JPH0344041A - Bonding method - 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 [Industrial Application Field] The present invention relates to an inner lead bonding method, an outer lead bonding method, a transfer bonding method, and a pellet bonding method, and particularly to a method for vertically driving a tool.

[Prior Art] For example, a conventional inner lead bonding device has a structure as shown in FIG. That is, the tab tape 4 is attached to the electrode 3 of the semiconductor element 2 positioned and mounted on the stage l.
An inner lid 5 provided on the inner lid 5 is bonded by a tool 6. The tool 6 is fixed to a tool holder 7, and the tool holder 7 is provided so as to be movable up and down via a cross roller guide 9 on a bonding head 8 which is driven in the XY force directions by a drive means (not shown). The tool holder 7 is moved up and down by an air cylinder 10 fixed to the bonding head 8, and compressed air is supplied to the air cylinder 10 through a pressure regulator 11 and a valve 12.

Next, after the electrodes 3 of the semiconductor element 2 and the inner leads 5 of the tab tape 4 are positioned, the valve 12 is turned on. As a result, compressed air is supplied to the air cylinder 10, the tool 6 descends, presses the inner lead 5 against the electrode 3, applies a certain pressing force for a certain period of time, crushes the inner lead 5 and the electrode 3, and performs bonding. do. Valve 12 is then turned off and tool 6 is raised.

Note that, for example, Japanese Patent Application Laid-open No. 105972/1984 is related to this type of device.

[Problems to be Solved by the Invention] In the prior art described above, the collapse of the inner lead 5 and the electrode 3 depends on the application time for applying a constant pressing force. However, control based on the application time of a constant pressing force is not possible with tool 6.
There was a problem in that the amount of collapse of the inner lead 5 and electrode 3 changed each time depending on the quality of heat conduction from the inner lead 5 to the electrode 3, resulting in poor bonding quality.

This will be explained with reference to FIG. In the same figure, Pl
indicates the pressing force, and Z indicates the lowered position of the tool 6. Also electrode 3
Let Zsl be the optimum amount of collapse. Therefore, for example, if the bonding time T1 is set so as to obtain the optimum amount of collapse Zsl in bonding when heat transfer from the tool 6 is poor, the tool 6 will take a trajectory Z as shown by a solid line. Therefore, the bonding when the heat transfer from the tool 6 is good is a locus Z2 as shown by the dotted line, and the crushing tl at this time is Zs, which is larger than Zs2.

An object of the present invention is to provide a bonding method that can improve bonding quality.

[Means for Solving the Problems] The purpose of the bonding method is to press the lead and the handle with a tool to bond the lead and the electrode. This is achieved by continuing the constant pressing force from the lowered position of the tool until a certain amount of depression of the tool is obtained, thereby controlling the amount of collapse of the electrode.

[Function] The control is not based on the application time of a constant pressing force, but rather the position control is from the position where the vine presses the lead and reaches a certain pressing force until the tool descends a certain amount with a constant pressing force. Also, the amount of collapse of the electrode is constant, and the quality is stable.

[Example] An example of the present invention will be described below with reference to FIGS. 1 and 2. Note that the same members as in FIG. 4 will be described with the same reference numerals. A load converter 20 that converts changes in load into voltage and outputs the voltage is fixed to the tool holder 7, and a vertically movable arm 21 having a horizontal portion 21a at one end is fixed on the load converter 20.

On the other hand, a motor 22 is fixed to the bonding head 8, and a rotary plate 23 is eccentrically fixed to the output shaft 22a of the motor 22. Two bearings 24 are attached to the rotary plate 23 to sandwich the horizontal portion 21a of the vertically movable arm 21 from above and below.

The output signal of the load converter 20 is input to a load signal setting device 30 that outputs a command value for the set load, and the command value output from the load signal setting device 30 is input to a motor control section 31 that controls the motor 22. be done. In addition, the output of a position detector 32 such as an encoder device connected to the motor 22,
That is, the amount of vertical movement of the tool 6 is input to the motor control section 31. Although not shown, the tool 6 has a built-in heater for heating the vine.

Next, the effect will be explained. Tool 6 is Innarito 5
It is activated from a more distant upper position. As the output shaft 22a of the motor 22 rotates, the rotary plate 23 rotates, the vertical arm 21 lowers, and the tool holder 7 and the crane 6 are lowered via the load converter 20.

