JP2018065921A - Thermosetting adhesive sheet and semiconductor module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosetting adhesive sheet that is easy handle and exhibits excellent adhesiveness to a member of bonding object, and to provide a semiconductor module that is easy to produce.SOLUTION: The present invention provides a thermosetting adhesive sheet in which surface roughness of one side is different from a surface roughness of the other side.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a thermosetting adhesive sheet and a semiconductor module.

Conventionally, a semiconductor module having a semiconductor element encapsulated in a resin mold has been widely used. This semiconductor module generates heat when energized, thereby preventing the semiconductor element from becoming excessively hot. It is equipped with a heat dissipation mechanism.
As this type of semiconductor module, a semiconductor element is mounted on a lead frame formed of a metal block or a thick metal plate, and the heat of the semiconductor element is quickly taken away by these metal members. It has been known.
Further, as a semiconductor module, there is known a semiconductor module including a thin plate-like metal member, one surface of which is exposed to form a heat radiating surface, and a heat radiator such as a heat radiating fin is brought into close contact with the heat radiating surface. ing.
Further, as a semiconductor module, a module in which a radiation fin is integrated is known, and a module in which a large radiation surface is secured by this radiation fin is known.

In a conventional semiconductor module, a metal member such as a lead frame on which a semiconductor element is mounted and a member constituting a heat radiating surface are bonded by a thermosetting adhesive sheet excellent in electrical insulation, and thermosetting bonding is performed. An insulating layer is formed between two metal members by a cured sheet (see Patent Document 1 below).
Since the insulating layer is required to quickly transfer the heat generated by the semiconductor element to the heat radiating surface, the thermosetting adhesive sheet used for this type of application is highly filled with an inorganic filler having a high thermal conductivity. .

JP 2004-165281 A

In manufacturing the semiconductor module, a two-step bonding process is performed in which the thermosetting adhesive sheet is temporarily bonded to the metal member and then bonded.
In this temporary bonding, a plurality of thermosetting adhesive sheets are stacked and accommodated in a magazine, and are sequentially taken out from the magazine with a suction pad or the like attached to a robot arm and bonded to a metal member.
In this bonding, the thermosetting adhesive sheet is sandwiched between one temporarily bonded metal member and the other metal member, and heated and pressed to be bonded to both members.
The thermosetting adhesive sheet contains a lot of inorganic fillers, and it is difficult to exhibit flexibility even when heated. In addition, it is necessary to prevent the thermosetting of the thermosetting adhesive sheet from proceeding excessively in the temporary bonding. Therefore, the thermosetting adhesive sheet cannot be heated until it becomes sufficiently flexible as in the case of actual bonding.
Therefore, in the temporary bonding, there is a fear that an air layer is formed between the thermosetting adhesive sheet and the member due to insufficient adhesion to the partner member to be bonded.
The air layer thus formed may remain after the main bonding and cause a portion having a large thermal resistance to be formed.

In preventing the formation of such an air layer, it is conceivable to make the thermosetting adhesive sheet have a smooth surface and to enhance the adhesion to the member to be bonded to suppress the entrainment of air to the bonding interface.
However, if the surface of the thermosetting adhesive sheet is smooth, the adhesiveness between the thermosetting adhesive sheets is increased, and there is a problem that two or three sheets are taken out with a suction pad at a time when taking out from the magazine. There is a fear.
Even when a suction pad or the like is not used, handling is difficult if the adhesiveness between the thermosetting adhesive sheets is high.
Therefore, this type of thermosetting adhesive sheet is required to improve the handleability while suppressing the formation of an air layer.

Note that the thermosetting adhesive sheet that is desired to exhibit good adhesion to the mating member to be bonded by preventing the formation of an air layer is limited to the one used as a component of the semiconductor module as described above. Is not to be done.
That is, exhibiting good adhesiveness to a member to be bonded while being easy to handle is a matter widely required for thermosetting adhesive sheets.
The present invention has been made in view of the above problems, and it is an object of the present invention to provide a thermosetting adhesive sheet that can be easily handled, and thus to provide a semiconductor module that can be easily manufactured.

