Method for manufacturing a conductor-filled through-hole substrate and a conductor-filled through-hole substrate

Abstract

To provide a method for manufacturing a conductor-filled through-hole substrate with sufficient conductivity and excellent connection reliability in a productive manner.SOLUTION: A manufacturing method for a conductor-filled through-hole substrate includes a preparation step for preparing a through-hole substrate that includes an insulating base provided with a through-hole and through both main surfaces of which a through-hole penetrates, a copper sintered body forming step for forming a sintered copper body having a porous structure so as to fill at least the through-hole, a resin impregnation step for impregnating the sintered copper body with a curable resin composition, and a resin curing step for forming a conductor including a sintered copper body filled with a porous resin-cured material by curing the curable resin composition impregnated in the sintered copper body.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a conductor-filled through-hole substrate and a conductor-filled through-hole substrate.

Background Art

[0002] In recent years, in order to miniaturize, enhance functionality, and integrate electronic devices or components, a method has been used in which a through-hole (via hole) is formed in an insulating substrate, and a conductor is provided in the through-hole to electrically connect both main surfaces of the substrate.

[0003] As a method for providing a conductor in a through-hole, a method is known in which an active metal layer is provided on the wall surface of the through-hole of an insulating substrate, and the through-hole is filled with copper by copper plating. However, when the aspect ratio of the through-hole increases due to thinning of the insulating substrate and reduction of the diameter of the through-hole, voids and dimples are likely to occur in the conductor. In order to suppress such problems, Patent Document 1 below proposes a method of filling a through-hole with copper by direct current cycle copper electroplating including applying a high current density for a predetermined period and applying a low current density for a predetermined period.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the method described in Patent Document 1 has a problem in terms of productivity because the working time becomes long since it is necessary to perform plating while suppressing the deposition rate of the copper film.

[0006] On the other hand, a conductor-filled through-hole substrate in which the through-holes are filled with a conductor not only has sufficient conductivity but also is required to have excellent connection reliability in that the resistance value hardly increases even when subjected to temperature changes.

[0007] Therefore, one aspect of the present invention aims to provide a method capable of producing a conductor-filled through-hole substrate having sufficient conductivity and excellent connection reliability with good productivity, and a conductor-filled through-hole substrate having sufficient conductivity and excellent connection reliability.

Means for Solving the Problems

[0008] As a result of intensive studies to achieve the above object, the present inventors formed a copper sintered body having a porous structure in the through-holes of a through-hole substrate, then impregnated this copper sintered body with a curable resin composition, and cured this to form a conductor comprising a copper sintered body filled with a resin cured product in a porous manner. And the present inventors found that a conductor-filled through-hole substrate in which the through-holes are filled with such a conductor exhibits a sufficiently low initial resistance value and the resistance value hardly increases even in a temperature cycle connection reliability test, and thus completed the present invention.

[0009] That is, one aspect of the present disclosure provides the following invention. [1] A preparation step of preparing a through-hole substrate including an insulating substrate provided with through-holes and having the through-holes communicating with both main surfaces, A copper sintered body forming step of forming a copper sintered body having a porous structure so as to fill at least the through-holes, A resin impregnation step of impregnating the copper sintered body with a curable resin composition, A resin curing step of curing the curable resin composition impregnated in the copper sintered body to form a conductor comprising the copper sintered body filled with a resin cured product in a porous manner, A method for manufacturing a conductor-filled through-hole substrate, comprising:

[0010] [2] The method according to [1], wherein the filling rate of the resin cured product in the conductor is 80% by volume or more based on the volume of the internal space of the porous material. [3] The method according to [1] or [2], wherein the porosity of the copper sintered body is 1 to 15% by volume based on the volume of the copper sintered body. [4] The method according to any one of [1] to [3], wherein in the copper sintered body forming step, the copper sintered body is formed so as to cover at least a part of the main surface of the through-hole substrate. [5] The method according to [4], further comprising a conductor removing step of removing at least a part of the conductor formed on the main surface of the through-hole substrate. [6] The method according to [5], wherein the removing means in the conductor removing step is one or more selected from the group consisting of etching, mechanical polishing, and chemical mechanical polishing. [7] The method according to any one of [1] to [6], wherein the through-hole substrate includes a metal film provided at least on the wall surface of the through-hole. [8] The method according to any one of [1] to [7], wherein the ratio L / D of the hole length L to the hole diameter D of the through-hole is 10 or more.

[0011] [9] The copper sintered body forming step is a copper paste filling step of filling the through-hole of the through-hole substrate with a copper paste containing copper particles, and a copper paste firing step of firing the copper paste to form the copper sintered body, and has the method according to any one of [1] to [8].

[10] The method according to [9], wherein the copper paste contains, as the copper particles, first copper particles having a particle size of 0.8 μm or more and second copper particles having a particle size of 0.5 μm or less.

[11] The method according to

[10] , wherein the first copper particles are flat.

[12] The method according to any one of [9] to

[11] , wherein the copper paste is fired under a pressure of 0.1 MPa or more.

[13] The method according to any one of [9] to

[12] , wherein the copper paste is fired in an atmosphere containing nitrogen or hydrogen.

[0012] Moreover, one aspect of the present disclosure provides the following invention.

[14] A through-hole substrate including an insulating substrate provided with through-holes, wherein the through-holes communicate with both main surfaces, and a conductor filling the through-holes. The conductor-filled through-hole substrate, wherein the conductor includes a copper sintered body having a porous structure and a cured resin filled in the pores of the copper sintered body.

[0013]

[15] The conductor-filled through-hole substrate according to

[14] , wherein the filling rate of the cured resin in the conductor is 80% by volume or more based on the volume of the internal space of the pores.

[16] The conductor-filled through-hole substrate according to

[14] or

[15] , wherein the through-hole substrate includes a metal film provided at least on the wall surface of the through-holes.

[17] The conductor-filled through-hole substrate according to any one of

[14] to

[16] , wherein the ratio L / D of the hole length L to the hole diameter D of the through-holes is 10 or more.

[18] The conductor-filled through-hole substrate according to any one of

[14] to

[17] , wherein the conductor covers at least a part of the main surface of the through-hole substrate.

Advantages of the Invention

[0014] According to one aspect of the present invention, there is provided a method capable of producing a conductor-filled through-hole substrate having sufficient conductivity and excellent connection reliability with good productivity, and a conductor-filled through-hole substrate having sufficient conductivity and excellent connection reliability.

[0015] According to the above method, a conductor-filled through-hole substrate excellent in airtightness and non-permeability (the property that liquid does not penetrate) can be provided.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

[0017] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and duplicate explanations are omitted.

[0018] (Method for Manufacturing a Conductor-Filled Through-Hole Substrate) FIGS. 1 to 4 are schematic diagrams showing a method for manufacturing a conductor-filled through-hole substrate according to an embodiment.

[0019] The method for manufacturing a conductor-filled through-hole substrate according to the present embodiment includes a preparation step of preparing an insulating substrate provided with through-holes and having through-holes communicating with both main surfaces, a copper sintered body forming step of forming a copper sintered body having a porous structure so as to fill at least the through-holes, a resin impregnation step of impregnating the copper sintered body with a curable resin composition, By curing the curable resin composition impregnated in the copper sintered body, a resin curing step of forming a conductor including the copper sintered body filled with a porous resin cured product is performed, a conductor removing step of removing at least a part of the conductor formed on the main surface of the through-hole substrate, is provided.

[0020] <Preparation Step of Through-Hole Substrate> In this step, as shown in Fig. 1(a), a through-hole substrate 40 having an insulating substrate 1 provided with through-holes 30 and a metal film 2 provided on the wall surface of the through-holes and the surface of the insulating substrate 1 can be prepared. The through-holes 30 communicate with both main surfaces of the through-hole substrate 40.

[0021] Examples of the insulating substrate 1 include insulating substrates such as a silicon substrate, a glass substrate, a ceramic substrate, and a glass epoxy resin substrate. Figs. 1 to 4 show an embodiment using a silicon substrate as the insulating substrate 1.

[0022] The thickness of the insulating substrate 1 may be 100 μm or more, 200 μm or more, 300 μm or more from the viewpoint of suppressing warping of the substrate after sintering, and may be 800 μm or less, 300 μm or less, 200 μm or less, or 100 μm or less from the viewpoint of reducing the weight and increasing the density of the substrate.

[0023] The upper limit value of the hole diameter of the through-holes 30 may be 200 μm or less, 100 μm or less, or 60 μm or less from the viewpoint of achieving high density of the resulting semiconductor device when the insulating substrate 1 is a silicon substrate. The lower limit value of the hole diameter of the through-holes 30 is not particularly limited, but may be 20 μm or more, or 50 μm or more.

[0024] The ratio L / D of the hole length L to the hole diameter D of the through hole 30 may be 1 or more, 5 or more, or 10 or more from the viewpoint of achieving high density of the resulting semiconductor device. The upper limit value of the aspect ratio L / D of the through hole 30 is not particularly limited, but may be 15 or less, may be 10 or less, or may be 5 or less. The hole length L of the through hole 30 may be the thickness of the insulating substrate 1. In this case, the ratio T / D of the thickness T of the insulating substrate 1 to the hole diameter D of the through hole 30 may also be within the above range.

[0025] When the insulating substrate 1 is a silicon substrate, the number of through holes 30 provided in the through hole substrate is 100 or more or 300 or more per 1 cm of the main surface of the substrate from the viewpoint of achieving high density of the resulting semiconductor device. 2 per.

[0026] The metal film 2 may be provided on both main surfaces of the insulating substrate 1 and the wall surface of the through hole 30, may be provided on at least one main surface of the insulating substrate 1 and the wall surface of the through hole 30, may be provided only on the wall surface of the through hole 30, or may not be provided. In the embodiment shown in Fig. 1(a), the through hole substrate 40 includes a metal film 2 on both main surfaces of the insulating substrate 1 and the wall surface of the through hole 30.

[0027] Examples of the metal film 2 include titanium, nickel, chromium, copper, aluminum, palladium, platinum, and gold. From the viewpoint of adhesion, the metal film 2 is preferably a film formed by laminating titanium, nickel, and copper in this order. When the material of the surface of the main surface of the insulating substrate 1 is silicon, the surface of the insulating substrate 1 is oxidized to form silicon oxide, and a titanium layer is formed on the silicon oxide, thereby improving the adhesion. Further, by providing a nickel layer on the titanium layer and a copper layer thereon, diffusion of copper into the insulating substrate 1 can be suppressed as compared with the case where a copper layer is directly provided on the titanium layer. Furthermore, by providing a copper layer on the surface, the adhesion between the copper sintered body formed in the copper sintered body forming step described later and the through hole substrate is improved.

[0028] <Copper sintered body forming step> In this step, a copper sintered body having a porous structure is formed so as to fill at least the through holes. In the present embodiment, the copper sintered body may be formed so as to cover at least a part of the main surface of the through-hole substrate. In this case, a conductor for filling the through holes of the through-hole substrate can be formed, and a conductor can also be provided on the main surface of the through-hole substrate. The conductor provided on the main surface of the through-hole substrate can form wirings and electrodes.

