This application is based on Japanese Patent Application No. 2006-101933 filed on Apr. 3, 2006, and No. 2006-351725 filed on Dec. 27, 2006, the disclosures of which are incorporated herein by reference.
The present invention relates to a semiconductor device having a heat radiation member and a semiconductor chip and a method for manufacturing the same.
A semiconductor device having a pair of heat radiation members and a semiconductor chip is disclosed in, for example, Japanese Patent No. 3525832. The heat radiation members are connected to the semiconductor chip thermally and electrically. Each heat radiation member includes a heat radiation surface. Specifically, two semiconductor chips are arranged on a same plane, and the heat radiation members sandwich both semiconductor chips. Each chip includes a main electrode, which is connected to the heat radiation members thermally and electrically with a bonding member such as a solder member. A resin mold covers the device such that the heat radiation surface of each heat radiation member is exposed from the resin mold. Each semiconductor chip is controlled with a signal inputted from an external circuit through a control terminal.
In the above device, the heat radiation members and the control terminal are integrated. However, the thickness of each heat radiation member is different from the thickness of the control terminal. Accordingly, the device is formed from a deformed member. The deformed member is obtained in such a manner that a rolled member is plastically deformed and/or the surface of a metallic plate is cut. Alternatively, the heat radiation members and the control terminal are independently prepared, and then, they are crimped.
In the above device, since the heat radiation members and the control terminal are integrated, the following problems occur.
First, it is necessary to integrate the heat radiation members and the control terminal. Accordingly, when the deformed member is prepared, the rolled metallic member is plastically deformed. Thus, a processing strain caused by the plastic deformation is formed in the deformed member. Thus, the heat radiation member may warp, and deviation from flatness on the heat radiation surface of the heat radiation member becomes high. Further, since the heat radiation members sandwich the semiconductor chip, it is difficult to keep parallelism between the heat radiation surfaces of the heat radiation members.
The deviation from flatness of the heat radiation surface and the parallelism between the heat radiation surfaces affect the heat radiation performance of the heat radiation member. Accordingly, it is required to control the deviation from flatness and the parallelism with accuracy smaller than 100 μm or 50 μm. However, when the deformed member is deformed, the deviation from flatness is increased and the parallelism is reduced. Thus, the heat radiation performance is also reduced.
When the heat radiation members and the control terminal are crimped, it is necessary to process metallically the heat radiation member for crimping. This metallic processing may affect the deviation from flatness and the parallelism of the heat radiation member. Thus, the heat radiation performance is also reduced.
Further, it is difficult to select the materials of the heat radiation member and the control terminal. Specifically, it is required for the material of the heat radiation member to have sufficient electric conductivity and heat conductivity. It is required for the material of the control terminal to have mechanical strength, bending performance and/or positioning accuracy of an outer lead. However, by processing the rolled member and/or the metallic plate, the heat radiation member and the control terminal are integrated so that the deformed member is prepared. Accordingly, it is difficult to meet the above requirements. For example, when the heat radiation member is made of pure copper such as Japanese Industrial Standards C1020 having a softening point of 200° C., the Hv hardness of the control terminal becomes insufficient. Thus, stability of the shape of the control terminal and press workability of the control terminal are reduced. Here, it is considered that different materials are prepared, and then, they are crimped. However, this method may affect the metallic processing.
Further, when the semiconductor device is manufactured, a pair of heat radiation members is soldered through the semiconductor chip. In this case, solder wettability and a gravity center position of mounted elements may cause the thickness of the semiconductor device and the parallelism of each heat radiation member to deviate. It is important to maintain the dimensional accuracy. Thus, it is necessary to keep the positioning of the pair of heat radiation members to have predetermined dimensions, i.e., to have a predetermined distance between the heat radiation members. In view of this point, in Japanese Patent No. 3620399, the semiconductor chip is sandwiched between the heat radiation members with keeping the parallelism of the heat radiation surfaces of the pair of heat radiation members. However, in this case, it is required for the heat radiation member to have a complicated shape for keeping the parallelism. Thus, when the shape of the heat radiation member is complicated, the processing may affect the heat radiation member and the control member; and therefore, the shape accuracy of them is reduced.
