JPH0139213B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lead frame holding device for a wire bonding apparatus, and particularly to a lead frame holding device suitable for a lead frame in which a pellet mounting portion is displaced below the lead portion.

FIGS. 1a and 1b show an example of a lead frame to which the present invention is applied. The lead frame 10 includes an outer frame portion 11, a pellet attachment portion 12 to which pellets 15 are attached, and an island frame portion 13 that connects the pellet attachment portion 12 to the outer frame portion 11.
and a lead portion 14 extending closer to the pellet attachment portion 12 than the outer frame portion 11, and the pellet attachment portion 12 is formed to be displaced downward by h from the lead portion 14.

FIG. 2 shows a conventional lead frame holding device for fixing the lead frame 10 in order to apply wire bonding to the lead frame 10. In FIG. 2, a is a plan view, b is a front view, and FIG. 3 is a sectional view taken along line 3-3 of FIG. 2a. A sample stand 21 with a built-in cartridge heater 20 is attached to a mounting stand 22.
The upper surface of the sample stage 21 includes a guide surface 21a that guides the outer frame portion 11 and the lead portion 14 of the lead frame 10, and a pellet attachment portion 12.
A concave portion 21 is recessed by the guide surface 21a by the amount of displacement h of the pellet mounting portion 12 so as to guide the pellet mounting portion 12.
b is formed. The sample stage 21 has a bonding work window 23 necessary for bonding work.
The cover 23 on which a is formed is connected to the guide surface 21.
a, it is fixed so as to cover the recess 21b. Also, in the bonding work window 23a, there is a holding portion 2 of a holding plate 24 which is moved up and down by a vertical drive mechanism (not shown).
4a is inserted, and the lead frame 10 is held down and clamped by this holding part 24a. A bonding head 25 that is driven in the X and Y directions is disposed on the side of the sample stage 21, and a bonding arm 26 is attached to the bonding head 25 so as to be movable up and down. A bonding tool 27 is provided at one end of the bonding arm 26 for wire bonding the pellet 15 and the lead portion 14 through the bonding work window 23a.
is fixed.

Next, the operation of this device will be explained. First, with the presser plate 24 raised, the lead frame 10
Unless shown, the pellets are fed by a feeding mechanism so that the first pellet portion 15a is positioned at the bonding portion. Next, the presser plate 24 is lowered, and the presser part 24
a to press the lead portion 14 and the island frame portion 13 against the guide surface 21a, and clamp the lead frame 10. In this state, the bonding head 25 operates, and the bonding tool 27 releases the pellet 1 in the first pellet portion 15a.
A wire (not shown) is bonded to the lead portion 14 and the lead portion 14 . Next, the bonding head 25
The bonding tool 27 is positioned above the second pellet portion 15b and bonded in the same manner. When this operation is repeated and the bonding of the plurality of pellet parts 15a, 15b, 15c, etc. is completed, the presser plate 24 is raised and the lead frame 10 is fed by the number of pellets for which bonding has been completed. At the same time, the bonding head 25 returns to its original starting position.

By the way, the amount of displacement h of the pellet mounting portion 12 shown in FIG. 1 has some variation due to processing. Therefore, considering the state in which the lead frame 10 is clamped by the holding plate 24 as described above, if the displacement h is small due to the step between the guide surface 21a and the recess 21b, the lead frame 10 is clamped as shown in FIG. 3a. Although the part 14 is pressed down, the pellet attachment part 1
A gap is created between the lower surface of the pellet 2 and the recess 21b, and the pellet mounting portion 12 cannot be held down. On the other hand, if the displacement h is larger than the level difference between the guide surface 21a and the recess 21b, the pellet attachment part 12 will come into close contact with the recess 21b, as shown in FIGS. However, presser plate 2
4 hits the island frame part 13 and does not descend any further, so the lead part 14 and the guide surface 21
A gap is created between the lead part 14 and the lead part 14. As described above, in the past, only either the lead portion 14 or the pellet attachment portion 12 could be securely pressed, which resulted in the disadvantage that bonding failure or bonding position shift occurred.

Furthermore, since burrs and warpage may occur near the tip of the lead portion 14 during press punching during lead frame production, in the case of FIG.
, the other parts are lifted up, and the lead part 14
The clamped state is extremely unstable. Furthermore, since the lead portion 14 is supported at one time,
In the case of Fig. 3a, if the material has a high coefficient of thermal expansion such as a copper lead frame, the guide surface 21a
A temperature difference occurs between the surface that is in close contact with the surface and the surface that is not,
As shown in FIG. 5, the tip of the lead portion 14 is separated from the guide surface 21a, and the lead portion 14 is
cannot be clamped.