[0029] The copper sintered body forming step may include a copper paste filling step of filling the through holes of the through-hole substrate with a copper paste containing copper particles, and a copper paste firing step of firing the copper paste to form the copper sintered body. When the copper sintered body is formed on the main surface of the through-hole substrate, in the copper paste filling step or thereafter, a layer of copper paste can be provided on both main surfaces of the through-hole substrate 40.

[0030] As the above copper sintered body forming step, for example, as shown in FIG. 1(b), a copper paste 3 containing copper particles is applied to the through-hole substrate 40, the copper paste 3 is filled into the through holes 30, and a layer of the copper paste 3 can also be provided on both main surfaces of the through-hole substrate 40. Details of the copper paste 3 will be described later.

[0031] Examples of the method of applying the copper paste 3 to the through-hole substrate 40 include screen printing, transfer printing, offset printing, jet printing method, dispenser, jet dispenser, needle dispenser, comma coater, slit coater, die coater, gravure coater, slit coat, relief printing, intaglio printing, gravure printing, stencil printing, soft lithography, bar coater, applicator, particle deposition method, spray coater, spin coater, dip coater, etc.

[0032] When the copper paste is also applied on the main surface of the through-hole substrate, the thickness of the copper paste layer may be 1 μm or more, 2 μm or more, 3 μm or more, 5 μm or more, 10 μm or more, 15 μm or more, or 20 μm or more, and may be 3000 μm or less, 1000 μm or less, 500 μm or less, 300 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, or 100 μm or less.

[0033] The copper paste 3 may be appropriately dried from the viewpoint of suppressing the flow of copper particles during sintering of the copper paste 3 and the generation of voids in the copper sintered body. When drying the copper paste 3, the drying atmosphere may be an oxygen-free atmosphere such as nitrogen and rare gas, or a reducing atmosphere such as hydrogen and formic acid.

[0034] The drying method may be drying by leaving at room temperature, drying by heating, or drying under reduced pressure. For drying by heating or drying under reduced pressure, for example, a hot plate, a hot air dryer, a hot air heating furnace, a nitrogen dryer, an infrared dryer, an infrared heating furnace, a far-infrared heating furnace, a microwave heating device, a laser heating device, an electromagnetic heating device, a heater heating device, a steam heating furnace, a hot plate press device, etc. can be used. The drying temperature and time may be appropriately adjusted according to the type and amount of the dispersion medium used. The drying temperature may be, for example, 50 °C or more and 180 °C or less. The drying time may be, for example, 1 minute or more and 120 minutes or less.

[0035] After the copper paste filling step, the copper paste 3 is fired to sinter the copper particles contained in the copper paste 3. Thus, as shown in Fig. 2(a), a copper sintered body-filled through-hole substrate 50 in which a copper sintered body 5 including a porous 4, that is, having a porous structure, fills the through-hole 30 is obtained. In the present embodiment, a copper sintered body-filled through-hole substrate 50 in which the copper sintered bodies 5 are also provided on both main surfaces of the through-hole substrate 40 is obtained. Details of the copper sintered body 5 to be formed will be described later.

[0036] Firing can be carried out by heat treatment. For heat treatment, for example, heating means such as a hot plate, a hot air dryer, a hot air heating furnace, a nitrogen dryer, an infrared dryer, an infrared heating furnace, a far-infrared heating furnace, a microwave heating device, a laser heating device, an electromagnetic heating device, a heater heating device, a steam heating furnace, etc. can be used.

[0037] From the viewpoint of suppressing oxidation of the copper sintered body, an oxygen-free atmosphere is preferable for the atmosphere during firing, and a reducing atmosphere is more preferable from the viewpoint of removing the surface oxide of the copper particles in the copper paste 3. Examples of the oxygen-free atmosphere include introduction of an oxygen-free gas such as nitrogen or a rare gas, or under vacuum. Examples of the reducing atmosphere include in pure hydrogen gas, in a mixed gas of hydrogen and nitrogen typified by forming gas, in nitrogen containing formic acid gas, in a mixed gas of hydrogen and a rare gas, in a rare gas containing formic acid gas, etc. When heating without applying pressure as described later to sinter the copper paste 3, it is preferably in pure hydrogen gas or in a mixed gas of hydrogen and nitrogen typified by forming gas, and more preferably in pure hydrogen gas. By heating in pure hydrogen gas, it becomes possible to lower the sintering temperature of the copper particles. When using pure hydrogen gas, even if the thickness of the substrate is as thick as 500 μm and the diameter of the through hole 30 is as small as 20 μm, the gas reaches the central part of the through hole 30, and it becomes easy to obtain the copper sintered body 5.

[0038] From the viewpoint of reducing thermal damage to each member and improving the yield, the maximum temperature reached during the heat treatment may be 150 °C or higher, and may be 350 °C or lower, 300 °C or lower, or 260 °C or lower. If the maximum temperature reached is 150 °C or higher, sintering tends to proceed sufficiently when the maximum temperature holding time is 60 minutes or less. From the viewpoint of volatilizing all of the dispersion medium and improving the yield, the maximum temperature holding time may be 1 minute or longer, and may be 60 minutes or less, 40 minutes or less, or 30 minutes or less.

[0039] The firing of the copper paste may be carried out under pressure. In this case, in an atmosphere containing pure hydrogen gas, the pressure may be 0.05 MPa or more, 0.1 MPa or more, or 0.3 MPa, and may be 20 MPa or less, 15 MPa or less, or 10 MPa or less. Also, in an atmosphere containing nitrogen gas, the pressure may be 1 MPa or more, or 3 MPa, and may be 20 MPa or less, 15 MPa or less, or 10 MPa or less.

[0040] By setting the pressure to 0.05 MPa or more when using pure hydrogen gas and 1 MPa or more when using nitrogen gas, it becomes easier to suppress the generation of voids in the copper sintered body 5 formed in the central portion of the through hole 30, and it is easier to obtain a copper sintered body having good conductivity. Also, by setting the pressure to the above lower limit value or more, when the through hole substrate has the metal film 2, it becomes easier to improve the bonding strength between the metal film 2 and the copper sintered body 5. Further, as shown in Fig. 1(b), when pressurizing by sandwiching the through hole substrate 40 provided with the copper paste layer from above and below with the pressure jig A, by setting the pressure applied to the pressure jig A to the above lower limit value or more, it becomes easier to smooth the surface of the copper sintered body formed on the main surface of the through hole substrate 40. When the surface of the copper sintered body is smooth, there is an advantage that it becomes easier to form fine wiring when forming wiring by etching or the like in a later process. The pressure jig A is not particularly limited, and it may be a commercially available one, or it can also be produced using a metal member having a flat portion. For example, a pressure jig having two or more of the above metal members can pressurize the through hole substrate by sandwiching the through hole substrate between the metal members arranged so that the flat portions face each other. The pressure jig A may have a mechanism for adjusting the pressure applied to the through hole substrate. As the pressure adjusting means, a spring or the like can be used.

[0041] If the pressure is 20 MPa or less, it becomes easier to suppress the warping of the through-hole substrate 40. The inventors of the present invention speculate the reason for such an effect as follows. First, when the pressure is increased, the sintering density of the copper paste (particularly, the density on the side in contact with the pressing jig A) increases, and it is considered that the thermal expansion coefficient of the formed copper sintered body approaches the thermal expansion coefficient of general copper at 25°C, which is 16.5 μm / (m·K). On the other hand, for example, the thermal expansion coefficient of silicon at 25°C is 2.6 μm / (m·K). Therefore, as the density of the copper sintered body increases, the difference in thermal expansion coefficient between the copper sintered body and silicon becomes larger, and it is considered that warping is more likely to occur. In the present embodiment, by setting the pressure to 20 MPa or less, as a result, the increase in the density of the copper sintered body is moderately suppressed, the difference in thermal expansion coefficient between the copper sintered body and silicon becomes smaller, and it is considered that warping is suppressed.

[0042] Also, if the pressure applied during firing is within the above range, since a special pressing device is not required, the yield can be maintained without sacrificing it, and void reduction, joint strength, and connection reliability can be further improved. Examples of the method of applying pressure to the through-hole substrate coated with the copper paste include a method of placing a weight, a method of applying pressure using a pressing device, and a method of applying pressure using a fixing jig for pressing.

[0043] From the viewpoint of reducing the volume resistivity of the copper sintered body 5, the porosity of the copper sintered body formed on the main surface of the through-hole substrate may be 15% by volume or less, 14% by volume or less, 12% by volume or less, or 9% by volume or less based on the total volume including the porous structure of the copper sintered body. Also, the porosity of the copper sintered body 5 may be 1% by volume or more, 3% by volume or more, or 5% by volume or more from the viewpoint of suppressing cracking and warping of the through-hole substrate 40.

[0044] Since the copper sintered body formed on the main surface of the through-hole substrate has the above-mentioned porous structure, it becomes possible to lower the thermal expansion coefficient, reduce the difference in thermal expansion coefficient from an insulating substrate such as a silicon substrate, and suppress cracking and warping of the insulating substrate.

[0045] From the perspective of reducing the volume resistivity of the copper sintered body 5, the porosity of the copper sintered body filled in the through holes may be 15% by volume or less, 14% by volume or less, 12% by volume or less, or 9% by volume or less based on the total volume including the porous structure of the copper sintered body. Further, the porosity of the copper sintered body 5 may be 1% by volume or more, 3% by volume or more, or 5% by volume or more from the perspective of reducing the volume resistivity of the copper sintered body 5.

[0046] Since the copper sintered body filled in the through holes has the above-mentioned porous structure, it is possible to suppress disconnection due to cracks in the copper sintered body after sintering.

[0047] Note that the porosity of the copper sintered body is calculated by the following procedure. (i) Expose the cross-section (cut surface in the thickness direction of the substrate) of the copper sintered body of the copper sintered body filled through-hole substrate by a focused ion beam. (ii) Take a cross-sectional image (range of 10 μm in the thickness direction of the substrate and 10 μm in the direction orthogonal to the thickness direction of the substrate) of the exposed cross-section with a scanning electron microscope. (iii) Binarize the obtained cross-sectional image so that the sintered copper portion and the porous portion are separated. (iv) From the binarized cross-sectional image, the ratio of the area of the porous portion to the total area of the cross-section of the copper sintered body is defined as the porosity of the copper sintered body. When calculating the porosity of the copper sintered body filled in the through holes, in the above (i), expose the cross-section of the central portion of the copper sintered body filled in the through holes. When calculating the porosity of the central portion of the copper sintered body filled in the through holes, observe a range of ±5 μm in the thickness direction of the substrate and ±5 μm in the direction orthogonal to the thickness direction of the substrate from the central portion of the copper sintered body filled in the through holes. When calculating the porosity of the copper sintered body formed on the main surface of the copper sintered body filled through-hole substrate, in the above (i), expose the cross-section of the copper sintered body on the main surface. When calculating the porosity of the copper sintered body formed on the main surface of the copper sintered body filled through-hole substrate, observe the region from the surface of the copper sintered body formed on the main surface to 5 μm. When calculating the porosity of the copper sintered body used for calculating the filling rate of the resin cured product in the conductor described below, the observation location of the copper sintered body can be appropriately set to be the same location as the observation location of the conductor.

