semiconductor devices

Abstract

The object is to provide a semiconductor device having excellent heat dissipation and electromagnetic wave suppression effects. In order to solve the above-mentioned problems, the semiconductor device (1) of the present invention comprises: a semiconductor element (30) formed on a substrate (50); a conductive shielding cover (20) having an opening (21); a conductive cooling member (40) provided on the upper portion of the conductive shielding cover (20); a heat conducting sheet (10) formed between the semiconductor element (30) and the conductive cooling member (40) at least through the opening (21); and a conductive member (11) electrically connecting the conductive shielding cover (20) and the conductive cooling member (40).

Description

Technical Field

[0001] The present invention relates to a semiconductor device having excellent heat dissipation and electromagnetic wave suppression effects. Background Art

[0002] In recent years, electronic devices have been miniaturized. However, due to the diversity of applications, power consumption cannot be greatly varied. Therefore, more emphasis is placed on heat dissipation measures within the devices.

[0003] As heat dissipation countermeasures in these electronic devices, heat sinks, heat pipes, or fins made of metal materials with high thermal conductivity, such as copper and / or aluminum, are widely used. To achieve heat dissipation and reduce temperature within the device, these highly thermally conductive heat dissipating components are positioned close to electronic components, such as semiconductor packages, that serve as heat sources within the electronic device. Furthermore, these highly thermally conductive heat dissipating components are positioned close to the heat-generating electronic components at a lower temperature.

[0004] However, the heat-generating components within electronic devices are electronic components such as semiconductor elements, which have high current densities. High current densities are considered to represent high electric and magnetic field intensities, potentially contributing to unwanted radiation. Therefore, placing a metal heat dissipation component near an electronic component can absorb heat while also picking up the higher harmonic components of the electrical signals flowing within the component. Specifically, because the heat dissipation component is made of metal, it can act as an antenna for the higher harmonic components or as a transmission path for higher harmonic noise components.

[0005] Therefore, the development of a technology that achieves both heat dissipation and electromagnetic wave suppression effects is desired.

[0006] For example, Patent Document 1 discloses a technology in which a semiconductor package with a lid attached is placed in a shield member having a large opening, an annular lid contact portion is provided that electrically contacts the upper peripheral edge of the lid, and the lid contact portion is electrically connected to the shield member.

[0007] However, although the technology of Patent Document 1 can achieve certain heat dissipation and electromagnetic wave suppression effects, it is believed that when the substrate and cooling member are large, electromagnetic resonance will occur, and sufficient electromagnetic wave suppression effects cannot be achieved. In addition, further improvement in heat dissipation is also desired.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-1654852 Summary of the Invention

[0011] Technical issues

[0012] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor device having excellent heat dissipation and electromagnetic wave suppression effects.

[0013] Technical Solution

[0014] The inventors conducted repeated research to address the aforementioned issues and focused on the possibility of achieving superior electromagnetic wave absorption performance by providing a conductive shield connected to a ground line in a manner that covers the semiconductor element. However, since sufficient heat dissipation cannot be achieved simply by providing a conductive shield, further in-depth research led to the discovery that by providing an opening in the conductive shield and forming a heat conducting sheet at least through the opening to connect the semiconductor element to a conductive cooling member, heat dissipation can be improved without degrading electromagnetic wave absorption performance. Furthermore, the inventors discovered that by further providing a conductive member between the upper surface of the conductive shield and the lower surface of the conductive cooling member, and electrically connecting the conductive shield and the conductive cooling member, the electromagnetic wave suppression effect can be enhanced even when the conductive shield has an opening.

[0015] As a result, the semiconductor device of the present invention can achieve both heat dissipation and electromagnetic wave suppression effects at an unprecedentedly high level.

[0016] The present invention has been completed based on the above findings, and the gist of the present invention is as follows.

[0017] (1) A semiconductor device, characterized in that it comprises: a semiconductor element formed on a substrate; a conductive shielding cover connected to a ground line and having an opening; a conductive cooling member arranged on an upper portion of the conductive shielding cover; a heat conducting sheet formed between the semiconductor element and the conductive cooling member at least through the opening of the conductive shielding cover; and a conductive member formed between an upper surface of the conductive shielding cover and a lower surface of the conductive cooling member to electrically connect the conductive shielding cover and the conductive cooling member.

[0018] With the above configuration, it is possible to achieve excellent heat dissipation and electromagnetic wave suppression effects.

[0019] (2) The semiconductor device described in (1) above is characterized in that a distance between the conductive members facing each other with the thermally conductive sheet interposed therebetween is 1 / 10 or less of a wavelength at a maximum frequency of the semiconductor element.

[0020] (3) The semiconductor device described in (2) above is characterized in that the conductive member is connected to the conductive shield and the conductive cooling member to form an electrically closed region.

[0021] (4) The semiconductor device according to any one of (1) to (3) above, wherein the electrical resistance of the conductive member is 2Ω or less.

[0022] (5) The semiconductor device according to any one of (1) to (4) above, wherein the conductive member has adhesiveness or adhesion on its surface.

[0023] (6) The semiconductor device according to any one of (1) to (5) above, wherein the conductive member includes a cured resin.

[0024] (7) The semiconductor device according to any one of (1) to (6) above, wherein the conductive member contains a conductive filler.

[0025] (8) The semiconductor device according to any one of (1) to (7) above, wherein the thermally conductive sheet includes carbon fibers.

[0026] Technical Effects

[0027] According to the present invention, a semiconductor device having excellent heat dissipation and electromagnetic wave suppression effects can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a diagram schematically showing a cross-sectional view of one embodiment of a semiconductor device according to the present invention.

[0029] Figure 2 This is a diagram schematically showing a cross-sectional view of another embodiment of the semiconductor device of the present invention.

[0030] Figure 3 This is a diagram schematically showing a cross-sectional view of another embodiment of the semiconductor device of the present invention.

[0031] Figure 4 This is a perspective view schematically showing an assembled state of one embodiment of the semiconductor device of the present invention.

