JP2001217370A - Lead frame and resin sealed device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lead frame and a resin sealed device in which residual resin is removed without causing any cracking in the resin remaining on a runner by the impact of a punch. SOLUTION: A lead frame 12 is provided with cut holes 19 and an upper die 1 is provided with recesses 3 facing the cut holes 19, at the time of resin sealing, so that no protrusion, projecting from the cut hole 19 of the lead frame 12 and adhering to the lead frame 12 after resin sealing, is formed on the resin mass of a runner 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molded area including an island on which a semiconductor chip is mounted and a plurality of leads derived from the periphery of the island are arranged vertically and horizontally on a single metal plate. Lead frame formed and said lead frame
The present invention relates to a resin sealing device for sealing a semiconductor chip mounted on a do frame with a resin and removing resin burrs of the lead frame sealed with the resin.

[0002]

2. Description of the Related Art Conventionally, a lead frame of this type is formed by arranging islands on which a semiconductor chip is mounted and sealed with a resin on a single metal plate in a matrix and pressing or etching. . In particular, this lead frame has been used in a semiconductor device of a QFP type package from the viewpoint of high productivity.

FIG. 7 is a flow chart for explaining an example of a process of assembling a semiconductor chip into a matrix type lead frame. The assembly of the semiconductor device of this QFP package
As shown in FIG. 7, first, a semiconductor chip is mounted on an island of a lead frame, and an electrode pad of the semiconductor chip and an internal lead of the lead frame are wired.
A resin-sealed formation region including a semiconductor chip, a wire, and a lead is sealed with a resin. Unnecessary runner portions and resin burrs remaining in the gate portion in the resin-sealed resin-sealed formation region are punched and removed with a punch.

[0004] However, in this assembling process, resin dust generated at the time of cutting the tie bar after the outer plating is generated.
Dropping on the cutting die or lead forming die, even damaging the die of the tie bar cutting die, or resin dust sticking to the forming punch of the lead forming die, causing poor contact of the lead. That was the problem.

FIG. 8 is a flow chart for explaining another example of the process of assembling a semiconductor chip into a matrix type lead frame. Therefore, as shown in FIG. 8, by performing the tie-bar cutting step before the exterior plating step, even if resin dust adheres to the lead, the resin dust attached in the exterior plating step is eliminated by removing the resin waste. Was.

[0006]

FIGS. 9A and 9B are views showing the state of a lead frame after resin sealing for explaining the problem. However, performing the tie-bar cutting before the outer plating causes a new problem.

In the resin encapsulation in the encapsulation step of FIG. 8, when the resin encapsulation forming area including the semiconductor chip on the lead frame is encapsulated with resin, as shown in FIG. The resin body 13 molded in the cavities on both sides of the mold runner, the remaining 20b on the runner in which the resin filled in the runner is molded, and the flow path of the molten resin from the runner to the gate. The gate residue 20a formed in the step (1) is formed in a state of being attached to the lead frame (12).

As described above, the remaining gate 20a and the remaining runner 2 are connected to the resin body 13 and adhere to the lead frame 12.
In order to remove Ob from the lead frame 12, a resin deburring mold having punches 14 and 15 was used. The remaining gate 20a punched by the punch 15 is easily removed because the constricted portion of the gate is broken.

However, the remaining 20b on the runner is cracked by the impact force of the punch 14 at the resin portion on the side wall of the resin holding hole of the lead frame 12, as shown in FIG. Then, they are separated into large resin blocks separated by the cracks 22 and fall downward. However, the circular resin waste 21 remains adhered to the inner wall of the resin holding hole provided for preventing deformation of the lead frame on the long runner. The resin dust 21 is peeled off by the impact when the lead frame is transported to the tie-bar cutting die, falls downward, and is placed on the die of the tie-bar cutting die. And the tie bar
When the cutting punch descends, there are problems that the lead is broken by resin dust and the blade of an expensive die is damaged.

Accordingly, an object of the present invention is to provide a lead frame and a resin sealing device capable of removing the resin residue without causing cracks in the resin residue on the runner due to the impact of the punch.

[0011]

A first feature of the present invention is as follows.
A plurality of rectangular resin sealing formation regions including an island on which the semiconductor chip is mounted, a plurality of leads extending outward from the periphery of the island, and a tie connecting the leads to one another are provided. In a lead frame formed in a metal plate vertically and horizontally, a strip having a strip-shaped notch hole extending in a horizontal direction between adjacent corners of the resin sealing formation region arranged in two rows in a vertical direction. -Do frame. Further, it is desirable that the end of the notch hole has a circular shape.