Thus, it is required to keep parallelism and to reduce deviation from flatness in a pair of heat radiation members.
In view of the above-described problem, it is an object of the present disclosure to provide a semiconductor device having a heat radiation member and a semiconductor chip. It is another object of the present disclosure to provide a method for manufacturing a semiconductor device having a heat radiation member and a semiconductor chip.
According to a first aspect of the present disclosure, a method for manufacturing a semiconductor device having a semiconductor chip, first and second heat radiation members and a connection terminal, wherein the first and second heat radiation members sandwich the semiconductor chip so that the first and second heat radiation members radiate heat generated in the semiconductor chip, and wherein the connection terminal connects the semiconductor chip and the first and second heat radiation members, and electrically connects to an external circuit, the method comprising: preparing a plate shaped lead frame having first and second suspended terminals and the connection terminal; bending the first suspended terminal to a first side of the lead frame, and bending the second suspended terminal to a second side of the lead frame so that a distance between the first and second suspended terminals in a direction perpendicular to the lead frame is set to be a predetermined distance; preparing the first heat radiation member to face the first side of the lead frame, and preparing the second heat radiation member to face the second side of the lead frame, wherein each of the first and second heat radiation members is independently prepared from the lead frame; mounting the semiconductor chip on the first heat radiation member to contact a first side of the semiconductor chip and an inner surface of the first heat radiation member, press-contacting the first suspended terminal to the first heat radiation member, and bonding the semiconductor chip together with the connection terminal to the first heat radiation member; and preparing an assembling jig having a base and a cover, mounting the first heat radiation member on the base after the bonding the semiconductor chip together with the connection terminal to the first heat radiation member, arranging the second heat radiation member on the second suspended terminal to contact an inner surface of the second heat radiation member and a mounting surface of the second suspended terminal, pressing the second heat radiation member with the cover toward the base in such a manner that a heat radiation surface of the second heat radiation member is parallel to a heat radiation surface of the first heat radiation member, and bonding a second side of the semiconductor chip and the inner surface of the second heat radiation member under a condition where the second suspended terminal press-contacts the second heat radiation member by a reaction force of a spring function of the second suspended terminal. A distance between the inner surface of the first heat radiation member and the mounting surface of the second suspended terminal is larger than a distance between the inner surface of the first heat radiation member and the second side of the semiconductor chip after the bonding the semiconductor chip together with the connection terminal to the first heat radiation member.
In the above method, it is not necessary to prepare the heat radiation members, which is plastically deformed. Thus, the heat radiation member does not warp, so that the deviation from flatness of the heat radiation members is reduced. Further, by using the reaction force of the suspended terminals, the parallelism of the heat radiation members is improved, so that the dimensional accuracy of the heat radiation surfaces of the heat radiation members is improved.
According to a second aspect of the present disclosure, a semiconductor device includes: a semiconductor chip; first and second heat radiation members for sandwiching the semiconductor chip and radiating heat generated in the semiconductor chip, wherein the first and second heat radiation members are electrically coupled with the semiconductor chip; a connection terminal coupled with each heat radiation member and electrically coupled with an external circuit, wherein the connection terminal is a different body from the first and second heat radiation members; and a resin mold for sealing the first and second heat radiation members and the connection terminal.
In the above device, since the connection terminal is a different body from the first and second heat radiation members, the heat radiation members can be prepared without performing a plastically deformed method. Thus, the dimensional accuracy and the deviation from flatness of the heat radiation members are improved. Thus, dimensional accuracy and positioning accuracy of each element in the device are also improved.
