JP2009130251A - Method of manufacturing heat sink with insulation layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a heat sink with an insulation layer, which allows easy outer shape processing of an insulation sheet and facilitates unification of the outer-shape-processed insulation sheet piece and the heat sink, specifically, a method of manufacturing a heat sink with an insulation layer, which provides a heat sink with an insulation layer, which has a superior heat conductivity, by making the insulation layer with very few voids. <P>SOLUTION: An insulation composition containing an inorganic filler and thermosetting resin is formed into the shape of a sheet to make an insulation sheet. The insulation sheet is outer-shape-processed to cut out the insulation sheet piece, and the insulation sheet piece and the heat sink are unified to form the insulation layer. In order for the insulation layer to be used while being adhered to a module whereon a heating element is mounted, the insulation layer is formed of an uncured form of the thermosetting resin. In this method of manufacturing the heat sink with the insulation layer, a hot press process is executed to hot-press the insulation sheet at least once before the insulation sheet is outer-shape-processed. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing a heat sink with an insulating layer.

Conventionally, a module as an electronic component used in the electronics field is usually used with a heating element such as a semiconductor chip or a power IC mounted thereon. Since it is necessary to dissipate heat generated from the heating element mounted on the module to a radiator or the like to dissipate the heat from the module, a heat radiating member such as a heat sink is generally attached to the module. Accordingly, the heat sink plays a role of efficiently dissipating heat generated from the heat generating element.
By the way, the heat sink is usually made of a conductive metal such as aluminum or copper. Therefore, the heat sink is attached to the heat generating element via an insulating layer in order to prevent a current from flowing out of the module via the heat sink from a semiconductor chip or the like mounted in the module. In this case, of course, the insulating layer is also required to have thermal conductivity in the same manner as the heat sink.

For example, Patent Document 1 describes that a heat sink is attached to a semiconductor element via an insulating layer containing an inorganic filler and a thermosetting resin.
As in Patent Document 1, since the insulating layer contains an inorganic filler in addition to the thermosetting resin, the thermal conductivity of the insulating layer is further increased, and the heat generated in the heating element passes through the heat sink and the insulating layer to form a module. Heat can be efficiently exhausted to the outside.

  Further, an insulating sheet piece cut out in a predetermined shape from an insulating sheet formed of an insulating composition containing an inorganic filler and a thermosetting resin is bonded to a heat sink, and an insulating layer is previously formed on the heat sink. A heat sink with a layer is used.

  However, in this type of insulating sheet, since the inorganic filler contained in the insulating sheet is in the form of particles, a space is easily generated between the inorganic filler and the inorganic filler, and usually contains voids (voids). . If the content of the inorganic filler in the insulating composition is increased in order to further increase the thermal conductivity of the insulating layer, the tendency for voids to be generated becomes more prominent.

An insulating sheet with voids is brittle, and an insulating sheet that has not yet been cured has a relatively low elasticity. For this reason, when the outer shape process is performed to form the insulating sheet piece, the edge portion is broken, and there is a possibility that an extra man-hour may be required at the time of manufacture. Moreover, when the insulating sheet is further thinned in order to increase the thermal conductivity, the fear can be significant.
In addition, in order to reliably integrate the insulating sheet pieces that have voids and have not yet been cured, and the heat sink, the processing conditions for the integration must be set in detail while considering the curing conditions of the thermosetting resin. The manufacturing process can be complicated.
In addition, if there is a relatively large amount of voids in the insulating layer of the heat sink with an integrated insulating layer, the processing conditions for the process of integrating the adhesive layer of the heat sink with an insulating layer on the module must be set in detail. The manufacturing process can be complicated.

JP 2001-057408 A

  In view of the above problems, the present invention provides a heat sink with an insulating layer in which the insulating layer is formed of an uncured thermosetting resin so that the insulating layer can be bonded to the module on which the heating element is mounted. An object of the present invention is to provide a method of manufacturing a heat sink with an insulating layer, in which the outer shape of the insulating sheet is simple and the integrated insulating sheet piece and the heat sink can be easily integrated. Another object of the present invention is to provide a method of manufacturing a heat sink with an insulating layer, which can be a heat sink with an insulating layer having excellent thermal conductivity by using an insulating layer with few voids.

  In order to solve the above-mentioned problems, a method for manufacturing a heat sink with an insulating layer according to the present invention includes forming an insulating sheet by molding an insulating composition containing an inorganic filler and a thermosetting resin into a sheet, Insulating sheet piece is cut out by outer shape processing, the insulating sheet piece is integrated with a heat sink to form an insulating layer, and the insulating layer can be adhered to a module on which a heating element is mounted. A method of manufacturing a heat sink with an insulating layer, wherein the insulating layer is formed with the uncured thermosetting resin, and a hot pressing step of hot pressing the insulating sheet at least once before the outer shape processing. The manufacturing method of the heat sink with an insulating layer characterized by implementing.

