Method of fabricating a semiconductor device having a heat sink with an exposed surface

A method includes: mounting a plurality of semiconductor elements on a substrate having wirings; connecting electrically electrodes of the semiconductor elements and the wirings; sealing the semiconductor elements with a resin, which is carried out by bringing a thermal conductor having a concavity and the substrate to be in contact with each other so that the semiconductor elements are positioned within the concavity and by filling the concavity with the resin; and separating respective semiconductor elements 1. In the resin-sealing step, in a state where the thermal conductor is arranged with its concavity facing up and the concavity of the thermal conductor is filled with a liquid resin, the semiconductor elements are dipped in the liquid resin in the concavity and the liquid resin is solidified. Due to these steps, a semiconductor device can be manufactured without experiencing troubles such as short circuit of the metal thin wires or imperfect filling of resin during the manufacturing steps, and thus semiconductor devices with stable quality can be manufactured.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device suitably used for a case in which semiconductor elements that generate much heat power are mounted, and a method for manufacturing the semiconductor device.

2. Description of Related Art

With the recent trend toward multifunction and reduction in size and thickness of electronic equipment, the semiconductor devices have become smaller and thinner, and the number of terminals tends to increase. For coping with this tendency, a so-called BGA (Ball Grid Array) package has been used. Unlike a conventional QFP (Quad Flat Package), a BGA package does not have an external lead protruding in the lateral direction. Instead, the BGA package has solder balls that are arranged in a matrix on the lower surface of a substrate and that serve as external electrodes for an electric connection with a mother board.

Since it is expected that semiconductor elements generating much heat are mounted on such a BGA package, heat diffusion is taken into consideration in the designing (see JP H08-139223 A for example).

FIG. 17is a cross-sectional view showing a configuration of a conventional semiconductor device101.FIG. 18is a perspective view showing a thermal conductor119of the semiconductor device101inFIG. 17. Wiring patterns112are formed on the both surfaces of a substrate113made of an insulating resin, and the wiring patterns112are connected electrically to each other through via holes117. A semiconductor element111is mounted on one principal surface of the substrate113through an adhesive114and connected electrically to the wiring pattern112on the substrate113through metal thin wires115.

The thermal conductor119is made of a material having a preferable thermal conductivity such as Cu, Cu alloy, Al, Al alloy and Fe—Ni alloy, and it covers the surface of the substrate113on which the semiconductor element is mounted (semiconductor-element-mounting surface). The thermal conductor119has a contact portion122that is in contact with the substrate113, an inclined portion121formed with an inclination from the contact portion122, and a flat portion120formed continuously from the inclined portion121and to be parallel to the substrate113. As shown inFIG. 18, a plurality of openings131are formed on the contact portion122and on the inclined portion121. InFIG. 17, a sealing resin116is filled in the spacing between the thermal conductor119and the substrate113so as to seal the semiconductor-element-mounting surface of the substrate113, the semiconductor element111, the adhesive114, and the metal thin wires115integrally. Ball electrodes118are arranged in a matrix on one of the wiring patterns112of the substrate113opposite to the semiconductor-element-mounting surface.

The semiconductor device101is configured so that heat generated by the semiconductor element111is diffused through the via holes117and the ball electrodes118, and furthermore, the heat is diffused also from the semiconductor-element-mounting surface of the substrate113through the thermal conductor119, and thus the semiconductor device101has excellent heat diffusion.

Furthermore, by providing a heat sink or the like (not shown) on an upper surface of the thermal conductor119, namely, a part at which the sealing resin116is not formed, the effect of heat diffusion from the semiconductor-element-mounting surface can be enhanced further.

Next, a method for manufacturing the conventional semiconductor device101will be described below.FIGS. 19A-19Fare cross-sectional views showing a process of manufacturing the semiconductor device101. First, as shown inFIG. 19A, a substrate113with wiring patterns112formed on both surfaces thereof is prepared, and the adhesive114is applied on predetermined positions of the semiconductor-element-mounting surface of the substrate113. Next, as shown inFIG. 19B, the semiconductor element111is placed on the adhesive114and adhered securely. Next, as shown inFIG. 19C, an electrode (not shown) of the semiconductor element111mounted on the substrate113and the wiring pattern112formed on the upper surface of the substrate113are connected electrically to each other through the metal thin wires115. Next, as shown inFIG. 19D, the thermal conductor119is brought into contact with the substrate113so as to cover the semiconductor element111.

Next, as shown inFIG. 19E, the substrate113in contact with the thermal conductor119is set on a lower mold133of a sealing mold134, and sealed securely with an upper mold132of the sealing mold134. At this time, the lower surface of the upper mold132of the sealing mold134and the upper surface of the thermal conductor119are in contact with each other. In this state, a sealing resin116is injected in an injection direction136from an injection gate135formed horizontally in the upper mold132of the sealing mold134. As a result, through the openings131of the thermal conductor119as shown inFIG. 18, the sealing resin116enters the space between the thermal conductor119and the substrate113. At that time, in the vicinity of the injection gate135, the sealing resin116is on the upper surface of the thermal conductor119. After curing the sealing resin116, the upper mold132and the lower mold133of the sealing mold134are disengaged. Finally, as shown inFIG. 19F, the ball electrodes118are formed by attaching solder balls to external pad electrodes of the wiring pattern112formed on a surface of the substrate113opposite to the semiconductor-element-mounting surface, thereby configuring external terminals. In this manner, the semiconductor device101can be manufactured.

