JP2011108699A - Mold for manufacturing semiconductor device, method of manufacturing semiconductor device, and the semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold for manufacturing a semiconductor device preventing the back of a package from being warped by solving a problem of generation of a gap when packaging to a heat sink and a decrease on heat radiation properties caused by warpage generated in the package by shrinkage of resin occurring in curing of the sealing resin, and to provide a manufacturing method. <P>SOLUTION: In the mold for manufacturing a semiconductor device, the semiconductor package is formed by clamping a lead frame while being localized to the side of a second mold from the center in a thickness direction of a cavity and injecting the sealing resin into the cavity formed by putting together both of a first die for forming the front side of the semiconductor device and a second die for forming the rear side. In the mold for manufacturing the semiconductor device, a raised part is provided at an arbitrary position on a surface for forming the rear of the semiconductor device on an inner surface of the second die. The height is set according to the distance between a surface for forming the rear and the lead frame, and a rate of shrinkage in the resin. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a mold for manufacturing a full mold type semiconductor device used together with a heat sink for heat dissipation, a manufacturing method thereof, and a semiconductor device manufactured by the manufacturing method.

In general, a self-supporting semiconductor device is attached to a heat sink in order to efficiently dissipate heat generated by itself.

With respect to such a semiconductor device, a semiconductor device having a full mold type insulating semiconductor package that does not require an insulating sheet or the like when attached to a heat sink because of ease of handling at the time of device manufacture (for example, Patent Document 1) The number of cases where is used has increased in recent years.

JP 2002-151632 A

The heat dissipation efficiency of the semiconductor device attached to the heat sink is determined by the size of the heat sink to be used, and at the same time, the flatness of the contact surface between the semiconductor device and the heat sink is also greatly related. Therefore, a flat heat sink with no irregularities, twists, and warpage is usually prepared.

The flat shape of the heat sink is based on the premise that the surface of the semiconductor device attached to the mounting surface is in contact with the mounting surface at the same time. Many warpages have occurred on the back of the package.

In general, a semiconductor device having a full mold type insulated package has a lead frame on which a semiconductor chip is mounted unevenly distributed on the back side in the thickness direction of the package, and at the same time, the lead portion led out of the package has the same It stands up on the surface side in the thickness direction (see FIG. 4B of Patent Document 1). Thereby, especially when this semiconductor package is attached to the heat sink, the position of the lead frame is close to the heat sink, so that the heat can be radiated smoothly and the insulation distance between the lead portion and the heat sink can be earned. .

On the other hand, since the lead frame is unevenly distributed on the back surface side, the lead frame is sandwiched therebetween, and a difference in resin thickness occurs between the package surface side and the back surface side. Similarly, there is a conventional semiconductor device as shown in FIG. 6. However, when the sealing resin is cured, the resin shrinks, and the difference in the resin thickness causes a difference in the amount of shrinkage, causing the package to warp. It becomes. Therefore, when a semiconductor device having a full mold type insulating semiconductor package as shown in FIG. 7 is attached to a heat sink, a gap is generated due to warpage of the back surface of the package, and heat dissipation due to this gap is generated. The decline was a problem.

In view of the above problems, an object of the present invention is to provide a mold for manufacturing a semiconductor device and a manufacturing method thereof, in which the back surface of the package is less likely to warp.

The mold for manufacturing a semiconductor device of the present invention has a cavity formed by combining two of a first mold that forms the front side of the semiconductor device to be manufactured and a second mold that forms the back side. This is a mold for manufacturing a semiconductor device in which a semiconductor chip is formed by holding a lead frame mounted with a semiconductor chip so as to be unevenly distributed from the center in the thickness direction of the cavity to the second mold side and injecting a sealing resin. The distance between the sandwiched lead frame and the surface forming the back surface of the semiconductor device at an arbitrary position of the surface forming the back surface of the semiconductor device to be manufactured on the inner surface of the second mold A raised portion having a height set according to a shrinkage rate when the sealing resin is cured is provided.

The raised portion is formed into a multi-faced shape by drawing a line radially from the arbitrary position toward the outer peripheral portion in the second mold.

A gradient is provided from each vertex of the inner peripheral surface of the second mold toward a middle point of each side to a height lower than the raised portion.

