JPH0231844B2 - HANDOTAISOCHORIIDOFUREEMUNOSEIZOHOHO - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a lead frame for a semiconductor device, and in particular, the depth of a break half portion of a suspension lead necessary for cutting off a semiconductor device after resin molding. The present invention relates to a method for manufacturing a lead frame for a semiconductor device, which allows adjustment of lead frames.

(Prior Art) In manufacturing a resin molded semiconductor device, first, as shown in FIG. 7, an island portion 1 for placing a semiconductor pellet, and a skeleton such as a lead connected to the semiconductor pellet by wire bonding are prepared. A lead frame with part 2 is provided.
After partially plating the island portion 1 and the region 4 of the inner lead 3 with metal (gold, silver, etc.), as shown in FIG. 8, semiconductor pellets 5 are bonded onto the plating layer 6 on the island portion 1. Furthermore, the semiconductor pellet 5 and the inner lead are electrically connected by wire bonding. Finally, as shown in FIG. 8, the portion including the semiconductor pellet 5 and the inner lead 3 is sealed with resin 7, and unnecessary frame portions such as the outer reframe portion 8 are cut off to produce a product.

When manufacturing such a lead frame, first, the outer frame portion 8 on both sides of a metal plate for forming a lead frame for a semiconductor device, the island portion 1, and the island whose both ends are supported by the island portion 1 and the outer frame portion 8 are prepared. A lead frame is obtained by masking the portions to remain, such as the lead frame skeleton portion including the supporting hanging lead portion 9 and the inner lead portion 3 disposed around the island portion 1, with a resist layer, and then performing an etching process.

In this case, the outer frame portion 8 of the hanging lead portion 9
In order to facilitate the separation of the resin-sealed semiconductor device from the outer frame portion 8 after resin molding, the connecting portion with the outer frame portion 8 needs to be a thin portion, and this portion is usually connected to the break half portion (indicated by 10 in the figure). show)
This breaking half part 10 is formed at the same time as the lead frame is etched.

In other words, the breaking half part 10 is formed by not applying a resist layer on both sides like other parts, but by applying a resist layer to both sides.
This is done by coating only one side and etching with the other side completely exposed, resulting in the breaking half 10 being thin.

(Problems to be Solved by the Invention) In this way, since the breaking half part 10 is etched at the same time as the other part with one metal surface exposed, the breaking half part 10 is The etching depth is 60 mm of the initial metal material thickness "D" as shown by "d" in Figure 9.
It reaches ~70%. This is because the etching cross-sectional shape and dimensions of the lead frame remain stable even after the metal material is penetrated by etching in other parts of the lead frame (at this time, the etching depth of the break half part 10 is approximately 50%). This is because it is necessary to continue etching further to achieve this.

As described above, if the etching depth of the breaking half part 10 becomes large and the material strength of this part becomes low, problems such as deformation of the island part 1 occur during partial plating in the subsequent process occur. That is, when partially plating the region 4 shown in FIG. 7, the upper mask rubber plate 12 is pressed against the entire back surface of the lead frame 11 as shown in FIG. With the lower mask rubber 13 provided with the opening 13a pressed against it, the plating liquid is sprayed into the opening 11a as shown by the arrow, and only the area 4 is partially plated. In this case, since a pressing force is particularly applied to the upper mask rubber plate 2, the breaking half part 1
If the strength of 0 is too small, this island part 1
may cause deformation.

Therefore, it was necessary to take measures to prevent the strength of the breaking half part 10 from falling below a predetermined level.

(Means for Solving the Problems) The present invention achieves the above-described etching method by providing an etching method capable of appropriately adjusting the etching depth of the break half portion 10 in the etching process of a lead frame for a semiconductor device. This is an attempt to solve the problems of the prior art.

That is, according to the present invention, the island portions on both sides of the metal plate for forming a lead frame for a semiconductor device,
In a method of manufacturing a lead frame for a semiconductor device by selectively applying a resist layer to necessary parts of the lead part, suspension lead part, etc., and then exposing it to an etching solution, By fully masking one side with the above resist layer and etching with the above resist layer partially formed on the other side, the etching speed of that part is slower than other parts, thereby comparing the break half parts. By forming the break half portion shallowly, the strength of the breaking half portion is prevented from becoming less than a predetermined value, thereby solving the above-mentioned problem.

(Specific Description of the Invention) This description will be described below with reference to specific examples shown in the drawings.

Figure 1 shows a metal plate for forming lead frames for semiconductor devices (for example, 42 alloy (42% by weight Ni, balance Fe),
This is a plan view centered on the vicinity of the connecting portion of the suspension lead 21 (phosphor bronze, etc.) with the outer frame portion 22, and shows resist material 25 (hatched portion) on the outer frame portion 22, the lead portion 23, and the suspension lead portion 21. ) is applied. However, the resist material 25 is partially applied (in a grid pattern) to the break half part 21a (the part sandwiched between the broken lines) of the suspension lead part 21, and the resist material 25 is partially applied to the part 21a of the metal plate
is exposed. As is clear from FIG. 2, on the opposite surface of the metal plate, the resist material 5 is applied to the entire suspension lead portion 21 without exposing the metal part 20 as described above. In addition, resist material is naturally applied over the entire surface of the outer frame portion 22 and lead portion 23 on the opposite side.

