Printed circuit board

Abstract

Disclosed herein is a printed circuit board that allows a wiring pattern to be resistant to noise while maintaining solderability even in the case where a wiring pattern is drawn out from the lower part of a QFP. A printed circuit board on which a QFP is mounted by dip soldering is provided with two separate solder flow lands formed between a front soldering land group and a rear soldering land group and a wiring pattern formed between the two separate solder flow lands, wherein the wiring pattern is a land having a width of not less than 0.3 mm, and a space between the wiring pattern and the solder flow lands is not less than 0.4 mm nor more than 0.8 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings,

FIG. 1 is an explanatory view showing the vicinity of solder flow lands of a printed circuit board according to embodiment 1 of the present invention;

FIG. 2 is an explanatory view showing the vicinity of solder flow lands of a printed circuit board according to embodiment 2 of the present invention;

FIG. 3 is an explanatory view showing the vicinity of a portion, used as a solder flow land, of a wiring pattern on a printed circuit board according to embodiment 3 of the present invention;

FIG. 4 is a perspective view of a QFP;

FIGS. 5A, 5B and 5C are explanatory views showing the dimensions of the QFP;

FIG. 6 is an explanatory view showing a conventional printed circuit board; and

FIG. 7 is an explanatory view showing the vicinity of solder flow lands in the case where a wiring pattern is conventionally drawn out from the lower part of the QFP.

Claims

1. A printed circuit board having a front soldering land group for soldering two terminal groups embracing a front corner of a QFP (Quad Flat Package) and a rear soldering land group for soldering two terminal groups embracing a rear corner opposite to the front corner to mount the QFP by dip soldering, the front corner being a corner put forward of the QFP and the rear corner being a corner opposite to the front corner put rearward with respect to a predetermined dip direction, the printed circuit board comprising: two separate solder flow lands formed between the front soldering land group and the rear soldering land group; anda wiring pattern formed between the two separate solder flow lands,wherein the wiring pattern is a land having a width of not less than 0.3 mm, and a space between the wiring pattern and the solder flow lands is not less than 0.4 mm nor more than 0.8 mm.

2. A printed circuit board having a front soldering land group for soldering two terminal groups embracing a front corner of a QFP and a rear soldering land group for soldering two terminal groups embracing a rear corner opposite to the front corner to mount the QFP by dip soldering, the front corner being a corner put forward of the QFP and the rear corner being a corner opposite to the front corner put rearward with respect to a predetermined dip direction, the printed circuit board comprising: two separate solder flow lands formed between the front soldering land group and the rear soldering land group; anda plurality of wiring patterns formed between the two separate solder flow lands,wherein one of the plurality of wiring patterns has a width of not less than 0.2 mm nor more than 0.25 mm and is coated with resist, a wiring pattern other than the resist-coated wiring pattern is a land having a width of not less than 0.3 mm, a space between the resist-coated wiring pattern and the adjacent lands is not less than 0.2 mm nor more than 0.25 mm, and a space between the lands is not less than 0.4 mm nor more than 0.8 mm.

3. A printed circuit board having a front soldering land group for soldering two terminal groups embracing a front corner of a QFP and a rear soldering land group for soldering two terminal groups embracing a rear corner opposite to the front corner to mount the QFP by dip soldering, the front corner being a corner put forward of the QFP and the rear corner being a corner opposite to the front corner put rearward with respect to a predetermined dip direction, the printed circuit board comprising: a wiring pattern formed between the front soldering land group and the rear soldering land group,wherein a portion of the wiring pattern being a land, a space between the land portion of the wiring pattern and the front soldering land group is not less than 0.4 mm nor more than 0.8 mm, and a space between the land portion of the wiring pattern and the rear soldering land group is not less than 0.4 mm nor more than 0.8 mm.