[0032] Figure 5 is a diagram schematically showing a model of a semiconductor device used for frequency characteristic analysis in an embodiment, Figure 5 (a) shows a state observed from the surface side of the model of the semiconductor device, Figure 5 (b) shows a state observed from the back side of the semiconductor device model.

[0033] Figure 6 This is a diagram schematically showing a cross-sectional state of a conventional semiconductor device.

[0034] Figure 7This is a graph showing the electric field intensity versus frequency for each sample having different resistance values ​​of the conductive member of the semiconductor device in Example 1.

[0035] Explanation of symbols

[0036] 1: Semiconductor devices

[0037] 10: Thermal conductive sheet

[0038] 11: Conductive components

[0039] 20: Conductive shield

[0040] 20a: Upper surface of the conductive shield

[0041] 20b: Bottom surface of the conductive shield

[0042] 21: Opening

[0043] 30: Semiconductor components

[0044] 31: MSL

[0045] 40: Conductive cooling component

[0046] 40b: Lower surface of the conductive cooling member

[0047] 50: Substrate

[0048] 51: Joint

[0049] 52: Conductive treatment through hole

[0050] 60: Ground

[0051] 100: Existing semiconductor devices

[0052] A: Electrically enclosed space

[0053] T: thickness of thermal pad

[0054] P: The distance between the conductive members facing each other through the thermal conductive sheet DETAILED DESCRIPTION

[0055] Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

[0056] here, Figures 1 to 3 1 is a diagram schematically showing a cross section of an embodiment of a semiconductor device of the present invention. Figure 4This is a perspective view illustrating an assembled state of one embodiment of a semiconductor device according to the present invention. It should be noted that, for ease of explanation, the shapes and / or proportions of various components in each drawing differ from actual shapes and / or proportions. The shapes and / or proportions of various components, other than those specified in this specification, may be appropriately modified for each semiconductor device.

[0057] like Figures 1 to 3 As shown, the semiconductor device 1 of the present invention includes a semiconductor element 30 , a conductive shield 20 , a conductive cooling member 40 , a thermally conductive sheet 10 , and a conductive member 11 .

[0058] Furthermore, in the semiconductor device 1 of the present invention, it is characterized in that: the conductive shielding cover 20 has an opening portion 21, the heat conductive sheet 10 is formed between the semiconductor element 30 and the conductive cooling component 40 in a manner passing through the opening portion 21; and the conductive component 11 is formed between the upper surface 20a of the conductive shielding cover 20 and the lower surface 40b of the conductive cooling component, electrically connecting the conductive shielding cover 20 and the conductive cooling component 40.

[0059] The semiconductor element 30 generates heat and electromagnetic waves, but the conductive shield 20 is provided to cover the semiconductor element 30, thereby shielding the electromagnetic waves and achieving excellent electromagnetic wave suppression. Furthermore, by providing an opening 21 in the conductive shield 20 and positioning a sheet member (thermal conductive sheet 10) with electromagnetic wave absorption and high thermal conductivity between the semiconductor element 30 and the conductive cooling member 40, passing at least through the opening 21, heat conduction to the conductive cooling member 40 is significantly improved, resulting in excellent heat dissipation.

[0060] In addition, the conductive shielding cover 20 is electrically connected to the conductive cooling component 40 through the conductive component 11, thereby forming an electrically closed space in the semiconductor device 1 of the present invention. As a result, the electromagnetic wave blocking effect of the conductive shielding cover 20 can be improved, and even when the conductive shielding cover 20 is provided with an opening portion 21, a high electromagnetic wave suppression effect can be obtained.

[0061] It should be explained that Figure 6 This figure shows an example of a conventional semiconductor device equipped with a thermally conductive sheet. In conventional semiconductor device 100, a thermally conductive sheet 10 is provided between semiconductor element 30 and conductive cooling member 40, thereby achieving excellent thermal conductivity. However, since it lacks an electromagnetic shielding member such as shield cover 20 and / or a member to enhance the electromagnetic shielding effect such as conductive member 11, as in the semiconductor device 1 of the present invention, it does not achieve a sufficient level of electromagnetic wave suppression.

[0062] Next, each member constituting the semiconductor device of the present invention will be described.

[0063] (Semiconductor components)

[0064] like Figures 1 to 3 As shown in FIG. 1 , the semiconductor device 1 of the present invention includes a semiconductor element 30 formed on a substrate 50 .

[0065] Here, the semiconductor element 30 is not particularly limited as long as it is an electronic component formed of a semiconductor, and examples thereof include integrated circuits such as ICs and LSIs, CPUs, MPUs, graphic processing elements, and image sensors.

[0066] There is no particular limitation on the substrate 50 on which the semiconductor element 30 is formed, and a suitable substrate can be used according to the type of semiconductor device. A ground line (GND) 60 is provided on the substrate 50. The ground line 60 is formed on the inner layer or the back surface (on the inner layer) of the substrate 50. Figures 1 to 3 The back side of the substrate is shown in the middle).

[0067] Furthermore, in the semiconductor device 1 of the present invention, for example, Figures 1 to 3 As shown, a joint portion 51 can be provided on the surface of the substrate 50 in a manner that surrounds the semiconductor element 30, all around or partially, and the conductive shield 20 can be connected to this portion by solder or the like. The joint portion 51 is electrically connected to the ground line 60 through a conductive through-hole 52 formed in the substrate 50, thereby electrically connecting the conductive shield 20 to the ground line 60. It should be noted that Figures 1 to 3 In the embodiment, the conductive shield 20 is provided on the joint portion 51 to be electrically connected to the ground line 60 . However, the conductive shield 20 may also pass through the interior of the substrate 50 and be directly connected to the ground line 60 .

[0068] (Shielding cover)

[0069] like Figures 1 to 3 As shown, the semiconductor device 1 of the present invention includes a conductive shield 20 connected to a ground line 60 and having an opening 21 .

[0070] The conductive shield 20 connected to the ground line 60 can shield electromagnetic waves, thereby improving the electromagnetic wave suppression effect of the semiconductor device 1 of the present invention.