  The thermosetting adhesive sheet of the present invention for solving the above problems is a semi-cured thermosetting adhesive sheet containing a thermosetting resin and an inorganic filler having a higher thermal conductivity than the thermosetting resin. A first adhesive surface that is used to bond two members and is bonded to one member of the two members; and a second adhesive surface that is bonded to the other member; The surface roughness (Ra) is 0.4 μm or more and 0.7 μm or less, and the surface roughness (Ra) of the second adhesive surface is 2 μm or more and 20 μm or less.

Since the thermosetting adhesive sheet of the present invention has the first adhesive surface with a small surface roughness, the thermosetting adhesive sheet can be easily brought into close contact with the partner member to be bonded, and the formation of an air layer can be suppressed.
The thermosetting adhesive sheet of the present invention has a second adhesive surface with a large surface roughness.
Accordingly, the second adhesive surface of another thermosetting adhesive sheet can be brought into contact with the first adhesive surface of one thermosetting adhesive sheet, and the overlapping thermosetting adhesive sheets can be in close contact with each other. Can be suppressed.
That is, according to the present invention, it is possible to provide a thermosetting adhesive sheet that exhibits good adhesion to a member to be adhered while being easy to handle.

1 is a schematic front view showing an appearance of a semiconductor module according to an embodiment. 1 is a schematic cross-sectional view showing an internal structure of a semiconductor module according to an embodiment. The schematic sectional drawing which shows the layer structure of a thermosetting adhesive sheet. The schematic sectional drawing which shows the internal structure of the semiconductor module of other embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
First, the semiconductor module will be described.
FIG. 1 is a schematic front view of the semiconductor module of the present embodiment, and FIG. 2 is a schematic cross-sectional view showing the internal structure of the semiconductor module of the present embodiment.
In the following, the “vertical direction” in the front view of FIGS. 1 and 2 may be referred to as “vertical direction”, “vertical direction”, “thickness direction”, and the like of the semiconductor module.
In the following, the “lateral direction” in the front view of FIGS. 1 and 2 may be referred to as “left-right direction”, “horizontal direction”, “planar direction”, and the like of the semiconductor module.

The semiconductor module of this embodiment has a flat rectangular parallelepiped shape that is rectangular in plan view and whose vertical dimension is smaller than the horizontal dimension.
The semiconductor module of this embodiment has a flat bottom surface and side surfaces except that two terminals protrude upward from the top surface.

The semiconductor module 100 of the present embodiment includes the semiconductor element 10 at a position that is a central portion in the thickness direction and a central portion in the planar direction.
The semiconductor module 100 of the present embodiment includes a lead frame 20 serving as a conductive path to the semiconductor element 10, a plate-like metal member (metal plate 30), and an insulating sheet 40 laminated on one surface of the metal plate 30. Is further provided.
The semiconductor module 100 of the present embodiment includes a rectangular frame-shaped case 50 that forms four side surfaces, a semiconductor element 10 and the like embedded in the case 50, and an upper edge portion of the top surface of the semiconductor module 100. And a mold resin 60 for forming the film.

  The semiconductor element 10 of the present embodiment may be a packaged element or a bare chip.

The lead frame 20 of the present embodiment is formed by bending two strip-shaped metal plates substantially at right angles at one place in the length direction, and has a corner portion 21 formed by the bending.
The lead frame 20 is disposed on the semiconductor module 100 so that one of the lead frames 20 with the corner portion 21 as a boundary extends in the horizontal direction and the other extends in the vertical direction.
A portion (horizontal portion 22) extending in the horizontal direction of one of the two lead frames 20 (horizontal portion 22) has the semiconductor element 10 mounted on the upper surface side, and a portion (vertical portion) extending in the vertical direction of the lead frame 20a. The upper end portion of the portion 23) protrudes above the upper edge portion of the mold resin 60 and serves as the terminal.
The lead frame 20 a is provided in the semiconductor module 100 so as to form a conductive path, and has a function of quickly removing heat generated by the semiconductor element 10 from the semiconductor element 10.
In the other lead frame 20b of the two lead frames 20, the upper end portion of the vertical portion 23 is the terminal as in the case of the one lead frame 20a.

