JP2011096830A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device capable of at least reducing warpage of a substrate by suppressing a temperature change on upper and lower surfaces of the substrate due to heat generation in using the semiconductor device, and accordingly capable of effectively suppressing fatigue failure of a solder layer joining the substrate and a semiconductor package. <P>SOLUTION: In a semiconductor device 100, a semiconductor package 10 comprising a semiconductor element 1, a heat dissipation pad 3 and a sealing resin 7 for sealing the semiconductor element and the heat dissipation pad is joined to a substrate 8 via a solder layer 93. A through-hole 81 extending from one surface 8a facing the semiconductor package 10 to another surface 8b is formed at a position at least corresponding to the heat dissipation pad 3 in the substrate 8, and the through-hole 81 is closed with a heat conductive material having a relatively high thermal conductivity as compared with the substrate 8. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a semiconductor device, and more particularly, suppresses or reduces at least the warpage of a substrate caused by heat generation when the semiconductor device is used. The present invention relates to a semiconductor device capable of effectively suppressing peeling.

  In recent years, with the increase in functionality, performance, and miniaturization of electronic product products, there is a demand for miniaturization of semiconductor components inside the product. High-density mounting of a semiconductor package on a semiconductor substrate and the semiconductor package itself Densification is attempted. However, with the miniaturization (thinning) and high density of the semiconductor package, the temperature of the semiconductor package when the semiconductor device is used increases, and the temperature difference between the upper and lower surfaces of the semiconductor package and the substrate increases. In particular, when the temperature difference between the upper and lower surfaces of a highly rigid substrate increases and the deformation (warpage) of the substrate increases due to this temperature difference, the semiconductor device may fail, such as peeling off the solder layer that connects the substrate and the semiconductor package. This is one of the important solutions in this field.

  By the way, along with the downsizing (thinning) of semiconductor packages, leadless type surface mount semiconductor packages have recently been introduced into the market, such as BGA packages (Ball Grid Array) and CSPs (Clip Size Packages). Is an example. In the surface mount type package, part or all of the electrode terminals are not sealed in the resin, but are exposed on the bottom and side surfaces of the semiconductor package, and lead wires are not taken out, so that the mounting area can be reduced.

  Further, from the viewpoint of improving the heat dissipation of the semiconductor package, a semiconductor package having a structure in which a heat sink is provided on the mounting surface of the substrate has been recently introduced. More specifically, there is a structure in which a part of a die pad (heat dissipating pad) having a function of a heat sink is exposed without being sealed in a resin, or a structure in which a separate heat sink is built in. In addition, having a heat dissipation plate improves heat dissipation and is suitable for mounting a semiconductor element that generates a large amount of heat.

  FIGS. 8 and 9 show an embodiment of a semiconductor device in which a semiconductor package of the leadless type described above and having a structure in which a part of the heat dissipating pad is exposed is mounted on a substrate. 8 is a longitudinal sectional view thereof, and FIG. 9 is a view taken along arrow IX-IX in FIG.

  8 and 9, a semiconductor element a is mounted on a heat-dissipating pad c in a posture bonded by a die bonding material b such as a conductive adhesive, and electrodes d1, d2 (the outermost peripheral side is d1) and a conductive wire e. Electrically connected. Further, the semiconductor element a, the heat dissipating pad c, the electrodes d1, d2, and the conductive wire e are integrally sealed with the sealing resin body f so that a part of both the heat dissipating pad c and the electrodes d1, d2 are exposed. A semiconductor package P is formed. In this semiconductor package P, the exposed portion of both the heat dissipating pad c and the electrodes d1, d2 and the substrate g are joined by the solder layer h, whereby the semiconductor device H is formed.

  By the way, in the conventional semiconductor device H as shown in FIGS. 8 and 9, the temperature difference between the upper and lower surfaces of the substrate g is generated by the heat generated from the semiconductor element a when the semiconductor device H is used, and accordingly, the substrate g It is known that warping of the base g occurs because the difference in expansion between the upper and lower surfaces changes.

