JP2576796B2 - TAB inner lead joining method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a TAB (Tape Automated Bo) used for mounting a semiconductor device.
The present invention relates to a bonding method and a TAB tape for bonding an inner lead of a tape carrier for bonding and an electrode of a semiconductor element.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a TAB tape has a device hole 6 for mounting a semiconductor element on a long tape carrier 1 made of polyimide and a support ring 4 for holding a Cu wiring electrode. Have been. At both ends of the width direction of the tape carrier 1, sprocket holes 5 standardized at equal pitch intervals in advance for tape positioning and transport are formed by press working. The support ring 4 is formed with an inner lead 2 protruding inside the device hole 6 and an outer lead 7 on the outside for electrical connection with a substrate on which a TAB tape is mounted. All Cu wiring electrodes including the inner lead and the outer lead are plated with 0.5 to 1 μm thick Au or Sn by electrolytic plating or electroless plating.

FIG. 4 is a schematic view showing a conventional method of connecting inner leads to the TAB tape shown in FIG. Inner lead 2 of TAB tape and semiconductor element 21
In the single-point bonding method in which the bumps 8 are formed sequentially on one of the Al electrode portion of the semiconductor element 21 and the tip of the inner lead 2 of the TAB tape, the bump 8 is formed. The bonding is performed by a bonding tool 32 through a method using both ultrasonic waves and heat. At this time, a load of 100 gf and an ultrasonic output of 150 mW are applied to the joint, and the semiconductor element 21 is heated to about 250 ° C. by the heating stage.

[0004]

In order to obtain a stable bonding strength by a single point bonding method using thermocompression combined with ultrasonic waves, the natural oxide film of Sn existing in the Sn plating layer on the inner lead surface by ultrasonic vibration should be sufficiently reduced. The condition is that a sufficient alloy layer of Sn on the inner lead surface and Au on the bump is formed by the heat energy from the heating stage. Here, sides where the ends of the inner leads are lined up are, as shown in FIG. 4, sides perpendicular to the longitudinal direction of the tape carrier 1 as a first side H1 and a second side H2, and are parallel to the longitudinal direction of the tape carrier 1. When the three sides are the third side and the fourth side, the vibration direction 33 of the ultrasonic wave applied to the ultrasonic horn 31 is the longitudinal direction of the inner lead 2 with respect to the third side H3 and the fourth side H4. And the first side H
1, a direction orthogonal to the longitudinal direction of the inner lead 2 with respect to the second side H2.

When the ultrasonic vibration 33 is applied in a direction perpendicular to the longitudinal direction of the inner lead 2 as in the first side H1 and the second side H2, the inner lead 2 moves due to the ultrasonic vibration 33. Therefore, the ultrasonic vibration 33 cannot be sufficiently transmitted to the bonding interface, and the Sn oxide film cannot be destroyed. Therefore, the joining strength of the first side H1 and the second side H2 is
There is a problem that the third side H3 is lower than the fourth side H4.

Further, when the ultrasonic output is increased in order to reduce the variation in bonding strength, the positional deviation of the inner leads increases, and there is a possibility that the inner leads may come into contact with the adjacent inner leads. There was a problem.

When the lead pitch is 100 μm or less, the lead width becomes as thin as 50 μm or less, and the lead rigidity is reduced. Therefore, the sag of the lead or the bending of the lead occurs at the time of manufacturing the TAB tape, which causes a decrease in the yield. Was.

[0008] An object of the present invention is to solve such a problem and realize a stable joint having no variation in joint strength.
An object of the present invention is to provide a TAB inner lead bonding method and a TAB tape that can be narrowed in pitch.

[0009]

SUMMARY OF THE INVENTION TAB used in the present invention
The tape is a TAB tape having an inner lead with a wiring electrode protruding inside a support ring on which a semiconductor element is mounted, and is provided with a base film for holding a tip of the inner lead.

The present invention is a method for joining the inner lead of the TAB tape and the electrode of the semiconductor element, wherein the inner lead and the electrode of the semiconductor element are aligned, and the upper end of the inner lead is clamped by a clamper. The inner lead and the electrode are sequentially joined by pressing and bonding tool.

[0011]

The TAB tape used in the present invention has a TAB tape provided by a lead holding film provided at the tip of the inner lead.
This prevents the sagging of the lead and the pitch shift due to the bending of the lead, which are generated when the B tape is manufactured, particularly when the inner lead is etched, and the yield of the TAB tape is improved, and the pitch can be narrowed.

Further, in the joining method of the present invention, the displacement of the leads due to ultrasonic vibration can be prevented by suppressing the inner leads by the clamper, and the lead joining at a narrow pitch can be performed. Furthermore, since ultrasonic vibrations are efficiently transmitted to the bonding interface, bonding can be performed with low output ultrasonic power.
The bonding stress on the semiconductor element has been reduced, and highly reliable bonding has been made possible.

[0013]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a TAB tape used in the present invention .
It is a schematic diagram showing an example . As shown in FIG. 1, the TAB tape of the present invention has a device hole 6 for mounting a semiconductor element on a polyimide long tape carrier 1 having a thickness of, for example, 100 to 125 μm and a width of 35 mm. A support ring 4 for holding a 35 μm Cu wiring electrode is formed. On both sides of the tape carrier 1 in the width direction, sprocket holes 5 standardized at equal pitch intervals are previously formed by press working for tape positioning and transport.

