JPS62152143A - Formation of bump - Google Patents

Abstract

PURPOSE:To obtain a favorably bonding bump by a method wherein a ball is formed at the tip of a wire inserted in a capillary and after the ball is pressed and bonded to the part to be bonded, a recessed part is formed in the wire just over the ball and the wire is made to ascend and is cut from the recessed part. CONSTITUTION:An electric torch 3 is made to oppose to the tip of a wire 2 consisting of gold, copper, Al or the likes, inserted in a capillary 1, and a ball 4 is formed on the tip of the wire 2 by generating sparks between the electric torch 3 and the wire 2. Then, the capillary 1 is made to descend, the ball 4 is pressed on an electrode pad 6, which is used as the part to be bonded, of a semiconductor element 5 and the ball 4 is fused by ultrasonic heating and is fixed to the electrode pad 6. Then, when the capillary 1 is made to ascend, a recessed part forming jig 8 having an edge part 7 comes advancing over the ball 4 to form a recessed part in the wire 2 right over the ball 4. Then, with the jig 8 made to retrogress, a clamper 11 is made to ascend pinching the wire 2. Thereby, the wire 2 is cut at the recessed part and a bump 12 is formed on the pad 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for completely forming bumps for connecting external terminals on four-pole pads of a semiconductor device.

[Technical view of the invention and one point in between] When connecting a single-pole pad of a semi-quad element and an external terminal in a t-air manner, so-called wire bonding is known, in which the two are connected with a wire. . However, in the case of wire bonding, since the rising height of the wire is required, there is a drawback that the overall height dimension cannot be made sufficiently small. Furthermore, in wire bonding, wires must be routed for each connection point, so if there are many connection points, work efficiency may be reduced.

As a method of connecting the magnetic pole pad and the external terminal to completely eliminate such defects, a bump is formed on the pole pad, and the external terminal k+H is connected to this bump. According to the bump and the connection method used, 4
Since the pole pad and the external terminal are directly bonded and fixed via the bump, the height of the bonded part can be lowered compared to when wires are used. M has the advantage that it can be bonded and fixed to the external terminal r4-pole pad in one step.

By the way, as a conventional method of forming all bumps on an electrode pad, the method disclosed in Japanese Patent Laid-Open No. 59-208751 is known. In this known technique, the entire bump is formed by wire bonding. That is, once a ball is formed at the tip of a wire inserted into a capillary, this ball is bonded to a bonding pad.

Thereafter, a bump is formed on the pad by tearing off the wire with a clamper or the like.

However, if the wire is torn off by a clamper, the length of the wire remaining in the ball is not constant. Then, after positioning the external terminal above the bump in such a state, if you use /JOE and heat to bond it, the bonding condition between the external terminal and the bump, that is, the bond strength 1ri, will be constant. There may be disadvantages such as failure or poor bonding.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a bump forming method that makes it possible to keep the shape of the bump constant when the bump is formed using wire bonding.

[Summary of the invention]

In this invention, a ball is formed at the tip of a wire inserted into a capillary, this ball is joined to a part to be joined by IIprE, a recess is formed in a portion of the wire directly above the ball, and then the wire is pulled. By cutting the lever wire 14fi from the recessed portion, the length of the wire remaining on the ball is made constant.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

First, as shown in Figure 1, a wire 2 made of a material such as aluminum is inserted into a capillary 1.
A ball 4t is formed at the tip of the wire 2 by interposing a pair of torches 3 to the tip of the wire 2 and generating sparks between them and the wire 2. Next, as shown in FIG. 2, the capillary 1 is lowered to bulge onto the magnetic pole pad 6 of the semiconductor element 5, which is a temporary bonding part, and generate heat. Since the transmission is via the element 5, the ball 4 is connected to the electrode pad 6.
It will be fixed to.

After the ball 4 is fixed to the electrode pad 6, the capillary 1 is raised as shown in FIG. Next, a recess forming jig 8 having a sharp edge 7 above the ball 4 moves forward to form a recess y2 on the wire 2 directly above the ball 4 as shown enlarged to 46+sL.

When the recess 9 is formed in the wire 2, the recess forming jig 8
As the capillary 1 moves back, as shown in Fig.
A clamper 1 provided above holds the wire 2,
In this state, the clamper 11 is raised. Next, the wire 2 is cut from the recess formed by the recess forming jig 8, thereby forming a hump 12 on the electrode pad 6.

The bump 12 formed in this way is obtained by forming the recess 9 in the wire 2 in advance and then cutting the wire 2.
Since the length of the wire 2 remaining on the bump 12 is constant and the concave portion 9f is formed directly above the ball 4, it can be made sufficiently short. Therefore, when connecting the external terminal 14 extending from the synthetic resin film 13 to the Uromi bump 12 as shown in Fig. g5, not only can the bonding strength in the connected state be constant, It does not cause poor bonding.

〔Effect of the invention〕

As described above, the present invention forms a ball at the tip of a wire inserted into a capillary, press-joins this ball to a part to be joined, and then forms a recess in a portion of the wire directly above the ball, The wire was then pulled to cut the wire from the recess to form a bump. Therefore, since the length of the wire remaining in the bump can be kept constant and sufficiently short,
Not only can the bonding strength between the bump and the external terminal be constant, but also it is possible to provide a bump that does not cause poor bonding.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIGS. 1 to 5 are explanatory diagrams sequentially showing the steps for forming bumps, and FIG. 6 is an enlarged view of the state in which the wire has been completely formed with notches. DESCRIPTION OF SYMBOLS 1... Capillary, 2... Wire, 4... Ball, 6... Electrical pad (A junction, A), 8... Recess formation jig, Su... Recess, 12... bump. Applicant's agent Patent attorney Takehiko Suzue Figure 6

Claims (1)

[Claims] A step of forming a ball at the tip of the wire inserted into the capillary, a step of lowering the capillary and pressing the ball to the part to be joined, and a step of joining the ball to the part to be joined and raising the capillary. A bump forming method comprising the steps of: forming a recess in a portion of the wire directly above the ball; and pulling the wire and cutting it from the recess.