The conventional semiconductor device101can diffuse heat since the upper surface of the thermal conductor119is exposed from the sealing resin116. However, since in the resin-sealing step, the resin is injected from the injection gate135provided at the sealing mold134(hereinafter, this method is referred to as a side gate method), the metal thin wires115will be deformed easily due to the resin injection.

Here, the deformation of the metal thin wires during the resin-sealing step in the side gate method will be described in detail with reference toFIGS. 20A-20C.FIGS. 20A-20Cshow a typical BGA, from which a thermal conductor is omitted for clearly showing the phenomenon.

FIG. 20Ais a cross-sectional view showing a state just before a resin-sealing in the side gate method, and that corresponds to the cross-section taken along the line J-J′ inFIG. 20BandFIG. 20C.FIG. 20Bis a top view showing the appearance of the metal thin wires115before resin injection, andFIG. 20Cis a top view showing the appearance of the metal thin wires115and a flowing pattern of the resin after the resin injection.

As shown inFIG. 20C, the resin injected from the injection gate135in a direction136moves forwards while forming ripples centering on the injection gate135. Here, each of dotted lines137indicates a position the resin reaches at a point of time.

The deformation level of the metal thin wires115has a relationship to “resin viscosity”, “resin current speed”, “angle of the tip of the flowing resin with respect to the metal thin wires” and the like. As shown inFIG. 20B, the metal thin wires115are arranged radially from the center of the semiconductor element111. Therefore, as shown inFIG. 20C, after the resin injection is finished, some of the metal thin wires that are located in the vicinity of the injection gate135or at the side diagonally opposite to the injection gate135and thus not angled substantially with respect to the flowing direction of the resin are not deformed substantially. However, the remaining metal thin wires115are deformed depending on “resin current speed”, “angle of the tip of the flowing resin with respect to the metal thin wires”, and the like.

As a result, in a case of resin-sealing of the conventional side gate method carried out for a semiconductor device with metal thin wires115arranged across at a high density in accordance with the demand for smaller device and increase in the number of terminals, problems such as a short circuit may be caused by deformation of the metal thin wires115when the adjacent metal thin wires115are arranged at a narrow pitch.

Moreover, when the thermal conductor119as shown inFIG. 18is included, the flow of the sealing resin is complicated and the fluidity deteriorates. This may cause a problem of imperfect filling of the sealing resin as well as the problem of deformation of the metal thin wires.

SUMMARY OF THE INVENTION

Therefore, with the foregoing in mind, it is an object of the present invention to provide a semiconductor device with stable quality, which can be manufactured without problems such as a short circuit in the metal thin wires or imperfect resin filling during a manufacturing process. Another object of the present invention is to provide a method for manufacturing the semiconductor device.

A first method of the present invention for manufacturing a semiconductor device includes: mounting a plurality of semiconductor elements on a substrate having wirings; connecting electrodes of the semiconductor elements and the wirings electrically; sealing the semiconductor elements with a resin, which is carried out by bringing a thermal conductor having a concavity and the substrate to be in contact with each other so that the semiconductor elements are positioned within the concavity and by filling the concavity with the resin; and separating the respective semiconductor elements. For solving the above-described problems, the method is characterized in that, in the resin-sealing step, in a state where the thermal conductor is arranged with its concavity facing up and the concavity of the thermal conductor is filled with a liquid resin, the semiconductor elements are dipped in the liquid resin in the concavity and subsequently the liquid resin is solidified.

A second method of the present invention for manufacturing a semiconductor device includes: mounting a plurality of semiconductor elements on a lead frame; connecting electrodes of the semiconductor elements and the lead frame electrically; sealing the semiconductor elements with a resin, which is carried out by bringing a thermal conductor having a concavity and the lead frame to be in contact with each other so that the semiconductor elements are positioned within the concavity and by filling the concavity with the resin; and separating the respective semiconductor elements. For solving the above-described problem, the method is characterized in that, in the resin-sealing step, in a state where the thermal conductor is arranged with its concavity facing up and the concavity of the thermal conductor is filled with the resin, the semiconductor elements are dipped in the liquid resin in the concavity and the liquid resin is solidified.

A first semiconductor device of the present invention includes a semiconductor element, a substrate on which the semiconductor element is mounted, a thermal conductor, and a sealing resin that is provided into the spacing between the substrate and the thermal conductor so as to seal the semiconductor element. For solving the above-described problem, the thermal conductor is bonded to the surface of the sealing resin so as to cover the sealing resin.

A second semiconductor device of the present invention includes a semiconductor element, a lead frame on which the semiconductor element is mounted, a thermal conductor, and a sealing resin that is provided into the spacing between the lead frame and the thermal conductor so as to seal the semiconductor element. For solving the above-described problem, the thermal conductor is bonded to the surface of the sealing resin so as to cover the sealing resin.