A flat portion is formed at the center of the raised portion, and the radial line is drawn from a predetermined position on the periphery of the flat portion.

The flat part is a polygon, and a predetermined position of the flat part peripheral edge is each vertex of the polygon.

In the method for manufacturing a semiconductor device of the present invention, an arbitrary position of the inner surface of the second mold that forms the back surface side of the semiconductor device is raised, and a radial shape is formed from the arbitrary position toward the outer peripheral portion in the second mold. The step of preparing a resin sealing mold provided with a raised portion having a multi-faced shape by drawing a line, and the first mold and the back surface forming the front side of the semiconductor device to be manufactured The step of holding the lead frame on which the semiconductor chip is mounted so as to be unevenly distributed from the center in the thickness direction of the cavity formed by combining the second mold to be formed to the second mold side, and the molten sealing resin And a step of injecting into the cavity, and the back surface of the body of the semiconductor device to be manufactured has a warping countermeasure shape.

A resin sealing mold is used in which a gradient is provided from each apex of the inner peripheral portion of the second mold toward a middle point of each side to a height lower than the raised portion.

A flat portion is formed at the center of the raised portion, and a resin sealing mold in which the radial line is drawn from a predetermined position on the periphery of the flat portion is used.

The flat portion is polygonal, and a resin sealing mold having a predetermined position on the periphery of the flat portion as a vertex of each of the polygons is used.

A semiconductor device manufactured by the manufacturing method described above.

According to the present invention, between the held lead frame and the surface forming the back surface of the semiconductor device at an arbitrary position of the surface forming the back surface of the manufactured semiconductor device of the mold for manufacturing the semiconductor device. By providing a raised portion having a height that is set according to the distance between them and the shrinkage rate when the sealing resin is cured, a multi-sided concave portion corresponding to the raised portion is formed on the back surface of the package. This recess takes into account molding shrinkage, and a flat back surface can be obtained after shrinkage. Therefore, when this semiconductor device is attached to a heat sink, there is no gap and heat can be radiated efficiently. It becomes possible.

1 is a schematic plan view showing a mold for manufacturing a semiconductor device (second mold) according to an embodiment of the present invention. FIG. 2 is an A-A ′ arrow view (FIG. 2 a) of FIG. 1 and an enlarged view (FIG. 2 b) of a cavity portion. It is a schematic plan view which shows the metal mold | die for semiconductor device manufacture which concerns on the modification of one Embodiment of this invention. It is a perspective view showing a semiconductor device concerning one embodiment of the present invention. It is a back view which shows the semiconductor device which concerns on one Embodiment of this invention. It is a triangular figure which shows an example of the other conventional semiconductor device. It is a schematic sectional drawing which shows the state which attached the semiconductor device of FIG. 6 to the radiation fin.

Hereinafter, a semiconductor device manufacturing mold according to an embodiment of the present invention will be described with reference to FIGS. 1 to 2. As shown in FIGS. 1 and 2, a semiconductor device manufacturing mold 1 according to this embodiment includes an upper mold (first mold) 10, a lower mold (second mold) 20, and these two molds. The semiconductor device 5 is manufactured by placing a lead frame 51 mounted with a semiconductor chip 53 in the cavity 21 and sealing with resin.

The lower mold 20 shown in FIG. 1 has a recess 21b that forms one half of the cavity 21 at the center, and an outer lead alignment portion 22 is formed on one side of the recess 21b. This is because the root of the lead portion 51b rises from one side of the chip mounting portion 51a which is a rectangular plate-like portion of the lead frame 51 main body of the semiconductor device 5 manufactured using the semiconductor device manufacturing die 1. The lead portion 51b is set so that most of the lead portion 51b protrudes from the lower die 20.

Further, a gate 29 is provided on the other side of the recess 21b, and sealing resin is injected from here, and the air that has been in the cavity 21 until then is formed in accordance with each one of the lead portions 51b. The air vent 28 provided around the groove of the outer lead alignment portion 22 is discharged. Note that the positional relationship between the gate 29 and the air vent 28 is not necessarily the same as that in the present embodiment, but it is desirable that they are provided at positions facing each other in order to suitably discharge the air inside the cavity 21.

