JPH0449631A - Wire-bonding method - Google Patents

Abstract

PURPOSE:To enable adhesion strength of wire bonding to be improved and scattering of the adhesion strength to be reduced by further striking at least near a second bond of the second bonded wire in connection by wire bond. CONSTITUTION:A wire 36 is used to connect an electrode part 33 of a bare chip IC 32 which is mounted on a circuit board 31 and an electrode part 37 which is provided on a wiring 35 near the bare IC chip 32. Then, a wire ball which is formed on the wire which jumped from a tip of a capillary due to electrical discharge is welded on the wire near a second bond neck part of the wire 36 which is thus connected by using pressure which is applied to the capillary and ultrasonic energy in piles and the wire is pulled out by pulling up the capillary, thus forming a ball 39. A lower surface periphery of the struck ball 39 in tiles in this manner is firmly welded onto a surface of the electrode part 37 of the wire 35 which also holds down the wire 36 which is connected initially, thus enabling welding strength to be reinforced.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a C0B (chip/ On board) module mold package type hybrid I
C1 further relates to a wire bonding method for connecting a capacitor, a resistor, etc. to a circuit board or the like by wire bonding.

(Prior Art) Conventionally, as technologies in this field, there have been the following, for example.

FIG. 6 is a plan view of a conventional semiconductor device, and FIG. 7 is a sectional view of the semiconductor device.

As shown in these figures, the first electrode portion 4 of the paired chip IC 3 mounted on the circuit board l and the circuit board 1
The second electrode part 5 of the upper wiring 2 is connected with a wire 6. At this time, in the normal ball bond method, the paired chip IC3
The first bond is welded as shown in 7 by crushing a ball formed by electric discharge with a capillary to which pressure and ultrasonic energy are applied. On the other hand, the second electrode part 5gg slides the capillary using pressure and ultrasonic energy,
The paired chip IC 3 and the wiring 2 are electrically connected to each other by a wire 6 .

(Objective to be Solved by the Invention) However, in the wire bonding method described above, due to the difference in welding shape between the first bond side and the second bond side, the welding strength of the wire is higher on the second bond side. No matter how you manage the bonding conditions, the welding strength on the second bond side will vary greatly, so the connection reliability of the finished product will not improve.In particular, the height of the paired chip IC and the connection distance may The welding strength on the bonding side of No. 2 becomes significantly weaker.

For example, as shown in FIG. 8, the height of the IC chip 10 is low, and the distance ll1 between the first bond 11 and the second bond 12 is
In the case where lL1 is long, as shown in FIG.
Comparing the case where the distance Lt is short in 7, as shown in FIG. 9, the rise on the second bond side becomes obtuse, and the neck part of the second bond of the wire 18 has a large gap as shown in 19. . Therefore, unlike in Fig. 8, the welding area A becomes smaller, the welding strength decreases, the shape becomes unstable, and the welding strength also varies.In such a state, if a package is applied by molding etc., the finished product will be a wire. This results in breakage, which lowers the yield after molding. In addition, recently there has been a trend toward higher density packaging and smaller packages, and in order to meet these demands, bonding machines have been repeatedly improved, and as shown in Figure 10, the conditions of bonding machines have been changed. According to
There is a method of bonding while shaping the wire into a U-shape in the middle. However, even in this case, bonding is performed while the machine controls the loop shaping of the wire, resulting in an extremely low bonding speed.

Therefore, it takes a considerable amount of time to bond an IC with a large number of pins, and as described above, variations in welding strength on the second bond side are unavoidable.

The present invention has the above-mentioned features, especially when the height of the IC chip is high,
This results in a decrease in the welding strength of the second bond when the distance between the first bond and the second bond is short, a large variation in the welding strength, and an extreme decrease in bonding speed due to the wire shaping control of the bonding machine. In order to avoid this problem, balls obtained by electric discharge are overlapped and struck onto the wire at the second bond neck part of the wire bonded using the conventional technique. This improves the welding strength and reduces the variation in the welding strength, thereby improving the connection. An object of the present invention is to provide a wire bonding method with excellent reliability.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a wire bonding method that includes a first bonding step applied to an electrode portion of a mounted component, and a first bonding step performed on an electrode portion of a mounted component; A second bonding step is performed on the connection electrode portion of the mounting component, and a wire ball is stacked on the electrode portion of the mounted component and/or the connection electrode portion, and the wire and ball are welded, and the periphery of the lower surface of the wire ball is connected. A bonding process is performed to weld the wire to the surface of the electrode portion around the wire.

Furthermore, as shown in FIG. 2, a first ball bonding process is performed on the electrode part of the mounted component, and a second bonding process is performed on the connection electrode part arranged near the mounted component. ,
A third bonding process is performed in which a wire ball is stacked and struck on the connection electrode part to weld the wire and the ball, and the periphery of the lower surface of the wire ball is welded to the surface of the electrode part around the connected wire. It is.

(Function) According to the present invention, as described above, since the balls obtained by electric discharge are overlapped and struck onto the wire at the bonding portion of the wire bonded using the conventional technique, the bonding portion becomes robust. The wire welding strength is approximately doubled and can approach the strength of the wire itself.

Furthermore, variations in wire welding strength can be reduced to about 1/2.

For example, as shown in FIG. 2, by further striking a wire ball over the wire of the second bond part of the bonded wire in the same manner as that made on the first bond part side, The initially bonded wire and the second bond portion are simultaneously welded.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of a wire bonding process showing an embodiment of the present invention, and FIG. 2 is a plan view of a semiconductor device obtained by applying the present invention.