  That is, as shown in FIG. 8, in the semiconductor package P in which the semiconductor element a is disposed at a substantially central position of the semiconductor package P, the substrate g is convex toward the semiconductor element a side of the substrate g. A deformation mode (a chain line in FIG. 8) that warps in the opposite direction with respect to the semiconductor package P in the vicinity of the electrodes d1 and d2 at the separated positions.

  By this deformation mode, a shearing force or a tensile force acts on the solder layer h connecting the electrodes d1 and d2 disposed on the outer periphery of the semiconductor package P and the substrate g, and the solder layer h is likely to be peeled off or cracked. The wiring pattern of the substrate g is easily peeled off.

  As one of the invention techniques for solving the various problems described above, a semiconductor device disclosed in Patent Document 1 can be cited. Since this semiconductor device includes a through hole in a substrate on which a semiconductor package is mounted, and this through hole is arranged at a position corresponding to the semiconductor package, heat generated when the semiconductor device is used is transferred to the back surface of the substrate through the through hole ( By exhausting heat to the surface opposite to the mounting surface of the semiconductor package, warping of the substrate can be suppressed.

JP 2003-297965 A

  In the semiconductor device disclosed in Patent Document 1, a semiconductor package containing a power device is connected to the surface of a glass-epoxy substrate via a solder layer. Also, a copper heat sink is embedded in the mounting surface of the semiconductor package, and a part of the heat sink is exposed on the mounting surface of the semiconductor package. Further, on this substrate, a plurality of through holes are aligned and arranged at substantially equal intervals in a vertical and horizontal direction (in a lattice pattern) in a range where the semiconductor package is mounted. Each through hole is provided with a hole conductor, and each hole conductor has a cylindrical portion covering the inner wall of the through hole, and one end of the cylindrical portion, followed by the surface of the substrate (the surface on which the semiconductor package is mounted). And an annular first flat surface portion extending to the back surface of the substrate following the other end of the cylindrical portion. The hole conductor provided in this substrate is typically composed mainly of a metal material, and a material with high thermal conductivity is suitable as the metal material, for example, copper, silver, gold, platinum Pure metals such as nickel, cobalt and zinc, and alloys containing them are preferably used. As described above, the hole conductor having high thermal conductivity extends to the back surface side of the substrate, so that an effect of releasing heat generated from the semiconductor package to the back surface side of the substrate can be obtained.

  In the above configuration, by optimizing the position of the through hole, the heat trapped between the semiconductor package and the substrate is dissipated to the back side of the substrate through the through hole and the conductor when the semiconductor device is used. Therefore, the warpage between the substrate and the semiconductor package can be reduced, and the bonding failure of the solder layer can be suppressed. In addition, by providing a through hole, the hollow portion of the through hole can absorb the thermal expansion of the substrate due to the heat generated from the semiconductor element, so that the amount of deformation is relatively suppressed compared to the case without the through hole. The effect that it can be done can also be produced.

  However, compared to glass-epoxy substrates and hole conductors, air present in hollow conductors has a relatively low thermal conductivity, which can be a factor in reducing heat dissipation. For example, the thermal conductivity of the epoxy resin used for the substrate is 0.21 W / mK, whereas the thermal conductivity of copper cited as an example of the hole conductor in the cited document 1 is 398 W / mK, The thermal conductivity of air is about 0.024 W / mK, and the thermal conductivity of air is extremely low.

  In addition, taking advantage of the fluidity of air, for example, it is possible to consider a measure to convect air by acting from the outside of the semiconductor device and forcibly remove heat trapped between the semiconductor package and the substrate. The part where the heat is trapped is in the shape of an air pocket, and even if you try to exhaust heat forcibly by external action, the exhaust heat is incomplete due to insufficient air convection. .

  For further examination, it is more effective to reduce the difference in expansion between the upper and lower surfaces of the substrate and to reduce the difference in expansion between the upper and lower surfaces of the substrate, compared to the structure in which heat is released from the back surface of the substrate. Bonding failure due to peeling or cracking is suppressed.

