JP6627947B1 - Semiconductor module with thermally conductive grease and method of manufacturing the same - Google Patents

Abstract

A semiconductor module capable of effectively suppressing displacement or outflow of a thermally conductive grease from a coating portion during distribution or the like and effectively suppressing outflow of a base oil contained in the thermally conductive grease. provide. A semiconductor module joined to a heat sink via a thermally conductive grease, comprising: a semiconductor module main body; a partition sheet having a plurality of through holes; and a semiconductor module interposed between the semiconductor module main body and the partition sheet. An adhesive layer having a plurality of through holes corresponding to the respective through holes of the partition sheet, wherein the plurality of through holes are larger in diameter than the corresponding through holes of the partition sheet; A base oil diffusion preventing portion provided at an inner edge of the plurality of through holes, and a thermally conductive grease held in the plurality of through holes in the partition sheet so as to be in contact with the base oil diffusion preventing portion, It is a semiconductor module with heat conductive grease. [Selection diagram] Fig. 1

Description

  The present invention relates to a semiconductor module that is joined to a heat sink via a thermally conductive grease.

    2. Description of the Related Art Among semiconductor modules used in electronic devices, there are heat-generating components that generate heat during use, such as a CPU for a computer, a power semiconductor for power control such as a Peltier element, an LED, and an inverter.

  In order to protect these semiconductor modules from heat and allow them to function normally, there is a method of conducting heat generated from the semiconductor modules to a heat sink and dissipating the heat. The thermally conductive grease is applied between the semiconductor module and the heat sink so that the semiconductor module and the heat sink are in close contact with each other, and is used to efficiently conduct heat of the semiconductor module to the heat sink. In recent years, the performance of electronic devices using these semiconductor modules has been improved and small-sized and high-density mounting has been progressed. Therefore, higher thermal conductivity is required for a thermally conductive grease used for heat dissipation measures.

  Thermal conductive grease is prepared by adding inorganic powder fillers with high thermal conductivity (metal oxides such as zinc oxide and aluminum oxide, boron nitride, silicon nitride, and nitride) to base oils such as liquid hydrocarbons, silicone oils, and fluoro oils. It is a grease-like composition in which inorganic nitrides such as aluminum and metal powders such as aluminum and copper are dispersed in a large amount.

  When the thermally conductive grease is assembled to a semiconductor module, first, it is formed into a predetermined pattern such as a dot or a block at an area ratio of about 50% with respect to a heat generating surface of the semiconductor module or a heat sink surface which is in contact with the heat generating surface. Applied. The patterned thermally conductive grease spreads over substantially the entire surface of the semiconductor module by bringing the semiconductor module and the heat sink into close contact.

  For example, Patent Literature 1 discloses a method of applying a thermally conductive grease interposed between a semiconductor module and a cooling body (heat sink) in a predetermined pattern. According to Patent Literature 1, a semiconductor module coated with heat conductive grease in a predetermined pattern improves conductivity from the semiconductor module to a cooling body (heat sink), and transfers heat of the semiconductor module to the heat sink. It is said that it can be conducted efficiently.

  By the way, in recent years, in order to save the trouble of applying the thermal conductive grease by the user and to reduce the variation in the thermal conductive performance due to the application method and conditions, the thermal conductive grease has been previously applied to the surface of the semiconductor module. It may be distributed in a state of a semiconductor module, that is, a semiconductor module with a heat conductive grease.

  In a semiconductor module with heat conductive grease, a phase change type heat conductive grease is used. The phase-change type thermally conductive grease is a solid at room temperature, but can be dissolved in a solvent to form a liquid. Therefore, the semiconductor module with the heat conductive grease can be formed by applying the liquid heat conductive grease to the surface of the semiconductor module and then volatilizing the solvent to solidify the heat conductive grease again.

  As described above, since the phase-change type thermally conductive grease applied to the semiconductor module with the thermally conductive grease is solid at normal temperature, even when the semiconductor module is distributed or the like, its thickness and shape are reduced. It can be maintained stably. When the heat sink is joined to the semiconductor module, the solidified thermally conductive grease is made into a liquid state (Non-Patent Document 1).

Japanese Patent No. 5141371

Fuji Electric Technical Report 2013 VOL. 86 NO. 4P. 263

  Now, in the semiconductor module with the heat conductive grease, when the heat conductive grease is not sufficiently fluidized, the heat conductive grease may be solidified without being sufficiently wetted and spread in the initial joining between the semiconductor module and the heat sink. When the semiconductor module or the like is operated, the heat conductive grease is liquefied again due to the heat generated by the operation. The connection between the semiconductor module and the heat sink may be loosened, and the heat conductive grease may flow out to generate a void in that portion, thereby lowering the heat conductivity between the semiconductor module and the heat sink.

  In order to solve these problems, it is conceivable to use a thermally conductive grease having higher consistency than before. In a semiconductor module with thermal conductive grease obtained by applying high-consistency thermal conductive grease to the surface of a semiconductor module, the thermal conductive grease spreads uniformly and thinly at the initial bonding between the semiconductor module and the heat sink. Become. Thus, it is possible to suppress the heat conductive grease from being too thin due to heat generated during operation.

  However, in a semiconductor module with a thermal conductive grease using a highly conductive thermal grease, the applied thermal conductive grease itself deviates from a predetermined application position due to shaking or vibration during distribution of the semiconductor module. Or flowed out of the semiconductor module. If the application or the outflow of the heat conductive grease occurs, the effect of applying the heat conductive grease in a predetermined pattern for efficient heat conduction may be impaired, and effective heat dissipation through the heat sink may not be performed.

  Furthermore, when the semiconductor module is left for a long time, the base oil contained in the thermally conductive grease may flow out of the semiconductor module. When the base oil contained in the thermal conductive grease spills, the composition of the thermal conductive grease changes and the consistency decreases, and the initial bonding between the semiconductor module and the heat sink does not sufficiently spread the thermal conductive grease. This problem cannot be solved.

