JPS632107B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention utilizes computer technology.
The present invention relates to a method for producing a photographic original plate for a printed circuit board, which employs a CAD method to produce a photographic original plate for a printed circuit board.

In this method, as shown in Fig. 1, an electrical circuit diagram is printed on inch mesh base paper P on which vertical lines 1 _V and horizontal lines 1 _H , each serving as a basic grid, are printed at intervals of 2.54 mm. The original design drawing is manually scaled to 2 scale as in the case of vertical artwork production.
Drawing at double is done first.

If the printed circuit board is for mounting an integrated circuit (IC), the spacing between the pins of the IC depends on the standard.
Since the diameter is determined to be 2.54 mm, the IC pin insertion hole 10 is drawn by setting its center at the intersections C ₁ and C ₂ of the basic grid, as shown in FIG. On the other hand, the printed wiring pattern 11 is drawn by setting its starting end and ending point at the intersections of a basic lattice (not shown), and by setting its bending points at the shown intersections C ₃ and C ₄ . A land 12 is formed around the pin insertion hole 10 and is used to electrically connect the pin of the IC to the wiring pattern using deep solder or the like. Although not shown in the figure, in addition to these, holes for inserting lead wires of discrete elements are also drawn on the intersections of the basic lattice in the original drawing.

In the CAD method, next, the original design drawing prepared as described above is attached to a digitizer plate _D1 of a digitizer D as shown in FIG. 3, and digitizing work is performed. Digitizing work is done by placing a cursor K (or probe) on the intersection points _C1 to _C4 , etc., which correspond to the bending points of the pin insertion hole 10 and wiring pattern 11, drawn on the original design drawing, and reading the positions of these intersection points. This is to read the information necessary for producing the original photographic plate from the original design drawing, and the information read in this process is stored in memory. This stored information is then read out and utilized by the photoplotter to render the photographic master.

As mentioned above, the CAD method uses a photo plotter to draw the original photo, and is therefore more suitable for creating photo originals for printed circuit boards that are more complex and have a higher packaging density than the method of creating original photo plates using artwork. It is becoming widely used.

By the way, the power consumption of recent ICs has become smaller, so even if the width of the wiring pattern is narrowed, the heat generated by Joule heat does not become large enough to become a problem. For this reason, in order to increase the degree of freedom in original design and further improve the mounting density of printed circuit boards, the width of the wiring patterns has been reduced and IC
There is an increasing demand for printed circuit boards in which two or more upper wiring patterns are passed through the gaps between the pins, that is, the pin gaps.

If we consider the original paper in Figure 1 again, in this original paper, the wiring pattern that can be read in the later digitizing process corresponds to the basic grid as well as the line drawn in the center between the basic grids. However, it can also be drawn on the half lattice 2 shown by broken lines, which is not actually printed. However, when attempting to create two wiring patterns in the pin gap using this half-lattice 2, the wiring pattern and the land 12 may come into contact with each other, or the diameter of the land or the width of the wiring pattern may become extremely small. Therefore, the base paper shown in FIG. 1 cannot be applied to the production of a photographic original plate for a printed circuit board that meets the above-mentioned requirements.

For this reason, as shown in Fig. 4, vertical lines 1 _V ' and horizontal lines 1 _H ', which form the basic grid with an interval b of 5.08 mm, and auxiliary grids 2', which divide the basic grid into five equal parts, are printed on the paper. It was considered to use the mesh base paper P' prepared in this manner to pass two wiring patterns 11 through the pin gaps, as shown in FIG.

However, the base paper shown in FIG. 4 is completely different from the generally used inch mesh base paper shown in FIG. 1, and it is expensive because it must be made according to special specifications. Also, since there is no grid in the center of the pin gap, if you try to pass one wiring pattern through the pin gap, the pattern will be biased toward one land, which will cause an imbalance, and for the same reason. However, there is a problem in that three wiring patterns cannot be passed through the pin gaps.

This problem seems to be solved by forming an auxiliary grid that divides the pin gap into 10 equal parts, but
When dividing into 10 equal parts, the gap between the grids becomes extremely small at 0.508mm on the base paper, which not only makes it difficult to create a design original at twice the scale, but also causes errors in reading during digitizing work, which is another problem. begins to occur. Of course, this problem would not occur if the drawings were drawn at four times the scale, but the original design drawings would become too large and difficult to handle.

The present invention has been made in view of the above points, and
The purpose of this is to draw one to three printed wiring lines between the pin gaps of the IC based on a design drawing drawn at double scale on a standard sheet of standard inch mesh paper, which has not been changed to a large width. It is an object of the present invention to provide a method for producing a photographic original plate for a printed circuit board, which can produce a photographic original plate for a printed circuit board through a pattern by a CAD method.

