points are generated on a copper foil land for soldering surface mount components. The solder deposits are formed so as to be divided and projected in a saturated state so that the points are connected to form a substantially flat surface.

[0008]

Since the plurality of solder bulges formed by the divided protrusions are formed so as to form a plane when connecting the apexes or the continuous points, it is easy to mount the surface mount component on each solder bulge, which is preferable. Soldering is performed.

[0009]

Embodiments of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a printed circuit board formed by etching an electric circuit on a copper clad laminate, each rectangular copper foil land 2 surrounded by a resist 3 as a printed insulating film.
In addition, the point that the solder 4 is soldered in a saturated state (solder precoating) using a dedicated precoating machine (not shown) or a dedicated precoating machine similar thereto is that solder supply by the conventional precoating soldering method (PS method) shown in FIG. It is similar to the case of.

Here, in the rectangular copper foil land 2, slits 2a are formed in a substantially cross shape from the center to the center of each side at the stage of etching. Each slit 2
A solder protrusion 4 is formed in a rectangular shape so as to be divided into four parts by a (projection portions of the same shape divided into four parts are indicated by reference numerals 4a, respectively). It is formed so as to form a substantially flat surface by connecting.

The step of mounting components by the reflow soldering method using this printed circuit board 1 will be specifically described with reference to FIGS. First, as shown in FIG. 6 (b), a solder layer 4 is provided on two copper foil lands 2 and 2 of a printed circuit board 1 formed by etching an electric circuit on the copper clad laminate shown in FIG. 6 (a). Four divided protrusions are formed (this portion is indicated by reference numeral 4a). Next, as shown in FIG.
As shown in (d), the solder paste 4a, 4a, 4a, 4a divided into four parts of the printed circuit board 1 has a high-viscosity flux 7.
And a chip component 10 as a surface mount component
After mounting, as shown in FIG. 6E, each solder layer 4a is melted and soldered by using a heat source such as hot air. The high-viscosity flux 7 serves to prevent the positional displacement of the mounted chip component 10 and the scattering of the flux 7.

When the chip component 10 is mounted on the solder pile 4 of the printed circuit board 1 by the reflow soldering method, it is formed so that the apexes of the respective solder piles 4a formed by the divided projection are connected to form a flat surface. The chip component 10 can be easily mounted on each of the solder pieces 4a, and the accuracy of reflow soldering can be improved. Further, since the amount of solder is determined by the shape of the copper foil land 2, the quality can be stabilized. Further, not only automation but also the same solder fill 4 can be done manually, so that line correction and service are easy.

As described above, by supplying the solder by the precoat soldering method, reflow soldering is performed by using the printed circuit board 1 on which the respective solder heaps 4a, which are divided into four, are formed on the copper foil land 2 so as to perform the reflow soldering. Therefore, it is possible to solve all problems associated with screens, cream solders, etc. by the reflow soldering method using the conventional cream solder printing. Further, since there is no restriction on the ease of releasing the cream solder, it is possible to deal with soldering with high component density. Furthermore, since the solder precoat in a saturated state is adopted in order to make the amount of supplied solder constant, that is, since the surface tension of the solder in a sufficiently active state is utilized, It is possible to stabilize the height of the solder heap and also to achieve the conventional
Since the step of blowing off the solder shown in (c) is unnecessary,
Therefore, it is possible to form the respective solder heaps 4 that are formed as the divided protrusions at a low cost.

According to the above-mentioned embodiment, the four solder slabs 4a, 4a, 4a, 4a are formed on the copper foil land 2 so as to project therefrom. However, another embodiment shown in FIGS. As shown in FIG.
You may form 4b and 4b by protrusion. In this case, a pair of parallel slits 2b, 2b are formed in the copper foil land 2 from one side to the other side opposite to each other at the etching stage, and one side is divided into three planes E long in one direction. Character-shaped solder heaps 4b, 4b, 4b are formed. As a result, the solder protrusions 4b formed as divided protrusions are formed so as to form a plane when three continuous linear vertices that are long in one direction are connected. Therefore, as in the case of the solder protrusions 4a, the chip component is formed. The 10 can be easily placed, and the accuracy of reflow soldering can be improved.

