JPH07153884A - Resin molded integrated semiconductor device and manufacture of the same and manufacturing apparatus - Google Patents

Abstract

PURPOSE:To control generation of dross at the time of cutting a lead frame with a laser beam by cutting a dam bar of the solder-plated lead frame with a laser beam after the resin molding. CONSTITUTION:When a metal material of lead frame 2 is solder-plated and a dam bar 3 is cut by the laser beam 9, an alloy 5 of solder and lead frame metal formed between the solder which is once fused and diffuses to the lower surface due to the influence of gravity and the lead frame metal is deposited as a layer at the lower surface of the lead frame 2. In this case, since the alloy 5 of solder and lead frame metal is very wettable with respect to the lead frame 2, it does not drop as the liquid to the lower side, extends in the lateral direction as the layer and fuses strongly to the lead frame 2. Therefore, formation of dross 4 which has been generated at the time of cutting the dam bar and/or lead frame external circumference with a laser beam can be controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-molded integrated semiconductor device, its manufacturing method, and its manufacturing apparatus.

[0002]

2. Description of the Related Art In recent years, the progress of packaging technology for integrated semiconductor devices has been remarkable, and high-density packaging has been carried out in various products. For mounting on a substrate, a semiconductor IC chip integrated through various steps is mounted on a system in which a plurality of leads for external wiring, which are so-called lead frames, are projected in parallel at a constant interval to the outside, and are mounted to the outside. The metal terminals (leads) are to be wired. The packaged integrated semiconductor device is resin-molded for circuit protection.
At this time, the liquid resin injected into the cavity of the molding die flows outward when the cavity is filled, and collects in a gap between metal leads for external wiring, that is, a so-called dam.

FIG. 3 is a top view showing a schematic structure of a fine frame called QFP type. 7 is a semiconductor device molded with resin, and 11 is a dam. To prevent the highly fluid resin from flowing further outward,
A dam bar 3 is provided by connecting the metal leads at right angles. Dam bars are also called tie bars. Dam bar 3
Serves to prevent the resin from flowing out to the outer lead 6 side, and also serves to reinforce the mechanical strength of the lead frame during processing. After the molding resin is solidified, the dam bar 3 is no longer necessary, and is cut and removed, so that the metal leads are electrically independent.

As a method for removing the dam bar 3, a press punching method as described in JP-A-63-31128 and a laser beam cutting method as described in JP-A-3-294077 have been put into practical use. ing.

Removal of the dam bar 3 usually involves removal of the resin that has flowed into the dam 11 and solidified. This is because if the solidified resin is left unattended, the leads may be damaged in the subsequent process, or the adhered metal strips may fall, causing troubles.

In a lead frame having a high packaging density in recent years, the pitch width of the outer leads 6 has become very narrow, and the width of the outer leads 6 itself has become narrow. In particular,
Fine lead frames with a lead pitch width of 0.5 mm or less are often used. Also, compared to the type in which the leads are projected in two directions from the resin molding package, a type that enables higher density mounting, that is, 4 types from the package.
QFP (quadrate f) with leads protruding in the direction
A lat package type frame is often used.

For the treatment of the above-mentioned lead portion of the resin mold integrated semiconductor device having such a fine and complicated structure, the laser cutting method is usually used instead of the press punching method.

[0008]

When the dam bar 3 and the outer peripheral lead frame (region A surrounded by the dotted line in FIG. 3) are cut, the press punching method causes less trouble to be carried over to the subsequent process. However, it cannot be applied to the resin-molded semiconductor device mounted with high density as described above because of the problem of accuracy.

The cutting method using a laser beam is to irradiate a laser beam focused with a lens system at a high density to melt and cut metal and resin. For this reason, the metal at the cut point is locally melted and then solidified again on the lower surface of the lead frame. A 42 alloy (iron / nickel alloy) or a copper alloy is generally used as the metal material forming the lead frame.

When these metals are locally melted by a laser beam and then re-solidified, a dross 4 is usually formed as shown in the cross section of FIG. 5 (B). As shown in the figure, the dross 4 is an oxide that generally has a small contact area with the lead frame and is fragile, so that there is a possibility that it may peel off or fall off during the subsequent transportation process or the next manufacturing process. Is high. The dropped dross 4 is caught in a movable part during the transportation process and causes a failure, or is reattached to the back surface of the semiconductor device to cause a trouble during positioning of processing, or a short circuit occurs between leads of a printed circuit board to cause a circuit malfunction. It may cause a short accident.