[0071] Here, the material used to form the shielding cover 20 is a material that has a good electromagnetic wave shielding effect, and there are no particular restrictions. For example, metals with high electrical conductivity such as aluminum, copper, and stainless steel, and / or magnetic materials with high electrical conductivity, can be used. Examples of such magnetic materials with high electrical conductivity include permalloy, sendust alloy, Fe-based or Co-based amorphous materials, microcrystalline materials, and the like. When using such magnetic materials as described above as the material to form the shielding cover 20, in addition to the electrical shielding effect, magnetic shielding effects and magnetic absorption effects can also be expected.

[0072] The opening 21 provided in the shield is a through hole provided in the shield. It should be noted that in order to fill the interior of the opening 21 with the heat conducting sheet 10 described later and connect the semiconductor element 30 and the conductive cooling member 40, as shown in FIG. Figures 1 to 3 As shown, the opening 21 is formed in the direction of connecting the semiconductor element 30 and the conductive cooling member 40 (in the direction of Figures 1 to 3 is the stacking direction of each component).

[0073] The size of the opening 21 is not particularly limited and can be appropriately modified depending on the size of the semiconductor element 30, for example. A smaller opening area of ​​the opening 21 can reduce the emission of electromagnetic waves and the radiated electromagnetic field. However, from the perspective of dissipating heat from the semiconductor element 30, it is preferable to enlarge the opening 21 and use a larger thermally conductive sheet 10. Therefore, the size of the opening 21 can be appropriately modified depending on the thermal conductivity and / or electromagnetic noise suppression required of the semiconductor device 1 of the present invention.

[0074] (Conductive cooling member)

[0075] like Figures 1 to 3 As shown, the semiconductor device 1 of the present invention includes a conductive cooling member 40 on the upper portion of the conductive shield 20 .

[0076] Here, the conductive cooling member 40 absorbs heat generated by the heat source (semiconductor element 30) and releases the heat to the outside. The conductive cooling member 40 is connected to the semiconductor element 30 via the thermal conductive sheet 10 described later, thereby dissipating the heat generated by the semiconductor element 30 to the outside, thereby ensuring the heat dissipation of the semiconductor device.

[0077] Furthermore, the conductive cooling member 40 has electrical conductivity, and thus, is electrically connected to the conductive shield 20 via the conductive member 11 described later, thereby forming an electrically closed space ( Figure 1 The area A) surrounded by the dotted line improves the electromagnetic wave suppression effect of the semiconductor device 1.

[0078] There is no particular limitation on the type of the conductive cooling member 40, and it can be appropriately selected according to the type of the semiconductor device 1 of the present invention. For example, it can include: a heat sink, a cooler, a heat sink, a heat spreader, a chip pad, a cooling fan, a heat pipe, a metal cover, a housing, etc. Among these conductive cooling members, from the perspective of being able to obtain better heat dissipation, it is preferred to use a heat sink, a cooler or a heat sink with conductivity. In addition, from the perspective of improving thermal conductivity, the material constituting the above-mentioned conductive cooling member 40 preferably includes metals such as aluminum, copper, stainless steel and / or graphite.

[0079] Should be explained, such as Figures 1 to 3 As shown, the conductive cooling member 40 is disposed on top of the conductive shield 20, but is preferably disposed at a distance from the conductive shield, rather than in contact with the conductive shield. This allows the heat conducting sheet 10 and / or conductive member 11, described later, to be inserted between the upper surface 20a of the conductive shield 20 and the conductive cooling member 40.

[0080] Furthermore, the conductive cooling member 40 may be provided with a protrusion (not shown) on the portion of its back surface 40b that contacts the conductive member 11 (described later). Providing the protrusion narrows the gap between the conductive cooling member 40 and the conductive member 11 and the conductive shield 20 disposed across the conductive member 11, and enables a secure connection even when the conductive member 11 is formed of a film or the like.

[0081] (Thermal conductive sheet)

[0082] like Figures 1 to 3 As shown, the semiconductor device 1 of the present invention includes a heat conducting sheet 10 formed between the semiconductor element 30 and the conductive cooling member 40 so as to pass through at least the opening 21 of the conductive shield 20 .

[0083] Disposing the highly conductive heat-dissipating sheet 10 between the semiconductor element 30 and the conductive cooling member 40 improves heat dissipation. Furthermore, if the heat-dissipating sheet 10 has electromagnetic wave absorption properties, an electromagnetic wave suppression effect can also be achieved.

[0084] Here, the shape of the thermally conductive sheet 10 is not particularly limited and can be appropriately changed according to the shape of the opening 21 of the conductive shield 20 .

[0085] In addition, there is no particular limitation on the size of the heat conducting sheet 10. Figure 1 As shown, the heat conducting sheet 10 has a cross-sectional area smaller than the area of ​​the opening 21 of the conductive shield 20, and can also be as shown in FIG. Figure 2 or Figure 3As shown, the thermally conductive sheet 10 is sized to cover a portion of the upper surface 20 a of the conductive shield 20 .

[0086] In addition, from the perspective of being able to obtain more excellent heat dissipation and / or electromagnetic wave suppression effect, it is preferred to Figure 3 As shown, the thermal conductive sheet 10 covers a portion of the upper surface 20 a of the conductive shielding cover 20 .

[0087] Furthermore, from the perspective of being able to obtain particularly excellent electromagnetic wave suppression effect, it is preferred that Figure 2 As shown, the thermal conductive sheet 10 covers a portion of the upper surface 20 a and the lower surface 20 b of the conductive shielding cover 20 .

[0088] It should be noted that the thermally conductive sheet 10 may be composed of a single sheet or a plurality of sheets.

[0089] For example, Figure 1 As shown, when the heat conducting sheet 10 does not cover the upper surface 20a or the lower surface 20b of the shield cover 20, the heat conducting sheet 10 can be formed of a single sheet. However, it can also be formed of multiple sheets to facilitate adjustment of the sheet thickness.