First, as shown in FIG. 1(a), a wire 36 is connected between the electrode part 33 of the paired chip IC 32 mounted on the circuit board 31 and the electrode part 37 provided on the wiring 35 near the paired chip IC 32. Connect using That is, first,
A ball 3 made by electric discharge on the electrode part 33 of the paired chip IC 32 using a conventional method is pressed by the ultrasonic energy and pressure transmitted to the capillary.
4 is welded, and then, while being pulled up, the pulled-out wire 36 forms a horseshoe-shaped second bond 38 on the electrode part 37 of the wiring 35 due to the pressure transmitted to the capillary and the sliding of the ultrasonic energy. It is welded and connected like this.

Next, as shown in FIG. 1(b), a wire ball is formed on the wire near the second bond neck portion of the wire 36 connected in this way by electrical discharge on the wire protruding from the tip of the capillary. are overlapped and welded using pressure applied to the capillary and ultrasonic energy, and the capillary is pulled up to tear off the wire and form a ball 39. The periphery of the lower surface of the ball 39, which is overlapped in this way, presses down the wire 36 that was first connected to the electrode portion 37 of the wiring 35, and at the same time is firmly welded to the surface of the electrode portion 37, increasing the welding strength. is strengthened.

Further, as shown in FIG.
The electrode part 44 of the high-height chip circuit component 43 fixed with the wire 4 and the second electrode part 45 on the circuit board 41 are
After connecting with 6, it may be pressed with a ball 47.

Further, as shown in FIG. 4, the electrode section 53 on the mounted component 52 mounted on the lead frame 5
After connecting the electrode portion 54 of the inner lead 51 of No. 0 with the wire 55, it may be pressed with the ball 56.

FIG. 5 is a wire welding strength characteristic diagram with and without second-side ball striking.

Compared to the conventional case where there is no second side ball striking, when there is second side ball striking as in the present invention, the wire welding strength can be approximately doubled.

Furthermore, variations in wire welding strength can be reduced to about 1/2.

In this case, the material of the wire is Au, and the diameter is 030 μm.
It was measured by pulling up the wire bonded between the mounted component and the lead frame with a hook.

Next, FIG. 11 is a sectional view of a wire bonding process showing another embodiment of the present invention.

First, as shown in FIG. 11(a), the electrode part 63 on the mounted component 62 mounted on the lead frame 60 and the electrode part 64 of the inner lead 61 of the lead frame 60 are connected with a wire 65 by the wedge bonding method. Connecting.

Next, as shown in FIG. 11(b), ball bonding is performed to the electrode portion 63 on the mounted component 62, and the electrode portion 63 is pressed down with the ball 68.

Furthermore, as shown in FIG. 11(c), the lead frame 6
Ball bonding is performed on the electrode portion 64 of the inner lead 61 of No. 0, and the electrode portion 64 is pressed down with a ball 69.

Note that after the step shown in FIG. 11(a), ball bonding is first performed on the electrode portion 64 of the inner lead 61 of the lead frame 60, and after pressing the electrode portion 64 with the ball 69, the mounting component 62 is bonded. Ball bonding may be performed on the electrode portion 63 of the electrode portion 63, and the electrode portion 63 may be pressed with a pole 68.

In this manner, when wedge bonding is performed, pole bonding can be performed overlappingly on both the first side and the second side.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described above in detail, according to the present invention, in connection by wire bonding, overlapping is performed at least in the vicinity of the second bond of the second bonded wire. Compared to the above, it is possible to improve the welding strength of wire bonding and reduce the variation in welding strength.

To obtain a product with high welding strength, suppressing variations in welding strength, and high connection reliability, especially when connecting objects with a high level difference and a short distance between the first bond position and the second bond position. I can do it.

Furthermore, as described above, by increasing the welding strength of the bond parts, it is possible to eliminate defects caused by wire breakage during puff caging with molding.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a wire bonding process showing an embodiment of the present invention, FIG. 2 is a plan view of a semiconductor device obtained by applying the present invention, and FIGS. 3 and 4 show modified examples of the semiconductor device. Figure 5 is a wire welding strength characteristic diagram with and without second side pole driving, Figures 6 and 7 are diagrams showing conventional wire bonding structures, and Figures 8 to 10 are various examples of wire bonding. FIG. 11 is a cross-sectional view showing a wire bonding process according to another embodiment of the present invention. 31, 41...Circuit board, 32...Pair chip IC
,3337,44,45,53,54,63,64...
・Electrode part, 35...Wiring, 36, 46.55.65・
...Wire, 34. , 39.47.56.68°69・
... Ball, 38... Second bond, 42... Adhesive side, 43... Chip circuit component, 50.60... Lead frame, 5262... Mounting component, 51.61...
・Inner lead. Patent Applicant Oki Electric Industry Co., Ltd. Agent Patent Attorney Mamoru Shimizu (1 other person) Modified example of the child support device of the present invention (Fig. 3) Fig. 4 E0 in F4 concave ball

Claims (2)

[Claims] (1) (a) A first bonding step performed on the electrode portion of the mounted component; (b) a second bonding step performed on the connection electrode portion disposed near the mounted component; ( c) A bonding step in which a wire ball is stacked and struck on the electrode part and/or the connection electrode part of the mounted component, and the wire and ball are welded, and the periphery of the lower surface of the wire ball is welded to the surface of the electrode part around the connected wire. wire bonding method. (2) (a) a first ball bonding process performed on the electrode part of the mounted component; (b) a second bonding process performed on the connection electrode part disposed near the mounted component; (c) overlapping and hitting a wire ball on the connection electrode part;
A wire bonding method that includes welding a wire and a ball, and a third bonding step of welding the periphery of the lower surface of the wire ball to the surface of an electrode part around the connected wire.