  The present invention has been proposed in view of the above-described circumstances, and in a semiconductor module with thermal conductive grease obtained by applying thermal conductive grease to the surface, application of thermal conductive grease during distribution or the like. It is an object of the present invention to provide a semiconductor module capable of effectively suppressing displacement and outflow from a location and effectively preventing outflow of base oil contained in heat conductive grease.

  As a result of repeated studies, the present inventors have bonded a partition sheet having a plurality of through holes to a semiconductor module body via an adhesive layer, and provided a base oil diffusion preventing portion at the inner edge of each through hole of the adhesive layer. The present inventors have found that a semiconductor module with a thermally conductive grease can solve the above-mentioned problems, and have completed the present invention.

  (1) A first aspect of the present invention is a semiconductor module to be joined to a heat sink via a thermally conductive grease, the semiconductor module body, a partition sheet having a plurality of through holes, the semiconductor module body and the partition. A plurality of through-holes corresponding to the respective through-holes of the partition sheet, wherein the plurality of through-holes are larger in diameter than the corresponding through-holes of the partition sheet. Layer, a base oil diffusion preventing portion provided at an inner edge of the plurality of through holes of the adhesive layer, and heat conductivity held in the plurality of through holes in the partition sheet so as to be in contact with the base oil diffusion preventing portion. And a grease, and a semiconductor module with a thermally conductive grease.

  (2) A second aspect of the present invention is the semiconductor module according to the first aspect, wherein the first thermal conductive grease has a consistency of 100 or more and 400 or less.

  (3) A third aspect of the present invention is the semiconductor module with thermally conductive grease according to the first or second aspect, wherein the base oil diffusion preventing portion includes a non-lipophilic material.

  (4) A fourth aspect of the present invention, according to any one of the first to third aspects, further comprising a protective cover adhered to a surface of the partition sheet opposite to an adhesive surface with the module body. It is a semiconductor module with conductive grease.

  (5) A fifth aspect of the present invention is the heat conductive grease according to any one of the first to fourth aspects, wherein an adhesive strength between the partition sheet and the adhesive layer is 0.5 N / 10 mm or more and 5 N / 10 mm or less. It is a semiconductor module with.

  (6) A sixth aspect of the present invention is the semiconductor module with thermally conductive grease used in the first to fifth aspects, wherein the partition sheet is peeled off from the adhesive layer.

  (7) A seventh aspect of the present invention is a semiconductor module to be joined to a heat sink via thermal conductive grease, comprising: a semiconductor module main body; and a partition sheet having a plurality of through holes for holding the thermal conductive grease. Interposed between the semiconductor module main body and the partition sheet, and has a plurality of through holes corresponding to each through hole of the partition sheet, each through hole being larger than the corresponding through hole of the partition sheet. A semiconductor module comprising: an adhesive layer having an enlarged diameter; and a base oil diffusion preventing portion provided on inner edges of a plurality of through holes of the adhesive layer.

  (8) An eighth aspect of the present invention is the method for manufacturing a semiconductor module with thermally conductive grease according to any one of the first to seventh aspects, wherein the base oil diffusion preventing portion is formed on a surface of the semiconductor module main body. Then, the partition sheet is laminated on the surface of the semiconductor module body via the adhesive layer, and a thermally conductive grease is injected into the plurality of through holes in the partition sheet so as to be in contact with the base oil diffusion preventing portion. This is a method for manufacturing a semiconductor module with heat conductive grease.

  ADVANTAGE OF THE INVENTION According to the semiconductor module with a heat conductive grease of this invention, while shifting and flowing out of the thermal conductive grease application location at the time of distribution | circulation etc. are effectively suppressed, It can be suppressed effectively.

It is sectional drawing of the side direction and a top view which show an example of a structure of the semiconductor module with a heat conductive grease. It is sectional drawing which shows an example of a structure of a semiconductor module. It is a top view of the semiconductor module main body in which the base oil diffusion prevention part was formed. It is sectional drawing which shows typically an example of the manufacturing method of the semiconductor module with a heat conductive grease. It is the sectional view in the side direction and the top view showing an example of the composition of the semiconductor module with heat conductive grease concerning other embodiments. It is sectional drawing which shows typically the aspect which joins a semiconductor module and a heat sink via a heat conductive grease.

  Hereinafter, a specific embodiment of the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications for the purpose of the present invention.

{1. Semiconductor module with thermal conductive grease.
FIG. 1 is a diagram illustrating an example of a configuration of a semiconductor module with heat conductive grease according to the present embodiment (hereinafter, also simply referred to as “semiconductor module”). (A) is a cross-sectional view in the side direction of the semiconductor module, (b) is a plan view from above of the semiconductor module ((b) shows a state before the protective cover 14 is attached). There).

  As shown in FIG. 1, the semiconductor module 1 includes a semiconductor module main body 13 and a partition sheet 11. As shown in FIGS. 1A and 1B, the partition sheet 11 has a plurality of through holes 110, and the thermally conductive grease G is injected into each of the through holes 110.

  FIG. 2 is a side sectional view of the semiconductor module 1P in a state before the thermal conductive grease G is injected into the through holes 110 of the partition sheet 11. In the semiconductor modules 1 and 1P, the partition sheet 11 is adhered to the surface of the semiconductor module body 13 via the adhesive layer 12. The adhesive layer 12 is provided with a through-hole 120 so as to correspond to the plurality of through-holes 110 provided in the partition sheet 11, and the base oil diffusion preventing portion 15 is provided at an inner edge of the through-hole 120. ing. Therefore, when the thermally conductive grease G is injected into each through hole 110 of the partition sheet 11 adhered to the semiconductor module body 13 via the adhesive layer 12, the base oil diffusion preventing portion provided at the inner edge of the through hole 120 The heat conductive grease G is held so as to be in contact with 15.