  According to the manufacturing method of the heat sink with an insulating layer having the above-described configuration, by performing the hot pressing step, the thermosetting resin of the insulating sheet is appropriately cured, and the elasticity of the insulating sheet is appropriately increased. Moreover, voids in the insulating sheet can be reduced.

  In the method for manufacturing a heat sink with an insulating layer according to the present invention, the insulating layer preferably contains 50 to 65 volume% of the inorganic filler. When the insulating layer contains 50 to 65% by volume of an inorganic filler, that is, by performing a hot pressing step with an insulating sheet containing 50 to 65% by volume of an inorganic filler, voids in the insulating layer Can be significantly reduced.

  Furthermore, in the method for manufacturing a heat sink with an insulating layer according to the present invention, the thermosetting resin is an epoxy resin, and the hot pressing step is hot-pressed at least once at a temperature of 40 to 160 ° C. and a pressure of 4 to 20 MPa. It is preferable to carry out the process. When the thermosetting resin is an epoxy resin, the insulating layer can exhibit better adhesion and better heat resistance. Moreover, in the said hot press process, the hardening of the epoxy resin contained in an insulating sheet becomes more moderate by implementing the process of carrying out the hot press at a temperature of 40-160 degreeC, and the pressure of 4-20 MPa at least once, and an insulating sheet The elasticity of can be more moderate. Moreover, the void in an insulating sheet can be reduced efficiently.

  In the method for manufacturing a heat sink with an insulating layer according to the present invention, in the hot pressing step, it is preferable that a plurality of the insulating sheets are stacked and hot pressed, and the plurality of insulating sheets are laminated and integrated. In the hot pressing step, a plurality of the insulating sheets are overlaid and hot pressed, and the plurality of insulating sheets are laminated and integrated, without performing coating a plurality of times when forming the insulating sheet, etc. A relatively thick insulating sheet can be formed with high accuracy, the thermosetting resin of the insulating sheet can be appropriately cured, the elasticity of the insulating sheet can be increased moderately, and voids in the insulating sheet can be reduced. .

  In the present invention, the term “uncured” represents a state in which a reactive group having curability still remains in the thermosetting resin. The fact that it is “uncured” is confirmed by the DSC measurement described in the example as an index that there is a calorific value.

  By the heat sink manufacturing method according to the present invention, the thermosetting resin of the insulating sheet is appropriately cured by the hot pressing process, and the elasticity of the insulating sheet is moderately increased. There is an effect that it can be easily integrated with the heat sink. In addition, since the voids in the insulating sheet can be reduced, the thermal conductivity of the insulating layer is improved, and the heat conductivity of the heat sink with the insulating layer can be improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

The manufacturing method of the heat sink 6 with an insulating layer according to this embodiment includes an insulating composition preparation step of preparing an insulating composition 2 ′ containing an inorganic filler and a thermosetting resin, and molding the insulating composition 2 ′ into a sheet shape. An insulating sheet forming step for forming the insulating sheet 2, a hot pressing step for performing at least one hot pressing on the insulating sheet 2, and an outer shape processing of the insulating sheet 2 that has been hot pressed to form an insulating sheet piece 3. A cutting-out outer shape processing step and an integration step of integrating the insulating sheet piece 3 and the heat sink 5 are performed.
In addition, the heat sink 6 with the insulating layer after the integration step is performed is provided in the insulating layer 4 so that the insulating layer can be used by being attached to the module on which the heating element is mounted. The thermosetting resin is in an uncured state.

  FIG. 1 shows a coating apparatus in an insulating sheet forming step of forming an insulating sheet 2 by forming an insulating composition 2 ′ containing an inorganic filler and a thermosetting resin into a sheet shape, and FIG. 3 represents an insulating sheet in a hot pressing process in which at least one hot pressing is performed, and FIG. 3 represents the insulating sheet piece 3 in an outer shape processing step of cutting out the insulating sheet piece 3 by externally processing the insulating sheet 2 that has been hot pressed. Reference numeral 4 denotes a heat sink 6 with an insulating layer in an integration process in which the insulating sheet piece 3 and the heat sink 5 are integrated.

In the insulating composition preparation step, the insulating composition 2 ′ can be prepared by mixing an inorganic filler, a thermosetting resin, and, if necessary, a volatile solvent and other components by a general method.
As the insulating composition 2 ′, for example, when the coating is performed by a general coating apparatus as shown in FIG. 1, a liquid insulating composition 2 ′ can be used. In this case, the insulating composition 2 ′ usually contains a volatile solvent. Further, as the insulating composition 2 ′, an insulating composition 2 ′ that does not contain a volatile solvent can be used. In this case, an insulating composition 2 ′ that is solid at normal temperature and melts when heated is preferable. There is an advantage that an insulating sheet can be formed by extrusion molding using the melted insulating composition 2 'or injection molding using a mold.