[0048] Also, if the pressure applied during firing is within the above range, a special pressurizing device is not required, so the yield can be maintained without sacrificing it, and void reduction, joint strength, and connection reliability can be further improved. Examples of the method of applying pressure to the through-hole substrate coated with the copper paste include a method of placing a weight, a method of applying pressure using a pressurizing device, and a method of applying pressure using a fixing jig for pressurization.

[0049] The proportion of copper element among the elements excluding light elements in the elements constituting the copper sintered body may be 95% by mass or more, 97% by mass or more, 98% by mass or more, or 100% by mass. If the proportion of the copper element in the copper sintered body is within the above range, the formation of intermetallic compounds or the precipitation of foreign elements at the grain boundaries of metallic copper can be suppressed, the properties of the metallic copper constituting the copper sintered body tend to become stronger, and more excellent connection reliability can be easily obtained.

[0050] In the copper sintered body forming step, the copper paste may be heated and fired without being pressurized. In this case, the porosity of the copper sintered body formed on the main surface of the through-hole substrate tends to increase, and since the thermal expansion coefficient of the copper sintered body decreases, cracks and warping of the through-hole substrate are less likely to occur.

[0051] <Resin impregnation step> In this step, for example, by applying a curable resin composition to the copper sintered body-filled through-hole substrate 50 obtained through the copper sintered body forming step, the copper sintered body 5 can be impregnated with the curable resin composition. In the present embodiment, the curable resin composition is impregnated into the copper sintered body 5 filling the through-hole 30 and the copper sintered body 5 formed on both main surfaces of the through-hole substrate 40. It is preferable that the porous portion 4 of the copper sintered body 5 is sufficiently filled with the impregnated curable resin composition.

[0052] (Thermosetting resin composition) Examples of the components constituting the thermosetting resin composition include thermosetting compounds. Examples of the thermosetting compounds include oxetane compounds, epoxy compounds, episulfide compounds, (meth)acrylic compounds, phenol compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds, and polyimide compounds. Among them, an epoxy compound may be used in view of further improving the curability and viscosity of the thermosetting resin composition and improving the properties and insulation reliability during high-temperature storage.

[0053] The thermosetting resin composition may further contain a thermosetting agent. Examples of the thermosetting agent include imidazole curing agents, amine curing agents, phenol curing agents, polythiol curing agents, acid anhydrides, thermal cation initiators, and thermal radical generators. These may be used alone or in combination of two or more. Among them, imidazole curing agents, polythiol curing agents, or amine curing agents are preferable in that they can be cured rapidly at low temperatures. Also, latent curing agents are preferable from the viewpoint of high storage stability when the thermosetting compound and the thermosetting agent are mixed. The latent curing agent is preferably a latent imidazole curing agent, a latent polythiol curing agent, or a latent amine curing agent. Note that the above thermosetting agent may be coated with a polymer substance such as a polyurethane resin or a polyester resin.

[0054] The imidazole curing agent is not particularly limited, and examples thereof include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, and 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct.

[0055] The above-mentioned polythiol curing agent is not particularly limited, and examples thereof include trimethylolpropane tris-3-mercaptopropionate, pentaerythritol tetrakis-3-mercaptopropionate, dipentaerythritol hexa-3-mercaptopropionate, and the like. The solubility parameter of the polythiol curing agent is preferably 9.5 or more, and preferably 12 or less. The above solubility parameter is calculated by the Fedors method. For example, the solubility parameter of trimethylolpropane tris-3-mercaptopropionate is 9.6, and the solubility parameter of dipentaerythritol hexa-3-mercaptopropionate is 11.4.

[0056] The above-mentioned amine curing agent is not particularly limited, and examples thereof include hexamethylenediamine, octamethylenediamine, decamethylenediamine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraspiro[5.5]undecane, bis(4-aminocyclohexyl)methane, metaphenylenediamine, and diaminodiphenyl sulfone.

[0057] The above-mentioned thermal cationic curing agent includes iodonium-based cationic curing agents, oxonium-based cationic curing agents, sulfonium-based cationic curing agents, and the like. Examples of the above-mentioned iodonium-based cationic curing agent include bis(4-tert-butylphenyl)iodonium hexafluorophosphate. Examples of the above-mentioned oxonium-based cationic curing agent include trimethyloxonium tetrafluoroborate. Examples of the above-mentioned sulfonium-based cationic curing agent include tri-p-tolylsulfonium hexafluorophosphate.

[0058] The above-mentioned thermal radical generator is not particularly limited, and examples thereof include azo compounds and organic peroxides. Examples of the above-mentioned azo compound include azobisisobutyronitrile (AIBN). Examples of the above-mentioned organic peroxide include di-tert-butyl peroxide and methyl ethyl ketone peroxide.

[0059] The application method of the curable resin composition includes methods such as screen printing, transfer printing, offset printing, jet printing method, dispenser, jet dispenser, needle dispenser, comma coater, slit coater, die coater, gravure coater, slit coating, letterpress printing, intaglio printing, gravure printing, stencil printing, soft lithography, bar coating, applicator, particle deposition method, spray coater, spin coater, dip coater, etc.

[0060] The curable resin composition may be applied on one main surface of the copper sintered body filled through-hole substrate 50, or may be applied on a part of the main surface. When applying the resin composition on both sides of the copper sintered body filled through-hole substrate 50, the resin composition is applied on one main surface of the copper sintered body filled through-hole substrate 50, and the resin composition is allowed to penetrate to the main surface side where the resin composition is not applied on the copper sintered body filled through-hole substrate 50, and then, the resin composition may be applied on the main surface where the resin composition was not applied. Thereby, the resin composition can be evenly distributed in the porous 4.

[0061] By leaving the copper sintered body filled through-hole substrate 50 coated with the curable resin composition in a reduced-pressure environment, the impregnation property of the curable resin composition into the porous 4 of the copper sintered body 5 can be improved.

[0062] In the resin impregnation step, it is preferable to impregnate the copper sintered body with the cured resin composition so that the filling rate of the resin cured product in the conductor formed through the resin curing step falls within a preferable range described later.

[0063] <Resin curing step> In this step, as shown in Fig. 2(d), by curing the curable resin composition (the curable resin composition filled in the porous body 4) impregnated in the copper sintered body 5, a conductor 35 is formed which includes the copper sintered body 5 filled with the resin cured product 6 in the porous body 4, and a conductor-filled through-hole substrate 51 in which at least the through-hole 30 is filled with the conductor 35 can be obtained. In the case of this embodiment, conductors 35 which include the copper sintered body 5 filled with the resin cured product 6 in the porous body 4 are also provided on both main surfaces of the through-hole substrate 40.

[0064] Curing of the curable resin composition can be performed by heat treatment. As the heat treatment, heating means such as a hot plate, a hot air dryer, a hot air heating furnace, a nitrogen dryer, an infrared dryer, an infrared heating furnace, a far-infrared heating furnace, a microwave heating device, a laser heating device, an electromagnetic heating device, a heater heating device, and a steam heating furnace can be used.

[0065] The atmosphere in the resin curing step may be an oxygen-free atmosphere from the viewpoint of suppressing oxidation of the copper sintered body 5, or may be a reducing atmosphere from the viewpoint of removing the surface oxide of the copper sintered body 5. Examples of the oxygen-free atmosphere include introduction of an oxygen-free gas such as nitrogen or a rare gas, or under vacuum. Examples of the reducing atmosphere include in pure hydrogen gas, in a mixed gas of hydrogen and nitrogen typified by forming gas, in nitrogen containing formic acid gas, in a mixed gas of hydrogen and a rare gas, and in a rare gas containing formic acid gas.

[0066] The maximum temperature reached during the heat treatment in the resin curing step may be 150°C or higher, 350°C or lower, 300°C or lower, or 260°C or lower from the viewpoints of reducing thermal damage to each member and improving the yield. If the maximum temperature reached is 150°C or higher, the curing of the resin composition tends to proceed sufficiently when the maximum temperature holding time is 60 minutes or less.

[0067] The conductor 35 (the conductor before the conductor removal step) formed in the resin curing step may be such that the filling rate of the resin cured product 6 satisfies the following conditions. (Conductor of the through-hole) (a) In the region from the center C of the through-hole 30 (the center in the hole length L and the center in the hole diameter D there) to a depth of 10 μm from the point S1 where the line L1 extending in the thickness direction of the substrate intersects the surface of the conductor 35, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body. (b) In the region from the point S1 to a depth of 10 - 20 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body. (c) In the region from the point S1 to a depth of 20 - 30 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body. (d) In the range of ±5 μm in the thickness direction of the substrate and ±5 μm in the direction orthogonal to the thickness direction of the substrate from the center C of the through-hole 30, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body.

[0068] (Conductor on the main surface of the substrate) (e) In the region from the surface S2 of the conductor 35 formed on the main surface of the substrate to a depth of 5 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body 5. (f) In the region from the surface S2 of the conductor 35 formed on the main surface of the substrate to a depth of 10 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body 5. (g) In the region from the surface S2 to a depth of 10 - 20 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body. (h) In the region at a depth of 20 to 30 μm from the surface S2, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body.

[0069] The filling rate of the cured resin 6 in the conductor 35 is calculated by the following procedure. (i) Expose the cross-section (the cut surface in the thickness direction of the substrate) of the conductor of the conductor-filled through-hole substrate by a focused ion beam. (ii) Take a cross-sectional image (a range of 10 μm in the thickness direction of the substrate and 10 μm in the direction orthogonal to the thickness direction of the substrate) of the exposed cross-section with a scanning electron microscope. (iii) Binarize the obtained cross-sectional image so that the sintered copper portion, the cured resin portion, and the porous portion not filled with the cured resin are separated. (iv) From the binarized cross-sectional image, obtain the ratio of the area of the porous portion not filled with the cured resin to the total area of the conductor cross-section, and define this as the porosity of the conductor. (v) Substitute the porosity of the copper sintered body before impregnating with the curable resin composition and the porosity of the conductor into the following formula (1) to calculate the filling rate of the cured resin in the conductor. Filling rate of cured resin in conductor (%) = [(B - A) / B] × 100 ··· Formula (1) [In Formula (1), A represents the porosity (%) of the conductor, and B represents the porosity (%) of the copper sintered body.] When calculating the porosity of the conductor filled in the through-hole, in the above (i), expose the cross-section of the central portion of the conductor in the through-hole. When calculating the porosity of the conductor formed on the main surface of the conductor-filled through-hole substrate, in the above (i), expose the cross-section of the conductor on the main surface.

[0070] <Conductor removal process> In this step, at least a part of the conductor 35 formed on the main surface of the through-hole substrate 40 can be removed. Examples of the means for removing the conductor include chemical polishing, mechanical polishing, chemical mechanical polishing, fly cut treatment, and plasma treatment. The fly cut treatment means cutting and flattening by a surface planer.

[0071] In the present embodiment, from the viewpoint of easy application by a general method, it is preferable that the removing means is one or more selected from the group consisting of etching, mechanical polishing, and chemical mechanical polishing, but it is not limited thereto.

[0072] By providing the conductor removing step, the manufacturing method of the conductor-filled through-hole substrate of the present embodiment makes the surface of the conductor 35 formed on the main surface of the through-hole substrate 40 flat, for example, and facilitates the formation of wiring.