  As described above, the partition sheet 11 having the plurality of through holes 110 is provided on the surface of the semiconductor module main body 13 with the adhesive layer 12 interposed therebetween, and the thermally conductive grease G is provided in each through hole 110 of the partition sheet 11. The semiconductor module 1 with the heat conductive grease is formed by being injected and holding the heat conductive grease G so as to be in contact with the base oil diffusion preventing portion 15.

  The semiconductor module 1 with heat conductive grease is distributed while the partition sheet 11 is adhered. Therefore, since the injected thermal conductive grease G is held by the through holes 110 of the partition sheet 11, even if it is applied to the surface of the semiconductor module body 13 due to vibration or the like at the time of distribution, the applied heat conductive grease G may be displaced from the surface. Outflow of water can be effectively prevented.

  Further, the heat conductive grease G is held so as to be in contact with the base oil diffusion preventing portion 15, so that the base oil contained in the heat conductive grease can be effectively prevented from flowing out.

  When the semiconductor module 1 with the thermally conductive grease is joined to the heat sink 2, the partition sheet 11 is peeled off from the adhesive layer 12 by a user or the like and used (see FIG. 6).

  Hereinafter, each configuration of the semiconductor module 1 with the heat conductive grease will be described in more detail.

<1-1. About each configuration>
(Semiconductor module body)
The semiconductor module main body 13 constitutes the main body of the semiconductor module. For example, a power semiconductor for power control such as a CPU of a computer, a Peltier element, an LED, an inverter, and the like can be given.

  The semiconductor module main body 13 has a surface to which a heat conductive grease G described later is applied. As described above, in the semiconductor module 1 with the heat conductive grease, the semiconductor module main body 13 and the heat sink, which is a heat radiating component, are joined with the heat conductive grease G interposed therebetween.

  Although the shape of the semiconductor module main body 13 is not particularly limited, it is preferable that the semiconductor module main body 13 has a plane having a predetermined area on which the partition sheet 11 can be adhered and the thermal conductive grease G can be applied.

(Compartment sheet)
The partition sheet 11 has a plurality of through holes 110 and is adhered to the surface of the semiconductor module body 13. The partition sheet 11 holds the thermally conductive grease G in the plurality of through holes 110. The partition sheet 11 is adhered to the surface of the semiconductor module main body 13 via the adhesive layer 12. Therefore, the partition sheet 11 is stably fixed to the semiconductor module body 13 and can stably hold the thermally conductive grease G.

  In the semiconductor module 1 with heat conductive grease, since the partition sheet 11 is circulated in a state of being adhered to the semiconductor module body 13, the heat conductive grease G is applied to the semiconductor module body 13 at a predetermined position on the surface of the semiconductor module body 13 by the partition sheet 11. It can be prevented from moving from the outside.

  In the semiconductor module 1 with thermal conductive grease, the partition sheet 11 bonded via the adhesive layer 12 is peeled off from the adhesive layer 12 by a user's hand or the like at the time of use, that is, at the time of bonding to the heat sink 2. Is done.

  The partition sheet 11 is provided with the plurality of through holes 110 as described above. The through holes 110 serve to hold the injected thermally conductive grease G, and define the application pattern of the thermally conductive grease G to the surface of the semiconductor module body 13.

  Specifically, the shape of the through-hole 110 is not particularly limited, and may be any shape such as a circle, an ellipse, and a square. Among them, a circular shape is preferred from the viewpoint that the thermally conductive grease G can be uniformly spread thinly on the surface of the semiconductor module body 13, and for example, a circular shape having a diameter of 1 mm or more and 20 mm or less is preferred.

  In addition, it is preferable that the through-holes 110 are arranged substantially uniformly over the entire partition sheet 11 so that the thermally conductive grease G is spread thinly and uniformly on the surface of the semiconductor module body 13.

  The depth of the through hole 110 (the thickness of the partition sheet 11) is not particularly limited as long as the injected thermal conductive grease G can be stably held, and is, for example, 3 mm or more and 10 mm or less. Is preferred.

  Although the material of the partition sheet 11 is not particularly limited, it is not penetrated by the heat conductive grease, the through hole is easily formed, and the partition sheet 11 can be bent and deformed at the time of attaching to the semiconductor module body 13. The material is preferably a material that is easy to work and has a strength that does not break when peeled from the semiconductor module main body 13, and for example, rubber, an elastomer, a gel, or the like can be selected.

  As described above, the thickness of the partition sheet 11 corresponds to the depth of the through-hole 110, and is a thickness capable of stably holding the thermally conductive grease G, and from the semiconductor module body 13 (from the adhesive layer 12). It is preferable to have a thickness that does not break when peeled. Specifically, as described above, the thickness is preferably, for example, 3 mm or more and 10 mm or less.

(Adhesive layer)
The adhesive layer 12 is interposed between the semiconductor module main body 13 and the partition sheet 11, and adheres the partition sheet 11 to the surface of the semiconductor module main body 13. As a result, the partition sheet 11 is stably fixed to the semiconductor module body 13.

  Further, a plurality of through holes 120 are formed in the adhesive layer 12. The through holes 120 formed in the adhesive layer 12 correspond to the through holes 110 provided in the partition sheet 11, and when the thermally conductive grease G is injected into the through holes 110 of the partition sheet 11, The heat conductive grease G comes into direct contact with the surface of the semiconductor module body 13 through the through holes 120 of the adhesive layer 12 formed so as to correspond to the through holes 110 of the partition sheet 11.

  Each through-hole 120 of the adhesive layer 12 has a larger diameter than the corresponding through-hole 110 of the partition sheet 11, and a base oil diffusion preventing portion 15 is provided at the inner edge of the through-hole 120 of the adhesive layer 12 having the increased diameter. . Accordingly, it is possible to effectively suppress the penetration of the base oil into the adhesive layer.