  The present invention has been made in view of the above-described problems, and by performing simple processing on a substrate of a semiconductor device, at least generation of warpage of the substrate due to heat generation during use of the semiconductor device is suppressed or reduced. It is an object of the present invention to provide a semiconductor device capable of effectively suppressing fatigue failure of a solder layer for joining a semiconductor package.

  In order to solve the above-mentioned problems, the present inventors have closed the through-hole formed in the substrate on which the semiconductor package is mounted with a heat conductive material having relatively higher thermal conductivity than the substrate. Thus, it has been found that the warpage of the substrate due to the thermal expansion of the upper and lower surfaces of the substrate caused by the heat generated when the semiconductor device is used is effectively suppressed, and the semiconductor device of the present invention has been achieved.

  That is, the semiconductor device of the present invention seals at least the semiconductor element so that the heat dissipating pad, the semiconductor element fixed to one surface of the heat dissipating pad, and the other surface of the heat dissipating pad are exposed. In a semiconductor device comprising: a semiconductor package comprising: a sealing resin body; a substrate on which the semiconductor package is mounted; and a solder layer that joins the other surface of the heat dissipating pad to the substrate. In addition, a through hole extending from one surface facing the semiconductor package to the other surface is formed at least at a position corresponding to the heat dissipating pad, and the through hole is relatively thermally conductive as compared to the substrate. It is characterized by being blocked by a heat conductive material having a high rate.

  An object of the semiconductor device of the present invention is to equalize the temperature on the upper and lower surfaces of the substrate, reduce the difference in thermal expansion between the upper and lower surfaces, and suppress the warpage of the substrate. For this purpose, it is necessary to efficiently transfer heat accumulated between the semiconductor package and the substrate to the back surface of the substrate.

  Therefore, the semiconductor device according to the present invention applies a configuration in which a through-hole opened at least at a position corresponding to a heat radiating pad is closed with a heat conductor having a relatively high thermal conductivity compared to the substrate. This configuration makes it possible to transfer heat trapped between the semiconductor package and the substrate when the semiconductor device is used to the back surface of the substrate more efficiently than the substrate, and to reduce the temperature on the top and bottom surfaces of the substrate. It is possible to make uniform in time.

  Here, the number of bases of both the through hole and the heat conducting material that closes the through hole is not limited as long as a desired heat transfer effect is obtained. The same applies to the size.

  Further, as a further modification of the structure described above, a hollow member having a relatively high thermal conductivity as compared with the substrate is disposed inside the through hole, and the heat conductive material is blocked by the hollow member. It may be a structure.

  Here, it is preferable that the heat conductive material is a material in which the solder after forming the solder layer flows into the through hole and is hardened. Since the formation of the heat conductive material can be performed simultaneously with the formation of the solder layer on the substrate, it is possible to save the trouble of separately manufacturing the heat conductive material and disposing it in the through hole or the hollow member, thereby improving the manufacturing efficiency.

  In that case, the main component of the solder flowing into the through hole is generally tin, and its thermal conductivity is about 65 W / mK. Therefore, a hollow member made of copper or the like having a higher thermal conductivity than tin is used. By adding, heat can be more efficiently transferred to the back surface of the substrate, and the temperature of the upper and lower surfaces of the substrate can be made uniform in a shorter time. Further, in general, the hollow member formed separately is less in surface roughness than the through-hole formed in the substrate, that is, the surface has good fluid fluidity, so that the hollow member Solder is allowed to flow inside and hardened, so that the high fluidity of the solder and the manufacturing time resulting therefrom can be shortened.

  Furthermore, a heat sink is disposed on the other surface of the substrate, and the heat sink is directly or indirectly connected to the heat conductor that closes the through hole. By adopting a structure having a relatively large external dimension compared to the pad, the temperature of the back surface of the substrate can be made uniform efficiently over a wide range of the substrate.