When the tool 6 contacts the inner lead 5 and presses the inner lead 5 against the electrode 3 as shown in FIGS. 1 and 2(a), the output voltage of the load converter 20 changes. In response to the contact signal from the load converter 20, a command value for setting is output from the load signal setter 30, and this command value is input to the motor control section 31. Thereby, the motor control unit 31 controls the motor 22 so that the set load is obtained. The point where this set load is obtained is treated as the starting point for the tool 6 to sink. The position of the tool 6 at this starting point is detected by the position detector 32.

During this time, the inner lead 5 and the semiconductor element 2 are heated by the temple 6, so the inner lead 5 and the electrode 3 begin to soften and deform. With this deformation, the output signal from the load converter 20 outputs a smaller value than before the deformation, so an output signal for applying a further load is sent to the motor control section 31 through the load signal setting device 30.

By carrying out this series of feedback control, the inner lead 5 and the electrode 3 are crushed and bonded as shown in FIG. 2(b). On the other hand, a position detector 32 attached to the motor 22 sends the vertical movement amount of the tool 6, that is, the displacement amount from the starting point of sinking, to the motor control section 31. As a result, the amount of collapse of the inner lead 5 and the electrode 3 can be determined from the amount of displacement (amount of depression) after the tool 6 starts to sink.

Incidentally, the hardness of the inner leads 5 and the electrodes 3 and the degree of softening caused by the application of heat largely depend on variations in materials and compositions. Therefore, rather than the conventional method of bonding by setting parameters (air pressure, etc.) that are proportional to the load, that is, controlling the bonding conditions by load, the amount of collapse of the inner lead 5 and electrode 3 as in this embodiment is better. It is clearly more stable to directly manage the
Product reliability will further improve.

In addition, when controlling by load (pressing force), the amount of crushing varies depending on the number of inner leads 5 and electrodes 5 to be joined at the same time, and the difference in materials. The quantity is constant and the quality is stable.

This will be further explained with reference to FIG. In the same figure,
P2 indicates the pressing force, and Z indicates the lowered position of the tool 6. Further, the optimum amount of collapse (sinking amount) of the electrode 3 is assumed to be Zs.

As described above, in this embodiment, the position is controlled, so when the heat transfer from the tool 6 is poor, the bonding takes a trajectory Z3 as shown by the solid line, and the bonding time becomes T3. Further, when the heat transfer from the tool 6 is good, bonding takes a trajectory Z4 as shown by a dotted line, and the bonding time becomes T4, which is shorter than T3.

Although the inner lead bonding method has been described in the embodiment described in "-," it goes without saying that the present invention can also be applied to outer lead bonding methods, transfer bonding methods, pellet bonding methods, and the like.

[Effects of the Invention] As is clear from the explanation in 1- below, according to the method of the present invention, since the tool is lowered by a certain amount from the position where the tool presses the lead and reaches a certain pressing force, the lead and electrode The amount of crushing is constant and the quality is stable.

[Brief Description of the Drawings] Fig. 1 is a partially sectional front view showing one embodiment of the present invention;
Figures (a) and (b) show the bonding state, and A
FIG. 3 is a diagram showing the moving trajectory and pressing force of the tool, FIG. 4 is a partially sectional front view of a conventional example, and FIG. 5 is a diagram showing the moving trajectory and pressing force of the tool. 2: Semiconductor element, 3: Electrode, 4: Tab tape, 5: Inner lead, 6: Tool, 7: Tool holder, 8: Bonding spatula 21: Vertical movement arm, 23: Rotating plate, 31: Motor control unit, 20: Load converter, 22: Motor, 30: Load signal setting device, 32: Position detector. Substitute Oshiiri Benshishi 1) Side Hiki Tokuki ￥ R2 W Doriyai

Claims (1)

[Claims] (1) In a bonding method in which a lead and an electrode are bonded by pressing and heating them with a tool, the tool presses the lead and the electrode, and from the lowered position of the tool when a certain pressing force is reached, the tool A bonding method characterized in that the amount of collapse of the electrode is controlled by continuing the constant pressing force until a certain amount of sinking of the electrode is obtained.