JP2011210794A - Insulating substrate, method of manufacturing the same, printed-wiring board, and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed-wiring board having an excellent plating burying property in a through-hole and having a superior long-term connection reliability in an insulating substrate corresponding to the reduction of the diameter, thinning or aspect ratio enhancing of the printed-wiring board, and also to provide the method of manufacturing the insulating substrate and a semiconductor device.SOLUTION: The insulating substrate 21 is used for a printed-wiring board. The insulating substrate 21 includes the through-hole 41 while the through-hole 41 has the minimum diameter at a fixed depth place from one surface side of the insulating substrate 21 to the other surface side of the insulating substrate. In the insulating substrate, the diameter of the through-hole 41 is reduced towards the fixed depth place from one surface sides of the insulating substrate 21, and the diameter of the through-hole 41 is enlarged towards the other surface sides of the insulating substrate 21 from the fixed depth place in this case.

Description

  The present invention relates to an insulating substrate, a method for manufacturing the insulating substrate, a printed wiring board, and a semiconductor device.

  In recent years, electronic devices such as mobile phones, personal computers, videos, game machines, etc. have been used with higher density, thinner and smaller parts, and the wiring density of printed wiring boards, etc. on which they are mounted has also increased. Is required. In addition, the above printed wiring board is generally provided with a minute through hole such as a blind via hole or a through hole in an insulating substrate, and the wiring between the layers is electrically connected by the metal deposited in the minute through hole. ing.

  However, as the density of wiring increases, through holes and blind via holes used for interlayer connection of double-sided or multilayer printed wiring boards are also required to have smaller diameters and higher aspect ratios (for example, patents). Reference 1).

  Although electrical conduction can be achieved by plating the above-described blind via hole or through hole, it is required to fill the blind via hole or through hole with plating. However, since the printed wiring board has a smaller diameter, thinner thickness, and higher aspect ratio, there is a possibility that air bubbles may be taken into the plating without the formation of uniform plating without blind via holes or through holes embedded by plating. Was not enough.

JP 2008-004800 A

  The present invention has been made in view of the above circumstances, and is a laminate and a method for manufacturing a laminate corresponding to a reduction in diameter, thickness, or increase in aspect of a printed wiring board. It is an object of the present invention to provide a printed wiring board and a semiconductor device excellent in long-term connection reliability.

An insulating substrate according to the present invention is an insulating substrate used for a printed wiring board,
The insulating substrate has a through hole, and the through hole has a minimum diameter at a predetermined depth position from one surface side of the insulating substrate to the other surface side of the insulating substrate.
The through hole is reduced in diameter from one surface side of the insulating substrate toward the predetermined depth position, and is increased in diameter from the predetermined depth position toward the other surface side of the insulating substrate. .

  According to this insulating substrate, the through hole has a minimum diameter at a predetermined depth position from one surface side of the insulating substrate to the other surface side of the insulating substrate, and the through hole is formed of the insulating substrate. The diameter is reduced from one surface side of the substrate toward the predetermined depth position, and the diameter is increased from the predetermined depth position toward the other surface side of the insulating substrate. As a result, the hole diameter is reduced in the through-hole of the insulating substrate and has a constricted shape. Therefore, when plating is formed in the through-hole, first, contact between the platings grown from the wall surface of the through-hole in the constricted portion occurs. Begins embedding. Subsequently, the plating grows toward the surface on each side by continuing the plating. Since the diameter of the through-hole is increased in the direction in which plating grows, an insulating substrate that can provide a printed wiring board having excellent embedding properties without embedding bubbles during the growth can be obtained.

  Further, a ratio (d1) / (d2) between the diameter (d2) of the through hole provided on one surface side of the insulating substrate and the minimum diameter (d1) of the through hole provided at a predetermined depth position. May be 0.5 to 0.9. Further, when the thickness of the insulating substrate is (t1), (t1) is 200 μm or less, (d2) is 100 μm or less, and (t1) / (d2) is 2 or more. Good.

An insulating substrate manufacturing method according to the present invention is a method of manufacturing an insulating substrate used for a printed wiring board,
Disposing an insulating substrate and a reflecting member that reflects the laser on the other surface side of the insulating substrate;
A step of forming a through hole in the insulating substrate by performing laser drilling from one surface side of the insulating base;
Further continuing the laser irradiation toward the reflecting member,
The through hole has a minimum diameter at a predetermined depth position from one surface side of the insulating substrate to the other surface side of the insulating substrate, and the through hole is on one surface side of the insulating substrate. From the predetermined depth position, the diameter of the insulating substrate can be reduced, and the diameter of the insulating substrate can be increased from the predetermined depth position toward the other surface side of the insulating substrate.

