JPH07135230A - Electronic device resin sealing method and lead frame provided therefor - Google Patents

Abstract

PURPOSE:To lessen resin wasted in a throwaway part such as a cull or a runner in quantity so as to reduce the amount of resin used to an irreducible minimum and to enhance resin material in use yield in a resin sealed-type semiconductor package of an electronic device. CONSTITUTION:A lead frame 1 is equipped with a resin tablet hole 5 at its center where a resin tablet of molding material is located, the resin tablet hole 5 is regarded as a cull (pot), and four gates 12 are provided around the resin tablet hole 5 in a radial manner, and also the lead frame 1 is provided with semiconductor device forming region ICs where semiconductor devices are mounted and which are provided corresponding to the gates 12. Resin is directly poured into a cavity from a pot through the gates 12 connected to the cavity without using a runner. By this setup, a pot is disposed at the center of a lead frame, so that a distance between the pot and a cavity is short, and resin wasted in a throwaway part such as a cull or a runner used in a conventional molding structure can be lessened in amount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing technology (packaging technology) for electronic devices, and is particularly effective for semiconductor resin molding technology.

[0002]

2. Description of the Related Art In the field of semiconductor technology, resin molding technology called transfer molding method, which is inexpensive and has high mass productivity, is the mainstream as a sealing technology. In recent years, there has been a demand for high-density packaging and a thinner package body.
In particular, one problem with the thinning of the package body is
The decrease in reliability due to the hygroscopicity of the molding resin (resin) can be mentioned. In order to improve the moisture resistance, it is considered to use a resin with low hygroscopicity.This low hygroscopic resin is suitable for making the package thin, but the cost is higher than the epoxy resin that is generally used. There's a problem.
For this reason, the amount of resin to be discarded is reduced as much as possible, and effective use of the resin has become a problem.

As a transfer molding method for effectively utilizing a resin material, a multi-pot type method is proposed in which a plurality of pots are provided and each runner is uniformly formed so that the distance from the pot to the cavity does not become long. Has been done.

A transfer molding method using a die called a multi-pot type or a multi-plunger type is disclosed in, for example, Japanese Patent Laid-Open Nos. 1-196319 and 3-1993.
It is known from JP-A-278923.

[0005]

Even in the conventional molding method described above, the amount of resin to be discarded is still large in comparison with the amount of resin originally used in the semiconductor device. The yield used was low.

As described above, a highly reliable low moisture absorption resin is becoming the mainstream as the package becomes thinner. However, this low hygroscopic resin (for example, biphenyl resin) is higher in cost than the epoxy resin which is generally used in the past. Therefore, more effective use of resin was needed.

That is, it is an object of the present invention to minimize the amount of resin used in the resin molding process to the necessary minimum.

The above and other objects and novel characteristics of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0009]

The outline of the representative one of the inventions disclosed in the present application will be briefly described as follows.

That is, according to the present invention, a lead frame having a hole in which a resin tablet of a molding material is located at the center and a plurality of semiconductor device forming regions radially located around the hole is prepared. The cavity of the mold is positioned corresponding to the mold pot and the resin-sealed partitioning region of the semiconductor device formation region, and the resin is poured into the cavity from the pot through a gate directly connected to the pot.

[0011]

According to the above-mentioned means, the distance from the pot to the cavity is shorter than that of the conventional multi-pot molding method in which the resin is poured from the pot through the runner into the gate and then into the cavity. The amount of resin spent in the discarded portion can be reduced, and the usage fee of the resin material can be reduced.

Further, in the conventional mold, the pot and the runner portion are formed at positions separated from the lead frame.
According to the present invention, since the pot portion is located within the lead frame, space efficiency of the mold is improved and productivity can be improved.

Further, according to the present invention, since the resin is injected from the pot portion into the semiconductor device forming regions radially arranged, the resin injection amount into each semiconductor device forming region becomes uniform, and the thin package can be manufactured. Yield can be improved.

[0014]

【Example】

(Embodiment 1) The present invention will be described based on a specific embodiment with reference to the drawings.