  The adhesive strength of the adhesive layer 12, that is, the adhesive strength between the adhesive layer 12 and the partition sheet 11 is not particularly limited, but is preferably 0.5 N / 10 mm or more, and more preferably 1.0 N / 10 mm or more. . When the adhesive strength is 0.5 N / 10 mm or more, the partition sheet 11 can be stably bonded and fixed, and can be prevented from peeling off when the semiconductor module 1 with the heat conductive grease is distributed. 11 prevents the held thermally conductive grease G from flowing out.

  On the other hand, the adhesive strength of the adhesive layer 12 is preferably 5 N / 10 mm or less, more preferably 3 N / 10 mm or less. As described above, the partition sheet 11 is peeled off from the adhesive layer 12 when the semiconductor module 1 with the thermally conductive grease is used (when it is bonded to the heat sink 2). At this time, it is preferable that the film can be easily peeled off by the user's hand or the like.

  The adhesive resin constituting the adhesive layer 12 is not particularly limited, and examples thereof include resins such as a cellulose-based adhesive resin and a vinyl alkyl ether-based adhesive resin. Specifically, ethyl cellulose, methyl cellulose, polyvinyl alcohol and the like can be exemplified. Examples of other adhesive resins include an acrylic adhesive resin, a silicone adhesive resin, a urethane adhesive resin, a vinylpyrrolidone adhesive resin, an acrylamide adhesive resin, and a rubber adhesive resin.

(Base oil diffusion prevention section)
The base oil diffusion preventing portion 15 is provided at the inner edge of the through hole in the adhesive layer, and suppresses the outflow of the base oil contained in the thermally conductive grease held in the plurality of through holes in the partition sheet.

  FIG. 3 shows a plan view of the semiconductor module main body 13A on which the base oil diffusion preventing portion 15 is formed. The base oil diffusion preventing portion 15 is formed in a ring shape. The semiconductor module main body 13A is formed by laminating the partition sheets via the adhesive layer so that the outer edge of the base oil diffusion preventing portion 15 and the inner edges of the plurality of through holes of the adhesive layer are in contact with each other. Is obtained before injection of the semiconductor module 1P.

  By holding the thermally conductive grease G so as to be in contact with the base oil diffusion preventing portion 15, the injected thermally conductive grease G is prevented from coming into contact with the adhesive layer 12, and the base oil permeates into the adhesive layer. Can be effectively suppressed.

  The material of the base oil diffusion preventing portion 15a is not particularly limited, but it is preferable to include a material having non-lipophilicity from the viewpoint of preventing the base oil from flowing out. (Oil-based material). The non-lipophilic material includes, for example, a base oil diffusion inhibitor usually contained in a thermally conductive grease.

  Examples of such a base oil diffusion inhibitor include those having a perfluoroalkyl group at one end and a hydrogen group or a phosphate group at the other end. Examples of such a base oil diffusion inhibitor include compounds having a structure represented by the following general formula (1).

_{R- (C n H 2n O)} m -X ··· (1)

  Here, in the above formula (1), R is a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, n is an integer of 1 to 10 and m is 2 to 100. It is the following integer. X is a hydrogen group or a phosphate group.

  The compound having the structure represented by the general formula (1) has a non-lipophilic property, which can effectively prevent the base oil contained in the thermally conductive grease from flowing out.

  The base oil diffusion preventing portion can be formed by applying a coating solution obtained by diluting a base oil diffusion inhibitor in an organic solvent by a conventionally known method to volatilize the organic solvent. As the organic solvent, ethanol, benzene, hexane, methyl ethyl ketone, isopropyl alcohol and the like can be used.

(Thermal grease)
In the semiconductor module 1 with heat conductive grease, the heat conductive grease G is held in the plurality of through holes 110 of the partition sheet 11. The heat conductive grease G is interposed between the semiconductor module main body 13 and the heat sink 2 as a heat radiating component, and conducts heat from the semiconductor module main body 13 to the heat sink 2.

  In the semiconductor module 1 with the heat conductive grease, the partition sheet 11 is adhered to the surface of the semiconductor module main body 13 via the adhesive layer 12, and the heat conductive grease G is filled in the through holes 110 provided in the partition sheet 11. It is characterized by being injected and held in contact with the inner edge of the base oil diffusion preventing portion 15.

  As described above, in the semiconductor module 1 with the thermal conductive grease, since the semiconductor module 1 is circulated without being in contact with the adhesive layer 12, for example, even when the thermal conductive grease G having a high consistency is used, the Leaving the base oil can effectively prevent base oil contained in the thermally conductive grease from flowing out.

  Specifically, the consistency of the thermally conductive grease G may be appropriately selected in consideration of the wet spreading property and the application operability at the time of joining the heat sink 2 and the semiconductor module body 13, for example, 100 or more. Is preferably 200 or more, more preferably 250 or more, and most preferably 300 or more. Further, the consistency of the heat conductive grease G is preferably 400 or less.

  The consistency of the thermally conductive grease G can be adjusted by adjusting the amount of components such as an inorganic powder filler and a base oil described below, or by including a predetermined thickener.

(Protective cover)
Although not an indispensable configuration, the protective cover 14 may be attached to the back surface of the partition sheet 11, that is, the surface opposite to the adhesive surface with the semiconductor module body 13. As described above, in the semiconductor module 1 with thermal conductive grease, the partition sheet 11 is bonded to the semiconductor module main body 13 via the adhesive layer 12, and the thermal conductive grease G is placed in the through holes 110 of the partition sheet 11. It is distributed while being held. At this time, by attaching the protective cover 14 to the back surface of the partition sheet 11, a foreign substance or the like is mixed in the heat conductive grease G held in the through hole 110, or the heat conductive grease G Outflow to the outside can be suppressed.