[0012] A second feature of the present invention is the above-mentioned lead frame.
And a recess forming the upper half of the cavity and a part of the molten resin flow path from the passage hole of the lead frame to the gate into which the molten resin flows. Upper mold 1, a runner into which the molten resin flows, and a sub-runner derived from the runner and communicating with the gate.
A resin sealing device, comprising: a resin molding die comprising: a lower mold in which a recess forming the lower half of the cavity is formed. In addition, it is preferable that the projection has a projection projecting from the bottom of the depression and having a height lower than the depth of the depression.
Further, it is desirable to have a piece member in which the recess is formed and which can be attached to and detached from the upper mold.

[0013] The most desirable mode is that the lead frame is formed by a resin mold which is the second feature of the present invention.
A first punch for punching out a resin projecting member formed by the recess in which the resin sealing formation region of the system is sealed with the resin, and a gate resin residue formed by the sub-runner reaching the gate. The present invention is to provide a resin deburring mold including a second punch to be punched and dropped.

[0014]

Next, the present invention will be described with reference to the drawings.

FIGS. 1A and 1B are plan views of a lead frame placed on a lower mold for explaining a lead frame and a resin sealing device according to an embodiment of the present invention. It is a figure and AA sectional arrow view. As shown in FIG. 1, the lead frame 12 of the matrix type has a semiconductor chip 24.
Are formed vertically and horizontally on a single metal plate, including an island 21 on which is mounted and a plurality of leads 22 extending outward from the periphery of the island 21.

Further, the lead frame 12 is adjacent to the lead frame 12 in the longitudinal direction of the paper surface, in addition to the passage hole 18 for pouring the molten resin into the gate 5 of the cavity 4 of the mold in which the resin body is molded. A rectangular cutout hole 19 extending horizontally between the corners of the resin sealing formation region 12a is provided. The end of the notch 19 is desirably circular. The notch 19 plays a role of forming a projection described later.

On the other hand, the semiconductor chip 24 is
As shown in FIG. 1 (b), a resin sealing mold for mounting the lead frame 12 mounted and wired on the lower mold 2 and sealing the resin sealing formation region 12a with a resin is shown in FIG. The recess 3 facing the notch hole 19 of the frame 12, the recess forming the upper half of the cavity 4, and a part of the flow path of the molten resin to the gate 5 into which the molten resin flows from the passage hole 18. Is formed, a runner 16 into which molten resin flows from a pot (not shown), a subrunner 17 derived from the runner 16 and communicating with the gate 5, and a recess forming the lower half of the cavity 4. Is formed.

Next, the operation of resin sealing using the lead frame of FIG. 1 will be described. First, the lead frame 12 in which the semiconductor chip 24 is mounted on the island 21
Is placed on the lower mold 2. Then, after closing the mold, the molten resin is poured from the pot into the runner 16. The molten resin flows into the runner 16 from left to right on the plane of the paper, and when it reaches the foremost runner 16, the pressure of the molten resin increases. As the pressure increases, the molten resin enters through the notch 19, and the molten resin is removed. At the same time as the cavity 3 is filled, the cavity 4 is filled from the gate 5 through the sub-runner 17.

FIG. 2 is a perspective view showing a part of the lead frame after resin sealing. The lead frame 12 which is resin-sealed by the above-described resin-sealing mold and separated from the mold is shown in FIG.
As shown in FIG. 7, the protrusion 20c formed by the depression 3 integrated with the rest 20b on the runner separated from the runner 16 and the mold from the flow path of the molten resin from the gate 5 to the sub-runner 17. The remaining gate 20a and this gate
The resin body 13 connected to the rest 20a and separated from the cavity 4 is adhered to the front and back surfaces of the lead frame 12.

Although not shown in the drawings, the resin body 1
The lead 22 and the tie bar 23 are exposed from the resin body 13 from the peripheral portion 3. The lower surface of the lead 22 extending from the side surface of the adjacent resin body 13 is attached to the rest 20b on the runner away from the projection 20c. However, the adhesion strength is weak, and it can be easily peeled off by the impact of a punch described later.