  The insulating composition 2 ′ is usually in a liquid state at the time of coating, and its viscosity is not particularly limited, but about 1 to 50 Pa · s is appropriate.

As the inorganic filler, although it depends on the thickness of the insulating sheet 2 to be formed, particles having an average particle diameter of 5 to 100 μm can be usually used.
The “average particle diameter” can be determined by, for example, measuring the D50 value by performing particle size distribution measurement using a laser diffraction method.

  The inorganic filler is blended in the insulating composition 2 ′ so as to have a desired content in the insulating layer 4 integrated with the heat sink 5. Specifically, the content of the inorganic filler can be determined by the volume ratio of the inorganic filler in the components excluding the volatile solvent in the insulating composition 2 ′ for forming the insulating sheet 2. This is because, as a general rule, the blending component constituting the insulating sheet 2 and the blending component constituting the insulating layer 4 are generally the same. That is, the content of the inorganic filler in the insulating sheet 2 corresponds in principle to the content of the inorganic filler in the insulating layer 4 integrated with the heat sink 5.

  The inorganic filler contained in the insulating layer 4 is preferably 50% by volume or more, and preferably 65% by volume or less. By being 50 volume% or more, the heat conduction performance of the insulating layer 4 can be further enhanced. Moreover, it is preferable that content of the said inorganic filler is 65 volume% or less at the point of the upper limit which can be contained in the insulating layer 4. The volume means the volume at 20 ° C.

  The inorganic filler preferably contains boron nitride particles in terms of enhancing the thermal conductivity of the insulating layer 4. The content ratio of boron nitride in the inorganic filler is preferably 50% by volume or more. By being 50 volume% or more, there exists an advantage that the heat conductive performance of the insulating layer 4 improves more. In addition, it is preferable that the heat conductivity of the insulating layer 4 is further increased, and 100% by volume, that is, the inorganic filler is made of boron nitride particles.

  Moreover, the said inorganic filler can contain other inorganic compounds other than boron nitride etc. in the range which does not impair the effect of this invention.

  Examples of inorganic fillers other than boron nitride include particles such as aluminum nitride, silicon nitride, gallium nitride, aluminum oxide, silicon carbide, silicon dioxide, magnesium oxide, and diamond.

  The thermosetting resin is not particularly limited, and examples of the thermosetting resin generally used include epoxy resins and phenol resins.

  Among these, as the thermosetting resin, it is preferable to use an epoxy resin because it exhibits excellent adhesion and is excellent in heat resistance and moisture resistance. Moreover, a normal temperature solid epoxy resin is preferred.

The normal temperature solid epoxy resin is preferable when the normal temperature liquid epoxy resin is used in the hot press process as shown in FIG. 2 to reduce the voids of the insulating sheet 2 under heating conditions. This is because when the hot pressing step of hot pressing is performed, the viscosity of the epoxy resin is too low, and the epoxy resin may ooze out from the edge of the release layer 1.
Further, by using a room temperature solid epoxy resin, there is an advantage that processing troubles due to blocking or mold contamination at the time of outer shape processing hardly occur.

On the other hand, voids (voids) or the like in the insulating sheet 2 are difficult to disappear unless an appropriate decrease in viscosity occurs in the insulating sheet 2 when the hot pressing process is performed, and the thermal conductivity of the insulating layer 4 may be reduced. There is also.
As the epoxy resin, a normal temperature solid bisphenol A type epoxy resin having an epoxy equivalent of 450 to 2000 g / eq can be obtained by imparting an appropriate flow property to the polymer composition and suppressing these problems more reliably. And a novolac type epoxy resin having a softening point between 87 ° C. and 93 ° C. in a polyfunctional normal temperature solid having an epoxy equivalent of 160 to 220 g / eq (bisphenol A type epoxy resin / novolak type epoxy resin) = 40/60 It is preferable to use a material mixed at a mass ratio of ˜60 / 40.
In addition, this epoxy equivalent can be calculated | required by JISK7236.

  As described above, when an epoxy resin is used as the thermosetting resin, an epoxy resin curing agent and curing accelerator can be further contained in the insulating composition 2 ′ as other components.

The curing agent is not particularly limited, and examples thereof include amine curing agents such as diaminodiphenyl sulfone, dicyandiamide, diaminodiphenylmethane, and triethylenetetramine, phenol novolac resins, aralkyl-type phenol resins, and dicyclopentadiene-modified phenols. Resin, phenolic curing agents such as naphthalene type phenolic resin and bisphenolic phenolic resin, acid anhydrides and the like can be used.
Of these, phenol novolac resins and diaminodiphenylsulfone are preferred because they are easy to ensure reliability in electrical characteristics.