  The material of the protective cover 14 is not particularly limited, and examples thereof include polyethylene resin, polypropylene resin, polyethylene terephthalate resin, polyethylene naphthalate resin, acrylic resin, polycarbonate resin, and PTFE. For example, it is preferable to use a transparent resin from the viewpoint of observing the state of the heat conductive grease G inside.

  The thickness of the protective cover 14 is not particularly limited, and may be, for example, about 0.1 mm or less.

<1-2. About thermal conductive grease>
Here, the heat conductive grease G constituting the semiconductor module 1 with the heat conductive grease will be specifically described. The heat conductive grease G contains an inorganic powder filler and a base oil, and further contains additives such as a dispersant, a thickener, and a base oil diffusion inhibitor as needed.

(Inorganic powder filler)
Inorganic powder fillers provide high thermal conductivity. The inorganic powder filler is not particularly limited as long as it has a higher thermal conductivity than the base oil, but powders such as metal oxides, inorganic nitrides, metals (including alloys), silicon compounds, and carbon materials are preferably used. Used.

  The content ratio of the inorganic powder filler is not particularly limited, but is preferably 70% by mass or more based on the total amount of the thermally conductive grease. When the content is 70% by mass or more, the thermal conductivity can be sufficiently increased. Further, the content ratio of the inorganic powder filler is preferably 97% by mass or less. When the content is 97% by mass or less, a decrease in the consistency of the thermally conductive grease can be prevented, and the wettability and spreadability on the surface of the semiconductor module main body 13 can be improved.

(Base oil)
The base oil forms the base for the thermally conductive grease. The base oil is not particularly limited, and may be, for example, a hydrocarbon base oil such as a mineral oil, a synthetic hydrocarbon oil, an ester base oil, an ether base oil, a phosphate ester, a silicone oil, a fluorine oil, and the like. .

  Specifically, as the mineral oil, a mineral oil-based lubricating oil fraction is purified by appropriately combining purification methods such as solvent extraction, solvent dewaxing, hydrorefining, hydrocracking, and wax isomerization. 500 neutral oil, bright stock, high viscosity index base oil, and the like. Examples of the synthetic hydrocarbon oils include those obtained by polymerizing alpha olefins produced from ethylene, propylene, butene, and derivatives thereof alone or in a mixture of two or more. Specific examples include polyalphaolefin (PAO) which is an oligomer of 1-decene or 1-dodecene, polybutene which is an oligomer of 1-butene or isobutylene, and a co-oligomer of ethylene, propylene and an alpha olefin. Examples of ester base oils include diesters and polyol esters. Examples of the diester include esters of dibasic acids such as adipic acid, azelaic acid, sebacic acid and dodecane diacid. The polyol ester is an ester of neopentyl polyol having no hydrogen atom on the carbon at the β-position, and specific examples include carboxylic acid esters such as neopentyl glycol, trimethylolpropane, and pentaerythritol.

(Thickener)
The thickener constitutes the base of the heat conductive grease G together with the base oil, and adjusts the hardness of the heat conductive grease.

  The thickener is not particularly limited, and examples thereof include a urea compound, sodium terephthalamate, polytetrafluoroethylene, organized bentonite, silica gel, petroleum wax, polyethylene wax and the like.

(Antioxidant)
The heat conductive grease G can further contain an antioxidant. The antioxidant mainly prevents oxidation of the base oil contained in the thermally conductive grease, increases the stability of the thermally conductive grease, and allows the thermally conductive grease to be used for a long time.

  The antioxidant is not particularly limited, and a known antioxidant can be used. For example, compounds such as hindered amine, hindered phenol, sulfur, phosphorus, benzotriazole, triazine, benzophenone, benzoate, and HALS may be mentioned. Among them, hindered amine antioxidants are particularly preferred because of their high effects. These antioxidants may be used alone or in combination of two or more.

(Dispersant)
The heat conductive grease G can further contain a dispersant. The dispersant is adsorbed on the surface of the inorganic powder filler contained in the grease, and can improve the affinity between the inorganic powder filler and the base oil. That is, the dispersant functions as a surface modifier for the inorganic powder filler, and can improve the consistency of the thermally conductive grease by improving the affinity between the inorganic powder filler and the base oil.

  Examples of the dispersant include polyglycerin monoalkyl ether compounds, compounds having a carboxylic acid structure such as higher fatty acid esters, and polycarboxylic acid compounds. These may be used alone or in combination of two or more. In particular, it is preferable to use a polyglycerin monoalkyl ether compound, a compound having a carboxylic acid structure, and a polycarboxylic acid compound in combination.

(Base oil diffusion inhibitor)
The heat conductive grease G may contain a base oil diffusion inhibitor for the purpose of preventing the base oil constituting the grease from diffusing.

  By including the base oil diffusion inhibitor in the heat conductive grease G, the base oil can be more effectively prevented from diffusing, and the penetration into the adhesive layer 12 can be effectively prevented, and the decrease in the adhesive strength can be prevented. It can be suppressed more effectively.

  As the base oil diffusion preventing agent, the same base oil diffusion preventing agent used for forming the base oil diffusion preventing portion 15 can be used.

(Other components)
The heat conductive grease may contain components (other components) other than the above components as necessary. Other components include a secondary antioxidant, a rust inhibitor, a corrosion inhibitor, a thickener, and the like.

  The heat conductive grease G having the above-described configuration can be manufactured by mixing the components according to a known general method. For example, it can be produced by kneading each component with a planetary mixer, a rotation and revolution mixer, etc. to form a grease, and then kneading the mixture uniformly with three rolls.

<2. Manufacturing Method of Semiconductor Module with Thermal Conductive Grease>
FIG. 4 is a schematic diagram illustrating an example of a flow of a method of manufacturing the semiconductor module 1 with the thermally conductive grease according to the present embodiment.

