JPH05129767A - Printed wiring board - Google Patents

Abstract

PURPOSE:To enhance a printed wiring board in soldering reliability by a method wherein solder bridges are prevented from occurring between mounting lands. CONSTITUTION:A printed wiring board 11 is provided with an insertion hole 12 where a lead terminal of a component such as an IC or the like is inserted and a mounting land 13 provided around the insertion hole 12, where solder bridge preventing parts 15 are provided to, at least, one of the mounting lands 13 provided adjacent to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board suitable for mounting components such as ICs having lead terminals at extremely small pitch intervals.

[0002]

2. Description of the Related Art A printed wiring board on which components having lead terminals are mounted at extremely small pitch intervals, such as conventional ICs, for example, lead terminals having a pitch interval of 1.778 mm.
DIP (Dual In-line Packg)
A printed wiring board on which the e) type shrink IC is mounted will be described with reference to FIG.

In a conventional printed wiring board, an insertion hole 2 for inserting a lead terminal (not shown) of a DIP type shrink IC is provided in an insulating substrate 1, and the DIP is provided around the insertion hole 2.
A circular mounting land 3 for soldering a lead terminal (not shown) of a die-type shrink IC is provided, and a soldering resistance layer called solder resist having a plurality of mounting lands 3 and leaving the plurality of mounting lands 3 all over. 4 is formed by printing, and a solder bridge preventing soldering resistance layer 5 is further formed by printing between the mounting land 3 on one side and the mounting land 3 on the other side.

In the above structure, the center-to-center distance 6 of the insertion hole 2 is 1.778 mm, which is the same as the pitch interval of the lead terminals (not shown) of the DIP type shrink IC, and the hole diameter 7 of the insertion hole 2 is The land diameter 8 of the mounting land 3 is 0.7 mm, and the space 9 between the one mounting land 3 and the other mounting land 3 is 0.278 mm.

When a DIP type shrink IC is mounted on the printed wiring board having the above structure, the D
A lead terminal (not shown) of the IP type shrink IC is inserted into the insertion hole 2, and then a lead terminal (not shown) of the DIP type shrink IC is soldered to the mounting land 3 by solder dip. However, the solder is separated by the solder bridge preventing soldering resistor layer 5 between the one mounting land 3 and the other mounting land 3 to prevent the solder bridge between the one mounting land 3 and the other mounting land 3. It will be done.

[0006]

However, in the conventional printed wiring board, when printing is performed by covering the mounting land with the solder bridge preventing soldering resistance layer displaced in position, the solderability on the mounting land is poor. In addition, when printing of the solder bridge preventing soldering resistance layer is incomplete, a solder bridge between the mounting lands often occurs, resulting in poor soldering reliability.

[0007]

A printed wiring board according to the present invention comprises a solder bridge prevention portion on at least one of mounting lands.

[0008]

In the printed wiring board according to the present invention, the solder bridge prevention portion provided on the mounting lands can maintain a sufficient distance between the mounting lands, so that the solder bridges between the mounting lands can be reliably prevented. can do.

[0009]

EXAMPLES A printed wiring board for mounting components having lead terminals at extremely small pitch intervals such as the IC of the present invention, for example, a DIP (Dual In-Line Packg) in which the pitch intervals of the lead terminals are 1.788 mm.
An embodiment of a printed wiring board on which the e) type shrink IC is mounted will be described with reference to FIGS.

The printed wiring board of the present invention is an insulating substrate 1.
1 is a lead terminal of the DIP type shrink IC (not shown)
Is provided with a mounting land 13 for soldering a lead terminal (not shown) of the DIP-type shrink IC, and the mounting land 13 is provided around the insertion hole 12.
And a plurality of mounting lands 13 are left, and a soldering resistance layer 14 called a solder resist is printed and formed on the entire surface, and the one mounting land 13 and the other mounting land 13 are adjacent to each other. Is provided with a solder bridge prevention portion 15 formed by printing the soldering resistance layer 14 thereon.