A raised portion 25 is provided at the center of the recessed portion 21b, and the raised portion 25 has a gentle inclination from the center toward the periphery of the recessed portion 21b. In addition, radial lines 27 are formed that are drawn radially from the center of the raised portion 25 toward the periphery of the concave portion 21b. In combination with the fact that the peripheral ridges 24 are formed at the centers of the four sides of the peripheral edge of the recess 21b and are gently inclined from the four peripheral ridges 24 toward the four corners of the recess 21b, the radial line 27 is The raised portion 25 is made multi-faceted.

The full mold type semiconductor device 5 to be manufactured is often provided with a mounting hole 54 used for mounting on the heat sink so as to penetrate the thickness direction of the semiconductor package 50. The lower mold 20 is provided with a mounting hole forming convex portion 23 for further forming the protrusion. The inclination from the raised portion 25 to the periphery of the concave portion 21b is blocked by the mounting hole forming convex portion 23, but the mounting hole forming convex portion 23 formed in a columnar shape in accordance with the shape of the mounting hole 54, The inclination is formed again from the back side as viewed from the center of the raised portion 25 to the periphery of the recess 21b.

Due to the raised portion 25 provided in the semiconductor device manufacturing mold 1, a depressed portion 55 is temporarily formed in the semiconductor package 50 that is resin-molded by using the semiconductor device manufacturing mold 1. However, in the process of injecting resin into the semiconductor device manufacturing die 1 and thermosetting, the depressed portion 55 actually becomes flat as the resin contracts. This is because the lead frame 51 is unevenly distributed on the back surface side of the semiconductor package 50 that comes into contact with the heat sink during mounting, and the lead frame 51 is sandwiched therebetween, and the amount of resin between the front surface side and the back surface side of the semiconductor package 50 is The great difference is that the action of deforming the semiconductor package 50 is reversed. That is, a larger shrinkage occurs on the front surface side where the amount of resin is large, and the outer peripheral portion of the back surface of the semiconductor package 50 is pulled to the front surface side by this shrinking action, and the back surface becomes flat. As a result, the adhesion to the heat sink can be enhanced.

The reason why the raised portion 25 is provided on the lower mold 20 is that the back surface of the semiconductor package 50 is finally flattened as described above, and therefore the height of the raised portion 25, that is, the depressed portion 55 of the semiconductor package 50. This depth balances with the force with which the outer peripheral portion of the back surface is pulled to the front surface side. That is, the height of the raised portion 25 is defined by the degree of uneven distribution on the back surface side of the lead frame 51 that affects the pulling force on the front surface side and the shrinkage rate when the resin used is cured. .

Further, as described above, the radial line 27 is drawn from the center of the raised portion 25 toward the periphery of the concave portion 21b. However, as shown in FIG. 3, a polygonal flat portion 26 is formed at the center to form a radial shape. A line 27 may be drawn from each vertex of the polygon. When all the radial lines 27 pass through the center point of the raised portion 25, the stress is concentrated at one point. Therefore, there is a problem that the stress is likely to occur when shrinking after resin molding. If 26 is provided, this stress can be dispersed.

The number of polygonal vertices forming the flat portion 26 increases, and the number of radial lines 27 increases, so that the number of surfaces formed on the raised portions 25 also increases. The stress is further distributed.

Next, a method for manufacturing the semiconductor device 5 using the semiconductor device manufacturing mold 1 will be described. In the manufacturing method described here, a semiconductor chip is formed in a cavity 21 formed by combining a step of preparing a semiconductor device manufacturing mold 1 including an upper mold 10 and a lower mold 20 and combining the upper mold 10 and the lower mold 20. 53, a step of holding the lead frame 51 on which the semiconductor chip 53 is mounted, a step of injecting a molten sealing resin into the cavity 21 and thermosetting it, and molding the semiconductor package 50 resin, and releasing from the mold 1 for manufacturing a semiconductor device And post-curing the semiconductor package 50.

In the step of preparing the semiconductor device manufacturing mold 1, as described above, the recess 21 b that forms one half of the cavity 21 is provided at the center, and the groove-shaped outer lead alignment portion 22 and the gate 29 are respectively provided, for example, Prepared together with the upper mold 10 is a lower mold 20 provided with air vents 28 for discharging the air inside the cavity 21 around the groove of the outer lead alignment portion 22 described above. To do.

