JPH04249332A - Inner-lead bonding method - Google Patents

Abstract

PURPOSE:To obtain a method by which an inner lead can be connected with high reliability without exerting an excess stress on a connecting part by a method wherein the tip part of the inner lead is bent so as to be brought close to the side of a bump-shaped electrode and the tip part which has been heated is brought into contact with the bump-shaped electrode by means of an elastically repulsive force which turns up and bends the tip part. CONSTITUTION:A plurality of bump-shaped electrodes 2 formed along the periphery of a semiconductor chip 1 in which an integrated circuit has been formed on one main face are connected to tip parts of inner leads 3 formed on a tape 5 so as to correspond to the bump-shaped electrodes 2. Such an inner-lead bonding method includes the following: a process by which the inner leads 3 are bent in advance in such a way that the tip parts of the inner leads 3 are brought close to the side of the bump-shaped electrodes 2; and a process by which the tip parts of the inner-leads 3 heated after the process are brought into contact with the bump-shaped electrodes 2 by using an elastically repulsive force which turns up the tip parts and by which the bump-shaped electrodes 2 are connected by melting a solder.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to TAB (Tape.
automated. The present invention relates to an inner lead bonding method for connecting bump-shaped electrodes of a semiconductor chip and inner leads formed in a tape shape in a bonding method.

0002

[Background Art] In recent years, as electronic notebooks, calculators, watches, and word processors have become smaller, more multifunctional, and less expensive, the semiconductor integrated circuit devices used in these devices have become thinner and smaller. At the same time, it is desired to reduce assembly costs. For such a semiconductor integrated circuit device, an assembly method called the TAB method is an assembly method that can realize a thin and inexpensive semiconductor integrated circuit device. In this method, a hole into which a semiconductor chip is inserted is formed in a strip-shaped resin sheet, and inner leads are formed around this hole to connect electrodes, which are the input/output terminals of the semiconductor chip. It is assembled using a sprocket hole that has the same holes as the sprocket holes for frame feed. Further, this method has the advantage of being easy to automate, and furthermore, since connection, mounting, and inspection can be performed continuously, assembly costs can be reduced.

[0003] Furthermore, a technical problem with this TAB method is the connection between the inner lead and the electrode. Normally, this connection is made by forming a spherical protrusion on the electrode with solder to form a bump-shaped electrode, and then pressing the tip of the inner lead onto the bump-shaped electrode and bonding it by thermocompression. In order to obtain high reliability and good weldability of this connection, improvements have been made in two aspects: the bump forming method and the inner lead bonding method, which is a bonding method.

FIGS. 4(a) and 4(b) are partial cross-sectional views of a semiconductor chip and a bonding apparatus shown in the order of steps to explain an example of a conventional inner lead bonding method, and FIG. FIG. Conventionally, in this inner lead bonding method, first, as shown in Figure (a),
A semiconductor chip 1 is mounted on a stage 7 placed on a carriage 8. Next, a tape 5 to which inner leads 3 are bonded with adhesive 4 is fed around the hole by a sprocket (not shown), and the hole is connected to the semiconductor chip 1 and the bump 2 whose tip end of the inner lead 3 is an electrode. positioned to match the top. Next, the inner lead 3 heated by the heater chip 6 is pressed against the bump 2 by the heater chip 6, and is soldered to the bump 2. In this connection step, as shown in FIG. 5, the next inner lead forming step is performed so that the inner leads 3 do not come into contact with the semiconductor chip 1.

In this step, as shown in FIG. 4(b), the semiconductor chip 1 attached to the tape 5 via the inner leads 3 is sent onto the next stage, that is, the die 9, by a sprocket (not shown). . The semiconductor chip 1 sent onto the die 9 is pressed with a rubber punch 10,
It is inserted into the recess of die 9. On the one hand, the part of the punch 10 that presses the inner lead 3 is rounded, and on the other hand, the die 9
Since the periphery of the recess is formed on an inclined surface, the portion of the inner lead 3 protruding from the semiconductor chip 1 is bent along the inclined surface and is shaped so as to maintain a sufficient distance from the semiconductor chip 1.

[0006]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional inner lead bonding method, the force with which the heater chip presses the inner lead is biased due to variations in the height of the bump-shaped electrodes, which is necessary for the bump-shaped electrodes with high bumps. There is a problem in that the above pressing force is applied and damages the pad, which is the base of the bump, to the extent that it causes cracks. In addition, in the process of forming the inner lead after connecting the inner leads, more bending stress than necessary is applied to the neck of the connecting part of the connected inner lead, which often causes the inner lead to break at the neck of the connecting part. There is a problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inner lead bonding method that can connect inner leads with high reliability without applying excessive stress to the connecting portion, in order to solve this problem.