[0090] In addition, if Figure 2 and Figure 3 As shown, when the heat conducting sheet 10 covers a portion of the upper surface 20a and / or a portion of the lower surface 20b of the shielding cover 20, the heat conducting sheet 10 can be formed by a single sheet or a plurality of sheets. Figure 2 and Figure 3 By pressing the semiconductor element 30 and the conductive cooling member 40 (in the figure), a portion of the sheet material can be squeezed out to cover a portion of the upper surface 20a and / or a portion of the lower surface 20b of the shield case 20. When the thermally conductive sheet 10 is composed of multiple sheets, a thermally conductive sheet 10 of a desired shape can be obtained by combining sheets of different sizes.

[0091] However, if Figure 2 and Figure 3 As shown, when the thermally conductive sheet 10 covers a portion of the upper surface 20a and / or a portion of the lower surface 20b of the shield case 20, the thermally conductive sheet 10 is preferably formed from a plurality of sheets. Since no steps such as crimping are required, the thermally conductive sheet 10 can be formed with the fibrous thermally conductive filler (described later) oriented, resulting in even better heat dissipation and electromagnetic wave suppression effects.

[0092] It should be noted that in terms of reducing interference during actual installation and / or reducing manufacturing costs, it is preferred to Figure 1 As shown, the cross-sectional area of ​​the thermally conductive sheet 10 is smaller than the area of ​​the opening 21 of the conductive shield 20 (a gap is formed between the thermally conductive sheet 10 and the end of the conductive shield 20 ).

[0093] However, if the gap between the thermally conductive sheet 10 and the end of the conductive shield 20 becomes too large, the heat dissipation effect may be reduced. Therefore, from the perspective of heat dissipation effect, it is preferred that the size X of the gap between the thermally conductive sheet 10 and the end of the conductive shield 20 be set small.

[0094] In addition, there is no particular limitation on the thickness T of the thermally conductive sheet 10 and it can be appropriately changed according to the distance between the semiconductor element 30 and the conductive cooling member 40 and / or the size of the shielding cover 20. However, in order to achieve a higher level of heat dissipation and electromagnetic wave suppression effect, the thickness T of the thermally conductive sheet 10 is preferably 50 μm to 4 mm, more preferably 100 μm to 4 mm, and particularly preferably 200 μm to 3 mm. If the thickness T of the thermally conductive sheet 10 exceeds 4 mm, the distance between the semiconductor element 30 and the conductive cooling member 40 becomes longer, thereby possibly leading to a decrease in thermal conductivity. On the other hand, if the thickness T of the thermally conductive sheet 10 is less than 50 μm, the electromagnetic wave suppression effect may be reduced.

[0095] Here, as Figures 1 to 3 As shown, the thickness T of the thermally conductive sheet 10 refers to the thickness T of the thickest portion of the thermally conductive sheet 10 , including both the case where the thermally conductive sheet 10 is formed by a single sheet and the case where the thermally conductive sheet 10 is formed by multiple sheets.

[0096] Furthermore, the thermally conductive sheet 10 preferably has adhesiveness on its surface. This is because it can improve the adhesion between the thermally conductive sheet 10 and other components. Furthermore, when the thermally conductive sheet 10 is composed of multiple sheets, it can also improve the adhesion between the sheets.

[0097] There is no particular limitation on the method for imparting tack to the surface of the thermally conductive sheet 10. For example, the adhesive resin constituting the thermally conductive sheet 10 (described later) may be optimized to impart tack, or a separate adhesive layer having tack may be provided on the surface of the thermally conductive sheet 10.

[0098] It should be noted that there is no particular limitation on the method for changing the thermal conductivity of the thermally conductive sheet 10. However, as described later, the thermal conductivity can be changed by changing the material, amount, and orientation direction of the fibrous thermally conductive filler in the center and periphery of the sheet.

[0099] Furthermore, the material constituting the thermally conductive sheet 10 is not particularly limited as long as it has excellent electromagnetic wave absorption performance and thermal conductivity.

[0100] For example, from the viewpoint of achieving high levels of electromagnetic wave absorption performance and thermal conductivity, a thermally conductive sheet containing a binder resin and a thermally conductive filler may be used as the thermally conductive sheet.

[0101] The materials constituting the thermally conductive sheet 10 are described below.

[0102] Binder resin

[0103] The binder resin constituting the thermally conductive sheet is a resin component that forms the base material of the thermally conductive sheet. There are no particular limitations on the type of binder resin, and any known binder resin can be selected as appropriate. For example, a thermosetting resin can be used as one example of a binder resin.

[0104] Examples of the thermosetting resin include crosslinkable rubber, epoxy resin, polyimide resin, bismaleimide resin, benzocyclobutene resin, phenolic resin, unsaturated polyester, diallyl phthalate resin, silicone, polyurethane, polyimide silicone, thermosetting polyphenylene ether, and thermosetting modified polyphenylene ether. These may be used alone or in combination of two or more.

[0105] It should be noted that examples of the cross-linkable rubber include natural rubber, butadiene rubber, isoprene rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene propylene rubber, chlorinated polyethylene, chlorosulfonated polyethylene, butyl rubber, halogenated butyl rubber, fluororubber, polyurethane rubber, acrylic rubber, and polyisobutylene rubber. These may be used alone or in combination of two or more.

[0106] In addition, among the above-mentioned thermosetting resins, silicone is preferably used due to its excellent molding processability and weather resistance, and its close adhesion and followability to electronic components. There is no particular limitation on the silicone, and the type of silicone can be appropriately selected according to the purpose.

[0107] From the perspective of achieving the aforementioned moldability, weather resistance, and close adhesion, the silicone is preferably composed of a liquid silicone gel base and a curing agent. Examples of such silicones include addition reaction-type liquid silicones and heat-vulcanized kneading-type silicones that use peroxide for vulcanization.

[0108] As the addition reaction type liquid silicone, a two-component addition reaction type silicone having a polyorganosiloxane having a vinyl group as a main agent and a polyorganosiloxane having a Si—H group as a curing agent is preferably used.

[0109] In the combination of the main agent and the curing agent of the liquid silicone gel, the mixing ratio of the main agent to the curing agent is preferably main agent:curing agent=35:65 to 65:35 in terms of mass ratio.