[0073] In the present embodiment, the filling rate of the cured resin 6 in the conductor 35 after the conductor removing step may satisfy the following conditions. The filling rate can be calculated in the same manner as described above. (Conductor of through-hole) (a) In the region from the point S3 where the line L1 extending in the thickness direction of the substrate and passing through the central portion C of the through-hole 30 (the center in the hole length L and the center in the hole diameter D there) intersects the surface of the conductor 35 to a depth of 10 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body. (b) In the region from the point S3 to a depth of 10 to 20 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body. (c) In the region from the point S3 to a depth of 20 to 30 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body. (d) From the central part C of the through-hole 30, within a range of ±5 μm in the thickness direction of the substrate and ±5 μm in the direction orthogonal to the thickness direction of the substrate, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body. (Conductor on the main surface of the substrate) (e) In the region from the surface S4 of the conductor 35 formed on the main surface of the substrate to a depth of 5 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the internal spaces of the pores 4 of the copper sintered body 5. (f) In the region from the surface S4 of the conductor 35 formed on the main surface of the substrate to a depth of 10 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the internal spaces of the pores 4 of the copper sintered body 5. (g) In the region from a depth of 10 to 20 μm from the surface S4, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the internal spaces of the pores of the copper sintered body. (h) In the region from a depth of 20 to 30 μm from the surface S4, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the internal spaces of the pores of the copper sintered body.

[0074] The method for manufacturing a conductor-filled through-hole substrate according to this embodiment may further include a wiring formation step. The wiring formation step may include a resist formation step, an etching step, and a resist removal step, which will be described below.

[0075] <Resist formation step> In the resist formation step, as shown in FIG. 3(f), an etching resist 8 is formed on the conductor 35 formed on the main surface of the through-hole substrate 40.

[0076] As a method for forming the etching resist 8, for example, there are a method of silk-screen printing resist ink, or a method of laminating a negative-type photosensitive dry film for an etching resist on the copper foil, overlaying a photomask that transmits light in the wiring shape thereon, exposing it to ultraviolet light, and removing the unexposed portions with a developer, etc.

[0077] <Etching process> In the etching process, as shown in FIG. 4(g), the conductor 35 in the portion not covered by the etching resist 8 is removed by etching. In this embodiment, a part of the metal film 2 provided on both main surfaces of the insulating substrate 1 is removed by etching.

[0078] As a method of etching, for example, there are methods using chemical etching solutions used for ordinary wiring boards such as a solution of cupric chloride and hydrochloric acid, a ferric chloride solution, a solution of sulfuric acid and hydrogen peroxide, an ammonium persulfate solution, etc.

[0079] <Resist removal process> In the resist removal process, the etching resist 8 formed on the conductor 35 is removed.

[0080] The method for manufacturing a through-hole substrate according to this embodiment further includes a wiring formation process having the above steps, whereby a wiring 9 including a conductor 35 can be formed on the main surface of the through-hole substrate 40.

[0081] (Conductor-filled through-hole substrate) FIG. 4(h) is a cross-sectional view showing an embodiment of a conductor-filled through-hole substrate that can be manufactured by the method according to the above-described embodiment. The conductor-filled through-hole substrate 52 shown in FIG. 4(h) includes an insulating substrate 1 provided with a through-hole 30, a through-hole substrate 40 having through-holes 30 communicating with both main surfaces, and a conductor 35 filling the through-hole 30, and the conductor 35 includes a copper sintered body 5 having a porous structure and a cured resin 6 filled in the pores 4 of the copper sintered body 5.

[0082] The conductor-filled through-hole substrate 52 shown in Fig. 4(h) has a metal film 2 provided on both main surfaces of the insulating substrate 1 and on the wall surface of the through-hole. However, the metal film 2 may not be provided on the main surface, may be provided only on one main surface, or may not be provided on the wall surface of the through-hole. Further, the conductor-filled through-hole substrate 52 has wirings 9 including a metal film 2 and a conductor 35 provided on both main surfaces of the through-hole substrate 40, but the wirings 9 may be provided on one main surface of the through-hole substrate 40.

[0083] The conductor-filled through-hole substrate 52 may be such that the filling rate of the cured resin 6 in the conductor 35 satisfies the following conditions. The filling rate can be calculated in the same manner as described above. (Conductor in the through-hole) (a) In the region from the point S5 where a line L1 passing through the central portion C (the center in the hole length L and the center in the hole diameter D at that point) of the through-hole 30 and extending in the thickness direction of the substrate intersects the surface of the conductor 35 to a depth of 10 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body. (b) In the region from the point S5 to a depth of 10 to 20 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body. (c) In the region from the point S5 to a depth of 20 to 30 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body. (d) In the range of ±5 μm in the thickness direction of the substrate and ±5 μm in the direction orthogonal to the thickness direction of the substrate from the central portion C of the through-hole 30, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body. (Conductor on the main surface of the substrate) (e) In a region from the surface S6 of the conductor 35 formed on the main surface of the substrate to a depth of 5 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the internal spaces of the pores 4 of the copper sintered body 5. (f) In a region from the surface S6 of the conductor 35 formed on the main surface of the substrate to a depth of 10 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the internal spaces of the pores 4 of the copper sintered body 5. (g) In a region from a depth of 10 to 20 μm from the surface S6, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the internal spaces of the pores of the copper sintered body. (h) In a region from a depth of 20 to 30 μm from the surface S6, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the internal spaces of the pores of the copper sintered body.

[0084] (Semiconductor device) A semiconductor device manufactured using the conductor-filled through-hole substrate of this embodiment will be specifically described with reference to FIG. 5. FIG. 5 is a schematic cross-sectional view showing an embodiment of the semiconductor device of the present invention, and is a semiconductor device using TSV (Through-Silicon-Via) technology. In the semiconductor device 100 shown in FIG. 5(a), the wiring 27 on the interposer substrate 25 and the conductor 35 of the conductor-filled through-hole substrate 51 are directly connected, so that the interposer substrate 25 and the conductor-filled through-hole substrate 51 are flip-chip connected. The void between the interposer substrate 25 and the conductor-filled through-hole substrate 51 is filled without gaps with a cured adhesive 20 and is sealed. On the main surface of the conductor-filled through-hole substrate 51 opposite to the interposer substrate 25, the conductor-filled through-hole substrates 51 are repeatedly stacked. The conductor-filled through-hole substrates 51 are connected by conductors 35. The void between the conductor-filled through-hole substrates 51 is filled without gaps with a cured adhesive 20 and is sealed.

[0085] The semiconductor device 100 may be obtained, for example, by the following method. That is, the conductor-filled through-hole substrate 51 is laminated via an adhesive to obtain a laminate. The adhesive may be cured during lamination. By pressing the obtained laminate and the interposer substrate 25, they are electrically connected to form a connection body in which the laminate and the interposer substrate 25 are electrically connected. A dicing tape is attached to the surface of the formed connection body opposite to the surface on which the interposer substrate 25 is provided, and dicing is performed along the dicing line to obtain the semiconductor device 100.

[0086] In the semiconductor device 200 shown in FIG. 5(b), the wiring 27 on the interposer substrate 25 and the conductor 35 of the conductor-filled through-hole substrate 51 are connected via the fine bumps 15, so that the interposer substrate 25 and the conductor-filled through-hole substrate 51 are flip-chip connected. The void between the interposer substrate 25 and the conductor-filled through-hole substrate 51 is filled without a gap with the cured product 20 of the adhesive and is sealed. On the main surface of the conductor-filled through-hole substrate 51 opposite to the interposer substrate 25, the conductor-filled through-hole substrates 51 are repeatedly laminated via the fine bumps 15. The void between the conductor-filled through-hole substrates 51 is filled without a gap with the cured product 20 of the adhesive and is sealed.

[0087] The semiconductor device 200 may be obtained, for example, by the following method. That is, the conductor-filled through-hole substrate 51 provided with the fine bumps 15 on one main surface is laminated via an adhesive to obtain a laminate. The adhesive may be cured during lamination. By pressing the obtained laminate and the interposer substrate 25, they are electrically connected to form a connection body in which the laminate and the interposer substrate 25 are electrically connected. A dicing tape is attached to the surface of the formed connection body opposite to the surface on which the interposer substrate 25 is provided, and dicing is performed along the dicing line to obtain the semiconductor device 200.

[0088] The semiconductor device 100 or 200 may be such that the filling rate of the cured resin 6 in the conductor 35 satisfies the following conditions. Note that the filling rate can be calculated in the same manner as described above. (Conductor in through-hole) (A) In the range of ±5 μm in the thickness direction of the substrate and ±5 μm in the direction orthogonal to the thickness direction of the substrate from the central portion C of the through-hole 30, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body. (B) In the region from the point S7 where the line L1 extending in the thickness direction of the substrate and passing through the central portion C (the center in the hole length L and the center in the hole diameter D there) of the through-hole 30 intersects the surface S10 including the main surface of the insulating substrate to a depth of 10 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body. (C) In the region from the point S7 to a depth of 10 to 20 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body. (D) In the region from the point S7 to a depth of 20 to 30 μm, the filling rate of the cured resin may be 80% by volume or more, 90% by volume or more, or 95% by volume or more based on the total volume of the porous internal spaces of the copper sintered body.

[0089] (Copper paste) The copper paste containing copper particles used in the method for manufacturing the conductor-filled through-hole substrate of the present embodiment will be described.

[0090] The copper paste may contain, as copper particles, for example, first copper particles having a particle size (maximum diameter) of 0.8 μm or more.

[0091] The particle size (maximum diameter) of the first copper particles may be 1.2 μm or more. The particle size (maximum diameter) of the first copper particles may be 10 μm or less, or may be 8.0 μm or less.

[0092] The average particle size (average maximum diameter) of the first copper particles contained in the copper paste may be 0.5 μm or more, 0.8 μm or more, or 1.2 μm or more, and may be 20 μm or less, 10 μm or less, or 8 μm or less, from the viewpoint of improving the sintering density in the through holes and suppressing the occurrence of voids in the through holes.

[0093] The particle size (maximum diameter) and average particle size (average maximum diameter) of the first copper particles can be obtained, for example, from an SEM image of the particles. A method for calculating the particle size (maximum diameter) of the first copper particles from an SEM image is exemplified. A powder of the first copper particles is placed on a carbon tape for SEM with a spatula to prepare a sample for SEM. This sample for SEM is observed at 5000 times magnification with an SEM device. A rectangle circumscribing the first copper particle in the SEM image is drawn with image processing software, and the long side of the rectangle is taken as the particle size (maximum diameter) of the particle. This measurement is performed on 50 or more first copper particles using multiple SEM images, and the average particle size (average maximum diameter) is calculated.

[0094] The shape of the first copper particles may be, for example, spherical, lump-like, needle-like, flat (flake-like), approximately spherical, etc. The first copper particles may be an aggregate of copper particles having these shapes.

[0095] The first copper particles are preferably flat (flake-like) with an aspect ratio (long diameter / thickness) of 4 or more. In this case, the first copper particles are oriented approximately parallel to the surface of the copper paste applied, which suppresses volumetric shrinkage when the copper particles in the copper paste are sintered, making it easier to suppress voids occurring in the through-holes. In addition, by suppressing volumetric shrinkage when the copper particles in the copper paste are sintered, it is possible to suppress cracks in the copper sintered body formed on at least one of the main surfaces of the through-hole board.

