JPH0730241A - Printed board - Google Patents

Abstract

PURPOSE:To prevent malsoldering such as the generation of solder bridges, fractured solder joint, etc., by forming a plurality of lands whose breadth becomes wider in the order of an arranged direction, and performing soldering causing the direction of solder flow in a soldering apparatus to coincide with that of the extension of the land breadth. CONSTITUTION:Lands 2a-2f are formed so that their width shown in the vertical direction may be wider in the order of a direction opposite to a dipping direction, i.e., in the order of really passing the solder jetting part of a soldering apparatus. Incidentally, the distance between a land and the next in the dipping direction is not changed. By forming the lands 2a-2f into these shapes, solder is drawn to a rear land having wider soldering area and appropriate soldering can be performed, even if the flow of jetted melted solder stagnates between lands, when a printed board is soldered by a flow soldering apparatus, for example. Accordingly, it becomes possible to prevent malsoldering such as the generation of solder bridges, solder tubercles, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed board on which a wiring pattern such as a land made of copper foil is formed and various components are mounted, and a method for soldering to the printed board.

[0002]

2. Description of the Related Art When a package such as an IC or a component such as a connector in which leads and electrodes are linearly provided is mounted on a printed circuit board, a comparison is made corresponding to these electrodes and leads. Plural lands that are close to each other are formed in one direction. FIG. 4 is a plan view showing a part of such a printed circuit board.
2a to 2f formed on the surface of the lands indicate lands to which leads of components such as ICs and connectors are soldered. As can be seen from this figure, the lands 2a to 2f are formed side by side in one direction. Together, they all have similar sizes and shapes. Further, 3a to 3f show lead insertion holes into which leads of components are inserted from the back side of the printed circuit board in the figure.

In the figure, the arrow indicates that the printed circuit board 1 advances toward the solder jet portion of the soldering device and is dipped into the molten solder in the soldering process by flow soldering described below. The direction (hereinafter referred to as the dip direction) is shown. And usually land 2a
Lands to which leads such as ICs are soldered are formed along the dip direction of the substrate as shown in FIGS. That is, components such as ICs mounted on the board are arranged so that their leads extend along the dip direction. Thus, the molten solder jetted from the solder nozzle at the time of soldering can smoothly flow backward in the lower portion of the substrate.

The side view of FIG. 5 conceptually shows a step of soldering by flow soldering, which is mainly used for soldering components to be mounted by inserting leads into a board. In this figure, 4 indicates a component in which leads are linearly arranged, such as an IC, and the leads 5a to 5f of the component 4 are connected to the lead insertion holes 3a to 3f ( (Shown in FIG. 4) and is mounted on the printed circuit board 1 as shown in the figure. Further, 7 is a part of a soldering device capable of automatically performing soldering, showing a solder jet portion, and 8 is a solder nozzle for jetting molten solder.

In the solder jet section 7 of the soldering device, the molten solder is continuously jetted and flows from the solder nozzle 8 as indicated by the broken line arrow. When soldering the board, the printed board 1 on which the components are mounted is moved while being immersed in the solder flowing from the solder nozzle 8 in the dip direction indicated by the arrow. As a result, the lands 2a to 2f and the leads 5a to 5f of the component 4 are joined by soldering, and the component 4 is mounted on the printed board 1.

[0006]

By the way, as described above, the lands 2a to 2f are formed along the dip direction so that the molten solder ejected from the solder nozzle 8 can smoothly flow backward, but the surface is still formed. In some cases, the leads (5a to 5f) of the component 4 projecting to the side interfere with the flow of the molten solder and the breakage of the solder deteriorates. Further, since the lands 2a to 2f are formed at intervals corresponding to the leads of the IC or the like, the distance between the lands is relatively small. Due to such circumstances, a bridge of the solder 6 is highly likely to occur between the adjacent lands (in this case, the case between the lands 2e and 2f is shown) as shown in the side view of FIG. In addition, since more than an appropriate amount of solder may be deposited on one land, there is a high possibility that an improper soldering state called so-called solder will occur. When such a defect occurs, it is necessary to correct it later, and it takes extra time to complete the circuit board by the number of man-hours, and as a result, the production efficiency of the equipment using this printed circuit board also decreases. have.

[0007]

In order to solve the above problems, the present invention is directed to a printed circuit board in which a plurality of lands are formed side by side in one direction. The land width is made wider, and the solder is introduced into the soldering device so that the flow direction of the solder in the soldering device and the expansion direction of the land width of the land coincide with each other. .

