WO2020217358A1 - 導電体充填スルーホール基板の製造方法及び導電体充填スルーホール基板 - Google Patents
導電体充填スルーホール基板の製造方法及び導電体充填スルーホール基板 Download PDFInfo
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- WO2020217358A1 WO2020217358A1 PCT/JP2019/017505 JP2019017505W WO2020217358A1 WO 2020217358 A1 WO2020217358 A1 WO 2020217358A1 JP 2019017505 W JP2019017505 W JP 2019017505W WO 2020217358 A1 WO2020217358 A1 WO 2020217358A1
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- copper
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- hole
- sintered body
- substrate
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/09—Use of materials for the conductive, e.g. metallic pattern
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
- H05K3/12—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns
Definitions
- the present invention relates to a method for manufacturing a conductor-filled through-hole substrate and a conductor-filled through-hole substrate.
- through holes are formed in the insulating substrate, and a conductor is provided in the through holes to electrically charge both main surfaces of the substrate. A method of conducting electricity is used.
- a method of providing a conductor in the through hole a method of providing an active metal layer on the wall surface of the through hole of the insulating substrate and further filling the through hole with copper by copper plating is known.
- the aspect ratio of the through hole is increased due to the thinning of the insulating substrate and the reduction of the diameter of the through hole, voids and dimples are likely to occur in the conductor.
- Patent Document 1 a through hole is formed by copper electroplating of a DC cycle including applying a high current density for a predetermined period and applying a low current density for a predetermined period. A method of filling with copper has been proposed.
- Patent Document 1 has a problem in terms of productivity because it takes a long time to perform plating because it is necessary to suppress the precipitation rate of the copper film.
- a conductor-filled through-hole substrate in which a through-hole is filled with a conductor not only has sufficient conductivity, but also has a resistance value that does not easily increase even when subjected to a temperature change. It is required to have excellent connection reliability.
- one aspect of the present invention is a method capable of producing a conductor-filled through-hole substrate having sufficient conductivity and excellent connection reliability with high productivity, and having sufficient conductivity and connection reliability. It is an object of the present invention to provide an excellent conductor-filled through-hole substrate.
- the present inventors have formed a copper sintered body having a porous structure in the through holes of the through-hole substrate, and then the copper sintered body has a curable resin composition.
- a conductor including a copper sintered body in which the porous material was filled with the cured resin material was formed.
- the present inventors show that the conductor-filled through-hole substrate whose through-holes are filled with such a conductor shows a sufficiently low initial resistance value, and the resistance value also increases in the temperature cycle connection reliability test. We found it difficult and came to complete the present invention.
- the copper sintered body forming step A copper paste filling step of filling the through holes of the through hole substrate with a copper paste containing copper particles, A copper paste firing step of firing the copper paste to form the copper sintered body, The method according to any one of [1] to [8].
- the copper paste contains, as the copper particles, first copper particles having a particle size of 0.8 ⁇ m or more and second copper particles having a particle size of 0.5 ⁇ m or less [9]. ] The method described in. [11] The method according to [10], wherein the first copper particles are flat.
- a through-hole substrate including an insulating substrate provided with through-holes and having through-holes on both main surfaces, and a conductor for filling the through-holes are provided.
- An excellent conductor-filled through-hole substrate is provided.
- FIG. 1 to 4 are schematic views showing a method for manufacturing a conductor-filled through-hole substrate according to the embodiment.
- the method for manufacturing a conductor-filled through-hole substrate includes a preparatory step of preparing a through-hole substrate including an insulating substrate provided with through holes and having through holes on both main surfaces.
- a resin impregnation step of impregnating the copper sintered body with a curable resin composition and
- the insulating substrate 1 provided with the through hole 30 and the metal coating 2 provided on the wall surface of the through hole and the surface of the insulating substrate 1 are provided.
- the through-hole substrate 40 can be prepared.
- the through holes 30 communicate with both main surfaces of the through hole substrate 40.
- Examples of the insulating substrate 1 include an insulating substrate such as a silicon substrate, a glass substrate, a ceramic substrate, and a glass epoxy resin substrate. 1 to 4 show an embodiment in which a silicon substrate is used as the insulating substrate 1.
- the thickness of the insulating substrate 1 may be 100 ⁇ m or more, 200 ⁇ m or more, 300 ⁇ m or more from the viewpoint of suppressing warpage of the substrate after sintering, and 800 ⁇ m or less from the viewpoint of weight reduction and high density of the substrate. It may be 300 ⁇ m or less, 200 ⁇ m or less, or 100 ⁇ m or less.
- the upper limit of the hole diameter of the through hole 30 may be 200 ⁇ m or less, 100 ⁇ m or less, or 60 ⁇ m or less from the viewpoint of increasing the density of the obtained semiconductor device.
- the lower limit of the pore diameter of is not particularly limited, but may be 20 ⁇ m or more, and may be 50 ⁇ m or more.
- 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 increasing the density of the obtained semiconductor device, and the aspect ratio L of the through hole 30.
- the upper limit of / D is not particularly limited, but may be 15 or less, 10 or less, or 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 be in the above range.
- the number of through holes 30 provided in the through-hole substrate is 100 or more or 300 per 1 cm 2 of the main surface of the substrate from the viewpoint of increasing the density of the obtained semiconductor device. That may be the above.
- the metal coating 2 may be provided on both main surfaces of the insulating substrate 1 and on the wall surface of the through hole 30, and may be provided on at least one main surface of the insulating substrate 1 and on the wall surface of the through hole 30. It may or may not be provided only on the wall surface of the through hole 30.
- the through-hole substrate 40 is provided with a metal coating 2 on both main surfaces of the insulating substrate 1 and on the wall surface of the through hole 30.
- the metal coating 2 examples include titanium, nickel, chromium, copper, aluminum, palladium, platinum, gold and the like. From the viewpoint of adhesion, the metal coating 2 is preferably a coating in which titanium, nickel, and copper are layered in this order.
- 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 silicon oxide, and a titanium layer is formed on the silicon oxide to improve the adhesiveness. ..
- the nickel layer on the titanium layer and providing the copper layer on the nickel layer copper is diffused into the insulating substrate 1 as compared with the case where the copper layer is directly provided on the titanium layer. Can be suppressed.
- the adhesiveness between the copper sintered body formed in the copper sintered body forming step described later and the through-hole substrate is improved.
- a copper sintered body having a porous structure is formed so as to fill at least the through holes.
- the copper sintered body may be formed so as to cover at least a part on the main surface of the through-hole substrate.
- a conductor that fills the through holes of the through-hole substrate can be formed, and the conductor can also be provided on the main surface of the through-hole substrate. Conductors provided on the main surface of the through-hole substrate can form wiring and electrodes.
- the copper sintered body forming step includes 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. It may have and.
- a layer of copper paste can be provided on both main surfaces of the through-hole substrate 40 in or after the copper paste filling step.
- a copper paste 3 containing copper particles is applied to a through-hole substrate 40, and the copper paste 3 is filled in a through hole 30.
- layers of the copper paste 3 can be provided on both main surfaces of the through-hole substrate 40. Details of the copper paste 3 will be described later.
- 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, and slit coat. , Letterpress printing, intaglio printing, gravure printing, stencil printing, soft lithograph, bar coat, applicator, particle deposition method, spray coater, spin coater, dip coater and the like.
- the thickness of the copper paste layer may be 1 ⁇ m or more, 2 ⁇ m or more, 3 ⁇ m or more, 5 ⁇ m or more, 10 ⁇ m or more, 15 ⁇ m or more, or 20 ⁇ m or more. It may be 3000 ⁇ m or less, 1000 ⁇ m or less, 500 ⁇ m or less, 300 ⁇ m or less, 250 ⁇ m or less, 200 ⁇ m or less, 150 ⁇ m or less, or 100 ⁇ m or less.
- the copper paste 3 may be appropriately dried from the viewpoint of suppressing the flow of copper particles during the sintering of the copper paste 3 and the generation of voids in the copper sintered body.
- the atmosphere at the time of drying may be an anoxic atmosphere such as nitrogen and a rare gas, or a reducing atmosphere such as hydrogen and formic acid.
- the drying method may be drying by leaving at room temperature, heating drying, or vacuum drying.
- heat drying or vacuum drying 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 wave.
- a heating device, a heater heating device, a steam heating furnace, a hot plate pressing device, or the like 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 higher and 180 ° C. or lower.
- the drying time may be, for example, 1 minute or more and 120 minutes or less.
- the copper paste 3 is fired to sinter the copper particles contained in the copper paste 3.
- a copper sintered body-filled through-hole substrate 50 containing the porous 4, that is, the copper sintered body 5 having the porous structure fills the through holes 30 is obtained.
- a copper sintered body-filled through-hole substrate 50 in which the copper sintered body 5 is also provided on both main surfaces of the through-hole substrate 40 can be obtained. Details of the formed copper sintered body 5 will be described later.
- Baking can be done by heat treatment.
- heat treatment 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, etc.
- Heating means such as a heater heating device and a steam heating furnace can be used.
- the atmosphere at the time of firing is preferably an oxygen-free atmosphere from the viewpoint of suppressing oxidation of the copper sintered body, and more preferably a reducing atmosphere from the viewpoint of removing surface oxides of copper particles in the copper paste 3.
- the anoxic atmosphere include the introduction of an oxygen-free gas such as nitrogen and a rare gas, or under vacuum.
- the reducing atmosphere include pure hydrogen gas, a mixed gas of hydrogen and nitrogen typified by a forming gas, nitrogen containing formic acid gas, a mixed gas of hydrogen and rare gas, and a rare gas containing formic acid gas. Can be mentioned.
- the copper paste 3 When the copper paste 3 is sintered by heating without pressurization as described later, it is preferably in pure hydrogen gas or in a mixed gas of hydrogen and nitrogen typified by forming gas, and in pure hydrogen gas. More preferably. By heating in pure hydrogen gas, it becomes possible to lower the sintering temperature of copper particles. When pure hydrogen gas is used, even if the thickness of the substrate is as thick as 500 ⁇ m and the diameter of the through hole 30 is as small as 20 ⁇ m, the gas reaches the central portion of the through hole 30 to obtain the copper sintered body 5. It becomes easy.
- the maximum temperature reached during the heat treatment may be 150 ° C. or higher, 350 ° C. or lower, 300 ° C. or lower, or 260 ° C. or lower from the viewpoint of reducing heat damage to each member and improving the yield. ..
- the maximum temperature retention time may be 1 minute or more, 60 minutes or less, 40 minutes or less, or 30 minutes or less from the viewpoint of volatilizing all the dispersion medium and improving the yield.
- the copper paste may be fired under pressure.
- 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 in an atmosphere containing pure hydrogen gas. Further, 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.
- the pressure applied to the pressurizing jig A is applied to the above.
- the pressurizing jig A is not particularly limited, but may be a commercially available one, and may be manufactured by using a metal member having a flat portion.
- the pressurizing 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 pressurizing 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.
- the pressure is 20 MPa or less, it becomes easy to suppress the warp of the through-hole substrate 40.
- the present inventors infer the reason why such an effect is obtained as follows. First, when the pressure is increased, the sintering density of the copper paste (particularly, the density of the side in contact with the pressurizing jig A) increases, and the coefficient of thermal expansion of the formed copper sintered body is generally high. It is considered that the coefficient of thermal expansion of copper at 25 ° C. approaches 16.5 ⁇ m / (m ⁇ K). On the other hand, for example, the coefficient of thermal expansion of silicon at 25 ° C. is 2.6 ⁇ m / (m ⁇ K).
- the difference in the coefficient of thermal expansion between the copper sintered body and silicon increases, and it is considered that warpage is likely to occur.
