JPH0129059B2 - - Google Patents

Abstract

PURPOSE:To prevent the occurrence of an abnormal loop upon acceleration of a bonding speed by forming the outer peripheral shape of a Z-shaft cam so as to lower the rising height of a capillary chip after press-bonding the fine metal wires to a semiconductor chip from the top dead point height. CONSTITUTION:A capillary chip 2 is moved to a rising point lower from the top dead point by increasing the radius R2 of the outer periphery of the rising zone to form a loop of suitable height to the radius Ra of the outer periphery of the zone for rising the capillary chip 3 to the top dead point of a Z-shaft cam 30 which is secured to a cam shaft 10 and rotatably driven, thereby setting fine metal wires 16 in height substantially equal to the length required to form a suitable loop 16a.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a wire bonding device for connecting electrodes of a semiconductor chip and external lead terminals with thin metal wires in the manufacturing process of semiconductor devices such as ICs and LSIs.

[Prior art]

A conventional wire bonding apparatus has a configuration as shown in FIG. 1, the main parts of which are shown. Reference numeral 1 denotes a frame, which is mounted on an XY table (not shown) that moves in the X-axis and Y-axis directions, and supports the bonding head. 2 is a capillary tip, which is attached to the tip of the capillary arm 3. A support member 4 has the capillary arm 3 attached to one side, and a transmission arm 5 is attached to the other side, and is rotatably supported by a support pin 6 fixed to the frame 1.
7 is a mounting body attached to the other side of the transmission arm 5;
A tension spring 8 is attached between the frame body 1 and the other end side, and the capillary tip 2 is attached with the support pin 6 as a fulcrum.
Spring pressure is applied in the direction of rotation in which the
Reference numeral 9 denotes a Z-axis cam, which is driven and rotated by a drive motor (not shown) attached to the frame 1 via a camshaft 10. 11 is a support pin 1 fixed to the frame body 1
A contact 13 fixed to the front end of the transmission lever is rotatably supported by the transmission lever 2, and a contact 13 fixed to the front end abuts on the mounting body 7, and a tension spring 14 is installed between the rear end and the frame 1, A rotational force is applied in a direction that pushes down the body 7. The transmission lever 11 has a roller 1 on the rear end side.
5 is attached, and is in contact with the outer peripheral surface of the Z-axis cam 9 and is rotated in the vertical direction, moving the contactor 13 side in the vertical direction, thereby causing the capillary tip 2
moves downward and upward. Reference numeral 16 denotes a thin metal wire drawn out from a spool (not shown) disposed above and passed through the capillary tip 2.

Next, a semiconductor chip 17 is bonded onto the die pad portion 18a of the lead frame 18, and wire bonded to the electrode and the external lead terminal 18b of the lead frame 18 using the thin metal wire 16.
16a is a loop formed in the thin metal wire 16, 19
is a pedestal on which the lead frame 18 is placed and heated.

One cycle of the operation of the capillary tip 2 of the above-mentioned conventional device is shown in explanatory diagrams in sequence in FIG. 2, and the relationship between the rotation angle of the Z-axis cam 9 and the amount of vertical movement of the capillary chip 2 is shown in a curved diagram in FIG. . θ represents the rotation angle of the Z-axis cam, and L represents the moving height of the capillary tip 2.

The wire bonding operation of the capillary chip 2 will be explained with reference to FIGS. 2 and 3. First, capillary tip 2 is placed at the top dead center height _H1 (second
It starts descending from the point a) in FIG. 3 (section A in FIG. 3), passes through the position b in FIG. The balls formed in the capillary chip 2 are joined by thermocompression bonding (or even ultrasonic pressure welding). Next, capillary tip 2 begins to rise, and at the same time the XY table (not shown)
begins to move, and capillary tip 2 is at the top dead center height.
It rises to H ₁ (Fig. 2 d, e, first half section of Fig. 3 C). Subsequently, the capillary chip 2 begins to descend as shown in FIG. section). Here, the thin metal wire 16 is joined by the capillary chip 2 by thermocompression bonding (or even ultrasonic pressure welding). As a result, a wire bond chevron-shaped loop 16a of the thin metal wire 16 is formed. Then, the capillary tip 2 begins to rise (FIG. 2j), and in the middle of its rise, the thin metal wire 16 is pinched and pulled off by a clamping device (not shown), and the thin metal wire 16 is pulled out from the tip of the capillary tip 2. After the required length remains, it ascends and returns to top dead center (section K in Figure 2 and E in Figure 3). Next, capillary chip 2
An electric torch electrode 20 enters below the metal wire 16, and by applying a high voltage, an electric spark is generated at the lower end of the thin metal wire 16, and the ball 16b is formed by melting due to high heat (Fig. 2l), completing one cycle of wire bonding. do.

The correspondence between Fig. 2 and Fig. 3 is that a, b are A section, c
The time of landing is the crimping time in section B. d~h are C
A loop is made in the thin metal wire 16 in the section. i is the landing time in the D section, and j to l is the E section, during which the ball 16a is formed.