DETAILED DESCRIPTION OF THE INVENTION

A first method of the present invention for manufacturing a semiconductor device is characterized in that, in a resin-sealing step, in a state where a thermal conductor is arranged with its concavity facing up and the concavity of the thermal conductor is filled with a liquid resin, a plurality of semiconductor elements arranged on a substrate are dipped in the liquid resin in the concavity and the liquid resin is solidified. According to this manufacturing method, since the metal thin wires of the semiconductor device will not be shorted during the manufacturing process, and furthermore, since a problem of imperfect filling of resin will not occur, semiconductor devices with stable quality can be manufactured.

A second method of the present invention for manufacturing a semiconductor device is characterized in that, in a resin-sealing step, in a state where a thermal conductor is arranged with its concavity facing up and the concavity of the thermal conductor is filled with a liquid resin, a plurality of semiconductor elements arranged on a lead frame are dipped in the liquid resin in the concavity and the liquid resin is solidified. According to this manufacturing method, since the metal thin wires of the semiconductor device will not be shorted during the manufacturing process, and furthermore, since a problem of imperfect filling of resin will not occur, semiconductor devices with stable quality can be manufactured.

A first semiconductor device of the present invention includes a semiconductor element, a substrate on which the semiconductor element is mounted, a thermal conductor, and a sealing resin that is provided to the spacing between the substrate and the thermal conductor so as to seal the semiconductor element. The thermal conductor is bonded to the surface of the sealing resin so as to cover the sealing resin.

A second semiconductor device of the present invention includes a semiconductor element, a lead frame on which the semiconductor element is mounted, a thermal conductor, and a sealing resin that is provided to the spacing between the lead frame and the thermal conductor so as to seal the semiconductor element. The thermal conductor is bonded to the surface of the sealing resin so as to cover the sealing resin.

Based on the above-described configurations, the semiconductor device and the method for manufacturing the semiconductor device of the present invention can be varied as described below.

Namely, in the first method for manufacturing a semiconductor device, the state where the concavity of the thermal conductor is filled with a liquid resin can be obtained by injecting the liquid resin into the concavity of the thermal conductor.

Alternatively, the state where the concavity of the thermal conductor is filled with a liquid resin can be obtained by casting a solid resin into the concavity of the thermal conductor and by heating the thermal conductor so as to melt the solid resin.

The thermal conductor before the separation step can be provided as a group of joined thermal conductors, and the separation step can be carried out by cutting the substrate and the thermal conductor group simultaneously.

The thermal conductor before the separation step can be provided as a group of joined thermal conductors, and the separation step can be carried out by cutting the substrate, the thermal conductor group and the sealing resin simultaneously.

In the second method for manufacturing a semiconductor device, the state where the concavity of the thermal conductor is filled with a liquid resin can be obtained by injecting the liquid resin into the concavity of the thermal conductor.

Alternatively, the state where the concavity of the thermal conductor is filled with a liquid resin can be obtained by casting a solid resin into the concavity of the thermal conductor and by heating the thermal conductor so as to melt the solid resin.

The thermal conductor before the separation step can be provided as a group of joined thermal conductors, and the separation step can be carried out by cutting the lead frame and the thermal conductor group simultaneously.

The thermal conductor before the separation step can be provided as a group of joined thermal conductors, and the separation step can be carried out by cutting the lead frame, the thermal conductor group and the solidified resin simultaneously.

In the first and second methods of manufacturing a semiconductor device, the resin-sealing step can be carried out by sealing a plurality of semiconductor elements simultaneously.

The thermal conductor group can include the thermal conductors formed in a strip. Alternatively, the thermal conductor group can include the thermal conductors formed in a matrix. It is also possible that slits are formed at the joints between the thermal conductors of the thermal conductor group.

In the first semiconductor device, the thermal conductor can be configured to cover the entire surface of the sealing resin. Alternatively, it is possible that the sealing resin is exposed from the surface composed of the side face of the substrate and also the side face of the thermal conductor.

It is also possible that the sealing resin is exposed from two side-faces opposed to each other. Alternatively, the sealing resin can be exposed from all of the side faces.

The electrode of the semiconductor element and the wirings of the substrate can be connected electrically to each other by the metal thin wires. Alternatively, the electrode of the semiconductor element and the wirings of the substrate can be connected electrically via bumps.

The surface of the semiconductor element opposite to the surface on which a circuit is formed can be configured to be in contact with the thermal conductor.

In the second semiconductor device, the thermal conductor can be configured to cover the entire surface of the sealing resin. Alternatively, the sealing resin can be exposed from the surface composed of the side face of the lead frame and the side face of the thermal conductor.

It is also possible that the sealing resin is exposed from two side-faces opposed to each other. Alternatively, the sealing resin can be exposed from all of the side faces.

Alternatively, the thermal conductor can be adhered to the lead frame through an insulating adhesive member.

A configuration of a semiconductor device according to Embodiment 1 of the present invention will be described below.FIG. 1includes views for showing the configuration of a semiconductor device1ain Embodiment 1 of the present invention.FIG. 1Ais a top view of the semiconductor device1a, andFIG. 1Bis a cross-sectional view taken along the line A-A inFIG. 1A.