  As another embodiment of the semiconductor device of the present invention, an electrode that communicates with the semiconductor element via a conductive wire is disposed at a position away from the semiconductor element in the sealing resin body. In the semiconductor device in which the semiconductor package is bonded to the substrate via a separate solder layer on the exposed surface of the electrode, the semiconductor package is blocked by the thermal conductor. A separate through hole is disposed at a position corresponding to the electrode of the substrate, and the thermal conductor communicates with the semiconductor element via the separate solder layer, the electrode, and the conductive wire. It may be what you are doing.

  According to this embodiment, the heat generated from the semiconductor element is transferred to a separate heat conducting material located at a position away from the semiconductor element on the substrate via the conducting wire, in addition to the heat conducting material directly under the semiconductor element. Therefore, the effect of heat transfer to the back surface of the substrate is further enhanced, and the temperature of the top and bottom surfaces of the substrate can be made more uniform over a wider area.

  Note that the term “broad area” as used herein means that the entire surface of both the upper and lower surfaces of the substrate, as well as the substantially entire surface of both.

  In the substrate, a separate heat sink is disposed on the other surface, and the separate heat sink is connected to the thermal conductor that closes the separate through hole, and the separate heat sink is provided in a plan view. By having an external dimension that is relatively larger than the external dimension of the through-hole, it is possible to further ensure the uniform temperature over the wide area of the upper and lower surfaces of the substrate.

  According to the semiconductor device of the present invention, the through hole formed in the substrate on which the semiconductor package is mounted is closed by the heat conductive material having relatively higher thermal conductivity than the substrate. Warpage generated in the substrate due to the difference in thermal expansion between the upper and lower surfaces can be effectively suppressed. As a result, fatigue failure of the solder layer joining the substrate and the semiconductor package can be suppressed, solder joint failure can be improved, and at the same time, peeling of the wiring pattern on the substrate can be prevented. Furthermore, the temperature reached by the semiconductor element at a high temperature can be lowered, which leads to an increase in the life of the semiconductor element (that is, the maximum number of times the semiconductor is used).

1 is a longitudinal sectional view of a first embodiment of a semiconductor device of the present invention. It is an II-II arrow line view of FIG. FIG. 3 is a view taken along the line III-III in FIG. 1, and is a plan view specifically illustrating an embodiment of a through hole provided in a substrate. It is a longitudinal cross-sectional view of 2nd Embodiment of the semiconductor device of this invention. It is a longitudinal cross-sectional view of 3rd Embodiment of the semiconductor device of this invention. It is a longitudinal cross-sectional view of 4th Embodiment of the semiconductor device of this invention. It is a VII-VII arrow line view of Drawing 6, and is a top view explaining other embodiments of a heat sink especially. It is a longitudinal cross-sectional view of the conventional semiconductor device. It is the IX-IX arrow line view of FIG.

  Hereinafter, embodiments of a semiconductor device of the present invention will be described with reference to the drawings. In addition, all of the semiconductor element, the heat dissipation pad, the sealing resin body, and the substrate shown in the figure have a square shape in plan view, but the shape in plan view may be rectangular, circular, elliptical, or the like. Further, any combination thereof may be used. Further, in the illustrated example, the inner electrode and the outermost electrode indicate a two-row electrode arrangement form, but are not limited to the illustrated example such as an electrode arrangement form of one row or three or more rows.

  FIG. 1 is a longitudinal sectional view of a first embodiment of a semiconductor device according to the present invention, FIG. 2 is an arrangement position of semiconductor elements and electrodes of a semiconductor package in the first embodiment, and FIG. It is the figure explaining one Embodiment of the through-hole provided in the board | substrate of an apparatus. 4 to 6 are longitudinal sectional views of other embodiments of the semiconductor device of the present invention, and FIG. 7 is a diagram illustrating another embodiment of the heat sink provided on the back surface of the substrate.

  A semiconductor device 100 of the present invention shown in FIG. 1 is obtained by bonding a semiconductor package 10 and a substrate 8 via solder layers 93, 94, 95.