In this manufacturing method, a raised portion 25 having a gentle slope toward the periphery of the recess 21b is provided at the center of the lower mold 20, and a radial line 27 is drawn radially from the center of the raised portion 25 toward the periphery of the recess 21b. To be processed. Furthermore, a peripheral ridge 24 is formed at the center of each of the four sides of the recess 21b, and the ridge 25 is made to be a multi-faced type in combination with the four peripheral protrusions 24 being gently inclined toward the four corners of the recess 21b. Process to be. Thus, by processing the recess 21b of the lower mold 20 that forms the back surface of the semiconductor package 50, the back surface of the semiconductor package 50 can have a warp countermeasure shape (details will be described later).

When a semiconductor device is manufactured using the semiconductor device manufacturing die 1 processed in this way, first, the chip mounting portion 51a having a rectangular plate shape in plan view, which is the main body of the lead frame 51 punched using a cutting die, The semiconductor chip 53 and the chip mounting portion 51a are electrically connected by bonding the semiconductor chip 53 via solder or the like, and the lead portion 51b and the semiconductor chip 53 are electrically connected using a connector or the like. Prepare things.

The lead frame 51 in this state is aligned with the outer lead alignment portion 22 at the base of the lead portion 51b, and at the same time, a notch portion (not shown) at the tip of the fin portion 51c rising from the other side sandwiching the lead portion 51b and the semiconductor chip 53. ) Is set so as to be fitted to the mounting hole forming convex portion 23. Here, the shape of the lead frame 51 is such that the lead portion 51b located on one side of the rectangular plate-like portion on which the semiconductor chip 53 is mounted and the fin portion 51c located on the other side rise, so that the outer lead When the lead part 51b is set in the alignment part 22, the mounting part of the semiconductor chip 53 is unevenly distributed at a position deep in the recess 21b of the lower mold 20 and very close to the bottom surface.

In the actual manufacturing process, the lead frame 51 generally has a multiple shape of about 10 to 30 pieces by connecting the lead portions 51b with tie bars (not shown). Similarly, the mold 1 for manufacturing a semiconductor device has a multiple shape.

After the lead frame 51 is set, the upper mold 10 is placed thereon, and the molten sealing resin is injected into the cavity 21 formed by combining the lower mold 20 and the upper mold 10. By this step, the lower mold 20 having the recess 21b molds the back surface side of the semiconductor package 50, and the upper mold 10 having the recess 21a molds the front surface side.

Resin is injected from the gate 29. The gate 29 is often formed at the joint of the lower mold 20 and the upper mold 10, and the sealing resin melted by applying heat to the tablet-like epoxy resin or the like is a resin called a runner. It is injected into the semiconductor device manufacturing mold 1 via the passage.

When the resin is injected into the semiconductor device manufacturing die 1, the air that has been in the cavity 21 until then is an air vent provided around the groove of the outer lead alignment portion 22 in which the lead portion 51b is set. 28 is discharged. The positional relationship between the gate 29 and the air vent 28 is not necessarily the same as in the present embodiment. However, depending on the position setting of the gate 29 and the air vent 28 and the shape of the lead frame 51 held inside the cavity 21, a problem may occur in the resin fluidity in the cavity 21, so that voids or the like may be caused by the remaining air. May occur. Considering that the air inside the cavity 21 is preferably discharged, it is desirable to provide the gate 29 and the air vent 28 at positions facing each other.

The injected resin is hardened by one turn by being given a higher temperature. A sealing member called a thermosetting resin such as an epoxy resin becomes an irreversible state after reaching a certain temperature, and its shape is fixed. However, as the temperature of the semiconductor device manufacturing mold 1 decreases, the semiconductor package 50 molded in the cavity 21 starts to shrink. At the time of contraction, the lead frame 51 is unevenly distributed near the bottom surface of the recess 21b of the lower mold 20 as described above, so that the lead frame 51 is placed on the front surface side and the back surface side of the semiconductor package 50 with the lead frame 51 interposed therebetween. A state in which the amount of resin is greatly different between the front surface side and the back surface side of the semiconductor package 50 is created with the 51 interposed therebetween, and this causes a difference in the shrinkage amount between the front surface side and the back surface side.

