JPS6230400A - Printed wiring board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a printed wiring board on which a substantially rectangular LSI package such as a flat package is mounted.

[Technical background of the invention and its problems] Generally, in a printed wiring board having two or more layers, a wiring pattern is laid using a pair of wiring layers. For example, 2 shown in FIG.
In the layered printed wiring board 10, main wiring patterns 11, 11,
... is arranged, and its I
Subordinate wiring patterns 42, 12, . . . are arranged in the vertical direction. Then, the main wiring pattern 11 and the sub wiring pattern 1
A via hole (through hole) 13 for connecting both patterns 11 and 12 is provided at the connection intersection of the two patterns.

This wiring pattern wiring method is extremely rational and can accommodate a large number of wiring lines per unit area. Therefore, the above method is also applied to automatic wiring algorithms using computers.

When various components are mounted on a printed wiring board, each component is arranged horizontally or vertically to the main wiring pattern. In the example of the printed wiring board 10, a flat package 2 shown in FIG.
0 is a lead 21 formed protrudingly on two opposite sides thereof.
．． One and the other of the rows of leads 22, 22, and so on protruding from the other two opposing sides are horizontal to the rows of main wiring patterns 1i, ii, and so on. ,! ! ! It is arranged so that it is facing directly. In this case, the leads 21, 21... of the flat package 20
(Lead connection part for connection) Lead connection pattern 1
4.14... are the main wiring patterns 11. The lead connection patterns 15.15... are the main wiring patterns 11. 11... are arranged in the direction perpendicular to the columns. Lead connection pattern 14.14.15.15・
. . . are directly or indirectly connected to necessary main wiring patterns among the main wiring patterns 11, 11, .

Now, the length of lead connection pattern 14.14... is
Since the arrangement direction thereof is horizontal to that of the main wiring patterns 11, 11..., the leads 21
, 21..., that is, lead 2
A length of about 1, 21, etc. is sufficient. On the other hand, the lead connection patterns 15, 15..., whose arrangement direction is orthogonal to that of the main wiring patterns 11, 11..., need to function as lead wires, so they are shown in Fig. 3. As shown, a considerable pattern length is required. In this case, lead connection patterns 15, 15,
The area occupied by ... increases, and the same pattern 15°15.
. . . There is an increase in wasteful free space near which wiring cannot be done.

That is, in the conventional printed wiring board 10, the presence of the lead connection pattern T5.15, which needs to function as a leader line, affects the peripheral area of the flat package 20, as well as the wiring accommodation rate and packaging density of the entire printed wiring board 10. There was a problem with the drop of 1G. This problem has become more common with the increasing integration of semiconductor devices.
The problem was more noticeable as the number of input/output bins of the I package increased.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to reduce the lead line portion occupied by the lead connection portion connecting the leads formed on the four sides of a substantially rectangular LSI package such as a flat package. It is an object of the present invention to provide a printed wiring board that can significantly reduce the amount of wiring and thereby improve the wiring rate and packaging density.

[Summary of the Invention] In the present invention, the LSI package has lead connecting portions for connecting lead rows formed on four sides of a substantially rectangular LSI package in both horizontal and vertical directions to the main wiring pattern row. By forming the lead wires so that they are inclined, the lead wire portion that occupies the lead connection portion is reduced.

[Embodiment of the Invention] An embodiment of the invention will be described below with reference to FIGS. 1 and 2. Note that Figures 1 and 2 are similar to Figure 3. This corresponds to FIG.

In the two-layer printed wiring board 30 shown in FIGS. 1 and 2, main wiring patterns 31, 31, etc. are arranged horizontally on the surface of one wiring layer, and the other wiring On the back surface of the layer, slave wiring patterns 32, 32, . . . are arranged in the vertical direction. Via holes (through holes) 33 are provided mainly at connection intersections between the main wiring pattern 31 and the sub-wiring pattern 32 to connect both patterns 3L 32.

On the surface of the printed wiring board 30, leads 41, 41, . A lead connection pattern 34° 34 (which is a lead connection part) for direct connection,
Lead connection patterns 35, 35, . . . for directly connecting leads 42, 42, .
1.31... in the horizontal (parallel) direction and in the direction perpendicular to the main wiring pattern 31.31... (i.e., the sub wiring pattern 3
2) with an inclination to either direction. Note that the flat package 40 is
For example, it is an LSI with 92 pins (36 pins in FIG. 2 due to drawing constraints).

Now, in this embodiment, lead connection pattern 34.
The inclinations of 34 with respect to the horizontal and vertical directions to the main wiring pattern 31 are both 45 degrees. Also, the inclinations of the lead connection patterns 35, 35, . Therefore, the inclination of the flat package 40 mounted on the printed wiring board 30 with respect to the main wiring patterns 31, 31, . . . is 45 degrees. Also, lead 1 concubinage pattern 34° 34, 35
．． 35... One end side is the main wiring pattern 31.31.
It is integrally connected to the necessary main wiring pattern among... with an inclination of 45 degrees. Lead connection pattern 34
．． 34.35.35...lead 41.41.42.
The connecting portions with 42 are formed to have a wide width so that they can be connected by, for example, soldering.

In the printed wiring board 30 described above, the lead connection pattern 34
．． 34.35.35... as main wiring pattern 31.31
... are arranged with an inclination to both the horizontal and vertical directions, so the same pattern 34.34.35.35.
. . , to a necessary main wiring pattern among the main wiring patterns 31, 31, . . . can be substantially minimized. Therefore, as is clear from the comparison with the conventional example shown in FIGS. 3 and 4, the printed wiring board 3
Lead connection pattern at 0 34.34.35°35
The occupied area of ... decreases, and the same pattern 34.34
There is no wasteful empty area that cannot be used for wiring in the vicinity of degrees 35, 35, . . . .

In the above embodiments, the case was explained in which it was applied to a printed wiring board on which a flat package is mounted. The same can be applied when mounting an LSI package. However, the bottle
The lead connection pattern (lead connection) applied to the grid array includes lands formed in via holes (through holes) for inserting bottles. Further, the inclination of an LSI package such as a flat package with respect to the main wiring pattern is not necessarily limited to 45 degrees.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to reduce the lead line portion occupied by the lead connection portion that connects the leads formed on the four sides of a substantially rectangular LSI package such as a flat package. Therefore, it is possible to reduce the area occupied by the lead connection portion and the vacant area where wiring is not possible, which tends to occur near the same pattern. Therefore, according to the present invention, it is possible to improve the wiring rate (reduce the unconnected rate) and further improve the packaging density.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a printed wiring board according to an embodiment of the present invention, FIG. 2 is a plan view showing a flat package mounted on the printed wiring board of FIG. 1, and FIGS. 3 and 4 are FIG. 2 is a plan view showing a conventional example. 3019. Printed wiring board, 31.31...Main wiring pattern, 32°32...Sub wiring pattern, 34.34.3
5.3515. Lead connection pattern (lead connection part),
40...Flat package, 41.41.42.4
2...Lead. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Claims] Lead connection portions for connecting lead rows formed on four sides of a substantially rectangular LSI package are arranged such that the LSI package is inclined with respect to both horizontal and vertical directions to the main wiring pattern row. A printed wiring board characterized by being formed as follows.