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:
A semiconductor device S1 according to a first embodiment is shown in
In the device S1, a first semiconductor chip 21 is mounted on a first heat radiation member 11, and a second heat radiation member 12 is disposed on the first semiconductor chip 21 with a first heat radiation block 31. A gate electrode of the first semiconductor chip 21 is coupled with a control signal terminal 50 through a gate wire 40. The first radiation member 11 is connected to a first main terminal 61, and the second radiation member 12 is connected to a second main terminal 62.
A second semiconductor chip 22 is mounted on the first heat radiation member 11 such that the first semiconductor chip 21 and the second semiconductor chip 22 are arranged in parallel each other. The second heat radiation member 12 is disposed on the second semiconductor chip 22 with a second heat radiation block 32. Both sides of each chip 21, 22 have electrodes, respectively.
The first semiconductor chip 21 includes, for example, FWD (i.e., free wheel diode) and the like. The second semiconductor chip 22 includes, for example, a power semiconductor element such as an IGBT (insulated gate bipolar transistor) and a thyristor.
The control signal terminal 50 and the first and second main terminals 61, 62 are leads for inputting a signal from an external circuit into the chips 21, 22. The control signal terminal 60 and the first and second main terminals 61, 62 are formed from a lead frame 70 made of heat resistant copper alloy, copper, aluminum, or alloy of them. The lead frame 70 is a plate.
A bonding member 80 is disposed among the first and second heat radiation members 11, 12, the first and second semiconductor chips 21, 22, and the first and second heat radiation blocks 31, 32 so that elements are electrically and thermally coupled each other. Another bonding member 81 is disposed between the first main terminal 61 and the first heat radiation member 11 and between the second main terminal and the second heat radiation member 12 so that the first main terminal 61 is electrically connected to the first heat radiation member 11, and the second main terminal 62 is electrically connected to the second heat radiation member 12. The bonding members 80, 81 are made of solder or conductive adhesive material. In this embodiment, the bonding members 80, 81 are made of tin series solder. Alternatively, the bonding members 80, 81 are made of silver paste.
Each heat radiation member 11, 12 functions as a heat radiation plate for discharging heat generated in the semiconductor chip 21, 22. Thus, the heat radiation member 11, 12 is made of excellent heat conductive material having low resistance such as copper or aluminum. Each heat block 31, 32 conducts the heat generated in the semiconductor chip 21, 22 to the second heat radiation member side. Each heat block 31, 32 is made of pure copper or the like.
The heat radiation members 11, 12 and the heat radiation blocks 31, 32 are formed from a metallic plate by a press working method. Since the plate is merely pressed, processing strain and stress are not substantially formed in the heat radiation members 11, 12 and the heat radiation blocks 31, 32. Thus, the shape accuracy of the heat radiation members 11, 12 and the heat radiation blocks 31, 32 is comparatively high. Further, by maintaining the heat radiation performance of each heat radiation member 11, 12, it is preferred that the parallelism of the heat radiation surface is high. The parallelism is defined as roughness of the heat radiation surface. When the parallelism is high, the roughness is small. Thus, it is preferred that the roughness of the heat radiation surface of each heat radiation member 11, 12 is smaller than 100 μm or 50 μm.
Accordingly, on the top side of each semiconductor chip 21, 22, the heat is discharged through the heat radiation block 31, 32 and the second heat radiation member 12. On the bottom side of each semiconductor chip 21, 22, the heat is discharged through the first heat radiation member 11.
As shown in
Further, as shown in
A part of each suspended terminal 71-76 is folded in order to maintain the parallelism between the first and second heat radiation members 11, 12 when the device S1 is manufactured. Further, since the suspended terminal 71-76 is merely connected to the heat radiation member 11, 12, the operation of the device S1 is not directly affected. The parallelism is defined as a degree of tilt of one heat radiation surface of the heat radiation members 11, 12 with reference to the other heat radiation surface. When the parallelism is high, the degree of tilt is small.
One side of the first heat radiation member 11, one side of the second heat radiation member 12, a part of the control signal terminal 50, a part of the first main terminal 61 and a part of the second main terminal 62 are exposed from a resin mold 90. Here, the control signal terminal 50 and the first and second main terminals 61, 62 provide a connection terminal.
