JPS5927539A - Pad arranging method for ic chip - Google Patents

Abstract

PURPOSE:To readily mount an electronic device such as a thermal head or the like on an IC chip by continuously arranging driving and outputting pads along one side of the chip. CONSTITUTION:Driving and outputting pads O1-O32 are arranged in one row continuously along the up side of the surface of an IC chip 6, three ground pads GND1-GND3 are arranged along the left side, and three ground pads GND4- GND6 are arranged along the right side. The emitters of 32 output transistors are all connected to a common ground line in the IC chip, three pads are led out along the left side of the chip 6 from the common ground line, and three pads are led out along the right side from the common ground line, and the yield of bonding to the ground pads can be largely improved by employing the common ground.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an IC (S
This invention relates to a method for arranging pads on chips (integrated circuits such as SI, MSI, LSI, etc.).

Some thermal heads have IC chips as drive circuits arranged along heat generating resistors arranged along the longitudinal direction. As an example of the circuit configuration of one such IC chip, as shown in FIG.
A shift register 1 inputs data from a data input terminal DATAIN and increments it at the timing of a clock signal from LOCK・, and a latch circuit 2 that inputs a signal from the shift register 1 according to a load signal from a load terminal LOAD and holds it. , an output transistor 3 that drives and heats a heating resistor (not shown) based on a signal held in the latch circuit 2, and a gate that controls the timing at which the output transistor 3 operates based on a strobe signal from a strobe terminal 5TROBE. There is one with 4.

This IC drives 32 heating resistors per chip, the shift register 1 and latch circuit 2 both have a capacity of 32 bits, and 32 output transistors 3 and 32 gates 4 are provided each. There are also 32 drive output pads (0□ to 032) connected to the collector of the output transistor 3 and connected to the heating resistor.

Note that the terminal CLEAR is a terminal for clearing the shift register 1, and the terminals vDD and ■ss are power supply terminals and ground terminals for driving the shift register 1 and the latch circuit 2 themselves. A necessary number of such Ic chips are provided depending on the number of heating resistors.

By the way, in the circuit diagram of Fig. 1, the emitters of the output transistors 3 connected to the ground terminal GND are all connected to a common ground line, but in terms of implementation, the emitters of the output transistors 3 are connected to the common ground line. One ground pad is taken out in the same direction as the drive output pads 01 to 032. Therefore, the pad arrangement of the IC chip is such that, as shown in FIG. 6 is arranged and tailed. -I 1~Is HaD, AT A I
N, CLl Pad for OCK and other input/output signal terminals.

However, in the thermal head, the heating resistors are arranged continuously in one direction, whereas in the above IC chip, as shown in FIG.
and ground pads GND1 to GND, 6 are 2:1
However, since the IC chips 5 are arranged alternately, for example, when mounting such IC chips 5 on a thermal head using the 5i tape carrier method, the drive output pad and the ground pad are arranged on the tape carrier. Therefore, the drive output pads 01 to 032 and the ground pad GN must be connected to the leads facing in opposite directions.
The pad array consisting of D-GND16 is bonded (
inner lead bonding) is not possible. Therefore, it is necessary to use a tape carrier in which lead patterns are formed on both sides of the tape base material, or to use two ordinary tape carriers. Such a mounting method is disadvantageous in terms of the thermal head 9 assembly process, yield, and cost.

Such problems are limited to thermal heads, displays, sensor arrays, etc. where a large number of display elements and detection elements are arranged, and the I/O as a drive circuit is arranged along the arrangement.
This is a common problem in devices that arrange and mount c-chips.

In view of the above problems, it is an object of the present invention to provide a pad arrangement method that makes it easy to mount an IC chip on an electronic device such as a thermal head. The purpose is to achieve the above object by arranging them continuously along the . Therefore, the ground pads are arranged at a different location from the arrangement of the drive output pads.

An example will be described below.

FIG. 3 is a pad layout diagram of an example in which the present invention is implemented in an IC chip having the circuit configuration shown in FIG. The drive output pads 0□ to 032 are arranged in a continuous line along the upper side of the surface of the IC chip 6, and three ground pads (GND-GND3) are arranged along the left side, and three ground pads (GND-GND3) are arranged along the right side. Three pieces (GND - GND6) are arranged along the line. The input/output credit card I"", 1g is the same as in FIG.

In this embodiment, the output transistor 3 is similar to the conventional example shown in FIG.
Instead of connecting two emitters of each output transistor 3 to a common ground pad, the emitters of the 32 output transistors 3 are all connected to a common ground line within the IC chip, and the emitters of the 32 output transistors 3 are connected to a common ground line from the common ground line to the Three pads (GNI) 1 to GND 3) are taken out along the left side, and three pads (GND - GNI) 6) are taken out along the right side. In this way, by making the ground common, the yield of bonding to the ground pad is greatly improved.

As described above, according to the present invention, the drive output pad is Ic
Since they are arranged continuously along one side of the chip surface, when mounting such an IC chip on a thermal head or other electronic equipment, for example, when using the tape carrier method, the leads are placed on only one side of the tape base material. Bonding can be carried out using a single ordinary tape carrier on which a pattern is formed, thus achieving the effect of providing an easy-to-mount IC chip.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an example of the circuit configuration of one IC chip used in a thermal head drive circuit, Fig. 2 is a schematic plan view showing the pad arrangement of a conventional IC chip incorporating the circuit shown in Fig. 1; FIG. 3 is a schematic plan view showing the pad arrangement of an IC chip incorporating the circuit shown in FIG. 1 and to which an embodiment of the present invention is applied. 6... Ic chip, 01-032... Drive output pad, GND -GND6... Ground pad. Patent applicant Ricoh Co., Ltd.

Claims (1)

[Claims] (1) A pad arrangement method for an IC chip, which comprises arranging drive output pads continuously along one side of the IC chip.