JP2000244080A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform cream soldering simultaneously with a part mounting pattern by performing cream solder printing on the surface of an earth land and then performing soldering in a reflow furnace. SOLUTION: A plurality of screw holes 1b for fastening a printed wiring board 1 mounting a surface mounting part 3 are made at corner parts and screws 4 are inserted into the screw holes 1b thus securing the printed wiring board 1 to the chassis (a), or the like, in an apparatus through a spacer 5. A ground pattern 6 is provided at a part of a circuit pattern 2 on the surface mounting part 3 side and an ground land 6a interconnected with an earth pattern 6 is provided around the screw hole 1b. A cream solder 7 is printed on the surface of the ground land 6a and soldering is performed in a reflow furnace. Since cream soldering is performed simultaneously with a part mounting patter without solder plating the earth land 6a, a printed wiring board advantageous in terms of cost is obtained.

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, and more particularly to a structure for soldering an earth land around a screw hole fixed to a chassis or the like by screwing.

[0002]

2. Description of the Related Art A conventional printed wiring board is shown in FIG.
As shown in FIGS. 1A and 1B, the printed wiring board 11 forms a circuit pattern 12 on the front and back surfaces of a base material 11a made of, for example, a glass epoxy resin by subjecting a copper foil to processing such as etching. At the same time, a through hole (not shown) for interconnecting the front and back circuit patterns 12 is formed. Cream solder 17 is printed on at least one side of the circuit pattern 12 of the printed wiring board 11, and a chip type semiconductor element, a resistor, a surface mount component 13 such as a capacitor is provided.
Is mounted and soldered and mounted through a reflow furnace.

The printed wiring board 11 on which the surface mount component 13 is mounted has a plurality of screw holes 11 fixed by screws.
b is provided at, for example, a corner portion, a screw 14 is inserted into the screw hole 11b, and is fixed to a chassis a or the like in the device via a spacer 15. An earth pattern 16 is provided on a part of the circuit pattern 12 on the surface mount component 13 side, and an earth land 16a communicating with the earth pattern 16 is provided around the screw hole 11b.

In the above-mentioned structure, the surface of the earth land 16a is subjected to a solder plating treatment 18 in order to prevent corrosion and to make a reliable earth connection with the chassis a. However, the solder plating process 18 has a problem that processing cost is high and disadvantageous in cost.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and does not perform solder plating on an earth land around a screw hole to be fixed to a chassis or the like by tightening a screw. At the same time, an object of the present invention is to provide a printed wiring board which is soldered by cream solder and is cost-effective.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an earth land is provided on a printed wiring board having a screw hole to be fixed by screwing around the screw hole. A screw is inserted through the screw hole, and the earth land is grounded to a chassis or the like by tightening the screw. After performing cream solder printing on the surface of the earth land, soldering is performed by a reflow furnace. It is configured to perform processing.

Further, the printed wiring board is formed of a double-sided printed board, and the ground land is provided on the component mounting surface side.

In addition, the cream solder printing of the ground land is simultaneously performed with the cream solder printing on the component mounting pattern.

Further, the cream solder printed portion of the earth land is formed in a chrysanthemum shape.

[0010] Further, the cream solder printed portion of the earth land is formed in a plurality of small circles.

Further, a resist is applied to a pattern portion other than the cream solder printed portion.

Further, a metal spacer is interposed between the screw hole of the printed wiring board and the chassis.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below as examples based on the attached drawings. FIG. 1 shows an embodiment of an earth land of a printed wiring board according to the present invention.
(A), FIG. 1 (B), FIG. 2 (A) and FIG. 2 (B). In the figure, reference numeral 1 denotes a printed wiring board, and the printed wiring board 1 is a circuit pattern 2 which is formed by etching and processing copper foil on both front and back surfaces of a substrate 1a having an insulating property, for example, a glass epoxy resin. And a through hole (not shown) for interconnecting the front and back circuit patterns 2 is formed. The printed wiring board 1 has a configuration in which a surface-mounted component 3 such as a chip-type semiconductor element, a resistor, and a capacitor is mounted on at least one surface of the circuit pattern 2.