A method for manufacturing the device S1 is described with reference to
In
Preferably, each suspended terminal 71-76 formed in the lead frame 70 can have a spring function even when the lead frame 70 is disposed under a temperature in a reflow process. In view of this, the lead frame 70 is made of a certain material for securing the spring function of the suspended terminals 71-76. Specifically, the material of the lead frame 70 has a softening point, which is higher than atemperature, at which the suspended terminals 71-76 are bonded to the heat radiation members 11, 12. Thus, it is preferred that the softening point of the lead frame 70 is higher than a reflow temperature. For example, the lead frame 70 is made of copper, aluminum or alloy of them.
When the lead frame 70 and the first and second heat radiation members 11, 12 are bonded, the first to sixth suspended terminals 71-76 control the positioning of each heat radiation member 11, 12 and a distance between the first and second heat radiation members 11, 12, and adjust the parallelism between the heat radiation surfaces of the heat radiation members 11, 12. As shown in
As shown in
As shown in
The bending portion 70a of each of the main terminals 61, 62 and the suspended terminals 71-76 is formed such that the top portion of the main terminals 61, 62 or the suspended terminals 71-76 is pressed toward the one side or the other side of the lead frame 70.
A surface treatment is performed on the top portion of each of the main terminals 61, 62 and the suspended terminals 71-76 in order to bond the top portion to the heat radiation member 11, 12. Specifically, the bonding member 81 is formed on the top portion of each of the main terminals 61, 62 and the suspended terminals 71-76. The bonding member 81 is disposed on the top portion such that the bonding member 81 faces the heat radiation member 11, 12. If necessary, whole of the top portion may be coated with a plating nickel film.
The control signal terminal 50 and the main terminals 61, 62 are wires for electrically connecting to an external circuit. Accordingly, the material of control signal terminal 50 and the main terminals 61, 62 has excellent conductivity. It is preferred that the control signal terminal 50 and the main terminals 61, 62 are made of copper, aluminum or alloy of them. When it is required for the control signal terminal 50, the main terminals 61, 62 and the suspended terminals 71-76 to have bendable property and heat resistance, they may be made of alloy or the like having these properties.
In
A nickel coating may be formed on the surface of the first heat radiation member 11. The first heat radiation member 11 may have a softening point, which is lower than a reflow temperature in a reflow process, as long as the first heat radiation member 11 has sufficient heat conductivity. The second heat radiation member 12 may also have the nickel coating thereon, and have the softening point lower than the reflow temperature. Preferably, the softening point of each of the first and second heat radiation members 11, 12 is lower than a temperature, at which the suspended terminals 71-76 are bonded to the heat radiation members 11, 12.
As shown in
Thus, the first heat radiation member 11 together with the semiconductor chips 21, 22 and the heat radiation blocks 31, 32 mounted thereon is prepared. The lead frame shown in
The above lead frame 70 with the first heat radiation member 11 is reflowed at 280° C., for example, so that the bonding member 80 is melt. Thus, the semiconductor chips 21, 22 and the heat radiation blocks 31, 32 are bonded together. Further, the semiconductor chips 21, 22 and the first heat radiation member 11 are bonded together. Furthermore, the first, second and sixth suspended terminals 71, 72, 76, the first main terminal 61 and the first heat radiation member 11 are bonded together.
After the above reflow process, as shown in
Specifically, a distance between the reference surface of the first heat radiation member 11 and the one side of each of the third to fifth suspended terminals 73-75 is defined as H1. A distance between the reference surface and the one side of the first heat radiation block 31 is defined as H2. The suspended terminals 71-76 and the main terminals 61, 62 are bent from the lead frame 70 so that the distance H1 is larger than the distance H2.
When the lead frame 70 is formed, and the lead frame 70 is bonded to the first heat radiation member 11, the bending portion 70a is formed by bending the suspended terminals 71-76 and the main terminals 61, 62 in order to have the relationship such that the distance H1 is larger than the distance H2.