- the pressure to 20 MPa or less, the increase in the density of the copper sintered body is appropriately suppressed, and as a result, the difference in the coefficient of thermal expansion between the copper sintered body and silicon becomes smaller. It is believed that the warp was suppressed.
- 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 pressurizing using a pressurizing device, a method of pressurizing using a fixing jig for pressurizing, and the like.
- the porosity of the copper sintered body formed on the main surface of the through-hole substrate is based on the total volume including the porous structure of the copper sintered body. It may be 15% by volume or less, 14% by volume or less, 12% by volume or less, or 9% by volume or less.
- 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 warpage of the through-hole substrate 40.
- the copper sintered body formed on the main surface of the through-hole substrate has the above porous structure, it is possible to reduce the coefficient of thermal expansion and reduce the difference in coefficient of thermal expansion from the insulating substrate such as a silicon substrate. It is possible to suppress cracking and warpage of the insulating substrate.
- the pore ratio of the copper sintered body filled in the through holes is 15% by volume based on the total volume including the porous structure of the copper sintered body.
- it may be 14% by volume or less, 12% by volume or less, or 9% by volume or less.
- 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 lowering the volume resistivity of the copper sintered body 5.
- the copper sintered body filled in the through hole has the above-mentioned porous structure, it is possible to suppress disconnection due to cracks in the copper sintered body after sintering.
- the porosity of the copper sintered body is calculated by the following procedure.
- (I) The cross section of the copper sintered body (cut surface in the thickness direction of the substrate) of the through-hole substrate filled with the copper sintered body is exposed by the focused ion beam.
- (Ii) A cross-sectional image (a range of 10 ⁇ m in the thickness direction of the substrate and 10 ⁇ m in the direction orthogonal to the thickness direction of the substrate) is taken with a scanning electron microscope of the exposed cross section.
- the obtained cross-sectional image is binarized so that the sintered copper portion and the porous portion are separated.
- 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 pore ratio of the copper sintered body.
- the cross section of the central portion of the copper sintered body filled in the through hole is exposed in the above (i).
- ⁇ 5 ⁇ m in the thickness direction of the substrate and the thickness of the substrate from the central part of the copper sintered body filled in the through hole Observe a range of ⁇ 5 ⁇ m in the direction orthogonal to the direction.
- the cross section of the copper sintered body on the main surface is exposed in the above (i). ..
- the region up to 5 ⁇ m from the surface of the copper sintered body formed on the main surface is defined.
- the observation points of the copper sintered body are the same as the observation points of the conductor. It can be set as appropriate so that it becomes a location.
- 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 pressurizing using a pressurizing device, a method of pressurizing using a fixing jig for pressurizing, and the like. ..
- the ratio of the copper element in the elements excluding the light element among the constituent elements may be 95% by mass or more, 97% by mass or more, or 98% by mass or more. It may be 100% by mass.
- the above ratio of the copper element in the copper sintered body is within the above range, the formation of an intermetallic compound or the precipitation of dissimilar elements at the metal copper crystal grain boundary can be suppressed, and the metallic copper constituting the copper sintered body can be suppressed. The properties tend to be strong, and even better connection reliability is likely to be obtained.
- the copper paste may be heated and fired without pressurization.
- the porosity of the copper sintered body formed on the main surface of the through-hole substrate tends to increase, and the coefficient of thermal expansion of the copper sintered body decreases, so that the through-hole substrate cracks or warps. It is less likely to occur.
- the copper sintered body 5 is impregnated with the curable resin composition by applying the curable resin composition to the copper sintered body-filled through-hole substrate 50 obtained through the copper sintered body forming step. can do.
- the curable resin composition is impregnated in the copper sintered body 5 that fills the through holes 30 and the copper sintered body 5 formed on both main surfaces of the through-hole substrate 40. It is preferable that the porous resin composition of the copper sintered body 5 is sufficiently filled with the impregnated curable resin composition.
- thermosetting compounds examples include oxetane compounds, epoxy compounds, episulfide compounds, (meth) acrylic compounds, phenol compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds and polyimide compounds.
- an epoxy compound may be used from the viewpoint of further improving the curability and viscosity of the curable resin composition and improving the characteristics and insulation reliability when left at a high temperature.
- the curable resin composition may further contain a thermosetting agent.
- the heat curing agent include an imidazole curing agent, an amine curing agent, a phenol curing agent, a polythiol curing agent, an acid anhydride, a thermal cation initiator, a thermal radical generator and the like. These may be used alone or in combination of two or more.
- an imidazole curing agent, a polythiol curing agent, or an amine curing agent is preferable because it can be cured quickly at a low temperature.
- a latent curing agent is preferable from the viewpoint of increasing 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.
- the thermosetting agent may be coated with a polymer substance such as a polyurethane resin or a polyester resin.
- the imidazole curing agent is not particularly limited, and 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimerite, 2, 4-Diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s-triazine and 2,4-diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s- Examples thereof include triazine isocyanuric acid adduct.
- the polythiol curing agent is not particularly limited, and examples thereof include trimethylolpropane tris-3-mercaptopropionate, pentaerythritol tetrakis-3-mercaptopropionate, and dipentaerythritol hexa-3-mercaptopropionate. ..
- the solubility parameter of the polythiol curing agent is preferably 9.5 or more, preferably 12 or less.
- the solubility parameter is calculated by the Fedors method. For example, the solubility parameter for trimethylolpropane tris-3-mercaptopropionate is 9.6 and the solubility parameter for dipentaerythritol hexa-3-mercaptopropionate is 11.4.
- the amine curing agent is not particularly limited, and is hexamethylenediamine, octamethylenediamine, decamethylenediamine, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraspiro [5.5].
- examples thereof include undecane, bis (4-aminocyclohexyl) methane, metaphenylenediamine and diaminodiphenylsulfone.
- thermal cation curing agent examples include an iodonium-based cation curing agent, an oxonium-based cation curing agent, and a sulfonium-based cation curing agent.
- examples of the iodonium-based cationic curing agent include bis (4-tert-butylphenyl) iodonium hexafluorophosphate and the like.
- Examples of the oxonium-based cationic curing agent examples include trimethyloxonium tetrafluoroborate.
- the sulfonium-based cationic curing agent examples include tri-p-tolylsulfonium hexafluorophosphate.
- the thermal radical generator is not particularly limited, and examples thereof include azo compounds and organic peroxides.
- examples of the azo compound include azobisisobutyronitrile (AIBN) and the like.
- examples of the organic peroxide include di-tert-butyl peroxide and methyl ethyl ketone peroxide.
- the curable resin composition can be applied by screen printing, transfer printing, offset printing, jet printing method, dispenser, jet dispenser, needle dispenser, comma coater, slit coater, die coater, gravure coater, slit coat, letterpress printing, ingot printing, Examples thereof include a method of applying by gravure printing, stencil printing, soft lithograph, bar coat, applicator, particle deposition method, spray coater, spin coater, dip coater and the like.
- the curable resin composition may be applied onto one main surface of the copper sintered body-filled through-hole substrate 50, or may be applied to a part of the main surface.
- the resin composition is applied to both surfaces of the copper sintered body-filled through-hole substrate 50, the resin composition is applied to one main surface of the copper sintered body-filled through-hole substrate 50 and filled with the copper sintered body.
- the resin composition may be permeated to the main surface side of the through-hole substrate 50 to which the resin composition has not been applied, and then the resin composition may be applied to the main surface to which the resin composition has not been applied. As a result, the resin composition can be spread over the porous 4.
- the copper sintered body-filled through-hole substrate 50 coated with the curable resin composition is left in a reduced pressure environment to improve the impregnation property of the curable resin composition into the porous 4 of the copper sintered body 5. Can be done.
- 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 cured resin product in the conductor formed through the resin curing step is within a preferable range described later.
- the porous 4 is cured by curing the curable resin composition (the curable resin composition filled in the porous 4) impregnated in the copper sintered body 5.
- a conductor 35 including a copper sintered body 5 filled with a cured resin product 6 is formed therein, and a conductor-filled through-hole substrate 51 in which at least the through holes 30 are filled with the conductor 35 can be obtained.
- a conductor 35 including a copper sintered body 5 in which a resin cured product 6 is filled in a porous 4 is also provided on both main surfaces of the through-hole substrate 40.
- Curing of the curable resin composition can be performed by heat treatment.
- Heat treatment includes hot plate, warm air dryer, hot air heater, nitrogen dryer, infrared dryer, infrared heater, far infrared heater, microwave heater, laser heater, electromagnetic heater, heater heater.
- a heating means such as a steam heating furnace can be used.
- 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, and may be a reducing atmosphere from the viewpoint of removing the surface oxide of the copper sintered body 5.
- Examples of the anoxic atmosphere include the introduction of an oxygen-free gas such as nitrogen and a rare gas, or under vacuum.
- Examples of the reducing atmosphere include pure hydrogen gas, a mixed gas of hydrogen and nitrogen typified by a forming gas, nitrogen containing formic acid gas, a mixed gas of hydrogen and rare gas, and a rare gas containing formic acid gas. Can be mentioned.
- the maximum temperature reached during the heat treatment in the resin curing step may be 150 ° C. or higher, and may be 350 ° C. or lower, 300 ° C. or lower, or 260 ° C. or lower from the viewpoint of reducing heat damage to each member and improving the yield. It may be.
- the maximum ultimate temperature is 150 ° C. or higher, the curing of the resin composition tends to proceed sufficiently when the maximum ultimate temperature retention time is 60 minutes or less.
- the conductor 35 (conductor before the conductor removing step) formed in the resin curing step may have a filling rate of the cured resin product 6 satisfying the following conditions.
- (Conductor in through hole) A) Depth from the point S1 where the line L1 extending in the thickness direction of the substrate 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) and the surface of the conductor 35 intersect.
- the filling rate of the cured resin product is 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 space of the copper sintered body. Good.
- the filling rate of the cured resin product is 80% by volume or more and 90% by volume or more based on the total volume of the porous internal space of the copper sintered body. , Or 95% by volume or more.
- the filling rate of the cured resin product is 80% by volume or more and 90% by volume or more based on the total volume of the porous internal space of the copper sintered body. , Or 95% by volume or more.
- the filling rate of the cured resin product is that of the porous copper sintered body. It 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 space.
- the filling rate of the cured resin product is the total volume of the internal space of the porous 4 of the copper sintered body 5. As a reference, it may be 80% by volume or more, 90% by volume or more, or 95% by volume or more.
- the filling rate of the cured resin product is the total volume of the internal space of the porous 4 of the copper sintered body 5.
- the filling rate of the cured resin product is 80% by volume or more and 90% by volume or more based on the total volume of the porous internal space of the copper sintered body. , Or 95% by volume or more.
- the filling rate of the cured resin product is 80% by volume or more and 90% by volume based on the total volume of the porous internal space of the copper sintered body. It may be the above, or 95% by volume or more.
- the filling rate of the cured resin product 6 in the conductor 35 is calculated by the following procedure.
- the cross section of the conductor (cut surface in the thickness direction of the substrate) of the conductor-filled through-hole substrate is exposed by the focused ion beam.
- a cross-sectional image (a range of 10 ⁇ m in the thickness direction of the substrate and 10 ⁇ m in the direction orthogonal to the thickness direction of the substrate) is taken with a scanning electron microscope of the exposed cross section.
- the obtained cross-sectional image is binarized so that the sintered copper portion and the cured resin portion and the porous portion not filled with the cured resin portion are separated.
- the cross section of the central portion of the conductor in the through hole is exposed in the above (i).
- the cross section of the conductor on the main surface is exposed in the above (i).
- ⁇ 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.
- means for removing the conductor include chemical polishing, mechanical polishing, chemical mechanical polishing, fly-cut treatment, plasma treatment, and the like.
