JPS629223B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to lead structures, particularly lead structures in high density integrated circuit packages.

The conventional lead structure uses multiple leads to connect multiple external connection pads arranged around the wiring board and multiple internal connection pads on the integrated circuit mounted on the wiring board. The terminal on the connection pad side has a flat plate structure,
The intervals between the plurality of external connection pads are wider than the intervals between the internal connection pads due to restrictions on the wiring pattern of the wiring board. However, as the degree of integration of integrated circuits increases, it becomes difficult to arrange external connection pads and leads in a limited area on a wiring board to accommodate the increase in internal connection pads of integrated circuits.
An increase in the area of the lead structure poses a problem. Furthermore, as the degree of integration increases, when meeting the demand for additional wiring without modifying an already manufactured wiring board, the conventional lead structure has the drawback that it is difficult to perform additional wiring.

A conventional example will be described below with reference to the drawings.
FIG. 1 is a plan view showing an example of a conventional lead structure, in which external connection pads are arranged in a row and leads are arranged in a plane. A plurality of external connection pads 4 arranged in a row on the wiring board 11 are connected to internal connection pads 2 on the integrated circuit due to the wiring pattern of the wiring board.
I can't make the distance as narrow as that. As shown in the figure, the lead structure in which the external connection pads 4 arranged in a row around the wiring board 11 and the internal connection pads 2 are connected in a plane by the leads 6 can only arrange a plurality of external connection pads 4 in one row. The inside of the row of external connection pads 4 cannot be used as a space for arranging another plurality of external connection pads, resulting in poor mounting efficiency.

FIGS. 2a and 2b are a side view and a cross-sectional view showing other examples of conventional lead structures, respectively, showing an example of an integrated circuit package in which connection pins corresponding to the leads shown in FIG. 1 are arranged in multiple layers. Insulator 1 as shown in the figure
By providing the first connecting pin 12 on the outside of the insulator and the second connecting pin 13 on the inside of the insulator, the planar arrangement of the leads can be made into a multilayer arrangement compared to the conventional example shown in FIG. Since it is possible to do so, it corrects the inefficient mounting of connection leads. But the first
The terminals of the connecting pin and the second connecting pin have a flat plate structure, and each has a drawback that it is difficult to add wiring because there is only one connecting surface. (Also, it is not a structure that can be applied to a multilayer wiring board where there are obvious restrictions on the height of the wiring board when mounting an integrated circuit package on the wiring board as shown in Figure 2.)
As is clear from the examples in Figures 1 and 2 a and b, the conventional lead structure has the disadvantage of poor mounting efficiency of external connection pads and leads as the density of integrated circuits increases, and additional wiring for modification etc. There is a drawback that it cannot be done.

The purpose of the present invention is to respond to the increasing density of integrated circuits,
The purpose of the present invention is to provide a lead structure that improves the mounting efficiency of external connection pads and leads and allows additional wiring for modification.

The lead structure of the present invention includes a plurality of first external connection pads formed in a row on a wiring board, and a plurality of first external connection pads formed in a row parallel to the row of the plurality of first external connection pads on the wiring board. A second external connection pad, a plurality of first internal connection pads formed around the integrated circuit mounted on the wiring board, and a plurality of first internal connection pads formed one each between adjacent first internal connection pads. a second internal connection pad, and a plurality of first leads connected to the corresponding first external connection pad through a columnar conductor provided at one end and connected to the first internal connection pad at the other end. , a plurality of ring-shaped conductors each having one end connected to the corresponding second external connection pad through a ring-shaped conductor having a shape through which the columnar conductor can penetrate, and the other end connected to the corresponding second internal connection pad. a second lead; and an insulating layer for insulating the plurality of first leads mounted on the wiring board and formed on the front surface and the plurality of second leads formed on the back surface. be done.

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIGS. 3a, 3b, and 3c are top views, sectional views, and partial perspective views showing an embodiment of the present invention, respectively, showing an embodiment in which external connection pads are arranged in multiple rows and leads are arranged in multiple layers. The top view of FIG. 3a shows that a plurality of first interconnect pads 2 are arranged around the periphery of the integrated circuit 1, and second interconnect pads 3 are arranged adjacently to said interconnect pads 2. The plurality of external connection pads include a plurality of external connection pads 4 formed in a row near the periphery of the wiring board 11, and a second external connection pad parallel to the row of external connection pads 4 and near the integrated circuit 1. Pads 5 are formed in a row.
A plurality of leads 6 connect between the plurality of internal connection pads 2 and the corresponding plurality of external connection pads 5; and a plurality of leads connect between the plurality of internal connection pads 3 and the plurality of corresponding external connection pads 4. 7 are arranged one above the other on the wiring board with an insulating layer 8 in between. FIG. 3b is a sectional view taken along the line AA' shown in FIG. 3a, and is intended to clearly show the relative positions of the leads 6, 7, and the insulating layer 8.

FIG. 3c is a perspective view showing the terminal structure of the leads 2 and 3 on the external connection pad side, and the insulating layer is omitted. The terminal of lead 2 is a columnar conductor 9
is added, and one end of the columnar conductor is connected to external connection pad 5.
By connecting to the columnar conductor 9 and using the other end of the columnar conductor 9, additional wiring is possible. lead 3
A ring-shaped conductor 10 is added to the terminal of the column-shaped conductor 9 to form a hollow structure to which the other end of the column-shaped conductor 9 can be connected. Furthermore, by connecting the ring-shaped conductor to the external connection pad 4 and using the other end, additional wiring is possible.

As is clear from a comparison between the embodiment shown in FIG. 3a and the conventional example shown in FIG. In particular, the mounting efficiency is improved by arranging multiple external connection pads in multiple rows. As is clear from a comparison between the embodiment shown in FIGS. 3b and 3c and the conventional example shown in FIGS. 2a and 2b, the lead structure of the present invention has a coaxial lead structure for the external connection terminal,
Compared to the conventional flat plate structure, the number of connection end faces has increased, making additional wiring possible.

The lead structure of the present invention has the effect of improving mounting efficiency by forming a plurality of first leads and a plurality of second leads in multiple layers with insulating layers in between, and by arranging a plurality of external connection pads in multiple rows. Furthermore, the lead structure of the present invention has the advantage that by forming the terminals of the first lead and the second lead into a coaxial type structure, the number of connection surfaces of the leads can be increased and additional wiring can be made possible.

[Brief explanation of the drawing]

Figure 1 is a top view showing a conventional example, Figure 2 a,
3b is a side view and A-A' cross-sectional view showing another example of the conventional technology, and FIGS. FIG. 1...Integrated circuit, 2, 3...Internal connection pad,
4, 5...External connection pad, 6,7...Lead,
8... Insulating layer, 9... Columnar conductor, 10... Ring-shaped conductor, 11... Wiring board, 12, 13... External connection pin, 14... Insulator.

Claims (1)

[Claims] 1 A plurality of first external connection pads formed in a row on a wiring board, and a plurality of second external connection pads formed in a row parallel to the row of the plurality of first external connection pads on the wiring board. and a plurality of first circuits formed around the integrated circuit mounted on the wiring board.
a plurality of second internal connection pads formed between each adjacent first internal connection pad, and a corresponding first external connection pad via a columnar conductor provided at one end. a plurality of first leads, the other end of which is connected to the first internal connection pad; a plurality of second leads connected to the external connection pads and whose other ends are connected to the corresponding second internal connection pads; and a plurality of first leads mounted on the wiring board and formed on the surface thereof. A lead structure comprising: an insulating layer for insulating from a plurality of second leads formed on a back surface.