In
In
One surface of each of the cover 130 and the base 110, which press-contacts the heat radiation members 11, 12, is flattened. Thus, the deviation from flatness in the cover 130 and the base 110 is comparatively small. Multiple supports 120 have the same height from the surface of the base 110, on which the first heat radiation member 11 is mounted. The height of each support 120 defines the distance between the first and second heat radiation members 11, 12 when the lead frame 70 is mounted on the second heat radiation member 12. Thus, the height of the support 120 corresponds to the distance between the heat radiation surfaces of the first and second heat radiation members 11, 12 in the device S1 shown in
First, the lead frame 70 is mounted on the assembling jig 100 after the process shown in
The top portion of each of the suspended terminals 71-76 and the main terminals 61, 62 has a spring function since the top portion has the bending portion 70a. The elastic force of the spring function generates a reaction force. Specifically, the first, second and sixth suspended terminals 71, 72, 76 and the first main terminal 61, which are bent toward the one side of the lead frame 70, receives the reaction force toward the first heat radiation member side. The third to fifth suspended terminals 73-75 and the second main terminal 62 receives the reaction force toward the second heat radiation member side. Thus, the first heat radiation member 11 is pressed toward the base 110, and the second heat radiation member 12 is pressed toward the cover 130.
Each support 120 has the same height, and the deviation from flatness on the surface of each of the base 110 and the cover 130 is small, the surface which presses the heat radiation members 11, 12. Accordingly, when the cover 130 press-contacts the supports 120, the parallelism between the base 110 and the cover 130 is kept.
Thus, by using the reaction force of the suspended terminals 71-76 and the main terminals 61, 62 in the lead frame 70, the heat radiation members 11, 12 press the base 110 and the cover 130. The parallelism between the heat radiation surfaces of the heat radiation members 11, 12 is kept. The distance between the heat radiation surfaces can be adjusted by the height of the supports 120.
When the lead frame 70 is manufactured, the bending portion 70a of each of the suspended terminals 71-76 and the main terminals 61, 62 is formed under the above described conditions. Thus, by using the spring function of the suspended terminals 71-76 and the main terminals 61, 62, the parallelism between the heat radiation surfaces is kept.
Further, the cover 130 press-contacts the supports 120, and the weight 140 is arranged on the cover 130 so that the load is applied to the cover 130. Then, the lead frame 70 is reflowed at 280° C. The posture and the positioning among the suspended terminals 71-76, the main terminals 61, 62, and the heat radiation members 11, 12 are maintained, and the first, second and sixth suspended terminals 71, 72, 76, the second main terminal 62, the heat radiation blocks 31, 32 and the second heat radiation member 12 are bonded together. Then, the product is removed from the assembling jig 100. Thus, the product shown in
In
Thus, the product is molded with the resin mold 90, so that each element is fixed in the resin mold 90 with maintaining the posture and the positioning among the heat radiation members 11, 12, the lead frame 70 and the like.
In
As shown in
Then, electrical conduction test and appearance test of the device S1 is performed. After that, the device S1 is shipped.
In this embodiment, the lead frame 70 and the first and second heat radiation members 11, 12 are independently prepared. Further, by using the spring function of the suspended terminals 71-76 formed in the lead frame 70, the device S1 is manufactured. In this case, it is not necessary to plastically deform the heat radiation member 11, 12. Thus, the heat radiation member 11, 12 is prepared without including a processing strain. Accordingly, the heat radiation member 11, 12 has no warpage caused by the processing strain. The deviation from flatness of each heat radiation member 11, 12 is improved.
Further, since the top portions of the suspended terminals 71-76 and the main terminals 61, 62 are bent, by using the reaction force of the suspended terminals 71-76 and the main terminals 61, 62, the heat radiation members 11, 12 press-contact the base 110 and the cover 130, which are arranged to be in parallel each other by using the supports 120. Thus, the parallelism between the heat radiation surfaces is maintained. Accordingly, the top portions of the suspended terminals 71-76 and the main terminals 61, 62 are bent so that they have the spring function. The elastic force of the spring function provides to maintain the parallelism between the heat radiation surfaces.