An object of the present invention is to provide a semiconductor device, a method of manufacturing the same, and a manufacturing apparatus in which the generation of dross when the laser beam of the lead frame is cut is suppressed.

[0012]

In order to achieve the above object, the present invention discloses a resin mold integrated semiconductor device in which a dam bar is laser-cut after a solder plating process. Further, the present invention discloses a resin mold integrated semiconductor device in which a dam bar is laser-cut and a peripheral lead frame is laser-cut after solder plating.

Further, in the present invention, in the above laser cutting process,
Disclosed is a resin-mold integrated semiconductor device in which an alloy layer of solder and lead frame constituent metal is formed on the lower surface of the outer lead after cutting simultaneously with cutting.

Further, the present invention includes a resin including a first step of subjecting a lead frame of a resin-molded integrated semiconductor device to a solder plating treatment and a second step of cutting a dam bar of the lead frame subjected to the solder plating treatment with a laser beam. A method for manufacturing a mold integrated semiconductor device is disclosed.

Further, the present invention discloses a method of manufacturing a resin mold integrated semiconductor device including a third step of cutting a solder-plated outer peripheral lead frame with a laser beam.

Further, the present invention is an apparatus for manufacturing a resin mold integrated semiconductor device, which comprises a plating processing device for performing a solder plating process and a dam bar processing device for cutting the dam bar of the lead frame subjected to the solder plating process with a laser beam. Is disclosed.

[0017]

[Function] Tin / zinc alloy solder has a low melting point, and at the same time, when it melts on the surface of the lead frame constituent metal, it forms a thin alloy composition with the surface to improve the wetting, and makes a strong contact with a large area. It has the property of exhibiting various adhesive effects. Therefore, when the lead frame subjected to the solder plating treatment is blown by the laser beam, the solder at the cut portion is remelted and reacts with the lead frame metal, and the produced alloy is re-dissolved on the lower surface of the cut portion. Since this solid solution has very good wettability with the lead frame metal as described above, it exhibits a strong adhesive force and is not separated even by vibration or the like.

[0018]

EXAMPLES The present invention will be described in more detail based on the following examples. FIG. 1 is a block diagram showing an example of a manufacturing process of a resin mold integrated semiconductor device according to an embodiment. Process F1 is the preparation of a metal material for a lead frame.
Copper alloy and iron / nickel alloy plates are commonly used. Process F2 is cleaning and pressing by chemical etching of the material surface. By this process, for example, the pattern of the lead frame 2 as shown in FIG. 3 is cut out.

Process F3 is the mounting of a Si semiconductor chip which has been integrated into an IC through various steps. The lead frame is mounted at a predetermined position by so-called die bonding. Then, wire bonding is performed in process F4, and the chip /
Join between leads. Thereafter, resin molding is performed to protect the semiconductor chip and wiring mounted in the process F5. At this time, the fluid resin overflowing from the cavity of the resin mold is collected and solidified in the dam 11 provided between the leads. The dam bar 3 prevents the resin from spreading to the outer lead 6 side. A top view of the resin-molded semiconductor device 7 thus obtained is shown in FIG. The semiconductor device shown in the figure is a so-called QFP (quad).
It is mounted on a rate flat package type frame. This type of frame is for mounting high-density integrated circuits and is a fine lead frame with a lead interval of 0.5 mm or less. In addition, 2 of FIG. 3 shows the lead frame pattern cut out in the process F2. Positioning hole 1 for cutting and taking out the lead frame in a later process
Are provided on both sides of the lead frame.

Next, in process F6, the lead frame metal material is subjected to solder plating. This treatment is usually performed by an electroplating process in which the tin / zinc alloy is layered onto the leadframe metal. It is obvious that the resin-molded semiconductor device cannot be plated.

