JPH10340976A - Resin-sealed semiconductor device - Google Patents

Abstract

(57) [Problem] To provide a resin-sealed semiconductor device in which the inflow speed of molten mold resin over and under a semiconductor chip is made uniform, and voids, wire flows, pad shifts, and the like are prevented. SOLUTION: The resin-encapsulated semiconductor device of the present invention holds a peripheral portion of a lead frame 11 on which a semiconductor chip 12 is mounted in a central portion by an upper mold 1 and a lower mold 2, and forms the upper and lower molds. The semiconductor chip is resin-sealed by injecting and solidifying a mold resin 10 in a hot melt state through a gate 4 into a cavity 3 formed therebetween. A guide plate 14 is formed on the side close to the guide frame 14 and is inclined with respect to the rest of the lead frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resin-sealed semiconductor device in which a semiconductor chip is sealed with a resin.

[0002]

2. Description of the Related Art In a resin-encapsulated semiconductor device, a peripheral portion of a lead frame on which a semiconductor chip is mounted is sandwiched between an upper mold and a lower mold, and a cavity formed by the upper mold and the lower mold is formed in a cavity. It is formed by pouring a mold resin melted by heating from a gate and solidifying it. Incidentally, in the resin-sealed semiconductor device, when the structure of the lead frame, the mounting position of the semiconductor chip, and the like change, the state of the flow of the mold resin into the cavity changes in the mold resin sealing step. That is, the mold resin that has flowed into the cavity is divided into an upper side and a lower side of the semiconductor chip and flows into the cavity. Therefore, if the mounting position of the semiconductor chip is changed, the inflow speed of the mold resin may be different between the upper side and the lower side of the semiconductor chip even in the same cavity. As described above, if there is a difference in the flow of the mold resin between the upper side and the lower side in the same cavity, problems such as voids, wire flow, and pad shift occur.

FIG. 3 is a schematic sectional view showing a resin inflow state when a conventional lead frame is sealed with a resin by a transfer molding method. When resin sealing is performed by a transfer molding method using a conventional lead frame as shown in FIG. 3, the inflow speed of the lower mold resin of the semiconductor chip is higher than that of the upper mold resin of the semiconductor chip. If the inflow of the mold resin above and below the semiconductor chip is imbalanced, problems such as voids, wire flow, and pad shift occur.

For this reason, conventionally, the structure of the package has been designed in consideration of the inflow state of the mold resin in the resin sealing step. For example, in the case of a structure in which a semiconductor chip is mounted below the lead frame, when the semiconductor chip shrinks, the volume of the semiconductor chip is reduced, and as a result, the space below the cavity is widened, and the vertical flow inside the cavity is increased. Since the balance changed, the injection conditions were reviewed.

However, in recent years, along with the progress of thinning of the package, only the above-mentioned conventional technique makes the inflow speed of the mold resin on the upper side and the lower side of the semiconductor chip the same, and causes voids, wire flows, and pad shifts. It has become difficult to prevent such occurrences.

[0006] Japanese Patent Application Laid-Open No. Hei 6-37130 discloses that
A movable pin is provided in the cavity, and the insertion depth of the movable pin into the cavity is changed according to the progress of the injection of the mold resin, thereby preventing the semiconductor chip from moving up and down and allowing the mold resin to flow. Is disclosed.

[0007]

However, in the above method of providing a movable pin in the cavity, the mold resin leaks out of the gap between the movable pin and a through hole formed in a mold for fitting the movable pin. To prevent
There is a problem that high dimensional accuracy is required for manufacturing a mold and a movable pin, and the manufacturing cost increases. Further, there is a problem that a mark of a pin remains on a surface to be marked.

The present invention has been made in view of the above circumstances, and has as its object to provide a resin-sealed semiconductor device capable of controlling the flow of mold resin with a simple configuration.

[0009]

In order to solve the above-mentioned problems, a resin-encapsulated semiconductor device according to the present invention includes a lead frame on which a semiconductor chip is mounted, which is sandwiched between an upper mold and a lower mold. In a resin-encapsulated semiconductor device having a structure in which a mold resin in a molten state is injected through a gate into a cavity formed between the upper mold and the lower mold and is solidified, thereby sealing the semiconductor chip with a resin. A part of the lead frame sealed by the mold resin, wherein at least one member inclined with respect to another part of the lead frame is formed on a side close to the gate. Is what you do.