[0110] Furthermore, the content of the binder resin in the thermally conductive sheet is not particularly limited and can be appropriately selected depending on the intended purpose. For example, from the perspective of ensuring the formability and adhesion of the sheet, the content of the binder resin in the thermally conductive sheet is preferably approximately 20% to 50% by volume of the thermally conductive sheet, and more preferably 30% to 40% by volume of the thermally conductive sheet.

[0111] Thermally conductive fillers

[0112] The thermally conductive sheet contains a thermally conductive filler in the binder resin. The thermally conductive filler is a component for improving the thermal conductivity of the sheet.

[0113] Note that the shape, material, average particle size, etc. of the thermally conductive filler are not particularly limited as long as they can improve the thermal conductivity of the sheet.

[0114] For example, the shape may be spherical, elliptical, massive, granular, flat, needle-like, fibrous, coiled, etc. Among them, a fibrous thermally conductive filler is preferably used because it can achieve higher thermal conductivity.

[0115] The term "fibrous" in the fibrous thermally conductive filler refers to a shape having a high aspect ratio (approximately 6 or greater). Therefore, in the present invention, the fibrous thermally conductive filler includes not only fibrous and / or rod-shaped thermally conductive fillers, but also granular fillers and / or flake-shaped thermally conductive fillers having a high aspect ratio.

[0116] In addition, the material of the fibrous thermally conductive filler is not particularly limited as long as it is a material with high thermal conductivity. For example, aluminum nitride (AlN), silicon dioxide, alumina (aluminum oxide), boron nitride, titanium dioxide, glass, zinc oxide, silicon carbide, silicon (silicon), silicon oxide, aluminum oxide, metal particles, carbon fibers, etc.

[0117] It should be noted that the thermally conductive filler may be used alone or in combination of two or more. Furthermore, when two or more thermally conductive fillers are used, they may all have the same shape or may be mixed together to form a mixture of different shapes.

[0118] Among these fibrous thermally conductive fillers, fibrous metal powder and / or carbon fiber are preferably used, and carbon fiber is more preferably used, from the viewpoint of obtaining higher thermal conductivity.

[0119] There is no particular limitation on the type of carbon fiber and it can be appropriately selected according to the purpose. For example, pitch-based carbon fibers, PAN-based carbon fibers, carbon fibers obtained by graphitizing PBO fibers, carbon fibers synthesized by arc discharge, laser evaporation, CVD (chemical vapor deposition), CCVD (catalytic chemical vapor deposition), etc. can be used. Among them, carbon fibers obtained by graphitizing PBO fibers and pitch-based carbon fibers are more preferred from the perspective of achieving high thermal conductivity.

[0120] Furthermore, if necessary, part or all of the carbon fibers may be surface-treated before use. Examples of such surface treatments include oxidation, nitridation, nitration, and sulfonation, as well as treatments that introduce functional groups onto the surface through these treatments, or that attach or bind metals, metal compounds, or organic compounds to the carbon fibers. Examples of such functional groups include hydroxyl groups, carboxyl groups, carbonyl groups, nitro groups, and amino groups.

[0121] Furthermore, there is no particular restriction on the average fiber length (average major axis length) of the fibrous thermally conductive filler and it can be appropriately selected. However, from the perspective of reliably obtaining high thermal conductivity, it is preferably in the range of 50 μm to 300 μm, more preferably in the range of 75 μm to 275 μm, and particularly preferably in the range of 90 μm to 250 μm.

[0122] Furthermore, the average fiber diameter (average minor axis length) of the fibrous thermally conductive filler is not particularly limited and can be appropriately selected. However, from the perspective of reliably obtaining high thermal conductivity, it is preferably in the range of 4 μm to 20 μm, and more preferably in the range of 5 μm to 14 μm.

[0123] Regarding the aspect ratio (average major axis length / average minor axis length) of the fibrous thermally conductive filler, to ensure high thermal conductivity, a thermally conductive filler with an aspect ratio of 6 or greater is used, preferably 7 to 30. While improvements in thermal conductivity and other properties can be seen with a lower aspect ratio, significant improvements in properties are not achieved due to reduced orientation, so the aspect ratio is set to 6 or greater. On the other hand, an aspect ratio exceeding 30 reduces dispersibility within the thermally conductive sheet, potentially preventing sufficient thermal conductivity.

[0124] Here, the average major axis length and the average minor axis length of the fibrous thermally conductive filler can be measured using, for example, a microscope or a scanning electron microscope (SEM), and the average value can be calculated from a plurality of samples.

[0125] The content of the fibrous thermally conductive filler in the thermally conductive sheet is not particularly limited and can be appropriately selected depending on the intended purpose. However, the content of the fibrous thermally conductive filler is preferably 4% to 40% by volume, more preferably 5% to 30% by volume, and particularly preferably 6% to 20% by volume. If the content is less than 4% by volume, there is a risk of difficulty in achieving sufficiently low thermal resistance. If the content exceeds 40% by volume, there is a risk of affecting the moldability of the thermally conductive sheet and the orientation of the fibrous thermally conductive filler.

[0126] Furthermore, in the thermally conductive sheet, the thermally conductive filler is preferably oriented in one direction or in multiple directions. This is because higher thermal conductivity and / or electromagnetic wave absorption can be achieved by orienting the thermally conductive filler.

[0127] For example, to improve the thermal conductivity of the thermally conductive sheet and thereby enhance the heat dissipation performance of the semiconductor device of the present invention, it is effective to orient the thermally conductive filler substantially perpendicularly to the sheet surface (in the direction connecting the semiconductor element and the conductive cooling member). Alternatively, to enhance the electromagnetic wave shielding performance of the thermally conductive sheet and thereby enhance the electromagnetic wave suppression effect of the semiconductor device of the present invention, the thermally conductive filler may be oriented substantially parallel to the sheet surface.

[0128] Here, the directions "approximately perpendicular to" and "approximately parallel to" the sheet surface refer to directions substantially perpendicular to and substantially parallel to the sheet surface. However, the orientation of the thermally conductive filler may vary slightly during production. Therefore, in the present invention, a deviation of approximately ±20° from the directions perpendicular to and parallel to the sheet surface is permitted.