Thus, the parallelism between the first and second heat radiation members 11, 12 is improved, and further, the deviation from flatness on the heat radiation surfaces is improved.
As shown in
Since each suspended terminal 73-75 has the sidewall 73a, the second heat radiation member 12 can be positioned appropriately without using a positioning jig. This sidewall 73a is formed together with forming the suspended terminals 73-75 from the lead frame 70 by a press working method.
The first, second and sixth suspended terminals 71, 72, 76 for connecting to the first heat radiation member 11 may have sidewalls similar to the sidewall 73a shown in
In the lead frame 70, the shape of each of the eighth suspended terminal 77b and the ninth suspended terminal 77c is maintained by forming the eighth and ninth suspended terminals 77b, 77c and the connection bars 77e, 77f to connect the control signal terminal side and the main terminals side. The lead frame 70 is formed by a press-working method or the like. Thus, the lead frame 70 may be used for the semiconductor device S1.
Although the device S1 includes the seventh and eighth suspended terminals 77a, 77b, the positional relationship between the first heat radiation member 11 and the seventh and eighth suspended terminals 77a, 77b shown in
When the device S1 is mounted on an external circuit board or the like, the metallic plate 11c, 12c exposed from the resin mold 90 is insulated from the metallic plate 11a, 12a disposed in the resin mold 90 by the insulation plate 11b, 12b. Thus, the device S1 is electrically insulated from the external circuit board. Although the first and second heat radiation members 11, 12 include the insulation plates 11b, 12b, the first and second heat radiation members 11, 12 may include insulation resin layers.
Further, each heat radiation members 11, 12 may be formed from two layers, which are composed of the metallic plate 11a, 12a and the insulation plate 11b, 12b. Further, each heat radiation members 11, 12 may be formed from two layers, which are composed of the metallic plate 11a, 12a and the insulation resin layer.
(Modifications)
The device S1 may not have the heat radiation block 31, 32. In this case, when the lead frame 70 is mounted in the assembling jig 100, the suspended terminals 71-76 and the main terminals 61, 62 are formed such that a distance between the reference surface of the first heat radiation member 11 and the surface of each of the suspended terminals 73-75 and the second main terminal 62 is larger than a distance between the reference surface of the first heat radiation member 11 and the surface of each semiconductor chip 21, 22. Here, the distance between the reference surface and the surface of each of the suspended terminals 73-75 and the second main terminal 62 corresponds to the distance H1, and the distance between the reference surface and the surface of each semiconductor chip 21, 22 corresponds to the distance H2. The surface of each of the suspended terminals 73-75 and the second main terminal 62 faces the second heat radiation member 12, and the surface of each semiconductor chip 21, 22 faces the second heat radiation member 12. Further, the number of the suspended terminals 71-76 may be one or more.
Each suspended terminal 71-78 includes the bending portion 70a shown in
The suspended terminal 71-76 and the heat radiation member 11, 12 are coupled with the bonding member 81. Alternatively, the suspended terminal 71-76 may merely contact or press-contact the heat radiation member 11, 12. In this case, the heat radiation members 11, 12 can be supported by the reaction force of the spring function of the suspended terminals 71-76. Here, the suspended terminals 71-76 directly contact the heat radiation members 11, 12 without using the bonding member 81.
The above disclosure has the following aspects.