Then, in process F7, the dam bar 3 is cut by the laser beam 9, and the leads are not in contact with each other except in the outer peripheral portion (the area outside the dotted line in FIG. 3). FIG. 4 is a perspective view showing a state after this process is performed. On the lower surface of the lead frame where the dam bar 3 is cut, the solder / lead frame intermetallic alloy 5 formed between the solder component and the lead frame metal, which has once melted and then wraps around the lower surface under the influence of gravity, is fixed in layers. The situation is shown. The BB cross-sectional view is shown in an enlarged manner. Since the solder / lead frame intermetallic alloy 5 shown in FIG. It is characterized in that it does not sag and spreads laterally in layers to form a solid solution with the lead frame 2.

On the other hand, conventionally, as shown in FIG. 2B, the solder plating process is performed after the cutting process of the dam bar 3 by the laser beam 9. This is the opposite of the embodiment of the present invention shown in FIG. As a result, according to the conventional example, as shown in FIG. 5B, the local melting of the lead frame 2 by the laser beam 9 often caused the formation of the dross 4 on the lower surface of the lead frame 2. .
This is because the droplets made of the same material are strongly affected by gravity and the area of the fixed portion with the lead frame 2 is reduced. The dross 4 has a small fixed part area,
It is fragile even if it is oxidized in the process of solidification of the fixed portion, and it is broken by mechanical vibration or pressure to become metal dust, which causes troubles.

In FIG. 1, after cutting the dam bar 3 in process F7, the outer peripheral lead frame is cut in process F8 to separate the semiconductor device from the lead frame plate. For example, cutting may be performed from a portion A indicated by a dotted line in FIG. This cutting can be performed by pressing. When the dam bar 3 is cut and the outer peripheral lead frame is cut, the positioning holes 1 shown in FIG. 3 are used to perform detailed positioning of the plate.

The cutting of the outer peripheral lead frame in the process F8 can be performed by using the laser beam 9 as in the cutting of the dam bar 3 in the process F7. This situation is shown in FIG. As shown, due to the heat generated when the lead frame 2 is cut by the laser beam 9 that is narrowed down by the condenser lens 8,
A synergistic liquid between the solder and the metal of the lead frame is generated, which wraps around the lower surface of the lead frame and accumulates on the lower surface due to surface tension. However, since this synthetic financial liquid is a metal different from the lead frame metal containing the lead frame metal component, it is very wettable with the lead frame metal and spreads laterally to be fixed in a large area. The cross section C-C of FIG.
As shown in (A), the solder / lead frame intermetallic alloy 5 is formed on the lower surface of the lead frame 2 without any fear of separation and drop in the later process.

When the cutting with the laser beam 9 is used, even if the outer peripheral lead frame is cut after the dam bar 3 is cut as described above after the solder plating in the process F6, the laser beam is not cut after the outer lead frame is cut. Laser beam cutting of the dam bar 3 may be performed.

However, if the laser beam cutting of the outer peripheral lead frame is performed before the solder plating process F6, an unstable dross 4 is formed at the cut portion of the outer peripheral lead frame, as in FIG. 5B. It causes trouble in the later process. Therefore, cutting the dam bar 3 and / or the outer peripheral lead frame by the laser beam 9 before the solder plating is outside the scope of the present invention.

Returning again to FIG. After the outer peripheral lead frame is cut in the process F8, the outer lead 6 is bent and shaped in the process F9 so that it can be mounted on the printed circuit board as it is. Further, in process F10, characters, symbols such as a model, a product number, a manufacturing factory, and a manufacturer's name are marked on the side surface, the back surface, or the front surface of the product. In recent years, laser marking has been widely used. Then, the product is completed by inspecting and packing in the process F11.

In another embodiment of the present invention, as described above, F8 can be cut by the laser beam 9 in the process of FIG. 1, or F7 and F8 can be interchanged. If the outer peripheral lead frame of the process F8 is cut by press working, it is possible to insert F8 before the process F6 of the solder plating process. By doing so, it is not necessary to perform solder plating on unnecessary portions of the lead frame 2, and the solder raw material can be saved.

The main manufacturing process of the present invention, F6 to F8 in FIG. 1, can be controlled by the system shown in FIG. The lead frame 2 on which the resin-molded semiconductor device is mounted is transported from the left side to the right side in FIG. In the transportation process, the transportation control device 20 detects the working speed and the transportation state of each semi-finished product and controls the transportation speed and the transportation mode. Further, the plating processing device 21 for performing the solder plating process of the process F6, the process F7
Sequence control of the dam bar processing device 22 that cuts the laser beam of the dam bar 3 and the outer circumference lead frame processing device 23 that performs the outer circumference lead frame cutting of the process F8, for example, a laser beam or a press cutting machine. A management device 24 that can also control the operation is provided.

