JPS63107124A - Manufacture of semiconductor device and molding die used therein - Google Patents

Abstract

PURPOSE:To facilitate removal of dam burr yielded in the inside of a dam and to ensure the removal, by forming resin burr yielded by molding so that the central part is thick and mechanical strength is large with respect to the boundary part between a lead frame part and a package. CONSTITUTION:When a semiconductor device is manufactured by using a lead frame 1, a thin region 18, whose thickness is the same as that of the lead frame 1, consists of the following parts of dam burr 7 yielded in resin molding in the lead frame 1: leads 3; an outer frame 5; the boundary parts with dams 6; and the boundary part with a package 2 formed by resin molding. The inner central part of the region 18 is formed as a thin protruding part 19. When an external force is applied to the dam burr at the time of removal of the dam burr, stress is concentrated on the end of the thin region 18, i.e., the leads 3, the outer frame 5, the lead frame part of the dam 6 and the boundary surface with the package 2. Thus the dam burr 7 is cut and separated from the interface without the remaining part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device and a mold used in the method.

[Conventional technology]

2. Description of the Related Art Resin-molded semiconductor devices (also referred to as semiconductor devices) use a substrate formed by patterning a metal plate called a lead frame.

In manufacturing a resin molded semiconductor device, first, a chip (half-quad element) is fixed (chip bonding) to the chip mounting part of this lead frame, and each electrode of this chip and each electrode of the lead frame are The inner ends of the leads are electrically connected (wire bonding) with wires. Thereafter, the chip and the molded areas such as the inner ends of the leads are molded (sealed) with resin, and the chip and the like are covered with a package made of resin. Further, unnecessary portions of the lead frame are cut and removed to produce a resin molded semiconductor device. Further, after the unnecessary lead frame is removed, the leads protruding from the package are molded, for example, into an in-line type, if necessary.

A transfer mold press is generally used for the sealing. In this semiconductor device, as mentioned above,
After the lead frame with the chip mounted and wire tensioned is sandwiched between the upper and lower parts of the mold (mold clamping),
The resin tablet placed in the pot in the center of the upper mold and placed on the cull in the center of the lower mold is heated under pressure with a plunger to melt it, and the melted resin is passed through the resin flow path (main runner) formed by the upper and lower molds. , sub-runner, and gate) into the cavity, and the lead frame portion located inside the cavity is covered with resin. Further, since the resin in the cavity and the resin flow path is cured and hardened, the cured molded product is taken out after the upper mold and lower mold are separated (mold opening).

In this type of transfer mold press, resin burrs such as lead flash occur during resin molding.
These particles are removed after resin molding. For example, see “Electronic Materials 419” published by Kogyo Research Council.
1981 special issue, published November 10, 1981, P170
- P175 states that after molding, surface treatment is performed to ensure solderability of the outer leads of the IC, but as a pretreatment, lead flash generated during molding must be removed in advance. ing. The same document also mentions the mechanical blasting method and the chemical treatment method using chemicals as deflashing methods for removing this paris, and in order to maintain quality, particles (media) such as glass beads, alumina, and polystyrene are used. It is stated that the dry blasting method, in which particles are sprayed with high-pressure air, and the wet blasting method, in which particles are mixed with a solvent such as water, are widely used.

Further, although the following is not a publicly known technique, it is a resin burr removal technique studied by the present inventor, and its outline is as follows.

That is, resin burrs include flashes that occur on the surface of the lead frame and dam burrs that occur inside the dam.

These resin burrs are removed by the deflashing method described above. As a method for removing the dam burr, the present applicant uses a mold to punch out the resin burr with a press.

FIG. 9 shows the lead frame 1 after molding in the manufacture of semiconductor devices. As shown in the same figure, the package 2 made of resin formed by molding is arranged on the inner end side of the lead 3 and on the tab hanging lead 4.
The inner end side is sealed. Generally, when the lead frame 1 is clamped with the upper and lower molds, the front and back surfaces of the lead frame 1 are in close contact with the parting surfaces of the upper and lower molds, but the gaps in the pattern are the same as the thickness of the lead frame 1. occurs. Therefore, during molding, resin flows into the gap that communicates with the cavity. This inflowing resin actually flows into a pair of facing outer frames 5 of the lead frame 1 extending outside the cavity, and a pair of facing dams extending from these outer frames 5 and connecting each lead 3. It is first obstructed by the endless frame formed by 6. In the figure, a resin burr, ie, a dam barrier, formed by the curing of this inflowing resin is shown by crosshatching.