[0129] The method for adjusting the orientation angle of the thermally conductive filler is not particularly limited. For example, the orientation angle can be adjusted by preparing a sheet-like molded article, which will serve as the raw material for the thermally conductive sheet, and adjusting the cutting angle while the fibrous thermally conductive filler is oriented.

[0130] Inorganic fillers

[0131] Furthermore, the thermally conductive sheet may contain an inorganic filler in addition to the aforementioned binder resin and thermally conductive fibers, because this can further enhance the thermal conductivity of the sheet and improve the strength of the sheet.

[0132] The inorganic filler is not particularly limited in shape, material, average particle size, etc., and can be appropriately selected depending on the intended purpose. Examples of the shape include spherical, elliptical, massive, granular, flat, and needle-shaped. From the perspective of filling properties, the inorganic filler is preferably spherical or elliptical, and particularly preferably spherical.

[0133] Examples of the inorganic filler include aluminum nitride (AlN), silicon dioxide, alumina (aluminum oxide), boron nitride, titanium dioxide, glass, zinc oxide, silicon carbide, silicon (Silicon), silicon oxide, aluminum oxide, and metal particles. These may be used alone or in combination of two or more. Among these, alumina, boron nitride, aluminum nitride, zinc oxide, and silicon dioxide are preferred. From the perspective of thermal conductivity, alumina and aluminum nitride are particularly preferred.

[0134] Furthermore, the inorganic filler may be a filler that has been surface-treated. If the inorganic filler is treated with a coupling agent as the surface treatment, the dispersibility of the inorganic filler is improved, and the flexibility of the thermally conductive sheet is improved.

[0135] The average particle size of the inorganic filler can be appropriately selected depending on the type of the inorganic substance and the like.

[0136] When the inorganic filler is alumina, its average particle size is preferably 1 μm to 10 μm, more preferably 1 μm to 5 μm, and particularly preferably 4 μm to 5 μm. If the average particle size is less than 1 μm, the viscosity may increase, making mixing difficult. On the other hand, if the average particle size exceeds 10 μm, the thermal resistance of the thermally conductive sheet may increase.

[0137] Furthermore, when the inorganic filler is aluminum nitride, its average particle size is preferably 0.3 μm to 6.0 μm, more preferably 0.3 μm to 2.0 μm, and particularly preferably 0.5 μm to 1.5 μm. If the average particle size is less than 0.3 μm, the viscosity may increase, making mixing difficult. If it exceeds 6.0 μm, the thermal resistance of the thermally conductive sheet may increase.

[0138] The average particle size of the inorganic filler can be measured, for example, using a particle size distribution analyzer or a scanning electron microscope (SEM).

[0139] Magnetic metal powder

[0140] Furthermore, the thermally conductive sheet preferably contains magnetic metal powder in addition to the aforementioned binder resin, fibrous thermally conductive fibers, and inorganic filler. The inclusion of the magnetic metal powder can enhance the electromagnetic wave absorptivity of the thermally conductive sheet.

[0141] The type of magnetic metal powder is not particularly limited, other than its electromagnetic wave absorptivity, and any known magnetic metal powder can be appropriately selected. For example, amorphous metal powder or crystalline metal powder can be used. Examples of amorphous metal powder include Fe-Si-B-Cr, Fe-Si-B, Co-Si-B, Co-Zr, Co-Nb, and Co-Ta metal powders. Examples of crystalline metal powder include pure iron, Fe, Co, Ni, Fe-Ni, Fe-Co, Fe-Al, Fe-Si, Fe-Si-Al, and Fe-Ni-Si-Al metal powders. Furthermore, as the crystalline metal powder, microcrystalline metal powders made by adding trace amounts of nitrogen (nitrogen), carbon (carbon), oxygen (oxygen), boron (boron), and the like to crystalline metal powders can also be used.

[0142] In addition, as the magnetic metal powder, a mixture of two or more magnetic metal powders having different materials and / or different average particle sizes may be used.

[0143] In addition, for the magnetic metal powder, it is preferable to adjust the shape to be spherical, flat, or the like. For example, in the case of improving the filling property, it is preferable to use a spherical magnetic metal powder having a particle size of several μm to several tens of μm. Such magnetic metal powder can be produced by, for example, an atomization method or a method of thermally decomposing a metal carbonyl. The atomization method refers to a method that has the advantage of being easy to produce spherical powder, in which molten metal is made to flow out from a nozzle, and a jet of air, water, inert gas, etc. is sprayed onto the molten metal to solidify it into droplets to form a powder. When using the atomization method to produce amorphous magnetic metal powder, in order to prevent the molten metal from crystallizing, it is preferable to set the cooling rate to 1×10 6 (K / s) or so.

[0144] When amorphous alloy powder is produced using the aforementioned atomization method, the surface of the amorphous alloy powder can be made smooth. Thus, using amorphous alloy powder with minimal surface irregularities and a small specific surface area as magnetic metal powder can improve its filling capacity with the binder resin. Furthermore, coupling treatment can further enhance the filling capacity.

[0145] In addition, the thermally conductive sheet may contain other components as appropriate depending on the purpose, in addition to the above-mentioned binder resin, fibrous thermally conductive filler, inorganic filler, and magnetic metal powder.

[0146] Examples of other components include a thixotropy-imparting agent, a dispersant, a curing accelerator, a retarder, a slightly viscous agent, a plasticizer, a flame retardant, an antioxidant, a stabilizer, and a colorant.

[0147] (Conductive member)

[0148] like Figures 1 to 3 As shown, the semiconductor device 1 of the present invention includes a conductive member 11 formed between the upper surface 20 a of the conductive shield 20 and the lower surface 40 b of the conductive cooling member 40 .

[0149] The conductive shield 20 is electrically connected to the conductive cooling member 40 through the conductive member 11, and an electrically closed space can be formed even when the conductive shield 20 has an opening 21. Figure 1 The area A surrounded by the dotted line) can thus improve the electromagnetic noise suppression effect.

