JPS62188331A - Bonding device - Google Patents

Abstract

PURPOSE:To ensure the fixation of a lead frame by constructing an upper-side pressing member so that it comes into contact with the outer peripheral edge portion in a tab of the lead frame in such a manner that it presses down said portion. CONSTITUTION:A lower-side pressing member 12 is formed in the shape of a substantially square panel. On the upper side of this member a recessed portion 13 is disposed in the substantially central part, and it is indented in the shape of a substantial square large enough to accommodate a tab 2 of a lead frame 1. On the other hand, a pair of grooves 14 are disposed on a pair of opposite sides of the recessed portion 13 respectively, and they are indented in the shape of a substantial rectangle large enough to accommodate a tab suspending lead 3 of the aforesaid lead frame 1. Just above the right and left grooves 14 in the lower-side pressing member 12, a pair of upper-side pressing members 17 are so provided that they move vertically opposite to the two grooves 14 respectively, and the upper-side pressing members 17 are hook-shaped substantially by using a thin plate material being smaller in thickness than the width of the groove. Moreover, the upper-side pressing members 17 are so formed that the lower end faces thereof abut on the outer peripheral edge portion of the tab 2 in the lead frame 1 and on the lower stage portion of the tab suspending lead 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to bonding technology, particularly to technology for fixedly holding a lead frame as an object to be bonded, such as a semiconductor device (hereinafter referred to as an IC). The present invention relates to a technique that is effective for use in a wire bonding device that electrically connects the leads of a lead frame and a pellet in the manufacture of a lead frame.

[Conventional technology]

As a wire bonding device that bridges the wire between the lead of the lead frame and the electrode of the pellet for electrical connection, the wire is connected to the electrode pad of the pellet and the inner lead of the lead frame while holding the lead frame with upper and lower holding members. There are some that are configured to be bonded to.

An example that describes wire bonding technology is "Electronic Materials November 1981 Special Issue" published by Kogyo Research Association Co., Ltd., published on November 10, 1981, P156-P1.
There is 62.

[Problem that the invention seeks to solve]

However, in such wire bonding equipment, for example, in the case of a tab-hanging lead frame, if the upper and lower pressing members are in contact with the upper surface of the upper part of the tab-hanging lead and the lower surface of the lower part of the tab-hanging lead, the lead frame is held down. , the lead frame is curved and deformed, making it insufficient to hold down the pellet, making it impossible to ensure the flatness of the top surface of the pellet, and as a result of the lead frame moving during bonding, the bonding strength decreases. This was revealed by the present inventor.

An object of the present invention is to provide a bonding technique that can reliably fix a lead frame.

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.

[Means for solving problems]

An overview of typical inventions disclosed in this application is as follows.

That is, the upper pressing member is configured to contact and press the outer peripheral edge of the tab of the lead frame.

[Effect]

According to the above means, the upper presser cooperates with the lower presser to directly hold the tab of the lead frame, so the lead frame is securely fixed, and bonding can be performed properly. Ru.

Embodiment FIG. 1 is an enlarged partial vertical cross-sectional view showing a wire bonding apparatus which is an embodiment of the present invention, FIG. 2 is a plan view taken along line nn in FIG. 1, and FIG. FIG. 4 is a plan view showing the side pressing member, and is a longitudinal cross-sectional view taken along the line ■-■ in FIG. 3.

In this embodiment, this wire bonding apparatus is configured to perform wire bonding to the lead frame 1. The lead frame I is made of a conductive material such as 4270I or copper, and is integrally formed by a suitable means such as punching and press processing, and includes a tab 2 to which a pellet was bonded in the previous process, and a tab. 2
A tab suspension lead 3 that suspends the tab 2, a plurality of inner leads 4 arranged radially surrounding the tab 2, and an outer lead (not shown) that is integrally connected to each of the inner leads 4. ). The tab 2 in this lead frame 1 is lowered by bending the tab suspension lead 3.
The bellet 6 mounted on the tab 2 by lowering the tab
The level difference between the upper surface and the upper surface of the inner lead 4 is eliminated or reduced.