In order to solve the above-mentioned problems, a lead frame according to the present invention is a part which is sealed by a molding resin when resin sealing is performed by a transfer molding method, and includes an upper mold and a lower mold. At least one member that is inclined with respect to the other portion is formed near the gate through which the mold resin flows into the cavity formed therebetween.

According to the present invention, by forming a member inclined toward the other part of the lead frame on the side near the gate on the lead frame, the cavity of the mold resin can be formed in the molding resin sealing step. Since the inflow velocities of the semiconductor chips in the vertical direction can be made substantially the same, it is possible to suppress problems such as voids, wire flow, and pad shift.

Further, according to the present invention, the inclined member is sealed with the resin together with the semiconductor chip and the like, so that even if a mold having a normal dimensional accuracy is used as the mold in the transfer molding method, the molten mold resin is exposed to the outside. Do not leak.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 2 (A)
1 is a plan view showing a structure of a resin-sealed semiconductor device according to an embodiment of the present invention before resin sealing. In FIG. 2A, a semiconductor chip 12 is held behind a central portion of a lead frame 11 with a polyimide tape 13 interposed therebetween. The upper frame 111 shown in FIG. 2A of the lead frame 11 is formed with two arms 15 and 16, and the other ends of the two arms 15 and 16 are provided with arms. A guide plate 14 supported by the parts 15 and 16 is formed. This guide plate 14 is formed so as to be located in the vicinity of the gate when sealing with the mold resin.
As shown in (B), when the lead frame is viewed from a direction in which the guide plate can be seen on the right side, the guide plate rotates clockwise and is inclined with respect to the other parts of the lead frame. .

As shown in FIGS. 1 and 4, the mold used in the present embodiment comprises an upper mold 1 and a lower mold 2.
Further, a pot 21 for supplying molten resin into the cavity in a pair with a plunger (not shown), and a runner 22 serving as a passage for flowing the molten resin into the cavity.
And a gate 4 serving as an injection port for injecting the molten resin into the cavity.

FIG. 1A is a schematic cross-sectional view showing a state in which the structure shown in FIG. 2 before sealing with a molding resin is sandwiched between an upper mold 1 and a lower mold 2 by transfer molding. 2 corresponds to a section taken along the line AA ′ in the structure before sealing with the mold resin shown in FIG. As can be seen from FIG. 1A, in the present embodiment, the guide plate 14 is formed at a substantially intermediate position between the gate 4 and the semiconductor chip. The guide plate 14 is inclined with respect to the other parts of the lead frame so that the upper surface faces the gate 4 side. The guide plate of the present embodiment can be formed simultaneously with the lead frame by using a press die for forming a lead frame. As described above, the lead frame of the present embodiment does not require a special process for forming, and thus has a feature that it can be easily implemented. Note that it is also possible to form the flat lead frame by etching and form the guide plate 14 by pressing.

When resin molding is performed by the transfer molding method using the lead frame of this embodiment having the guide plate 14, the mold resin 10 in the cavity flows in as shown in FIGS. 1B to 1D. The molten mold resin 10 is injected into the cavity via the runner 22 and the gate 4 by the plunger and the pot 21. As shown in FIG. 1 (B), the mold resin 10 in the molten state flowing into the cavity 3 from the gate 4 hits the guide plate 14 and its flow is controlled. That is, the guide plate having the upper surface inclined toward the gate 4 suppresses the flow of the mold resin flowing into the lower side of the semiconductor chip 12, so that the guide frame is not provided with the guide plate. In comparison, the inflow to the lower side of the semiconductor chip is suppressed. Therefore, by appropriately designing the inclination angle and the size of the guide plate according to the semiconductor chip to be mounted and the lead frame, FIG.
As shown in (C) and (D), the inflow speeds of the mold resin on the upper side and the lower side of the semiconductor chip can be made substantially the same. Thus, using the lead frame of the present embodiment,
By performing resin sealing, the inflow speed of the mold resin above and below the semiconductor chip can be easily made equal, so that problems such as voids, wire flow, pad shift, etc. are less likely to occur, and the durability of the semiconductor device is reduced. -Reliability is improved. Note that the arms 15 and 16 for supporting the guide plate become unnecessary after resin sealing, so that when cutting the other leads,
At the same time, it is cut from the base of the resin. In the present embodiment, a mark when the arm is cut remains on the side surface of the package. However, since marking is usually not performed on this side surface, there is no problem even if a trace remains.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention. For example, in the above embodiment, the case where a rectangular guide plate is used has been described. However, the guide plate is not limited to this, and may be, for example, a circular shape, an elliptical shape, or the like.