[0150] Here, the conductive member 11 is not particularly limited in shape or material as long as it is formed between the upper surface 20 a of the conductive shield 20 and the lower surface 40 b of the conductive cooling member 40 and has conductivity as described above.

[0151] As the shape of the conductive member 11, for example, Figure 4 As shown, a sheet with a hole in the center can also be used. Figures 1 to 3 As shown, the conductive member 11 may be disposed so as to surround the opening 21 of the conductive shield 20 , thereby electrically connecting the conductive shield 20 and the conductive cooling member 40 .

[0152] In addition, regarding the conductive member 11, in addition to Figure 4 In addition to the sheet shape shown, various shapes such as sponge, paste, gel, and line can also be used. Appropriate selection can be made considering the shape of the opening 21 of the conductive shielding cover 20, the distance between the upper surface 20a of the conductive shielding cover 20 and the lower surface 40b of the conductive cooling component 40, etc.

[0153] It should be noted that the conductive member 11, such as Figures 1 to 3 As shown, when viewed in a cross-section along the stacking direction, the spacing P between the conductive members 11 facing each other across the thermally conductive sheet 10 is preferably no greater than 1 / 10 of the wavelength at the maximum frequency of the semiconductor element. This ensures a high electromagnetic wave suppression effect. For example, at a frequency of 1 GHz, the wavelength is 300 mm (speed of light / frequency), so the spacing P is preferably no greater than 30 mm.

[0154] Furthermore, if Figure 4 As shown, the conductive member 11 may be formed as a single member or may be composed of a plurality of members. The conductive member 11 composed of a plurality of members can freely change its shape, which is preferable in terms of manufacturability.

[0155] It should be noted that the shapes of the respective members may be the same, or members of different shapes may be used in combination.

[0156] However, in the case where the conductive component 11 is composed of multiple components, from the perspective of reliably obtaining a high electromagnetic wave suppression effect, the spacing between the components is preferably less than 1 / 10 of the wavelength at the maximum frequency of the semiconductor element, similar to the spacing P between the conductive components 11 opposite to each other across the thermal conductive sheet 10 mentioned above.

[0157] In addition, the conductive member 11 is preferably connected to the conductive shield 20 and the conductive cooling member 40, as shown in FIG. Figure 1 As shown, an electrically closed space (area surrounded by a dotted line) is formed. This is because a more excellent electromagnetic wave suppression effect can be obtained.

[0158] Furthermore, the material constituting the conductive member 11 is not particularly limited as long as it has conductivity.

[0159] For example, in order to reliably achieve electrical connection between the conductive shield 20 and the conductive cooling member 40 , the material of the conductive member 11 preferably contains at least a binder resin and a conductive filler.

[0160] The binder resin included in the material of the conductive component 11 is a cured resin and is the base material of the conductive component 11. From the perspective of moldability and flexibility, the same binder resin as that used in the thermal conductive sheet 10 can be used.

[0161] Should be explained, such as Figure 2 As shown, in the embodiment where the conductive member 11 is in contact with the thermally conductive sheet 10 , the thermally conductive sheet 10 may be made of the same material as the conductive member 11 (ie, the thermally conductive sheet 10 may function as the conductive member 11 ).

[0162] In addition, the conductive filler contained in the material of the conductive component 11 preferably has high conductivity. For example, metal powder, metal film resin, conductive polymer, conductive particles, metal fiber, metal film fiber, and carbon fillers such as graphite, black lead, and carbon fiber can be used.

[0163] Furthermore, the shape of the conductive filler is not particularly limited, and for example, conductive fillers in the form of spheres, ellipsoids, blocks, particles, flats, needles, fibers, coils, or meshes can be used.

[0164] Furthermore, the material of the conductive member 11 may contain various additives in addition to the above-mentioned binder resin and conductive filler.

[0165] Examples of the additives include magnetic powder, thixotropy-imparting agents, dispersants, curing accelerators, retarders, slight viscosity-imparting agents, plasticizers, flame retardants, antioxidants, and stabilizers.

[0166] It should be noted that commercially available materials can be used for the conductive member 11. For example, Shin-Etsu Chemical's EC series (volume resistivity 0.009, 0.025, 0.05 Ωm), which are low-resistivity silicone-based sheets, can be used. Furthermore, anisotropic conductive sheets (for example, Dexerials' CP series), which are often used for electrical connection between electrodes, can be used.

[0167] In addition, the conductive member 11 preferably has a higher conductivity than the thermally conductive sheet 10 in order to achieve an excellent electromagnetic wave suppression effect.

[0168] Specifically, the resistance of the conductive member 11 is preferably 2Ω or less, more preferably 0.2Ω or less, further preferably 0.1Ω or less, particularly preferably 0.01Ω or less, and most preferably 0.001Ω or less. This is because setting the resistance of the conductive member 11 to 2Ω or less can achieve a more excellent electromagnetic wave suppression effect.

[0169] The method for changing the thermal conductivity (resistance value) of the conductive member 11 is not particularly limited, and can be changed by changing the type of binder resin, the material, blending amount, and orientation direction of the thermally conductive filler.

[0170] Furthermore, the conductive member 11 preferably has adhesive or cohesive properties on its surface. This is to improve the adhesion of the conductive member 11 to other members (specifically, to the conductive shield 20 and the conductive cooling member 40), maintain electrical connection even when subjected to external impact, and prevent a reduction in the electromagnetic wave suppression effect.

[0171] There are no particular limitations on the method for imparting adhesiveness or tackiness to the surface of the conductive member 11. For example, the adhesive resin constituting the conductive member 11 may be prepared to enhance adhesion, or the surface of the conductive member 11 may be coated with an adhesive material.

[0172] In addition, the position where the conductive member 11 is provided is not particularly limited as long as it is between the upper surface 20 a of the conductive shield 20 and the lower surface 40 b of the conductive cooling member 40 .

