JP2795237B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device having a step of sealing a semiconductor chip fixed to a lead frame with a resin.

[0002]

2. Description of the Related Art A dam bar provided on a resin-encapsulated semiconductor device lead frame serves to prevent resin from flowing between outer leads during resin encapsulation. However, since each lead is short-circuited by this dam bar,
It is necessary to cut this dam bar with a dam bar cutting die after resin sealing, and to electrically isolate each lead.

However, due to the recent trend toward miniaturization and high performance of semiconductor devices, the pitch of external terminals has been reduced (0.3 / 0.4).
mm), the punch of the die for cutting the dam bar is also miniaturized, and in consideration of the durability of the punch and the like, it has become difficult to cut the dam bar by the conventional die.

[0004] Against this background, resin dam bar technology, which eliminates the need for punching itself and has significant significance in terms of reducing the number of assembling steps, has attracted attention and is being put into practical use.

The resin dam bar is a resin dam bar in which an insulating resin material is buried near the boundary between the inner lead and the outer lead. It can be considered that a conventional metal dam bar is made of an insulating resin material. In the frame, since the insulation between the leads is maintained, there is no need to cut the dam bar with a mold after resin sealing. The technology relating to such a resin dam bar is disclosed in, for example,
No. 187842, JP-A-3-218032 and the like.

The prior art will be described with reference to FIGS. First, as shown in FIG.
, The island 11 on which the semiconductor pellet is mounted is suspended by the four suspension pins 14, the inner lead 12 is formed continuously from the outer lead 13, and the tip of the inner lead 12 faces the island 11. The holes are arranged, and a positioning hole, a feed hole, and a kind identification hole 15 are formed. Further, in the same figure, a mold edge 20 showing a side end portion of the mold resin is indicated by a dashed line.

As shown in FIG. 7, the basic structure of a conventional lead frame of resin dam bar specification using this lead frame 10 is a boundary between an inner lead 12 and an outer lead 13 in the lead frame 10, that is, a mold edge 20. Is coated with an insulating resin material to function as a resin dam bar 31.

As the insulating resin material, an ultraviolet curable resin,
Soluble heat-resistant resins (polycarbonate, polyphenylene oxide, polysulfone), high heat-resistant resins (polyimide, silicone resin, epoxy resin) and the like are generally used.

Various methods such as a screen printing method, a dispensing method, and a photographic printing method have been proposed as a method of applying the insulating resin material. It is advantageous.

In order to form a resin dam bar by the screen printing method, first, as shown in FIG. 8A, a through hole 53 for a resin dam bar is formed in a stainless steel mesh 51 so as to obtain a desired resin dam bar shape. Emulsion 5
2 is applied uniformly to produce a screen printing plate 50.

[0011] Then, the lead frame 10 and the screen printing plate 50 are overlapped, and the insulating resin material 3 previously coated on the plate is rubbed on the mesh 51 with the squeegee 7. 1
8 with the insulating resin material 3 buried in a predetermined position of FIG.
As shown in (B), a resin dam bar 31 is formed.

FIG. 9 is an example of a plan view of the screen printing plate after the emulsion coating. Emulsion 52 is applied to one surface of the mesh except for four portions (through holes for resin dam bar) 53 corresponding to the resin dam bar.

[0013]

Although the use of a resin dam bar specification lead frame can greatly reduce the number of steps or reduce the pitch of external terminals, there are various problems in the actual assembly process. Is known to occur. According to the investigation by the inventor of the present invention, the resin dam bar is peeled or missing, or the inner lead is deformed due to vibration or heat during the bonding step, the resin sealing step, or the product transfer between the steps. It is effective to fix the inner lead with a polyimide tape for deformation of the inner lead, and it can be almost completely suppressed. Regarding the position where the tape is applied, in FIG. 10, the tape is generally disposed on the inner lead 12 so as to be inside the mold edge 20 and to surround the outside of the island 11. By sticking to the forefront part of the lead, the deformation of the inner lead can be further suppressed, and the bonding property can be improved. The technique of preventing the deformation of the inner lead by attaching the insulating tape in this manner is disclosed in, for example,
-27236.