FIG. 1 is a partial top view of a lead frame applied to the assembly of a resin mold type semiconductor device according to the present invention, and FIG. 2 is an enlarged top view showing one semiconductor device forming region in the one-dot chain line frame in FIG. 3 is a cross-sectional view taken along the line AA of FIG. 1 in the molded product, FIG.
6 is a front cross-sectional view of the molding apparatus used in this embodiment, FIG. 7 is a top view showing the layout of the mold used in this embodiment,
8 is a side view of the product after completion of the molding, FIG. 9 is a side view showing a form in which the products after the completion of molding are stacked, FIG. 10 is an enlarged top view of a portion B in FIG. 1, and FIG.
12 is a sectional view corresponding to the section C-C shown in FIG. 12, and FIG. 12 is a sectional view corresponding to the section D-D shown in FIG. 10 after molding.

In FIG. 1, a lead frame 1 is provided with a resin tablet hole 5 in the center thereof, in which a cylindrical resin tablet is to be positioned, which is slightly larger than the diameter of the resin tablet.

Here, as described above, by providing a hole slightly larger than the diameter of the resin tablet in the portion corresponding to the pot of the lead frame, the resin tablet can be easily arranged at a predetermined position during the molding process.

The resin tablet hole 5 is provided with relatively projecting holes 5a and 5b. This protruding hole 5a,
5b will be described later. Then, four semiconductor device forming regions IC, each unit of which is defined by a one-dot chain line frame, are radially provided around the resin tablet hole 5, and the lead frame pattern in each unit of the semiconductor device forming region will be described later. It is configured to

Further, in FIG. 1, the stress absorbing holes 19 are provided to prevent deformation of the leads due to thermal expansion of the lead frame 1. The slit 15 and the slit 6 are
These are for preventing the resin from leaking from the cull portion 9 and the communication passage 11 during molding. Here, in FIG. 1, the range in which the resin is filled after molding is indicated by a broken mold line 13. The lead frame 1 is a thin plate (thickness: 0.15 m, for example, made of an iron-nickel (Fe-Ni) alloy or a copper (Cu) alloy.
m) is used and is formed by means of punching press work or etching work.

FIG. 2 shows the IC (unit semiconductor device forming region) in FIG. 1. Here, the IC has a tab 30 for mounting (fixing) a semiconductor pellet 31, and this tab 30 is a tab. The inner leads 2, the outer leads 3, are held on the lead frame by the suspension leads 32.
It is composed of a dam 4. That is, in FIG. 2, the tip of the inner lead 2 and the bonding pad 33 are electrically connected by the bonding wire 34,
The outer lead 3 enables input / output of an electric signal from the outside or a semiconductor element. Also, the outer lead 3
A dam 4 is provided between the leads for preventing the resin from leaking during molding, and the dam 4 is punched out after molding. Here, the flow of the resin at the time of molding will be described with reference to FIG. 31 and the inner lead 2 will be molded.

Next, the relationship between the mold and the lead frame in this embodiment will be described.

Since a plurality of plungers (not shown) connected to each other simultaneously pressurize and mold a plurality of resin tablets, if the amount of the resin tablets put in the pot varies, a difference in pressure is applied to each pot. However, there arises a problem that uniform molding cannot be performed. In order to prevent this, in this embodiment, as shown in FIG. 1, a communication passage 1 is provided between adjacent pots.
A portion corresponding to 1 is provided in the mold, and when the amount of the resin tablet in each pot is different, the resin passes through the communication passage 11 to make the amount of resin in each pot uniform, that is, it is added to each pot. The pressure is made uniform.

The flow cavity 10 shown in FIGS. 1 to 3 is an auxiliary cavity that allows the air existing in the cavity to escape during molding, and is provided in the mold to reduce voids. Are provided in three places corresponding to the corners.