[0096] The aspect ratio of the first copper particles is preferably 4 or more, more preferably 5 or more, and even more preferably 6 or more. If the aspect ratio is within the above range, the first copper particles in the copper paste are likely to be oriented parallel to the coating surface of the copper paste, and the volume shrinkage when sintering the copper particles in the copper paste can be suppressed. Thereby, when forming a wiring from a conductor provided on the main surface of the through-hole substrate, disconnection due to the thermal stress of the wiring can be further suppressed. In addition, the adhesion between the copper sintered body and the metal film formed on the insulating substrate can be improved. The aspect ratio (major axis / minor axis) of the copper particles in the copper paste can be determined, for example, by observing the SEM image of the particles and measuring the major axis and the minor axis.

[0097] The copper paste preferably contains first copper particles having a particle size (maximum diameter) of 0.8 μm or more and 10 μm or less and an aspect ratio of 4 or more. By the copper paste containing such first copper particles, the volume shrinkage when sintering the copper particles in the copper paste can be sufficiently reduced, and it becomes easy to form a copper sintered body having a porous structure and a sufficiently formed conductive network in the through-hole. Thereby, generation of voids in the through-hole can be suppressed, and a copper sintered body in which cracks are less likely to occur on the main surface of the through-hole substrate can be formed. When forming a wiring from a conductor containing this copper sintered body, disconnection due to the thermal stress of the wiring can be further suppressed.

[0098] The copper paste may contain copper particles having a particle size (maximum diameter) of 0.8 μm or more and 10 μm or less and an aspect ratio of less than 2. However, the content of the copper particles having a particle size (maximum diameter) of 0.8 μm or more and 10 μm or less and an aspect ratio of less than 2 is 50 parts by mass or less, 30 parts by mass or less, 20 parts by mass or less, 10 parts by mass or less, or 0 parts by mass with respect to 100 parts by mass of the first copper particles having a particle size (maximum diameter) of 0.8 μm or more and 10 μm or less and an aspect ratio of 4 or more. By restricting the content of the copper particles having a particle size (maximum diameter) of 0.8 μm or more and 10 μm or less and an aspect ratio of less than 2, it is possible to suppress the generation of voids in the through holes by the first copper particles in the copper paste, and to form a copper sintered body having a porous structure while sufficiently forming a conductive network in the through holes. Further, on the main surface of the through-hole substrate, the first copper particles are likely to be oriented substantially parallel to the coating surface of the copper paste, and it is possible to form a copper sintered body in which cracks are less likely to occur by more effectively suppressing volume shrinkage. When wiring is formed from a conductor including this copper sintered body, disconnection due to the thermal stress of the wiring can be further suppressed.

[0099] The content of the first copper particles in the copper paste may be 15% by mass or more, 20% by mass or more, or 50% by mass or more, and 85% by mass or less, 70% by mass or less, or 50% by mass or less, based on the total mass of the metal particles contained in the copper paste. If the content of the first copper particles is within the above range, the above-described effects can be more easily obtained.

[0100] The first copper particles may be treated with a surface treatment agent from the viewpoints of dispersion stability and oxidation resistance. The surface treatment agent may be one that is removed during wiring formation (when the copper particles are sintered). Examples of such surface treatment agents include aliphatic carboxylic acids such as palmitic acid, stearic acid, arachidic acid, and oleic acid; aromatic carboxylic acids such as terephthalic acid, pyromellitic acid, and o-phenoxybenzoic acid; aliphatic alcohols such as cetyl alcohol, stearyl alcohol, isobornyl cyclohexanol, and tetraethylene glycol; aromatic alcohols such as p-phenylphenol; alkylamines such as octylamine, dodecylamine, and stearylamine; aliphatic nitriles such as stearonitrile and decanenitrile; silane coupling agents such as alkylalkoxysilane; and polymer treatment agents such as polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, and silicone oligomer. The surface treatment agent may be used alone or in combination of two or more kinds.

[0101] The treatment amount of the surface treatment agent may be an amount of one molecular layer or more on the particle surface. Such a treatment amount of the surface treatment agent varies depending on the specific surface area of the first copper particles, the molecular weight of the surface treatment agent, and the minimum covering area of the surface treatment agent. The treatment amount of the surface treatment agent is usually 0.001 mass% or more.

[0102] The treatment amount of the surface treatment agent is related to the number of molecular layers (n) attached to the surface of the first copper particles, the specific surface area (A p )(unit: m 2 / g) of the first copper particles, the molecular weight (M s )(unit: g / mol) of the surface treatment agent, the minimum covering area (S S )(unit: m 2 / particle) of the surface treatment agent, and Avogadro's number (N A )(6.02×10 23 particles) and can be calculated therefrom. Specifically, the treatment amount of the surface treatment agent (mass%) = {(n·A p ·M s ) / (S S ·N A + n·A p ·M s)} is calculated according to the formula of × 100%.

[0103] The specific surface area of the first copper particles can be calculated by measuring the dried copper particles by the BET specific surface area measurement method. The minimum coating area of the surface treatment agent is 2.05 × 10 -19 m 2 / molecule when the surface treatment agent is a straight-chain saturated fatty acid. In the case of other surface treatment agents, it can be measured, for example, by calculation from a molecular model or by the method described in "Chemistry and Education" (Katsuhiro Ueda, Sumio Inafuku, Iwao Mori, 40(2), 1992, p114-117). An example of the method for quantifying the surface treatment agent is shown. The surface treatment agent can be identified by thermodesorption gas-gas chromatograph mass spectrometer of the dry powder obtained by removing the dispersion medium from the copper paste, and thereby the carbon number and molecular weight of the surface treatment agent can be determined. The carbon content ratio of the surface treatment agent can be analyzed by carbon analysis. Examples of the carbon analysis method include high-frequency induction heating furnace combustion / infrared absorption method. The amount of the surface treatment agent can be calculated by the above formula from the carbon number, molecular weight and carbon content ratio of the identified surface treatment agent.

[0104] As the first copper particles, commercially available ones can be used. Examples of commercially available first copper particles include MA-C025 (manufactured by Mitsui Mining & Smelting Co., Ltd., average particle size 4.1 μm), 3L3 (manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., average particle size 7.3 μm), 1110F (manufactured by Mitsui Mining & Smelting Co., Ltd., average particle size 5.8 μm), and 2L3 (manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., average particle size 9 μm).

[0105] In the production of the copper paste, first copper particles having a particle size (maximum diameter) of 0.8 μm or more and 10 μm or less and an aspect ratio of 4 or more are included, and the content of copper particles having a particle size (maximum diameter) of 0.8 μm or more and 10 μm or less and an aspect ratio of less than 2 is within the above-mentioned range. Commercially available products composed of such copper particles can be selected and used.

[0106] The ratio of the pore diameter of the through-hole to the particle diameter (maximum diameter) of the first copper particles [pore diameter (μm) / particle diameter (μm)] may be 4 or more, 8 or more, or 10 or more, and may be 150 or less, 100 or less, or 50 or less, from the viewpoint of suppressing volume shrinkage and forming a copper sintered body in which cracks are less likely to occur.

[0107] In one embodiment, the copper paste may contain the above-described first copper particles and second copper particles having a particle diameter (maximum diameter) of 0.5 μm or less. In this case, when the copper particles are sintered, the second copper particles are interposed between the first copper particles, and thus the conductivity of the resulting wiring tends to be improved. That is, it is preferable to use the first copper particles and the second copper particles in combination. When preparing a copper paste from only the second copper particles, since the volume shrinkage and sintering shrinkage associated with the drying of the dispersion medium are large, when sintering the copper particles, the sintered body is likely to peel off from the metal film provided on the insulating substrate, and it is difficult to obtain sufficient airtightness and connection reliability. However, by using the first copper particles and the second copper particles in combination, the volume shrinkage when sintering the copper paste is suppressed, and the adhesiveness between the copper sintered body formed in the through-hole and the metal film formed on the wall surface of the through-hole can be improved. As a result, breakage due to thermal stress of the copper sintered body in the through-hole becomes less likely to occur, and the airtightness and connection reliability against thermal stress are further improved.

[0108] The second copper particles can act as copper particles that suitably join between the first copper particles. Further, the second copper particles can have a function of promoting the sintering of the copper particles, being more excellent in sinterability than the first copper particles. For example, it becomes possible to sinter the copper particles at a lower temperature compared to the case where only the first copper particles are used. Also, when preparing a copper paste from only the second copper particles, since the volume shrinkage and sintering shrinkage associated with the drying of the dispersion medium are large, voids are likely to be generated inside the through-hole due to the volume shrinkage of the copper sintered body formed inside the through-hole. In particular, by using the flat first copper particles and the second copper particles in combination, the flat first copper particles act as copper particles that are suitably joined by the second copper particles, thereby suppressing the generation of voids inside the through-hole and facilitating the formation of a copper sintered body having a porous structure.

[0109] The average particle size (average maximum diameter) of the second copper particles contained in the copper paste may be 0.01 μm or more, 0.03 μm or more, 0.05 μm or more, 0.08 μm or more, 0.1 μm or more, or 0.2 μm or more, and may be 0.5 μm or less, 0.4 μm or less, 0.3 μm or less, or 0.2 μm or less.

[0110] If the average particle size (average maximum diameter) of the second copper particles is 0.01 μm or more, effects such as suppression of the synthesis cost of the second copper particles, good dispersibility, and suppression of the amount of surface treatment agent used are likely to be obtained. If the average particle size (average maximum diameter) of the second copper particles is 0.5 μm or less, an effect that the second copper particles are excellent in sinterability is likely to be obtained.

[0111] The second copper particles may contain 20% by mass or more of copper particles having a particle size (maximum diameter) of 0.01 μm or more and 0.5 μm or less. From the viewpoint of the sinterability of the copper paste, the second copper particles may contain 30% by mass or more, 50% by mass or more, and 85% by mass or less of copper particles having a particle size of 0.01 μm or more and 0.5 μm or less. When the content ratio of copper particles having a particle size (maximum diameter) of 0.01 μm or more and 0.5 μm or less in the second copper particles is 20% by mass or more, the dispersibility of the copper particles is further improved, and an increase in viscosity and a decrease in paste concentration can be further suppressed.

[0112] The content of the second copper particles in the copper paste may be 20% by mass or more, 30% by mass or more, 35% by mass or more, or 40% by mass or more based on the total mass of the metal particles contained in the copper paste, and may be 85% by mass or less, 80% by mass or less, or 75% by mass or less. If the content of the second copper particles is within the above range, while suppressing the generation of voids in the through hole, it becomes easy to form a copper sintered body having excellent adhesiveness to the metal film provided on the through hole substrate, and it is possible to form a copper sintered body in which cracks are unlikely to occur on the main surface of the through hole substrate. When wiring is formed from a conductor containing this copper sintered body, disconnection due to thermal stress of the wiring can be further suppressed.