  First, the configuration of the semiconductor package 10 will be described. The semiconductor element 1 is bonded to the upper surface of the heat dissipating pad 3 (die pad) by a die bonding material 2 such as a conductive adhesive made of Ag paste, and an inner electrode 4 and an outermost electrode 5 are disposed outside the heat dissipating pad 3. The semiconductor element 1 is electrically connected to the inner electrode 4 and the outermost electrode 5 by a conductive wire 6. In this state, the semiconductor element 1, etc. are loaded in the transfer mold, and the semiconductor element 1, the heat dissipating pad 3, the electrodes 4, 5 and so on are exposed so that a part of each of the heat dissipating pad 3 and the electrodes 4, 5 is exposed. The conducting wire 6 is integrally sealed by a sealing resin body 7 using a semiconductor sealing epoxy, and a semiconductor package 10 is formed.

  Here, the size and material of the heat dissipating pad 3 are not particularly limited as long as the heat dissipating pad 3 has heat dissipating performance and can be mounted with a semiconductor element. However, from the viewpoint of stability and heat dissipation, it is preferable that the heat dissipation pad is larger than the semiconductor, and materials with high thermal conductivity are suitable, for example, copper, silver, gold, platinum, nickel Pure metals such as cobalt and zinc, and alloys containing them are preferably used. Further, the exposed surfaces of the heat dissipating pad 3 and the electrodes 4 and 5 may be plated with a metal (nickel, chromium, gold, etc.) having good solder leakage.

  Next, the substrate 8 will be described. In a process separate from the process of forming the semiconductor package 10, a through hole 81 is previously opened in the substrate 8 on which the semiconductor package 10 is mounted by drilling.

  For example, as the substrate 8, various substrates such as a glass substrate, a glass-epoxy substrate, an alumina substrate, and a zirconia substrate can be used. Generally, the substrate 8 has a higher thermal conductivity than air and is higher than a metal such as copper. Also, a material with low thermal conductivity is used. Furthermore, the substrate may be either a single layer or a laminated structure. Also, as a through hole processing method, in addition to the above drill processing, it can be opened by a method such as punching or laser processing such as excimer laser or carbon dioxide laser. The method of providing may be sufficient.

  After the pre-process of forming the semiconductor package 10 and the substrate 8 described above, the semiconductor package 10 is disposed on the mounting surface 8a of the substrate 8 to which a solder paste (including ball solder or the like) is applied. Next, these are placed in a reflow furnace and the solder is reflowed, whereby the exposed portions of the heat dissipating pads 3 and the electrodes 4 and 5 constituting the semiconductor package 10 and the substrate 8 are solder layers 93, 94, 95 is joined. Here, a part of the solder melted at the time of reflow flows into the through-hole 81 disposed immediately below the solder layer 93, and the through-hole 81 is closed by the solder 82 formed by curing.

  Further, the back surface 8b of the substrate 8 is connected to the solder 82 blocking the through hole 81, and the heat sink 11 having a relatively large external dimension as compared with the heat dissipating pad 3 in plan view. By being disposed, the semiconductor device 100 is formed.

  Here, as a material for forming the heat sink 11, it is generally preferable to use a metal having excellent thermal conductivity. After the through hole 81 is closed with the solder 82, the heat sink 11 is disposed on the back surface 8 b of the substrate 8 by welding or adhesion. It may be provided, or may be provided in advance on the back surface 8b of the substrate 8 when the substrate 8 is formed by using a wiring pattern in combination.

  Further, the through hole 81 is blocked by the solder that flows in during reflow, but in addition to this, the through hole 81 is blocked in advance by a material having a high thermal conductivity such as that used for a heat dissipating pad when forming the substrate in the pre-reflow process. You may keep it. More specifically, after the through hole is opened in the substrate by machining or laser processing, the through hole is closed with a material having high thermal conductivity such as copper.