The lead frame 1 is a flow cavity 10
A hole 7 is provided at a position located inside. This hole 7
Acts as a hole for the resin to bite so that the resin remaining in the flow cavity 10 after the mold is released does not easily fall off. As shown in FIG. 3, the resin injected into the flow cavity 10 at the time of molding flows into the front and back of the lead frame 1 through the holes 7 and is supported from the front and back of the lead frame 1. Further, as shown in FIG. 1, a hole 8 is also provided at a position corresponding to the communication passage 11, but this is also intended to prevent falling off, like the hole 7. That is, the resin injected into the communication passage 11 is retained by fitting a part of the resin into the hole 8. Similar to the hole 8, the resin is also inserted into the resin tablet hole 5 in the cull portion 9 in FIG. 3, so that the resin in the cull portion can be prevented from falling off.

Next, the molding method of this embodiment will be described step by step with reference to FIGS. 4 to 6, the flow cavity portion in FIG. 3 is omitted.

First, as shown in FIG. 4, the semiconductor pellet 3
1 is fixed, and the assembly lead frame 21 in which the tips of the inner leads 2 and the bonding pads 33 are connected by the bonding wires 34 is attached to the resin tablet 25.
The transfer position is set on the lower mold 23 in which the is charged. Then, the upper die 22 is set on the lower die 23.
In the next step, the molds are clamped as shown in FIG. 5, and the resin tablet 25 is pressed by the plunger 24 as shown in FIG. Fill the resin with. After this,
The molded lead frame (product) is taken out after the resin is cured. FIG. 7 is a schematic top view showing the layout of the lower mold used in this embodiment. This lower mold has a structure in which a lead frame mounting portion 36 in which the lead frame is positioned and a pot 26 into which the resin tablet 25 is placed are formed in the lead frame mounting portion.

In the molded lead frame, as shown in FIG. 8, the relationship between the resin thickness h1 of the cull portion 9 and the package lower thickness h2 and the package upper thickness h3 is h2 <h.
By setting 1 <h2 + h3, as shown in FIG. 9, the package body 16 can be directly stacked on the spacer 26 having a hole at the lowest portion where the cull 9 abuts, and the resin of the cull portion 9 can be stacked. Serves as a stopper to prevent lateral slippage, and stacking and transporting can be performed without using a dedicated transporting jig, and the efficiency of transporting and storing space is improved.

After the molding is completed, the unnecessary cull 9 must be removed. A partial structure of the lead frame devised for this removal will be described with reference to FIGS. 10 to 12.

First, FIG. 10 is an enlarged view of portion B in FIG. FIG. 11 shows a cross sectional view corresponding to the CC cross section of FIG. 10 after the resin molding. Then, FIG. 12 shows a cross-sectional view corresponding to the DD cross section of FIG. 10 after the resin molding.

After molding, the resin from the lead frame 1 to the cull portion 9 is cut and removed along the line C--C shown in FIG. Since the protruding hole 5a protruding to the right side of the CC cutting line is extended so that a part of the lead frame and the resin of the communication passage 11 do not overlap with each other, the CC cutting cross section is shown in FIG. As shown in FIG. 11, it is divided into a lead frame 1 (metal) surface and a resin 17 surface. That is, since the metal is sheared and the resin has different cutting properties from cracking, a metal-only part on the same cutting surface,
The presence of the metal and the resin overlapping portion makes it particularly difficult to cut the overlapping portion. Therefore, as shown in FIG. 11, the overlapping portion of the lead frame 1 and the resin 17 is eliminated, and the lead frame 1 is divided into specifications for cutting the lead frame, and the resin 17 is divided into specifications for cutting the resin. It is possible to cut by lowering the cutting blade S as shown by the arrow. Furthermore, in order to make it easier to cut, the groove 18 having a chevron shape as shown in FIG.
Prepare a mold that can be provided with a groove 18 at the time of molding.
By providing the above, the stress concentrates on the groove 18 at the time of cutting by lowering the cutting blade S as shown by an arrow, and thus the cull portion 9 can be easily cut (cracked).

(Embodiment 2) Although Embodiment 1 is an embodiment in which the assembly-completed lead frame 21 is molded in one step, another embodiment in which the assembly-completed lead frames 21 are arranged in upper and lower two tiers and molded, This will be described with reference to FIGS. 13 to 16.