The guide plate is not limited to a flat plate, but may be a shape using a curved surface such as a streamlined wing shape in cross section.

Further, in the above embodiment, the guide plate is
Although the case of supporting by the L-shaped arms of the book has been described, the guide plate may be fixed to the tips of a number of wide linear arms in order to increase rigidity.

In the above embodiment, the case where the upper surface of the guide plate is inclined toward the gate is described. However, depending on the structure of the cavity, the upper surface of the guide plate may be inclined so as to face the semiconductor chip. Further, the guide plate may be set upright with respect to other parts of the lead frame.

In addition, the shape and dimensions of the guide plate, the inclination angle with respect to the other parts of the lead frame, and the like are determined based on the structure of the lead frame, the mounting position of the semiconductor chip, the type of molding resin to be injected, and the like. An appropriate value is designed according to the result of the trial of resin sealing. The preferred embodiments have been described with reference to the accompanying drawings. However, the present invention is not limited to the above-described embodiments, and departs from the spirit and scope of the invention described in the appended claims. Without departing from the invention, various changes and modifications can be made by those skilled in the art.

[0022]

As described above, in the resin-encapsulated semiconductor device of the present invention, the guide plate inclined toward the other part of the lead frame is formed on the side of the lead frame close to the gate. In the molding resin encapsulation process, the inflow velocity of the semiconductor chip in the cavity of the heat-melted molding resin can be made equal in the vertical direction, so that problems such as voids, wire flow, and pad shift can occur. Occurrence can be suppressed.

In the resin-sealed semiconductor device of the present invention, the inclined guide plate is also resin-sealed together with the semiconductor chip and the like. The molten resin does not leak out.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view for explaining a mold resin sealing step of a resin-sealed semiconductor device according to one embodiment of the present invention.

FIG. 2A is a plan view showing a structure of a resin-sealed semiconductor device of the present embodiment immediately before a molding resin sealing step;
FIG. 2B is a sectional view taken along the line AA ′ of FIG.

FIG. 3 is a schematic cross-sectional view showing a resin inflow state when resin sealing is performed by a transfer molding method using a conventional lead frame.

FIG. 4 is a schematic plan view showing a state in which a mold resin flows into a cavity.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper mold 2 Lower mold 3 Cavity 4 Gate 10 Mold resin 11 Lead frame 12 Semiconductor chip 13 Polyimide tape 14 Guide plate 15, 16 Arm part 21 Pot 22 Runner 111 Frame part

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 23/50 H01L 23/50 G // B29L 31:34

Claims (11)

[Claims] 1. A lead frame on which a semiconductor chip is mounted is sandwiched between an upper mold and a lower mold, and is melted through a gate in a cavity formed between the upper mold and the lower mold. In a resin-encapsulated semiconductor device having a structure in which the semiconductor chip is resin-encapsulated by injecting and solidifying the mold resin, a part of the lead frame sealed by the mold resin, the side being close to the gate A resin-encapsulated semiconductor device, wherein at least one member inclined with respect to the other part of the lead frame is formed. 2. The resin-encapsulated semiconductor device according to claim 1, wherein an inclination angle between said member and another portion of said lead frame can be changed. 3. The resin according to claim 1, wherein the member is a flat plate held between tips of two support members extending from another portion of the lead frame. Sealed semiconductor device. 4. The mold resin flows into a cavity that is sealed by the mold resin when the resin is sealed by a transfer molding method and is formed between an upper mold and a lower mold. A lead frame, wherein at least one member inclined with respect to another portion is formed in the vicinity of a gate for making the lead frame. 5. The lead frame according to claim 4, wherein the inclined member is formed by using a press die like other parts. 6. The lead frame according to claim 4, wherein the inclined member is inclined with respect to another portion such that an upper surface thereof faces the gate side. 7. The lead frame according to claim 4, wherein said inclined member is formed at a substantially intermediate position between said gate and said semiconductor chip. 8. The lead frame according to claim 4, wherein said mold resin is a thermoplastic resin. 9. A member for adjusting the flow of the mold resin in the cavity at the time of performing the resin sealing, at least in a portion sealed by the mold resin when the resin is sealed by the transfer molding method. A lead frame, wherein one lead frame is formed. 10. A lead frame, comprising: a plurality of leads forming a common horizontal plane; and at least one member formed to be inclined with respect to the horizontal plane. 11. A semiconductor device comprising the lead frame according to claim 10.