As shown inFIG. 1B, wiring patterns12are formed on both surfaces of a substrate13made of an insulating resin. The wiring patterns12are connected electrically to each other through via holes17. A semiconductor element11ais adhered to the substrate13through an adhesive14. An electrode is formed on the upper surface of the semiconductor element11aand connected to the wiring pattern12through metal thin wires15. A sealing resin16seals integrally the semiconductor-element-mounting surface of the substrate13, the semiconductor element11a, the adhesive14and the metal thin wires15.

A thermal conductor19is made of a material having preferable thermal conductivity, such as Cu, Cu alloy, Al, Al alloy, and Fe—Ni alloy. The thermal conductor19is shaped like a hat, and it has a contact portion19a, an inclined portion19bformed with an inclination from the contact portion19a, and a flat portion19cformed continuously from the inclined portion19band in parallel to the contact portion19a. That is, the thermal conductor19has a concavity defined by the inclined portion19band the flat portion19c. The contact portion19ais in contact with the substrate13, and the concavity is bonded to the sealing resin16to cover the sealing resin16. The thermal conductor19can be in contact with the substrate13and further adhered securely to the substrate13with an adhesive (not shown) or the like. The openings131as shown inFIG. 18are not formed in the thermal conductor19.

The flat portion19cof the thermal conductor19is exposed entirely or partially from the sealing resin16to the exterior. Ball electrodes18are arranged in a matrix on a surface (ball-formation surface) of the substrate13opposite to the semiconductor-element-mounting surface, and connected electrically to the wiring pattern12of the substrate13.

In the configuration of the semiconductor device1a, the heat generated by the semiconductor element11ais diffused through the via holes17and the ball electrodes18, and furthermore the heat is diffused also from the semiconductor-element-mounting surface of the substrate13through the thermal conductor19. Therefore, the semiconductor device1ahas excellent heat diffusion. Since the exterior of the thermal conductor is not provided with a sealing resin, the heat diffusion efficiency is improved further. Furthermore, by providing a heat sink or the like (not shown) on the part at which the thermal conductor19is exposed from the sealing resin16, the effect of heat diffusion of the substrate13from the semiconductor-element-mounting surface can be improved further.

Unlike a conventional configuration, in the semiconductor device according to this embodiment, there is no necessity of forming openings in the thermal conductor for the purpose of injecting a sealing resin, and thus the effect of suppressing electromagnetic noise received or emitted by the semiconductor device will be improved.

Next, a method for manufacturing the semiconductor device la according to the present embodiment will be described below.FIGS. 2A-2Fare cross-sectional views showing a process for manufacturing the semiconductor device1a.

First, as shown inFIG. 2A, a substrate13having wiring patterns12formed on both the surfaces is prepared, and an adhesive14is applied on the predetermined positions of semiconductor-element-mounting surface of the substrate13. Next, as shown inFIG. 2B, semiconductor elements ha are arranged on the adhesive14applied on the predetermined positions of the substrate13and adhered securely. Next, as shown inFIG. 2C, electrodes (not shown) of the semiconductor elements11amounted on the substrate13are connected electrically to electrodes of the wiring patterns12formed on the semiconductor-element-mounting surface of the substrate13through the metal thin wires15. The processes by this step are common to those in the method for manufacturing the conventional semiconductor device101as shown inFIGS. 19A-19C.

Next, a thermal conductor group41as shown inFIG. 2Dis prepared by integrally forming a plurality of thermal conductors19. The thermal conductor group41is formed by etching or pressing a metal plate made of a material having a preferable thermal conductivity, such as Cu, Cu alloy, Al, Al alloy and Fe—Ni alloy so as to form concavities integrally. The shape of the thermal conductor19is not limited to the quadrangle as shown in the present embodiment, but it may be round or polygonal.

FIG. 3is a top view showing the thermal conductor group41aformed by aligning and integrating a plurality of thermal conductors19. The thermal conductor group41aincludes the thermal conductors19formed in a line in accordance with the pitch for mounting the semiconductor elements with respect to the substrate on which the semiconductor elements will be mounted. The cutoff line43indicates a line along which the thermal conductor group41is cut and separated to form a plurality of thermal conductors19.

FIG. 4is a top view showing a thermal conductor group41bformed by integrating a plurality of thermal conductors19arranged in a matrix. The thermal conductor group41bincludes the thermal conductors19formed in a matrix in accordance with the pitch for mounting the semiconductor elements with respect to the substrate13on which the semiconductor elements11awill be mounted. It is possible to seal a plurality of semiconductor elements11asimultaneously by using the thermal conductor group41aor41b.

FIG. 5is an enlarged top view of a part of the thermal conductor group41a. In the thermal conductor group41a, slits44are formed along the cutoff line43for easy cutting.

Next, as shown inFIG. 2D, the sealing resin16is injected into the concavity of the thermal conductor group41in a state where the thermal conductor group41is set so that the surface facing the semiconductor elements11ais turned upward (i.e., the concavity is faced up). At this time, for the sealing resin16, a liquid resin is injected. Alternatively, a solid resin is cast and heated to be melted in the concavity of the thermal conductor group41. Here, the semiconductor-element-mounting surface of the substrate13is turned downward, and the contact portion19aof the thermal conductor19is brought into contact with the substrate13while dipping the semiconductor element11ain a liquid sealing resin16, and thus a resin-sealing is carried out.