However, fixing with a tape as described above requires an extra tape material cost, which hinders the cost reduction of the semiconductor device.

Further, since the stability of the frame is increased by fixing the inner leads, the peeling and dropping of the resin dam bar can be suppressed. Therefore, when the fixing of the inner leads is applied to a resin dam bar specification lead frame, The step of fixing the leads and the step of forming the resin dam bar are required separately, which increases the number of manufacturing steps.

Therefore, an object of the present invention is to provide a method without requiring a special material cost and without increasing the number of steps.
An object of the present invention is to provide a method of manufacturing a semiconductor device capable of realizing an inner lead fixing and a resin dam bar.

[0017]

A feature of the present invention is to provide a method of manufacturing a resin-encapsulated semiconductor device using a lead frame, wherein the lead frame has a portion near a boundary between an inner lead and an outer lead and an inner portion near an island. Insulating resin material is applied to each of the lead portions in a strip-like manner in the same process , and is applied to the inner lead portion near the island due to the thickness of the insulating resin material applied to the portion near the boundary between the inner lead and the outer lead. Oh the thickness of the insulating resin material which is the method of manufacturing a thick Kusuru semiconductor device
You. In this case, it is preferable to apply the insulating resin material having the different film thickness by changing the film thickness of the emulsion in each portion of the screen printing plate . In addition, as the insulating resin material, an epoxy-based resin, a urethane-based resin, or an ultraviolet curable resin obtained by mixing them can be used .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a view showing a technique related to the present invention. FIG. 1 (A) is a plan view of a resin dam bar specification lead frame, and FIG. 1 (B) is a semiconductor device obtained by the manufacturing method. It is sectional drawing of the state isolate | separated from the lead frame.

In FIG. 1A, a lead frame 10
The island 11 on which a semiconductor pellet is mounted is suspended by four suspension pins 14, and a large number of leads, on which the inner leads 12 are continuously formed from the outer leads 13, are arranged around the island 11. That is, the tips of the inner leads 12 are arranged with the tips facing each side of the island 11. Further, a positioning hole, a feed hole, and a kind identification hole 15 are formed. Also,
A mold edge 20 showing a side end of the mold resin in FIG.
Is indicated by a dashed line.

Four band-shaped resin dam bars 31 are formed on the boundary between the inner lead 12 and the outer lead 13, that is, on the outside of the mold edge 20 so as to surround the inside, and the inner lead near the island 11 is formed. A belt-shaped inner lead fixing member 32 is formed in a ring shape surrounding the island at a portion 12.

The resin dam bar 31 and the inner lead fixing material 32 are made of an insulating resin material made of an epoxy-based, urethane-based, or UV-curable resin obtained by mixing them. By filling, the leads are mechanically connected. However, since the insulating resin material is used, each lead is electrically insulated and separated. And resin dam bar 31
The inner lead fixing member 32 and the inner lead fixing member 32 are simultaneously formed by a screen printing method, that is, formed by being applied in the same process.

The semiconductor chip 2 is fixedly mounted on the island 11 of the resin dam bar specification lead frame shown in FIG. 1A, and the electrode 2E of the semiconductor chip 2 and the tip of the inner lead 12 are connected by wire bonding with the bonding wire 4. , Mold edge 9 by molding resin 9
The semiconductor device as shown in FIG. 1 (B) is obtained by enclosing the inside and cutting off the tip of the outer lead from the lead frame main body.

FIG. 2 is a view showing a process for manufacturing the resin dam bar specification lead frame shown in FIG. 1 by a screen printing method, and FIG. 2 (A) is a cross section showing a state of screen printing on a screen printing plate. FIG. 2B is a side view showing a lead frame on a screen printing table. FIG. 3 is a plan view of the screen printing plate.

Referring to FIGS. 2 (A) and 3, an emulsion 42 is selectively applied to the back surface of a stainless steel mesh 41 of the screen printing plate 40 to obtain a desired resin dam bar shape and a fixed inner lead shape. Thus, the through hole 43 for the resin tie bar and the through hole 44 for the inner lead are formed.