13 to 16 are front sectional views showing a two-step molding step using the two-step molding apparatus.

First, as shown in FIG. 13, the tablet 25 is set in the pot 26 of the lower mold 23, and the assembled lead frame 2 corresponding to the cavity of the first stage is completed.
1 is set. Next, the middle mold 27 constituting the upper and lower cavities is set, and the assembly completed lead frame 21 is set in correspondence with the second-stage cavity. Then, the upper mold 22 is set on the middle mold 27. Next, as shown in FIG. 14, each mold is clamped, the tablet 25 is pressed by the plunger 24, and the resin is filled into each cavity 20 through the gate as shown in FIG. After this, wait for the resin to cure and then press the upper mold 2
By removing 2 and making Cull 9 break the gate,
The package 29 can be taken out as shown in FIG. The planar structure of the mold in each stage has the structure shown in FIG. 7, and therefore the applicable lead frame is shown in FIG.
It has a structure of.

By using the two-stage mold structure in this way, the effective utilization rate of the resin is further improved.

The invention made by the inventor of the present invention has been specifically described above based on the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, as shown in FIGS.
FIG. 17 shows a structural diagram in which cavities are arranged in an arc shape around the pot 26, and each gate is located at each part of the cavity. FIG. 18 is a structural diagram in which the lead frame 1 having one pot array as a basic pattern for the four cavities shown in FIG. 1 is arranged in a matrix on one frame. If the molding is performed using a mold, the resin material can be reduced and the productivity can be improved.

[0037]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

(1) By arranging the pot in the lead frame, the distance from the pot to the cavity is short, so it is possible to reduce the amount of resin that is wasted in the conventional mold structure, such as culls and runners. Becomes

(2) In the conventional mold structure, the pot,
The runner was independent from the lead frame,
By constructing the pot inside the lead frame 1 without providing a runner as in the present invention, space efficiency is improved and productivity can be improved.

(3) Since the resin is injected from the pot into a plurality of cavities arranged radially, the resin injection pressure and the resin injection amount into the respective cavities are made uniform, and the yield of thin packages can be improved.

(4) According to the lead frame of the present invention,
By providing a projecting hole in the frame in the vicinity of the cull portion so that a part of the frame does not overlap the cut portion of the cull portion resin, the lead frame and the cull portion resin can be easily cut.

(5) By making the thickness of the cull 9 thinner than that of the package body 16 as shown in FIGS. 8 to 9,
Since the molded products (package body 16) can be directly stacked without using a dedicated jig, the stacking becomes easy.

[Brief description of drawings]

FIG. 1 is a top view of a lead frame applied to an assembly of a resin mold type semiconductor device according to the present invention.

FIG. 2 is a top view showing a semiconductor device formation region within a dashed-dotted line frame in FIG.

FIG. 3 is a cross-sectional view corresponding to the section AA of FIG. 1 in the molded product according to the present invention.

FIG. 4 is a front sectional view of a molding apparatus used in an example of the present invention.

FIG. 5 is a front sectional view of a molding apparatus used in an example of the present invention.

FIG. 6 is a front sectional view of a molding apparatus used in an example of the present invention.

FIG. 7 is a top view showing a layout of a mold used in an example of the present invention.

FIG. 8 is a side view of a product after completion of molding according to the present invention.

FIG. 9 is a side view showing a stacked form of products after completion of molding according to the present invention.

FIG. 10 is an enlarged top view of a B part in FIG.

FIG. 11 FIG. 1 in a product after molding according to the present invention.
It is a cut sectional view corresponding to CC cross section of 0.

FIG. 12 FIG. 1 of the molded product according to the present invention.
It is a cutting cross section corresponding to DD cross section of 0.

FIG. 13 is a front sectional view of a molding apparatus used in another embodiment of the present invention.

FIG. 14 is a front sectional view of a molding apparatus used in another embodiment of the present invention.

FIG. 15 is a front sectional view of a molding apparatus used in another embodiment of the present invention.

FIG. 16 is a front sectional view of a molding apparatus used in another embodiment of the present invention.

