JPH0758427A - Printed wiring board - Google Patents

Abstract

PURPOSE:To effectively avoid a solder bridge between a solder land part and a through hole by a method wherein printing with a specific width is performed with an ink on a board surface surrounding a land part or a circuit pattern. CONSTITUTION:A surface of a through hole 3a containing a circuit pattern 2 that is not used as a solder land and both surfaces of a board 1 that the circuit pattern 2 is not formed are coated with an insulating solder resist ink 7. Therefore, a silk ink 6 is printed and simultaneously part number letters of a land part 5 are printed thereon. The surface of the through hole 3a that is not used as a solder land is coated and also a hole part 30a is blocked up with a solder resist ink 7 and the silk ink 6 is printed therefrom. Accordingly, the through hole 3a is insulation-sealed and a bridge between a solder land part 4 and the through hole 3a in the vicinity thereof can be more positively avoided than when only a conventional resist ink 7 is used.

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 on which an electronic component such as an IC can be mounted. More specifically, when soldering an electronic component to a solder land portion, a solder land portion and a through hole around the land portion are formed. The present invention relates to a printed wiring board that avoids the occurrence of a solder bridge between the two.

[0002]

2. Description of the Related Art An example of a conventional printed wiring board of this type is shown in FIG. Reference numeral 1 indicates a substrate on which printed wiring is formed, and 2
Is a circuit pattern printed and wired on the substrate 1. Reference numeral 3 is a through hole used as a solder land which is a part of the circuit pattern 2. Reference numeral 3a is a through hole not used as a solder land. Reference numeral 4 is a mounting component such as a shield. 3 shows a solder land portion on which an electronic component including a case is mounted.
Further, numeral 5 is a land portion of a chip component mounted on the circuit pattern 2, and characters of the component number are printed on the respective land portions 4 and 5 by silk printing with silk ink 6a.

By the way, the mounting of the electronic component on the solder land portion 4 described above may be carried out by manual soldering. At this time, a part of the solder adhered to the solder land portion 4 adheres in a bridge state to the through holes 3a not used as solder lands around the solder land portion, and as a result, the solder land portion 4 and the through hole 3a. There was a problem such as a short circuit.

As a measure for eliminating the solder bridge generated between the solder land portion 4 and the through hole 3a around the land portion,

A. The solder land portion 4 and the surrounding through hole 3a are separated by 2 mm or more. b. The surface of the through hole 3a and the front and back surfaces of the substrate 1 on which the circuit pattern is not formed are covered with resist ink. Etc. were generally done.

[0006]

However, the above-mentioned a. 2m between the solder land 4 and its surroundings
If the circuit pattern on the printed wiring board is super-dense, the printing space for the circuit pattern may be restricted and the circuit pattern may not be drawn if the distance is more than m.

Also, b. In the method of coating the surface of the through hole 3a with the resist ink as described above, the resist ink 7 is not coated on the edge portion 30 of the through hole 3a as shown in FIG. 4, or one side of the wiring board is a substrate manufacturing process. Therefore, the resist ink 7 may become thin, and as a result, the insulating effect may not be guaranteed for the solder bridge state between the solder land portion 4 and the through hole 3a.

The present invention has been made to solve the above-mentioned problems, and provides a printed wiring board which can effectively avoid a solder bridge between a solder land portion and a through hole. With the goal.

[0009]

In order to achieve the above-mentioned object, the printed wiring board according to the present invention is an ink for printing characters or the like on the board surface or circuit pattern around the land portion for soldering. The printing of a predetermined width is performed.

In a preferred embodiment of the present invention, the circuit pattern is a through hole.

In a preferred embodiment of the present invention, a solder resist ink layer is formed between the surface of the substrate or the circuit pattern and the printing ink, and the solder resist ink closes the through holes. .

Further, as a preferred embodiment of the present invention, printing ink such as characters is printed by silk screen printing.