The screen printing plate 40 contacts the emulsion side with the lead frame 10 placed on the protective sheet 5 on the screen printing table 6 as shown in FIG.
The insulating resin material 3 is rubbed with a squeegee 7 to form an emulsion 4
2 through the resin tie bar through-hole 43 and the inner lead through-hole 44, and buried in a predetermined position between the leads of the lead frame 10 installed on the screen printing table 6, thereby forming the resin dam bar 31 and the inner lead. Fixing material 3
2 are formed simultaneously. Since the insulating resin material 3 has a sufficient thixotropic property, the resin dam bar 31 and the inner lead fixing material 32 have substantially the same planar shape as the through holes 43 and 44.
Are respectively formed. The protective sheet 5 has a function of preventing the insulating resin material from protruding to the back surface of the lead frame.

As described above, by improving the pattern of the screen printing plate, the fixing of the inner lead and the formation of the resin dam bar can be performed at the same time without increasing the number of steps.

Normally, when the resin dam bar 31 is formed by burying an insulating resin material near the outside of the mold edge as shown in FIG. 1, the resin dam bar 31 is removed after the step of FIG. Make a product.

However, the application position of the resin dam bar is not limited to the vicinity of the outside of the mold edge 20, but may be provided near the inside of the mold edge 20 or on the mold edge 20 as shown in FIG. That is, when the resin dam bar 31 is not removed during the assembling process and is left in the product in the state of FIG. 4B, the application form as shown in FIG. 4A is effective.

According to the investigation by the present inventors, as an insulating resin material to be applied, an epoxy-based resin, a urethane-based resin, or a UV-curable resin obtained by mixing them is used, so that any heat or heat during the assembling process can be obtained. Sufficient resistance to impact can be exhibited, and sufficient reliability can be realized even for fixing the inner lead. This is due to the observation of delamination inside the semiconductor device by the temperature cycle test after the water absorption heat treatment.
On the upper surface of the device, it was almost the same, but on the lower surface of the device, in the case of the polyimide tape, peeling had already occurred in 100 cycles, whereas in the insulating resin material, no peeling was observed up to 200 cycles. Has been confirmed from.

As an embodiment of the present invention, a resin dam bar specification lead frame in which the applied thickness of the insulating resin material is different between the resin dam bar portion and the inner lead fixing portion will be described.

FIG. 5 shows an embodiment using a screen printing method.
It is a diagram showing a state, FIG. 5 (A) cross-sectional view showing a state of a screen printing on the screen printing plate, FIG. 5 (B) is a side view showing a lead frame on the screen printing stage.

The emulsion 42 is applied to the back surface of the stainless steel mesh 41 so that the peripheral region 42A forming the resin tie bar through hole 43 is thin and the central region 42B forming the inner lead through hole 44 is thick. When the screen printing plate 40 is pressed onto the lead frame 10, the periphery of the screen printing plate 40 bends downward, and the peripheral region of the emulsion comes into contact with the lead frame 10 on the screen printing table 6.

When the insulating resin material 3 is screen-printed in this state, the resin dam bar 31 and the inner lead fixing material 32 higher than this are formed at the same time.

That is, the amount of protrusion of the lead frame 10 from one surface (the upper surface in the drawing) of the inner lead fixing member 32 is larger than that of the resin dam bar 31.

In general, the resin material for fixing the inner leads is often peeled off or missing from the resin dam bar due to vibration, heat, impact or the like during the assembly process. Therefore, by increasing the thickness of the inner lead fixing resin material as compared with the resin dam bar (by increasing the thickness in the thickness direction of the lead frame), the resistance to vibration, heat, and shock can be enhanced.

That is, in the resin dam bar specification lead frame shown in FIG. 1, the yield in the assembling process can be improved by changing the coating thickness of the inner lead fixing member 32 and the resin dam bar 31, and the above-described method is often used. The inner lead fixing member 32 and the resin dam bar 31 having different thicknesses can be simultaneously formed.