FIG. 17 is a schematic top view showing the structure of another embodiment according to the present invention.

FIG. 18 is a schematic top view showing the structure of another embodiment according to the present invention.

[Explanation of symbols]

 1 ... Lead frame 2 ... Inner lead 3 ... Outer lead 4 ... Dam 5 ... Resin tablet hole 5a, 5b ... Projection hole 6 ... Slit 7, 8 ... Hole 9 ... Cull portion 10 ... Flow cavity portion 11 ... Communication passage portion 12 ... Gate 13 ... Mold line 14 ... Guide Hole 15 ... Slit 16 ... Package body 17 ... Resin 18 ... Groove 19 ... Stress absorption hole 20 ... Cavity 21 ... Assembly complete lead frame 22・ ・ ・ Upper mold 23 ・ ・ ・ Lower mold 24 ・ ・ ・ Plunger 25 ・ ・ ・ ・ Resin tablet 26 ・ ・ ・ ・ Pot 27 ・ ・ ・ ・ ・ ・ Medium dies 28 ・ ・ ・ ・ ・ ・ Lead frame 29 ... Mold complete package 30 ... Tab 31 .... semiconductor pellet 32 ... tab suspension leads 33 .... bonding pads 34 ... bonding wire 35 ... crack (crack) 36 ... lead frame mounting portion

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location H01L 23/50 K // B29L 31:34 (72) Inventor Kazuo Shimizu Kamimizumoto-cho, Kodaira-shi, Tokyo 5-20-1 Incorporated company Hitachi Ltd. Semiconductor Division (72) Inventor Katsuo Arai 5-201-1 Kamimizuhonmachi, Kodaira-shi, Tokyo Incorporated Hitachi Ltd Semiconductor Division (72) Inventor Takumi Soba 5-20-1 Kamimizuhonmachi, Kodaira-shi, Tokyo Inside the Semiconductor Division, Hitachi, Ltd. (72) Inventor Yasuhiro Koyama 5-20-1 Kamimizuhoncho, Kodaira-shi, Tokyo Within Hitachi Semiconductor Division ( 72) Inventor Mitsuo Togawa 5-20-1 Kamimizuhoncho, Kodaira-shi, Tokyo Incorporated company Hitachi Ltd. Semiconductor Division

Claims (6)

[Claims] 1. A plurality of semiconductor device forming regions, each including a semiconductor supporting portion, a plurality of inner leads whose ends are provided in the vicinity of the semiconductor supporting portion, and a plurality of outer leads connected to the inner leads, are provided. And a step of preparing a lead frame having a hole in which a resin tablet provided in the vicinity of the semiconductor device forming region is located; a step of attaching a semiconductor element having a bonding pad to the semiconductor supporting portion; A step of electrically connecting the pad and the inner lead with a wire, and thereafter forming a plurality of cavities corresponding to each of the semiconductor device forming regions of the lead frame, and a hole in which the resin tablet of the lead frame is located A step of clamping with a mold in which the pot space is positioned in the pot, and A resin encapsulation method for an electronic device, comprising inserting a tablet, injecting a resin into the cavity, and encapsulating the semiconductor element, the inner lead and the wire in the semiconductor device formation region. 2. The method for resin encapsulation of an electronic device according to claim 1, wherein the lead frame is used and resin is poured into the semiconductor device formation region through a gate connected to the pot and resin encapsulation is performed. 3. The resin sealing method for an electronic device according to claim 1, wherein the resin is a low hygroscopic resin. 4. The hole is arranged in a plurality, and is resin-sealed by using the lead frame having a plurality of semiconductor device formation regions located around each hole. Method for resin encapsulation of electronic device of. 5. A semiconductor device forming region having a semiconductor supporting portion, a plurality of inner leads whose ends are provided in the vicinity of the semiconductor supporting portion, and a plurality of outer leads connected to the inner leads as one unit. And a hole in which a resin tablet provided in the vicinity of the semiconductor device forming region is located. 6. The lead frame according to claim 5, wherein the lead frame is made of a material selected from a Fe.Ni-based alloy or a Cu-based alloy.