JP2962405B2 - 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 of manufacturing a semiconductor device, and more particularly to a method of assembling a semiconductor device in which a resin remaining in a resin pool at the time of resin sealing is left on a lead frame and removed in an external lead processing step. Things.

[0002]

2. Description of the Related Art In a resin molding of a thin and large package represented by a QFP (quad flat package), a resin molding method of an upper gate and a lower gate is often used instead of a conventional lower gate. In this type of sealing die, a resin reservoir may be provided in front of the gate on the side where no runner exists, and resin may be injected into the cavity through the resin reservoir. FIG. 6 is a cross-sectional view for explaining the resin sealing step of this method.

A lead frame 1 on which a semiconductor chip 13 is mounted is sandwiched between a lower mold 21 and an upper mold 26. The lower mold 21 has a pot 22, a runner 23, a lower gate 2
4 and a lower cavity 25 are formed.
6, an upper resin reservoir 27, an upper gate 28, and an upper cavity 29 are formed. The lead frame 1 is formed with a resin passage hole 2a for passing the resin at a position corresponding to the upper resin reservoir 27.

When the resin 15 held in the pot 22 is pushed up by a plunger (not shown), the resin passes through a runner 23 and a part flows into a lower cavity 25 through a lower gate 24. Further, a part enters the upper resin reservoir 27 through the resin passage hole 2a of the lead frame, and flows into the upper cavity 29 via the upper gate 28 therefrom.
After heating in this state for a predetermined time, the lead frame is removed from the mold. Thereafter, a so-called gate break is performed to remove the runner resin and the resin pool resin.

[0005] Thereafter, the tie bars of the lead frame are cut. In this step, if the resin in the resin pool is not removed or is not removed in the gate break, it is removed. Next, burrs are removed using a burr removing means such as a water jet. Next, plating is performed, and the external leads are cut to a predetermined length. Finally, the external lead is formed into a predetermined shape, and the suspension lead of the lead frame is cut to separate the semiconductor device from the frame portion of the lead frame. Conventionally, in order to make it easier to separate and remove the resin pool resin from the semiconductor device, FIG.
As shown in (2), the diameter of the resin passage hole 2a of the lead frame is larger than that of the resin reservoir 27.

When resin sealing is performed by the lower gate method, unlike the case of the upper and lower gate methods, no resin passage hole is provided in the lead frame.
Japanese Patent Application Laid-Open No. 4 (1999) -1999 proposes providing a through hole at a position corresponding to a runner of a lead frame. FIG. 7 (a)
(A) to (c) are sectional views in the order of steps showing a method of assembling a semiconductor device proposed in this publication. In this assembly method,
As shown in FIG. 7A, a lead frame 1 provided with a through hole 2b at a position where a runner resin 10a is formed,
The semiconductor chip 13 is sealed with the sealing resin part 9 by using a sealing mold in which a narrowed part 11 a provided to fold the runner part resin 10 a at the end surface of the lead frame is formed. At this time, the unnecessary runner resin 10a is formed outside the lower gate constriction 12b. afterwards,
As shown in FIG. 7 (b), the runner resin 10a is folded at the narrowed portion 11a to remove the runner resin on the cull side.
At this time, a part of the runner resin 10a remains on the lead frame. Then, in the step of forming the external lead, as shown in FIG. 7C, when the external lead 6 is bent and the semiconductor device is separated from the lead frame, the runner resin 10a left on the lead frame is removed. It is separated by the lower gate constriction 12b and removed together with the frame portion of the lead frame 1.

In this assembling method, a portion of the resin of the runner portion on the lead frame is left on the lead frame side at the time of a gate break operation. This prevents "gate resin gouging" and "external lead shape abnormality" caused by the resin chipping.

[0008]

In the conventional method of assembling the upper and lower gates shown in FIG. 6, it is difficult to completely remove the pool resin at the time of gate break, and it is necessary to remove the resin in the tie bar cutting step. However, since the pool resin is not firmly fixed to the lead frame, it often falls during transportation, during a processing step, or the like. Then, the dropped resin in the pool portion comes into contact with the external lead to give an undesired bending or to be caught in a tie-bar cutting die or the like, causing damage to the devices.

