JPH04214695A - Semiconductor device - Google Patents

Abstract

PURPOSE:To enhance mounting density of a semiconductor device to be mounted at the surface of a printed circuit board. CONSTITUTION:Pins 12 to 14 for chip select signal are provided at the area of semiconductor device 11 where a pin 2 for signal is not provided. These chip select signal pins 12 to 14 are connected with an operation selection circuit of a semiconductor chip. In this case, the semiconductor device 11 is stacked for the mounting in the plural number on the same area of a printed circuit board 3. Since only the semiconductor device 11 in which a signal is applied to the chip select pins operates, if the semiconductor devices are stacked for the mounting in three dimensions, the other semiconductor devices 11 do not operate irregularly.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device surface-mounted on a printed circuit board.

0002

2. Description of the Related Art Conventionally, some surface-mounted semiconductor devices have a plurality of external connection leads protruding from the side of a resin package, each having a terminal end connection portion distributed downwardly. A conventional semiconductor device of this type will be explained with reference to FIGS. 3 and 4.

FIG. 3 is a side view showing a conventional semiconductor device surface-mounted on a printed circuit board, and FIG. 4 is a plan view showing a conventional semiconductor device surface-mounted on a printed circuit board. In these figures, reference numeral 1 denotes a mold resin serving as a resin package, and a semiconductor chip (not shown) is sealed within this mold resin 1. Reference numeral 2 denotes a conventionally known signal pin as an external connection lead connected to the semiconductor chip in the molded resin 1 to electrically connect the semiconductor chip and external wiring. A plurality of signal pins 2 are provided on two sides of the molded resin 1, each protruding laterally, and each of the signal pins 2 is provided with a molded resin 1 at the protruding end.
Soldering portions 2a are formed ubiquitously on the lower surface side.

3 is a printed circuit board, and this printed circuit board 3
A soldering pad (not shown) to which the signal pin 2 is soldered is formed on the top. Note that this soldering pad is connected to a wiring pattern (not shown) that constitutes a circuit on the printed circuit board.

The conventional semiconductor device constructed as described above is surface mounted by placing the mold resin 1 on the printed circuit board 3. At that time, the soldering portion 2a of the signal pin 2 is soldered to the soldering pad on the printed circuit board 3. As shown in FIG. 4, a plurality of conventional semiconductor devices are mounted on one printed circuit board 3 in a two-dimensional array.

[0006]

However, if the semiconductor devices are arranged and mounted on a printed circuit board in this way, there is a limit to how many semiconductor devices can be mounted on one printed circuit board 3. That is, in conventional semiconductor devices, it is not possible to further increase the packaging density.

[0007]

[Means for Solving the Problems] A semiconductor device according to the present invention connects a printed circuit board and an operation selection circuit of a semiconductor chip to a side portion of a resin package where no leads are provided, and uses an external signal to A chip selection lead is provided to selectively operate the chip, and the protrusion dimension of the external connection lead, the length of the chip selection lead in the vertical direction, and the arrangement position of the chip selection lead are adjusted vertically. The external connection leads of the upper and lower semiconductor devices are connected to the same pad on the printed circuit board, and a plurality of semiconductor devices are stacked one above the other and mounted on the printed circuit board.

[0008]

[Operation] Since only the semiconductor device to which a signal is sent to the chip selection lead operates, a plurality of semiconductor devices can be stacked and mounted on a printed circuit board, and the area occupied by the semiconductor devices on the printed circuit board is reduced.

[0009]

Embodiment An embodiment of the present invention will be explained in detail below with reference to FIGS. 1 and 2.

FIG. 1 is a side view showing a semiconductor device according to the present invention surface-mounted on a printed circuit board, and FIG. 2 is a plan view showing a semiconductor device according to the present invention surface-mounted on a printed circuit board. It is. In these figures, the above figure 3
Components that are the same or equivalent to those explained in FIG. In these figures, reference numeral 11 denotes a semiconductor device according to the present invention, and a plurality of semiconductor devices 11 (three in this embodiment) are mounted on the same position on the printed circuit board 3 so as to be stacked. The signal pins 2 of each semiconductor device 11 are soldered to the same position on the printed circuit board 3 when viewed from above, as shown in FIG. The dimensions are set according to the vertical position of the device 11.