In this process where the thermal conductor group41is employed in place of the mold134used in the sealing step in the method for manufacturing a conventional semiconductor device as shown inFIG. 19D, the steps shown inFIGS. 19D and 19Eare combined into the step as shown inFIG. 2D, thereby decreasing the number of steps. Moreover, a resin-sealing can be carried out without using an expensive mold. In addition, unlike the resin-sealing step included in the side gate method, a resin will flow less. And thus problems such as deformation of the metal thin wires15can be suppressed.

Next, as shown inFIG. 2E, the ball electrodes18are formed in a matrix in accordance with the wiring pattern12formed on the ball-formation surface of the substrate13. Finally, as shown inFIG. 2F, the components are separated by cutting with a rotary blade42for each of the semiconductor elements11a. In this manner, the semiconductor device1aas shown inFIG. 1can be manufactured. When the thermal conductor group41and the substrate13are cut with the rotary blade42, metal chips of the thermal conductor group41are generated. However, since the slits44are formed in the thermal conductor group41along the cutoff line43, the amount of the metal chips can be decreased. As a result, adhesion of the metal chips to the semiconductor device1ais reduced.

FIG. 6Ais a top view showing a semiconductor device1bas a variation of the semiconductor device1a.FIG. 6Bis a cross-sectional view taken along the line B-B′ inFIG. 6A. The contact portion20adoes not reach the rim of the substrate13, and it is not connected to a thermal conductor adjacent to the thermal conductor20in the manufacturing process. By using this thermal conductor20, metal chips can be reduced at the time of separating the semiconductor devices, and thus adhesion of the metal chips to the semiconductor device can be reduced.

A semiconductor device according to Embodiment 2 of the present invention will be described below.FIG. 7Ais a top view showing the configuration of a semiconductor device2ain the present embodiment.FIG. 7Bis a cross-sectional view taken along the line C-C′ inFIG. 7A.FIG. 7Cis a cross-sectional view taken along the line D-D′ that is perpendicular to the line C-C′ inFIG. 7A. In the following description of embodiment, the same reference numerals may be assigned to the same components as those of the semiconductor device1ain Embodiment 1 in order to avoid the duplication of explanations.

The thermal conductor21shown inFIG. 7Bis made of a material having a preferable thermal conductivity, such as Cu, Cu alloy, Al, Al alloy and Fe—Ni alloy. The thermal conductor21includes a contact portion21a, an inclined portion21bformed with an inclination from the contact portion21a, and a flat portion21cformed continuously from the inclined portion21band in parallel to the contact portion21a. The inclined portion21band the flat portion21cdefine a concavity. The contact portion21ais in contact with the substrate13, and the concavity is bonded to the surface of the sealing resin16so as to cover the sealing resin16. The thermal conductor21covers not the entire surface of the sealing resin16, but as shown inFIG. 7C, the sealing resin16is exposed along the cross section of the separated semiconductor device at the both ends of the line D-D′ of the semiconductor device2a. The thermal conductor21can be in contact with the substrate13and furthermore adhered securely to the substrate13with an adhesive (not shown) or the like. The flat portion21cof the thermal conductor21is exposed to the outside entirely or partially from the sealing resin16. In this configuration, since the sealing resin is not provided outside the thermal conductor21, the heat diffusion efficiency is improved.

Next, a method for manufacturing the semiconductor device2ain the present embodiment will be described.FIGS. 8A-8Fare cross-sectional views showing the process of manufacturing the semiconductor device2a. First, as shown inFIG. 8A, a substrate13with wiring patterns12formed on both the surfaces is prepared, and an adhesive14is applied on the predetermined positions of the semiconductor-element-mounting surface of the substrate13. Next, as shown inFIG. 8B, the semiconductor elements11aare arranged on the adhesive14applied on the predetermined positions of the substrate13, and adhered securely. Next, as shown inFIG. 8C, electrodes of the semiconductor elements11amounted on the substrate13are connected electrically to the wiring pattern12formed on the semiconductor-element-mounting surface of the substrate13through the metal thin wires15. The process up to this step is common to the process in the method for manufacturing the conventional semiconductor device101as shown inFIGS. 19A-19C.

Next, a thermal conductor group45as shown inFIG. 8Dis prepared by integrally forming a plurality of thermal conductors21. The thermal conductor group45is formed by etching or pressing a metal plate made of a material having a preferable thermal conductivity, such as Cu, Cu alloy, Al, Al alloy and Fe—Ni alloy so as to form a concavity integrally. The concavity of the thermal conductor21is shaped to cover the plural semiconductor elements11a.

Next, as shown inFIG. 8D, the sealing resin16is injected into the concavity of the thermal conductor group45in a state where the thermal conductor group45is placed so that the surface facing the semiconductor elements11ais turned upward. At this time, for the sealing resin16, a liquid resin is injected. Alternatively, a solid resin is cast and heated to be melted in the concavity of the thermal conductor group45. Here, the semiconductor-element-mounting surface of the substrate13is turned downward, and the substrate13and the contact portion21aare brought into contact with each other while dipping the semiconductor elements11ain the liquid resin16, and thus a resin-sealing is carried out.

