JP5561072B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a method for manufacturing a resin-sealed semiconductor device.

  In recent years, with the miniaturization and multifunctionalization of electronic devices, the number of semiconductor devices mounted thereon has been increased, and the power consumption and / or heat generation density of semiconductor devices has increased. A semiconductor device generally has a resin mold package. As a package suitable for multi-terminal, for example, a quad flat package (QFP) in which lead terminals are arranged on four sides of the package, or a ball grid array (in which a ball terminal array is arranged on the lower surface of the package) BGA) type packages are known. In addition, in order to efficiently cool the semiconductor chip in the package, there is also known a type of package in which a heat sink is provided in the package and one surface thereof is exposed from the package. Further, packages such as TE (Thermally Enhanced) QFP have been developed in which a stage portion of a lead frame on which a semiconductor chip is mounted is exposed from the package to achieve low thermal resistance.

  FIG. 1 shows a schematic structure of the TEQFP type package 10. 1A is a perspective view of the package as viewed from the front surface side, FIG. 1B is a perspective view of the package as viewed from the back surface side, and FIG. 1C is a perspective view illustrating the inside of the package in a perspective view. (D) is a sectional elevation view.

  The TEQFP type package 10 is manufactured by resin-molding a lead frame on which the semiconductor chip 20 is mounted. A semiconductor chip 20 is mounted on a stage portion 31 of a lead frame, also called a die pad or a die stage, and an electrode pad on the semiconductor chip 20 is a conductor such as a gold (Au) wire on a lead portion 32 of the lead frame. 21 is connected. Thereafter, a mold resin 40 is formed so as to seal the semiconductor chip 20 and the conductor 21. In the TEQFP type package 10, the back surface of the die stage 31 is exposed from the mold resin 40. For example, the heat radiation from the semiconductor chip 20 is enhanced by bonding the die stage 31 to a motherboard or the like on which the package 10 is mounted. Can do.

  In manufacturing a semiconductor device having a resin mold package such as a TEQFP type or a BGA type, a plurality of semiconductor devices are generally manufactured simultaneously using a plurality of lead frames or substrates. That is, the semiconductor device is divided into pieces after simultaneously performing resin molding and terminal plating on a plurality of semiconductor devices. The generally sheet-like assemblies having a plurality of resin-molded packages are generally stacked and accommodated in a stack magazine for temporary storage and / or transport to subsequent processes.

  At this time, a problem as shown in FIG. 2 may occur. FIG. 2 shows, as an example, a state in which four assemblies that have finished resin molding and plating of exposed portions of the leads and the stage are stored in the stack magazine 60 in the manufacturing process of the TEQFP type package. . The transfer surface in which the exposed surface of the die stage 31 and the top surface of the mold resin 40 are in contact with each other between the stacked packages, and the die stage plating adheres to the resin surface due to, for example, vibration during transportation. Problems can arise. Such plating transfer results in poor appearance of the semiconductor device, resulting in a decrease in yield of the semiconductor device and an increase in manufacturing cost. Further, the occurrence of peeling of the plating on the die stage 31 can reduce the mounting reliability on the mother board. As described above, the contact between the mold resin and the exposed stage or the terminal between the stacked packages is due to the appearance defect of the semiconductor device and / or the mounting reliability due to vibration at the time of storing and / or transporting the stack magazine. Can be a cause of lowering.

  Regarding a BGA type or a non-lead type package such as a quad flat non-read (QFN) package, a technique for preventing the packages from contacting each other when the assembly after resin molding is stacked has been proposed. In the known technique, a resin protrusion higher than the package thickness is provided at one or more corners of the package during resin molding. These resin protrusions are formed by providing a resin reservoir or cavity communicating with the air vent at one or more corners of the package cavity of the mold, and pouring the resin into that portion. These resin protrusions are also cut from the resin package body prior to product shipment.