Embodiments of the present invention will be described below with reference to FIGS. 6 to 10 a and b.

Figure 6 shows inch mesh base paper P'' used in the method of the present invention, with cross marks 3 placed at the centers of the squares formed by vertical lines _1V and horizontal lines _1H , which form the basic grid. 1 except that
It is the same as the base paper P shown in the figure. Therefore, in order to make the base paper P'' in Figure 6, the printed base paper P'' in Figure 1 must be
Since it is only necessary to additionally print cross mark 3, base paper P'' does not become expensive.Also, if cross mark 3 is ignored, it can be used in the same way as base paper P in Figure 1. can.

For the base paper P'' in Figure 6, as shown in Figure 7,
Radius inscribed in cross mark 3 and basic grid
By drawing a 0.635 mm circle 20 centered at the intersection of the cross cursor line k of the cursor K of the digitizer D (Figure 3), it is possible to draw a circle 20 of 0.635 mm with the intersection of the cross cursor line k of the cursor K of the digitizer D (Fig. It becomes possible to identify up to Therefore, if we draw a double-scale original design using the original paper P'' in Figure 6, we will create an auxiliary grid 2 with an interval C of 0.635 mm that divides the gap between the IC pins into eight equal parts, as shown in Figure 8. The same effect can be obtained as if `` is provided.

If you draw an original drawing with one wiring pattern passing through the pin gap using the base paper P'' in Figure 6, you will get exactly the same thing as in Figure 2. Then, two wiring patterns 11 will be drawn between the pin gaps. When passing, as shown in FIG. 8, the original drawing can be drawn using two wires on both sides of the auxiliary grid 2'' located at the center between the pins. However, in this case, the diameter d of the land 12 and the width e of the wiring pattern 11
are 1.2 to 1.3 mm and 0.2 to 0.25 mm, respectively, because if they are the same as in the case of one piece, the land 12 and the pattern 11 and the patterns 11 will be too close to each other.
selected.

Next, when passing three wiring patterns 11 through the pin gaps, as shown in FIG. Yes, Randall 12 in this case.
The diameter d of the pattern 11 and the width e of the pattern 11 are selected to be 1.2 mm and 0.15 mm, respectively.

If the printed circuit board is double-sided printed, there should be two holes in the gap on the IC mounting surface, that is, the IC mounting surface.
If three wiring patterns 11 are passed through, it is possible to form a land 12 with a large diameter on the solder depth side, as shown by broken lines in FIGS.
There is no lack of IC mounting strength.

As described above, according to the method for producing a photographic original plate for a printed circuit board of the present invention, a cross mark is attached to the center of each square of inch mesh base paper to create an auxiliary grid that divides the gap between the IC pins into eight equal parts. The scale uses the central three of the auxiliary grids in the pin gap to draw a printed wiring pattern that passes through the pin gap, making it possible to pass one or two wiring patterns through the pin gap. In addition to making it possible to pass three wiring patterns through the pin gaps using the same base paper, which was previously considered impossible, and at twice the scale, it also eliminates the need for major changes to the mesh base paper, making it an inexpensive base paper. Many useful effects can be obtained, such as the use of .

[Brief explanation of the drawing]

Figure 1 is a diagram showing a general inch mesh base paper, Figure 2 is a diagram showing an example of a design original created using the base paper in Figure 1, and Figure 3 is a perspective view showing an outline of a digitizer. Figure 4 shows a modified example of a conventional mesh base paper, Figure 5 shows an example of an original diagram drawn using the base paper of Figure 4, and Figure 6 shows an inch mesh used in the method of the present invention. Diagram showing the original paper,
Figure 7 is a diagram for explaining how to use the base paper in Figure 6, Figures 8 and 9 are diagrams showing examples of original design drawings drawn using the base paper in Figure 6, and Figure 10a. 3 and b are plan views respectively showing examples of double-sided printed circuit boards made from photographic original plates made by the method of the present invention. P′...inch mesh base paper, 1 _V ...vertical line,
1 _H ...Horizontal line, 2''...Auxiliary grid, 3...Cross mark, 10...Pin insertion hole, 11...Printed wiring pattern.

Claims (1)

[Claims] In a method for producing a photographic original of a printed circuit board for integrated circuit tower using a CAD method based on an original design drawing drawn at double scale on a 1-inch mesh base paper,
A cross mark is attached to the center of each square of the inch mesh base paper to form an auxiliary grid that divides the gap between the pins of the integrated circuit into eight equal parts, and three central grids of the auxiliary grid in the gap are formed. A method for producing a photographic original plate for a printed circuit board, characterized in that a printed wiring pattern passing through the gap is drawn using the following method.