[0113] The content of the second copper particles in the copper paste may be 20% by mass or more and 85% by mass or less based on the total mass of the first copper particles and the second copper particles. If the content of the second copper particles is 20% by mass or more, the space between the first copper particles can be sufficiently filled, and a copper sintered body in which cracks are less likely to occur can be formed. A wiring formed from a conductor including this copper sintered body is less likely to be disconnected due to thermal stress. If the content of the second copper particles is 85% by mass or less, the volume shrinkage when the copper particles are sintered can be sufficiently suppressed, so that the generation of voids in the through holes can be suppressed, and a copper sintered body in which cracks are less likely to occur can be formed. A wiring formed from a conductor including this copper sintered body is less likely to be disconnected due to thermal stress.

[0114] From the viewpoint of making it easier to obtain the above effects, the content of the second copper particles may be 20 parts by mass or more, 30% by mass or more, 35% by mass or more, or 40% by mass or more based on the total mass of the first copper particles and the second copper particles, and may be 85% by mass or less or 80% by mass or less.

[0115] The shape of the second copper particles may be, for example, spherical, massive, needle-like, flat (flake-like), substantially spherical, etc. The second copper particles may be an aggregate of copper particles having these shapes. From the viewpoints of dispersibility and fillability, the shape of the second copper particles may be spherical, substantially spherical, or flat (flake-like), and from the viewpoints of combustibility and miscibility with the first copper particles, etc., it may be spherical or substantially spherical.

[0116] From the viewpoints of dispersibility, fillability, and miscibility with the first copper particles, the aspect ratio of the second copper particles may be 5 or less, 4 or less, or 3 or less.

[0117] The second copper particles may be treated with a specific surface treatment agent. Examples of the specific surface treatment agent include organic acids having 8 to 16 carbon atoms. Examples of the organic acids having 8 to 16 carbon atoms include caprylic acid, methylheptanoic acid, ethylhexanoic acid, propylpentanoic acid, pelargonic acid, methyloctanoic acid, ethylheptanoic acid, propylhexanoic acid, capric acid, methylnonanoic acid, ethyloctanoic acid, propylheptanoic acid, butylhexanoic acid, undecanoic acid, methyldecanoic acid, ethyldecanoic acid, propyloctanoic acid, butylheptanoic acid, lauric acid, methylundecanoic acid, ethyldecanoic acid, propylnonanoic acid, butyloctanoic acid, pentylheptanoic acid, tridecanoic acid, methyldodecanoic acid, ethylundecanoic acid, propyldecanoic acid, butylnonanoic acid, pentyloctanoic acid, myristic acid, methyltridecanoic acid, ethyldodecanoic acid, propylundecanoic acid, butyldecanoic acid, pentylnonanoic acid, hexyl octanoic acid, pentadecanoic acid, methyltetradecanoic acid, ethyltridecanoic acid, propyldodecanoic acid, butylundecanoic acid, pentyl decanoic acid, hexylnonanoic acid, palmitic acid, methylpentadecanoic acid, ethyltetradecanoic acid, propyltridecanoic acid, butyldodecanoic acid, pentylundecanoic acid, hexyl decanoic acid, heptylnonanoic acid, methylcyclohexanecarboxylic acid, ethylcyclohexanecarboxylic acid, propylcyclohexanecarboxylic acid, butylcyclohexanecarboxylic acid, pentylcyclohexanecarboxylic acid, hexylcyclohexanecarboxylic acid, heptylcyclohexanecarboxylic acid, octylcyclohexanecarboxylic acid, nonylcyclohexanecarboxylic acid and other saturated fatty acids; unsaturated fatty acids such as octenoic acid, nonenoic acid, methylnonenoic acid, decenoic acid, undecenoic acid, dodecenoic acid, tridecenoic acid, tetradecenoic acid, myristoleic acid, pentadecenoic acid, hexadecenoic acid, palmitoleic acid, sabienic acid; aromatic carboxylic acids such as terephthalic acid, pyromellitic acid, o-phenoxybenzoic acid, methylbenzoic acid, ethylbenzoic acid, propylbenzoic acid, butylbenzoic acid, pentylbenzoic acid, hexylbenzoic acid, heptylbenzoic acid, octylbenzoic acid, nonylbenzoic acid. The organic acid may be used alone or in combination of two or more kinds.By combining such an organic acid with the second copper particles, it tends to be possible to achieve both the dispersibility of the second copper particles and the desorbability of the organic acid during sintering.

[0118] The treatment amount of the surface treatment agent may be an amount that adheres to one to three monolayers on the surface of the second copper particles. The treatment amount of the surface treatment agent may be 0.07% by mass or more, 0.10% by mass or more, or 0.2% by mass or more, and may be 2.1% by mass or less, 1.6% by mass or less, or 1.1% by mass or less. The surface treatment amount of the second copper particles can be calculated by the method described above for the first copper particles. The same applies to the specific surface area, the molecular weight of the surface treatment agent, and the minimum coating area of the surface treatment agent.

[0119] As the second copper particles, those synthesized or commercially available can be used.

[0120] The total content of the first copper particles and the second copper particles in the copper paste may be 90% by mass or more based on the total mass of the metal particles contained in the copper paste. If the total content of the first copper particles and the second copper particles is within the above range, it becomes easier to suppress the generation of voids in the through holes. From the viewpoint of more easily obtaining such an effect, the total content of the first copper particles and the second copper particles may be 95% by mass or more, or even 100% by mass based on the total mass of the metal particles.

[0121] The copper paste may further contain other metal particles other than copper particles. Examples of the other metal particles include particles such as nickel, silver, gold, palladium, and platinum. The average particle diameter (maximum diameter) of the other metal particles may be 0.01 μm or more or 0.05 μm or more, and may be 5 μm or less, 3.0 μm or less, or 2.0 μm or less. When other metal particles are included, the content may be less than 20% by mass, or may be 10% by mass or less based on the total mass of the metal particles contained in the copper paste from the viewpoint of obtaining sufficient bonding properties. Other metal particles may not be included. The shape of the other metal particles is not particularly limited.

[0122] The dispersion medium contained in the copper paste is not particularly limited and may be, for example, volatile. Examples of the volatile dispersion medium include monohydric and polyhydric alcohols such as pentanol, hexanol, heptanol, octanol, decanol, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, α-terpineol, isobornyl cyclohexanol (MTPH); ethers such as ethylene glycol butyl ether, ethylene glycol phenyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, diethylene glycol isobutyl ether, diethylene glycol hexyl ether, triethylene glycol methyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, diethylene glycol isopropyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol butyl methyl ether, propylene glycol propyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol propyl ether, dipropylene glycol butyl ether, dipropylene glycol dimethyl ether, tripropylene glycol methyl ether, tripropylene glycol dimethyl ether; esters such as ethylene glycol ethyl ether acetate, ethylene glycol butyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, dipropylene glycol methyl ether acetate (DPMA), ethyl lactate, butyl lactate, γ-butyrolactone, propylene carbonate; acid amides such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide; aliphatic hydrocarbons such as cyclohexane, octane, nonane, decane, undecane; aromatic hydrocarbons such as benzene, toluene, xylene; mercaptans having an alkyl group with 1 to 18 carbon atoms; and mercaptans having a cycloalkyl group with 5 to 7 carbon atoms.Examples of mercaptans having an alkyl group with 1 to 18 carbon atoms include ethyl mercaptan, n-propyl mercaptan, i-propyl mercaptan, n-butyl mercaptan, i-butyl mercaptan, t-butyl mercaptan, pentyl mercaptan, hexyl mercaptan, and dodecyl mercaptan. Examples of mercaptans having a cycloalkyl group with 5 to 7 carbon atoms include cyclopentyl mercaptan, cyclohexyl mercaptan, and cycloheptyl mercaptan.

[0123] The content of the dispersion medium may be 3 parts by mass or more, 4 parts by mass or more, or 5 parts by mass or more, and may be 20 parts by mass or less, 16 parts by mass or less, or 12 parts by mass or less, with the total mass of the metal particles contained in the copper paste being 100 parts by mass. If the content of the dispersion medium is within the above range, the copper paste can be adjusted to a more appropriate viscosity, and it is also easier to suppress the generation of voids in the through holes.

[0124] To the copper paste, wetting improvers such as nonionic surfactants and fluorosurfactants, defoamers such as silicone oil, and ion trappers such as inorganic ion exchangers may be appropriately added as needed.

[0125] The above-described copper paste can be prepared by mixing copper particles and optional components (additives, other metal particles, etc.) in a dispersion medium. After mixing each component, a stirring treatment may be performed. The maximum diameter of the dispersion may be adjusted by a classification operation.

[0126] The copper paste may be prepared by premixing the second copper particles, a surface treatment agent, and a dispersion medium, performing a dispersion treatment to prepare a dispersion of the second copper particles, and further mixing the first copper particles, other metal particles, and optional additives. By adopting such a procedure, the dispersibility of the second copper particles is improved, the miscibility with the first copper particles is enhanced, and the performance of the copper paste is further improved. Aggregates may be removed by subjecting the dispersion of the second copper particles to a classification operation.

Examples

[0127] The present invention will be described in more detail by way of examples below. However, the present invention is not limited to the following examples.

[0128] (Synthesis of second copper particles) [Synthesis of copper nonanoate] 150 mL of 1-propanol (Kanto Chemical Co., Inc., special grade) was added to 91.5 g (0.94 mol) of copper hydroxide (Kanto Chemical Co., Inc., special grade) and stirred, and 370.9 g (2.34 mol) of nonanoic acid (Kanto Chemical Co., Inc., 90% or more) was added thereto. The resulting mixture was heated and stirred in a separable flask at 90 °C for 30 minutes. The resulting solution was filtered while being heated to remove undissolved matter. Then, it was allowed to cool, and the resulting copper nonanoate was suction filtered and washed with hexane until the washing liquid became clear. The obtained powder was dried in an explosion-proof oven at 50 °C for 3 hours to obtain copper(II) nonanoate. The yield was 340 g (yield 96 mass%).

[0129] [Synthesis of second copper particles] 15.01 g (0.040 mol) of copper(II) nonanoate obtained above and 7.21 g (0.040 mol) of copper(II) acetate anhydride (Kanto Chemical Co., Inc., special grade) were placed in a separable flask, 22 mL of 1-propanol and 32.1 g (0.32 mol) of hexylamine (Tokyo Chemical Industry Co., Ltd., purity 99%) were added, and the mixture was heated and stirred in an oil bath at 80 °C until dissolved. It was transferred to an ice bath and cooled until the internal temperature reached 5 °C, and then 7.72 mL (0.16 mol) of hydrazine monohydrate (Kanto Chemical Co., Inc., special grade) was stirred in the ice bath. The molar ratio of copper to hexylamine is 1:4. Then, it was heated and stirred in an oil bath at 90 °C. At that time, a reduction reaction accompanied by foaming proceeded, and the reaction was completed within 30 minutes. The inner wall of the separable flask exhibited a copper luster, and the solution changed to dark red. Centrifugation was carried out at 9000 rpm (revolutions per minute) for 1 minute to obtain a solid. The step of further washing the solid with 15 mL of hexane was repeated 3 times to remove acid residues, and a powder of copper particles having a copper luster (second copper particles) was obtained.

[0130] The copper particles synthesized above were observed using a transmission electron microscope (manufactured by JEOL Ltd., product name: JEM-2100F). The average value of the major axis of 200 randomly selected copper particles was 104 nm. The shape of the second particles was spherical.