JP-A-10-270603 JP 2002-151625 A

  In known techniques, contact between stacked packages can be prevented by resin protrusions. However, the amount of resin used is increased by providing one or more protrusions for each package. In addition, since it is necessary to pump the protrusion-forming resin through the package cavity to the resin reservoir, it is necessary to change the pressure and / or pressurization speed at the time of resin molding compared to the case where no protrusion is provided. obtain. Furthermore, when cutting the protrusions integrally formed on the resin package, there is a risk that the outer shape of the package may vary, and a new appearance defect may occur.

  Therefore, in the manufacturing process of a semiconductor device, there is still a demand for a technique that can prevent contact between packages when a resin-molded assembly is stacked.

  According to one aspect, a method for manufacturing a semiconductor device including a step of forming a resin package for sealing a semiconductor element is provided. A runner portion connected to the resin package and a protrusion connected to the runner portion are formed together with the resin package. The protrusion extends in the thickness direction of the resin package and has a height greater than the thickness of the resin package.

  By supporting the assembly in which the protrusions formed apart from the package are stacked, contact between the packages is prevented, and appearance defects and / or deterioration of mounting reliability of the semiconductor device are avoided.

It is a figure which shows a TEQFP type semiconductor device roughly. It is sectional drawing which shows the stack of the conventional resin-molded assembly. FIG. 6 is a first diagram illustrating a typical example of a method for producing a semiconductor device. FIG. 5 is a second diagram illustrating a typical example of a method for producing a semiconductor device. It is a figure which shows an example of the sealing process of the manufacturing method of the semiconductor device which concerns on embodiment. It is a figure which expands and shows the area | region C of FIG. It is a figure which shows the assembly after a gate break. It is sectional drawing which shows the stack | stuck of the assembly of FIG. It is sectional drawing which shows the modification of the formation position of a runner part. It is sectional drawing which shows an example of a projection part. It is sectional drawing which shows one modification of a projection part.

  Hereinafter, embodiments will be described in detail with reference to the drawings. In the drawings, various components are not necessarily drawn to the same scale. Throughout the drawings, the same or corresponding components are denoted by the same or similar reference numerals.

  First, with reference to FIGS. 3 and 4, an example of a typical manufacturing method that can be used as the basis of the method for manufacturing a semiconductor device according to the embodiment will be described using the TEQFP type package 10 as shown in FIG. 1 as an example. .

  The manufacture of a TEQFP type package typically includes a plurality of semiconductor elements 20 called chips or dies separated from a semiconductor wafer, and a plurality of lead frames 30 on which the plurality of semiconductor elements 20 can be mounted. Start with. The lead frame 30 includes, as a part thereof, a stage portion (die stage) 31 on which the semiconductor element 20 is mounted and a plurality of lead portions (leads) 32 arranged so as to surround the stage portion 31. First, die bonding for mounting the semiconductor element 20 on each die stage 31 through the adhesive 21 is performed (FIG. 3A). Since the adhesive 21 constitutes a part of a heat dissipation path from the semiconductor element 20 to the outside of the package via the die stage 31, it can be preferably a heat conductive adhesive such as silver paste or solder.

  Next, each electrode pad on the semiconductor element 20 and the corresponding lead 32 are electrically connected by the conductor 22 (FIG. 3B). This step is typically performed by wire bonding a metal wire 22 such as an Au wire.

  Then, a resin package 40 for sealing the semiconductor element 20 and the conductor 22 is formed by molding (FIG. 3C). In the TEQFP type package, the lower surface of the die stage 31 is exposed from the resin package 40. In this sealing step, the lead frame 30 is sandwiched between an upper mold and a lower mold having cavities that define the resin package 40, and a mold resin such as an epoxy resin is heated and pressurized to be injected into the cavities. Is done by. By using a double-sided mold type package in which the package is formed on both sides with the lead 32 interposed therebetween, it is possible to suppress the occurrence of warping due to molding shrinkage of the mold resin. As will be described later in detail with reference to FIG. 5, this sealing step forms a runner portion connected to the resin package 40 corresponding to the resin flow path (runner) for supplying the resin into the cavity. However, the runner portion is removed by cutting a tapered connection portion generally called a gate portion (gate break).

