JPS6322351B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to automatic design of a connection pattern for a printed circuit board on which a plurality of integrated circuits are mounted. In particular, the present invention relates to a printed circuit board design apparatus that can perform high-density wiring.

[Conventional technology]

It is equipped with a key input device, a CRT image display device, and a photoprinter, a central processing unit that is connected to each of these devices and controls them, and a storage device connected to this central processing device. The processing device calculates the connection pattern on the printed circuit board according to the connection information on the printed circuit board given from the key input device, displays the figure of the calculation result on the above-mentioned CRT image display device, and also displays it on the above-mentioned photo plotter. A printed circuit board design apparatus configured to output as a photomask is known. With this device, it is possible to design complex wiring connection patterns containing a large number of integrated circuits at high speed and efficiently.

In such devices, information such as information about the shape of the printed circuit board to be designed and connection information giving the coordinates of two pins to be connected on the printed circuit board are input from a key input device (keyboard device or input tablet device). , and is configured to automatically search for possible and reasonable wiring paths between them.
As methods for automatically searching for this wiring route, the following methods have been known: 1. line segment search method 2. pattern method 3. maze method.

[Problem that the invention seeks to solve]

The line segment search method is the simplest method. When two points to be connected are given, line segments are searched alternately horizontally or vertically on the coordinates from one point to the other. This will be extended.
Although this method requires a short search time, the resulting connection patterns are limited to simple ones, and high-density wiring cannot be achieved.

In the pattern method, several connection patterns are prepared in advance and this pattern is selected and applied between two pin coordinates. Even if this could be done, it is not appropriate to design the whole thing this way. That is, to design the entire design using only this method, it is necessary to prepare and store an extremely large number of patterns, and the processing time for selection becomes long, making it impractical.

The maze method involves a large number of trials and errors to find a maze between two given points. Although this method allows for high-density wiring, it generally requires an extremely large number of trials and errors. This has the disadvantage of increasing the number of searches, which increases the amount of time it takes to search.

The present invention was developed against this background, and enables high-density wiring, shortens the processing time for the necessary search, and requires only a small number of patterns to be prepared and stored in advance. The purpose is to provide a printed circuit board design method.

[Means for solving problems]

The present invention provides for a rectangular segment in a storage device that includes n horizontally and m vertically (n and m are each integers of 3 or more) squares with minimum wiring spacing. In order to interconnect two squares for each set of squares, a large number of segment patterns with different shapes formed by connecting adjacent squares are accumulated for a large number of sets of two squares. , the central processing unit includes a means for defining a mesh divided into vertical and horizontal lattice shapes with the minimum wiring spacing over the wiring possible area on the surface according to input surface shape information of the printed circuit board to be designed; The present invention is characterized by comprising means for sequentially selecting applicable patterns from among the segment patterns according to the information and applying them to the surface defined by the mesh so that parts thereof overlap with each other.

One preferred method is to set the minimum wiring spacing to one third of the spacing between two adjacent pins of the integrated circuit mounted on the printed circuit board, and to set the segment size to n=4 and m=5. Another preferred example is to set the minimum wiring spacing to half the spacing between two pins, and set the segment size to 1=3 and m=3.

Here, the rectangle includes a square.

〔Example〕

Next, examples will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention. This device includes a CRT image display device 1,
A keyboard device 2 and an input tablet device 3 are provided at the operating position and are connected to an input/output interface 4. Furthermore, this apparatus includes a central processing unit 5, a storage device 6 connected to the central processing unit 5, and a photoplotter 7. The central processing unit 5 has a built-in microprocessor and controls each device connected to the input/output interface 4. The photoplotter 7 is connected to the central processing unit 5 via the input/output interface 4, and outputs the calculation results of the central processing unit 5 as photographic graphic information for the photomask.

In the device configured in this manner, connection information necessary to connect mutually among the many pins or terminals of integrated circuits and other components arranged on the printed circuit board is transmitted to the keyboard device 2 and the input tablet device 3. Enter from. The central processing unit 5 performs arithmetic processing on this to determine the connection pattern on the printed circuit board, displays this result on the CRT image display device 1, and outputs the result to the photoplotter 7 as photographic graphic information for the photomask. .

To explain the characteristic operation of the present invention, first, the surface of a printed circuit board for which a connection pattern is to be designed is expressed as a mesh divided into a vertical and horizontal lattice shape with a minimum wiring interval over a wiring possible area. This situation is shown in FIG. In other words, the minimum wiring spacing should be set so that one grid of the mesh, which is a square with four sides formed by this minimum wiring spacing, is provided between two pins of adjacent integrated circuits in this example. Set it to one third of the distance between the two pins. More specifically, since the standard integrated circuit pin spacing is 2.54 mm, the width of one mesh square is 0.847 mm. One wiring conductor is formed within this width so as not to come into contact with the adjacent wiring conductor.
Also, each square is represented by XY coordinates, with an arbitrary one of the squares of the mesh on this printed circuit board as a base point (X=0, Y=0).

Input information from a key input device can also be specified using these XY coordinates.