Recently, a method of arranging a tie bar at a position longer than a necessary length of an external lead (distant tie bar method) has been adopted. In this case, a tie bar cutting step itself is performed. Because it ’s gone,
The pool resin removed in this step is transported in an unstable state to a further step, and the above-described inconvenience is diffused to the subsequent step. This can be avoided by providing a separate pool resin removal step before the deburring step, but even in this case, the equipment may be damaged or the leads may be deformed by the drop before the removal step described above. Sex remains.

On the other hand, in the lower gate type shown in FIG. 7, although the adhesion between the runner resin and the lead frame is enhanced, the adhesion is enhanced by the side portions of the through holes provided in the lead frame. And the large runner resin is left on the lead frame, so the fixation is not sufficient, and when the external force is applied to the runner resin in the deburring process or the plating process of the external lead, it falls. This is not a solution to the above-described problem of the prior art of the upper and lower gate method.

Further, in the above-described conventional example of the lower gate system, the runner resin is left even on the end surface of the lead frame, so that the lead frame can be transported by sliding on the transport rail in an assembly process after resin sealing. In addition, a pick-and-place mechanism for lifting, transferring, and lowering is required, and there has been a problem that the mechanism of the manufacturing apparatus is complicated and the cost is increased.

Accordingly, the problem to be solved by the present invention is as follows:
Secondly, it is intended to prevent the pool resin from dropping during the assembling process and to prevent damage to the equipment and abnormal shape of the external lead caused by the drop. Is to eliminate the necessity of providing a special step of removing the resin in the pool portion.

[0013]

The above-mentioned objects are achieved by (a) providing a resin reservoir in each of the upper and lower molds, and (b) forming a resin passage hole in the lead frame having a shape smaller than the planar shape of the resin reservoir of the mold. The problem can be solved by opening the hole, and (c) cutting the suspension lead of the lead frame so that the resin of the pool remains on the frame side when the semiconductor device is cut out from the frame portion of the lead frame.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a method of manufacturing a semiconductor device according to the present invention, a resin reservoir is provided in front of a gate of an upper and lower mold, and a resin reservoir is provided between the upper and lower molds. A step of sandwiching a lead frame having a resin passage hole having a planar shape smaller than at least one of the resin reservoirs at a position to be filled, injecting a resin into a cavity through a runner and the resin reservoir, and performing resin sealing; and a step of resin reservoir resin to remove unnecessary resin otherwise in the remain in the lead frame from the lead frame, a step of cutting the semiconductor device as resin reservoir resin on the outer frame portion of the lead frame remains, It is characterized by including. Then, preferably, the external lead is cut before the first step, and the external lead is simultaneously formed in the second step. The resin of the runner portion including the cull (the resin of the pot portion) is removed at the stage where the gate break has been performed conventionally (this process is called a runner break in the present specification).

As described above, in the method of manufacturing a semiconductor device according to the present invention, the upper and lower molds are provided with the resin reservoir,
Further, since a resin passage hole having a planar shape smaller than the resin reservoir is provided at a position corresponding to the resin reservoir of the lead frame, the resin reservoir resin is formed so as to bite into the lead frame. Therefore, the pool resin is securely left on the lead frame side during the runner break process, and drops from the lead frame in each step such as deburring by water jet, plating, cutting of external leads, and the transporting process therebetween. Will not be done.

Since the resin in the reservoir is removed from the semiconductor device when the suspension lead is cut, a step only for removing the resin in the reservoir needs to be provided when the remote tie bar method is employed. Is gone. In addition, in each step after the runner break step, only a small pool resin adheres to the outside of the gate,
Since the runner resin does not remain in the outer frame portion of the lead frame, the conventional simple method can be employed for transportation and other handling of the lead frame.

[0017]

Next, embodiments of the present invention will be described with reference to the drawings. [First Embodiment] FIGS. 1 to 4 are views for explaining a first embodiment of the present invention. FIG. 1 is a plan view of a lead frame to be used, and FIG. FIG. 3 is a plan view of the lead frame after resin sealing as viewed from below. Also, FIG.
FIG. 4 is a cross-sectional view showing each step in a cross-sectional view of FIG.
4A is a cross-sectional view after resin sealing, FIG. 4B is a cross-sectional view after runner break, and FIG. 4C is a cross-sectional view showing a state where the semiconductor device is separated from the frame portion of the lead frame.