Therefore, in order to remove these dam barriers, the 10th
As shown in the figure, a punch 9 having a comb-shaped punching blade 8
By punching out the dam barrier that exists between the three reeds, it is used as a bush.

[Problem that the invention seeks to solve]

The present inventor has revealed that the method of directly punching out the dam barrier for removing the dam barrier is often undesirable due to the following points.

The punching blade 8 of the punch 9 has a width narrower than the interval between the leads 3 so as not to punch out the lead 3 portion during punching. For this reason, when the dam barrier is punched out with the punching blade 8, the surrounding portion of the dam barrier tends to remain as shown in FIG. 11. Since this residual dam burr 10 is thin and only slightly attached, it is difficult to remove it afterwards. This residual dam burr 10 impairs the soldering of the leads 3.

Further, the residual dam burr 10 also becomes an unstable burr 11 in an unstable state that is partially connected to the package 2, as shown in FIG.

The residual dam burrs 10 and unstable burrs 11 as described above are likely to fall. Fallen burrs can mesh with the sliding parts of various parts of the manufacturing equipment, causing problems with the driving of the manufacturing equipment, or, when the lead is being cut and formed, it can rest on the lead and be pressed, resulting in resin dents on the lead surface. This may cause poor appearance.

An object of the present invention is to provide a method for manufacturing a semiconductor device that can reliably remove dam burrs that occur inside a dam.

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

[Means for solving problems]

A brief summary of typical inventions disclosed in this application is as follows.

That is, in the method for manufacturing a semiconductor device of the present invention, a recess is provided in the parting surface of the mold corresponding to the area where resin burrs occur inside the dam of the lead frame and the outer frame, so that the resin burr generated by the mold can be prevented. In some cases, the resin burr is formed to be thicker at the center than at the periphery, so that the resin burr is easily separated from the lead frame portion and the package when removing the resin burr. Moreover, the resin burr is
Since the surface protrudes from one surface of the lead frame, by rolling the roller and pushing down the resin burr protruding from the lead frame surface, the resin burr is separated from the lead frame portion and the package.

[Effect]

According to the above-mentioned method, the resin burr generated by molding is thicker in the center and has greater mechanical strength than the boundary between the lead frame and the package, so when an external force is applied to the resin burr, the resin burr is removed. Good separation from lead frame parts and packages without leaving any residual parts. In addition, since resin burrs can be removed simply by pushing down the resin burrs protruding from the lead frame surface, the resin burrs can be reliably separated by pushing down due to rolling contact of the rollers, instead of using a comb-shaped punch that is expensive and easily damaged. is no longer necessary, reducing equipment costs.

〔Example〕

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

FIG. 1 is a flowchart showing a method for manufacturing a semiconductor device according to an embodiment of the present invention, FIG. 2 is a plan view of a lead frame subjected to chimp bonding and wire bonding, and FIG. 3 is a lead frame after molding. FIG. 4 is a perspective view showing a part of the mold, FIG. 5 is a sectional view showing the dam burr, and FIG.
The figure is also a cross-sectional view showing the state in which the dam burr is removed.
The figure is also a front view showing the semiconductor device in a completed state.

As shown in the flowchart of FIG. 1, a semiconductor device is manufactured through the following steps: lead frame preparation, chip bonding, wire bonding, molding, resin burr removal, and cutting.

A lead frame 1 used for manufacturing semiconductor devices has a pattern as shown in FIG. 2, for example. The lead frame 1 includes a pair of parallel outer frames 5 and a thin inner frame 12 that connects the outer frames 5 at predetermined intervals.
, a plurality of cantilever-structured leads 3 extending parallel to the outer frame 5 from the inner edges of the pair of inner frames 12 facing each other, and a plurality of leads 3 extending parallel to the inner frame 12 at the ends. 3, an outer frame 5, and a dam 6 that connects each lead 3. Further, a rectangular tab 13 is provided at the center of the lead frame pattern formed by the outer frame 5 and the inner frame 12. This tab 13 is supported at both ends by a thin tab suspension lead 4 whose one end is connected to the outer frame 5.

On the other hand, the portion of the lead 3 outside the dam 6, that is,
The outer leads 14 are arranged at equal intervals and extend parallel to each other, but the parts of the leads 3 inside the dam 6, that is, the inner leads 15, are parallel to each other up to the middle. However, its tip is connected to the tab 1 mentioned above.
It extends and bends towards 3.