  Specifically, first, the base oil diffusion preventing portion 15 is formed on the surface of the semiconductor module main body 13 (FIG. 4A). The base oil diffusion preventing portion 15 can be formed by a method in which a coating liquid obtained by diluting a base oil diffusion inhibitor in an organic solvent is applied to the surface of the semiconductor module body 13 through a metal mask and the organic solvent is dried. .

  Next, a plurality of through holes are formed in the sheet to produce the partition sheet 11 (FIG. 4B). As the sheet, a sheet made of rubber, elastomer, gel, or the like can be used as described above. As a method of forming the plurality of through holes 110 in the sheet, a conventionally known method can be used.

  Next, the adhesive layer 12 is laminated on one surface of the partition sheet 11 (FIG. 4C). The method of laminating the adhesive layer 12 includes a method of applying an adhesive resin solution to the surface of the partition sheet 11 through a metal mask to dry volatile components, and a method of forming a plurality of through holes 120 on the surface of the partition sheet 11. A method of bonding the adhesive sheet to the surface of the partition sheet 11 can be used.

  Next, the partition sheet 11 on which the adhesive layer 12 is laminated is laminated and adhered to the surface of the semiconductor module main body 13 such that the inner edge of the through hole 120 of the adhesive layer 12 and the outer edge of the base oil diffusion preventing portion 15 are in contact with each other. (FIG. 4D).

  Next, the thermally conductive grease G is injected into the plurality of through holes 110 in the partition sheet 11 (FIG. 4E). As a method of injecting the thermal conductive grease G into the plurality of through holes, for example, a method of using a grease gun corresponding to the consistency of the grease can be mentioned. Since the adhesive layer 12 has the through holes 120 formed thereon, the thermally conductive grease is directly applied to the surface of the semiconductor module body 13.

  A protective cover is attached to the surface of the partition sheet opposite to the surface to be bonded to the module body (FIG. 4 (f)).

  Through the above steps, the semiconductor module 1 with heat conductive grease can be manufactured as shown in FIG. The method for manufacturing the semiconductor module with the heat conductive grease is not particularly limited to this manufacturing method, and can be implemented with appropriate modifications.

  For example, a method of forming the base oil diffusion preventing portion on the surface of the partition sheet instead of the surface of the semiconductor module main body in FIG. Thereafter, an adhesive layer having a plurality of through holes formed thereon is laminated on the surface of the partition sheet 11 or the surface of the semiconductor module main body 13 in the same manner as described above so that the inner edge of the through hole and the outer edge of the base oil diffusion preventing portion are in contact with each other. The semiconductor module in a state before the thermal conductive grease G is injected may be manufactured by laminating.

<3. Semiconductor Module with Thermal Conductive Grease According to Another Embodiment>
FIG. 5 shows another embodiment of the semiconductor module with heat conductive grease. (A) is a cross-sectional view in the side direction of the semiconductor module, (b) is a plan view from above of the semiconductor module ((b) shows a state before the protective cover 14 is attached). There).

  The semiconductor module 1a with heat conductive grease is characterized in that the base oil diffusion preventing portion 16a is also provided on the inner wall of the through hole 110a of the partition sheet 11a. The base oil diffusion preventing portion 16a is provided on the inner wall of the through hole 110a in addition to the base oil diffusion preventing portion 15a provided on the inner edge of the through hole of the adhesive layer 12a. Of the base oil contained in the thermally conductive grease can be more effectively suppressed.

  The material of the base oil diffusion preventing portion 16a is not particularly limited. However, from the viewpoint of effectively suppressing the outflow of the base oil, the same base oil as the material of the base oil diffusion preventing portion 15a provided on the inner edge of the through hole of the adhesive layer is used. It is preferable that the material is non-lipophilic and has a low affinity for lipophilicity. For example, a base oil diffusion inhibitor such as that contained in a thermally conductive grease can be selected.

  The method of forming the base oil diffusion preventing portion 16a on the inner wall of the through hole 110a is as follows. A coating liquid obtained by diluting a base oil diffusion inhibitor in an organic solvent is applied to the inner wall of the through hole of the partition sheet 11 by a conventionally known method. A method of volatilizing the solvent can be given.

<4. How to Use Semiconductor Module with Thermal Conductive Grease>
FIG. 6 is a diagram for explaining a method of using the semiconductor module with thermally conductive grease according to the present embodiment, that is, an operation for joining the semiconductor module with a heat sink as a heat radiating component.

  First, in the semiconductor module 1 with heat conductive grease, the partition sheet 11 is peeled off from the adhesive layer 12 (FIG. 6A). Peeling can be performed by, for example, a user's hand. As a result, the semiconductor module 1A in which the thermally conductive grease G held by the partition sheet 11 is exposed is obtained (FIG. 6B).

  Next, the heat sink 2 is brought close to the surface on the side where the thermal conductive grease G is exposed (FIG. 6C), and the semiconductor module body 13 and the heat sink 2 are joined. By bonding the heat sink 2 in this manner, the heat conductive grease G spreads thinly on the surface of the semiconductor module body 13 due to the bonding pressure with the heat sink 2. Thereby, the heat of the semiconductor module main body 13 is efficiently conducted to the heat sink 2 via the heat conductive grease G, and the semiconductor module 1A can be radiated.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples of the present invention. In addition, this invention is not limited at all by the following Examples.

[Example 1]
A semiconductor module with a thermally conductive grease was manufactured by the following procedure (see FIG. 4).

  First, a coating liquid for forming a base oil diffusion preventing portion was prepared by dissolving 2% by mass of a perfluoroalkyl group-containing compound having a phosphate group as a base oil diffusion preventing agent in ethanol which is an organic solvent. This coating liquid was applied through a metal mask along the outer edge of the heat conductive grease application area of the semiconductor module main body 13, and then dried in an oven at 65 ° C. for 10 minutes in the atmosphere to evaporate ethanol. A semiconductor module main body 13A in which the base oil diffusion preventing portion 15 shown in FIG.