On the other hand, the wire bonding apparatus includes a heat block 11, on which a lower pressing member 12 is removably attached. The lower holding member 12 is formed into a substantially square panel shape using a wear-resistant and thermally conductive material, and has a recess 1 on its upper surface.
3 is disposed approximately in the center and recessed into a substantially square shape large enough to accommodate the tab 2 of the lead frame 1, and a pair of grooves 14 are formed on a pair of opposite sides (hereinafter referred to as left and right) of the recess 13. ), and are recessed in a substantially rectangular shape large enough to accommodate the tab suspension leads 3 of the lead frame 1.

Convex portions 15 are arranged at each of the four corners on the bottom surface of the concave portion 13 in the lower holding member 12, and the convex portions 15 are formed into a substantially square flat plate shape having an outer diameter of about 173 to I/4 with respect to the diameter of the concave portion 13. A matte surface 16 is formed on the upper surface of each convex portion I5 as an uneven surface.

A pair of upper pressing members 17 are provided directly above the left and right grooves 14 in the lower pressing member 12 so as to move up and down while facing both grooves 14, respectively.
is formed into a substantially hook shape in a front view using a plate material thinner than the groove width. The upper pressing member 17 is formed such that its lower end surface abuts against the outer peripheral edge of the tab 2 in the lead frame 1 and the lower portion of the tab hanging lead 3.

An XY table (not shown) is arranged on the outside of the heat block 11 so as to substantially face the lower pressing member 12, and a bonding head (not shown) is placed on this table to move in the XY direction. It is equipped so that it can be used. A bonding arm 21 is supported by the bonding head so as to be able to move up and down, and a bonding tool 22 is disposed at the tip of the arm 21 in a substantially vertical direction and is energized with ultrasonic vibrations. is supported by

A wire 23 made of gold wire or the like is inserted into the bonding tool 22 so as to be able to be drawn out, and the wire 23 is pressed onto the pellet 6 and the inner lead 4 by the bonding tool 22.

Next, the effect will be explained.

In the pre-process, the lead frame 1 with the pellet 6 bonded onto the tab 2 is supplied onto the lower pressing member 12 attached to the heat block 11. At this time, the slightly lowered tab 2 is inserted into the recess 13 recessed in the lower pressing member 12, and the bent tab suspension lead 3 is inserted into the groove 14.

Subsequently, when the upper pressing member 17 is lowered, the lead frame 2 is pressed against the lower pressing member 12 by the upper pressing member 17, and thus is held between them. At this time, the upper pressing member 17 comes into contact with the outer peripheral edge of the tab 2 and the upper surface of the tab hanging door 3, and the lower pressing member 12 has a convex portion 1 that is protruded from the bottom surface of the recessed portion 13.
5 come into contact with the four corners of the upper surface of the tab 2.

Next, the bonding head is
By moving the bonding tool 22 in the direction and raising and lowering the bonding arm 21, the bonding tool 22
are bonded to the electrode pads of the pellet 6 and the inner leads 4 of the lead frame 2, thereby creating a bridge between them and electrically connecting them. At this time, pellet 6
Since the lead frame 2 and the lead frame 2 are heated by the heat block 11, the bonding wire 5 is heated by the ultrasonic vibration energy applied by the bonding tool 22.
The bonding to the pellet 3 and lead 4 will be performed effectively and appropriately.

By the way, if the upper pressing member is configured to press the upper stage of the tab suspension lead 3 than the bent part, the pressing force causes the lead frame 2 to warp and deform, so that the lead frame 2 may move loosely during bonding. The bonding state may become poor due to non-uniform heating by the heat block 11 or improper propagation of ultrasonic vibration energy.

However, in this embodiment, the upper pressing member 17 presses down the outer peripheral edge of the tab 2 and the lower part of the tab suspension lead 3, so that the lead frame 1 is prevented from being warped. Further, since the tab 2 is directly held in cooperation with the lower holding member 12, the lead frame 2 can be securely fixed. As a result, the lead frame 2 is prevented from floating during bonding, the heating by the heat block 11 is not uniform, and the propagation of ultrasonic vibration energy is prevented from becoming inappropriate, so that the bonding is performed in an extremely appropriate manner. It will be held on.