  Next, the semiconductor package is marked on the resin package 40, such as the model number, and the lead frame exposed from the resin package 40 is plated (FIG. 4A). Thereby, the plating film 35 is formed on the lower surface of the die stage 31 and the outer lead portion of the lead 32, and low resistance and / or reliability of electrical connection with a mother board or the like can be ensured.

  Finally, individual semiconductor devices 10 are completed by dividing the lead frame 30 into a plurality of pieces and molding the outer leads (FIG. 4B).

  Next, with reference to FIGS. 5 and 6, a sealing process unique to the method for manufacturing a semiconductor device according to an embodiment will be described in more detail. FIG. 5A is a top view schematically showing the entire configuration of the lead frame 30 after resin molding, and FIG. 5B shows a B-B ′ cross section of FIG. However, in FIG. 5B, in order to facilitate understanding, components that are not on the B-B ′ cross section of FIG. FIG. 6A is an enlarged top view showing a region C in FIG. 5A, and FIG. 6B shows a D-D ′ cross section in FIG.

  As shown in FIGS. 5A and 5B, the sealing step can be performed simultaneously on one or more lead frames 30, which are two in the illustrated example. On each lead frame 30, for example, a plurality of resin packages 40 arranged in a matrix that forms a plurality of rows and columns are formed. The resin forming the resin package 40 is supplied from a cull in which a pot containing a resin material is disposed through a mold mold runner formed along the lead frame. Therefore, a sealing process forms the cull part 41 and the runner part 42 which have the resin same as this package with the resin package 40. FIG. Preferably, in order to reduce the amount of resin used, the mold is designed so that one runner portion 42 is formed for a plurality of resin packages 40. The sealing process shown in FIGS. 5 and 6 further forms a protrusion 50 connected to the runner portion 42. The protrusion 50 can be formed at the same time as the resin package 40 and the runner part 42 by providing the mold die with a protrusion forming cavity communicated with the runner.

  In the resin package cavity of the mold, for example, air vents for preventing the generation of voids in the resin package 40 are formed at three corners other than the one corner connected to the runner. Is done. The protrusion forming cavity formed according to the present embodiment is not formed in the vicinity of the air vent communicating with such a package cavity. Therefore, the formation of the protrusion 50 can be realized by simply changing the conventional mold without changing the design of the package cavity and the amount of resin press-fitted into the cavity. Further, it is not necessary to significantly change conditions such as a pressing force and / or a pressing speed during molding.

  Further, since the protrusion 50 is formed apart from the resin package 40, it is unnecessary for the semiconductor device when the package is separated from the plurality of lead frames 30 (see, for example, FIG. 4B). It is removed together with the lead frame part. Therefore, the protrusion 50 does not affect the individualization of the package, and does not cause a defective appearance of the package such as a resin burr.

  As shown in an enlarged view in FIG. 6, the protruding portion 50 is connected to the runner portion 42 via a gate portion 43 having a tapered shape similar to a gate (not shown) of the connecting portion between the runner portion 42 and the resin package 40. Can be connected to. The gate portion 43 is provided and the gate portion 43 is cut at the time of the gate break of the resin package 40, thereby removing the runner portion 42 and the cull portion 41 communicating with the runner portion 42. As shown in FIG. It becomes easy to leave 50. By this gate break, the lead frame assembly 15 having the resin protrusion 50 is obtained.

  As shown in FIG. 8, when the lead frame assembly 15 is stacked and accommodated in the stack magazine 60 or the like for temporary storage or transport to a subsequent process, the protrusion 50 is stacked between the protrusions 50. It acts to prevent the package from touching. Therefore, the height of the protrusion 50 is made larger than the thickness of the package. Therefore, for example, when the assembly 15 after the die stage and outer lead plating process (for example, see FIG. 4A) is stacked and conveyed, the upper exposed die stage 31 rubs against the top surface of the lower resin package 40. Thus, the problem that the plating is transferred is avoided.