That is, a larger shrinkage occurs on the surface side with a large amount of resin, and the outer peripheral portion of the back surface of the semiconductor package 50 is pulled to the front surface side by this shrinking action, and the raised portions 25 and the peripheral raised portions 24 provided in the recessed portions 21b The depressed portion 55 formed in accordance with the shape finally becomes a flat state.

When the shrinkage is completed, the semiconductor device 5 is separated from the semiconductor device manufacturing die 1 by using an unillustrated ejector pin, and then the tie bar is cut, so that each semiconductor device 5 is separated into pieces. Further, post-cure (heat aging for stabilizing the material by stress relaxation) is performed. In this post-cure process, the completely shrunk semiconductor package 50 is fixed.

Since the semiconductor device 5 manufactured by this manufacturing method can obtain a flat back surface after shrinkage of the resin, there is no gap when the semiconductor device 5 is attached to a heat sink, and heat is efficiently radiated. It becomes possible to do.

As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the proton of this invention are included.

DESCRIPTION OF SYMBOLS 1 Semiconductor device manufacturing die 5 Semiconductor device 10 Upper mold (first mold)
20 Lower mold (second mold)
21 Cavity 22 Outer lead alignment part 23 Mounting hole forming convex part 24 Periphery raised part 25 Raised part 26 Flat part 27 Radial wire 28 Air vent 29 Gate 50 Semiconductor package 51 Lead frame 51a Chip mounting part 51b Lead part 51c Fin part 54 Attachment Hole 55 depression

Claims (10)

A lead frame mounted with a semiconductor chip is placed inside the cavity formed by combining the first mold that forms the front side of the semiconductor device to be manufactured and the second mold that forms the back side. A mold for manufacturing a semiconductor device, which is held so as to be unevenly distributed from the center in the thickness direction to the second mold side, and a semiconductor package is formed by injecting a sealing resin,
The distance between the sandwiched lead frame and the surface forming the back surface of the semiconductor device at an arbitrary position of the surface forming the back surface of the manufactured semiconductor device on the inner surface of the second mold, and A mold for manufacturing a semiconductor device, comprising a raised portion having a height set in accordance with a shrinkage rate when the sealing resin is cured. 2. The gold for manufacturing a semiconductor device according to claim 1, wherein the raised portion is formed into a multifaceted shape by drawing a line radially from the arbitrary position toward an outer peripheral portion in the second mold. Type. 3. The semiconductor according to claim 1, wherein a gradient is provided from each vertex of the inner peripheral portion of the second mold toward a middle point of each side to a height lower than the raised portion. Mold for device manufacturing. 4. The semiconductor device manufacturing according to claim 2, wherein a flat portion is formed at the center of the raised portion, and the radial line is drawn from a predetermined position on the periphery of the flat portion. 5. Mold. 5. The mold for manufacturing a semiconductor device according to claim 4, wherein the flat part is a polygon, and a predetermined position of the periphery of the flat part is a vertex of each of the polygons. By raising an arbitrary position of the inner surface of the second mold that forms the back surface side of the semiconductor device and drawing a line radially from the arbitrary position toward the outer peripheral portion in the second mold, Formed by combining a process for preparing a mold for resin sealing provided with a raised portion having a shape, and a first mold for forming the front side of the semiconductor device to be manufactured and a second mold for forming the back side Holding the lead frame on which the semiconductor chip is mounted so as to be unevenly distributed from the center in the thickness direction to the second mold side, and injecting molten sealing resin into the cavity A method for manufacturing a semiconductor device. A resin sealing mold is used in which a gradient is provided from each apex of the inner peripheral portion of the second mold toward a middle point of each side to a height lower than the raised portion. Item 7. A method for manufacturing a semiconductor device according to Item 6. 7. A resin sealing mold in which a flat portion is formed at the center of the raised portion and the radial line is drawn from a predetermined position on the periphery of the flat portion is used. Or a method of manufacturing a semiconductor device according to 7; 9. The semiconductor device according to claim 8, wherein the flat portion is a polygon, and a resin sealing mold is used in which a predetermined position of the periphery of the flat portion is a vertex of each of the polygons. Production method. A semiconductor device manufactured by the manufacturing method according to claim 6.

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