- the fly-cut process means cutting flattening by a surface planar.
- the removing means is one or more selected from the group consisting of etching, mechanical polishing and chemical mechanical polishing from the viewpoint of being easily applicable by a general method. It is not limited to this.
- the surface of the conductor 35 formed on the main surface of the through-hole substrate 40 becomes flat, and wiring is formed. Becomes easier.
- the filling rate of the cured resin product 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 in through hole) (A) Depth from the point S3 where the line L1 extending in the thickness direction of the substrate 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) and the surface of the conductor 35 intersect.
- the filling rate of the cured resin product is 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 space of the copper sintered body. Good.
- the filling rate of the cured resin product is 80% by volume or more and 90% by volume or more based on the total volume of the porous internal space of the copper sintered body. , Or 95% by volume or more.
- the filling rate of the cured resin product is 80% by volume or more and 90% by volume or more based on the total volume of the porous internal space of the copper sintered body. , Or 95% by volume or more.
- the filling rate of the cured resin product is that of the porous copper sintered body. It 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 space.
- the filling rate of the cured resin product is the total volume of the internal space of the porous 4 of the copper sintered body 5.
- the filling rate of the cured resin product is the total volume of the internal space of the porous 4 of the copper sintered body 5. As a reference, it may be 80% by volume or more, 90% by volume or more, or 95% by volume or more.
- the filling rate of the cured resin product is 80% by volume or more and 90% by volume or more based on the total volume of the porous internal space of the copper sintered body.
- the filling rate of the cured resin product is 80% by volume or more and 90% by volume based on the total volume of the porous internal space of the copper sintered body. It may be the above, or 95% by volume or more.
- the method for manufacturing a conductor-filled through-hole substrate of the present embodiment can further include a wiring forming step.
- the wiring forming step can include a resist forming step, an etching step, and a resist removing step described below.
- the etching resist 8 is formed on the conductor 35 formed on the main surface of the through-hole substrate 40.
- a method of forming the etching resist 8 for example, a method of silk-screen printing a resist ink or a negative photosensitive dry film for an etching resist is laminated on a copper foil, and light is transmitted to the wiring shape on the laminate. Examples thereof include a method in which a photomask is overlapped and exposed with ultraviolet rays, and the unexposed portion is removed with a developing solution.
- Examples of the etching method include a method using a chemical etching solution used for a normal wiring board, such as a solution of cupric chloride and hydrochloric acid, a solution of ferric chloride, a solution of sulfuric acid and hydrogen peroxide, and a solution of ammonium persulfate. Can be mentioned.
- a chemical etching solution used for a normal wiring board such as a solution of cupric chloride and hydrochloric acid, a solution of ferric chloride, a solution of sulfuric acid and hydrogen peroxide, and a solution of ammonium persulfate.
- the method for manufacturing a through-hole substrate according to the present embodiment further includes a wiring forming step having the above steps, so that the wiring 9 including the conductor 35 can be formed on the main surface of the through-hole substrate 40.
- FIG. 4H 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 a through-hole substrate 40 provided with through holes 30 and having through holes 30 on both main surfaces, and through holes.
- a conductor 35 filled with 30 is provided, and the conductor 35 includes a copper sintered body 5 having a porous structure and a cured resin product 6 filled in the porous 4 of the copper sintered body 5.
- the metal coating 2 is provided on both main surfaces of the insulating substrate 1 and on the wall surface of the through hole, but the metal coating 2 is on the main surface. It may not be provided on the wall surface of the through hole, it may be provided only on one main surface, or it may not be provided on the wall surface of the through hole. Further, the conductor-filled through-hole substrate 52 is provided with wiring 9 including the metal coating 2 and the conductor 35 on both main surfaces of the through-hole substrate 40, but the wiring 9 is the through-hole substrate 40. It may be provided on one main surface.
- the conductor-filled through-hole substrate 52 may have a filling rate of the cured resin 6 in the conductor 35 satisfying the following conditions.
- the filling rate can be calculated in the same manner as described above.
- (Conductor in through hole) (A) Depth from the point S5 where the line L1 extending in the thickness direction of the substrate passing through the central portion C (center in the hole length L and the center in the hole diameter D there) of the through hole 30 and the surface of the conductor 35 intersect.
- the filling rate of the cured resin product is 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 space of the copper sintered body. Good.
- the filling rate of the cured resin product is 80% by volume or more and 90% by volume or more based on the total volume of the porous internal space of the copper sintered body. , Or 95% by volume or more.
- the filling rate of the cured resin product is 80% by volume or more and 90% by volume or more based on the total volume of the porous internal space of the copper sintered body. , Or 95% by volume or more.
- the filling rate of the cured resin product is that of the porous copper sintered body. It 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 space.
- the filling rate of the cured resin product is the total volume of the internal space of the porous 4 of the copper sintered body 5.
- the filling rate of the cured resin product is the total volume of the internal space of the porous 4 of the copper sintered body 5. As a reference, it may be 80% by volume or more, 90% by volume or more, or 95% by volume or more.
- the filling rate of the cured resin product is 80% by volume or more and 90% by volume or more based on the total volume of the porous internal space of the copper sintered body.
- the filling rate of the cured resin product is 80% by volume or more and 90% by volume based on the total volume of the porous internal space of the copper sintered body. It may be the above, or 95% by volume or more.
- 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.
- TSV Through-Silicon-Via
- the wiring 27 on the interposer substrate 25 and the conductor 35 of the conductor-filled through-hole substrate 51 are directly connected to fill the interposer substrate 25 and the conductor.
- the through-hole substrate 51 is flip-chip connected.
- the gap between the interposer substrate 25 and the conductor-filled through-hole substrate 51 is filled with the cured product 20 of the adhesive without gaps and sealed.
- the conductor-filled through-hole substrate 51 is repeatedly laminated 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 connected to each other by the conductor 35.
- the gaps between the conductor-filled through-hole substrates 51 are filled with the cured product 20 of the adhesive without gaps and sealed.
- the semiconductor device 100 may be obtained by, for example, the following method. That is, the conductor-filled through-hole substrate 51 is laminated via an adhesive to obtain a laminated body. The adhesive may be cured during lamination. By crimping the obtained laminate and the interposer substrate 25, they are electrically connected to form a connector in which the laminate and the interposer substrate 25 are electrically connected.
- the semiconductor device 100 is obtained by attaching a dicing tape to the surface of the formed connector opposite to the surface on which the interposer substrate 25 is provided and dicing along the dicing line.
- 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 to form an interposer.
- the substrate 25 and the conductor-filled through-hole substrate 51 are flip-chip connected.
- the gap between the interposer substrate 25 and the conductor-filled through-hole substrate 51 is filled with the cured product 20 of the adhesive without gaps and sealed.
- the conductor-filled through-hole substrate 51 is repeatedly laminated on the main surface of the conductor-filled through-hole substrate 51 on the opposite side of the interposer substrate 25 via the fine bumps 15.
- the gaps between the conductor-filled through-hole substrates 51 are filled with the cured product 20 of the adhesive without gaps and sealed.
- the semiconductor device 200 may be obtained by, for example, the following method. That is, a conductor-filled through-hole substrate 51 having fine bumps 15 provided on one main surface is laminated via an adhesive to obtain a laminated body. The adhesive may be cured during lamination. By crimping the obtained laminate and the interposer substrate 25, they are electrically connected to form a connector in which the laminate and the interposer substrate 25 are electrically connected.
- the semiconductor device 200 is obtained by attaching a dicing tape to the surface of the formed connector opposite to the surface on which the interposer substrate 25 is provided and dicing along the dicing line.
- the filling rate of the cured resin product 6 in the conductor 35 may satisfy the following conditions.
- the filling rate can be calculated in the same manner as described above.
- (Conductor in through hole) (A) In the range of ⁇ 5 ⁇ m in the thickness direction of the substrate and ⁇ 5 ⁇ m 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 product is that of the porous copper sintered body. It 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 space.
- a line L1 extending in the thickness direction of the substrate passing through the central portion C (center in the hole length L and the center in the hole diameter D there) of the through hole 30 and a surface S10 including the main surface of the insulating substrate are formed.
- the filling rate of the cured resin is 80% by volume or more, 90% by volume or more, or 95 volumes based on the total volume of the porous internal space of the copper sintered body. It may be% or more.
- the filling rate of the cured resin product is 80% by volume or more and 90% by volume or more based on the total volume of the porous internal space of the copper sintered body. , Or 95% by volume or more.
- the filling rate of the cured resin product is 80% by volume or more and 90% by volume or more based on the total volume of the porous internal space of the copper sintered body. , Or 95% by volume or more.
- Copper paste A copper paste containing copper particles used in the method for manufacturing a conductor-filled through-hole substrate of the present embodiment will be described.
- the copper paste may contain, for example, first copper particles having a particle size (maximum diameter) of 0.8 ⁇ m or more as copper particles.
- the particle size (maximum diameter) of the first copper particles may be 1.2 ⁇ m or more.
- the particle size (maximum diameter) of the first copper particles may be 10 ⁇ m or less, and may be 8.0 ⁇ m or less.
- the average particle size (average maximum diameter) of the first copper particles contained in the copper paste is 0.5 ⁇ m or more from the viewpoint of improving the sintering density in the through holes and suppressing voids generated in the through holes. , 0.8 ⁇ m or more, or 1.2 ⁇ m or more, and may be 20 ⁇ m or less, 10 ⁇ m or less, or 8 ⁇ m or less.
- the particle size (maximum diameter) and average particle size (average maximum diameter) of the first copper particles can be obtained from, for example, an SEM image of the particles.
- a method of calculating the particle size (maximum diameter) of the first copper particles from the SEM image will be illustrated.
- the powder of the first copper particles is placed on a carbon tape for SEM with a spatula to prepare a sample for SEM. This SEM sample is observed with an SEM device at a magnification of 5000.
- a rectangle circumscribing the first copper particles of the SEM image is drawn by image processing software, and the long side of the rectangle is the particle size (maximum diameter) of the particles. Using a plurality of SEM images, this measurement is performed on 50 or more first copper particles, and the average value (average maximum diameter) of the particle size is calculated.
- the shape of the first copper particles may be, for example, spherical, lumpy, needle-shaped, flat (flake-shaped), substantially spherical, or the like.
- the first copper particles may be agglomerates of copper particles having these shapes.
- the first copper particles are preferably flat (flakes) having an aspect ratio (major axis / thickness) of 4 or more.
- the volume shrinkage when the copper particles in the copper paste are sintered is suppressed, and the copper particles are generated in the through holes. It becomes easy to suppress voids. Further, by suppressing the volume 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 main surface of the through-hole substrate.
- 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.
- the aspect ratio is within the above range, the first copper particles in the copper paste are likely to be oriented parallel to the coated surface of the copper paste, and the volume when the copper particles in the copper paste are sintered. Shrinkage can be suppressed.
- the wiring is formed from the conductor provided on the main surface of the through-hole substrate, the disconnection due to the thermal stress of the wiring can be further suppressed.
- the adhesion between the copper sintered body and the metal film formed on the insulating substrate can be improved.
- the aspect ratio (major axis / thickness) 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 thickness.
- the copper paste preferably contains first copper particles having a particle size (maximum diameter) of 0.8 ⁇ m or more and 10 ⁇ m or less and an aspect ratio of 4 or more.
- first copper particles having a particle size (maximum diameter) of 0.8 ⁇ m or more and 10 ⁇ m or less and an aspect ratio of 4 or more.
- the copper paste may contain copper particles having a particle size (maximum diameter) of 0.8 ⁇ m or more and 10 ⁇ m or less and an aspect ratio of less than 2, but the particle size (maximum diameter) is 0.8 ⁇ m or more and 10 ⁇ m or less.