  Since the reflection member that reflects the laser is disposed on the other surface side of the insulating substrate, when the laser is irradiated from one surface side of the insulating substrate, the laser that has passed through the insulating substrate is disposed on the other surface side. Since the laser beam is reflected by the reflecting member, the laser continues laser processing from the other surface side of the insulating substrate toward the one surface side. As a result, a through-hole whose diameter is reduced from one surface side of the insulating substrate toward the other surface side is combined with a through-hole whose diameter is reduced from the other surface side of the insulating substrate toward the one surface side. The through hole has a minimum diameter at a predetermined depth position from one surface side of the insulating substrate to the other surface side of the insulating substrate, and the through hole is one of the insulating substrates. It is possible to provide an insulating substrate manufacturing method in which the diameter is reduced from the surface side toward the predetermined depth position and the diameter is increased from the predetermined depth position toward the other surface side of the insulating substrate.

  Furthermore, a printed wiring board can be provided by processing a circuit on the insulating substrate.

  Furthermore, a semiconductor device in which a semiconductor element is mounted on the printed wiring board can be provided.

  According to the present invention, there is provided an insulating substrate and a method for manufacturing an insulating substrate corresponding to a reduction in the diameter, thickness, or aspect ratio of a printed wiring board, and excellent printed embedding in a through hole and excellent long-term connection reliability. A wiring board and a semiconductor device can be provided.

It is sectional drawing of the insulated substrate which shows one Embodiment of this invention. It is process sectional drawing which shows the manufacturing method of the insulated substrate of suitable embodiment of this invention. It is process sectional drawing which shows the manufacturing method of the insulated substrate of suitable embodiment of this invention. It is process sectional drawing of the plating embedding which shows a prior art example.

  Hereinafter, preferred embodiments of an insulating substrate, a method for manufacturing an insulating substrate, a printed wiring board, and a semiconductor device according to the present invention will be described in detail. In the description of the drawings, the same reference numerals are assigned to the same elements, and duplicate descriptions are omitted.

  First, the outline of the insulating substrate 21 of the present embodiment will be described with reference to FIG.

  The insulating substrate 21 of the present embodiment is an insulating substrate 21 used for a printed wiring board, and the insulating substrate 21 has a through hole 41. The through hole 41 has a minimum diameter (d1) at a predetermined depth position from one surface side of the insulating substrate 21 (upper surface in the drawing) to the other surface side (lower surface in the drawing) of the insulating substrate. Hereinafter, the upper surface in the drawing is also referred to as the upper surface, and the lower surface in the drawing is also referred to as the lower surface. The through hole 41 is reduced in diameter from the upper surface of the insulating substrate 21 toward a predetermined depth, and is expanded from the predetermined depth position toward the lower surface of the insulating substrate 21. In the present embodiment, the laminated body 20 in which the first metal layer 11 is laminated on the upper surface of the insulating substrate 21 and the second metal layer 12 is laminated on the lower surface is described as an embodiment.

  Next, when the diameter of the through hole 41 provided on the upper surface of the insulating substrate 21 is (d2), the ratio (d1) / (d2) of the minimum diameter (d1) to (d2) is 0.5 to It is preferably within the range of 0.9, and more preferably 0.5 to 0.8. Since the ratio of the diameter (d2) of the through hole 41 provided on the upper surface of the insulating substrate 21 to the minimum diameter (d1) is within this range, the plating embedding property of the through hole 41 in the plating embedding process is excellent. When (d1) / (d2) is smaller than 0.5, plating grown at the minimum diameter (d1) from the early stage of embedded plating comes into contact. After that, the plating grows and starts embedding. However, since the plating grows from the side wall surface for the enlarged diameter portion, the plating takes time, so if there is a non-uniform portion in the through hole 41, the plating is performed. A difference in the growth of the bubbles makes it easier to embrace bubbles. When (d1) / (d2) is larger than 0.9, the plating grows in other regions at the minimum diameter (d1) while the plating grows, and the embedding distance becomes longer. Therefore, it becomes easy to entrain bubbles during the growth. When the diameter (d2) of the through hole 41 provided on the upper surface of the insulating substrate 21 and the diameter of the through hole 41 provided on the lower surface of the insulating substrate 21 are (d3), (d2) ≧ (d3). May be.