  One embodiment of the through hole 81 corresponding to the positions of the semiconductor element 1, the heat dissipating pad 3 and the electrodes 4, 5 shown in FIG. 2 is shown in FIG. 3, and corresponds to each side of the heat dissipating pad 3. One circular through hole 81 is provided at each position. In addition to the arrangement of the through holes shown in FIG. 3, the number of bases is not limited as long as a desired heat transfer effect is obtained, and the arrangement position of the through holes is, for example, on the diagonal line of the heat dissipation pad. It may be arranged at a position corresponding to the above, or the arrangement position may not be symmetric, for example, by being intensively arranged at a position where the heat radiation of the semiconductor element is large. Of course, it goes without saying that the cross-sectional shape and size of the through holes are the same.

  Next, an aspect of heat transfer from the semiconductor element 1 that is a heat source when the semiconductor device 100 is used will be described.

  The thermal conductivity of tin, which is the main component of the solder 82 that closes the through-hole 81 in FIG. 1, is about 65 W / mK, compared to the thermal conductivity of 0.21 W / mK of the epoxy resin often used for the substrate 8. Since the heat conductivity is good, the heat that is about to be trapped between the semiconductor package 10 and the substrate 8 when the semiconductor device is used is mainly transferred to the back surface 8b side of the substrate 8 through the solder 82.

  First, at the start of semiconductor use, the temperature of the semiconductor element 1 rises. The heat generated from the semiconductor element 1 is transferred to the heat dissipating pad 3 directly below through the die bonding material 2, the temperature of the heat dissipating pad 3 rises, and then the temperature of the solder layer 93 rises. As the temperature of the solder layer 93 rises, the temperature of each of the solder 82 and the substrate 8 in contact with the solder layer 93 also rises. However, as compared with the case where heat is transferred only by the substrate 8, the solder 82 has a higher thermal conductivity. Thus, heat is transferred to the back surface 8b of the substrate 8 in a shorter time (arrow A). Heat transfer is continued until the temperature of the solder layer 93 and the temperature of the heat sink 11 become constant. In the form in which the heat sink 11 has a relatively large external dimension as compared to the heat dissipating pad 3 in plan view as in the illustrated example, the heat sink performance is further enhanced, The temperature difference can be eliminated in a shorter time.

  Here, the solder 82 that closes the through hole 81 in the first embodiment is one in which the solder after forming the solder layer 93 flows and hardens during reflow, but the method of closing the through hole 81 with solder is used. As a method, solder may be supplied from the back surface 8b of the substrate 8 by a solder supply device (not shown) during reflow. In this method, the solder supplied to the through hole 81 from the back surface 8b of the substrate 8 at the time of reflow rises naturally toward the mounting surface 8a of the substrate 8 by capillary action, and closes the through hole 81. In order to promote this capillary action, a deaeration hole (not shown) that allows the through-hole 81 to communicate with each other is preferably arranged at an appropriate position.

  FIG. 4 is a longitudinal cross-sectional view of the second embodiment of the semiconductor device of the present invention, and a detailed description of the same components as those in FIG. 1 is omitted.

  In FIG. 4, a hollow member 83 having a relatively high thermal conductivity as compared with the substrate 8A is disposed inside the through hole 81 disposed in the substrate 8A. This is the same as the embodiment. At the time of reflow, the solder after forming the solder layer 93 flows into the hollow member 83 provided in the through hole 81 disposed immediately below the solder layer 93, and the hollow member 83 is blocked by the solder 84 formed by curing the solder. The

  Further, the hollow member 83 is closed by the solder that flows in at the time of reflow. However, in the same way as in the first embodiment, when the substrate is formed in the pre-reflow process, the hollow member 83 is previously made of a material having high thermal conductivity that is used for the heat dissipation pad. It may be occluded. Furthermore, solder may be supplied to the hollow member 83 from the back surface 8Ab of the substrate 8A during reflow.

  According to the second embodiment, by using a pure metal or alloy such as copper having higher thermal conductivity than the solder 84 for the hollow member 83, heat conduction from the mounting surface 8Aa to the back surface 8Ab is further promoted. can do. In general, compared to the through-hole 81 provided in the substrate 8A, the surface roughness of the hollow member 83 formed separately is small, that is, the fluid fluidity of the surface is good. The flowability of the solder flowing into the hollow member 83 during reflow is also improved, and the time required for closing the hollow member 83 can be reduced. This also means shortening the heating time of the semiconductor device 100A itself, which leads to suppressing damage to the semiconductor device 100A due to thermal shock. The same applies to the case where the solder is supplied from the back surface 8Ab of the substrate 8A with the solder supply device and the hollow member 83 is closed.