- the content of the copper particles having an aspect ratio of less than 2 is 100 parts by mass of the first copper particles having a particle size (maximum diameter) of 0.8 ⁇ m or more and 10 ⁇ m or less and an aspect ratio of 4 or more. It may be 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.
- the first copper particles in the copper paste cause voids in the through holes. It is possible to form a copper sintered body having a porous structure but having a sufficiently conductive network formed in the through holes while suppressing the occurrence of the above. Further, on the main surface of the through-hole substrate, the first copper particles are likely to be oriented substantially parallel to the coated surface of the copper paste, and cracks are less likely to occur by suppressing volume shrinkage more effectively.
- a copper sintered body can be formed, and when wiring is formed from a conductor containing the copper sintered body, disconnection due to thermal stress of the wiring can be further suppressed.
- 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 is 85% by mass, based on the total mass of the metal particles contained in the copper paste. % Or less, 70% by mass or less, or 50% by mass or less. When the content of the first copper particles is within the above range, the above-mentioned effect can be more easily obtained.
- the first copper particles may be treated with a surface treatment agent from the viewpoint of dispersion stability and oxidation resistance.
- the surface treatment agent may be one that is removed at the time of wiring formation (sintering of copper particles).
- Examples of such a surface treatment agent include aliphatic carboxylic acids such as palmitic acid, stearyl acid, arachidic acid, and oleic acid; aromatic carboxylic acids such as terephthalic acid, pyromellitic acid, and o-phenoxybenzoic acid; and cetyl alcohols.
- Fatty alcohols such as stearyl alcohol, isobornylcyclohexanol, tetraethyleneglycol; aromatic alcohols such as p-phenylphenol; alkylamines such as octylamine, dodecylamine, stearylamine; stearonitrile, decanenitrile, etc. Examples thereof include aliphatic nitriles; silane coupling agents such as alkylalkoxysilanes; polymer treatment agents such as polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, and silicone oligomers. As the surface treatment agent, one type may be used alone, or two or more types may be used in combination.
- the treatment amount of the surface treatment agent may be an amount of one molecular layer or more on the particle surface.
- the treatment amount of such a 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 coating area of the surface treatment agent.
- the treatment amount of the surface treatment agent is usually 0.001% by mass or more.
- the treatment amount of the surface treatment agent is the number of molecular layers (n) adhering to the surface of the first copper particles, the specific surface area ( Ap ) of the first copper particles (unit: m 2 / g), and the surface treatment agent. of molecules (M s) (unit g / mol), the minimum coverage area of the surface treatment agent (S S) (unit m 2 / piece), from Avogadro's number (N a) (6.02 ⁇ 10 23 pieces) Can be calculated.
- the specific surface area of the first copper particles can be calculated by measuring the dried copper particles by the BET specific surface area measuring method.
- Minimum coverage of the surface treatment agent if the surface treatment agent is a straight-chain saturated fatty acids, is 2.05 ⁇ 10 -19 m 2/1 molecule.
- calculation from a molecular model, or "Chemistry and Education” (Akihiro Ueda, Sumio Inafuku, Iwao Mori, 40 (2), 1992, p114-117). It can be measured by the method described. An example of a method for quantifying a surface treatment agent is shown.
- the surface treatment agent can be identified by a thermal desorption gas / gas chromatograph mass spectrometer of the dry powder obtained by removing the dispersion medium from the copper paste, whereby 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 content analysis. Examples of the carbon content analysis method include a high-frequency induction heating furnace combustion / infrared absorption method.
- the amount of the surface treatment agent can be calculated from the carbon number, molecular weight and carbon content ratio of the identified surface treatment agent by the above formula.
- the first copper particles commercially available ones can be used.
- the first copper particles on the market include MA-C025 (manufactured by Mitsui Mining & Smelting Co., Ltd., average particle size 4.1 ⁇ m) and 3L3 (manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., average particle size 7.3 ⁇ m). ), 1110F (Mitsui Mining & Smelting Co., Ltd., average particle size 5.8 ⁇ m), 2L3 (Fukuda Metal Foil Powder Industry Co., Ltd., average particle size 9 ⁇ m).
- the particle size (maximum diameter) is 0.8 ⁇ m or more and 10 ⁇ m or less, the first copper particles having an aspect ratio of 4 or more are contained, and the particle size (maximum diameter) is 0.8 ⁇ m or more.
- Copper particles having a content of 10 ⁇ m or less and an aspect ratio of less than 2 in the above-mentioned range can be used.
- a commercially available product made of such copper particles may be selected and used.
- the ratio [pore diameter ( ⁇ m) / particle size ( ⁇ m)] of the pore diameter of the through hole to the particle size (maximum diameter) of the first copper particle is a copper sintered body that suppresses volume shrinkage and is less likely to cause cracks. It 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 being able to form.
- the copper paste can include the above-mentioned first copper particles and the second copper particles having a particle size (maximum diameter) of 0.5 ⁇ m or less.
- the second copper particles are interposed between the first copper particles, so that the conductivity of the obtained wiring tends to be improved. That is, it is preferable to use the first copper particles and the second copper particles in combination.
- the copper paste is prepared only from the second copper particles, the volume shrinkage and the sintering shrinkage due to the drying of the dispersion medium are large. Therefore, when the copper particles are sintered, they are baked from the metal coating provided on the insulating substrate. The body is easily peeled off, and it is difficult to obtain sufficient airtightness and connection reliability.
- the first copper particles and the second copper particles in combination by using the first copper particles and the second copper particles in combination, the volume when the copper paste is sintered Shrinkage is suppressed, and the adhesiveness between the copper sintered body formed in the through hole and the metal coating formed on the wall surface of the through hole can be improved. As a result, the copper sintered body in the through hole is less likely to be broken due to thermal stress, and the airtightness and connection reliability against thermal stress are further improved.
- the second copper particle can act as a copper particle that suitably joins the first copper particles.
- the second copper particles are superior in sinterability to the first copper particles, and can have a function of promoting the sintering of the copper particles. For example, it is possible to sinter the copper particles at a lower temperature as compared with the case where the first copper particles are used alone.
- the volume shrinkage and the sintering shrinkage due to the drying of the dispersion medium are large, so that the copper sintered body formed inside the through hole shrinks in volume. Voids are likely to occur inside the through hole.
- the flat first copper particles and the second copper particles act as copper particles suitably bonded by the second copper particles. This makes it easy to form a copper sintered body having a porous structure while suppressing the generation of voids inside the through holes.
- the average particle size (average maximum diameter) of the second copper particles contained in the copper paste is 0.01 ⁇ m or more, 0.03 ⁇ m or more, 0.05 ⁇ m or more, 0.08 ⁇ m or more, 0.1 ⁇ m or more, or 0.2 ⁇ m. It may be 0.5 ⁇ m or less, 0.4 ⁇ m or less, 0.3 ⁇ m or less, or 0.2 ⁇ m or less.
- the average particle size (average maximum diameter) of the second copper particles is 0.01 ⁇ m or more, the effects of suppressing the synthesis cost of the second copper particles, good dispersibility, and suppressing the amount of the surface treatment agent used can be obtained. It will be easier to obtain.
- the average particle size (average maximum diameter) of the second copper particles is 0.5 ⁇ m or less, the effect of excellent sinterability of the second copper particles can be easily obtained.
- the second copper particles may contain 20% by mass or more of copper particles having a particle size (maximum diameter) of 0.01 ⁇ m or more and 0.5 ⁇ m or less. From the viewpoint of the sinterability of the copper paste, the second copper particles may contain 30% by mass or more of copper particles having a particle size of 0.01 ⁇ m or more and 0.5 ⁇ m or less, and may contain 50% by mass or more. It may contain 85% by mass or less.
- the content ratio of the copper particles having a particle size (maximum diameter) of 0.01 ⁇ m or more and 0.5 ⁇ m or less in the second copper particles is 20% by mass or more, the dispersibility of the copper particles is further improved and the viscosity is increased. The decrease in paste concentration can be further suppressed.
- the content of the second copper particles in the copper paste is 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. It may be 85% by mass or less, 80% by mass or less, or 75% by mass or less.
- a copper sintered body having excellent adhesion to the metal coating provided on the through-hole substrate can be obtained while suppressing the generation of voids in the through holes. It is possible to form a copper sintered body that is easy to form and less likely to cause cracks on the main surface of the through-hole substrate, and when the wiring is formed from the conductor containing this copper sintered body, the heat of the wiring is generated. It is possible to further suppress disconnection due to stress.
- 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 of the mass of the first copper particles and the mass of the second copper particles. Good.
- 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.
- the wiring formed from the conductor including the copper sintered body is less likely to be broken due to thermal stress.
- 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 the voids can be suppressed.
- a copper sintered body in which cracks are unlikely to occur can be formed, and the wiring formed from the conductor containing the copper sintered body is less likely to be broken due to thermal stress.
- the content of the second copper particles is 20 parts by mass or more and 30 mass based on the total of the mass of the first copper particles and the mass of the second copper particles. % Or more, 35% by mass or more, or 40% by mass or more, and may be 85% by mass or less or 80% by mass or less.
- the shape of the second copper particle may be, for example, spherical, lumpy, needle-like, flat (flake-like), substantially spherical, or the like.
- the second copper particle may be an agglomerate of copper particles having these shapes. From the viewpoint of dispersibility and filling property, the shape of the second copper particle may be spherical, substantially spherical, or flat (flake-like), and from the viewpoint of flammability, mixing with the first copper particle, and the like. Therefore, it may be spherical or substantially spherical.
- the aspect ratio of the second copper particles may be 5 or less, 4 or less, or 3 or less from the viewpoint of dispersibility, filling property, and mixing property with the first copper particles.
- the second copper particles may be treated with a specific surface treatment agent.
- Specific surface treatment agents include, for example, organic acids having 8 to 16 carbon atoms. Examples of organic acids having 8 to 16 carbon atoms include caprylic acid, methylheptanic acid, ethylhexanoic acid, propylpentanoic acid, pelargonic acid, methyloctanoic acid, ethylheptanic acid, propylhexanoic acid, capric acid, methylnonanoic acid, and ethyl.
- Saturated fatty acids Saturated fatty acids; octenoic acid, nonenic acid, methylnonenic acid, decenoic acid, undecenoic acid, dodecenoic acid, tridecenoic acid, tetradecenoic acid, myristoleic acid, pentadecenoic acid, hexadecenoic acid, palmitreic acid, sabienoic acid and other unsaturated fatty acids; Aromas such as acid, pyromellitic acid, o-phenoxybenzoic acid, methylbenzoic acid, ethyl benzoic acid, propyl benzoic acid, butyl benzoic acid, pentyl benzoic acid, hexyl benzoic acid, heptyl benzoic acid, octyl benzoic acid, nonyl benzoic acid, etc.
- Group carboxylic acids include.
- One type of organic acid may be used alone, or two or more types may be used in combination. By combining such an organic acid with the second copper particles, there is a tendency that both the dispersibility of the second copper particles and the desorption of the organic acid at the time of sintering can be achieved at the same time.
- the amount of the surface treatment agent to be treated may be an amount that adheres to the surface of the second copper particles in a single-layer to a triple-layer.
- 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 is 2.1% by mass or less, 1.6% by mass or less, or 1 It may be 1% by mass or less.
- the surface treatment amount of the second copper particles can be calculated for the first copper particles by the method described above. 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.
- the second copper particle a synthesized one or a commercially available one can be used.
- the total content of the first copper particles and the content of 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.
- the total content of the first copper particles and the content of the second copper particles is within the above range, it becomes easy to suppress the generation of voids in the through holes. From the viewpoint that such an effect can be more easily obtained, the total content of the first copper particles and the content of the second copper particles is 95% by mass or more based on the total mass of the metal particles. It may be 100% by mass.