  The layout of the protrusions 50 on the lead frame 30 is not particularly limited as long as it supports the sheet-like assembly 15 in a balanced posture and can prevent the packages from contacting each other during stacking. For example, as in the example shown in FIGS. 5 and 7, it is possible to form the protrusions 50 that are smaller than the number of packages, such as forming the protrusions 50 in two rows with respect to the resin packages 40 arranged in four rows. It is. Thereby, for example, the amount of resin used can be reduced as compared with a known technique in which one or more protrusions are provided for each package.

  The protrusions 50 are preferably formed so as to protrude from both sides of the lead frame 30. By providing a part of the protrusion 50 on both surfaces of the lead frame 30, warping of the lead frame 30 by the protrusion 50 can be suppressed or prevented. Preferably, the portion protruding from the lower surface side is formed to extend below the lower surface of the package. Thereby, also in the assembly 15 at the lowest stage of the stack, for example, the lower surface of the plated die stage 31 can be prevented from coming into contact with the stack magazine 60 or the like.

  Further, the protrusion 50 is preferably formed so as to protrude from both sides of the lead frame 30 through the opening of the lead frame 30. By penetrating the opening, it is possible to increase the strength of the protrusion 50 as compared with the case where the opening is simply brought into contact with the surface of the lead frame. Therefore, the resin-molded lead frame assembly 15 can be supported by a smaller number of protrusions 50, and the amount of resin used can be further reduced.

  5 and 6, the resin runner portion 42 is formed along the upper surface of the lead frame 30, but the runner portion 42 is formed along the lower surface side of the lead frame 30 as shown in FIG. 9. May be. In addition, the runner portions 42 can be formed on both sides of the lead frame 30.

  Next, the shape and dimensions of the protrusion 50 will be described in more detail. The protrusion 50 preferably has a shape and dimensions that do not excessively increase the amount of resin used. For example, the protrusion 50 may have a pin shape such as a generally cylindrical shape or a quadrangular prism shape. However, ensuring the mechanical strength of the protrusion 50 and that the protrusion 50 of the upper assembly 15 falls off the protrusion 50 of the lower assembly 15 during transport using a stack magazine or the like. It is necessary to prevent. From this point of view, the protrusion 50 is preferably provided so as to penetrate the opening of the lead frame 30 as described above, and is further provided on at least one surface (the upper surface in the illustrated example) of the lead frame 30. It is preferably formed wider than the diameter of the opening.

  As a preferred example, as shown in FIG. 10, the opening diameter of the lead frame 30 and the diameter of the protruding portion 51 that penetrates the lead frame 30 and protrudes to one side of the lead frame 30 are about 2 mm. The diameter of the wide portion 52 of the protruding portion protruding to the side can be about 2.5 mm. The height of the protruding portion 50 is determined according to the package thickness of the semiconductor device to be manufactured. For example, the height position of the upper end of the protruding portion 50 is the same as the height position of the top surface of the package. The height position of the lower end of 50 can be set to a position lower by about 0.5 mm than the height position of the bottom surface of the package. The connection height between the protrusion 50 and the gate 43 can be, for example, about 0.15 mm.

  Further, the protrusion 50 may have a structure that prevents the protrusion 50 from dropping between the upper stage and the lower stage when stacked. For example, as shown in FIG. 11, the protrusion 50 ′ may have a convex portion 53 at one of its upper end and lower end, and a concave portion 54 at the other. The convex portion 53 is inserted into the concave portion 54 at the time of stacking, and a side slip between the upper stage and the lower stage is prevented. Such a drop-off prevention structure allows the use of a stack magazine that does not match the size of the lead frame and / or the stack of lead frame assemblies without using a stack magazine or the like.

  Although the embodiment has been described in detail above, the present invention is not limited to the specific embodiment, and various modifications and changes can be made within the scope of the gist described in the claims. For example, in the above description, the specific embodiment has been described in detail in relation to the manufacturing method of the TEQFP type package. However, in the manufacture of other packages such as the BGA type and the non-lead type, the protrusions can be formed similarly. . For example, in the manufacture of a BGA type package, by providing the above-mentioned protrusions on a substrate such as an interposer, the contact between a terminal such as a solder ball and a resin package at the time of stacking in the manufacturing process, and consequently, the appearance of the package Damage to the terminals can be prevented.