Here, it is possible to form connection patterns on both the front and back sides of the printed circuit board that is currently being designed, and the connection pattern on the front side is long in the horizontal direction, as shown by the diagonal line downward to the left in Figure 2. The principle is that the connection pattern on the back side is formed to be long in the vertical direction as shown by the diagonal line downward to the right in FIG. By establishing this principle, intersections of connection patterns can be easily separated into front and back sides, and
The soldering process becomes advantageous in the printed circuit board manufacturing process.

Next, divide one square of this mesh into n pieces horizontally and m pieces vertically (m and n are each integers of 3 or more).
Focus on the containing rectangular segment. The example shown here is n=4, m=5. Among these rectangular segments, several segment patterns as illustrated in FIG. 3 are prepared in advance. The starting point of each segment pattern is the position indicated by the triangle mark in FIG. The example shown in FIG. 3 is a part of the segment patterns that are prepared, and many other segment patterns are also prepared in advance.

Now in Figure 2, from one pin position P ₁ to another 1
Considering the case where wiring is to be performed to pin positions P _o as connection information, first point P ₁
Select a segment pattern based on . First, select connection pattern C in FIG. As a result, the wiring is extended as shown by the x mark in FIG. Next, a segment pattern is selected again starting from point _P2 . Here again, connection pattern C is selected and the wiring is further extended. In this way, the wiring is extended one after another while selecting a pattern so that the [4×5] size segments are partially overlapped, until reaching the position P _o .

The positions indicated by circles in FIG. 2 are positions designated in advance as positions where through holes can be formed. As a general rule, select the point where the direction changes from the horizontal connection pattern to the vertical connection pattern to be at the position marked with this circle, and the wiring will transition to the back side through the through hole at this position. When changing the orientation from a vertical connection pattern to a horizontal connection pattern, in principle, select the position marked with a circle, provide a through hole at this position, and transfer the wiring from the back side to the front side. In this example, it is allowed to proceed diagonally by one frame on the same plane, and, for example, connection patterns B to E shown in FIG. 3 are allowed.

As segment patterns to be prepared in advance, all conceivable segment patterns may be prepared, or some of them may be omitted to create a specific prohibition condition. Even when preparing all possible segment patterns, the size of the segments is very limited, such as [4 x 5], so the number of connection patterns for the entire printed circuit board must be varied. Compared to the conventional method, the number of devices that need to be prepared is significantly smaller.

An example of a flowchart for such an operation is shown in FIG.

In the above example, the rectangular segment is [4×5]
However, when one square of the mesh is placed between the pins of the integrated circuit, the appropriate size of this segment is [3×3]. Further, the size of this segment can be arbitrarily set depending on the size and purpose of the printed circuit board.

〔Effect of the invention〕

By setting a small rectangular segment like this and extending the wiring while selecting segment patterns prepared within this segment so that some of them overlap, the number of trial and errors can be significantly reduced and calculations can be made. It can be done in a short time. Also,
Compared to the conventional patterning method, the number of patterns to be prepared in advance is significantly reduced, and the capacity of the storage device for this purpose becomes practical when a microprocessor is used. Therefore, the degree of freedom of applicable patterns can be increased, such as including patterns that proceed in diagonal directions as connection patterns.
This makes it easy to select a wiring route and enables high-density wiring. Furthermore, if the possible positions of the through-hole are predetermined, the number of possible positions of the through-hole within one segment is limited, and the number of trial-and-error steps for setting the through-hole is significantly reduced. do.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing the mesh on the printed circuit board to be designed. FIG. 3 is a diagram illustrating connection patterns to be prepared. FIG. 4 is a diagram showing an example of an operation flowchart.

Claims (1)

[Scope of Claims] 1. A key input device, a CRT image display device, a photoplotter, and a central processing unit that is coupled to and controls the key input device, the CRT image display device, and the photoplotter, respectively. and a storage device connected to the central processing unit, the central processing unit comprising means for calculating a connection pattern on the printed circuit board according to connection information on the printed circuit board given from the key input device. and means for recording a figure resulting from the calculation of the means in the storage device, displaying it on the CRT image display device, and outputting it as a photomask to the photoplotter, wherein the storage device , there are n grids with minimum wiring spacing horizontally and m grids vertically (n and m are each 3
Segment patterns with different shapes are formed by connecting squares that touch each other in order to connect the two squares to each other for each set of two squares in a rectangular segment containing (an integer greater than or equal to) A large number of data are accumulated for a plurality of sets of the two squares, and the central processing unit calculates the minimum wiring spacing over the wiring possible area of the printed circuit board according to the input surface shape information of the printed circuit board to be designed. A means for defining a mesh divided into vertical and horizontal grids, and a means for sequentially selecting applicable patterns from among the segment patterns according to the connection information and applying them to the defined surface so that parts of the mesh overlap each other. 1. A printed circuit board design device characterized by comprising: a means for designing; 2 The minimum wiring spacing is one third of the spacing between two adjacent pins of an integrated circuit mounted on a printed circuit board.
The printed circuit board design apparatus according to claim 1, wherein n=4 and m=5. 3 The minimum wiring spacing is one half of the spacing between two adjacent pins of an integrated circuit mounted on a printed circuit board.
The printed circuit board design apparatus according to claim 1, wherein n=3 and m=3.