- the copper paste may further contain other metal particles other than copper particles.
- other metal particles include particles such as nickel, silver, gold, palladium, and platinum.
- the average particle size (maximum diameter) of the other metal particles may be 0.01 ⁇ m or more or 0.05 ⁇ m or more, and may be 5 ⁇ m or less, 3.0 ⁇ m or less, or 2.0 ⁇ m or less.
- the content thereof may be less than 20% by mass and 10% by mass based on the total mass of the metal particles contained in the copper paste from the viewpoint of obtaining sufficient bondability. It may be as follows.
- Other metal particles may not be included.
- the shapes of the other metal particles are not particularly limited.
- the dispersion medium contained in the copper paste is not particularly limited, and may be, for example, volatile.
- volatile dispersion medium include monovalent and polyvalent and polyvalent such as pentanol, hexanol, heptanol, octanol, decanol, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, ⁇ -terpineol and isobornylcyclohexanol (MTPH).
- Valuable alcohols 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.
- Examples of mercaptans having an alkyl group having 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, and hexyl mercaptan. And dodecyl mercaptan.
- Examples of mercaptans having a cycloalkyl group having 5 to 7 carbon atoms include cyclopentyl mercaptan, cyclohexyl mercaptan and cycloheptyl mercaptan.
- 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, with the total mass of the metal particles contained in the copper paste as 100 parts by mass, 20 parts by mass or less, 16 parts by mass. It may be 10 parts or less, or 12 parts by mass or less.
- the copper paste can be adjusted to a more appropriate viscosity, and it becomes easy to suppress the generation of voids in the through holes.
- wetting improvers such as nonionic surfactants and fluorine-based surfactants; defoaming agents such as silicone oil; ion trapping agents such as inorganic ion exchangers, etc. are appropriately added to the copper paste, if necessary. May be good.
- the copper paste described above can be prepared by mixing copper particles and arbitrary components (additives, other metal particles, etc.) with a dispersion medium. After mixing each component, stirring treatment may be performed. The maximum diameter of the dispersion may be adjusted by a classification operation.
- the second copper particles, the surface treatment agent, and the dispersion medium are mixed in advance, and the dispersion treatment is performed to prepare a dispersion liquid of the second copper particles, and further, the first copper particles and other metal particles. And any additive may be mixed and prepared.
- the dispersibility of the second copper particles is improved, the miscibility with the first copper particles is improved, 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.
- the copper particles synthesized above were observed with a transmission electron microscope (manufactured by JEOL Ltd., product name: JEM-2100F).
- the mean value of the semimajor axis of 200 randomly selected copper particles was 104 nm.
- the shape of the second particle was spherical.
- a copper paste was prepared by mixing 5 parts by mass of diethylene glycol (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) and 5 parts by mass of resin components.
- a mixture mixed by mass ratio was used.
- Examples 1 to 73 and Comparative Example 1 A silicon substrate having through holes and having a titanium layer, a nickel layer, and a copper layer formed in this order on both main surfaces and on the wall surface of the through holes was prepared as a through-hole substrate.
- the diameter of the silicon substrate is 6 inches and the thickness is 500 ⁇ m.
- the hole diameters of the through holes on the silicon substrate are shown in Tables 1 to 8.
- the titanium layer, nickel layer, and copper layer are sequentially formed by sputtering.
- Examples 1 to 8, 12 to 21, 24 to 43, 48 to 73 and Comparative Example 1> The prepared copper paste was applied on both main surfaces of the silicon substrate with a metal spatula, and the copper paste was filled in the through holes. After application, the copper paste was dried in the air at 90 ° C. for 10 minutes. After drying, a copper paste layer having a thickness of 30 ⁇ m was formed on the silicon substrate.
- the silicon substrate on which the copper paste layer was formed was pressed from both sides with a pressure jig.
- the pressure applied to the silicon substrate was set to the pressure shown in Tables 1 to 8.
- the pressurizing jig includes a flat aluminum plate and a spring, and can adjust the pressure during pressurization.
- a silicon substrate pressurized by a pressurizing 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.
- the copper paste was sintered by sintering treatment under the conditions of a temperature rise of 10 minutes and a temperature of 300 ° C.
- the thickness of the copper sintered body formed on both main surfaces of the silicon substrate after sintering was 25 ⁇ m.
- 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 pressurized by the pressurizing jig. The thickness of the copper sintered body formed on both main surfaces of the silicon substrate after sintering was 35 ⁇ m.
- 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 silicon substrate after sintering was 30 ⁇ m.
- 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 rising time was 10 minutes and the sintering treatment was performed at 225 ° C. for 60 minutes. The thickness of the copper sintered body formed on both main surfaces of the silicon substrate after sintering was 30 ⁇ m.
- Examples 1 to 73 The curable resin composition shown below was applied to one side of a copper sintered body-filled through-hole substrate by a roll coater. Next, a copper sintered body-filled through-hole substrate was placed in a container, and the inside of the container was sucked so that the gauge pressure was 100 KPa to create a vacuum state. The copper sintered body-filled through-hole substrate was held for 10 minutes in a vacuum state, and then the copper sintered body-filled through-hole substrate was taken out of the container.
- the through-hole copper sintered body is impregnated with the curable resin composition, and the curable resin composition reaches the surface opposite to the surface of the through-hole copper sintered body coated with the curable resin composition. I confirmed that.
- the curable resin composition remaining on the coated surface of the curable resin composition of the copper sintered body-filled through-hole substrate was removed with a rubber spatula.
- the curable resin composition was applied to the surface opposite to the surface to which the curable resin composition was applied by a roll coater, and the curable resin composition remaining on the surface of the copper sintered body-filled through-hole substrate was applied with a rubber spatula.
- a rubber spatula was removed as much as possible.
- 2PZ-CN manufactured by Shikoku Kasei Co., Ltd., trade name of imidazole compound
- Examples 1 to 73> A conductor-filled through-hole substrate was obtained by holding a through-hole substrate in which a copper sintered body was impregnated with a curable resin composition at 180 ° C. for 1 hour in a nitrogen atmosphere.
- the obtained cross-sectional image is separated into a sintered copper portion and a cured resin portion and a space not filled by the cured resin portion in the porous portion by using image analysis software (Adobe Photoshop (registered trademark) Elements). It was binarized. For each of the five observation points, the ratio of the area of the space not filled with the cured resin in the porous portion to the total area of the cross section of the conductor was calculated and used as the porosity. The average value of the vacancy rate of the observations at 5 points was taken as the vacancy rate of the conductor. By substituting the pore ratio of the copper sintered body and the pore ratio of the conductor into the following formula (1), the filling rate of the cured resin product in the conductor was calculated.
- Examples 1 to 73 and Comparative Example 1> A dry film HW425 (manufactured by Hitachi Kasei Kogyo Co., Ltd., trade name) for UV-curable etching resist is crimped with a laminator on the surface of the copper sintered body on both sides of the conductor-filled through-hole substrate that has been mechanically polished. did. After that, the wiring pattern was exposed with a photomask, and the wiring was formed through resist development-etching of the copper sintered body-resist removal to obtain a conductor-filled through-hole substrate (test piece 55) shown in FIG. It was. In the obtained conductor-filled through-hole substrate (test piece 55), the conductor filled in the through hole is electrically connected by a conductor (wiring) provided on the surface of the substrate.
- connection connection resistance value was measured as the initial resistance value of the conductor-filled through-hole substrate (test piece 55).
- the hole diameter of the through hole of the silicon substrate is 20 ⁇ m
- the resistance value of 20 through holes connected and when the hole diameter of the through hole of the silicon substrate is 30 ⁇ m, the resistance value of 30 through holes connected.
- the hole diameter of the through hole of the silicon substrate is 50 ⁇ m
- the resistance value in which 30 through holes are connected is connected
- the hole diameter of the through hole of the silicon substrate is 100 ⁇ m, 100 through holes are connected.
- the hole diameter of the through hole of the silicon substrate was 200 ⁇ m, the resistance value was measured by connecting 200 through holes.
- the measured connection connection resistance value was evaluated according to the following criteria. Those with an evaluation of B or higher were judged to be good. The results are shown in Tables 1-8.
- Examples 1 to 73 and Comparative Example 1> The conductor-filled through-hole substrate (test piece 55) is set in a temperature cycle tester (TSA-72SE-W, manufactured by Espec Co., Ltd.), and the low temperature side: -40 ° C, 15 minutes, room temperature: 2 minutes, high temperature side: The temperature cycle connection reliability test was carried out under the conditions of 125 ° C., 15 minutes, defrosting cycle: automatic, number of cycles: 50, 100, 300, 500 cycles.
- TSA-72SE-W temperature cycle tester
- the resistance value in which 30 through holes are connected is connected, and when the hole diameter of the through hole of the silicon substrate is 100 ⁇ m, 100 through holes are connected.
- the hole diameter of the through hole of the silicon substrate was 200 ⁇ m, the resistance value was measured by connecting 200 through holes.
- the measured connection connection resistance value was evaluated according to the following criteria. Those having an evaluation of B or higher after 500 times of the temperature cycle test were judged to be good. The results are shown in Tables 1-8.
- Examples 1 to 73 and Comparative Example 1> The conductor-filled through-hole substrate (test piece 55) was visually confirmed to confirm the presence or absence of cracks in the silicon substrate. The case where there was no crack was evaluated as ⁇ , and the case where there was even a partial crack was evaluated as ⁇ . The results are shown in Tables 1-8.
- 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, a conductor-filled through-hole substrate is set on a jig, vacuuming is performed until the inlet pressure of the measuring machine reaches 5 Pa, and when the inlet pressure reaches 5 Pa, He pressurization (0.1 MPa) is performed. After 30 seconds, the amount of leak was measured and evaluated according to the following criteria. The results are shown in Tables 1-8.
- Leakage amount is less than 1 ⁇ 10-11 Pa ⁇ m 3 / sec
- Leakage amount is 1 ⁇ 10-11 or more and 1 ⁇ 10 -10 Pa ⁇ m 3 / sec or less
- Leakage amount is 1 ⁇ 10 -9 or more and less than 1 ⁇ 10 -8 Pa ⁇ m 3 / sec
- 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.
- Adhesion strength (MPa) breaking load (kgf) / breaking area (mm 2 ) x 9.8 (N / kgf).
- Adhesion strength (MPa) is less than 5 MPa
- Examples 1 to 73 and Comparative Example 1> The conductor-filled through-hole substrate obtained in the same manner except that five wiring patterns of 2 mm ⁇ 2 mm were formed in the wiring formation step was inspected with an optical microscope, and cracks (length 0.5 mm or more) were found in the wiring pattern. The presence or absence was inspected. The magnification was set to 500 times, and the evaluation was made according to the following criteria. The results are shown in Tables 1-8. A: No cracks B: 1 or more cracks and less than 2 C: 2 or more cracks and less than 5 D: 5 or more cracks and less than 10 E: 10 or more cracks and less than 20 cracks F: 20 or more cracks
- Examples 1 to 73 and Comparative Example 1> The volume resistivity of the conductor formed on the silicon substrate was measured.
- the volume resistivity is the surface resistance value measured by a 4-ended needle surface resistance measuring instrument (manufactured by Mitsubishi Analytech Co., Ltd., trade name: Loresta GP) and the non-contact surface / layer cross-sectional shape measurement system (VertScan, Ryoka System Co., Ltd.). ) was calculated from the film thickness. The results are shown in Tables 1-8.