  FIG. 5 is a longitudinal sectional view of a third embodiment of the semiconductor device of the present invention, which is a modification of the configuration of the hollow member and the heat sink with respect to FIG.

  In FIG. 5, the hollow member 85 and the solder 86 that closes the hollow member 85 are set to protrude from the back surface 8Bb of the substrate 8B by the thickness of the heat sink 12. The heat sink 12 is provided with an opening having the same dimension as the external dimension of the hollow member 85 in a plan view at a position corresponding to the hollow member 85, and is in contact with the hollow member 85 inside the opening of the heat sink 12.

  According to the third embodiment, it can be installed by fitting the heat sink 12 to the hollow member 85, and steps such as welding and adhesion can be eliminated. Further, in the first and second embodiments, from the viewpoint of deaeration in the through hole, it is preferable that the heat sink is installed after the through hole is closed by solder. If used, a through hole can be opened in a substrate on which an existing wiring pattern is set, and a function as a heat sink can be added to the wiring pattern. Therefore, the existing manufacturing process only needs to be improved slightly.

  Furthermore, the heat sink 12 and the hollow member 85 of the third embodiment may be integrally formed. By integrating the heat sink 12 and the hollow member 85, when the hollow member 85 is fitted into the through hole 81, the heat sink 12 can be simultaneously installed on the substrate 8B.

  FIG. 6 is a longitudinal sectional view of a semiconductor device according to a fourth embodiment of the present invention. The configuration of the through hole at a position corresponding to the heat dissipating pad 3 in the fourth embodiment is the first embodiment. However, it goes without saying that the same effect can be obtained even if the second and third embodiments are used.

  In the fourth embodiment, the substrate 8C before the semiconductor package 10 is mounted penetrates to the position corresponding to the electrodes 4 and 5 separately from the through hole 81 corresponding to the heat dissipation pad 3. Holes 87 and 89 are opened.

  Similar to the above-described embodiment, a part of the solder melted at the time of reflow flows into the through holes 87 and 89 disposed immediately below the solder layers 94 and 95, and is cured by the solders 88 and 90 formed by curing. The through holes 87 and 89 are closed.

Further, the back surface 8Cb of the substrate 8C is connected to the solders 88 and 90 closing the through holes 87 and 89, and has a relatively large external dimension as compared to the through holes 87 and 89 in a plan view. By disposing the heat sinks 13 and 14, the semiconductor device 100C is formed.
Here, the through holes 87 and 89 are closed by the solder that flows in at the time of reflow. However, the through holes 87 and 89 may be previously closed by a material having high thermal conductivity such as copper when the substrate is formed. For example, a copper via generally used for reinforcing the rigidity of a substrate may be used in combination with the above-described function as a heat conductive material.

  Next, a mode of heat transfer from the semiconductor element 1 as a heat generation source through the electrode portions 4 and 5 when the semiconductor device 100C is used will be described.

  First, at the start of semiconductor use, the temperature of the semiconductor element 1 rises. The heat generated from the semiconductor element 1 is mainly transferred to the heat dissipating pad 3 directly below the bonding material 2, but part of the heat is transferred to the electrodes 4 and 5 via the conductor 6 (arrow C), Next, the temperature of the solder layers 94 and 95 rises. The temperature of the solder layers 94 and 95 raises the temperature of each of the solder 88 and 90 and the substrate 8C in contact with the solder layers 94 and 95, but the thermal conductivity is higher than that in the case where heat is transferred only by the substrate 8C. Heat is transferred to the back surface 8Cb of the substrate 8C in a shorter time by passing through the high solders 88 and 90 (arrow D). Heat transfer is continued until the temperature of the solder layers 94 and 95 and the temperature of the heat sinks 13 and 14 become constant, and the temperature of the solder layers 93, 94 and 95 and the temperature of the heat sinks 11, 13 and 14 in the entire substrate 8C. Heat transfer is continued until becomes constant. In the form in which the heat sinks 13 and 14 have relatively large external dimensions as compared to the through holes 87 and 89 in plan view as in the illustrated example, the heat sink performance is further enhanced, and the upper surface of the substrate 8C is increased. The temperature difference on the lower surface can be eliminated in a shorter time.