The printed wiring board 1 on which the surface mount components 3 are mounted has a plurality of screw holes 1b which are fixed by screwing.
Is provided in, for example, a corner portion, a screw 4 is inserted into the screw hole 1b, and is fixed to a chassis 4 or the like in the device via a spacer 5. A ground pattern 6 is provided on a part of the circuit pattern 2 on the surface mount component 3 side, and the screw hole 1b is provided.
Around the ground pattern 6 is provided.

After the cream solder printing 7 is performed on the surface of the earth land 6a, a soldering process is performed in a reflow furnace. In addition, the cream solder printing 7 of the ground land 6a is performed simultaneously with the cream solder printing 7 on the circuit pattern 2 of the surface mount component 3, and the reflow furnace soldering process is also performed at the same time.

As shown in FIG. 2A, by forming the cream solder printing of the earth land 6a in a chrysanthemum shape, the thickness of the solder is uniformly finished.
When the screw is tightened, the flange of the screw 4 and the ground land 6a are sufficiently adhered to each other, so that a reliable ground can be obtained. Further, as shown in FIG. 2 (B), when the cream solder printing 7 of the earth land 6a is formed in a plurality of small circles, a reliable earth can be obtained as described above. A resist is applied to the portion of the earth land 6a where the cream solder printing 7 is not performed, so that the solder does not spread during reflow.

In the above configuration, when a ground land 6a is provided around the screw hole 1b for fixing the printed wiring board 1 by screwing, and the ground land 6a is grounded to the chassis 4 or the like by the screw tightening, After the cream solder printing 7 is performed on the surface of the earth land 6a, the solder processing is performed by a reflow furnace, so that the earth land is not subjected to the solder plating processing as in the conventional example. This is a printed wiring board that is economically advantageous.

[0018]

As described above, according to the present invention,
An earth land is provided around the screw hole for fixing the printed wiring board by screw tightening.
After applying cream solder printing to the surface of the land, the soldering process is performed in a reflow furnace. It becomes a wiring board.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a main part showing an embodiment according to the present invention;
(A) is a top view of an earth land, (B) is a sectional view of a main part showing an example of assembling a printed wiring board and a chassis.

FIGS. 2A and 2B are enlarged top views of a main part showing a shape of a cream solder printed portion of an earth land according to the present invention, wherein FIG. 2A is one embodiment and FIG.

FIG. 3 is an enlarged view of a main part according to a conventional example.
FIG. 4B is a top view of the land, and FIG. 4B is a cross-sectional view of a main part showing an example of assembling the printed wiring board and the chassis.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed wiring board 1a Substrate 1b Screw hole 2 Circuit pattern 3 Surface mount component 4 Chassis 5 Screw 6 Ground pattern 6a Ground land 7 Cream solder

Claims (7)

[Claims] 1. A printed wiring board having a screw hole to be fixed by screwing, a ground land is provided around the screw hole, a screw is inserted into the screw hole, and the ground land is tightened by the screw. A printed wiring board which is grounded to a chassis or the like by performing cream solder printing on the surface of the earth land and then performing a soldering process in a reflow furnace. 2. The printed wiring board according to claim 1, wherein said printed wiring board comprises a double-sided printed board, and said ground land is provided on a component mounting surface side. 3. The printed wiring board according to claim 1, wherein the cream solder printing of the ground land is performed simultaneously with the cream solder printing on a component mounting pattern. 4. The printed solder paste portion of the earth land is formed in a chrysanthemum shape.
The printed wiring board as described. 5. The printed wiring board according to claim 1, wherein a cream solder printed portion of said earth land is formed in a plurality of small circles. 6. The printed wiring board according to claim 1, wherein a resist is applied to a pattern portion other than the cream solder printed portion. 7. The printed wiring board according to claim 1, wherein a metal spacer is interposed between the screw hole of the printed wiring board and the chassis.