The lead frame 20 may be made of a general-purpose metal such as iron, copper, aluminum, nickel, and is preferably made of copper because it is excellent in conductivity and has a large specific heat.
When the lead frame 20 is made of copper, the lead frame 20 does not have to be made of pure copper, and may be made of a copper-based alloy (copper alloy).
The lead frame 20 may be further subjected to a surface treatment such as plating.

The metal plate 30 forms the bottom surface of the semiconductor module 100, and is disposed below the lead frame 20a with the surface on which the insulating sheets 40 are laminated facing upward.
The surface of the metal plate 30 opposite to the surface on which the insulating sheet 40 is laminated is exposed on the lower side of the semiconductor module 100.
The semiconductor module 100 is configured to radiate heat to the outside mainly through the metal plate 30, and utilizes one side of the metal plate 30 whose surface is exposed on the lower side as the main heat radiating surface 100 a.
For example, the semiconductor module 100 may be used in a device including the semiconductor module as a component in a state where a refrigerant circulation type radiator or a heat radiation fin for heat radiation is in contact with the heat radiation surface 100a.
In addition, the semiconductor module 100 can be used in a state in which the heat radiation surface 100a is in contact with a member (for example, a housing) having a larger heat capacity than the semiconductor module among members constituting the device.

The metal plate 30 is preferably excellent in thermal conductivity.
The metal plate 30 is preferably formed of a material that has high surface hardness and is hardly scratched in consideration of adhesion to a radiator or a radiation fin.
In addition, the metal plate 30 is preferably formed of a material that has high rigidity and is unlikely to be warped or twisted in consideration of adhesion to a radiator or a radiator fin.
From such a viewpoint, the metal plate 30 is preferably made of aluminum.
When the metal plate 30 is made of aluminum, the metal plate 30 may be made of pure aluminum or an alloy based on aluminum (aluminum alloy).

In the present embodiment, as will be described in detail later, a thermosetting adhesive sheet 40 ′ for constituting the insulating sheet 40 is temporarily bonded to the metal plate 30 side in a semi-cured state.
When the metal plate 30 is made of aluminum, considering the adhesiveness with the insulating sheet 40, a higher anchor effect can be expected when the surface is made porous by performing an alumite treatment.
However, in the present embodiment, as will be described in detail later, it is required that the semi-cured thermosetting adhesive sheet be quickly and temporarily bonded to the metal plate 30 without excessive heating. At this time, since it is desired that air be removed from the interface with the thermosetting adhesive sheet as much as possible, it is preferable that at least the adhesive surface with the insulating sheet 40 is not in a porous state.
For this reason, when the metal plate 30 is made of aluminum, it is preferable that the surface that is the bonding surface with the insulating sheet 40 is either polished or plated.
Especially, it is preferable that the metal plate 30 is finished by milling and the surface is a milling surface.

Since the surface of the metal plate 30 that is not the surface to be bonded to the insulating sheet 40 constitutes a heat radiating surface as described above, it is preferable to have a high surface hardness.
From such a viewpoint, it is preferable that an alumite treatment is performed on one surface of the metal plate 30.
On the other hand, if one side of the metal plate 30 is a milled surface and the other side is an anodized surface, it is necessary to pay attention to the front and back when handling the metal plate 30.
Therefore, when importance is attached to the ease of handling, it is preferable that both surfaces of the metal plate 30 are finished by milling.

  As the metal plate 30, an aluminum plate made of A1100, A1050, or A5052 having a thickness of 0.1 mm or more and 10 mm or less can be adopted, and the roughness (Ra) of both surfaces is 0.1 μm or more by a face mill or the like. What is surface-finished so that it may become 10 micrometers or less is preferable.