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- Manufacturing Of Printed Wiring (AREA)
Abstract
Description
[1] 貫通孔が設けられている絶縁性基体を含み、両主面に貫通孔が通じているスルーホール基板を準備する準備工程と、
少なくとも上記貫通孔を充填するように、ポーラス構造を有する銅焼結体を形成する銅焼結体形成工程と、
上記銅焼結体に硬化性樹脂組成物を含浸する樹脂含浸工程と、
上記銅焼結体に含浸させた上記硬化性樹脂組成物を硬化することにより、ポーラスに樹脂硬化物が充填された上記銅焼結体を含んでなる導電体を形成する樹脂硬化工程と、
を備える、導電体充填スルーホール基板の製造方法。
[3] 上記銅焼結体の空孔率が、上記銅焼結体の体積を基準として、1~15体積%である、[1]又は[2]に記載の方法。
[4] 上記銅焼結体形成工程において、上記銅焼結体を、上記スルーホール基板の主面上の少なくとも一部を被覆するように形成する、[1]~[3]のいずれかに記載の方法。
[5] 上記スルーホール基板の主面上に形成された上記導電体の少なくとも一部を除去する導電体除去工程を更に備える、[4]に記載の方法。
[6] 上記導電体除去工程における除去手段が、エッチング、機械的研磨及び化学的機械的研磨からなる群より選択される一種以上である、[5]に記載の方法。
[7] 上記スルーホール基板が、少なくとも上記貫通孔の壁面に設けられた金属被膜を備える、[1]~[6]のいずれかに記載の方法。
[8] 上記貫通孔の孔径Dに対する孔長Lの比L/Dが10以上である、[1]~[7]のいずれかに記載の方法。
上記スルーホール基板の上記貫通孔に銅粒子とを含む銅ペーストを充填する銅ペースト充填工程と、
上記銅ペーストを焼成して上記銅焼結体を形成する銅ペースト焼成工程と、
を有する、[1]~[8]のいずれかに記載の方法。
[10] 上記銅ペーストが、上記銅粒子として、粒径が0.8μm以上である第1の銅粒子と、粒径が0.5μm以下である第2の銅粒子と、を含む、[9]に記載の方法。
[11] 上記第1の銅粒子が扁平状である、[10]に記載の方法。
[12] 上記銅ペーストを0.1MPa以上の加圧下で焼成する、[9]~[11]のいずれかに記載の方法。
[13] 上記銅ペーストを窒素又は水素を含む雰囲気下で焼成する、[9]~[12]のいずれかに記載の方法。
[14] 貫通孔が設けられている絶縁性基体を含み、両主面に貫通孔が通じているスルーホール基板と、貫通孔を充填する導電体と、を備え、
上記導電体が、ポーラス構造を有する銅焼結体と、銅焼結体のポーラスに充填された樹脂硬化物と、を含む、導電体充填スルーホール基板。
[16] 上記スルーホール基板が、少なくとも上記貫通孔の壁面に設けられた金属被膜を備える、[14]又は[15]に記載の導電体充填スルーホール基板。
[17] 上記貫通孔の孔径Dに対する孔長Lの比L/Dが10以上である、[14]~[16]のいずれかに記載の導電体充填スルーホール基板。
[18] 上記導電体が、上記スルーホール基板の主面上の少なくとも一部を被覆する、[14]~[17]のいずれかに記載の導電体充填スルーホール基板。
図1~図4は、一実施形態の導電体充填スルーホール基板の製造方法を示す模式図である。
少なくとも上記貫通孔を充填するように、ポーラス構造を有する銅焼結体を形成する銅焼結体形成工程と、
上記銅焼結体に硬化性樹脂組成物を含浸する樹脂含浸工程と、
上記銅焼結体に含浸させた上記硬化性樹脂組成物を硬化することにより、ポーラスに樹脂硬化物が充填された上記銅焼結体を含んでなる導電体を形成する樹脂硬化工程と、
上記スルーホール基板の主面上に形成された上記導電体の少なくとも一部を除去する導電体除去工程と、
を備える。
この工程では、図1(a)に示されるように、貫通孔30が設けられている絶縁性基体1と、貫通孔の壁面及び絶縁性基体1の表面に設けられた金属被膜2とを有するスルーホール基板40を準備することができる。貫通孔30は、スルーホール基板40の両主面に通じている。
この工程では、少なくとも貫通孔を充填するように、ポーラス構造を有する銅焼結体を形成する。本実施形態においては、銅焼結体を、スルーホール基板の主面上の少なくとも一部を被覆するように形成してもよい。この場合、スルーホール基板の貫通孔を充填する導電体を形成するとともに、スルーホール基板の主面上にも導電体を設けることができる。スルーホール基板の主面上に設けられた導電体は、配線及び電極を形成することができる。
(i)集束イオンビームによって銅焼結体充填スルーホール基板の銅焼結体の断面(基板の厚み方向の切断面)を露出させる。
(ii)露出させた断面を走査型電子顕微鏡により断面画像(基板の厚み方向に10μm及び基板の厚み方向と直交する方向に10μmの範囲)を撮影する。
(iii)焼結銅部分とポーラス部分とが分かれるように、得られた断面画像を2値化処理する。
(iv)2値化処理された断面画像から、銅焼結体断面の全面積に対するポーラス部分の面積の比率を銅焼結体の空孔率とする。
貫通孔に充填された銅焼結体の空孔率を算出する場合には、上記(i)において、貫通孔に充填された銅焼結体の中央部の断面を露出させる。貫通孔に充填された銅焼結体の中央部の空孔率を算出する場合には、貫通孔に充填された銅焼結体の中央部から、基板の厚み方向に±5μm及び基板の厚み方向と直交する方向に±5μmの範囲を観察する。銅焼結体充填スルーホール基板の主面上に形成された銅焼結体の空孔率を算出する場合には、上記(i)において、主面上の銅焼結体の断面を露出させる。銅焼結体充填スルーホール基板の主面上に形成された銅焼結体の空孔率を算出する場合には、主面上に形成された銅焼結体の表面から5μmまでの領域を観察する。
後述する導電体における樹脂硬化物の充填率の算出のために用いられる銅焼結体の空孔率の算出の際には、銅焼結体の観察箇所は、導電体の観察箇所と同様の箇所となるように適宜設定することができる。
この工程では、例えば、銅焼結体形成工程を経て得られる銅焼結体充填スルーホール基板50に硬化性樹脂組成物を塗布することで、銅焼結体5に硬化性樹脂組成物を含浸することができる。本実施形態では、貫通孔30を充填する銅焼結体5及びスルーホール基板40の両主面上に形成された銅焼結体5に硬化性樹脂組成物が含浸される。なお、含浸した硬化性樹脂組成物によって、銅焼結体5のポーラス4が充分に充填されることが好ましい。
硬化性樹脂組成物を構成する成分としては、熱硬化性化合物が挙げられる。熱硬化性化合物としては、オキセタン化合物、エポキシ化合物、エピスルフィド化合物、(メタ)アクリル化合物、フェノール化合物、アミノ化合物、不飽和ポリエステル化合物、ポリウレタン化合物、シリコーン化合物及びポリイミド化合物等が挙げられる。なかでも、硬化性樹脂組成物の硬化性及び粘度をより一層良好にし、高温放置における特性や絶縁信頼性を向上させる点から、エポキシ化合物であってよい。
この工程では、図2(d)に示されるように、銅焼結体5に含浸させた硬化性樹脂組成物(ポーラス4に充填された硬化性樹脂組成物)を硬化させることで、ポーラス4に樹脂硬化物6が充填された銅焼結体5を含んでなる導電体35が形成され、少なくとも貫通孔30に導電体35が充填された導電体充填スルーホール基板51を得ることができる。本実施形態の場合、スルーホール基板40の両主面上にもポーラス4に樹脂硬化物6が充填された銅焼結体5を含んでなる導電体35が設けられている。
(貫通孔の導電体)
(a)貫通孔30の中央部C(孔長Lにおける中心且つそこでの孔径Dにおける中心)、を通り、基板の厚み方向に伸びる線L1と、導電体35の表面とが交わる点S1から深さ10μmまでの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(b)上記点S1から深さ10~20μmの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(c)上記点S1から深さ20~30μmの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(d)貫通孔30の中央部Cから、基板の厚み方向に±5μm及び基板の厚み方向と直交する方向に±5μmの範囲において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(e)基板の主面に形成された導電体35の表面S2から深さ5μmまでの領域において、樹脂硬化物の充填率が、銅焼結体5のポーラス4の内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(f)基板の主面に形成された導電体35の表面S2から深さ10μmまでの領域において、樹脂硬化物の充填率が、銅焼結体5のポーラス4の内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(g)上記表面S2から深さ10~20μmの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(h)上記表面S2からの深さ20~30μmの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(i)集束イオンビームによって導電体充填スルーホール基板の導電体の断面(基板の厚み方向の切断面)を露出させる。
(ii)露出させた断面を走査型電子顕微鏡により断面画像(基板の厚み方向に10μm及び基板の厚み方向と直交する方向に10μmの範囲)を撮影する。
(iii)焼結銅部分及び樹脂硬化物部分と、樹脂硬化物により埋まっていないポーラス部分とが分かれるように、得られた断面画像を2値化処理する。
(iv)2値化処理された断面画像から、導電体断面の全面積に対する樹脂硬化物により埋まっていないポーラス部分の面積の比率を求め、これを導電体の空孔率とする。
(v)硬化性樹脂組成物を含浸する前の銅焼結体の空孔率と、導電体の空孔率とを下記式(1)に代入することにより、導電体における樹脂硬化物の充填率を算出する。
導電体における樹脂硬化物の充填率(%)=[(B-A)/B]×100・・・式(1)
[式(1)中、Aは導電体の空孔率(%)を示し、Bは銅焼結体の空孔率(%)を示す。]
貫通孔に充填された導電体の空孔率を算出する場合には、上記(i)において、貫通孔内の導電体の中央部の断面を露出させる。導電体充填スルーホール基板の主面上に形成された導電体の空孔率を算出する場合には、上記(i)において、主面上の導電体の断面を露出させる。
この工程では、スルーホール基板40の主面上に形成された導電体35の少なくとも一部を除去することができる。導電体を除去する手段としては、化学的研磨、機械的研磨、化学的機械的研磨、フライカット処理及びプラズマ処理等が挙げられる。フライカット処理とは、サーフェースプレーナによる切削平坦化を意味する。
(貫通孔の導電体)
(a)貫通孔30の中央部C(孔長Lにおける中心且つそこでの孔径Dにおける中心)、を通り、基板の厚み方向に伸びる線L1と、導電体35の表面とが交わる点S3から深さ10μmまでの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(b)上記点S3から深さ10~20μmの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(c)上記点S3から深さ20~30μmの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(d)貫通孔30の中央部Cから、基板の厚み方向に±5μm及び基板の厚み方向と直交する方向に±5μmの範囲において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(基板の主面上の導電体)