Reference numerals 12, 13, and 14 are chip select signal pins as chip selection leads, and these chip select signal pins 12 to 14 are provided protrudingly in a portion of the molded resin 1 where the signal pin 2 is not provided. has been done. In addition, each chip select signal pin 12, 13, 14
One end is connected to the operation selection circuit of the semiconductor chip, and the other end (the end protruding from the molding resin 1) is placed below the molding resin 1 and soldered to the chip selection circuit (not shown) of the printed circuit board 3. Connected by attachment. Furthermore, these chip select signal pins 12, 13, 1
4 are disposed at different positions in the upper and lower semiconductor devices 11 when viewed from above, and their lengths in the vertical direction are set to dimensions corresponding to the vertical positions of the semiconductor devices 11. That is, the chip select signal pin 12 of the semiconductor device 11 located at the bottom is the shortest, and the chip select signal pin 14 of the semiconductor device 11 located at the top is the longest.

The semiconductor device 11 according to the present invention configured as described above has a plurality of signal pins 2 and chip select signal pins 12 to 14 soldered to predetermined positions on the printed circuit board 3. Implemented one after the other. For example, to operate the semiconductor device 11 located at the bottom, a chip select signal is sent to the chip select signal pin 12 of the semiconductor device 11 to operate the operation selection circuit of the semiconductor chip. The chip select signal is transmitted from an external circuit to the chip select signal pin 12 via the chip select circuit of the printed circuit board 3. That is, as shown in this embodiment, the semiconductor chip 1
Even if three semiconductor devices 1 are stacked and mounted on the same location on the printed circuit board 3, by selectively sending a chip select signal to the chip select signal pins 12 to 14 of each of the three semiconductor devices 11, any one of the semiconductor devices 11 can be mounted. One semiconductor device 11 can be selected and operated.

Therefore, since only the semiconductor device 11 to which a signal is sent to the chip select signal pin operates, it is possible to stack a plurality of semiconductor devices 11 and mount them on the printed circuit board 3. occupies a smaller area.

[0014]

Effects of the Invention As explained above, the semiconductor device according to the present invention connects the printed circuit board and the operation selection circuit of the semiconductor chip to the side portion of the resin package where no leads are provided, and connects the operation selection circuit of the semiconductor chip to the side portion of the resin package. A chip selection lead for selectively operating a semiconductor chip is provided in a protruding manner, and the protrusion dimension of the external connection lead, the vertical length of the chip selection lead, and the arrangement position of the chip selection lead are determined. The external connection leads of the upper and lower semiconductor devices are connected to the same pad on the printed circuit board, and multiple semiconductor devices are stacked one above the other and mounted on the printed circuit board, so the signal is sent to the chip selection lead. Since only the semiconductor devices that are sent operate, a plurality of semiconductor devices can be stacked and mounted three-dimensionally on a printed circuit board. Therefore, since the area occupied by the semiconductor device on the printed circuit board is reduced, the packaging density can be increased.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a state in which a semiconductor device according to the present invention is surface-mounted on a printed circuit board.

FIG. 2 is a plan view showing a semiconductor device according to the present invention surface-mounted on a printed circuit board.

FIG. 3 is a side view showing a conventional semiconductor device surface-mounted on a printed circuit board.

FIG. 4 is a plan view showing a conventional semiconductor device surface-mounted on a printed circuit board.

[Explanation of symbols]

1 Mold resin 2 Signal pin 3 Printed circuit board 11 Semiconductor device

Claims (1)

[Claims] 1. In a semiconductor device surface-mounted on a printed circuit board, in which a plurality of external connection leads having tip connection portions distributed downwardly are protruded from the side of a resin package, the semiconductor device is surface-mounted on a printed circuit board. A chip selection lead for connecting the printed circuit board and the operation selection circuit of the semiconductor chip and selectively operating the semiconductor chip by an external signal is provided protrudingly in a portion where the lead is not provided, and the external The protruding dimensions of the connection leads, the vertical length of the chip selection leads, and the arrangement position of the chip selection leads are changed depending on the vertical position, and the external connection leads between the upper and lower semiconductor devices are connected to the printed circuit board. A semiconductor device characterized in that a plurality of semiconductor devices are connected to the same pad and mounted on a printed circuit board in a stacked manner.