JPH067272U - Printed circuit board for surface mount electronic components - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the occurrence of solder bridges in surface mount ICs. [Structure] In a surface mount type IC 21, a terminal row is projected on each of four side surfaces of a flat package. Here, the conductor lands 12 provided on the printed circuit board 11 for surface-mounting this surface-mount type IC include the conductor lands 12a assigned to the terminals located at both ends of the terminal row and the other conductor lands. It is larger than 12b. As a result, the position correction force acting on the IC 21 due to the surface tension of the solder can be increased, and thus even if there is a variation in the mounting position of the IC 21 on the printed circuit board 11, the occurrence of solder bridges can be suppressed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a surface mount type electronic component printed circuit board, and more particularly to a printed circuit board capable of avoiding generation of a solder bridge when surface mounting a surface mount type electronic component having a plurality of terminal rows protruding from a package.

[0002]

[Prior art]

 Conventionally, an electronic component such as a resistor or an IC is placed on a conductor land formed on a printed circuit board with its terminals aligned and soldered to the conductor land portion. Mounting is performed on the surface of the printed circuit board by a method called mounting.

Here, even if the terminal is slightly displaced from the conductor land and the surface mount type electronic component is placed on the conductor land, when the solder is melted in the surface mount step, the surface tension of the solder causes the terminal to move substantially into the conductor land. It is known that a correction force for moving to the center acts to cause a phenomenon called self-alignment in which the positional deviation is corrected. Therefore, even if there is a slight misalignment when the electronic component is placed on the printed circuit board, if the self-alignment phenomenon occurs, the misalignment can be corrected and the occurrence of solder bridge due to the misalignment can be avoided. It is a thing.

[0004]

[Problems to be solved by the device]

 However, when a relatively large multi-pin IC 21 having terminal rows 23a to 23d is surface-mounted on the four sides of the flat package 22 as shown in FIG. 2, the self-alignment phenomenon is caused by the weight of the IC. If the surface-mount type IC is placed with a displacement with respect to the conductor land, it will be soldered without being corrected and the solder bridge will be generated. was there.

In the self-alignment phenomenon, if the area of the conductor land is increased, a larger force acts on the terminal as a position correction force. However, in the surface mount type IC21 as shown in FIG. 2, it is difficult to secure a large space between the conductor lands because the terminal space is small. Even if there is no misalignment, the risk of causing solder bridges increases.

Therefore, the area of the conductor land cannot be simply increased to induce the self-alignment phenomenon. For the surface-mounted IC 21 as shown in FIG. 2, as shown in FIG. All the conductor lands 12 were formed on the printed board 11 in a size determined by the intervals. Therefore, it is not possible to secure a necessary and sufficient position correcting force when the solder melts, and solder bridging may occur due to variations in the mounting position of the electronic component on the printed circuit board.

The present invention has been made in view of the above problems, and even in the case of an electronic component having a short distance between terminals and a relatively heavy weight, the surface tension of the solder when the solder is melted causes the terminals to contact the conductor land. The objective is to effectively induce the phenomenon of straightening by moving it to approximately the center, and thereby significantly reducing the frequency of solder bridge occurrence during surface mounting.

[0008]

[Means for Solving the Problems]

 Therefore, the printed circuit board for surface-mounted electronic components according to the present invention is a printed circuit board on which surface-mounted electronic components having a plurality of terminal rows protruding from the package are surface-mounted, and is assigned to each terminal of the plurality of terminal rows. Among the conductive lands, the conductive lands assigned to the terminals at both ends of each terminal row are formed larger than the other conductive lands.

[0009]

[Action]

 In surface-mount electronic components in which multiple terminal rows protrude from the package, the size of the conductor land formed on the printed circuit board is limited by the distance between the terminals on both sides of the terminal row in the middle of the terminal row. Become. However, at the terminals at both ends of the terminal row, there is a margin in the direction in which the terminal row is interrupted, and even if the conductor land is increased by this margin, interference with adjacent terminals is avoided. It is possible.

Therefore, in the present invention, the conductor lands assigned to the terminals at both ends of each terminal row are formed larger than the other conductor lands, and the conductor lands can be made large even at both ends of the terminal row. For example, it is possible to increase the positional force generated by the surface tension of the solder when the solder is melted.

[0011]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a conductor land 12 provided on the surface of a printed circuit board 11 for mounting a surface mount type IC (surface mount type electronic component) of a flat package as shown in FIG.