  The curing accelerator is not particularly limited, but amine-based curing accelerators such as imidazoles, triphenyl phosphate (TPP), and boron trifluoride monoethylamine are preferable in terms of storage stability.

  The volatile solvent that can be blended in the insulating composition 2 'is not particularly limited, but those having a boiling point of 120 ° C or less are preferable in that they volatilize easily after coating. Moreover, it is preferable to use methyl ethyl ketone, acetone, toluene, etc. from the viewpoint that there is no reactivity with the insulating composition 2 '.

  Although not described in detail here, in addition to the thermosetting resin and inorganic filler as described above, the insulating composition 2 ′ for forming the insulating sheet 2 includes a dispersant, a tackifier, an anti-aging agent, Other components generally used as plastic compounding chemicals such as antioxidants, processing aids, stabilizers, antifoaming agents, flame retardants, thickeners, pigments and the like can be added as appropriate within the range not impairing the effects of the present invention. .

  In the insulating sheet forming step, a liquid insulating composition 2 ′ for forming the insulating sheet 2 is applied to one surface side of the release layer 1 by a general coating apparatus as shown in FIG. And the insulating sheet 2 can be formed by drying insulating composition 2 'as needed.

  The thickness of the insulating sheet 2 is not particularly limited, and usually 50 to 300 μm. The thickness of the insulating sheet 2 can be set to a desired thickness, for example, by appropriately setting the thickness when the insulating composition 2 ′ is applied to the release layer 1. Further, for example, when the insulating sheet 2 is formed by extrusion melting or injection molding by heating and melting the solid insulating composition 2 ′ at room temperature, the thickness at the time of the molding is appropriately set. It can be set as the thickness. The thickness of the insulating sheet 2 is preferably 50 μm or more in terms of the lower limit of the thickness that can be easily formed into a sheet shape. Moreover, it is preferable that it is 300 micrometers or less at the point of the upper limit which can apply or shape | mold insulating composition 2 'easily.

  The method for applying the insulating composition 2 'is not particularly limited, and a doctor blade method, a coater method, an extrusion molding method, a screen printing method, a metal mask printing method, or the like can be employed.

As a method of drying the insulating composition 2 ′, a method of drying by heating at normal pressure or a method of volatilizing and removing a volatile solvent in the insulating composition 2 ′ under vacuum conditions can be employed. When a volatile solvent is contained in the insulating composition 2 ′, the insulating composition 2 ′ is usually dried and solidified by this drying.
The temperature for drying the insulating composition 2 ′ is not particularly limited. For example, in the case of drying at normal pressure, the temperature is equal to or higher than the boiling point of the volatile solvent blended in the insulating composition 2 ′. A temperature not higher than the complete curing temperature is preferred, and usually 70 to 130 ° C is appropriate.

  In the insulating sheet forming step, when the release layer 1 is used as shown in FIG. 1, the release layer 1 is, for example, a sheet-like sheet that has been subjected to surface roughening treatment and surface release treatment in addition to untreated surface. Things can be used. The material of the release layer 1 is not particularly limited, and examples thereof include plastics such as polyester, polyolefin, and polyimide, metals such as copper, aluminum, and nickel. Among these, polyethylene terephthalate (PET) is preferable in terms of good peelability, good external formability, and low cost. As thickness of the said peeling layer 1, 25-188 micrometers can be illustrated normally.

  In the insulating sheet forming step, for example, the release layer 1 is fed out on one side and wound up on the other side, and the coating and drying of the liquid insulating composition 2 ′ are continuously performed between the feeding and winding. It is also possible to employ a so-called “roll-to-roll” method with excellent productivity.

  The insulating sheet forming step is not limited to the method of forming the insulating sheet 2 using the insulating composition 2 ′ liquefied with the volatile solvent as described above. For example, a T-die or the like is used. The insulating sheet 2 can also be formed by heating and melting the solid insulating composition 2 ′ at room temperature, such as extrusion molding used or injection molding using a mold.

  The hot pressing step is a step that is performed before the outer shape processing step described later is performed. In the hot pressing step, for example, as shown in FIG. 2A, the two insulating sheets 7 with release layers prepared in the insulating sheet forming step are overlapped so that the insulating sheets 2 face each other, and overlapped. The sheet 2 is hot-pressed and integrated as shown in FIG. 2B, and an insulating sheet having a thickness approximately twice that of the insulating sheet 2 can be prepared. Thereafter, as shown in FIG. 2C, one of the release layers 1 on both sides of the integrated insulating sheet can be peeled off and used in the next outer shape processing step.