(e)基板の主面に形成された導電体35の表面S4から深さ5μmまでの領域において、樹脂硬化物の充填率が、銅焼結体5のポーラス4の内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(f)基板の主面に形成された導電体35の表面S4から深さ10μmまでの領域において、樹脂硬化物の充填率が、銅焼結体5のポーラス4の内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(g)上記表面S4から深さ10~20μmの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(h)上記表面S4からの深さ20~30μmの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
レジスト形成工程では、図3(f)に示すように、スルーホール基板40の主面上に形成された導電体35上にエッチングレジスト8を形成する。
エッチング工程では、図4(g)に示すように、エッチングレジスト8により被覆されていない部分の導電体35をエッチングにより除去する。本実施形態においては、絶縁性基体1の両主面上に設けられた金属被膜2の一部がエッチングにより除去されている。
レジスト除去工程では、導電体35上に形成されたエッチングレジスト8を除去する。
図4(h)は、上述の実施形態に係る方法によって製造することができる導電体充填スルーホール基板の一実施形態を示す断面図である。図4(h)に示す導電体充填スルーホール基板52は、貫通孔30が設けられている絶縁性基体1を含み、両主面に貫通孔30が通じているスルーホール基板40と、貫通孔30を充填する導電体35とを備え、上記導電体35が、ポーラス構造を有する銅焼結体5と、銅焼結体5のポーラス4に充填された樹脂硬化物6とを含む。
(貫通孔の導電体)
(a)貫通孔30の中央部C(孔長Lにおける中心且つそこでの孔径Dにおける中心)、を通り、基板の厚み方向に伸びる線L1と、導電体35の表面とが交わる点S5から深さ10μmまでの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(b)上記点S5から深さ10~20μmの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(c)上記点S5から深さ20~30μmの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(d)貫通孔30の中央部Cから、基板の厚み方向に±5μm及び基板の厚み方向と直交する方向に±5μmの範囲において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(基板の主面上の導電体)
(e)基板の主面に形成された導電体35の表面S6から深さ5μmまでの領域において、樹脂硬化物の充填率が、銅焼結体5のポーラス4の内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(f)基板の主面に形成された導電体35の表面S6から深さ10μmまでの領域において、樹脂硬化物の充填率が、銅焼結体5のポーラス4の内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(g)上記表面S6から深さ10~20μmの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(h)上記表面S6からの深さ20~30μmの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
本実施形態の導電体充填スルーホール基板を用いて製造される半導体装置について図5を用いて具体的に説明する。図5は、本発明の半導体装置の一実施形態を示す模式断面図であり、TSV(Through-Silicon-Via)技術を用いた半導体装置である。図5(a)に示す半導体装置100は、インタポーザー基板25上の配線27と、導電体充填スルーホール基板51の導電体35とが直接接続されることにより、インタポーザー基板25と導電体充填スルーホール基板51とがフリップチップ接続されている。インタポーザー基板25と導電体充填スルーホール基板51との空隙には接着剤の硬化物20が隙間なく充填されており、封止されている。上記導電体充填スルーホール基板51におけるインタポーザー基板25と反対側の主面上には、導電体充填スルーホール基板51が繰り返し積層されている。導電体充填スルーホール基板51同士は、導電体35により接続されている。導電体充填スルーホール基板51同士の間の空隙には接着剤の硬化物20が隙間なく充填されており、封止されている。
(貫通孔の導電体)
(A)貫通孔30の中央部Cから、基板の厚み方向に±5μm及び基板の厚み方向と直交する方向に±5μmの範囲において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(B)貫通孔30の中央部C(孔長Lにおける中心且つそこでの孔径Dにおける中心)、を通り、基板の厚み方向に伸びる線L1と、絶縁性基板の主面を含む面S10とが交わる点S7から深さ10μmまでの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(C)上記点S7から深さ10~20μmの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
(D)上記点S7から深さ20~30μmの領域において、樹脂硬化物の充填率が、銅焼結体のポーラスの内部空間の体積の合計を基準として、80体積%以上、90体積%以上、又は95体積%以上であってよい。
本実施形態の導電体充填スルーホール基板の製造方法で用いられる、銅粒子を含む銅ペーストについて説明する。
[ノナン酸銅の合成]
水酸化銅(関東化学株式会社、特級)91.5g(0.94mol)に1-プロパノール(関東化学株式会社、特級)150mLを加えて撹拌し、これにノナン酸(関東化学株式会社、90%以上)370.9g(2.34mol)を加えた。得られた混合物を、セパラブルフラスコ中で90℃、30分間加熱撹拌した。得られた溶液を加熱したままろ過して未溶解物を除去した。その後放冷し、生成したノナン酸銅を吸引ろ過し、洗浄液が透明になるまでヘキサンで洗浄した。得られた粉体を50℃の防爆オーブンで3時間乾燥してノナン酸銅(II)を得た。収量は340g(収率96質量%)であった。
上記で得られたノナン酸銅(II)15.01g(0.040mol)と酢酸銅(II)無水物(関東化学株式会社、特級)7.21g(0.040mol)をセパラブルフラスコに入れ、1-プロパノール22mLとヘキシルアミン(東京化成工業株式会社、純度99%)32.1g(0.32mol)を添加し、オイルバス中で、80℃で加熱撹拌して溶解させた。氷浴に移し、内温が5℃になるまで冷却した後、ヒドラジン一水和物(関東化学株式会社、特級)7.72mL(0.16mol)を氷浴中で撹拌した。なお、銅:ヘキシルアミンのモル比は1:4である。次いで、オイルバス中で、90℃で加熱撹拌した。その際、発泡を伴う還元反応が進み、30分以内で反応が終了した。セパラブルフラスコの内壁が銅光沢を呈し、溶液が暗赤色に変化した。遠心分離を9000rpm(回転/分)で1分間実施して固体物を得た。固形物を更にヘキサン15mLで洗浄する工程を3回繰り返し、酸残渣を除去して、銅光沢を有する銅粒子の粉体(第2の銅粒子)を得た。
<実施例1~73>
下記に示す原料を表1~8に示す割合で混合して銅ペーストを調整した。
扁平 1.4μm:1100YP(三井金属鉱業株式会社製、平均粒径1.4μm(D50)、商品名)
扁平 3.1μm:1200YP(三井金属鉱業株式会社製、平均粒径3.1μm(D50)、商品名)
扁平 5.8μm:MA-C05KP(三井金属鉱業株式会社製、平均粒径5.8μm(D50)、商品名)
扁平 7.3μm:MA-C05KFD(三井金属鉱業株式会社製、平均粒径7.3μm(D50)、商品名)
球状 100nm:上記で合成した銅粒子
球状 250nm:CH0200(三井金属鉱業株式会社製、D50 250nm、商品名)
[その他]
ジエチレングリコール(富士フィルム和光純薬株式会社製)
第1の銅粒子として1100YP(三井金属鉱業株式会社製、平均粒径1.4μm(D50)、商品名)を70質量部、第2の銅粒子として上記で合成した銅粒子を30質量部、ジエチレングリコール(富士フィルム和光純薬株式会社製)を5質量部、樹脂成分を5質量部混合し、銅ペーストを調整した。樹脂成分としては、有機バインダーのアクリル樹脂と、有機溶剤のカルビトール及びテレピネオールの混合物(混合物におけるカルビトールとテレピネオールとの質量比が、カルビトール:テレピネオール=1:1)とを、1:2の質量比で混合したものを用いた。
<実施例1~73及び比較例1>
貫通孔を備え、両主面上及び貫通孔の壁面にチタン層、ニッケル層、銅層がこの順に形成されたシリコン基板をスルーホール基板として準備した。なお、シリコン基板の直径は6インチ、厚みは500μmである。シリコン基板の貫通孔の孔径を表1~8に示した。チタン層、ニッケル層、銅層は順次スパッタにより形成されている。
<実施例1~8、12~21、24~43、48~73及び比較例1>
調製した銅ペーストをシリコン基板の両主面上に金属ヘラにより塗布し、銅ペーストを貫通孔に充填した。塗布後、90℃にて10分間、大気中で銅ペーストを乾燥させた。乾燥後、シリコン基板には厚み30μmの銅ペースト層が形成されていた。
シリコン基板を加圧治具により加圧しなかったこと以外は、実施例1と同様にして銅焼結体充填スルーホール基板を得た。焼結後のシリコン基板の両主面上に形成された銅焼結体の厚みは、35μmであった。
焼結処理時に水素ガスに代えて窒素ガスを流したこと以外は、実施例1と同様にして銅焼結体充填スルーホール基板を得た。焼結後のシリコン基板の両主面上に形成された銅焼結体の厚みは、30μmであった。
昇温時間を10分間、225℃で60分間の条件で焼結処理したこと以外は、実施例1と同様にして銅焼結体充填スルーホール基板を得た。焼結後のシリコン基板の両主面上に形成された銅焼結体の厚みは、30μmであった。
<実施例1~73及び比較例1>
集束イオンビーム加工観察装置(日立ハイテクノロジーズ社製、商品名:MI4050)を用い、集束イオンビームによって銅焼結体充填スルーホール基板におけるシリコン基板の貫通孔の中央部の断面及びシリコン基板の主面上に設けられた銅焼結体の断面を露出させ、該断面を観察した。貫通孔の中央部の断面を観察する際には、貫通孔に充填された銅焼結体の中央部から、シリコン基板の厚み方向に±5μm及びシリコン基板の厚み方向と直交する方向に±5μmの範囲を観察した。シリコン基板の主面上に設けられた銅焼結体の断面を観察する際には、シリコン基板の主面上に形成された銅焼結体の表面から5μmまでの領域において、シリコン基板の厚み方向に10μm及びシリコン基板の厚み方向と直交する方向に10μmの範囲を観察した。
観察には、走査型電子顕微鏡(日立ハイテクノロジーズ社製、商品名:S-3700N)を用い、倍率は1万倍とし、銅焼結体の断面画像(約10μm角)を撮影した。観察箇所は5箇所とした。得られた断面画像を、画像解析ソフト(Adobe Photoshop(登録商標) Elements)を用いて、焼結銅部分とポーラス部分とが分かれるように2値化処理した。2値化処理した断面画像を図6に示した。5箇所の観察箇所それぞれについて、銅焼結体断面の全面積に対するポーラス部分の面積の比率を空孔率とした。5箇所の観察の空孔率の平均値を銅焼結体の空孔率とした。結果を表1~8に示す。
<実施例1~73>
下記に示す硬化性樹脂組成物をロールコーターにより銅焼結体充填スルーホール基板の片面に塗布した。次いで、銅焼結体充填スルーホール基板を容器内に配置し、該容器内をゲージ圧が100KPaとなるように吸引し、真空状態とした。真空状態で銅焼結体充填スルーホール基板を10分間保持し、その後、銅焼結体充填スルーホール基板を容器から取り出した。貫通孔の銅焼結体に硬化性樹脂組成物が含浸し、硬化性樹脂組成物が、貫通孔の銅焼結体の硬化性樹脂組成物を塗布した面とは反対の面にまで到達していることを確認した。銅焼結体充填スルーホール基板の硬化性樹脂組成物の塗布面に残った硬化性樹脂組成物をゴムヘラで除去した。次いで、硬化性樹脂組成物を塗布した面とは反対の面に、硬化性樹脂組成物をロールコーターにより塗布し、銅焼結体充填スルーホール基板の表面に残った硬化性樹脂組成物をゴムヘラにより極力除去した。
YDF-170(東都化成社製、ビスフェノールF型エポキシ樹脂の商品名、エポキシ当量=170):95質量部