[Means for Solving the Problems] One inner lead bonding method of the present invention includes a plurality of bump-shaped electrodes formed along the periphery of a semiconductor chip on which an integrated circuit is formed on one principal surface, and Corresponding to this, an inner lead bonding method for connecting a tip of an inner lead formed on a tape includes a step of bending the inner lead in advance so that the tip of the inner lead approaches the bump-shaped electrode side. After this step, the tip of the heated inner lead is bent back and brought into contact with the bump-shaped electrode by elastic repulsive force, and the solder of the bump-shaped electrode is melted and connected. It is said that

Further, in another inner lead bonding method of the present invention, in the bending step, the inner lead is bent toward the bump-shaped electrode, and the tip portion thereof is bent back parallel to the surface of the semiconductor chip. It is characterized by the presence of

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) and 1(b) are partial cross-sectional views of a semiconductor chip and a bonding apparatus shown in order of steps to explain an embodiment of the inner lead bonding method of the present invention, and FIG. FIG. 3 is a partial cross-sectional view showing a connected state. In this inner lead bonding method, first, as shown in FIG. 1(a), a tape 5 to which an inner lead 3 is bonded with an adhesive 4 is moved by a sprocket (not shown), and a semiconductor chip is inserted into a hole in the tape 5. is positioned on the die 9a. Next, spring 1
The tape 5 is pressed against the die 9a via the pad 11 by the repulsive force of 2, and the inner lead 3 is pressed against the molding surface of the die 9a using a rubber punch 10a. As a result, the inner lead 3 is formed into an inner lead 3a whose tip end is bent as shown by the two-dot chain line.
As shown in b), the insertion hole of the tape to which the inner lead 3a is adhered is positioned on the semiconductor chip 1. The heater chip 6 is lowered and brought into contact with the inner lead 3a. Next, the stage 7 is raised to bring the tip of the inner lead 3a into contact with the bump 2. The contact pressure at this time is
The purpose is to keep the springback at the tip of the bent inner lead. That is, the pressing force of the heater chip 6 is approximately zero. As a result, the heat of the heater chip 6 is transmitted through the inner lead 3a, the bump 2, which is a meniscus of the solder, is melted, and the molten solder wraps around the outer periphery of the tip of the inner lead 3a. , is connected to the bump 2 as shown in FIG.

[0011] The bending angle is set to an angle that absorbs variations in the height of the bumps 2 plus an angle that is maintained after connection. For example, if the angle of the inner lead with respect to the horizontal after connection is 30 degrees, and the angle at which bump height variations are absorbed and contact pressure is applied by springback force is 5 degrees, then the bending angle is:
The angle at which the inner lead 3a contacts the bump 2 may be 30 degrees. That is, the maximum contact pressure due to the springback of the inner lead 3a is set to the elastic repulsive force when the bending angle of the inner lead 3a is 5 degrees.

As a result, not only is it no longer possible to apply an excessive pressing force to the inner lead 3a as in the prior art, there is also an advantage that by bending the inner lead in advance, no bending stress is applied to the inner lead 3a after connection. be.

FIG. 3 is a partial cross-sectional view showing a state in which inner leads are connected, for explaining another embodiment of the inner lead bonding method of the present invention. In this inner lead bonding method, the inner lead 3b is attached to the tape 5 in the inner lead bending process before thermocompression bonding.
The inner leads 3b are bent at right angles near the inner leads 3b, and the tips of the inner leads 3b are bent back to form the tips parallel to the surface of the semiconductor chip 1. The subsequent connection process is the same as in the previous embodiment.

This embodiment has the advantage that the portion of the inner lead exposed from the semiconductor chip 1 can be made shorter, so that deformation of the inner lead is less likely to occur and misalignment during connection is eliminated.

[0015]

As explained above, the present invention bends the inner lead so that its tip approaches the bump electrode side before connecting it to a bump-shaped electrode, and bends the heated tip back. Contacting the bump-shaped electrode with a repulsive force transfers heat and melts the solder of the bump-shaped electrode to connect the inner lead and the bump-shaped electrode, thereby applying excessive pressing force and damaging the semiconductor chip. This has the effect of providing an inner lead bonding method that allows for more reliable connections without having to do so.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a semiconductor chip and a bonding apparatus shown in the order of steps for explaining an embodiment of the inner lead bonding method of the present invention.

FIG. 2 is a partial cross-sectional view showing a state in which inner leads are connected to bumps.

FIG. 3 is a partial cross-sectional view showing a state in which inner leads are connected to explain another embodiment of the inner lead bonding method of the present invention.

FIG. 4 is a partial cross-sectional view of a semiconductor chip and a bonding apparatus shown in the order of steps for explaining an example of a conventional inner lead bonding method.

FIG. 5 is a partial cross-sectional view showing an example of a state in which inner leads are connected to a semiconductor chip.

[Explanation of symbols]

1 Semiconductor chip 2 Bumps 3, 3a, 3b Inner lead 4 Adhesive 5 Tape 6 Heater chip 7 Stage 8 Carriage 9, 9a Die 10, 10a Punch 11 Pad 12 Spring

Claims (2)

[Claims] 1. A plurality of bump-shaped electrodes formed along the periphery of a semiconductor chip on which an integrated circuit is formed on one principal surface, and tips of inner leads formed on a tape corresponding to the bump-shaped electrodes. In the inner lead bonding method, the inner lead is bent in advance so that the tip of the inner lead approaches the bump-shaped electrode, and after this step, the tip of the inner lead is heated. An inner lead bonding method comprising the step of contacting the bump-shaped electrode with an elastic repulsive force of bending back and melting the solder of the bump-shaped electrode to connect the bump-shaped electrode. 2. The inner lead bonding according to claim 1, wherein the inner lead is bent toward the bump-shaped electrode, and a tip end thereof is bent back parallel to the surface of the semiconductor chip. Method.