When manufacturing a semiconductor device using such a lead frame 1, chip bonding is first performed, and a semiconductor element (chip) 16 is placed on the tab 13 as shown by a dashed line in FIG. Bonded.

Next, wire bonding is performed, and the chip 16
The electrodes and the inner ends of the leads 3 corresponding to these electrodes are connected by wires 17.

Next, resin molding is done. This mold is
As shown in FIG. 2, this is performed on the area surrounded by the outer frame 5 and dam 6 of the lead frame 1, that is, the area surrounded by the two-dot chain line. As a result, as shown in FIG. 3, the chip 16. The inner end portions of the wire 17 and the lead 3 are covered. At this time, resin is embedded in the area surrounded by the lead 3 and the dam 6, the area surrounded by the tab suspension lead 4, the dam 6, and the outer frame 5, as shown by the hatching in FIG. In other words, a dam barrier will occur.

Moreover, this is a characteristic feature of the present invention, but the dam barrier generated by the mold is
part, i.e. lead 3. As shown in FIG. 5, the boundary between the outer frame 5° and the dam 6 and the boundary between the resin molded package 2 and the lead frame 1 form a thin region 18 having the same thickness as the lead frame 1. However, since the inner center portion is formed as a thick protrusion 19, when an external force is applied to the dam barrier during removal of the dam barrier, the end of the thin region 18, that is, the lead 3. Outer frame 5. Stress concentration acts on the interface between the lead frame portion of the dam 6 and the package 2, and the dam barrier is separated from the interface without leaving any residual parts.

In this way, there is a mesa-shaped protrusion 19 in the center of one side of the dam barrier.
In order to form this part, it is necessary to provide a recess into which the resin flows on the parting surface of the mold corresponding to this part. For example, as shown in FIG. 4, in this embodiment, the recess 20 is provided on the parting surface 22 that comes into close contact with the upper mold of the lower mold (mold mold) 21. As shown in the figure, nine rectangular cavities 23 are provided on the parting surface 22 of the lower mold 21. As shown in FIG. This cavity 23 is configured to form a mold space for forming the package 2 together with the cavity of the upper mold when it is brought into close contact with the upper mold.

Furthermore, a gate 24 through which resin is fed is provided at one end of the cavity 23. A depression 20 is provided around the cavity 23 corresponding to a portion where a dam barrier is formed. As shown in FIG. 4, this depression 20 is specifically provided facing the area between the leads and the area between the leads and the tab lead. Further, the circumferential wall of the recess 20 is inclined in a dish-like manner. Therefore, the mold releasability is also good. Such a lower mold 21
As a result of using the dam barrier, as shown in FIG.
8.

Next, resin burrs are removed, ie, the dam barrier is removed. In this embodiment, as mentioned above, since the protrusion 19 of the dam barrier protrudes beyond the surface of the lead frame 1, the protrusion 19 can be removed without preparing a comb-shaped punch to push down only the dam barrier portion. The dam barrier is reliably separated from the lead frame portion and the package 2 by simply pressing the surface down to the surface of the lead frame 1.

Therefore, in this embodiment, as shown in FIG. 6, the lead frame 1 having the package 2 is turned over and placed on the table 25, and
The protrusion 19 of the dam barrier is pushed down while the roller 26 is moved, and the dam barrier is removed by this pushing down. The table 25 has a hole into which the package 2 part is inserted, so that no external force is applied to the package 2 when the dam barrier is removed. Further, this table 25 is provided with a large number of punch holes 27. This extraction hole 27 faces the dam barrier of the lead frame 1 to be placed, and when the dam barrier is pushed down, the dam barrier separated from the lead frame portion and the pan cage 2 can pass through and fall without being caught. There is.

Next, by cutting and forming with a press, a dual in-line type semiconductor device 2 is formed as shown in FIG.
8 is produced.

According to such an embodiment, the following effects can be obtained.

(1) According to the present invention, resin burrs formed between leads, dams, etc. that occur during molding are thick at the center and thin at the periphery, which is the same thickness as the lead frame. When removing the resin burr, stress concentration acts between the periphery of the resin burr and the lead frame portion, and the resin burr as a whole has high mechanical strength, so that the resin burr can be removed without remaining.

(2) According to (1) above, according to the present invention, no resin burrs remain on the lead frame part after molding, so lead soldering caused by residual resin burrs does not cause defects in quality and improves quality. Effects can be obtained.

(3) According to the above (1), according to the present invention, there is no resin burr remaining in the lead frame portion, so there is no resin burr falling off from the lead frame in the subsequent process, and the manufacturing device This has the effect that driving defects can be prevented.