When the lead frame forming metal plate is etched from both upper and lower surfaces using an etching solution in this state, the etching of the exposed metal portion 26 to which no resist material 25 is applied proceeds as usual, but the break half portion 21a Since the resist material 25 is partially present on one side, the etching speed is slow, and as shown in FIG. 21a is only slightly etched. When etching is continued to adjust the etching cross-sectional shape and dimensions of the lead frame, the break half part 2 is
The resist material 25 of 1a is automatically removed, and finally, as shown in FIG.
The etching depth "d" of 1a can be suppressed to 50% or less of the original thickness of the metal plate. FIG. 4 shows the cross-sectional shape of the suspension lead 21 obtained by such an etching method when viewed from the side.

Generally, the etching depth of the breaking half part 21a can be arbitrarily adjusted by adjusting the roughness, shape, etc. of the pattern of the resist material applied to one surface of the breaking half part 21a. However, in general, by forming a resist pattern with a line width and spacing (portion where no resist is applied) of 1/3 to 1/10 of the thickness of the metal plate, the etching depth of the break half part 21a can be increased. It is preferable to set the thickness to about 30 to 50% of the original plate thickness.

Figures 5 and 6 show the break half part 21.
The first modification of the resist pattern formed in a
The one shown in FIG. 5 corresponds to the figure, and for example, when a 50 μm square resist 25a is formed in a dot pattern with a 50 μm gap on a metal plate having a thickness of 130 to 30 μm, The figures also show the case where a resist 25b with an annular pattern is applied to a metal plate having a thickness of 130 to 300 μm with a line width of 30 μm and a gap of 30 μm. Note that the shape of the resist pattern is naturally not limited to the above example, and any shape can be selected.

(Example) A 250 μm thick metal plate made of 42 alloy was prepared as a metal plate for forming a lead frame for a semiconductor device.
Both sides of this metal plate are coated with polyvinyl alcohol-based photosensitive resin (polyvinyl alcohol 0% by weight,
K ₂ Cr ₂ O ₇ 1% by weight, water 89% by weight) is applied as a resist material, and then the first
A lattice resist pattern as shown in the figure and FIG. 2 was formed. In other words, the break half part has an opening dimension (a x b) of 80 μm x 60 μm,
A lattice pattern was formed in which the interval c between the openings was 40 μm.

Next, the metal plate with this resist pattern is etched with an etching solution at a temperature of 50 to 70°C (38 to 42 baud).
Etching treatment was performed using FeCl ₃ solution (hydrochloric acid 0.2%) for 10 to 15 minutes. As a result, a lead frame with a predetermined shape was formed, and the thickness of the break half part was approximately 50 μm (etching depth = approximately 40 μm of the original metal plate).
%).

(Effects of the Invention) As described in detail above, according to the present invention, the etching depth of the break half portion can be controlled arbitrarily by adjusting the etching speed of the break half portion, so that the strength of the break half portion can be sufficiently increased. Therefore, it is possible to completely prevent the generation of defective products due to deformation of the island portion during the partial plating process of the island portion and the inner lead portion. Further, according to the method of the present invention, the etching depth of the break half portion can be adjusted simultaneously in the same process as the conventional method without adding a special process, so that the process does not become complicated.

[Brief explanation of drawings]

FIG. 1 is a plan view for explaining the method of manufacturing a lead frame for a semiconductor device according to the present invention, and is a diagram mainly showing the break half part, and FIGS. 2 and 3 are the same as those shown in FIG. A cross-sectional view showing the progress of etching along the line A-A, FIG. 4 is a cross-sectional view showing the state of the hanging lead after the etching process, and FIGS. 5 and 6 show the resist pattern in the break half part. 7 is a plan view showing a modification example corresponding to the one in FIG.
Fig. 8 is a plan view showing a part of a lead frame for a semiconductor device, and Fig. 8 is a cross-sectional view showing a state in which the semiconductor device is sealed with resin on the lead frame, and corresponds to line B-B in Fig. 7. Figure 9 is a diagram illustrating the etching depth of the break half part.
FIG. 0 is a sectional view showing a state in which a lead frame is partially plated. In the figure, 1... island part, 2... skeleton part,
3... Inner lead, 4... Region, 5... Semiconductor pellet, 6... Plating layer, 7... Resin, 8...
...Outer frame part, 9...Hanging lead part, 10...
... Half part for break, 11 ... Lead frame, 11a ... Opening, 12 ... Upper mask rubber plate, 13 ... Lower mask rubber plate, 13a ... Opening, 21 ... Hanging lead, 21a ... Half for break 22...outer frame part, 23...lead part, 25...resist material, 26...metal exposed part.

Claims (1)

[Scope of Claims] 1. An outer frame portion on both sides of a metal plate for forming a lead frame for a semiconductor device, an island portion for mounting a semiconductor element, and a hanger for supporting the island portion whose both ends are supported by the island portion and the outer frame portion. In the method for manufacturing a lead frame for a semiconductor device, the lead frame skeleton including the lead portion and the inner lead portion disposed around the island portion is masked with a resist and then subjected to etching treatment, wherein the upper outer frame of the hanging lead is etched. One side of the area where the break half part is to be formed near the connecting part with the part is fully masked with the resist, and the other side is etched with the resist partially masked, and the etching speed of this partially masked part is determined. A manufacturing method characterized in that a breaking half part is formed by delaying the breaking part later than other parts. 2. On the other surface of the part where the break half of the suspension lead is planned to be formed, there is a
Claim 1, characterized in that a resist pattern having a line width and a spacing of 1/3 to 1/10 is formed and then etched to form a break half part. Production method. 3. The manufacturing method according to claim 1, wherein the etching depth of the breaking half part is set to 30 to 50% of the thickness of the metal plate by adjusting the etching speed of the breaking half part.