  6 illustrates the flow of heat through the electrode portion provided on the left side of the semiconductor device center in the vertical cross-sectional view of the semiconductor device 100C, the same applies to the electrode portion provided on the right side of the semiconductor device center. Needless to say, a heat flow is generated.

  FIG. 7 is a view of the substrate 8C of the semiconductor device 100C of the embodiment of FIG. 6 as viewed from the back side. The heat sink 11 and the heat sinks 13 and 14 are disposed at positions where they do not contact each other. In the fourth embodiment, the heat sink 11 and the heat sinks 13 and 14 have a square shape in a plan view, but the shape is not limited to a rectangle, a circle, an ellipse, or a combination thereof. . Also, the size of each heat sink can be changed as appropriate, for example, by increasing the size of the heat sink connected to the portion of the semiconductor element 1 where heat dissipation is large. Furthermore, it is needless to say that it is not necessary to dispose a heat sink on all electrode portions as in the fourth embodiment, and it is not necessary to align the center of the heat sink with the center of the through hole.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor element, 3 ... Heat dissipation pad, 4 ... Inner electrode, 5 ... Outermost electrode, 7 ... Sealing resin body, 8, 8A, 8B, 8C ... Substrate, 10 ... Semiconductor package, 11, 12, DESCRIPTION OF SYMBOLS 13,14 ... Heat sink, 81, 87, 89 ... Through-hole, 83, 85 ... Hollow member, 93, 94, 95 ... Solder layer, 100, 100A, 100B, 100C ... Semiconductor device

Claims (6)

A heat dissipating pad; a semiconductor element fixed to one surface of the heat dissipating pad; and a sealing resin body for sealing at least the semiconductor element so as to expose the other surface of the heat dissipating pad. In a semiconductor device comprising: a semiconductor package to be mounted; a substrate on which the semiconductor package is mounted; and a solder layer that bonds the other surface of the heat dissipating pad to the substrate.
A through hole extending from one surface facing the semiconductor package to the other surface is opened at least in a position corresponding to the heat dissipating pad in the substrate.
The semiconductor device, wherein the through hole is closed with a heat conductive material having a relatively high thermal conductivity as compared with the substrate.   2. The semiconductor device according to claim 1, wherein a hollow member having a relatively high thermal conductivity as compared with the substrate is disposed inside the through hole, and the heat conductive material closes the hollow member. .   3. The semiconductor device according to claim 1, wherein the heat conductive material is made of a material in which the solder after forming the solder layer flows into the through hole and is hardened. 4.   In the substrate, a heat sink is disposed on the other surface, and the heat sink is directly or indirectly connected to the heat conductor closing the through hole, and the heat dissipating pad in plan view. The semiconductor device according to claim 1, wherein the semiconductor device has a relatively large external dimension as compared with the semiconductor device. An electrode communicating with the semiconductor element via a conductor is embedded in the sealing resin body at a position away from the semiconductor element so that a part of the electrode is exposed to the substrate side. However, in the exposed surface of the electrode, in the semiconductor device joined to the substrate through a separate solder layer,
A separate through hole closed with the heat conductor is disposed at a position corresponding to the electrode of the substrate,
5. The semiconductor device according to claim 1, wherein the thermal conductor is in communication with the semiconductor element through the separate solder layer, the electrode, and the conductive wire. In the substrate, a separate heat sink is disposed on the other surface, and the separate heat sink is connected to the thermal conductor closing the separate through hole, and the separate through hole is seen in a plan view. The semiconductor device according to claim 5, wherein the semiconductor device has an external dimension relatively larger than an external dimension of the hole.

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