[0131] (Preparation of Copper Paste) <Examples 1 to 73> The following raw materials were mixed at the ratios shown in Tables 1 to 8 to prepare a copper paste.

[0132] [First Copper Particles] Flat 1.4 μm: 1100YP (manufactured by Mitsui Mining & Smelting Co., Ltd., average particle size 1.4 μm (D50), product name) Flat 3.1 μm: 1200YP (manufactured by Mitsui Mining & Smelting Co., Ltd., average particle size 3.1 μm (D50), product name) Flat 5.8 μm: MA-C05KP (manufactured by Mitsui Mining & Smelting Co., Ltd., average particle size 5.8 μm (D50), product name) Flat 7.3 μm: MA-C05KFD (manufactured by Mitsui Mining & Smelting Co., Ltd., average particle size 7.3 μm (D50), product name)

[0133] [Second Copper Particles] Spherical 100 nm: the copper particles synthesized above Spherical 250 nm: CH0200 (manufactured by Mitsui Mining & Smelting Co., Ltd., D50 250 nm, product name) [Others] Diethylene glycol (manufactured by Fujifilm Wako Pure Chemical Corporation)

[0134] <Comparative Example 1> 70 parts by mass of 1100YP (manufactured by Mitsui Mining & Smelting Co., Ltd., average particle size 1.4 μm (D50), trade name) as the first copper particles, 30 parts by mass of the copper particles synthesized above as the second copper particles, 5 parts by mass of diethylene glycol (manufactured by Fujifilm Wako Pure Chemical Corporation), and 5 parts by mass of a resin component were mixed to prepare a copper paste. As the resin component, a mixture of an acrylic resin as an organic binder and carbitol and terpineol as organic solvents (the mass ratio of carbitol to terpineol in the mixture is carbitol:terpineol = 1:1) was used in a mass ratio of 1:2.

[0135] (Preparation process of through-hole substrate) <Examples 1 to 73 and Comparative Example 1> A silicon substrate having through-holes and with a titanium layer, a nickel layer, and a copper layer formed in this order on both main surfaces and the wall surfaces of the through-holes was prepared as a through-hole substrate. The diameter of the silicon substrate was 6 inches and the thickness was 500 μm. The pore diameters of the through-holes of the silicon substrate are shown in Tables 1 to 8. The titanium layer, nickel layer, and copper layer were formed sequentially by sputtering.

[0136] (Copper sintered body formation process) <Examples 1 to 8, 12 to 21, 24 to 43, 48 to 73 and Comparative Example 1> The prepared copper paste was applied onto both main surfaces of the silicon substrate using a metal spatula, and the through-holes were filled with the copper paste. After application, the copper paste was dried in air at 90 °C for 10 minutes. After drying, a copper paste layer with a thickness of 30 μm was formed on the silicon substrate.

[0137] The silicon substrate with a copper paste layer formed thereon was pressed from both sides by a pressing jig. The pressure during pressing was adjusted so that the pressure applied to the silicon substrate was the pressure described in Tables 1 to 8. The pressing jig includes a flat aluminum plate and a spring, and the pressure during pressing can be adjusted. The silicon substrate pressed by the pressing jig was placed in a tube furnace (manufactured by ABC Co., Ltd.), and argon gas was flowed at 1 L / min to replace the air in the tube furnace with argon gas. Then, while flowing hydrogen gas at 300 mL / min, the temperature was raised for 10 minutes, and sintering treatment was performed under the conditions of 300 °C for 60 minutes to sinter the copper paste. Then, the argon gas was changed to 0.3 L / min for cooling, and it was taken out in the air at 50 °C or lower to obtain a copper sintered body-filled through-hole substrate. The thickness of the copper sintered body formed on both main surfaces of the sintered silicon substrate was 25 μm.

[0138] <Examples 9 to 11> A copper sintered body-filled through-hole substrate was obtained in the same manner as in Example 1, except that the silicon substrate was not pressed by the pressing jig. The thickness of the copper sintered body formed on both main surfaces of the sintered silicon substrate was 35 μm.

[0139] <Examples 22 and 23> A copper sintered body-filled through-hole substrate was obtained in the same manner as in Example 1, except that nitrogen gas was flowed instead of hydrogen gas during the sintering treatment. The thickness of the copper sintered body formed on both main surfaces of the sintered silicon substrate was 30 μm.

[0140] <Examples 44 to 47> A copper sintered body-filled through-hole substrate was obtained in the same manner as in Example 1, except that the temperature was raised for 10 minutes and sintering treatment was performed under the conditions of 225 °C for 60 minutes. The thickness of the copper sintered body formed on both main surfaces of the sintered silicon substrate was 30 μm.

[0141] (Measurement of Porosity of Copper Sintered Body) <Examples 1 to 73 and Comparative Example 1> Using a focused ion beam processing and observation apparatus (manufactured by Hitachi High-Technologies Corporation, product name: MI4050), the cross-section of the central part of the through-hole of the silicon substrate in the copper sintered body-filled through-hole substrate and the cross-section of the copper sintered body provided on the main surface of the silicon substrate were exposed by the focused ion beam, and the cross-section was observed. When observing the cross-section of the central part of the through-hole, a range of ±5 μm in the thickness direction of the silicon substrate and ±5 μm in the direction orthogonal to the thickness direction of the silicon substrate was observed from the central part of the copper sintered body filled in the through-hole. When observing the cross-section of the copper sintered body provided on the main surface of the silicon substrate, a range of 10 μm in the thickness direction of the silicon substrate and 10 μm in the direction orthogonal to the thickness direction of the silicon substrate was observed in the region from the surface of the copper sintered body formed on the main surface of the silicon substrate to 5 μm. For the observation, a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, product name: S-3700N) was used, the magnification was set to 10,000 times, and a cross-sectional image (about 10 μm square) of the copper sintered body was taken. Five observation points were set. The obtained cross-sectional image was binarized using image analysis software (Adobe Photoshop (registered trademark) Elements) so that the sintered copper part and the porous part were separated. The binarized cross-sectional image is shown in Fig. 6. For each of the five observation points, the ratio of the area of the porous part to the total area of the copper sintered body cross-section was defined as the porosity. The average value of the porosities of the five observations was defined as the porosity of the copper sintered body. The results are shown in Tables 1 to 8.

[0142] (Resin impregnation process) <Examples 1 to 73> The curable resin composition shown below was applied to one side of a copper-sintered body-filled through-hole substrate using a roll coater. Subsequently, the copper-sintered body-filled through-hole substrate was placed in a container, and the inside of the container was evacuated so that the gauge pressure became 100 KPa to create a vacuum state. The copper-sintered body-filled through-hole substrate was held in the vacuum state for 10 minutes, and then the copper-sintered body-filled through-hole substrate was taken out of the container. It was confirmed that the curable resin composition had impregnated the copper sintered body in the through holes and had reached the surface opposite to the surface where the curable resin composition was applied on the copper sintered body in the through holes. The curable resin composition remaining on the application surface of the curable resin composition on the copper-sintered body-filled through-hole substrate was removed with a rubber spatula. Next, the curable resin composition was applied to the surface opposite to the surface where the curable resin composition was applied using a roll coater, and the curable resin composition remaining on the surface of the copper-sintered body-filled through-hole substrate was removed as much as possible with a rubber spatula.

[0143] [Curable resin composition] YDF-170 (manufactured by Tokyo Chemical Industry Co., Ltd., trade name of bisphenol F type epoxy resin, epoxy equivalent = 170): 95 parts by mass 2PZ-CN (manufactured by Shikoku Chemicals Corporation, trade name of imidazole compound): 5 parts by mass

[0144] [Comparative Example 1] The resin impregnation step was not performed.

[0145] (Resin curing step) [Examples 1 to 73] The through-hole substrate in which the copper sintered body was impregnated with the curable resin composition was held at 180 °C for 1 hour in a nitrogen atmosphere to obtain a conductor-filled through-hole substrate.

[0146] [Comparative Example 1] The resin curing step was not performed.

[0147] (Conductor removal step) [Examples 1 to 73 and Comparative Example 1] Mechanical polishing was performed on both sides of the conductor-filled through-hole substrate until the thickness of the copper sintered body on both sides of the conductor-filled through-hole substrate reached 20 μm. As a sample stage for attaching the conductor-filled through-hole substrate, a ceramic jig (manufactured by Kennametal Japan Co., Ltd.) was used, and as a material for attaching the conductor-filled through-hole substrate to the sample stage, Alkowax (manufactured by Nippon Seiko K.K.) was used. Also, as polishing agents, DP-suspension P-3 μm·1 μm·1 / 4 μm (manufactured by Struers) were used in order.

[0148] [Filling ratio of resin cured product in conductor] <Examples 1 to 73 and Comparative Example 1> The conductor-filled through-hole substrate subjected to mechanical polishing was cut in the thickness direction, and the cross section at the center of the through-hole of the silicon substrate and the cross section of the conductor provided on the main surface of the silicon substrate were exposed by a focused ion beam, and these cross sections were observed. When observing the cross section at the center of the through-hole of the silicon substrate, a range of ±5 μm in the thickness direction of the silicon substrate and ±5 μm in the direction orthogonal to the thickness direction of the silicon substrate was observed from the center of the through-hole. When observing the cross section of the conductor provided on the main surface of the silicon substrate, a range of 10 μm in the thickness direction of the silicon substrate and 10 μm in the direction orthogonal to the thickness direction of the silicon substrate was observed in the region from the surface of the conductor provided on the main surface of the silicon substrate to 5 μm. A cluster ion beam processing observation apparatus (manufactured by Hitachi High-Technologies Corporation, product name: MI4050) was used. For observation, a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, product name: S-3700N) was used at a magnification of 10,000 times, and a cross-sectional image (approx. 10 μm square) of the conductor was taken. Five observation locations were set. The obtained cross-sectional images were binarized using image analysis software (Adobe Photoshop (registered trademark) Elements) so that the sintered copper part, the resin cured part, and the space in the porous part not filled with the resin cured part could be separated. For each of the five observation locations, the ratio of the area of the space in the porous part not filled with the resin cured part to the total area of the conductor cross-section was determined, and this was defined as the porosity. The average value of the porosities of the five observations was taken as the porosity of the conductor. By substituting the porosity of the copper sintered body and the porosity of the conductor into the following formula (1), the filling rate of the resin cured part in the conductor was calculated. Filling rate of resin cured part in conductor (%) = [(B - A) / B] × 100 ··· Formula (1) [In Formula (1), A represents the porosity (%) of the conductor, and B represents the porosity (%) of the copper sintered body.]

[0149] (Wiring formation process (resist formation, etching, and resist removal)) <Examples 1 to 73 and Comparative Example 1> A dry film H-W425 (product name, manufactured by Hitachi Chemical Co., Ltd.) for ultraviolet curable etching resist was pressure-bonded to the surfaces of the copper sintered bodies on both sides of the conductor-filled through-hole substrate that had undergone mechanical polishing treatment using a laminator. Then, the wiring pattern was exposed with a photomask, and after resist development - etching of the copper sintered body - resist removal, wiring was formed to obtain a conductor-filled through-hole substrate (test piece 55) shown in FIG. 7. In the obtained conductor-filled through-hole substrate (test piece 55), the conductor filled in the through-hole is electrically connected by the conductor (wiring) provided on the substrate surface.