FIG. 3 is a view for explaining a resin burr removing mold for removing the protrusion, the remaining gate and the remaining resin on the runner of FIG. This mold for removing resin burrs has a resin body 1
3, a lower die 6 on which a lead frame 12 is placed and which has a hole 7;
It comprises a punch 14 for hitting 0c, and a punch 15 for hitting the remaining gate 20a formed by the sub-runner 17 leading to the gate 5 in FIG.

Next, the operation of removing the resin burr by the resin burr removing mold will be described. Resin sealing formation region 12a
The lead frame 12 sealed with resin is placed on the lower die 6 by a transfer device (not shown). Next, the upper die is lowered, and the punch 14 hits the projection 20c and the punch 15 hits the remaining gate 20a.

As a result, the projection 20c separates from the lead frame 12 and falls downward through the through hole 7 together with the rest 20b on the runner. On the other hand, the remaining gate 20a hit by the punch 15 breaks at the constricted gate 5 and falls downward through the through hole 7. Here, as shown in FIG. 2, the corner where the projection 20c and the remaining 20b on the runner contact each other has a radius, so that the notch effect does not occur in this portion and cracks occur as in the related art. Does not occur.

The lead frame from which the resin burrs have been completely removed in this manner is sent to a tie-cutting die by a transfer device, and the tie connecting the leads is cut. By providing the projections 20c in this manner, the resin burr can be completely removed without generating cracks.
The resin chips do not fall onto the die of the tie-bar cutting die, and there is no dent on the lead, which has conventionally occurred.

FIGS. 4A and 4B are diagrams for explaining the optimum design of the projection. As described above, the shape of the projection 20c provided for removing the remaining portion 20b on the runner without causing cracks is desirably a strip shape and its end is preferably a circular shape.

The dimensions for determining the shape are L1, W1, and H1, as shown in FIG.
When the dimensions L2 and W2 of the notch holes 19 are set, for example, in setting these dimensions, it is necessary that the relative displacement between the upper die and the lower die be within 0.05 mm including the clearance. is there. L1 at this time is smaller than L2 by 0.025 mm. Further, the width W1 of the projection 20c is also smaller by 0.025 mm than the width of the notch hole 19.

On the other hand, FIG. 1 shows the height H1 of the projection 20c.
The depth of engraving of the recess 3 of the lead frame 1
2 is to be deeper than the thickness. For example, if the thickness of the lead frame 12 is 0.15 mm, a depth of about 0.2 mm is required including the draft to facilitate detachment from the mold. In short, it is only necessary to give the resin strength around the protruding portion 20c so that cracks do not occur when punching with a punch.

In order to further increase the strength of the projection 20c, increasing the height H1 only increases the amount of resin used, and is not necessarily a cost-effective method. Rather, the protrusion 20c and the remaining 2 on the runner
It is desirable to provide an arc or a surface at the connecting portion with 0b. In order to provide the arc or the inclined surface, the entrance portion of the upper mold cavity 3 may be chamfered or formed in an arc shape. Note that the actual volume of the projection 20c is about 0.1 cubic centimeter, and the amount of resin used per encapsulation is about 0.2 g, which is within the range of error with respect to the entire amount used.

FIG. 5 is a view showing a lead frame sealed with resin by a modified example of the upper die. In this resin-sealing mold, the depression 3 in FIG. 1 is provided with a projection projecting from the bottom and having a height lower than the depth of the depression 3. As a result, a recess 20d is formed in the protrusion 20c of FIG. Other than that, it is the same as the resin sealing mold of FIG.

By providing the protruding portion in the recess 3, as shown in FIG. 5, a recess 20d is formed in the protruding portion 20c, and the amount of resin used can be reduced accordingly. Especially Lee
As the do frame 12 becomes larger and the number of the dents 3 increases, the amount of resin used for the dents 3 cannot be ignored, and thus the protrusions are provided in the dents 3 to reduce the amount of resin consumed. Is desirable.

FIG. 6 is a sectional view of a part of the upper die showing a modification of the upper die of FIG. The depression 3 of the upper die 1 of FIG. 1 is manufactured by directly engraving the surface of the upper die. However, when the size of the recess 3 is changed due to the change of the lead frame, the upper mold 1
Re-producing a large amount of man-hours and costs is required.
Therefore, in the present mold, as shown in FIG. 6, a piece 8 having a depression 3 is separately manufactured as a single piece, and the piece 8 is attached to the upper mold 10 of the mold.
Can be attached and detached.