Outer leads 7 having a width of 100 μm and an arrangement pitch of 200 μm, for example, are formed outside the support ring 4 for electrical connection with a substrate on which a TAB tape is mounted. Inside the support ring 4, an inner lead 2 having a width of, for example, 60 μm and an arrangement pitch of 100 μm, which protrudes toward the device hole 6, is formed. In order to reinforce the inner lead 2 and prevent a lead position shift due to ultrasonic vibration during bonding, a lead made of, for example, polyimide made of the same material as the tape carrier 1 for holding the leading end from below at the tip of the inner lead 2. The holding film 3 is formed.

All Cu wiring electrodes including the inner leads and the outer leads are plated with, for example, 0.5 μm thick Sn plating by electroless plating. By providing the lead holding film 3, the yield of the TAB tape was as high as 98% or more with the TAB tape having a lead arrangement pitch of 100 μm or less.

Next, a method of bonding the inner leads to the TAB tape shown in FIG. 1 will be described.

FIG. 2 is a schematic view showing the inner lead bonding method of the present invention. As shown in FIG. 2, on the Al electrode 22 of the semiconductor element 21, electrolytic plating is performed.
For example, an Au bump 8 having a height of 20 μm and a diameter of 50 μm
Are formed.

First, after the bumps 8 of the 10 mm square semiconductor element 21 are aligned with the inner leads 2, the tip of the inner leads 2 is clamped by, for example, 20 mm.
Pressurize with 0 gf / 1 lead.

Next, the ultrasonic horn 31 is lowered, the bonding tool 32 is pushed into the inner lead 2, and the inner lead 2 and the bump 8 of the semiconductor element 21 come into contact. Further, an ultrasonic vibration 33 is applied in parallel to the direction of the ultrasonic horn 31, and the heating temperature of the semiconductor element 21 is 280 ° C.
The bonding between the inner lead 2 and the bump 8 is performed under the following conditions. At the time of joining, the joining load is applied to the bonding tool 32 by F =
With the 60 gf applied, an ultrasonic output of 100 mW (amplitude width 0.2 μm) is applied.

The above operation was performed on all the inner leads 2 to join them to the bumps 8. After that, measurement of bonding strength,
Observe the amount of displacement between the inner leads 2 and the bumps 8,
The occurrence of cracks under the surface of the Al electrode 22 was observed. As a result, the pull strength was 30 gf / lead (δ = 5) on average on all sides, and bonding was possible with little variation and practically sufficient strength. Moreover, the inner lead 2 and the Al electrode 22
Is less than 10 μm, which can be reduced to about half as compared with the conventional joining method. Furthermore, Al
It was confirmed that no crack was generated below the surface of the electrode 22.

Further, in the inner lead bonding of a semiconductor element having an outer dimension of 15 mm square and an electrode arrangement pitch of 80 μm, a highly reliable and stable bonding strength can be obtained by using the TAB tape and the bonding method of the present invention, and High-precision bonding with an inner lead misalignment of 10 μm or less can be performed.
B mounting becomes possible.

After joining the inner leads, a temperature / humidity cycle test (MIL-STD-883B) was performed as an environmental test.
). The environmental condition is that the temperature is 2
The test was performed at 5 ± 2 ° C. to 65 ± 2 ° C., 90 to 98% humidity, and 10 cycles (24 hours / cycle). According to the pull strength test after the temperature and humidity test, the strength did not decrease.

According to the present invention, the ultrasonic output can be made lower than that of the conventional thermocompression bonding using ultrasonic waves.
It has been confirmed that the mechanical stress applied to the semiconductor element is reduced, and that the present invention is also effective for bumpless bonding in which the inner lead and the Al electrode are directly bonded without using a bump.

[0025]

As described above, according to the TAB method of the present invention.
According to the method of joining the inner leads, the lead holding film can realize a stable joining with a small variation in joining strength, minimizing the displacement between the inner leads and the electrodes of the semiconductor element due to ultrasonic vibration, and There is an effect that chip and narrow pitch TAB mounting can be realized.

Further, the transmission efficiency of the ultrasonic vibration is improved, the bonding can be performed at a low output, and the bumps and the inner leads of the semiconductor element can be connected with sufficient strength without causing crack damage under the electrode surface of the semiconductor element. Has the effect of joining with high reliability.

Further, the lead holding film provided at the tip of the inner lead prevents pitch displacement due to lead sagging and lead bending, thereby improving the yield of TAB tape and realizing low cost.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a TAB tape of the present invention.

FIG. 2 is a schematic view showing a method for bonding inner leads according to the present invention.

FIG. 3 is a schematic view showing a conventional TAB tape.

FIG. 4 is a schematic view showing a conventional TAB inner lead bonding method using bumps.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tape carrier 2 Inner lead 3 Lead holding film 4 Support ring 5 Sprocket hole 6 Device hole 7 Outer lead 8 Bump 21 Semiconductor element 22 Al electrode 23 Clamper 31 Ultrasonic horn 32 Bonding tool 33 Ultrasonic vibration direction H1 First side H2 First 2 side H3 3rd side H4 4th side

Claims (3)

(57) [Claims] 1. A support ring for mounting a semiconductor element.
TAB with inner leads with wiring electrodes protruding on the side
A tape for holding a tip of the inner lead
Inner lead of TAB tape with base film
And bonding the electrode of the semiconductor element to the semiconductor device.
Position of the semiconductor lead and the electrode of the semiconductor element.
Press the upper end of the inner lead with a clamper
Then, the inner lead is connected to the inner lead by a bonding tool.
TA is characterized in that joining with the electrode is performed sequentially.
B Inner lead joining method. The top of claim 2 wherein said electrode bumps are formed, the joining method of the TAB inner lead according to claim 1, characterized by bonding the electrode and the inner lead via a bump. Wherein the base film is, the claims of the tip of the inner lead, characterized in that it held from below
2. The method for joining a TAB inner lead according to item 1.