2PZ-CN(四国化成社製、イミダゾール化合物の商品名):5質量部
樹脂含浸工程は行わなかった。
<実施例1~73>
銅焼結体に硬化性樹脂組成物を含浸させたスルーホール基板を、窒素雰囲気中、180℃で1時間保持することにより、導電体充填スルーホール基板を得た。
樹脂硬化工程は行わなかった。
<実施例1~73及び比較例1>
導電体充填スルーホール基板の両面に対して、導電体充填スルーホール基板の両面の銅焼結体の厚みが20μmとなるまで機械的研磨処理を行った。導電体充填スルーホール基板を貼り付ける試料台としては、セラミック製冶具(ケメット・ジャパン株式会社製)を用い、導電体充填スルーホール基板を試料台に貼り付けるための材料としては、アルコワックス(日化精工株式会社製)を用いた。また、研磨剤としては、DP-懸濁液P-3μm・1μm・1/4μm(ストルアス製)を順に用いた。
<実施例1~73及び比較例1>
機械的研磨処理を行った導電体充填スルーホール基板を厚さ方向に切断し、シリコン基板の貫通孔の中央部の断面及びシリコン基板の主面上に設けられた導電体の断面を集束イオンビームによって露出させ、これらの断面を観察した。シリコン基板の貫通孔の中央部の断面を観察する際には、貫通孔の中央部から、シリコン基板の厚み方向に±5μm及びシリコン基板の厚み方向と直交する方向に±5μmの範囲を観察した。シリコン基板の主面上に設けられた導電体の断面を観察する際には、シリコン基板の主面上に設けられた導電体の表面から5μmまでの領域において、シリコン基板の厚み方向に10μm及びシリコン基板の厚み方向と直交する方向に10μmの範囲を観察した。
集束イオンビーム加工観察装置は、(日立ハイテクノロジーズ社製、商品名:MI4050)を用いた。観察には、走査型電子顕微鏡(日立ハイテクノロジーズ社製、商品名:S-3700N)を用い、倍率は1万倍とし、導電体の断面画像(約10μm角)を撮影した。観察箇所は5箇所とした。得られた断面画像を、画像解析ソフト(Adobe Photoshop(登録商標) Elements)を用いて、焼結銅部分及び樹脂硬化物部分と、ポーラス部分における樹脂硬化物により埋まっていない空間とが分かれるように2値化処理した。5箇所の観察箇所それぞれについて、導電体断面の全面積に対するポーラス部分における樹脂硬化物により埋まっていない空間の面積の比率を求め、これを空孔率とした。5箇所の観察の空孔率の平均値を導電体の空孔率とした。銅焼結体の空孔率と、導電体の空孔率とを下記式(1)に代入することにより、導電体における樹脂硬化物の充填率を算出した。
導電体における樹脂硬化物の充填率(%)=[(B-A)/B]×100・・・式(1)
[式(1)中、Aは導電体の空孔率(%)を示し、Bは銅焼結体の空孔率(%)を示す。]
<実施例1~73及び比較例1>
機械的研磨処理を行った導電体充填スルーホール基板の両面の銅焼結体の表面に紫外線硬化型エッチングレジスト用ドライフィルムH-W425(日立化成工業株式会社製、商品名)をラミネータにて圧着した。その後、フォトマスクを合わせて配線パターンを露光し、レジスト現像-銅焼結体のエッチング-レジスト除去を経て、配線を形成し、図7に示す導電体充填スルーホール基板(試験片55)を得た。得られた導電体充填スルーホール基板(試験片55)は、貫通孔に充填された導電体が、基板表面に設けられた導電体(配線)により電気的に接続されている。
<実施例1~73及び比較例1>
導電体充填スルーホール基板(試験片55)の初期抵抗値として連結接続抵抗値を測定した。シリコン基板の貫通孔の孔径が20μmである場合には、貫通孔20個が連結した抵抗値を、シリコン基板の貫通孔の孔径が30μmである場合には、貫通孔30個が連結した抵抗値を、シリコン基板の貫通孔の孔径が50μmである場合には、貫通孔30個が連結した抵抗値を、シリコン基板の貫通孔の孔径が100μmである場合には、貫通孔100個が連結した抵抗値を、シリコン基板の貫通孔の孔径が200μmである場合には、貫通孔200個が連結した抵抗値をそれぞれ測定した。測定した連結接続抵抗値は、下記の基準により評価した。評価がB以上のものを良好と判断した。結果を表1~8に示す。
A:抵抗値が10mΩ未満
B:抵抗値が10mΩ以上、30mΩ未満
C:抵抗値が30mΩ以上、100mΩ未満
D:抵抗値が100mΩ以上、500mΩ未満
E:抵抗値が500mΩ以上
<実施例1~73及び比較例1>
導電体充填スルーホール基板(試験片55)を温度サイクル試験機(TSA-72SE-W、エスペック株式会社製)にセットし、低温側:-40℃、15分、室温:2分、高温側:125℃、15分、除霜サイクル:自動、サイクル数:50、100、300、500サイクルの条件で温度サイクル接続信頼性試験を実施した。シリコン基板の貫通孔の孔径が20μmである場合には、貫通孔20個が連結した抵抗値を、シリコン基板の貫通孔の孔径が30μmである場合には、貫通孔30個が連結した抵抗値を、シリコン基板の貫通孔の孔径が50μmである場合には、貫通孔30個が連結した抵抗値を、シリコン基板の貫通孔の孔径が100μmである場合には、貫通孔100個が連結した抵抗値を、シリコン基板の貫通孔の孔径が200μmである場合には、貫通孔200個が連結した抵抗値をそれぞれ測定した。測定した連結接続抵抗値は、下記の基準により評価した。温度サイクル試験500回後の評価がB以上のものを良好と判断した。結果を表1~8に示す。
A:抵抗変化率が初期抵抗値に対して1%未満
B:抵抗変化率が初期抵抗値に対して1%以上3%未満
C:抵抗変化率が初期抵抗値に対して3%以上5%未満
D:抵抗変化率が初期抵抗値に対して5%以上10%未満
E:抵抗変化率が初期抵抗値に対して10%以上20%未満
F:抵抗変化率が初期抵抗値に対して20%以上
<実施例1~73及び比較例1>
導電体充填スルーホール基板(試験片55)を目視で確認し、シリコン基板の割れの有無を確認した。割れがない場合を○、部分的にでも割れがあった場合を×として評価した。結果を表1~8に示す。
<実施例1~73及び比較例1>
導電体充填スルーホール基板(試験片55)の気密性を評価した。評価は、ヘリウムリークディテクター(LEYBOLD社製「UL200」)を用いて行った。具体的には、導電体充填スルーホール基板を治具にセットし、測定機のインレット圧が5Paになるまで真空引きを行い、インレット圧が5Paに到達した時点でHe加圧(0.1MPa)を30秒間行った後、リーク量を測定して、以下の基準で評価した。結果を表1~8に示す。
A:リーク量が1×10-11Pa・m3/sec未満
B:リーク量が1×10-11以上1×10-10Pa・m3/sec未満
C:リーク量が1×10-10以上1×10-9Pa・m3/sec未満
D:リーク量が1×10-9以上1×10-8Pa・m3/sec未満
E:リーク量が1×10-8以上1×10-6Pa・m3/sec未満
F:リーク量が1×10-6Pa・m3/sec以上。
<実施例1~73及び比較例1>
配線形成工程において2mm×2mmの配線パターンを形成したこと以外は同様にして得た導電体充填スルーホール基板に対して、先端部面積1mm2のスタッドピンをハンダにより垂直に接合し、試験片とした。その試験片を固定し、引張試験機のチャック部でスタッドピンを掴み、上昇速度50mm/分で垂直上方へ引っ張り、シリコン基板の主面上の銅焼結体がシリコン基板から剥離する時の破壊荷重を測定した。そして、得られた破壊荷重の測定値と、銅焼結層の破壊面積から、下記式を用いて密着強度を算出した。なお、測定値は10点の平均とし、以下の基準で評価した。結果を表1~8に示す。
A:密着強度(MPa)が50MPa以上
B:密着強度(MPa)が40MPa以上50MPa未満
C:密着強度(MPa)が30MPa以上40MPa未満
D:密着強度(MPa)が20MPa以上30MPa未満
E:密着強度(MPa)が5MPa以上20MPa未満
F:密着強度(MPa)が5MPa未満
<実施例1~73及び比較例1>
配線形成工程において2mm×2mmの配線パターンを5本形成したこと以外は同様にして得た導電体充填スルーホール基板を、光学顕微鏡により監察し、配線パターンにおいてクラック(長さ0.5mm以上)の有無を監察した。倍率は500倍とし、以下の基準で評価した。結果を表1~8に示す。
A:クラックの発生無し
B:クラックが1本以上、2本未満
C:クラックが2本以上、5本未満
D:クラックが5本以上、10本未満
E:クラックが10本以上、20本未満
F:クラックが20本以上
<実施例1~73及び比較例1>
シリコン基板上に形成した導電体の体積抵抗率を測定した。体積抵抗率は、4端針面抵抗測定器(三菱アナリテック社製、商品名:ロレスタGP)で測定した面抵抗値と、非接触表面・層断面形状計測システム(VertScan、株式会社菱化システム)で求めた膜厚とから計算した。結果を表1~8に示す。
Claims (18)
- 貫通孔が設けられている絶縁性基体を含み、両主面に前記貫通孔が通じているスルーホール基板を準備する準備工程と、
少なくとも前記貫通孔を充填するように、ポーラス構造を有する銅焼結体を形成する銅焼結体形成工程と、
前記銅焼結体に硬化性樹脂組成物を含浸する樹脂含浸工程と、
前記銅焼結体に含浸させた前記硬化性樹脂組成物を硬化することにより、ポーラスに樹脂硬化物が充填された前記銅焼結体を含んでなる導電体を形成する樹脂硬化工程と、
を備える、導電体充填スルーホール基板の製造方法。 - 前記導電体における樹脂硬化物の充填率が、前記ポーラスの内部空間の体積を基準として、80体積%以上である、請求項1に記載の方法。
- 前記銅焼結体の空孔率が、前記銅焼結体の体積を基準として、1~15体積%である、請求項1又は2に記載の方法。
- 前記銅焼結体形成工程において、前記銅焼結体を、前記スルーホール基板の主面上の少なくとも一部を被覆するように形成する、請求項1~3のいずれか一項に記載の方法。
- 前記スルーホール基板の主面上に形成された前記導電体の少なくとも一部を除去する導電体除去工程を更に備える、請求項4に記載の方法。
- 前記導電体除去工程における除去手段が、エッチング、機械的研磨及び化学的機械的研磨からなる群より選択される一種以上である、請求項5に記載の方法。
- 前記スルーホール基板が、少なくとも前記貫通孔の壁面に設けられた金属被膜を備える、請求項1~6のいずれか一項に記載の方法。
- 前記貫通孔の孔径Dに対する孔長Lの比L/Dが10以上である、請求項1~7のいずれか一項に記載の方法。
- 前記銅焼結体形成工程が、
前記スルーホール基板の前記貫通孔に銅粒子とを含む銅ペーストを充填する銅ペースト充填工程と、
前記銅ペーストを焼成して前記銅焼結体を形成する銅ペースト焼成工程と、
を有する、請求項1~8のいずれか一項に記載の方法。 - 前記銅ペーストが、前記銅粒子として、粒径が0.8μm以上である第1の銅粒子と、粒径が0.5μm以下である第2の銅粒子と、を含む、請求項9に記載の方法。
- 前記第1の銅粒子が扁平状である、請求項10に記載の方法。
- 前記銅ペーストを0.1MPa以上の加圧下で焼成する、請求項9~11のいずれか一項に記載の方法。
- 前記銅ペーストを窒素又は水素を含む雰囲気下で焼成する、請求項9~12のいずれか一項に記載の方法。
- 貫通孔が設けられている絶縁性基体を含み、両主面に前記貫通孔が通じているスルーホール基板と、前記貫通孔を充填する導電体と、を備え、
前記導電体が、ポーラス構造を有する銅焼結体と、前記銅焼結体のポーラスに充填された樹脂硬化物と、を含む、導電体充填スルーホール基板。 - 前記導電体における樹脂硬化物の充填率が、前記ポーラスの内部空間の体積を基準として、80体積%以上である、請求項14に記載の導電体充填スルーホール基板。
- 前記スルーホール基板が、少なくとも前記貫通孔の壁面に設けられた金属被膜を備える、請求項14又は15に記載の導電体充填スルーホール基板。
- 前記貫通孔の孔径Dに対する孔長Lの比L/Dが10以上である、請求項14~16のいずれか一項に記載の導電体充填スルーホール基板。
- 前記導電体が、前記スルーホール基板の主面上の少なくとも一部を被覆する、請求項14~17のいずれか一項に記載の導電体充填スルーホール基板。
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