The block 8 is made of tool steel of the same material as that of the upper die 10, is fitted in advance in a recess of the upper die 10, and is fixed with a flat head screw 9 so as not to be displaced. Further, instead of the flathead screw 9, a hanging bolt may be used, and the piece 8 may be dug down from above the upper die 1 and fixed to the upper die 1 with the hanging bolt.

[0033]

As described above, according to the present invention, the lead frame is formed so that the protrusion protruding from the lead frame is formed on the resin mass adhering to the lead frame after the resin sealing. -By providing a cutout hole and a recess facing the cutout hole in the upper die, the resin mass is punched out with a punch without generating cracks at the boundary between the lead frame and the resin mass. Can be removed from the
There is no dropping of resin dust on the tie-bar cutting die, and there is an effect that defects due to dents on the lead are reduced and the yield of quality is improved.

In addition, there is no dropping of the resin waste to the die of the tie-bar cutting die, the damage of the die cutting edge is eliminated, the life of the die is prolonged, and the facility and operation costs can be greatly reduced. is there.

[Brief description of the drawings]

FIG. 1 is a plan view of a lead frame placed on a lower mold and a cross-sectional view taken along a line AA for explaining a lead frame and a resin sealing device according to an embodiment of the present invention. .

FIG. 2 is a perspective view extracting and showing a part of a lead frame after resin sealing.

FIG. 3 is a view for explaining a resin burr removing mold for removing a protrusion, a gate residue, and a resin remaining on a runner of FIG. 2;

FIG. 4 is a diagram for explaining an optimal design of a protrusion.

FIG. 5 is a view showing a lead frame which is sealed with a resin by a modified example of the depression of the upper die.

FIG. 6 is a partial cross-sectional view of an upper mold showing a modification of the upper mold shown in FIG. 1;

FIG. 7 is a flowchart illustrating an example of a process of assembling a semiconductor chip into a matrix-type lead frame.

FIG. 8 is a flow chart for explaining another example of a process of assembling a semiconductor chip into a matrix type lead frame.

FIG. 9 is a view showing a state of a lead frame after resin sealing for explaining a problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 10 Upper die 2, 6 Lower die 3 Depression 4 Cavity 5 Gate 7 Drilled hole 8 Piece 9 Countersunk screw 12 Lead frame 12a Resin sealing formation area 13 Resin body 14, 15 Punch 16 Runner 17 Subrunner -18 Passing hole 19 Notch hole 20a Gate remaining 20b Remaining on runner 20c Projection

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/56 H01L 21/56 DH // B29L 31:34 B29L 31:34 F term (Reference) 4F202 AH36 AH37 AM32 AM33 CA12 CB01 CB17 CK02 CK35 CK81 CK84 CK86 CQ01 4F206 AH36 AH37 AM32 AM33 JA07 JB17 JF05 JQ81 5F061 AA01 BA01 CA21 DA04 DD12 EA02 EA03 EA13 5F067 AA09 AB03 BA01 DE02 DE19

Claims (6)

[Claims] 1. A plurality of square resin moldings including an island on which a semiconductor chip is mounted, a plurality of leads extending outward from the periphery of the island, and a tie bar connecting the leads. In a lead frame in which regions are formed vertically and horizontally on a single metal plate, strip-like cuts extending in the horizontal direction are provided between adjacent corners of the resin sealing formation regions arranged in two rows in the vertical direction. A lead frame having a notch. 2. The lead frame according to claim 1, wherein an end of said notch hole is circular. 3. The lead according to claim 1 or 2,
The recess facing the notch hole of the dove frame, the recess forming the upper half of the cavity, and a part of the molten resin flow path from the passage hole of the lead frame to the gate into which the molten resin flows are formed. An upper mold 1 to be formed, a lower mold having a runner into which the molten resin flows, a subrunner derived from the runner and communicating with the gate, and a recess forming the lower half of the cavity are formed. A resin sealing device, comprising: 4. The resin sealing device according to claim 3, wherein the resin sealing device has a protrusion projecting from a bottom of the depression and having a height lower than a depth of the depression. 5. The resin sealing device according to claim 3, wherein the recess is formed and a piece member is attached to and detachable from the upper mold. 6. A first punch for punching out a resin projection member formed by the recess, wherein the resin sealing formation region of the lead frame is resin sealed by the resin sealing mold according to claim 3. And a second step of punching and removing gate resin residue formed by the sub-runner to the gate.
The resin sealing device according to claim 3, further comprising a resin deburring mold including the punch.