  Further, at least one release layer 1 of the approximately double-thickness insulating sheet integrated as described above is peeled off, and the insulating sheet 2 is overlaid on the integrated double-thickness insulating sheet, and further the heat By pressing and integrating, an insulating sheet approximately three times as thick as the insulating sheet 2 can be prepared. Similarly, a thicker insulating sheet can be prepared by increasing the number of times the insulating sheet 2 is stacked. In this way, the thickness of the insulating sheet can be set to a desired thickness.

  Further, an integrated insulating sheet having a thickness larger than that of the insulating sheet 2 can be formed by hot pressing in a state where a plurality of the insulating sheets 2 to which the release layer 1 is not attached are stacked. The insulating sheet 2 or the already integrated insulating sheet may be further overlapped with the insulating sheet that has been once integrated, and further integrated by hot pressing to form a thicker insulating sheet.

  In the hot pressing step, the following advantages are obtained by stacking a plurality of the insulating sheets 2 and hot-pressing and integrating them. For example, as an advantage, when an insulating sheet having a desired thickness cannot be formed due to the limitation of the specification of the apparatus for forming the insulating sheet in the insulating sheet forming step, the coating is performed a plurality of times when the insulating sheet is formed. An example is that an insulating sheet having a desired thickness can be formed with high accuracy without equalization. In addition, as other advantages, the cured state (so-called B stage that has not reached the complete curing) of each of the insulating sheets stacked in a plurality can be made the same as necessary, and the cured state (B An example is that the stage) can be changed.

  In addition, in the said hot press process, it is not necessary to heat-press the insulating sheet 2 repeatedly, and the one insulating sheet 7 with a peeling layer prepared in the said insulating sheet formation process can also be hot-pressed. Alternatively, one insulating sheet 2 without the release layer 1 can be hot-pressed. Thereafter, the single insulating sheet 2 hot-pressed in this way can also be used in the next outer shape processing step.

  Moreover, in the said hot press process, multiple times of hot press can be implemented as needed.

Although it does not specifically limit as conditions of the hot press in the said hot press process, Usually, the temperature of 40-160 degreeC, the pressure of 4-20 MPa, and 2 second-10 hours can be illustrated. When the insulating sheet 2 contains an epoxy resin, it is preferably 40 ° C. or higher in terms of further promoting thermal curing, and the curing reaction of the epoxy resin contained in the insulating sheet 2 proceeds too much, so that the heat sink 5 It is preferable that it is 160 degrees C or less at the point of preventing that it becomes impossible to adhere | attach. Moreover, it is preferable that it is 4 MPa or more at the point which further reduces the void in the insulating sheet 2, and it is preferable that it is 20 MPa or less at the point which is the pressure which can be normally performed with a general apparatus.
Further, it is more preferable to perform hot pressing under reduced pressure in that voids can be efficiently removed.

  After performing the hot pressing step, the epoxy resin contained in the insulating sheet 2 is in an uncured state, more specifically, a semi-cured state that is not completely cured. As the semi-cured state, in the DSC measurement described in the examples, the calorific value of the insulating sheet which is not cured at all is 100%, and the calorific value of the insulating sheet after performing the hot pressing step is 20 to 20%. A range of 85% is preferable. When this calorific value is 20% or more, there is an advantage that the insulating sheet 2 containing the epoxy resin and the heat sink 5 can be more easily integrated, and when it is 85% or less, the insulating sheet 2 and the heat sink 5 are obtained. In the integration step, there is an advantage that the oozing of the epoxy resin is further less likely to occur. In DSC measurement, the lower the calorific value, the more the epoxy resin is cured.

Since the voids of the insulating sheet 2 can be reduced by the hot pressing step, the inorganic fillers included in the insulating sheet 2 are in close contact with each other, and the efficiency of heat conduction between the inorganic fillers can be increased. Therefore, the insulating layer 4 obtained by externally processing the insulating sheet 2 and integrated with the heat sink 5 can have excellent thermal conductivity. As a result, the heat conduction characteristics of the heat sink 6 with an insulating layer can be improved.
In addition, since the voids in the insulating sheet can be reduced, the insulating properties of the insulating layer can be improved. Furthermore, the moisture resistance of the insulating sheet can be further improved.

  In the hot pressing step, when hot pressing is performed in a state where a plurality of the insulating sheets 2 are stacked, the thickness of the insulating sheet (the thickness in the stacked state) at the time of hot pressing is typically exemplified as 100 to 300 μm. The

  Further, the outer shape processing step performed next can be simplified by the hot pressing step. That is, since the insulating sheet 2 contains a thermosetting resin, it can be appropriately cured without adjusting the thermosetting resin completely by adjusting the processing conditions of the hot press process. Therefore, the insulating sheet 2 has an appropriate elasticity, and since the voids are reduced, problems such as the edge portion of the insulating sheet piece 3 being collapsed during the outer shape processing are reduced, and the outer shape processing step is simple. Can be.