Regarding the above description, the following additional notes are disclosed.
(Appendix 1)
A sealing step of forming a resin package for sealing the semiconductor element;
The sealing step further forms a runner portion connected to the resin package, and a protrusion connected to the runner portion and extending in the thickness direction of the resin package,
The protrusion has a height greater than the thickness of the resin package.
A method for manufacturing a semiconductor device.
(Appendix 2)
2. The method of manufacturing a semiconductor device according to appendix 1, wherein the runner portion is connected to a plurality of resin packages.
(Appendix 3)
The method of manufacturing a semiconductor device according to appendix 2, wherein the number of the protrusions connected to the runner portion is smaller than the number of the resin packages.
(Appendix 4)
Any one of appendices 1 to 3, wherein the sealing step further includes forming a gate portion at a connection portion between the runner portion and the resin package, and a connection portion between the runner portion and the projection portion. A method for manufacturing a semiconductor device according to claim 1.
(Appendix 5)
The manufacturing of the semiconductor device according to any one of appendices 1 to 4, further comprising a step of removing the runner portion so as to leave the resin package and the protruding portion after the sealing step. Method.
(Appendix 6)
The semiconductor element is mounted on the upper surface of the stage portion of the lead frame, the runner portion is formed along at least one of the upper surface and the lower surface of the lead frame, and the protrusion is formed from both the upper surface and the lower surface of the lead frame. The method for manufacturing a semiconductor device according to any one of appendices 1 to 5, wherein the semiconductor device is protruding.
(Appendix 7)
The method of manufacturing a semiconductor device according to appendix 6, wherein the protruding portion protrudes downward from a lower surface of the resin package.
(Appendix 8)
8. The method of manufacturing a semiconductor device according to appendix 6 or 7, wherein the protrusion is formed so as to penetrate the opening of the lead frame.
(Appendix 9)
The upper end of the protruding portion has one of a convex portion and a concave portion, the lower end of the protruding portion has the other of the convex portion and the concave portion, and when the lead frame having the protruding portion is stacked, the convex portion is 9. The method for manufacturing a semiconductor device according to any one of appendices 6 to 8, wherein the semiconductor device is inserted into a recess.
(Appendix 10)
The manufacturing method of a semiconductor device according to any one of appendices 6 to 9, further comprising a step of cutting a portion of the lead frame unnecessary for the semiconductor device together with the protrusion provided in the portion. Method.

DESCRIPTION OF SYMBOLS 10 Semiconductor device 15 Assembly 20 Semiconductor element 21 Adhesive 22 Metal wire 30 Lead frame 31 Die stage 32 Lead 35 Plating film 40 Resin package 41 Cull part 42 Liner part 43 Gate part 50, 50 'Protrusion part 53 Protrusion part 54 Recess of protrusion 60 Stack magazine

Claims (5)

A sealing step of forming a resin package for sealing the semiconductor element;
The sealing step further forms a runner section connected to the resin package, and a protruding portion extending in the thickness direction of the connected and the resin package to the runner,
The protrusions have a height greater than the thickness of the resin package,
The protrusion further protrudes from both the upper surface and the lower surface of the lead frame, the upper end of the protrusion has one of a protrusion and a recess, the lower end of the protrusion has the other of the protrusion and the recess, When stacking the lead frame with a protruding portion, the convex portion is inserted into the concave portion,
A method for manufacturing a semiconductor device.   2. The method of manufacturing a semiconductor device according to claim 1, wherein the number of the protrusions connected to the runner part is smaller than the number of the resin packages connected to the runner part. Said semiconductor element is mounted on the upper surface of the stage portion of said lead frame, said runner section according to claim 1 or 2, characterized in that, formed along at least one of the upper and lower surfaces of the lead frame A method for manufacturing a semiconductor device. The protrusions method of manufacturing a semiconductor device according to any one of claims 1 to 3 wherein protrudes from the lower surface of the resin package to the lower, it is characterized. The method of manufacturing a semiconductor device according to the projections any one of claims 1 to 4, characterized in that is formed to penetrate through the openings of the lead frame.