The present invention was made in view of the drawbacks of the prior art described above, and an object of the present invention is to provide a lead frame holding device that can reliably clamp a lead frame.

Hereinafter, the present invention will be explained with reference to illustrated embodiments.

FIG. 6 is a plan view showing an embodiment of the lead frame holding device according to the present invention, and FIG.
7 line cross section is shown, a is a state diagram when the presser plate is raised,
8b is a state diagram when the presser plate is lowered, and FIG. 8 is a sectional view taken along line 8-8 of FIG. 7b. Note that the same members or equivalent parts as in FIGS. 2 and 3 are designated by the same reference numerals, and their explanations will be omitted.

A slit 24b is formed in the holding portion 24a of the holding plate 24 for each device of the lead frame 10 to provide some springiness. Also, the presser part 24a
As is clear from FIG. 8, a relief portion 24c is formed on the lower surface of the frame 24 at a portion corresponding to the island frame portion 13. In the sample stage 21, the depth of the recess 21b from the guide surface 21a is formed to be slightly shallower than the displacement h of the pellet mounting section 12 shown in FIG.
A recess 21c is formed in the portion.

In this way, the depth of the recess 21b is formed to be slightly shallower than the displacement h of the pellet mounting part 12, so that the lead frame 10 has the lower surface of the pellet mounting part 12 always in close contact with the recess 21b, and the lead part 14 and the guide A gap exists between the surface 21a and the surface 21a.
However, as described above, since the relief part 24c is formed on the lower surface of the holding part 24a so that it does not hit the island frame part 13, only the lead part 14 supported in a cantilevered manner is exposed to the holding part 24a.
The lead portion 14 can be reliably brought into contact with the guide surface 21a. In addition, a recess 21c is formed on the guide surface 21a corresponding to the presser part 24a.
9, the lead portion 14 is not only pressed against the guide surface 21a, but also deforms within the elastic limit of the lead portion 14 itself and comes into close contact with the guide surface 21a, as shown in FIG. This eliminates the instability of holding down the lead portion due to burrs existing at the tip of the lead portion 14 and the lifting of the lead portion tip due to large thermal expansion as in the case of a copper lead frame. When the lead part 14 is pressed in this way, the tip of the lead part 14 will always be on the guide surface 21a.
Although it will float a little more, the amount of floating will be uniform with no variation, so there will be no hindrance to the bonding work, and this will be in a rather preferable state.

In the above embodiment, the case where the holding plate 24 moves up and down has been described, but the holding plate 24 may be fixed and the sample stage 21 may move up and down, or both may move up and down. .

As is clear from the above description, according to the present invention, the pellet attachment part and the lead part are reliably pressed against the sample stage, so that good bonding can be performed.

[Brief explanation of drawings]

Figure 1 shows the lead frame, a is a plan view,
b shows a sectional view taken along the line 1b-1b of a, FIG. 2 shows a conventional lead frame holding device, a shows a plan view, b shows a front view, and FIG. 3 shows a sectional view taken along the line 3-3 of FIG. 2a. , a is an explanatory diagram when there is a gap between the pellet attachment part and the recessed part of the sample stage, b is an explanatory diagram when there is a gap between the lead part and the guide surface of the sample stage, and FIG. 4 is as shown in FIG. Fig. 5 is an explanatory diagram of the deformed state of the tip of the lead portion; Fig. 6 is a plan view showing an embodiment of the lead frame holding device according to the present invention;
Figure 7 shows a cross section taken along line 7-7 in Figure 6, a shows a state in which the presser plate is raised, b shows a state in which the presser plate descends, and Figure 8 shows a cross section taken in line 8-8 in Fig. 7b. FIG. 9 is an enlarged view of the main part of FIG. 7b. 10...Lead frame, 12...Pellet attachment part, 14...Lead part, 21...Sample stand, 21
a... Guide surface, 21b... Recess, 21c... Recess, 24... Holding plate, 24a... Holding part, 24a
...Slit.

Claims (1)

[Scope of Claims] 1. A sample stand on which a lead frame is placed, which is displaced downward from the lead part and has a pellet attachment part formed thereon; a lead frame having a presser plate fixed to a sample stage, the upper surface of the sample stage having a guide surface for guiding the lead section, and a recess recessed from the guide surface for guiding the pellet mounting section; In the lead frame holding device, the depth of the recessed portion from the guide surface is formed to be shallower than the amount of displacement of the pellet mounting portion, and the holding portion of the holding plate is formed to press only the lead portion. . 2. The lead frame holding device according to claim 1, wherein a recess is formed in the guide surface of the sample stage at a portion corresponding to the holding part of the holding plate. 3. The lead frame holding device according to claim 1, wherein a slit is formed in the holding portion of the holding plate for each device of the lead frame.