The insulating sheet 40 is provided in the module so as to form an insulating layer that is interposed between the lower surface of the horizontal portion 22 of the lead frame 20 and the upper surface of the metal plate 30 to electrically insulate them. It has been.
The insulating sheet 40 is formed of a thermosetting adhesive sheet made of a resin composition containing a thermosetting resin, and is formed of a cured product obtained by thermosetting the thermosetting adhesive sheet.
Further, the metal plate 30 and the lead frame 20 are bonded together by the insulating sheet 40.
As described above, the semiconductor module 100 of the present embodiment has two metals, that is, the lead frame 20 and the metal plate 30 in the heat dissipation path from the semiconductor element 10 to the heat dissipation surface 100a in order to quickly dissipate the heat of the semiconductor element to the outside. A member is provided.
The semiconductor module 100 has the lead frame 20 as the first metal member provided on the upstream side of the heat dissipation path among the two metal members, and the metal plate 30 as the second metal member on the downstream side of the heat dissipation path. Yes.
The semiconductor module 100 of the present embodiment includes an insulating sheet 40 that is highly filled with an inorganic filler so that the heat flow between the two metal members in the heat dissipation path does not stagnate.

  The thermosetting adhesive sheet of the present embodiment that is thermoset and used as the insulating sheet 40 includes a thermosetting resin and a resin composition that includes an inorganic filler having a higher thermal conductivity than the thermosetting resin. It is formed and is formed of a semi-cured resin composition.

The thermosetting adhesive sheet of this embodiment has a two-layer structure as shown in FIG.
The thermosetting adhesive sheet 40 ′ includes a first layer 41 ′ and a second layer 42 ′ laminated on the first layer 41 ′, and the first layer 41 ′ is a metal plate 30. The second layer 42 ′ is used for bonding to the lead frame 20.
The thermosetting adhesive sheet 40 ′ is a second adhesive used for bonding the first bonding surface 40a ′ used for bonding to one of the two members (metal plate 30) and the other member (lead frame 20). And an adhesive surface 40b '.
Further, in the thermosetting adhesive sheet 40 ′, the surface roughness (Ra) of the first adhesive surface 40a ′ is 0.4 μm or more and 0.7 μm or less, and the surface roughness (Ra) of the second adhesive surface 40b ′ is 2 μm. It is 20 μm or less.

In addition, surface roughness can be calculated | required by measuring arithmetic mean roughness (Ra) based on JISB601-2001, and can be specifically calculated | required by the following measurement conditions.
(Surface roughness measurement conditions)
Measuring equipment: Model name “SURFCOM 1400D-3DF” manufactured by Tokyo Seimitsu Co., Ltd.
Measurement condition:
Cut-off value: 2.5mm
Standard length: 2.5mm
Evaluation length: 12.5mm
Measurement speed: 0.3 mm / s
Stitch tip radius: R 2 μm

The thermosetting adhesive sheet 40 ′ is excellent in adhesion with the metal plate 30 because the first adhesive surface 40 a ′ used for temporary adhesion is excellent in smoothness.
In this regard, it is conceivable that the second adhesive surface 40b 'is also smooth, like the first adhesive surface 40a', but a thermosetting adhesive sheet that is smooth on both sides is composed of a plurality of thermosetting adhesive sheets. When the sheets are stacked, the thermosetting adhesive sheets are in close contact with each other, making it difficult to separate them into individual sheets.
Since the thermosetting adhesive sheet 40 ′ of the present embodiment has a second adhesive surface 40b ′ having a rougher surface than the first adhesive surface 40a ′, the first adhesive surface 40a ′ of one thermosetting adhesive sheet and the other. A plurality of sheets can be overlapped by contacting the second adhesive surface 40b 'of the thermosetting adhesive sheet.
Therefore, in the thermosetting adhesive sheet 40 ′ of the present embodiment, the adhesion between the thermosetting adhesive sheets can be suppressed by the second adhesive surface 40b ′ having a rough surface roughness.
Note that the thermosetting adhesive sheet 40 ′ of the present embodiment is considered to be disadvantageous in terms of adhesion to the lead frame 20 because the surface roughness of the second adhesive surface 40 b ′ is rough. In the main bonding, in which the thermosetting adhesive sheet 40 ′ can be sufficiently heated and softened, the surface roughness of the second adhesive surface 40 b ′ adversely affects the adhesion to the lead frame 20. Risk is low.
That is, the thermosetting adhesive sheet 40 ′ of the present embodiment performs the second adhesion for bonding the other surface side to another member after the first adhesion for bonding one surface side to one member. By using such a method, in the first bonding, the smoothness of the first bonding surface 40a ′ can be used to prevent the progress of curing and to exhibit excellent adhesion to the member.
On the other hand, in the second adhesion, since it is less necessary to consider that the curing proceeds compared to the first adhesion, the thermosetting adhesive sheet 40 ′ can be sufficiently heated, Despite the bonding using the second bonding surface 40b ′ rougher than the first bonding surface 40a ′, excellent adhesion to the member can be exhibited.