In one embodiment of the present invention, the mounting lands 13 are arranged side by side in a row, so that the solder bridge prevention portion 15 is connected to the mounting lands 13 on both sides of the mounting land 13. It is provided at intervals of 180 ° in the adjacent portions. Further, the dimension value in the above configuration is such that the center distance 16 of the insertion holes 12 is 1.778 mm, which is the same as the pitch interval of the lead terminals (not shown) of the DIP type shrink IC, and the hole diameter 17 of the insertion holes 12 is 0.7 mm, the land diameter 18 of the mounting land 13 is 1.5 m
m, one mounting land 13 and the other mounting land 13
The space 19 between them is 0.278 mm.

When a DIP type shrink IC is mounted on the printed wiring board having the above-mentioned structure, the D
A lead terminal (not shown) of the IP type shrink IC is inserted into the insertion hole 12, and then a lead terminal (not shown) of the DIP type shrink IC is soldered to the mounting land 13 by solder dip. However, since the solder bridge prevention portions 15 provided in the portions of the one mounting land 13 and the other mounting land 13 that are close to each other can sufficiently maintain the distance between the mounting lands 13.
The solder bridge between the mounting lands 13 is prevented.

Next, when the length 20 in the normal direction of the mounting land 13 of the solder bridge prevention portion 15 is set to 0.3 mm, the solder bridge to the tangential length 21 of the mounting land 13 of the solder bridge prevention portion 15 is set. As shown in FIG. 3, the mounting land 1 of the solder bridge prevention portion 15
When the tangential length 21 of 3 is 0 mm, that is, when the solder bridge preventing portion 15 is not provided, 100% (128
While solder bridges are generated between 128 of the mounting lands 13 at the locations, about 20% (128 of the solder lands) when the tangential length 21 of the mounting land 13 of the solder bridge prevention portion 15 is 0.1 mm. 23 out of 13 mounting lands
Location) A solder bridge occurs, and the tangential length 21 of the mounting land 13 of the solder bridge prevention portion 15 is 0.2 mm.
In this case, the solder bridge occurrence rate was 0% (0 out of 128 mounting lands 13), and it can be seen that the solder bridge can be reliably prevented.

Further, in the above-mentioned one embodiment, the soldering resistance layer is provided by printing the soldering resistance layers on the portions of the mounting land adjacent to each other to prevent the soldering bridge. Regarding the case where the solder resistance layer is formed by printing as in the conventional example,
Another embodiment of the printed wiring board of the present invention will be described with reference to FIG.

The same parts as those in the above-described embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In the printed wiring board of the present invention, when the conductive pattern is formed by etching or the like, the solder bridge prevention portion 22 is formed by notching the portions of the one mounting land 13 and the other mounting land 13 which are close to each other. Since the solder bridge prevention portion 22 can maintain a sufficient distance between the mounting lands 13, the solder bridge preventing portions 22 prevent the solder bridges between the mounting lands 13.

[0017]

In the printed wiring board of the present invention, the solder bridge prevention portion provided on the mounting lands can maintain a sufficient distance between the mounting lands, so that the solder bridges between the mounting lands can be securely connected. Can be prevented,
It is possible to improve the reliability of soldering.

[Brief description of drawings]

FIG. 1 is an enlarged explanatory view of a main part showing an embodiment of a printed wiring board according to the present invention.

FIG. 2 is a schematic plan view showing an embodiment of the printed wiring board of the present invention.

FIG. 3 is an explanatory diagram showing a solder bridge generation rate with respect to a tangential length of a mounting land of a solder bridge prevention portion of one embodiment of a printed wiring board of the present invention.

FIG. 4 is an enlarged explanatory view of a main part showing another embodiment of the printed wiring board according to the present invention.

FIG. 5 is an enlarged explanatory view of a main part showing a conventional printed wiring board.

[Explanation of symbols]

 11 Insulating Substrate 12 Insertion Hole 13 Mounting Land 15, 22 Solder Bridge Preventing Section

Claims (1)

[Claims] 1. An insulating substrate is provided with an insertion hole into which a lead terminal of a component such as an IC is inserted, a mounting land is provided around the insertion hole, and a plurality of mounting lands are provided and the mounting lands are close to each other. A printed wiring board comprising a solder bridge prevention portion on at least one of the plurality of mounting lands.