JPS6035526A - Wire bonding method - Google Patents

Abstract

PURPOSE:To form the first bonding part in a stabilized manner by a method wherein a bonding tool is moved back in the state wherein a wire is engaged to the second bonding part, thereby enabling to forcedly pull out the wire and to prevent the non-movement of the wire and the like due to sliding resistance. CONSTITUTION:After the first bonding part has been formed on the electrode pad of the pellet of a semiconductor device 1, the wedge 10 as a bonding tool is moved on a lead, and the second bonding part 19 is formed. A tail stretching is performed in the state wherein the tip of a wire 11 is engaged with the second bonding part 19, the wire 11 is brought in the same state as it is forcedly pulled out from a wedge inserting hole 10a in stretched form, the wire is not clogged in the inserting hole 10a or curvedly deformed, and the length of the wire 11 protruded from the inserting hole 10a can be formed uniform. When the wire 11 is cut at a folding point 20, the tail length from the cut end to the wedge 10 becomes next first bonding part.

Description

[Detailed description of the invention] [Technical field] The present invention relates to wire bonding technology.

[Background Art] In the manufacture of semiconductor devices, a wire bonding device is sometimes used to electrically connect the electrode pad of a pellet on which an integrated circuit or the like is formed to an external lead. , a bonding tool (hereinafter referred to as a US bonder) that presses the end of the rewie 4 with a wedge and applies ultrasonic energy for bonding may be considered.

In such a US bonder, it is considered necessary to provide bonding at the end of the bonding wire for pressing with a sear. A possible technique for bonding at the first bonding end is to push out the cut end of the wire from the wedge after cutting the wire of the preceding second bonding.

However, with the technology to create a bond by extruding the wire from a wedge, it is said that due to the sliding resistance between the wire and the wedge, the wire may become jammed or deformed, making it impossible to obtain the desired bond. The present inventor has revealed that there is a problem.

[Object of the Invention] An object of the present invention is to provide a wire bonding technique that can stably obtain proper bonding.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the Invention] A brief overview of typical inventions disclosed in this application is as follows.

That is, by moving the bonding tool relatively away from the second bonding part before the wire cutting operation after the second bonding, the wire is forcibly pulled out from the bonding tool to avoid clogging of the wire due to sliding resistance. It was designed to do so.

[Embodiment] FIG. 1 is a schematic front view showing a US bonder which is an embodiment of the present invention, and FIGS. 2 and 3 are enlarged partial sectional views showing the operation.

In this embodiment, this US bonder includes a θ table 2 that holds a semiconductor device 1 as a bonded object upward, and an XY table 3 on which a bonding mechanism is mounted.
A support 4 is erected on the XY table 3, and an arm 5 is pivotally supported at the middle part of the support 4 so as to be rotatable in the downward direction. The arm 5 is configured to perform regular vertical movements by a digital head 6 installed on the XY table 3.

A vibrator 7 is installed at the end of the arm 5 on the θ table 2 side, and an ultrasonic oscillator 8 is connected to the vibrator 7. An ultrasonic energy transmission member (hereinafter referred to as a pawn) 9 is connected to the arm 5 so as to be able to transmit energy from the vibrator 7 and is supported almost horizontally, and a wedge as a bonding tool is attached to the tip of the horn 9. 10 is mounted almost vertically. The tip of the wire 11 wound around the reel 12 is inserted through the insertion hole 10a at the lower end of the wedge 10.

A clamper support 13 is fixed to the tip of the arm 5, and a clamper holder 14 is pivotally supported in the middle of the support 13 so as to rotate in a substantially vertical plane parallel to the extension direction of the horn 9. It is suspended vertically. This holder 14 is configured to perform regular reciprocating motion by a clamper moving mechanism 15 installed on the support 13. A clamper 16 in the form of a clamping tool is attached to the lower end of the boulder 14.
The clamper 16 is suspended so as to be able to open and close in a direction perpendicular to the direction of extension of the bone 9, and the clamper 16 is opened and closed by an opening and closing device 17, which includes an electromagnetic plunger or the like, provided at the upper part. The clamper 16 is arranged so that its lower end can clamp the wire 11 when the clamper 16 is opened.

Note that each digicle head, clamper opening/closing device, ultrasonic oscillator, etc. are controlled by a sequence programmed in advance in a computer or the like.

Next, the action will be explained.

After forming the first bonding portion 18 on the electrode band of the pellet in the semiconductor device 1 held on the θ table 2, the wedge 10 is moved onto the lead in the semiconductor device 1, and its lower surface presses the wire 11 against the lead. At the same time, by applying ultrasonic energy from the ultrasonic oscillator 8, a second bonding portion 19 is formed, as shown in detail in FIG.