As the thermosetting resin that becomes the base resin of the resin composition constituting the thermosetting adhesive sheet 40 ′, it is preferable to employ an epoxy resin.
That is, the resin composition of the present embodiment is preferably an epoxy resin composition.
The epoxy resin is not particularly limited. For example, triphenylmethane type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, modified bisphenol A type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, Various epoxy resins such as a modified bisphenol F type epoxy resin, a dicyclopentadiene type epoxy resin, a phenol novolac type epoxy resin, and a phenoxy resin type epoxy resin can be used.
These epoxy resins may be used alone or in combination of two or more.
Among them, as the epoxy resin, a triphenylmethane type epoxy resin that exhibits excellent fluidity when heated and can be rapidly cured (adhered) is preferable, and the epoxy resin contained in the thermosetting adhesive sheet 40 ′. It is preferable that 80% by mass or more of the triphenylmethane type epoxy resin.
The epoxy resin is more preferably a trishydroxyphenylmethane type epoxy resin.

The resin composition forming the thermosetting adhesive sheet 40 ′ can contain a curing agent for curing the epoxy resin and a curing accelerator.
The curing agent is not particularly limited. For example, phenolic curing agents such as phenol novolac resin, aralkyl type phenol resin, dicyclopentadiene modified phenol resin, naphthalene type phenol resin, bisphenol type phenol resin, diamino Examples thereof include amine curing agents such as diphenylsulfone, dicyandiamide, diaminodiphenylmethane, and triethylenetetramine, and acid anhydride curing agents.
Especially, the hardening | curing agent contained in an epoxy resin composition has a suitable aralkyl type phenol resin (phenol aralkyl resin), such as xylylene novolak phenol and biphenyl novolak phenol.

The curing accelerator is not particularly limited, but amine-based curing accelerators such as imidazoles, triphenyl phosphate (TPP), and boron trifluoride monoethylamine are used for the thermosetting adhesive sheet 40 ′. It is suitable in terms of storage stability, and triphenyl phosphate (TPP) is particularly preferred.
Moreover, tetraphenylphosphonium tetraphenylborate is mentioned as a preferable said hardening accelerator.

  In the epoxy resin composition of this embodiment, even when highly filled with an inorganic filler, in order to demonstrate excellent adhesiveness in a short time of a bonding operation (heating / pressing operation) to a metal member or the like, Those containing trishydroxyphenylmethane type epoxy resin, biphenyl type phenol aralkyl resin, and tetraphenylphosphonium tetraphenylborate are preferable.

Examples of the inorganic filler contained in the thermosetting adhesive sheet 40 ′ together with the epoxy resin include inorganic nitride fillers such as boron nitride, aluminum nitride, and silicon nitride, silicon oxide (silica), aluminum oxide (alumina), and titanium oxide. (Titania), inorganic oxide fillers such as zirconium oxide (zirconia), diamond, talc, clay, calcium carbonate and the like.
Among them, the inorganic filler to be contained in the thermosetting adhesive sheet 40 ′ is preferably any of boron nitride, aluminum oxide, and silicon oxide, and is a mixture containing at least boron nitride and aluminum oxide, Or it is more preferable that it is either a mixture containing at least boron nitride and silicon oxide.
Moreover, as said mixed goods, it is preferable that content of boron nitride is 50 mass% or more and 95 mass% or less.

