JPH05342304A - Printed board cad system - Google Patents

Abstract

PURPOSE:To design a printed board in a short time by correctly recognizing the wiring density in each area of a wiring pattern on the printed board. CONSTITUTION:A step B for temporary wiring, a step F where the printed board is divided into plural areas, a step G where lattices are vertically and horizontally arranged in each of divided areas at intervals corresponding to an allowable wiring density, a step H where the number of lattices scattered in each of divided areas is counted, a step I where the number of lattices included in the wiring in each of divided areas is counted, and a step J where the number of lattices counted in the step I is divided by that counted in the step H to calculate the wiring density are provided besides steps A to D where parts are arranged on the printed board based on wiring density forecast of rat's nest information, and the wiring density in each area is displayed in a step L, thus making the degree of congestion of wiring easy to understand.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board CA for designing the layout and wiring of components mounted on the printed circuit board.
The present invention relates to a D (Computer Aided Design) system.

[0002]

2. Description of the Related Art FIGS. 2A and 2B are a flowchart for explaining an example of a conventional printed board CAD system and a part of a printed board drawn on a display. Conventionally, a printed board CAD system of this type is, for example, performed based on the flowchart shown in FIG.

The printed board CAD system is as follows.
In step A shown in FIG. 2A, information regarding the external dimensions of the printed board and the components mounted on the printed board and the terminals to be wired is input. Next, in step B, the parts are arranged on the printed board. Next, in step C, based on the net information called rat nest, the connection terminals of each component are connected and drawn on the display as shown in FIG. 2B. Next, in step D, the placement of the components is corrected so that the wiring density becomes appropriate based on the wiring information indicated by the rat nest 2. Next, in step E, the wiring between the connection terminals of each component whose layout setting has been determined has been completed.

[0004]

However, in the conventional printed board CAD system, although the wiring density is predicted by the rat nest information to perform the wiring design, for example, as shown in FIG. Although the rat nest 4 connecting the terminals a of 1b and 1c and the rat nest 2 connecting the terminals b are different information, the rat nest 4 overlaps on the display and an accurate wiring density cannot be predicted. For this reason, in some areas, the allowable wiring density is often exceeded. There is a problem that a great number of man-hours are wasted even if the area where the wiring density exceeds is searched and corrected.

SUMMARY OF THE INVENTION An object of the present invention is to provide a printed board CAD system capable of accurately grasping the wiring density of each region and designing in a shorter time in order to solve such a problem.

[0006]

According to a first printed board CAD system of the present invention, at least the step of inputting the external dimensions of the printed board and the components to be arranged and the information of terminals to be connected, and based on these information. A step of arranging the parts on the printed board, a step of wiring for connecting the terminals to each other, a step of dividing the printed board into a plurality of areas, and a grid in the divided areas. A grid arranging step of arranging vertically and horizontally at a predetermined interval, a first counting step of counting the number of grids scattered in the divided area, and a number of grids included in the wiring in the divided area And a step of calculating the wiring density by dividing the number of grids in the second counting step by the number of grids in the first counting step. .

In addition to the first printed board CAD system, the second printed board CAD system includes a display step for displaying the calculated wiring density. Further, this display step is characterized in that the size of the wiring density is displayed by comparing the colors.

[0008]

The present invention will be described below with reference to the drawings.

1A and 1B are a partial plan view showing a flowchart and a part of the printed board for explaining an example of the printed board CAD system of the present invention. This printed board CAD system has a step of specifically determining the wiring density in addition to the conventional step of predicting the wiring density based on rat nest information. Furthermore, the wiring density can be displayed on the display so that the wiring density can be easily understood.

First, as shown in the conventional example, as shown in FIG.
While the wiring density is predicted from the rat nest information in steps A to D shown in (1), a temporary wiring wiring design is performed in step E. Next, in step F, the area on the printed board is divided into areas having different allowable wiring densities or, if the allowable wiring densities are the same, into areas of arbitrary size. Next, in step G, as shown in FIG. 1B, the grids 4 are arranged vertically and horizontally in each region of the printed board at intervals according to the allowable wiring density. Then in step H,
The number of grids 4 in one area is counted. For example, in FIG.
In (b), it is assumed that there are 36 on each side. Next, in step I, the number of lattices 4 in the wiring is counted. The number of grids is, for example, 18 on the component mounting surface and 18 on the back surface side. (The number of grids in the area including the periphery of the through hole 5 is also 8 added.) Next, in step J, the number of grids in the wiring is divided by the number of grids in the area to obtain the wiring density in this area. To calculate. That is, here, the total number of grids in the wiring, 34, is divided by 72, which is included in the front and back areas of the printed board, to obtain 34/72 = 0.
472, and a wiring density of about 47% is calculated. In this way, the wiring density is calculated for each of the divided areas, and when the wiring density of the entire area of the printed board is calculated in step K, the wiring density is displayed for each area on the display in step L. .

Here, when displaying the wiring density, for example, if the wiring density is a single color, the wiring density becomes clear.
It is advisable to increase the saturation in the region where the wiring density is high, and to divide the areas where the wiring density exceeds the allowable wiring density with another color such as red.
Further, as another example, it is possible to distinguish by colors having different lightness, and the point is to display the high and low of the wiring density by contrasting the colors.

As described above, since the wiring density can be framed for each area, the correction at the time of actual wiring can be made easier,
It has the advantage that it can be designed in a short time.

[0013]

As described above, according to the present invention, the steps of arranging the grids in a row and column at a predetermined interval for each area,
A printed board that can be designed in a shorter time without wasting man-hours by counting the number of scattered grids, calculating the area occupied by wiring in the area, and calculating and displaying the wiring density for each area There is an effect that a CAD system can be obtained.

[Brief description of drawings]

FIG. 1 is a partial plan view showing a flowchart and a part of a printed board for explaining an example of a printed board CAD system of the present invention.

FIG. 2 is a diagram illustrating a flowchart for explaining an example of a conventional printed board CAD system and a part of a printed board drawn on a display.

[Explanation of symbols]

 1a, 1b, 1c parts 2 rat nest 3 terminal 4 lattice 5 through hole

Claims (3)

[Claims] 1. A step of inputting at least information about a printed board and external dimensions of a part to be placed and terminals to be connected, a step of placing the part on the printed board based on the information, A wiring step of connecting the terminals to each other, a dividing step of dividing the printed board into a plurality of areas, and a grid arranging step of arranging grids vertically and horizontally at predetermined intervals in the divided areas are divided. A first counting step of counting the number of grids scattered in the area, a second counting step of counting the number of grids included in the wiring in the divided area, and a second counting step. And dividing the number of grids of the grid by the number of grids in the first counting step to calculate the wiring density. 2. The printed board CAD system according to claim 1, further comprising a display step of displaying a step of displaying the calculated wiring density. 3. The printed board CAD system according to claim 2, wherein the display step displays the magnitude of the wiring density by color comparison.