[0173] For example, you can Figure 1 and Figure 3 As shown, the conductive member 11 is provided at a position separated from the thermal conductive sheet 10. Figure 2 As shown, the conductive member 11 is provided at a position so as to be in contact with the thermally conductive sheet 10 .

[0174] Example

[0175] Next, the present invention will be described in detail based on examples. However, the present invention is not limited to the following examples.

[0176] (Example 1)

[0177] In Example 1, a three-dimensional electromagnetic field simulator ANSYS HFSS (manufactured by ANSYS) was used to produce the following Figure 5 The analysis models of the semiconductor device shown in (a) and (b) were used to evaluate the electromagnetic wave suppression effect.

[0178] The thermally conductive sheet 10 used in the semiconductor device model was prepared using a two-component addition-reaction liquid silicone as the binder resin, Fe-Si-B-Cr amorphous magnetic particles with an average particle size of 5 μm as the magnetic metal powder, and pitch-based carbon fibers ("thermal conductive fibers" manufactured by Nippon Graphite Flyer Co., Ltd.) with an average fiber length of 200 μm as the fibrous thermally conductive filler. These components were dispersed in a volume ratio of 35 vol%:53 vol%:12 vol% to prepare a silicone composition (sheet composition). The average thermal conductivity of the resulting thermally conductive sheet (calculated based on the interfacial and internal thermal resistances) was 9.2 W / mK when measured in accordance with ASTM D5470. The magnetic and dielectric properties of the sheet were measured using the S-parameter method. Note that the thickness T of the thermally conductive sheet 10 is set to 0.7 mm.

[0179] Furthermore, the cooling member 40 (heat sink) used in the semiconductor device model was made of an aluminum plate, with a size of 60×120 mm and a thickness of 0.3 mm.

[0180] Furthermore, the shield cover 20 is made of stainless steel with a wall thickness of 0.2 mm, an outer diameter of 20 mm×20 mm×1.2 mm, and a central opening 21. The size of the opening 21 is set to □10 mm: 10 mm×10 mm.

[0181] Furthermore, as the conductive member 11, a sheet-like conductive member was used. The sheet-like conductive member used the same silicone as the thermally conductive sheet 10 as the binder resin, and used carbon fiber as the conductive filler. The outer diameter of the sheet-like conductive member was 16 mm × 16 mm × 0.2 mm, and it had an opening of 12 mm. Furthermore, by varying the content of the conductive filler, the resistance value of the conductive member 11 was produced as follows: Figure 7 Shown are samples of 180Ω, 18Ω, 1.8Ω, 0.18Ω, and 0.018Ω.

[0182] Figure 5 (a) and Figure 5 (b) shows an analytical model of a semiconductor device, and shows the states observed from the upper surface side (front side) and the lower surface side (back side). Figure 5 (a) and Figure 5 In (b), the semiconductor device is drawn in perspective to clarify the positional relationship between the components constituting the semiconductor device.

[0183] It should be noted that the cross-sectional structure of the analysis model is Figure 1 Same, such as Figure 5 (a) and Figure 5 As shown in (b), the semiconductor element 30 is formed by coating a microstrip line (MSL) 31 with a resin mold. This MSL 31 consists of a copper signal line (signal line dimensions: 1 mm × 14 mm × 0.02 mm) on the front side of a dielectric substrate 50 (substrate dimensions: 60 mm × 120 mm × 0.65 mm), and a ground line 60 on the back side. The signal source of the semiconductor element 30 is simplified by this MSL 31, with both ends serving as signal input and output terminals. The main body of the semiconductor element 30 (the portion molded with resin) is made of a dielectric with a relative dielectric constant of 4 and a dielectric loss tangent of 0.01. The main body of the semiconductor element 30 is 16 mm × 16 mm × 0.7 mm.

[0184] Furthermore, for the evaluation of the electromagnetic wave suppression effect, the maximum electric field intensity at a position 3 m away from the semiconductor device was calculated and recorded as the electric field intensity (dBμV / m) corresponding to the frequency. The calculated electric field intensity results are shown in Figure 7 .

[0185] exist Figure 7 , the results are shown when samples having the resistance values ​​of the conductive member 11 of 180Ω, 18Ω, 1.8Ω, 0.18Ω, and 0.018Ω were used.

[0186] according to Figure 7 As a result, it was confirmed that the electromagnetic wave suppression effect can be achieved by providing the conductive member 11, and the smaller the resistance value of the conductive member 11, the better the electromagnetic wave suppression effect.

[0187] Among them, the samples including the conductive member 11 having a resistance value of 0.18Ω and 0.018Ω had a low electric field intensity, and a more excellent electromagnetic wave suppression effect was confirmed.

[0188] Industrial applicability

[0189] According to the present invention, a semiconductor device having excellent heat dissipation and electromagnetic wave suppression effects can be provided.

Claims

1. A semiconductor device, characterized in that: have: a semiconductor element formed on a substrate; a conductive shielding cover connected to the ground wire and having an opening; A conductive cooling member is provided on the upper portion of the conductive shield; a heat conducting sheet formed between the semiconductor element and the conductive cooling member through at least the opening of the conductive shield; as well as A conductive member is formed between the upper surface of the conductive shield and the lower surface of the conductive cooling member to electrically connect the conductive shield and the conductive cooling member. The distance between the conductive members facing each other across the thermally conductive sheet is less than 1 / 10 of the wavelength at the maximum frequency of the semiconductor element. The heat conducting sheet covers a portion of the upper surface of the shielding cover.

2. The semiconductor device according to claim 1, wherein The conductive member is coupled to the conductive shield and the conductive cooling member to form an electrically closed region.

3. The semiconductor device according to claim 1 or 2, wherein: The electrical resistance of the conductive member is 2Ω or less.

4. The semiconductor device according to claim 1 or 2, wherein: The conductive member has adhesiveness or adhesion on the surface.

5. The semiconductor device according to claim 1 or 2, wherein: The conductive member includes a cured product of a resin.

6. The semiconductor device according to claim 1 or 2, wherein: The conductive member includes a conductive filler.

7. The semiconductor device according to claim 1 or 2, wherein: The thermally conductive sheet comprises carbon fibers.

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