Since the thermal conductor group45is employed in place of the mold134used in the sealing step in the method for manufacturing a conventional semiconductor device as shown inFIG. 19D, the steps shown inFIGS. 19D and 19Eare combined into the step as shown inFIG. 8D, thereby decreasing the number of steps. In addition, the resin-sealing step can be carried out without using an expensive mold. Furthermore, unlike the case of resin-sealing in a side gate method, a resin will flow less, and thus problems such as deformation of the metal thin wires15can be suppressed.

Next, as shown inFIG. 8E, the ball electrodes18are formed in a matrix in accordance with the wiring pattern12formed on the ball-formation surface of the substrate13. Finally, as shown inFIG. 8F, the components are cut and separated with a rotary blade42for each of the semiconductor elements11a, and thus the semiconductor device2aas shown inFIG. 7can be manufactured.

The above-described separation step in the manufacturing method relates to a case of using a substrate13on which the semiconductor elements11aare arranged in a strip. In this case, as shown inFIG. 7, the semiconductor device2ais configured so that the sealing resin is exposed from two of the side faces opposed to each other among the cross sections of the separated semiconductor devices2a.

FIG. 9Ais a top view showing a semiconductor device2bas a variation of the semiconductor device2a.FIG. 9Bis a cross-sectional view taken along the line E-E′ inFIG. 9A. The thermal conductor22consists of only a flat portion, and the sealing resin16is exposed from all of the side faces. Even with this configuration, effects comparative to those of the semiconductor device2bcan be obtained.

The process for manufacturing the semiconductor device2bis substantially same as the process for manufacturing the semiconductor device2aexcept for the use of a thermal conductor group formed such that the flat portion is shaped to cover semiconductor chips arranged in a matrix, in the step as shown inFIG. 8D.

A semiconductor device according to Embodiment 3 of the present invention will be described below.FIG. 10Ais a top view showing a configuration of a semiconductor device3in Embodiment 3 of the present invention.FIG. 10Bis a cross-sectional view taken along the line F-F′ inFIG. 10A. In the following description of embodiment, the same reference numerals may be assigned to the same components as those of the semiconductor device1ain Embodiment 1 in order to avoid the duplication of explanations.

A semiconductor element11chas an electrode formed on the lower surface (circuit-formation surface). Bumps24connect the electrode (not shown) on the semiconductor element11cand a wiring pattern12on the semiconductor-element-mounting surface of the substrate13. The spacing between the semiconductor element11cand the substrate13is filled with a resin25, except for the region where the bumps24are formed.

A thermal conductor23is made of a material having preferable thermal conductivity, such as Cu, Cu alloy, Al, Al alloy and Fe—Ni alloy. The thermal conductor23includes a contact portion23a, an inclined portion23bformed with an inclination from the contact portion23a, and a flat portion23cformed continuously from the inclined portion23band in parallel to the contact portion23a. The inclined portion23band the flat portion23cdefine a concavity. The contact portion23ais in contact with the substrate13, and the concavity is bonded to the surface of the sealing resin16so as to cover the sealing resin16.

The flat portion23cis in contact with the upper surface of the semiconductor element11c. The contact portion23amay be in contact with the substrate13and further adhered securely to the substrate13with an adhesive (not shown) or the like. The flat portion23cof the thermal conductor23is exposed entirely or partially to outside from the sealing resin16.

As mentioned above, in the configuration where the flat portion23cof the thermal conductor23and the upper surface of the semiconductor element11care in contact with each other, the heat generated at the semiconductor element11cis conducted efficiently to the thermal conductor23, and thus the heat diffusion efficiency at the semiconductor element11cis improved. Moreover, since the sealing resin is not provided outside the thermal conductor23, the heat diffusion efficiency is improved further. The heat diffusion efficiency at the semiconductor element11ccan be improved even further by providing a heat sink or the like at the flat portion23c.

Unlike the conventional semiconductor device, the semiconductor device according to the present embodiment does not need holes formed in the thermal conductor in order to inject a sealing resin, and thus the effect of suppressing electromagnetic noise that is received or emitted by the semiconductor device.

Next, a method for manufacturing the semiconductor device3in the present embodiment will be described with reference to the attached drawings.FIGS. 11A-11Fare cross-sectional views showing the process for manufacturing the semiconductor device3. First, as shown inFIG. 11A, the bumps24are formed on the electrodes of the semiconductor element11c. Next, as shown inFIG. 11B, a substrate13having wiring patterns12formed on both the surfaces is prepared, and the semiconductor elements11care arranged on the predetermined positions of the semiconductor-element-mounting surface of the substrate13by pressing the bumps24on the wiring pattern12of the substrate13. Next, as shown inFIG. 11C, a liquid resin25is injected into the space between the semiconductor elements11cand the substrate13by using the capillary phenomenon.

Next, a thermal conductor group46consisting of a plurality of thermal conductors23integrally formed is prepared. The thermal conductor group46is formed by etching or pressing a metal plate made of a material having preferable thermal conductivity, such as Cu, Cu alloy, Al, Al alloy and Fe—Ni alloy in order to shape concavities integrally. The shape of the thermal conductor23is not limited to the quadrangle as shown in the present embodiment, but it can be round or polygonal. The thermal conductor group46is formed in accordance with the semiconductor elements arranged on the substrate13, and it can include the thermal conductors23formed in a strip as shown inFIG. 3or formed in a matrix as shown inFIG. 4.