The embodiment shown in FIG. 7 enables implementation of the main part of the invention whose process is shown in FIG.

[0031]

As described above, according to the present invention, it is possible to suppress the formation of dross which has been conventionally generated at the time of cutting the dam bar and / or the outer peripheral lead frame with the laser beam. Since droplets that become dross can be converted into a stable alloy solid solution during the commercialization process, it does not lead to cost increase and can prevent troubles due to dross delamination in the subsequent process and contribute to the improvement of product yield. it is conceivable that.

[Brief description of drawings]

FIG. 1 is a block diagram showing a manufacturing process according to an embodiment.

FIG. 2 is a comparison diagram of an example of a solder plating / dam bar cutting process and a conventional example.

FIG. 3 shows a top view (before cutting the lead frame) of a QFP type resin mold integrated semiconductor device.

FIG. 4 is a perspective view showing an example of dam bar cutting according to an example.

FIG. 5 is a diagram comparing an example of a laser beam cut or a lead frame cross section with a conventional example.

FIG. 6 is a perspective view showing a laser beam cutting state of an outer peripheral lead frame according to an example.

FIG. 7 is a block diagram showing a process control system according to an embodiment (corresponding to processes F6 to F8 in FIG. 1).

[Explanation of symbols]

 1 Positioning Hole 2 Lead Frame 3 Dam Bar 4 Dross 5 Solder / Lead Frame Metal Alloy 6 Outer Lead 7 Resin Molded Semiconductor Device 8 Condenser Lens 9 Laser Beam 11 Dam A Outer Lead Frame (Laser Cutting Section)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiaki Shimomura 650 Kazutachi-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura factory (72) Inventor Shinya Okumura 650 Kintate-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Ceremony Company Tsuchiura Plant (72) Inventor Yoshiya Nagano 650 Kintatecho, Tsuchiura City, Ibaraki Prefecture Hitachi Construction Machinery Co., Ltd.Formula Company Tsuchiura Plant (72) Inventor Nobuyuki Kimura 650 Kintatecho, Tsuchiura City, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura factory

Claims (10)

[Claims] 1. A resin mold integrated semiconductor device obtained by laser cutting a dam bar after solder plating. 2. A resin mold integrated semiconductor device in which a dam bar is laser-cut and a peripheral lead frame is laser-cut after a solder plating process. 3. The resin mold integration according to claim 1, wherein in the laser cutting process, an alloy layer of solder and lead frame constituent metal is formed on the lower surface of the outer lead after cutting simultaneously with cutting. Semiconductor device. 4. The semiconductor device integrated with a resin mold is a semiconductor device formed on a QFP type fine lead frame having a plurality of outer leads protruding from four sides with a pitch width of 0.5 mm or less. The resin mold integrated semiconductor device described. 5. A resin mold integration including a first step of subjecting a lead frame of a resin-molded integrated semiconductor device to a solder plating treatment and a second step of cutting a dam bar of the lead frame subjected to the solder plating treatment with a laser beam. Manufacturing method of semiconductor device. 6. The method of manufacturing a resin-mold integrated semiconductor device according to claim 5, further comprising a third step of cutting the solder-plated outer peripheral lead frame with a laser beam. 7. The laser cutting process is a process for forming an alloy layer of solder and lead frame constituent metal on the lower surface of the outer lead after cutting simultaneously with the cutting.
Alternatively, the method for manufacturing a resin mold integrated semiconductor device according to 6). 8. The resin mold integrated semiconductor device comprises:
6. The method of manufacturing a resin-mold integrated semiconductor device according to claim 5, wherein the semiconductor device is formed on a QFP type fine lead frame having a plurality of outer leads protruding from four sides with a pitch width of 0.5 mm or less. 9. The resin mold integrated semiconductor device comprises:
The method for manufacturing a resin mold integrated semiconductor device according to claim 5, which is formed on a QFP type fine lead frame. 10. An apparatus for manufacturing a resin mold integrated semiconductor device, comprising: a plating processing device for performing a solder plating process; and a dam bar processing device for cutting the dam bar of the lead frame subjected to the solder plating process with a laser beam.