The inorganic filler preferably has a high content in the thermosetting adhesive sheet 40 ′ in order to make the cured product (insulating sheet 40) exhibit excellent thermal conductivity.
On the other hand, the thermosetting adhesive sheet 40 ′ exhibits excellent adhesiveness, and exhibits thermal resistance at the adhesive interface between the cured insulating sheet 40 and the lead frame 20 and at the adhesive interface between the insulating sheet 40 and the metal plate 30. From the viewpoint of reducing more reliably, the content of the inorganic filler in the thermosetting adhesive sheet 40 ′ is preferably not more than a certain value.
Since the thermosetting adhesive sheet 40 ′ of the present embodiment has the first adhesive surface 40 a ′ having excellent adhesion to the metal plate 30, it is excellent even when the inorganic filler is highly filled in the thermosetting adhesive sheet 40 ′. Adhesiveness can be exhibited.
In this respect, the content of the inorganic filler in the thermosetting adhesive sheet 40 ′ of the present embodiment is preferably 50% by volume to 70% by volume, and more preferably 55% by volume to 65% by volume. preferable.

The cured product after curing the thermosetting adhesive sheet 40 ′ preferably has a thermal conductivity of 5 W / m · K or more, more preferably a thermal conductivity of 7 W / m · K or more, It is particularly preferable to have a thermal conductivity of 10 W / m · K or more.
In the thermosetting adhesive sheet 40 ′, the content of the inorganic filler is limited due to the relationship between adhesiveness and mechanical strength, and the thermal conductivity of the cured product is usually 20 W / m · K or less.

In the thermosetting adhesive sheet 40 ′, a thinner thickness (average thickness) is advantageous in reducing the thermal resistance value from the lead frame 20 to the metal plate 30.
On the other hand, when the thickness of the thermosetting adhesive sheet 40 ′ is excessively thin, handling becomes difficult and it becomes difficult to sufficiently exhibit insulation reliability with respect to the cured insulating sheet 40.
From the above viewpoint, the thickness of the thermosetting adhesive sheet 40 ′ is preferably 10 μm or more and 500 μm or less, and more preferably 50 μm or more and 250 μm or less.
That is, the thickness of the insulating sheet 40 after curing is also preferably 10 μm or more and 500 μm or less, and more preferably 50 μm or more and 250 μm or less.

The resin composition constituting the thermosetting adhesive sheet 40 ′ may contain various additives.
The additives are generally used as plastic compounding chemicals such as dispersants, tackifiers, anti-aging agents, antioxidants, processing aids, stabilizers, antifoaming agents, flame retardants, thickeners, pigments and the like. Things.

However, the thermosetting adhesive sheet 40 ′ is prepared by adjusting the resin composition so that the insulating sheet 40 has a volume resistivity (JIS C 2139) of 1 × 10 ¹² Ω · cm or more. It is preferable that the insulating sheet 40 can exhibit electrical insulation having a volume resistivity of 1 × 10 ¹³ Ω · cm or more.
Note that it is difficult to expect excessive electrical insulation in the insulating sheet 40 highly filled with an inorganic filler, and the volume resistivity of the insulating sheet 40 is normally set to 1 × 10 ¹⁸ Ω · cm or less.
In order for the insulating sheet 40 to exhibit such a volume resistivity, it is usually sufficient to exhibit the volume resistivity as described above at the time of the thermosetting adhesive sheet 40 ′.

The first layer 41 ′ and the second layer 42 ′ of the thermosetting adhesive sheet 40 ′ may have the same resin composition or different resin compositions used for the formation.
Further, the first layer 41 ′ and the second layer 42 ′ of the thermosetting adhesive sheet 40 ′ may have the same thickness or the like.

  The thermosetting adhesive sheet 40 ′ having different surface roughness (Ra) between the first adhesive surface 40a ′ and the second adhesive surface 40b ′ has the same surface roughness due to the thermosetting resin composition containing the inorganic filler. After making a thermosetting adhesive sheet having a surface, the thermosetting adhesive sheet is passed between two rollers having different surface roughnesses, and when passing between the rollers, the thermosetting adhesive sheet is passed by the roller. It can be produced by applying pressure and transferring the shape of the roller surface to a thermosetting adhesive sheet.