Next, as shown inFIG. 11D, in a state where the thermal conductor group46is set so that the surface facing the semiconductor elements11cis turned upward, the sealing resin16is injected into the concavities of the thermal conductor group46. At this time, for the sealing resin16, a liquid resin is injected. Alternatively, a solid resin is cast and heated to be melted in the concavities of the thermal conductor group46. Next, the surface of the substrate13on which the semiconductor elements11care mounted is turned downward, and the substrate13is brought into contact with the contact portion23aof the thermal conductor23while dipping the semiconductor elements11cin the liquid sealing resin16, and thus a resin-sealing is carried out. In a case of casting a solid resin, the solid resin can be one block or more than one blocks, or a powder.

In this step, the thermal conductor group46is employed in place of the mold134used in the sealing step in the method for manufacturing a conventional semiconductor device as shown inFIG. 19D, thereby the steps shown inFIGS. 19D and 19Eare combined into the step as shown inFIG. 11D, and thus the number of steps is decreased. Moreover, a resin-sealing can be carried out without using an expensive mold.

Next, as shown inFIG. 11E, the ball electrodes18are formed in a matrix in accordance with the wiring pattern12on the ball-formation surface of the substrate13. Finally, as shown inFIG. 11F, the components are cut and separated with a rotary blade42for each of the semiconductor elements11a, and thus the semiconductor device3as shown inFIG. 10is manufactured.

The semiconductor device3in the present embodiment has an internal structure as a flip-chip package where the electrodes of the semiconductor elements11cand the electrodes of the wiring patterns12are connected to each other via bumps. However, the present invention is not limited to this embodiment. The semiconductor device can be configured by using the thermal conductor21similar to that of Embodiment 2 so that the sealing resin is exposed from the end faces of the package.

A semiconductor device according to Embodiment 4 of the present invention will be described below.FIG. 12Ais a top view showing a configuration of a semiconductor device4ain Embodiment 4 of the present invention.FIG. 12Bis a cross-sectional view taken along the line G-G′ inFIG. 12A. In the following description of embodiment, the same reference numerals may be assigned to the same components as those of the semiconductor device1ain Embodiment 1 in order to avoid the duplication of explanations.

A lead frame27for inputting/outputting from/to the exterior includes a die pad portion28and a lead portion29. On the die pad portion28, a semiconductor element11ais arranged through an adhesive14. The lead portion29is connected to an electrode on the upper surface of the semiconductor element11athrough a metal thin wire15.

The thermal conductor26is made of a material having a preferable thermal conductivity, such as Cu, Cu alloy, Al, Al alloy and Fe—Ni alloy, and arranged to cover the sealing resin16. The thermal conductor26includes a flat portion26cand an inclined portion26bformed with an inclination from the flat portion26c. The inclined portion26band the flat portion26cdefine a concavity. The concavity of the thermal conductor26is adhered to the surface of the sealing resin16so as to cover the sealing resin16. The thermal conductor26is adhered to the lead frame27through the sealing resin16. The flat portion26cof the thermal conductor26is exposed entirely or partially to the exterior from the sealing resin16. In this configuration, since the sealing resin is not provided outside the thermal conductor26, the heat diffusion efficiency is improved.

Unlike the conventional semiconductor device, the semiconductor device according to the present embodiment does not need holes formed in the thermal conductor in order to inject a sealing resin, and thus the effect of suppressing electromagnetic noise that is received or emitted by the semiconductor device will be improved.

Next, a method for manufacturing the semiconductor device4ain the present embodiment will be described below.FIGS. 13A-13Fare cross-sectional views showing the process for manufacturing the semiconductor device4a.

First, as shown inFIG. 13A, a tape30is stuck to a lead frame27including a die pad portion28on which semiconductor elements are mounted and a lead portion29, on the surface opposite to the semiconductor-element-mounting surface. Next, an adhesive14is applied on the semiconductor-element-mounting surface of the die pad portion28. Next, as shown inFIG. 13B, the semiconductor element11ais arranged and adhered securely on the adhesive14applied on the die pad portion28. Next, as shown inFIG. 13C, electrodes on the upper surface of the semiconductor element11amounted on the adhesive14and the lead portion29are connected electrically to each other through the metal thin wires15.

Next, a thermal conductor group47as shown inFIG. 13Dis prepared by integrating a plurality of thermal conductors26. The thermal conductor group47is formed by etching or pressing a metal plate made of a material having preferable thermal conductivity, such as Cu, Cu alloy, Al, Al alloy and Fe—Ni alloy in order to shape a plurality of concavities for covering a plurality of semiconductor elements11a. For facilitating a subsequent step of cutting to each semiconductor element, the inclined portions26bof the semiconductor devices to be separated are joined to form a groove in the cut region. This groove is helpful in reducing the cutting area in separating the components, thereby reducing the load applied to the semiconductor devices and to the rotary blade, and also reducing the amount of the cutting chips.