  Furthermore, the integration process mentioned later can be easily implemented by the said hot press process. That is, when the insulating sheet 2 containing the thermosetting resin is hot-pressed, the processing conditions of the hot pressing are adjusted, and the thermosetting resin is properly cured without being completely cured in advance. The process can be easily performed. More specifically, since the insulating sheet piece 3 has appropriate elasticity, the thermosetting resin is less likely to ooze out when the insulating sheet piece 3 is pressurized and heated in the integration step. Moreover, the appropriate melting | fusing point, melt viscosity, gelation time, etc. of the insulating sheet piece 3 can be suitably adjusted by changing the process conditions in the said hot press process. Further, by changing the processing conditions in the hot pressing step, the insulating layer 4 of the heat sink 6 with the insulating layer in which the insulating layer 4 and the heat sink 5 are integrated is bonded to a module as an electronic component. The proper melting point, melt viscosity, gelation time and the like of the insulating layer 4 can be appropriately adjusted.

  In the hot pressing step, the thickness of the insulating sheet during the hot pressing (the thickness in the superimposed state) is also described later in that the insulating sheet can be more easily processed in the outer shape processing step described later. It is preferable that it is 50-300 micrometers also in the point that an insulating sheet is integrated with the heat sink 5 more easily in an integration process. When the thickness is 50 μm or more, there is an advantage that the elasticity of the insulating sheet is increased moderately, the outer shape of the insulating sheet is simplified, and the integration of the insulating sheet piece 3 and the heat sink 5 becomes easier. Further, when the thickness is 300 μm or less, there is an advantage that the elasticity of the insulating sheet is moderately reduced, the outer shape of the insulating sheet is simplified, and the integration of the insulating sheet piece 3 and the heat sink 5 becomes easier. .

In addition to the heating device, the hot pressing step can be performed by, for example, a press machine equipped with a decompression device, a press machine equipped with a cooling device, and other multistage press machines.
In addition, as a specific method for performing the hot pressing step, a method of heating and natural cooling, a method of consistently heating and cooling by heat exchange, a method of dividing the heating press and the cooling press, and performing a cooling press after the heating press, etc. Is exemplified.

  In the outer shape processing step, as shown in FIG. 3A, the insulating sheet 2 after the hot pressing step can be cut into a desired size by a general method and easily cut out. That is, since the insulating sheet 2 after the hot pressing process is used, the insulating sheet 2 has an appropriate elasticity, and the insulating sheet 2 can be easily cut into a desired size.

In the outer shape processing step, the insulating sheet 2 after performing the hot pressing step can be used to easily process the insulating sheet 2 in accordance with the outer shape of the heat sink 5. Specifically, for example, as shown in FIG. 3B, the outer shape of the insulating sheet 2 after hot pressing can be easily processed by die cutting. This is because the insulating sheet 2 after the hot pressing process is used, and therefore the insulating sheet 2 has moderate elasticity.
In addition, it does not specifically limit as a specific method in the said external shape process process, Shearing process, laser processing, water jet processing, etc. other than die-cutting process are illustrated.

  In addition, when carrying out the outer shape processing step, the insulating sheet 7 with the release layer in which the insulating sheet 2 is attached to the release layer 1 can be externally processed as shown in FIG. 3, and the release layer 1 is not attached. The outer shape of the insulating sheet 2 can also be processed.

  In the integration step, for example, as shown in FIG. 4A, the insulating sheet piece 3 after performing the outer shape processing step is pressurized and heated while being in contact with the heat sink 5 to insulate from the heat sink 5. The sheet piece 3 can be integrated. When the peeling layer 1 is attached to the insulating sheet piece 3 as shown in FIG. 4, the peeling layer 1 can be peeled from the insulating layer 4 as shown in FIG.

  In the integration step, since the insulating sheet piece 3 that has been subjected to the hot pressing step is used, the integration step of the heat sink 5 and the insulating sheet piece 3 can be performed under relatively simple processing conditions. Specifically, since the thermosetting resin is contained in the insulating sheet piece 3 and the insulating sheet piece 3 is appropriately cured by the hot pressing process, it is necessary to process at an excessive temperature or an excessive pressure. The insulating sheet piece 3 and the heat sink 5 can be integrated at a relatively low temperature or a relatively low pressure. Furthermore, there is little possibility that the thermosetting resin oozes out when the insulating sheet 3 is heated and pressurized. Further, by changing the processing conditions in the integration step, the insulating layer 4 of the heat sink 6 with the insulating layer in which the insulating layer 4 and the heat sink 5 are integrated is bonded to a module as an electronic component. The proper melting point, melt viscosity, gelation time and the like of the insulating layer 4 can be appropriately adjusted.

  Moreover, since the insulating sheet piece 3 that has been subjected to the hot pressing step is used in the integration step, the integration step of the heat sink 5 and the insulating sheet piece 3 can be performed under relatively low pressure processing conditions. . That is, since the voids of the insulating sheet piece 3 are reduced by the hot pressing process, the insulating sheet piece 3 and the heat sink 5 can be integrated relatively easily without applying an excessive pressure.