In the surface mount type IC 21 shown in FIG. 2, terminal rows 23a to 23d are projected on each of four side surfaces of a substantially square flat package 22, and each terminal 24 constituting the terminal rows 23a to 23d is As shown in FIG. 3, the soldering surface parallel to the end surface of the flat package 22 is bent and formed so as to be constituted by the tip portion. The surface mount type IC 21 is mounted on the printed circuit board 11 so that the terminals 24 assigned to the respective conductor lands 12 are mounted, and then the terminals 24 are soldered to the conductor lands 12 respectively. Surface-mounted (surface-mounted) on the printed circuit board 11.

Here, the conductor lands 12 provided on the printed circuit board 11 corresponding to the terminal rows 23a to 23d of the surface mount IC 21 are conductors assigned to the terminals 24a at both ends of the terminal rows 23a to 23d. The land 12a is formed in a larger area than the conductor land 12b assigned to the terminal 24b sandwiched between the terminals on the other sides. That is, the conductor lands 12b assigned to the terminals 24b of the terminals 24 constituting each of the terminal rows 23a to 23d that are adjacent to the other terminals on both sides are adjacent to each other at a constant interval corresponding to the terminal interval. In order to maintain insulation from the conductor lands 12, it is necessary to form a relatively narrow width in the terminal row direction.

On the other hand, the terminals 24a at both ends of each of the terminal rows 23a to 23d are adjacent to another terminal at a narrow interval on one side in the terminal row direction, but there is no adjacent terminal on the other side. For this reason, the conductor land 12a corresponding to the terminal 24a has a margin to extend in the direction in which the terminal row is interrupted, and in the present embodiment, the extension is carried out and the conductor land 12b corresponding to the intermediate terminal 24b is provided. It is formed to have a wide width in the terminal row direction.

When the surface-mounting type IC 21 is surface-mounted by the conductor land 12 having such a configuration, the conductor lands 12a at the four corners (eight positions in total) have a larger area than the conductor land 12b regulated by the terminal spacing. In comparison with the case where all the conductor lands 12 are formed in the size of the conductor lands 12b, at least the conductor lands 12a having the large area can generate a larger position correcting force for the IC 21 when the solder is melted. .

Therefore, when the surface-mounting type IC 21, which is a relatively heavy electronic component, is surface-mounted as in this embodiment, even if the mounting position is displaced with respect to the conductor land 12, the comparative areas of the four corners are compared. The large positional correction force generated in the large conductor land 12a allows the positional deviation described above to be corrected. For this reason, even if the IC 21 is displaced on the printed circuit board 11 when it is displaced, it is possible to avoid soldering at the same position, so that the solder bridge caused by the displacement of the mounting position can be prevented. It becomes possible to suppress the occurrence.

When the area of the conductor land 12a corresponding to the terminals 24a at both ends of the terminal rows 23a to 23d is increased as compared with the other areas as described above, the ground plane of the terminal 24a is If the area is made larger than the others as shown in FIG. 4 like the conductor land 12a, even if the conductor land 12 has the same shape, the correction force of the mounting position due to the surface tension of the solder can be further increased. .

Further, the terminals of the surface mount IC 21 may have a shape as shown in FIG. 5 in addition to the shape as shown in FIG. 3, and the terminal shape is not limited. Further, in the surface mount IC 21 of this embodiment, the terminal row is projected on each of the four side surfaces of the substantially square flat package, but the terminal row is projected on each of the opposite longitudinal side surfaces of the rectangular flat package. In this case, a total of four conductor lands assigned to the terminals at both ends of each of the two terminal rows may be made larger than the other conductor lands.

[0019]

[Effect of device]

 As described above, according to the present invention, by devising the shape of the conductor land, it is possible to enhance the position correction force acting on the electronic component when the surface mounting solder is melted, and thus, the relatively heavy electron Even for parts, there is an effect that the position can be corrected and the occurrence of solder bridges can be avoided.

[Brief description of drawings]

FIG. 1 is a plan view showing a conductor land shape according to an embodiment.

FIG. 2 is a plan view showing a surface mount IC of the embodiment.

FIG. 3 is a partial vertical cross-sectional view showing a surface-mounted state of a surface-mounted IC.

FIG. 4 is a plan view showing another embodiment of the surface mount IC.

FIG. 5 is a partial vertical cross-sectional view showing another embodiment of the terminal shape of the surface mount IC.

FIG. 6 is a plan view showing a conventional conductor land shape.

[Explanation of symbols]

 11 Printed circuit board 12 Conductor land 21 Surface mounting IC 22 Flat package 23a-23d Terminal row 24 terminals

Claims (1)

[Scope of utility model registration request] 1. A printed circuit board on which surface-mounting electronic components, each of which has a plurality of terminal rows protruding from a package, are surface-mounted.
Among the conductor lands assigned to the terminals of the plurality of terminal rows, the conductor lands assigned to the terminals at both ends of each terminal row are formed to be larger than other conductor lands. Printed circuit board for electronic parts.