[0150] (Initial resistance value) <Examples 1 to 73 and Comparative Example 1> The connection resistance value was measured as the initial resistance value of the conductor-filled through-hole substrate (test piece 55). When the pore diameter of the through-hole in the silicon substrate was 20 μm, the resistance value of 20 connected through-holes was measured. When the pore diameter of the through-hole in the silicon substrate was 30 μm, the resistance value of 30 connected through-holes was measured. When the pore diameter of the through-hole in the silicon substrate was 50 μm, the resistance value of 30 connected through-holes was measured. When the pore diameter of the through-hole in the silicon substrate was 100 μm, the resistance value of 100 connected through-holes was measured. When the pore diameter of the through-hole in the silicon substrate was 200 μm, the resistance value of 200 connected through-holes was measured respectively. The measured connection resistance values were evaluated according to the following criteria. Those with an evaluation of B or above were judged to be good. The results are shown in Tables 1 to 8. A: Resistance value is less than 10 mΩ B: Resistance value is 10 mΩ or more and less than 30 mΩ C: Resistance value is 30 mΩ or more and less than 100 mΩ D: Resistance value is 100 mΩ or more and less than 500 mΩ E: Resistance value is 500 mΩ or more

[0151] (Temperature cycle connectivity test) <Examples 1 to 73 and Comparative Example 1> The conductor-filled through-hole substrate (test piece 55) was set in a temperature cycle tester (TSA-72SE-W, manufactured by Espec Corporation), and the temperature cycle connection reliability test was carried out under the conditions of low temperature side: -40 °C, 15 minutes, room temperature: 2 minutes, high temperature side: 125 °C, 15 minutes, defrosting cycle: automatic, number of cycles: 50, 100, 300, 500 cycles. When the pore diameter of the through-hole in the silicon substrate was 20 μm, the resistance value of 20 connected through-holes was measured. When the pore diameter of the through-hole in the silicon substrate was 30 μm, the resistance value of 30 connected through-holes was measured. When the pore diameter of the through-hole in the silicon substrate was 50 μm, the resistance value of 30 connected through-holes was measured. When the pore diameter of the through-hole in the silicon substrate was 100 μm, the resistance value of 100 connected through-holes was measured. When the pore diameter of the through-hole in the silicon substrate was 200 μm, the resistance value of 200 connected through-holes was measured respectively. The measured connection resistance values were evaluated according to the following criteria. Those with an evaluation of B or above after 500 temperature cycle tests were judged to be good. The results are shown in Tables 1 to 8. A: The resistance change rate is less than 1% of the initial resistance value B: The resistance change rate is 1% or more and less than 3% of the initial resistance value C: The resistance change rate is 3% or more and less than 5% of the initial resistance value D: The resistance change rate is 5% or more and less than 10% of the initial resistance value E: The resistance change rate is 10% or more and less than 20% of the initial resistance value F: The resistance change rate is 20% or more of the initial resistance value

[0152] (Crack of the substrate) (Examples 1 to 73 and Comparative Example 1) The conductor-filled through-hole substrate (test piece 55) was visually inspected to check for cracks in the silicon substrate. The case without cracks was evaluated as ○, and the case with any cracks, even partially, was evaluated as ×. The results are shown in Tables 1 to 8.

[0153] (Airtightness) (Examples 1 to 73 and Comparative Example 1) The airtightness of the conductor-filled through-hole substrate (test piece 55) was evaluated. The evaluation was performed using a helium leak detector ("UL200" manufactured by LEYBOLD). Specifically, the conductor-filled through-hole substrate was set in a jig, evacuated until the inlet pressure of the measuring machine reached 5 Pa, and after applying He pressure (0.1 MPa) for 30 seconds when the inlet pressure reached 5 Pa, the leak rate was measured and evaluated according to the following criteria. The results are shown in Tables 1 to 8. A: The leak rate is less than 1×10 -11 Pa·m 3 / sec B: The leak rate is 1×10 -11 or more and less than 1×10 -10 Pa·m 3 / sec C: The leak rate is 1×10 -10 or more and less than 1×10 -9 Pa·m 3 / sec D: The leak rate is 1×10 -9 or more and less than 1×10 -8 Pa·m 3 / sec E: Leakage amount is 1×10 -8 or more and 1×10 -6 Pa·m 3 / sec or less F: Leakage amount is 1×10 -6 Pa·m 3 / sec or more.

[0154] (Adhesion of wiring - Pull strength -) <Examples 1 to 73 and Comparative Example 1> For the conductor-filled through-hole substrate obtained in the same manner except that a 2 mm × 2 mm wiring pattern was formed in the wiring formation process, a stud pin with a tip area of 1 mm 2 was vertically joined with solder to obtain a test piece. The test piece was fixed, the stud pin was gripped by the chuck part of a tensile testing machine, and pulled vertically upward at a rising speed of 50 mm / min, and the breaking load when the copper sintered body on the main surface of the silicon substrate was peeled off from the silicon substrate was measured. Then, the adhesion strength was calculated using the following formula from the measured value of the obtained breaking load and the breaking area of the copper sintered layer. The measured value was the average of 10 points and was evaluated according to the following criteria. The results are shown in Tables 1 to 8.

[0155] Adhesion strength (MPa) = Breaking load (kgf) / Breaking area (mm 2 ) × 9.8 (N / kgf). A: Adhesion strength (MPa) is 50 MPa or more B: Adhesion strength (MPa) is 40 MPa or more and less than 50 MPa C: Adhesion strength (MPa) is 30 MPa or more and less than 40 MPa D: Adhesion strength (MPa) is 20 MPa or more and less than 30 MPa E: Adhesion strength (MPa) is 5 MPa or more and less than 20 MPa F: Adhesion strength (MPa) is less than 5 MPa

[0156] (Wiring formability - Presence or absence of cracks -) <Examples 1 to 73 and Comparative Example 1> A conductor-filled through-hole substrate obtained in the same manner except that five 2 mm × 2 mm wiring patterns were formed in the wiring formation process was monitored with an optical microscope, and the presence or absence of cracks (length 0.5 mm or more) in the wiring patterns was monitored. The magnification was 500 times, and the evaluation was performed according to the following criteria. The results are shown in Tables 1 to 8. A: No crack occurred B: One or more but less than two cracks C: Two or more but less than five cracks D: Five or more but less than ten cracks E: Ten or more but less than twenty cracks F: Twenty or more cracks

[0157] (Volume resistivity) <Examples 1 to 73 and Comparative Example 1> The volume resistivity of the conductor formed on the silicon substrate was measured. The volume resistivity was calculated from the surface resistance value measured with a four-terminal probe surface resistance measuring instrument (manufactured by Mitsubishi Analytech Co., Ltd., product name: Loresta GP) and the film thickness obtained with a non-contact surface / layer cross-sectional shape measurement system (VertScan, Rhika System Co., Ltd.). The results are shown in Tables 1 to 8.

[0158]

Table 1

[0159]

Table 2

[0160]

Table 3

[0161]

Table 4

[0162]

Table 5

[0163]

Table 6

[0164]

Table 7

[0165]

Table 8

Explanation of Symbols

[0166] 1…Insulating substrate, 2…Metal film, 3…Copper paste, 4…Porous, 5…Copper sintered body, 6…Resin cured product, 8…Etching resist, 9…Wiring, 15…Fine bump, 20…Cured adhesive, 25…Interposer substrate, 27…Wiring, 30…Through hole, 35…Conductor, 40…Through hole substrate, 50…Through hole substrate filled with copper sintered body, 51, 52…Through hole substrate filled with conductor, 55…Test piece, 100, 200…Semiconductor device, A…Pressing jig

Claims

1. A preparation step of preparing a through-hole substrate including an insulating substrate provided with through-holes, the through-holes communicating with both main surfaces; A copper sintered body forming step of forming a copper sintered body having a porous structure so as to fill at least the through-holes; A resin impregnation step of impregnating the copper sintered body with a curable resin composition; A resin curing step of forming a conductor including the copper sintered body filled with a resin cured product in a porous manner by curing the curable resin composition impregnated in the copper sintered body; comprising: A method for manufacturing a conductor-filled through-hole substrate, wherein the porosity of the copper sintered body is 15% by volume or less based on the volume of the copper sintered body.

2. The method according to claim 1, wherein the filling rate of the resin cured product in the conductor is 80% by volume or more based on the volume of the internal space of the porous body.

3. The method according to claim 1 or 2, wherein the porosity of the copper sintered body is 1% by volume or more based on the volume of the copper sintered body.

4. The method according to any one of claims 1 to 3, wherein in the copper sintered body forming step, the copper sintered body is formed so as to cover at least a part of the main surface of the through-hole substrate.

5. The method according to claim 4, further comprising a conductor removing step of removing at least a part of the conductor formed on the main surface of the through-hole substrate.

6. The method according to claim 5, wherein the removing means in the conductor removing step is one or more selected from the group consisting of etching, mechanical polishing, and chemical mechanical polishing.

7. The method according to any one of claims 1 to 6, wherein the through-hole substrate includes a metal film provided on at least the wall surface of the through-hole.

8. The method according to any one of claims 1 to 7, wherein the ratio L / D of the hole length L to the hole diameter D of the through hole is 10 or more.

9. The copper sintered body forming step includes a copper paste filling step of filling a copper paste containing copper particles into the through holes of the through hole substrate, a copper paste firing step of firing the copper paste to form the copper sintered body, and the method according to any one of claims 1 to 8.

10. The method according to claim 9, wherein the copper paste contains, as the copper particles, first copper particles having a particle size of 0.8 μm or more and second copper particles having a particle size of 0.5 μm or less.

11. The content of the second copper particles is 35% by mass or more based on the total of the mass of the first copper particles and the mass of the second copper particles, according to the method of claim 10.

12. The method according to claim 10 or 11, wherein the first copper particles are flat.

13. The method according to any one of claims 9 to 12, wherein the copper paste is fired under a pressure of 0.1 MPa or more.

14. The method according to any one of claims 9 to 13, wherein the copper paste is fired in an atmosphere containing nitrogen or hydrogen.

15. A through hole substrate including an insulating substrate provided with through holes, the through holes communicating through both main surfaces, and a conductor filling the through holes, wherein the conductor includes a copper sintered body having a porous structure and a cured resin filled in the pores of the copper sintered body, A conductor-filled through hole substrate, wherein the porosity of the copper sintered body is 15% by volume or less based on the volume of the copper sintered body.

16. The conductor-filled through-hole substrate according to claim 15, wherein the filling rate of the resin cured product in the conductor is 80% by volume or more based on the volume of the internal space of the porous material.

17. The conductor-filled through-hole substrate according to claim 15 or 16, wherein the through-hole substrate includes a metal film provided at least on the wall surface of the through-hole.

18. The conductor-filled through-hole substrate according to any one of claims 15 to 17, wherein the ratio L / D of the hole length L to the hole diameter D of the through-hole is 10 or more.

19. The conductor-filled through-hole substrate according to any one of claims 15 to 18, wherein the conductor covers at least a part of the main surface of the through-hole substrate.

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