  Before performing the integration step, if necessary, in order to remove dirt on the surface of the insulating sheet piece 3, the insulating sheet piece 3 is treated with a clean roll or the like to make the insulating sheet piece 3 in a clean state. be able to.

  Note that the insulating layer piece 3 and the heat sink 5 can be integrated using only the insulating sheet piece 3 after the peeling layer 1 is peeled off and peeled off before the integration step. That is, only the insulating sheet piece 3 can be integrated with the heat sink 5 without the release layer 1.

  As the heat sink 5 used in the integration step, an aluminum member, a copper member, or the like can be usually used. Moreover, what was equipped with the radiation fin, the screw hole, and the mold lock process can also be used.

Further, the surface of the heat sink 5 on the interface side with the insulating sheet piece 3 is preferably roughened in order to improve the adhesive force at the interface in the integration with the insulating sheet piece 3.
This surface roughening can be performed by subjecting the surface of the heat sink 5 to sandblasting or oxidation.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

(Example 1)
By the method shown below, the insulating composition preparation step, the insulating sheet formation step, the hot press step, the external shape processing step, and the integration step were carried out to produce a heat sink with an insulating layer.

<Insulation composition>
-Bisphenol A type epoxy resin 50.0 parts by mass (polymer obtained by polycondensation of bisphenol A and epichlorohydrin,
Epoxy equivalent 450-500 [g / eq])
・ Novolak-type epoxy resin 50.0 parts by mass (Phenol novolak and o-cresol novolak are converted to glycidyl ether
Epoxy equivalent 195-220 [g / eq])
・ Amine curing agent (4,4′-diaminodiphenylsulfone) 19.8 parts by mass ・ Amine accelerator (boron trifluoride / monoethylamine complex compound) 1.5 parts by mass ・ Boron nitride filler 241.4 parts by mass (Product name “HP-1” manufactured by Mizushima Alloy Iron Company)
-Methyl ethyl ketone 400.0 mass parts Said insulating composition was mixed under reduced pressure with the disper, and the insulating composition preparation process was implemented.

  The insulating composition was applied to PET (peeling layer) having a thickness of 100 μm with a thickness of 150 μm. As the coating method, a coater method and roll-to-roll were adopted, and the drying conditions were 120 ° C. and 5 minutes. As described above, the insulating sheet forming step was performed.

  Two insulating sheets were faced to each other and hot pressed under the conditions of temperature: 100 ° C., pressure: 8 MPa, time: 20 minutes, and a hot pressing process was performed.

  The outer shape of the insulating sheet prepared according to the outer shape of the heat sink to be integrated later was processed by die cutting, and the outer shape processing step was performed.

The aluminum heat sink of 4 cm × 3 cm × 2 mm was used as the heat sink, and the integration step was performed under the conditions of temperature: 160 ° C., pressure: 2 MPa, time: 3 minutes.
The heat sink with an insulating layer was manufactured as described above.

(Example 2)
A heat sink with an insulating layer was manufactured in the same manner as in Example 1 except that the pressure was 1 MPa in the hot pressing step.

(Comparative Example 1)
A heat sink with an insulating layer was manufactured in the same manner as in Example 1 except that in the hot pressing step, heat was not applied and the temperature was 20 ° C. and the pressure was 8 MPa.

(Evaluation 1)
The insulating layers of “Heatsink with insulating layer” of Examples 1, 2 and Comparative Example 1 produced as described above were completely cured, and the insulating layer density and thermal resistance were measured. The processing conditions for complete curing were set at 170 ° C. for 8 hours. Details of each measurement method will be described below. The results are shown in Table 1.

<Measurement of insulation layer density>
Measurements were made using a gas displacement true density meter. Details of the measurement conditions are shown below.
-Device name: Accupic 1330 manufactured by Micromeritics
・ Filling gas: High purity nitrogen (99.9999% or more)