  Next, a circular sheet having a diameter of 12 mm was formed in a predetermined arrangement in a sheet (silicone rubber) having a thickness of 5 mm to prepare a partition sheet (FIG. 4B).

  Next, an adhesive resin solution was applied to one surface of the prepared partition sheet, and dried at room temperature to remove volatile components to form an adhesive layer (FIG. 4 (c)). The adhesive resin solution is a heated polymer of n-butyl acrylate (45 parts) and vinyl acetate (10 parts), ethyl cellulose (45 parts), and a tackifier with respect to 100 parts (parts by mass, the same applies hereinafter) of ethyl acetate. (Arakawa Chemical Industry Co., Ltd., trade name: Pencel D-135) (25 parts) was used.

  Next, the partition sheet on which the adhesive layer was laminated was adhered to the surface of the semiconductor module body 13A from the side on which the adhesive layer was laminated, and a semiconductor module with a partition sheet was obtained (FIG. 4D).

On the other hand, the following components were mixed to prepare a thermally conductive grease. The consistency was adjusted to 250.
(A) Inorganic powder filler 90.2% by mass
(B) Ester base oil 9.3% by mass
(C) Dispersant (higher fatty acid ester) 0.2% by mass
(D) Thickener (organic treated bentonite) 0.3% by mass

  The inorganic powder filler (A) contained zinc oxide powder having an average particle size of 5 μm, 2 μm, and 0.6 μm at a mass ratio of 4: 3: 3.

  Then, the produced thermal conductive grease is A grease gun corresponding to 3 consistency (consistency range 220 to 250) was used to inject into each through hole of the partition sheet in the semiconductor module with a partition sheet (FIG. 4E).

  After injecting the thermal conductive grease, a protective cover made of a transparent polyethylene film having a thickness of 0.1 mm is provided on the surface of the partition sheet opposite to the surface to be bonded to the semiconductor module body, and an adhesive dedicated to Cemedine for hard-to-adhesive materials. This was mounted via PPX (FIG. 4F), whereby a semiconductor module with thermally conductive grease according to Example 1 was obtained.

(Semiconductor module transportation test)
Five semiconductor modules with thermal conductive grease according to Example 1 obtained by the above procedure were prepared and transported, and the partition sheet was peeled off the semiconductor module with thermal conductive grease after transport, and the semiconductor module body was removed. Was visually observed. The thermal conductive grease application pattern is maintained, and none of the individual thermal conductive greases are connected to each other, effectively suppressing displacement and outflow from the thermal conductive grease application location during transportation It was confirmed that it was possible.

(Thickness measurement test of thermal conductive grease)
The thickness of the heat conductive grease at room temperature when the heat sink was joined to the semiconductor module body via the heat conductive grease and screwed with a specified torque was measured.

  First, the total height H1 of the semiconductor module body and the heat sink was measured. Then, five semiconductor modules with thermally conductive grease according to Example 1 were prepared, the partition sheet was peeled off, the heat sink was joined, and the total height H2 of the heat sink and the semiconductor module body in this state was measured. did.

  The thickness of the thermally conductive grease was calculated by subtracting the measured value H1 from H2 and found to be in the range of 19 μm to 28 μm.

(High temperature storage test)
A high-temperature storage test was performed in which five semiconductor modules with thermal conductive grease according to Example 1 were left at 85 ° C. in the air for 1000 hours. Visual observation of the semiconductor module with the thermally conductive grease after the high-temperature storage test revealed that the component of the thermally conductive grease did not penetrate into the adhesive layer, and the partition sheet 11 did not peel off.

  Further, the adhesion strength measured by a 90-degree peel test (the test method conforms to JIS Z 0237: 2009) is in the range of 0.5 N / 10 mm to 1.5 N / 10 mm for the five samples tested. The partition sheet maintained the close contact with the surface of the semiconductor module body.

[Example 2]
The semiconductor module with thermal conductive grease shown in FIG. 5 was manufactured in the same manner as in Example 1.

  Specifically, a coating solution for forming a base oil diffusion preventing portion is applied to the inner wall of the through hole of the partition sheet 11, and dried in an oven at 65 ° C. for 10 minutes in the atmosphere to volatilize the ethanol. The semiconductor module with the thermally conductive grease of Example 2 was obtained by the same procedure as in Example 1 except that the base oil diffusion preventing portion 16a shown in (2) was formed.

(Semiconductor module transportation test)
A semiconductor module transportation test was performed on the semiconductor module with the thermally conductive grease according to the second embodiment, similarly to the semiconductor module with the thermal conductive grease according to the first embodiment.

  When the semiconductor module after the test was visually observed, the thermal conductive grease application pattern was maintained, and none of the individual thermal conductive greases were connected to each other. It has been confirmed that deviation and outflow from the water can be effectively suppressed.

(Thickness measurement test of thermal conductive grease)
The thickness of the heat conductive grease at room temperature when the heat sink was joined to the semiconductor module body via the heat conductive grease and screwed with a specified torque was measured.

  First, the total height H1 of the semiconductor module body and the heat sink was measured. Then, five semiconductor modules with thermally conductive grease according to Example 1 were prepared, the partition sheet was peeled off, the heat sink was joined, and the total height H2 of the heat sink and the semiconductor module body in this state was measured. did.

  The thickness of the thermally conductive grease was calculated by subtracting the measured value H1 from H2 and found to be in the range of 19 μm to 28 μm.

(High temperature storage test)
A high-temperature storage test was performed on the semiconductor module with the thermal conductive grease according to the second embodiment, similarly to the semiconductor module with the thermal conductive grease according to the first embodiment.

  When the semiconductor module after the test was visually observed, the component of the thermally conductive grease did not penetrate into the adhesive layer, and the partition sheet 11 did not peel.