  The thermosetting adhesive sheet 40 ′ having different surface roughness (Ra) is obtained by pressing a thermosetting adhesive sheet having the same surface roughness on both sides between two face materials having different surface roughness. Can also be made.

  The thermosetting adhesive sheet 40 ′ having a different surface roughness (Ra) is a resin for forming the second layer 42 ′ while forming a resin composition for forming the first layer 41 ′ into a varnish using a solvent. The composition is made into a varnish using a solvent, each varnish is applied to the surface of two types of separators having different surface roughnesses, and the separator is removed after the dried coating films are adhered to each other. can do.

Thereafter, the thermosetting adhesive sheet 40 ′ can be cut into a predetermined shape and used as a constituent material of the semiconductor module 100.
When the semiconductor module 100 is manufactured, a surface (Ra) having a relatively small surface roughness (Ra) is applied to one of the two members (metal plate 30) to be bonded using the thermosetting adhesive sheet 40 ′. After performing the first bonding for bonding the first bonding surface 40a ′), the other member (lead frame 20) has a relatively large surface roughness (Ra) value (second bonding surface 40b ′). It is possible to employ a method of adhering.

  In the case of producing a plurality of semiconductor modules 100, for example, a plurality of thermosetting adhesive sheets 40 ′ are stacked in a form in which the directions of the first adhesive surfaces 40a ′ are aligned, and the thermosetting adhesive sheets 40 ′ adjacent in the stacking direction are stacked. Are laminated so that the first adhesive surface 40a ′ and the second adhesive surface 40b ′ are in contact with each other, the laminate is stocked in a magazine, and heat is applied from the magazine using a robot arm with a suction pad. The curable adhesive sheet 40 ′ is taken out one by one and supplied to the metal plate 30 to perform temporary bonding (first bonding), and after preparing a plurality of metal plates with thermosetting adhesive sheets by this temporary bonding, If the metal plate with the thermosetting adhesive sheet is bonded to the lead frame (second bonding), the semiconductor module 100 can be efficiently manufactured.

The first bonding can be performed by hot pressing or the like.
On the other hand, it may be difficult to implement the second bonding by hot pressing or the like.
In that case, for example, the metal plate 30 temporarily bonded with a thermosetting adhesive sheet 40 ′ in a pressurizable sealed space such as an injection mold and the lead frame 20 on which the semiconductor element 10 is mounted are cased. 50 and the like, and then the mold resin 60 in a heated and melted state is introduced into this space, and the second bonding can be performed by utilizing the resin pressure and heat capacity of the mold resin 60.
The thermosetting adhesive sheet 40 ′ of the present embodiment has a sufficiently small surface roughness of the first adhesive surface 40 a ′ used for the first adhesion, and therefore does not apply excessive heat or pressure to the metal plate 30. And can be temporarily bonded in a good contact state.
Therefore, thermosetting adhesive sheet 40 'of this embodiment can suppress that a curing reaction advances excessively after the 1st adhesion.
Since the thermosetting adhesive sheet 40 ′ of the present embodiment can suppress the progress of the curing reaction in the first adhesion, the thermosetting resin can exhibit good fluidity in the second adhesion.
Therefore, the thermosetting adhesive sheet 40 ′ of the present embodiment performs the second adhesion at a lower pressure than the first adhesion. For example, the second adhesion is performed by a method using the resin pressure of the mold resin 60. Even if it implements, the outstanding adhesiveness with respect to the lead frame 20 can be exhibited.
As a result, a good heat transfer path from the semiconductor element 10 to the heat radiating surface 100a is formed in the semiconductor module 100 of the present embodiment.

  Note that the thermosetting adhesive sheet 40 ′ of the present embodiment can exhibit the same effect even in a semiconductor module provided with radiating fins 30 x instead of the metal plate 30 as shown in FIG. 4.

Furthermore, various changes can be made to the thermosetting adhesive sheet (thermosetting adhesive sheet) and the semiconductor module of the present embodiment.
That is, the thermosetting adhesive sheet and the semiconductor module of the present invention are not limited to the above examples.
For example, the use of the thermosetting adhesive sheet of the present invention is not limited as a constituent member of a semiconductor module.