Next, as shown inFIG. 13D, the sealing resin16is injected into the concavities of the thermal conductor group47in the state where the thermal conductor group47is set so that the surface facing the semiconductor elements11ais turned upward. At this time, for the sealing resin16, a liquid resin is injected. Alternatively, a solid resin is cast and heated to be melted in the concavities of the thermal conductor group47. In a state where the surface of the lead frame27on which the semiconductor elements11aare mounted is turned downward, the lead portion29is brought into contact with the thermal conductor group47while dipping the semiconductor elements11ain the liquid sealing resin16, and thus a resin-sealing is carried out. In a case of casting a solid resin, the solid resin can be one block or more than one blocks, or a powder.

In this process where the thermal conductor group47is employed in place of the mold134used in the sealing step in the method for manufacturing a conventional semiconductor device as shown inFIG. 19D, the steps shown inFIGS. 19D and 19Eare combined into the step as shown inFIG. 13D, thereby decreasing the number of steps. In addition, the resin-sealing can be carried out without using an expensive mold. Furthermore, unlike the case of resin-sealing in a side gate method, the resin will flow less, and thus problems such as deformation of the metal thin wires15can be suppressed.

Next, as shown inFIG. 13E, the tape30is removed from the lead frame27. Finally, as shown inFIG. 13F, the inclined portion26band the lead portion29are cut off with the rotary blade42. In this manner, the semiconductor device4ais manufactured.

Though the inclined portions26bare provided to form grooves in the thermal conductor group47in this embodiment, the grooves are not formed necessarily.FIG. 14Ais a top view showing a configuration of a semiconductor device4bas a variation of the semiconductor device4a.FIG. 14Bis a cross-sectional view taken along the line H-H′ inFIG. 14A. The thermal conductor31does not have an inclined portion. This semiconductor device4bis obtained without forming a groove between the respective thermal conductors31of the thermal conductor group47.

Unlike the semiconductor device inFIG. 12B, the semiconductor device as shown inFIG. 14Bhas a thermal conductor configured without any inclined portions26b. This semiconductor device is as advantageous as the semiconductor device4ashown inFIG. 12Bin that there is no necessity of using an expensive mold and that the metal thin wires15are resistant to deformation.

When taking the heat diffusion into consideration, it is preferable that the thermal conductor26shown inFIG. 12Bis positioned in the vicinity of the lead portion29.FIG. 15Ais a top view showing a configuration of a semiconductor device4cas a variation of the semiconductor device4a.FIG. 15Bis a cross-sectional view taken along the line I-I′ inFIG. 15A. The thermal conductor32has an inclined portion32bthat extends to form a peripheral flat portion32d. The peripheral flat portion32dis adhered to the lead portion29through an insulating adhesive member33. As a result, the heat escapes from the lead portion29to the thermal conductor32, and thus the heat diffusion is improved further in comparison with the semiconductor device4a.

The method for manufacturing the semiconductor device4cwill be described below. Explanation of the steps common to those for manufacturing the semiconductor device4awill be omitted for avoiding the duplication of explanations. After connecting the semiconductor element11aand the lead portion29as shown inFIG. 13Cthrough the metal thin wire15, a thermal conductor group47bis prepared as shown inFIG. 16. The thermal conductor group47bhas a plurality of concavities, and the grooves between the concavities are flattened to form peripheral flat portions32d.

Next, the sealing resin16is injected into the concavities of the thermal conductor group47bin a state where the thermal conductor group47bis positioned so that the surface facing the semiconductor elements11ais turned upward. Next, in a state where the lead frame27is set with its surface on which the semiconductor elements11aare mounted is turned downward, the lead portion29and the thermal conductor group47bare adhered to each other through the adhesive member33while dipping the semiconductor elements11ain a liquid sealing resin16, and thus a resin-sealing is carried out. Next, the tape30is removed, and the thermal conductor group47bis cut off with the rotary blade at the flat parts of the grooves. In this manner, the semiconductor device4cis manufactured.

The semiconductor device4cconfigured as shown inFIG. 15Bis as advantageous as the semiconductor device4ain that there is no necessity of using an expensive mold, and that the metal thin wires15are resistant to deformation.

As mentioned above, since the thermal conductors are used as the sealing molds for the semiconductor devices1a-4cin Embodiments 1-4, the step of mounting the thermal conductor and the resin-sealing step can be carried out simultaneously, thereby reducing the number of steps. Moreover, the resin-sealing can be carried out without using an expensive sealing mold. As a result, there is no necessity of designing, manufacturing and maintaining the sealing mold, and thus the cost can be reduced remarkably. Furthermore, the size and the shape of the seal portion can be varied only by processing the thermal conductor, and thus the shape can be varied with further flexibility.

In addition, since the resin-sealing is carried out by dipping the semiconductor elements11aand11cin a liquid resin, deformation in the metal thin wires can be suppressed, resulting in improvement in quality.

Therefore, the present invention can provide a highly qualified semiconductor device. In other words, the semiconductor device can be shaped with less limitation, manufactured at a low cost, and it has excellent heat diffusion.

The flat portions19c,21c,23c,26c, and32care not necessarily flat, but can be hemispherical. However, preferably the flat portion23is flat since this portion is required to be in contact with the semiconductor element11c. Similarly, it is preferable that the flat portions19c,21c,23c,26c, and32care flat when a heat sink or the like is provided on such a flat portion.