(4) According to the above (1), according to the present invention, since no resin burrs remain on the lead frame portion, there is no possibility that the resin burrs will fall off from the lead frame in the subsequent process, and the resin burrs placed on the leads can be removed. As a result of pressing together, defects such as indentation on the lead surface do not occur, and the effect of reducing the incidence of appearance defects is achieved.

(5) According to the present invention, in order to facilitate the removal of resin burrs, depressions are provided in the mold corresponding to resin burr occurrence areas, but these depressions are also spaces through which voids generated within the cavity can escape. As a result, voids do not remain in the pan cage, and the reliability of semiconductor device sealing is increased.

(6) According to the above (1) to (5), according to the present invention, a synergistic effect is obtained in that semiconductor devices of excellent quality can be manufactured at low cost.

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 above Examples and can be modified in various ways without departing from the gist thereof. For example, as shown in FIG. 8, in order to remove a resin burr, that is, a dam barrier, it is sufficient to push down the protrusion 19 of the dam barrier to the surface of the lead frame 1. The dam barrier is removed by pushing down the dam barrier with a punch 29. In this embodiment, the punch 29 has a planar structure with a flat pressing surface, so the manufacturing cost of the punch 29 is reduced. Further, since the punch 29 has high mechanical strength, according to this embodiment, the equipment cost is reduced, and as a result, the manufacturing cost of the half-body device can be reduced.

In the above description, the invention made by the present inventor is mainly applied to the manufacturing technology of semiconductor devices, which is the background field of application, but the invention is not limited thereto.

The present invention can be applied to molding techniques where resin burrs occur.

〔Effect of the invention〕

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

According to the present invention, the mold is provided with a recess into which the resin flows into the parting surface so that the resin burr is thicker at the center than the periphery. By applying an external force, the lead frame portion and the package are reliably separated at the interface without leaving any residual portions.

As a result, the adverse effects caused by residual resin burrs are eliminated.

In addition, resin burrs can be reliably removed by simply pushing the resin burrs protruding from the lead frame surface down to the lead frame surface, so resin burrs can be removed by rolling contact with rollers or simply pressing with a block-shaped punch.
Equipment costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing a method for manufacturing a semiconductor device according to an embodiment of the present invention, FIG. 2 is a plan view of a lead frame subjected to chip bonding and wire bonding, and FIG. 3 is a lead frame after molding. 4 is a perspective view showing a part of the mold, FIG. 5 is a sectional view showing the dam burr, FIG. 6 is a sectional view showing the dam burr being removed, and FIG. 7 is a sectional view showing the dam burr removed. FIG. 8 is a cross-sectional view showing a method for removing dam burrs according to another embodiment of the present invention; FIG. 9 is a schematic plan view showing a part of the state in which dam burrs are generated; FIG. , Fig. 10 is a cross-sectional view showing the dam burr removal method by the present applicant, Fig. 11 is a schematic diagram showing the remaining state of dam burrs, and Fig. 12 is a schematic diagram showing other remaining states of dam burrs. Lead, 4... Tab hanging lead, 5... Outer frame, 6... Dam, 7... Dam burr, 8... Punching blade, 9... Punch, 10... Residual dam burr, 11...
・Unstable burr, 12...Inner frame, 13...Tab, 14
...Outer lead, 15...Inner lead, 1
6... Chip, 17... Wire, 18... Thin page area, 19... Protrusion, 20... Hollow, 21... Lower die, 22... Parting surface, 23 ...Cavity, 24...Gate, 25...Table, 26...
Roller, 27...Drilling hole, 28...Half oO Fig. 5 Fig. 7 Fig. 2r-claw/〉b

Claims (1)

[Claims] 1. A step of preparing a lead frame on which chip bonding and wire bonding have been completed, and molding the inner region of the dam of the lead frame with resin, and molding the inner ends of the chip, wire, and lead with a resin package. and a step of removing resin burrs on the inside of the dam caused by the molding, and during the molding, the resin burr surface is formed so as to be thick so as to protrude from at least a part of the surface of the lead frame. and then removing the resin burr by pushing out the resin burr with a pressing body that reaches the surface of the lead frame. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the resin burr is formed thin at a border between the lead frame and the package. 3. A mold for packaging an inner region of a dam of a lead frame on which chip bonding and wire bonding have been completed with resin, wherein at least a portion of the main surface of the mold corresponding to the inner region of the dam where resin burrs are generated by the mold is packaged with resin. A mold type characterized by being provided with a depression that is filled with resin.