Further, in order to enhance the adhesion between the lead frame 10 and the screen printing plate 40, as shown in FIG. 6, the emulsion lead frame side (the lower side in the figure) is flattened, and the emulsion is placed on the opposite side (the upper side in the figure). Step, stainless steel mesh 4
By depressing 1, a screen printing plate whose periphery is bent downward in the figure can be formed.

[0039]

As described above, according to the present invention, in the resin dam bar specification lead frame, the inner leads are fixed by using the same insulating resin material as the resin dam bar, and the resin dam bar is formed by the screen printing method. Since this is performed simultaneously, the inner leads can be fixed without increasing the number of manufacturing steps, and deformation of the inner leads can be suppressed. In addition, since it is not necessary to fix with tape, there is an effect that the material cost can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a technique related to the present invention;
(A) is a plan view of a resin dam bar specification lead frame,
(B) is a cross-sectional view of the semiconductor device obtained by the manufacturing method in a state separated from a lead frame.

FIGS. 2A and 2B are views showing steps of manufacturing the resin dam bar specification lead frame shown in FIG. 1 by a screen printing method, wherein FIG. 2A is a cross-sectional view showing a state of screen printing on a screen printing plate; () Is a side view showing the lead frame on the screen printing table.

FIG. 3 is a plan view of the screen printing plate of FIG. 2;

[Figure 4] is a diagram showing a partially modified technique of FIG. 1,
(A) is a plan view of a resin dam bar specification lead frame,
(B) is a cross-sectional view of the semiconductor device obtained by the manufacturing method in a state separated from a lead frame.

5A and 5B are diagrams showing a screen printing method according to the embodiment of the present invention, in which FIG. 5A is a sectional view showing a state of screen printing on a screen printing plate, and FIG. FIG.

6A and 6B are diagrams showing a screen printing method in an embodiment in which the screen printing plate of FIG. 5 is changed, wherein FIG. 6A is a cross-sectional view showing a state of screen printing on the screen printing plate, and FIG. It is a side view which shows the lead frame on a stand.

FIG. 7 is a plan view showing a resin dam bar specification lead frame according to the related art.

8A and 8B are diagrams showing a process in the case of manufacturing the conventional resin dam bar specification lead frame shown in FIG. 7 by a screen printing method, and FIG. 8A is a cross-sectional view showing a state of screen printing on a screen printing plate. (B) is a side view showing the lead frame on the screen printing table.

FIG. 9 is a plan view of the screen printing plate of FIG. 8;

FIG. 10 is a plan view showing a lead frame.

[Explanation of symbols]

 Reference Signs List 2 semiconductor chip 2E electrode 4 bonding wire 5 protective sheet 6 screen printing stand 9 mold resin 10 lead frame 11 island 12 inner lead 13 outer lead 14 hanging pin 15 various holes 20 mold edge 31 resin dam bar 32 inner lead fixing material 40, 50 Screen printing plate 41,51 Stainless steel mesh 42,52 Emulsion 42A Peripheral area of emulsion 42B Central area of emulsion 43,53 Through hole for resin tie bar 44 Through hole for inner lead

Claims (3)

(57) [Claims] 1. A method of manufacturing a resin-encapsulated semiconductor device using a lead frame, wherein an insulating resin material is formed in a strip shape on a portion near a boundary between an inner lead and an outer lead and a portion on an inner lead near an island. In the same process , and
Insulation applied near the boundary between the lead and outer lead
Inner lead near the island from the thickness of the resin material
A method of manufacturing a semiconductor device, comprising increasing the thickness of an insulating resin material applied to a portion of the semiconductor device. 2. The method of manufacturing a semiconductor device according to claim 1, wherein said insulating resin material having a different thickness is applied by varying the thickness of the emulsion in each portion of the screen printing plate. 3. The method of manufacturing a semiconductor device according to claim 1, wherein an epoxy-based resin, a urethane-based resin, or a UV-curable resin obtained by mixing them is used as said insulating resin material.