When the second bonding part 19 is formed, for example,
By moving the Y table 3 in the X direction and the arm 5 upward by the digital head, the wedge 10 is separated from the second bonding part 19, as shown in detail in FIG. Due to this separation, the wire 11 is relatively pulled out from the insertion hole 10a of the wedge 10, and the tail is pulled out. At this time, the tip of the wire 11 remains locked to the second bonding portion 19, so that the wire 11 is forcibly pulled out from the wedge insertion hole 10a under tension. Therefore, the insertion hole 10a may be clogged with the wight 11,
The wire 11 is not curved and deformed, and the length of the wire 11 protruding from the insertion hole 10a becomes a desired value by controlling the moving distance of the XY table 3, and this value can be kept constant at all times without variation.

When the wire 11 from the wedge 10 is tailed to a predetermined length, the clamper 16 is closed and the wire 11 is clamped. Next, the wedge lO is placed on the XY table 3.
and the clamper 16 is slightly moved back and forth in the X direction. Due to this slight movement, a crease is formed at the root of the wire 11 where it connects to the second bonding part 9 (broken line arrow 2o in FIG. 3).
reference).

When the crease is formed, the clamper moving mechanism 15 moves the clamper 16 in a direction opposite to the direction in which the tail of the wire moves away from the second bonding portion 19, and the wire 11 is pulled. This allows the wire 11 to be pulled accurately from the fold.

The tail length from the cut end of the wire 11 cut from the crease to the wedge 10 becomes the bonding value in the next first bonding, but the value of this bonding value is because the tail length is always constant as described above. ,
It becomes an extremely stable constant value.

The wedge 10 in which the predetermined bonding has been created is
The semiconductor device 1 is moved to the next first bonding position in the semiconductor device 1 by the XY table 3 (the θ table 2 may be moved at the same time) and the arm 5. Then, by lowering the arm 5, the wedge 10 lays down the bonding created as described above, and ultrasonic energy is applied to perform the first bonding. At this time, since the bonding is maintained at a predetermined value and the direction of its extension coincides with the direction of ultrasonic vibration of the wedge 10, a stable bonding state is created.

Thereafter, the above-described operations are repeated, and bonding for the entire semiconductor device 1 is stably performed at a constant quality level.

[9J results] (1) By retreating the bonding tool while the wire remains locked in the second bonding part,
Since the wire can be forcibly pulled out from the bonding tool under tension, it is possible to prevent the wire from becoming jammed or bent due to sliding resistance, which would occur when the wire is pushed into the bonding tool and then fed out. It can be produced stably all the time.

(2) By stably creating bonding, the quality of bonding can be stabilized.

(3) In the wedge, which is a bonding tool that has directivity to the wire, by pulling the wire out of the wedge and creating stable bonding,
Bonding quality improvement 9) x effects become more pronounced.

(4) By forming a crease in advance when cutting the wire, the cutting point of the wire can be positioned at the crease, so that bonding can be made more stable.

(5) With the wire connected to the second bonding part, the XY table is moved to take out the tail of the wire from the bonding tool, so the wire can be cut by moving the XY table, so the clamper can open and close. It is sufficient if the wire can be cut, and the wire cutting operation is unnecessary. In other words, since a clamper moving mechanism is not required, the apparatus can be simplified.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, it can also be applied to a vertical feed type wedge in which the wire is fed out perpendicularly to the bonding surface, and this type has a particularly significant effect because of the increased frictional resistance.

[Field of Application] In the above explanation, the invention made by the present inventor was mainly applied to the US bonding technology, which is the field of application that formed the background of the invention, but the invention is not limited thereto. Can also be used for wire bonding technology, etc.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view showing one embodiment of the present invention, and FIGS. 2 and 3 are enlarged partial sectional views for explaining the operation. 1... Semiconductor device (body to be bonded), 2... θ
Table, 3...XY table, 4°13...Support, 5...Arm, 6...Digital head, 7
... Oscillator, 8... Ultrasonic oscillator, 9... Horn (ultrasonic transmission member), 10... Wedge, 11...
Wire, 12... Reel, 14... Holder, 15.
... Clamper moving mechanism, 16... Clamper, 17...
・Clamper opening/closing device.

Claims (1)

[Claims] 1. Wire bonding the first bonding part and the second bonding part, and then separating the bonding tool guiding the wire from the second bonding part, thereby removing the wire from the bonding tool. A wire bonding method, which comprises: exposing the tail of the wire, and then separating the wire from the second bonding portion. 2. The wire bonding method according to claim 1, wherein an ultrasonic wire bonding wedge is used as the bonding tool.