Further, as in another embodiment shown in FIGS. 3A and 3B, the solder deposit 4 having the same four-divided rectangular shape is formed.
The portions c, 4c, 4c, 4c may be covered and separated by a cross-shaped portion 3c of the resist 3 as a printed insulating film, and still another embodiment shown in FIGS. 4 (a) and 4 (b). As shown in FIG.
The portions 3d, 4d, 4d, 4d, 4d may be separated by being covered with a portion 3d of the resist 3 as a printed insulating film, and still another mode shown in FIGS. 5 (a) and 5 (b). As described above, the solder pastes 4e, 4e, 4e having the same shape elongated in one direction and elongated in one direction may be covered and separated by the portions 3e, 3e of the resist 3 as a printed insulating film. .

In the case of FIG. 3 and FIG. 4, the solder protrusions 4c and 4d are formed so as to be flat when the apexes of the divided solder protrusions 4c and 4d are connected, and in the case of FIG. Since three continuous linear vertices that are long in one direction are connected to form a flat surface, the solder deposits 4a
Similarly to the case of (3), the chip component 10 can be easily placed, and the accuracy of reflow soldering can be improved.

[0018]

As described above, according to the present invention, in a printed circuit board formed by etching an electric circuit on a copper-clad laminate, a plurality of raised peaks or ridges are formed on a copper foil land for soldering surface mount components. When soldering surface-mounted components to the copper foil lands of the printed circuit board, the solder ridges are formed so that they are saturated so that continuous points occur, and they are formed so that they are almost flat when the points are connected. In addition, it is easy to mount the surface-mounted component on each of the solder protrusions formed by the divided projection, and it is possible to perform soldering with high accuracy.

[Brief description of drawings]

FIG. 1A is a plan view of an essential part of a printed circuit board having divided solder deposits showing an embodiment of the present invention, and FIG.

FIG. 2A is a plan view of a main part of a printed circuit board having a divided solder deposit of another embodiment, and FIG.

FIG. 3A is a plan view of a main part of a printed circuit board having a divided solder deposit of another mode, and FIG. 3B is a sectional view of the same.

FIG. 4A is a plan view of a main part of a printed circuit board having a divided solder layer according to still another embodiment, and FIG.

FIG. 5A is a plan view of a main part of a printed circuit board having a divided solder paste according to still another embodiment, and FIG.

6A to 6E are explanatory views sequentially showing a step of component mounting by a reflow soldering method using the printed board.

7A to 7D are explanatory views sequentially showing a step of mounting components by a reflow soldering method using cream solder printing of a conventional example.

FIG. 8A is a plan view of a main portion of a printed circuit board to which solder has been supplied by a conventional precoat soldering method, and FIG.
Is the same sectional view.

9A to 9C are explanatory views sequentially showing the supply of solder to a printed circuit board by conventional solder plating.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Printed circuit board 2 ... Copper foil land 2a, 2b ... Slit 3 ... Printed insulating film 4 ... Solder pile 4a-4e ... Divided solder pile 10 ... Mounting component

Claims (5)

[Claims] 1. A printed circuit board obtained by etching an electric circuit on a copper-clad laminate, and soldered to a saturated state so that a plurality of raised vertices or continuous points are generated on a copper foil land for soldering surface mounting components. A printed circuit board, characterized in that a hemisphere is formed so as to be divided and projected to form a substantially flat surface when the points are connected. 2. The printed circuit board according to claim 1, wherein
A printed circuit board, characterized in that one copper foil land is divided by slits formed at the etching stage, and the above-mentioned solder deposit is divided and projected. 3. The printed circuit board according to claim 2, wherein
A printed circuit board, characterized in that when each of the solder protrusions formed in the above-mentioned divided projection is rectangular, the dimension of each side is the same at least on the short side. 4. The printed circuit board according to claim 1, wherein
A printed circuit board, characterized in that one copper foil land is separated by a printed insulating film, and the above-mentioned solder deposit is formed in a divided manner. 5. The printed circuit board according to claim 1,
A printed circuit board, characterized in that when each of the solder protrusions formed in the above-mentioned divided projection has a circular shape, the diameter is the same.