<Measurement of thermal resistance>
Thermal resistance was measured by a transistor method. Details of the measurement method will be described below with reference to FIG.
The sample for measurement was prepared by peeling off the PET film as a release layer before integrating the insulating sheet and the heat sink, and instead forming a 35 μm thick copper foil and integrally forming it.
The surface electrolytic metal foil is etched to a size of 10 × 15 mm, a transistor (TO-220 type “C2233”) is fixed to this portion with solder, and the heat sink (aluminum plate “A5052”) side is set to “1 W / m · Apply an appropriate amount of “K heat dissipation grease” and then apply it to another heat sink, and in 10W to 10W increments, directly under the heat dissipation part of the power transistor and “thermocouple (K type)” attached to another heat sink. Measure.
“Slope” obtained from a graph plotting “power” (X axis) and “temperature difference between Tj−Ts” (Y axis) is defined as “thermal resistance value of the entire module”. A value obtained by correcting (subtracting) the thermal resistance of heat radiation grease, aluminum, copper foil, etc. from the obtained “thermal resistance value” is defined as “thermal resistance of the insulating layer”. In addition, regarding the contact thermal resistance value between the electrolytic metal foil and the resin composition (insulating layer), the thickness of the resin composition (insulating layer) is arbitrarily changed, and the thermal resistance is measured as “(electrolytic metal foil + resin composition)” The “length” (X axis) and “thermal resistance value” (Y axis) were plotted, and the thermal resistance when X was 0 was determined. Table 1 shows the measurement results of the insulating layer density and the thermal resistance of the insulating layer.

(Test Example 1)
A heat sink with an insulating layer was manufactured in the same manner as in Example 1 except that the hot pressing step and the integration step were performed under the following conditions.
At that time, after the hot pressing process, the progress of curing of the epoxy resin in the insulating sheet piece was evaluated by DSC. Furthermore, it evaluated about whether the insulating sheet piece which implemented the hot press process integrated easily with a heat sink.
-Execution conditions of the hot press process: 80 ° C, pressure: 8 MPa, 10 minutes-Implementation conditions of the integration process: 160 ° C, pressure: 2 MPa, 3 minutes

(Test Example 2)
A heat sink with an insulating layer was manufactured in the same manner as in Test Example 1 except that the hot pressing process was performed at 180 ° C. for 15 minutes in the hot pressing process.

(Test Example 3)
A heat sink with an insulating layer was manufactured in the same manner as in Test Example 1 except that the hot pressing process was performed at 40 ° C. for 5 minutes in the hot pressing step.

(Evaluation 2)
In Test Examples 1 to 3, the degree of change in the semi-cured state of the insulating sheet due to the difference in the hot press conditions was evaluated by DSC measurement. In the process of integrating the insulating sheet piece and the heat sink, Table 2 shows the results of evaluating the influence of the difference on the ease of implementation of the integration process.

<Differential scanning calorimetry (DSC)>
The calorific value of 100 ° C. to 280 ° C. was measured by DSC.
Measuring instrument: differential scanning calorimeter (“Pyris 1” manufactured by PerkinElmer)
-Measurement temperature range: 30-300 ° C
-Temperature rising rate: 10 ° C./min.
The heat generation amount of the insulating sheet that was not cured at all was set to 100%, and this insulating sheet was manufactured as follows. The insulating composition preparation step was performed in the same manner as in Example 1. After applying the insulating composition in the same manner as in Example 1, the coated insulating composition was placed under reduced pressure to remove volatile components. An insulating sheet was produced. The insulating sheet was used as an uncured insulating sheet, and the DSC was performed to determine the heat generation amount.

The schematic sectional drawing showing a coating device. The schematic sectional drawing showing the insulating sheet before hot press and after hot press. Schematic showing the insulation sheet piece by which the external shape was processed. The schematic sectional drawing showing the heat sink before integrating with an insulating sheet piece, and the heat sink with an insulating layer. Schematic showing arrangement | positioning in a thermal resistance test.

Explanation of symbols

  1: Insulating sheet, 2: Insulating sheet, 2 ': Insulating composition, 3: Insulating sheet piece, 4: Insulating layer, 5: Heat sink, 6: Heat sink with insulating layer, 7: Insulating sheet with releasing layer

Claims (4)

An insulating composition containing an inorganic filler and a thermosetting resin is formed into a sheet shape to form an insulating sheet (2), the insulating sheet (2) is trimmed to cut out an insulating sheet piece (3), The insulating sheet piece (3) is integrated with the heat sink (5) to form the insulating layer (4), and the insulating layer is attached to the module on which the heating element is mounted so that it can be used. A method of manufacturing a heat sink with an insulating layer, wherein the insulating layer (4) is formed of the uncured thermosetting resin,
A method of manufacturing a heat sink with an insulating layer, wherein a heat pressing step of hot pressing the insulating sheet (2) at least once is performed before the outer shape processing.   The manufacturing method of the heat sink with an insulating layer of Claim 1 in which the said insulating layer (4) contains the said inorganic filler 50 to 65 volume%.   The insulating layer according to claim 1 or 2, wherein the thermosetting resin is an epoxy resin, and the step of hot pressing at a temperature of 40 to 160 ° C and a pressure of 4 to 20 MPa is performed at least once in the hot pressing step. Manufacturing method of heat sink.   The manufacturing of the heat sink with an insulating layer according to any one of claims 1 to 3, wherein in the hot pressing step, a plurality of the insulating sheets are overlapped and hot pressed, and the plurality of insulating sheets are laminated and integrated. Method.

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