On the other hand, if the bottom surface of the tab 2 is configured so that the bottom surface of the tab 2 contacts the entire flat bottom surface of the concave portion without protruding from the bottom surface of the concave portion of the lower holding member, the tab 2 may be slightly warped or the like. If so, the pressing force of the upper and lower pressing members will act unevenly on the entire tab, which may cause the lead frame 2 to move during bonding, the heating by the heat block 11 to be uneven, or the ultrasonic Improper energy propagation may result in poor bonding conditions.

However, in this embodiment, since the convex portions 15 are provided at the four corners of the bottom surface of the concave portion 13 of the lower pressing member 12,
The convex portion 15 cooperates with the upper holding member 17 to partially hold the tab 2, thereby absorbing or correcting deformation such as warping of the tab 2, and holding the tab 2 with an even gripping force. It turns out.

As a result, the lead frame 2 is prevented from moving during bonding, so that bonding can be performed very properly.

At this time, the contact area of the lower pressing member 12 with the tab 2 is reduced compared to the case of full-surface contact, but since the pear-shaped surface 16 is formed on the upper surface of the convex portion 15, the frictional force does not decrease. .

According to the embodiment described above, the following effects can be obtained.

(1) By configuring the upper pressing member to contact the outer peripheral edge of the tab of the lead frame, the tab can be directly held, so the lead frame can be reliably fixed.

(2) By firmly fixing the lead frame, it prevents the lead frame from moving during bonding, uneven heating by the heat block, and inappropriate propagation of ultrasonic vibration energy. Therefore, an appropriate bonding state can be ensured.

(3) By configuring the upper pressing member to contact the outer peripheral edge of the tab of the lead frame and the tab suspension lead, the lead frame can be fixed more reliably.

(4) By providing protrusions on the bottom of the four parts of the lower holding member, deformation such as warping of the tab can be absorbed or corrected, and the tab can be gripped evenly, making the lead frame even more durable. It can be fixed securely.

(5) By providing an uneven surface such as a satin surface on the convex portion of the lower holding member, the frictional force can be increased, and therefore the gripping force can be increased.

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, the upper pressing member is not limited to being configured to press the outer peripheral edge of the tab and the tab suspension lead, but may be configured to press only the outer peripheral edge of the tab.

The lower pressing member is not limited to be configured to partially press the tab with the convex portion, but may be configured to press the entire tab.

It is not limited to use for fixing tab-down lead frames, but may also be used for fixing ordinary flat lead frames.

The above explanation has mainly been about the application of the invention made by the present inventor to a wire bonding device, which is the background field of application, but the invention is not limited thereto. It can also be used in pellet bonding equipment that performs bonding.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

By configuring the upper pressing member to contact and press the outer peripheral edge of the tab of the lead frame, the tab can be directly held, so the lead frame can be reliably fixed.

[Brief explanation of drawings]

Fig. 1 is an enlarged partial vertical cross-sectional view showing a wire bonding device according to an embodiment of the present invention, Fig. 2 is a plan view taken along the line ■-■ in Fig. 1, and Fig. 3 shows the lower pressing member. The plan view shown in FIG. 4 is IV- of FIG. 3.
It is a longitudinal cross-sectional view along the IV line. DESCRIPTION OF SYMBOLS 1... Lead frame, 2... Tab, 3... Tab suspension lead, 4... Inner lead, 5... Bonding wire, 6... Pellet, 11... Heat block, 12...・・Lower holding member, 13 ・・Recessed portion, 1
4... Groove, 15... Convex portion, 16... Pear surface (uneven surface), 17... Upper holding member, 21... Arm,
22... Bonding tool, 23... Wire. Figure 1 Figure 3 Figure 2 Figure 4

Claims (1)

[Scope of Claims] 1. A bonding device characterized in that an upper pressing member for pressing the lead frame is configured to contact and press the outer peripheral edge of the tab of the lead frame. 2. The bonding device according to claim 1, wherein the upper pressing member is configured to press also a part of the tab hanging lead.