The lead frame used in this embodiment is shown in FIG.
As shown in the figure, a die pad 3 supported from all sides by suspension leads 4 is provided at the center, and from the periphery thereof, internal leads 5 extend outward and are connected to external leads 6. I have. The external leads 6 are connected by a tie bar 7 that prevents the resin from flowing when the resin is sealed. The tip of the external lead 6 is connected by an external lead connecting bar 6a.
a is connected to the frame part by the connector 1a.
Here, as shown in FIG. 4A, the length of the suspension lead 4 is smaller than the dimension of the die pad 3 and the semiconductor chip 13 during resin sealing.
Are depressed so that the upper dimension of the upper part is substantially equal to the upper part. And near the base of one suspension lead 4,
A resin passage hole 2 is provided corresponding to the resin pool of the sealing mold, and a pool resin is formed in this portion after resin sealing.

After the semiconductor chip 13 is mounted on the die pad 3 of the lead frame, and the semiconductor chip 13 and the internal lead 5 are connected by using a bonding wire, resin sealing is performed. Of the dies used for resin sealing, the lower die has an aperture formed near the gate of the runner, thereby forming a resin reservoir also in the lower die. As shown in FIG. 4A, the semiconductor chip 1
An upper pool resin 8a and a lower pool resin 8b are formed between the sealing resin section 9 for sealing 3 and the runner section resin 10. The resin passage hole 2 formed in the lead frame 1 is formed narrower than the resin reservoir formed in the upper and lower molds. A constriction 11 is formed between the lower pool resin 8b and the runner resin 10 in correspondence with the "diaphragm" formed in the lower mold, and the pool resins 8a and 8b and the sealing resin 9 are connected to each other. Between them, an upper gate constriction 12a and a lower gate constriction 12b are formed corresponding to the upper and lower gates of the mold.

After the resin sealing step, a runner break is performed to remove the runner resin 10 including cull.
Constriction 11 between runner part resin 10 and pool part resin 8b
Is formed, and the pool resins 8a and 8b bite into the lead frame and are firmly fixed. Therefore, the runner resin 10 is broken by the constriction 11 and easily runs from the lead frame 1 and the pool resins 8a and 8b. Separated.

Thereafter, the tie bar 7 is cut, and the remaining dam resin and other burrs are removed by a high-pressure water jet. Next, the external leads 6 are plated, and then the external leads 6 are cut to a predetermined length. During this time, the pool resins 8a and 8b are stably fixed to the lead frame. Next, as shown in FIG. 4 (c), the semiconductor device is taken out of the lead frame by bending the external lead 6 and cutting the suspension lead 4 and the upper and lower gate constrictions 12a and 12b of the resin. Is completed. At this time, the pool resin 8a, 8b is left on the frame side of the lead frame, and is discarded while being attached to the lead frame.

As described above, since the pool resin bites into the lead frame and is firmly fixed, it does not drop in the process of transportation or processing after resin sealing, thereby causing damage to equipment and the like. Defects such as bending of external leads can be drastically reduced. Further, since the outer peripheral portion of the lead frame is not covered with the resin, it can be conveyed by the rails in the steps after the sealing as before.

In the above embodiment, the bending of the external lead is performed after the external lead is cut to a predetermined length.
First, the connecting body 1a is cut (see FIG. 1) in a state where the connection is made by a, and the external lead is bent in that state (at the same time, the pool resin is removed from the semiconductor device). The lead may be cut to a desired length. Instead of water jet, other means such as liquid honing and sublimation by laser beam irradiation can be used for deburring.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a diagram for explaining the second embodiment of the present invention, and is an enlarged plan view showing a dam resin portion and a tie bar portion of the lead frame 1 after resin sealing. The present embodiment relates to a case where a remote tie bar type lead frame is used. In the case of a normal lead frame, the distance L from the sealing resin portion 9 to the tie bar 7 is longer than the required length of the external lead. Although it is shortened (usually about 0.2 to 0.5 mm), in this embodiment, L is longer than the length after the external lead bending process (for example, if the required length of the external lead is 2 mm, L
Is about 2.2 mm).