According to a first aspect of the present disclosure, a method for manufacturing a semiconductor device having a semiconductor chip, first and second heat radiation members and a connection terminal, wherein the first and second heat radiation members sandwich the semiconductor chip so that the first and second heat radiation members radiate heat generated in the semiconductor chip, and wherein the connection terminal connects the semiconductor chip and the first and second heat radiation members, and electrically connects to an external circuit, the method comprising: preparing a plate shaped lead frame having first and second suspended terminals and the connection terminal; bending the first suspended terminal to a first side of the lead frame, and bending the second suspended terminal to a second side of the lead frame so that a distance between the first and second suspended terminals in a direction perpendicular to the lead frame is set to be a predetermined distance; preparing the first heat radiation member to face the first side of the lead frame, and preparing the second heat radiation member to face the second side of the lead frame, wherein each of the first and second heat radiation members is independently prepared from the lead frame; mounting the semiconductor chip on the first heat radiation member to contact a first side of the semiconductor chip and an inner surface of the first heat radiation member, press-contacting the first suspended terminal to the first heat radiation member, and bonding the semiconductor chip together with the connection terminal to the first heat radiation member; and preparing an assembling jig having a base and a cover, mounting the first heat radiation member on the base after the bonding the semiconductor chip together with the connection terminal to the first heat radiation member, arranging the second heat radiation member on the second suspended terminal to contact an inner surface of the second heat radiation member and a mounting surface of the second suspended terminal, pressing the second heat radiation member with the cover toward the base in such a manner that a heat radiation surface of the second heat radiation member is parallel to a heat radiation surface of the first heat radiation member, and bonding a second side of the semiconductor chip and the inner surface of the second heat radiation member under a condition where the second suspended terminal press-contacts the second heat radiation member by a reaction force of a spring function of the second suspended terminal. A distance between the inner surface of the first heat radiation member and the mounting surface of the second suspended terminal is larger than a distance between the inner surface of the first heat radiation member and the second side of the semiconductor chip after the bonding the semiconductor chip together with the connection terminal to the first heat radiation member.
In the above method, it is not necessary to prepare the heat radiation members, which is plastically deformed. Thus, the heat radiation member does not warp, so that the deviation from flatness of the heat radiation members is reduced. Further, by using the reaction force of the suspended terminals, the parallelism of the heat radiation members is improved, so that the dimensional accuracy of the heat radiation surfaces of the heat radiation members is improved.
Alternatively, the bonding the semiconductor chip together with the connection terminal to the first heat radiation member may include bonding the first suspended terminal to the first heat radiation member. The bonding the second side of the semiconductor chip and the inner surface of the second heat radiation member includes bonding the second suspended terminal to the second heat radiation member, and the lead frame is made of a material having a softening point, which is higher than a temperature at the bonding the first suspended terminal to the first heat radiation member and a temperature at the bonding the second suspended terminal to the second heat radiation member. In this case, the lead frame is not softened when the suspended terminals are bonded to the heat radiation members. Thus, the mechanical strength of the lead frame is improved. Accordingly, when the lead frame is bonded to the second heat radiation member, the reaction force of the suspended terminals is improved.
Alternatively, the bonding the semiconductor chip together with the connection terminal to the first heat radiation member may include bonding the first suspended terminal to the first heat radiation member. The bonding the second side of the semiconductor chip and the inner surface of the second heat radiation member includes bonding the second suspended terminal to the second heat radiation member. The first heat radiation member is made of a material having a first softening point, and the second heat radiation member is made of a material having a second softening point, and the first and second softening points are lower than a temperature at the bonding the first suspended terminal to the first heat radiation member and a temperature at the bonding the second suspended terminal to the second heat radiation member.