  Further, the adhesion strength measured by a 90-degree peel test (the test method conforms to JIS Z 0237: 2009) is in the range of 0.5 N / 10 mm to 1.5 N / 10 mm for the five samples tested. The partition sheet maintained the close contact with the surface of the semiconductor module body.

[Comparative Example 1]
A thermal conductive grease was applied to the surface of the semiconductor module in a predetermined pattern using a grease gun without laminating the partition sheets, to obtain a semiconductor module with thermal conductive grease according to Comparative Example 1.

(Semiconductor module transportation test)
A semiconductor module transport test was performed on the semiconductor module with the thermally conductive grease according to Comparative Example 1 in the same manner as the semiconductor module with the thermally conductive grease according to Example 1 described above.

  Visual observation of the semiconductor module after the test confirmed that the coating pattern of the layer of thermal conductive grease was significantly deformed, and that the individual thermal conductive greases were connected. This is presumably because the thermal conductive grease was not held in the through-holes of the partition sheet, so that it was not possible to suppress displacement or outflow of the thermal conductive grease from the application location during transportation. From this test result, it was confirmed that the semiconductor module with the thermally conductive grease according to Examples 1 and 2 can effectively suppress displacement or outflow from the location where the thermally conductive grease was applied during transportation.

[Comparative Example 2]
A semiconductor module with a thermally conductive grease of Comparative Example 2 was manufactured in the same manner as in Example 1 without forming the base oil diffusion preventing portion.

(Semiconductor module transportation test)
A semiconductor module transportation test was performed on the semiconductor module with the thermally conductive grease according to Comparative Example 2 in the same manner as the semiconductor module with the thermally conductive grease according to Example 1 described above.

  When the semiconductor module after the test was visually observed, the application pattern of the thermal conductive grease was maintained, and none of the individual thermal conductive greases was connected to each other. It has been confirmed that deviation and outflow from the water can be effectively suppressed.

(Thickness measurement test of thermal conductive grease)
Similar to the semiconductor module with the thermal conductive grease according to the above-described example, the thickness measurement test of the thermal conductive grease was performed on the semiconductor module with the thermal conductive grease according to Comparative Example 2.

  The thickness of the thermally conductive grease was calculated by subtracting the measured value H1 from H2 and found to be in the range of 45 μm to 68 μm. This is presumably because the base oil component contained in the heat conductive grease separated and flowed out, so that the heat conductive grease became hard and the spreadability was reduced. From this evaluation result, it was confirmed that the semiconductor module with the heat conductive grease according to the example including the base oil diffusion preventing layer can effectively suppress the outflow of the base oil.

(High temperature storage test)
A high-temperature storage test was performed on the semiconductor module with the thermal conductive grease according to Comparative Example 2 in the same manner as the semiconductor module with the thermal conductive grease according to Example 1 described above.

  When the semiconductor module after the test was visually observed, it was confirmed that the component of the thermally conductive grease had penetrated into the adhesive layer, and the partition sheet had been peeled off. This is probably because the base oil component contained in the thermally conductive grease separated and flowed out, so that the base oil permeated into the adhesive layer.

1, 1A Semiconductor module with thermal conductive grease 1P Semiconductor module 11 Partition sheet 110 Through hole 12 Adhesive layer 120 Through hole 13, 13A Semiconductor module body 14 Protective cover 15, 15a, 16a Base oil diffusion preventing layer G Thermal conductive grease 2 heatsink

Claims (8)

A semiconductor module joined to a heat sink via thermal conductive grease,
A semiconductor module body,
A partition sheet having a plurality of through holes,
It is interposed between the semiconductor module body and the partition sheet, and has a plurality of through holes corresponding to each through hole of the partition sheet, and the plurality of through holes are higher than the corresponding through holes of the partition sheet. With an adhesive layer whose diameter has also been expanded,
A base oil diffusion preventing portion provided at an inner edge of the plurality of through holes of the adhesive layer,
A thermally conductive grease held in a plurality of through holes in the partition sheet so as to be in contact with the base oil diffusion preventing portion,
A semiconductor module with thermally conductive grease, comprising: The semiconductor module according to claim 1, wherein a consistency of the heat conductive grease is 100 or more and 400 or less. The semiconductor module according to claim 1, wherein the base oil diffusion preventing portion includes a material having non-lipophilicity. The semiconductor module with heat conductive grease according to any one of claims 1 to 3, further comprising a protective cover adhered to a surface of the partition sheet opposite to a surface to which the module body is adhered. The semiconductor module with thermally conductive grease according to any one of claims 1 to 4, wherein an adhesive strength between the partition sheet and the adhesive layer is 0.5 N / 10 mm or more and 5 N / 10 mm or less. The semiconductor module with heat conductive grease according to any one of claims 1 to 5, wherein the partition sheet is used after being separated from the adhesive layer. A semiconductor module joined to a heat sink via thermal conductive grease,
A semiconductor module body,
A partition sheet having a plurality of through holes in which a thermally conductive grease is held,
It is interposed between the semiconductor module main body and the partition sheet, and has a plurality of through holes corresponding to the respective through holes of the partition sheet, and the plurality of through holes are higher than the corresponding through holes of the partition sheet. With an adhesive layer whose diameter has also been expanded,
A base oil diffusion preventing portion provided at an inner edge of the plurality of through holes of the adhesive layer,
With
A semiconductor module in which a thermally conductive grease is held in a plurality of through holes in the partition sheet so as to be in contact with the base oil diffusion preventing portion. It is a manufacturing method of the semiconductor module with a thermally conductive grease of any one of Claims 1 to 6,
Forming the base oil diffusion preventing portion on the surface of the semiconductor module body,
Laminating the partition sheet on the surface of the semiconductor module body via the adhesive layer,
A method of manufacturing a semiconductor module with thermally conductive grease, wherein thermal conductive grease is injected into a plurality of through holes in the partition sheet so as to be in contact with the base oil diffusion preventing portion.

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