As shown in FIG. 5, after resin sealing is performed using the same mold as in the first embodiment, the dam resin 14 is removed by a high-pressure water jet without cutting the tie bar. . At this time, since the pool resin is firmly fixed to the lead frame, the resin does not fall even if a water jet is applied. Next, the external leads 6 are plated, and the external leads 6 are cut to a predetermined length (for example, 2 mm). After that, the external lead 6 is bent, and at the same time, the hanging lead and the gate constriction portion of the resin are cut to take out the semiconductor device from the lead frame.

[0026]

As described above, in the method of manufacturing a semiconductor device according to the present invention, the upper and lower dies are provided with a resin reservoir, and the lead frame is smaller than the resin reservoir corresponding to the resin reservoir. Since resin sealing is performed by providing a resin passage hole with a planar shape and the resin in the reservoir is removed from the semiconductor device at the final stage of the assembling work, the resin in the reservoir can be cut into the lead frame and molded. This makes it possible to stably fix the pool resin to the lead frame during the assembling operation. Therefore, according to the present invention, it is possible to reliably prevent the pool resin from dropping, and it is possible to prevent damage to devices and undesired bending of the leads due to the drop. In addition, since the pool resin can be removed when the semiconductor device is taken out of the lead frame, when a remote tie bar type lead frame is used, there is no need to provide a separate step for removing the pool resin. , Workability can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view of a lead frame used in a first embodiment of the present invention.

FIG. 2 is a top view showing a state after resin sealing of the lead frame for explaining the first embodiment of the present invention.

FIG. 3 is a bottom view for explaining the first embodiment of the present invention, showing a state after resin sealing of the lead frame.

FIG. 4 is a sectional view in the order of steps for explaining the first embodiment of the present invention.

FIG. 5 is a plan view showing a state after the resin sealing of the lead frame for explaining the second embodiment of the present invention.

FIG. 6 is a cross-sectional view for explaining a conventional resin sealing step.

FIG. 7 is a sectional view in the order of steps for explaining a conventional example in the case of a lower gate method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lead frame 1a Connection body 2, 2a Resin passage hole 2b Through hole 3 Die pad 4 Suspension lead 5 Internal lead 6 External lead 6a External lead connection bar 7 Tie bar 8a Upper pool resin 8b Lower pool resin 9 Sealing resin section 10, REFERENCE SIGNS LIST 10a Runner portion resin 11 Constriction 11a Narrow portion 12a Upper gate constriction 12b Lower gate constriction 13 Semiconductor chip 14 Dam resin 15 Resin 21 Lower mold 22 Pot 23 Runner 24 Lower gate 25 Lower cavity 26 Upper mold 27 Upper resin reservoir 28 Upper gate 29 Upper cavity

Claims (5)

(57) [Claims] (1) A resin reservoir is provided before each of the gates of the upper and lower molds, and a resin reservoir is provided between the upper and lower molds.
A step of sandwiching a lead frame having a planar resin passage hole smaller than at least one resin reservoir at a position corresponding to the resin reservoir and injecting a resin into a cavity through a runner and the resin reservoir to perform resin sealing; If, (2) a step of sealing resin and the resin reservoir portion resin to remove unnecessary resin otherwise in the remain in the lead frame from the lead frame, (3) an outer frame portion in the resin reservoir resin of the lead frame And c. Cutting out the semiconductor device so as to remain. 2. The method of manufacturing a semiconductor device according to claim 1, wherein a lead frame having a distance from the resin sealing portion to the tie bar is longer than a necessary length of the external lead. 3. The method according to claim 1, wherein the step (2) is performed using a runner tree.
Remove grease from lead frame by runner break
Sub-steps, Deburring means such as high-pressure water injection
And a sub-step of removing burrs.
The method for manufacturing a semiconductor device according to claim 1. 4. The semiconductor according to claim 1, wherein the external lead is cut from the lead frame prior to the step (3), and the external lead is bent at the same time as the step (3). Device manufacturing method. 5. The method according to claim 1, wherein the step (3) is performed while the distal ends of the external leads are connected by a connecting bar, the external leads are bent, and then cut and separated into individual external leads. 2. The method of manufacturing a semiconductor device according to claim 1, wherein