Conventional wire bonding equipment uses thin metal wire 1
In order to form the ball 16a at the lower end of the capillary chip 6, a space is required to insert the electric torch electrode 20 under the capillary chip 2.
H ₁ is set high. Taking this height H ₁ as the reference for the top dead center, the outer circumferential radius R _a for the top dead center of the Z-axis cam 9 and the outer circumferential radius for loop formation.
R ₁ was the same, and the height increased during loop formation was also increased by H ₁ . As shown in Figure 2e,
A length of _H1 will come out from the bottom end of capillary tip 2. The length of _H1 of this thin metal wire 16 is
Since the length is too long compared to the length required to form the loop 16a, especially when the wire bonding speed is increased, the thin metal wire 16 becomes susceptible to the slippage and back tension of the capillary tip 2, and when lowered, the metal wire 16 becomes susceptible to the slippage and back tension of the capillary tip 2. The phenomenon of not being able to return upwards often occurs, and loop 16
There was a drawback that an abnormality in which the mountain shape of a became too large was likely to occur.

[Summary of the invention]

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional device, and the height of the rise of the capillary chip after the thin metal wire is crimped onto the semiconductor chip is made lower than the height of the top dead center, and the thin metal wire An object of the present invention is to provide a wire bonding apparatus in which the wire is raised by approximately the same distance as the length required to form an appropriate loop, thereby preventing the occurrence of loop abnormalities due to an increase in the bonding speed.

[Embodiments of the invention]

FIG. 4 is a configuration diagram showing the main parts of a wire bonding apparatus according to an embodiment of the present invention.
8, 10 to 19, 16a, 18a, and 18b are the same as those in the conventional device, and their explanation will be omitted.

30 is Z fixed to the camshaft 10 and driven and rotated.
It is a shaft cam, and the outer radius _R2 of the rising section for forming a loop of an appropriate height is made larger than the outer circumferential radius R _a of the section in which the capillary tip 2 is raised to the top dead center. is set at a rising point lower than the top dead center so that the height of the thin metal wire 16 is approximately equal to the length required to form a suitable loop 16a.

One cycle of operation of the capillary chip 2 of the apparatus of the above embodiment is shown in explanatory diagrams in order in FIG.
The relationship between the rotation angle of the Z-axis cam 30 and the amount of vertical movement of the capillary tip 2 is shown in a curve diagram in FIG.

Figure 5 a-c, i-l are from Figure 2 a-c, i-l
6A, B, C, D, and E are the same as FIG. 3A, B, C, D, and E. Figure 5c
After being crimped onto the semiconductor chip 17 by the ball 16a of the thin metal wire 16, the capillary chip 2 begins to rise, as shown in d, until the Z-axis cam 30 raises it to a height _H2 . This height _H2 is lower than the top dead center height _H1 , and is approximately equal to the length required to form a loop due to the descent of the capillary tip 2 from the rising point shown in e to h and the movement of the XY table. be.

This is shown in section C in FIG. 6, and the rising height _H2 of the capillary chip 2 is set to satisfy _H2 < _H1 .

In the above embodiment, the rotational movement of the capillary arm 3 that raises and lowers the capillary tip 2 is as follows:
Although the rotation of the Z-axis cam 30 is transmitted via the transmission lever 11, the present invention is not limited to this. For example, the movement of the outer circumferential portion of the Z-axis cam may be directly transmitted to the transmission arm on the opposite side of the capillary arm for rotation. good. In this case, the outer peripheral shape of the Z-axis cam is the Z-axis cam 3 shown in FIG.
It will be different than 0.

Further, when wire bonding is performed by adding ultrasonic pressure bonding to thermocompression bonding to bond the thin metal wire 16, the capillary arm should have an ultrasonic oscillator attached to its rear end.

〔Effect of the invention〕

As explained above, this invention changes the outer circumferential shape of the Z-axis cam and reduces the height required to form a loop when moving a capillary chip onto an external lead terminal after crimping a thin metal wire to a semiconductor chip. Since the distance is approximately the same as the length and is lower than the height required to form a ball at the tip of the thin metal wire, wire bonding with a suitable loop formed is possible, quality is improved, and the time required for loop formation is shortened. (The angular distribution of the Z-axis cam can be made smaller), the Z-axis cam can have a sufficient bonding time, and the wire bonding speed can be increased.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing the main parts of a conventional wire bonding device, Figure 2 is an explanatory diagram sequentially showing one cycle of the operation of the capillary chip in Figure 1, and Figure 3 is a diagram showing the rotation of the Z-axis cam in Figure 1. A curve diagram showing the relationship between the angle and the amount of vertical movement of the capillary chip, FIG. 4 is a configuration diagram showing the main parts of a wire bonding device according to an embodiment of the present invention, and FIG. 5 shows one cycle of operation of the capillary chip in FIG. 4. FIG. 6 is a curve diagram showing the relationship between the rotation angle of the Z-axis cam in FIG. 4 and the amount of vertical movement of the capillary tip. 2... Capillary chip, 3... Bonding arm, 5... Transmission arm, 11... Conduction lever, 16...
...Thin metal wire, 16a...Loop, 17...Semiconductor chip, 18b...External lead terminal, 30...Z
axis cam. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. In a device that wire-bonds a semiconductor chip and an external lead terminal with a thin metal wire by raising and lowering a capillary chip attached to the tip of a bonding arm, the capillary chip is bonded to the semiconductor chip and moved to the next external lead terminal. At this time, the height of the capillary tip is raised from the bottom dead center by approximately the same distance as the length required to form an appropriate loop of the thin metal wire, and the height required to form a ball at the tip of the thin metal wire is increased. A wire bonding device characterized by being lower than the height.