A semi-cured thermosetting adhesive sheet having a thickness of 200 μm and a size of 60 mm × 108 mm was prepared using an epoxy resin composition containing an inorganic filler in a proportion of 59% by volume.
The thermosetting adhesive sheet has a surface roughness (Ra) of one adhesive surface (first adhesive surface) of 0.45 μm and a surface roughness (Ra) of the other adhesive surface (second adhesive surface) of 2. It was made to be 0.0 μm.
Separately, an aluminum plate (size: 62 mm × 110 mm) having a thickness of 13 mm that has been double-sided milled (Ra: 0.35 μm) as a metal plate was prepared.

A plurality of the above thermosetting adhesive sheets are prepared and stacked, and a plurality of thermosettings are performed such that the first adhesive surface of one thermosetting adhesive sheet and the second adhesive surface of another thermosetting adhesive sheet are in contact with each other. Adhesive sheets were stacked.
When taking out the stacked thermosetting adhesive sheets in order from the top, the lower thermosetting adhesive sheets could be easily taken out one by one without being accompanied by the thermosetting adhesive sheet to be taken out. .

Next, a test piece was prepared by bonding the thermosetting adhesive sheet to the center of the aluminum plate.
Two types of test pieces were produced: a first test piece in which the first bonding surface was bonded to the surface of the aluminum plate, and a second test piece in which the second bonding surface was bonded.
The test piece was produced using a hot press, and the press conditions for producing the first test piece were the same as the press conditions for producing the second test piece, and the conditions were as follows: .
(Heat press conditions)
Method: Heating for 300 seconds and then cooling for 240 seconds Conditions during heating: 120 ° C. × 6 MPa
Conditions during cooling: 20 ° C. × 6 MPa

  When the prepared test piece was heated in a vacuum oven at 175 ° C. and 5 kPa for 5 minutes, there was a special change in the first test piece in which the first adhesive surface of the thermosetting adhesive sheet was bonded to the aluminum plate. However, the second test piece with the second adhesive surface bonded to the aluminum plate was observed to have a plurality of blisters that were thought to be caused by the presence of air between the aluminum plate and the thermosetting adhesive sheet. It was.

  From the above, it can be seen that according to the present invention, an easy-to-handle thermosetting adhesive sheet can be provided.

DESCRIPTION OF SYMBOLS 10 Semiconductor element 20 Lead frame 30 Metal plate 40 Insulation sheet 40 'Thermosetting adhesive sheet 50 Case 60 Mold resin 100 Semiconductor module

Claims (5)

A thermosetting adhesive sheet in a semi-cured state containing a thermosetting resin and an inorganic filler having a higher thermal conductivity than the thermosetting resin,
A first adhesive surface that is used to bond two members and is bonded to one member of the two members; and a second adhesive surface that is bonded to another member;
The surface roughness (Ra) of the first adhesive surface is 0.4 μm or more and 0.7 μm or less,
A thermosetting adhesive sheet, wherein the surface roughness (Ra) of the second adhesive surface is 2 μm or more and 20 μm or less.   The thermosetting adhesive sheet according to claim 1, wherein the content of the inorganic filler is 50 vol% or more and 70 vol% or less.   The thermosetting resin is a trishydroxyphenylmethane type epoxy resin, and further comprises a biphenyl type phenol aralkyl resin as a curing agent and tetraphenylphosphonium tetraphenylborate as a curing accelerator. Thermosetting adhesive sheet. A semiconductor module comprising a semiconductor element and having a heat dissipation surface for radiating heat generated by the semiconductor element,
A first metal member provided between the semiconductor element and the heat radiating surface; and a second metal member constituting the heat radiating surface, wherein the second metal member and the first metal member are bonded together with an insulating sheet. The semiconductor sheet is a cured product obtained by thermosetting the thermosetting adhesive sheet according to any one of claims 1 to 3.   The semiconductor module according to claim 4, wherein the second metal member is made of aluminum, and at least a surface bonded to the insulating sheet is a milled surface.

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