[0008]

If the lands arranged in a row on the printed circuit board are formed so that the land width becomes gradually wider in accordance with the flow direction of the solder of the soldering device, it is possible to prevent defects such as bridges and solders of the solder. You can

[0009]

FIG. 1 is a plan view showing an embodiment of a printed circuit board according to the present invention. The same parts as those in FIG. 4 are designated by the same reference numerals and their explanations are omitted. It is supposed to indicate the direction. In this case, as shown in the figure, the lands 2a to 2f are in the opposite direction to the arrow indicating the dip direction, that is, in the order of actually passing through the solder jet part 7 of the soldering device, the lands 2a to 2f are orthogonal to the dip direction. The width shown in the direction) is wide. The distance between the lands in the dip direction is not changed. By forming the lands 2a to 2f in such a shape,
For example, if the printed circuit board of this embodiment is soldered by a flow soldering soldering apparatus as shown in FIG.
Even if the flow of the spouted molten solder stagnates between the lands, the solder is drawn into the land with a larger soldering area in the rear, so that proper soldering is performed and the bridge or potato solder It is possible to avoid such defects.

FIG. 2 is a plan view showing a printed circuit board of another embodiment. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, a land 2g having the same shape as the other lands and having a size larger than the land 2f is formed behind the land 2f in the dip direction of the printed circuit board 1. No lead insertion hole is formed in the land 2g because the lead or electrode of the component is not soldered. When the printed circuit board according to the present embodiment is soldered by the flow soldering soldering apparatus as shown in FIG. 5, the molten solder is drawn into the land 2g, so that the side surface of FIG. Since the lands 2a to 2f are properly soldered as shown in the figure, the possibility of defects such as bridges can be further reduced. Although the size of the land 2g is larger than that of the land 2f here, it is needless to say that the land 2g may be formed in an area smaller than that shown in FIG. 2 as long as the defective soldering can be sufficiently avoided. Absent.

By the way, the soldering by the flow soldering performed in each of the above-described embodiments is mainly performed on the substrate on which the lead component having the lead is mounted. In order to supplement the constants and characteristics that surface mount boards that are surface mounted or chip parts do not have, in addition to chip parts that are surface mounted, lead parts are also mixed and mounted on one board. There is a board. In such a surface mount board or a chip / lead component mixed board, for example, a reflow method is used as one means for mounting various parts on the board. This is done, for example, by first applying paste-like solder to the required parts of the pattern of the board, mounting the parts there, and then passing this board through a furnace at a predetermined temperature corresponding to the melting point of the solder by means of a belt conveyor. By doing so, the electrodes (or leads) of the components and the lands are soldered.

[0012] For example, in the above-mentioned reflow method, defects such as bridges may occur when soldering is performed in a furnace due to causes such as uneven application amount of paste-like solder and positional deviation. Therefore, the land of the printed circuit board to be soldered by the above-mentioned reflow method,
For example, if the width is changed according to the direction of the belt conveyor, the soldering failure can be prevented. In the reflow method, it is difficult to adjust the amount of paste-like solder applied to lands of different areas, so the amount of solder applied to the lands may be constant.
In such a case, the possibility of bridging increases, which is particularly effective.

Although the plurality of lands in each of the above-described embodiments are formed so as to correspond to the plurality of leads of one component such as an IC and a connector, for example, the lands corresponding to the leads of different components are dipped. The present invention is also applicable to the case where they are formed side by side close to each other in the direction. Further, the shape of each land is not limited to that shown in FIGS. 1 and 2 as long as it has the same effect as that of each of the above-mentioned embodiments, and it is also conceivable to make it an elliptical shape or the like. . Further, the soldering method is not limited to the above-described flow soldering or reflow method, and the solder flows relatively to the board surface even in a soldering method in which the board is immersed and moved in a molten solder bath. Therefore, it is effective to increase the land width according to this direction.

[0014]

As described above, according to the present invention, the widths of the lands arranged in one direction in the printed circuit board are gradually increased, and the land width of the printed circuit board is increased and the solder flow direction of the soldering device is increased. Since they are introduced into the soldering device so as to match with each other, there is an effect that it is possible to prevent a defect such as a solder bridge or potato solder when soldering is performed by an automatic soldering device. .
Therefore, the number of steps for correcting such a defective portion is reduced, so that the manufacturing efficiency of the circuit board and the product loaded with the board of the present invention can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing a part of a printed circuit board as an embodiment of the present invention.

FIG. 2 is a plan view showing a part of a printed circuit board as another embodiment of the present invention.

FIG. 3 is a side view showing, in a cross section, a state in which a printed circuit board according to another embodiment is soldered.

FIG. 4 is a plan view showing a part of a printed circuit board in a conventional example.

FIG. 5 is an explanatory view conceptually showing a soldering process.

FIG. 6 is a side view showing a state in which a solder bridge is generated between lands in a conventional example.

[Explanation of symbols]

 1 Printed Circuit Board 2a to 2g Land 3a to 3f Lead insertion hole 4 Components 5a to 5f Lead 6 Solder 7 Solder jet part 8 Solder nozzle

Claims (2)

[Claims] 1. A printed circuit board in which a plurality of lands are formed side by side in one direction, wherein the plurality of lands are formed such that the land width increases in the order in which they are arranged. . 2. A printed circuit board having a plurality of lands arranged side by side in one direction, so that the flow direction of the solder in the soldering device and the expansion direction of the land width of the plurality of lands are aligned with each other. The soldering method is characterized in that the soldering is performed by introducing the solder into