[0013]

The printed wiring board according to the present invention having the above-described structure is capable of performing printing with a predetermined width using ink for printing characters or the like on the board surface around the land portion for soldering or on the circuit pattern. Therefore, the land portion and other circuit patterns around the land portion are insulated by the ink layer, and the short-circuit state due to the solder bridge can be avoided.

[0014]

Embodiments of the printed wiring board according to the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of an example of a printed wiring board of this example, FIG. 2 is an enlarged cross-sectional view of a main part of the printed wiring board, and the same parts as those of the conventional example described in FIGS. The overlapping description will be omitted.

In FIG. 1, the solder land portion 4 is used in the present invention.
The insulating silk ink 6 is printed by a so-called silk screen printing method in which characters and the like are printed around a predetermined width. The silk ink 6 has a relatively high viscosity, and an alkali-soluble vinyl ink is used as an example.

In the present embodiment, the silk ink 6 is printed over a printing width of 2 mm or more around the solder land portion 4. Therefore, the surface of the through hole 3 a that is not used as a solder land around the solder land portion 4 is also covered with the silk ink 6.

In the printing of the silk ink 6 described above, the surface of the through hole 3a including the circuit pattern 2 other than that used as a solder land and the circuit pattern 2 are not actually formed on the substrate 1. Since the front and back surfaces are generally covered with an insulating solder resist ink, the silk ink 6 is printed on the solder resist ink 7 simultaneously with the printing of the part number character of the land portion 5 of the chip part. A sectional view of the substrate 1 in this state is shown in FIG.

That is, the hole 30a is covered with the solder resist ink 7 together with the coating of the surface of the through hole 3a which is not used as a solder land, and the silk ink 6 according to the present invention is printed on the surface of the solder resist ink 7.

As described above, the printed wiring board according to the present invention is
Around the solder land 4 and the through hole 3 around it
By printing the silk ink 6 on a, the through hole 3a is insulated and sealed, and in the soldering work of the electronic component to the solder land portion 4, the solder land portion 4 and the through hole 3a around it are The bridge (short-circuited state) can be more surely avoided as compared with the case of the conventional resist ink 7.

Further, by printing the area of about 2 mm around the solder land portion 4 with the silk ink 6, even when the position of the through hole 3a carelessly approaches the solder land portion 4 when the circuit pattern is changed, Solder land 4 and through hole 3
The bridge with a can be avoided as above.

The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications can be made without departing from the spirit of the invention.

[0022]

As described above, the printed wiring board according to the present invention is printed with a predetermined width using ink for printing characters or the like on the surface of the board or the circuit pattern around the land for soldering. Since this is done, there is an effect that it is possible to surely avoid the bridge state between the solder land portion and the through hole around the solder land portion when soldering the chip component to the solder land portion.

Further, by printing a predetermined area around the solder land portion with ink for printing characters or the like, even if the position of the through hole is carelessly approached to the solder land portion when changing the circuit pattern, the solder The bridge between the land and the through hole can be similarly avoided.

[Brief description of drawings]

FIG. 1 is a plan view of a printed wiring board of this example.

FIG. 2 is an enlarged cross-sectional view of a main part of the printed wiring board of this example.

FIG. 3 is a plan view of a conventional printed wiring board.

FIG. 4 is an enlarged cross-sectional view of a main part of a conventional printed wiring board.

[Explanation of symbols]

 1 substrate 2 circuit pattern 3,3a through hole 4 solder land 6,6a silk ink 7 solder resist ink

Claims (4)

[Claims] 1. A circuit having a predetermined width is printed with ink for printing characters or the like on a substrate surface or a circuit pattern around a solder land portion for soldering, and the solder land portion and other circuits around the solder land portion. A printed wiring board characterized in that no solder bridge is formed between the pattern and the solder bridge. 2. The printed wiring board according to claim 1, wherein the circuit pattern is a through hole. 3. A solder resist ink layer is formed between the substrate surface or circuit pattern and the printing ink, and the solder resist ink closes the through hole. The printed wiring board according to claim 2. 4. The printed wiring board according to claim 1 or 3, wherein the printing ink such as the characters is printed by silk screen printing.