Alternatively, the method may further includes: sealing the semiconductor chip with a resin mold in such a manner that the heat radiation surface of the first heat radiation member, the heat radiation surface of the second heat radiation member and a part of the connection terminal are exposed from the resin mold after the bonding the second side of the semiconductor chip and the inner surface of the second heat radiation member; and removing a part of the lead frame other than the part of the connection terminal after the sealing the semiconductor chip with the resin mold, wherein the part of the lead frame is exposed from the resin mold. Further, the lead frame may further include an opening for accommodating the semiconductor chip. The mounting the semiconductor chip on the first heat radiation member includes mounting the lead frame on the first heat radiation member in such a manner that the semiconductor chip is disposed in the opening of the lead frame. The bonding the semiconductor chip together with the connection terminal to the first heat radiation member further includes bonding the connection terminal to the semiconductor chip with a wire. The bonding the second side of the semiconductor chip and the inner surface of the second heat radiation member further includes bonding the connection terminal to the second heat radiation member. Furthermore, the lead frame may further include a tie bar for connecting among the first and second suspended terminals and the connection terminal, and in the removing a part of the lead frame other than the part of the connection terminal, the tie bar is removed from the lead frame so that the first and second suspended terminals and the connection terminal remain in the semiconductor device. Further, after the tie bar is removed from the lead frame, the first and second suspended terminals and the another part of the connection terminal may be independently disposed in the resin mold, and the first and second suspended terminals may be isolated from the semiconductor chip and the connection terminal.
According to a second aspect of the present disclosure, a semiconductor device includes: a semiconductor chip; first and second heat radiation members for sandwiching the semiconductor chip and radiating heat generated in the semiconductor chip, wherein the first and second heat radiation members are electrically coupled with the semiconductor chip; a connection terminal coupled with each heat radiation member and electrically coupled with an external circuit, wherein the connection terminal is a different body from the first and second heat radiation members; and a resin mold for sealing the first and second heat radiation members and the connection terminal.
In the above device, since the connection terminal is a different body from the first and second heat radiation members, the heat radiation members can be prepared without performing a plastically deformed method. Thus, the dimensional accuracy and the deviation from flatness of the heat radiation members are improved. Thus, dimensional accuracy and positioning accuracy of each element in the device are also improved.
Alternatively, the semiconductor device may further include first and second suspended terminals for maintaining a positioning relationship between the first and second heat radiation members. The first suspended terminal is disposed on the inner surface of the first heat radiation member, and the second suspended terminal is disposed on the inner surface of the second heat radiation member. Further, each suspended terminal may be sealed with the resin mold, and each suspended terminal may have an end, which is a tie-bar cut end at an edge of the resin mold. Further, each suspended terminal may be made of a material having a softening point, which is higher than a bonding temperature of each heat radiation member to the semiconductor chip, a bonding temperature of each heat radiation member to the suspended terminal, or a bonding temperature of each heat radiation member to the connection terminal. Further, each heat radiation member may have a softening point, which is lower than a bonding temperature of the heat radiation member to the suspended terminal. Further, the second suspended terminal may have a mounting surface, which contacts the inner surface of the second heat radiation member, and the semiconductor chip may have a first side contacting the inner surface of the first heat radiation member and a second side contacting the inner surface of the second heat radiation member. A distance between the inner surface of the first heat radiation member and the mounting surface of the second suspended terminal is larger than a distance between the inner surface of the first heat radiation member and the second side of the semiconductor chip. Furthermore, the first suspended terminal may include a bending portion, which is bent toward the inner surface of the first heat radiation member. The second suspended terminal includes a bending portion, which is bent toward the inner surface of the second heat radiation member. The bending portion of the first suspended terminal provides a spring function for press-contacting the first heat radiation member. The bending portion of the second suspended terminal provides a spring function for press-contacting the second heat radiation member. Furthermore, the first and second suspended terminals may be sealed with the resin mold. The first suspended terminal has one end contacting the first heat radiation member and an opposite end. The opposite end of the first suspended terminal is a tie-bar cut end. The second suspended terminal has one end contacting the second heat radiation member and an opposite end. The opposite end of the second suspended terminal is a tie-bar cut end.
While the invention has been described with reference to preferred embodiments thereof, it is to be understood that the invention is not limited to the preferred embodiments and constructions. The invention is intended to cover various modification and equivalent arrangements. In addition, while the various combinations and configurations, which are preferred, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the invention.
Number | Date | Country | Kind |
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2006-101933 | Apr 2006 | JP | national |
2006-351725 | Dec 2006 | JP | national |