  In addition, it is preferable that the minimum diameter (d1) of the through hole 41 provided at a predetermined depth position is provided at substantially the center in the thickness direction of the insulating substrate 21. Since the minimum diameter (d1) is provided at substantially the center in the thickness direction of the insulating substrate 21, when the through hole 41 is embedded by plating, the plating that has started to grow contacts the minimum diameter (d1) portion, and the insulating substrate Since the plating grows in a direction in which the diameter of the through-hole 41 expands to the upper surface and the lower surface of 21, the through-hole 41 can be filled with the plating without embedding bubbles during the growth.

  When the thickness of the insulating substrate 21 is (t1), (t1) is 200 μm or less, the diameter (d2) of the through hole 41 provided in the upper surface of the insulating substrate 21 is 100 μm or less, and (t1) / (D2) is applicable even if it is 0.6 or more, and is applicable because it is 2 or more. Even if the aspect ratio is large, for example, when the thickness of the insulating substrate is 1.6 mm and the diameter of the through hole 41 is 0.4 mm, the aspect ratio is 4, but the hole diameter is as large as 0.4 mm. Since the film thickness of the plating deposited on the wall surface is generally 20 to 50 μm, conventionally, the through-hole 41 is not buried by plating, and the through-hole 41 wall plating is deposited to form a metal layer on each surface side. The method of taking electrical continuity is taken. Therefore, even if the aspect ratio is large, there is little problem with the plating property. On the other hand, for example, when the hole diameter is 50 μm or less and the thickness of the insulating layer is 100 μm or less, the hole processing is difficult with a drill, and the hole processing is usually performed by laser processing. When laser processing is performed, the hole diameter tends to decrease in the direction in which the laser exits from the laser irradiation surface due to the nature of the processing. When the hole diameter is reduced from one surface to the other surface, when performing hole-filling through-hole plating, the plating that has started to grow first merges in the region of the metal layer on the lower surface, and then expands in diameter. And plating grows. At this time, since the distance at which the plating grows up to the upper surface is long, air bubbles are easily trapped during the growth. This is because the plating time until filling is long, so that the deposition of plating due to the current concentration on the peripheral portion of the through hole 41 becomes excessive, and it is considered that air bubbles are easily held. On the other hand, in the present invention, since the hole diameter is reduced in the through hole 41 of the insulating substrate 21 and has a constricted shape, when plating is formed in the through hole 41, first, the inner wall surface of the through hole 41 is plated. Then, the platings grown from the wall surface of the through hole 41 come into contact with each other at the constricted portion, and plating embedding into the through hole 41 starts. And by continuing the plating, the plating grows toward the surface on each side. However, since the through-hole 41 is expanded in the direction in which the plating grows, air bubbles are involved. Therefore, the through hole 41 can be embedded by plating, and a printed wiring board having excellent reliability can be obtained.

  Next, a method for manufacturing the insulating substrate 21 will be described.

  First, a laminated plate 20 is prepared in which the first metal layer 11 is laminated on the upper surface of the insulating substrate 21 and the second metal layer 12 is laminated on the lower surface (FIG. 2A). The thickness of the insulating substrate 21 is not particularly limited, but is preferably 20 μm to 200 μm, more preferably 30 μm to 100 μm.

  A reflecting member 50 is disposed on the lower surface of the laminated plate 20. In FIG. 3, the laminated plate 20 and the reflecting member 50 are schematically shown apart from each other. However, in consideration of the laser reflection efficiency, the reflecting member 50 may be disposed in contact with the laminated plate 20. preferable. By being disposed in contact with the laminated plate 20, the laser can form a through hole 41 from the upper surface to the lower surface, and can be reflected by the reflecting member to efficiently reflect the laser from the lower surface to the upper surface of the insulating substrate 21. It becomes. Moreover, it is preferable that the reflecting member 50 is mirror-finished from the viewpoint of the efficiency of reflection. The surface roughness Rz of the mirror-finished surface is preferably 4.0 μm or less, more preferably 2.0 μm or less. The surface roughness Rz is a 10-point average roughness defined by JIS B0601. Although it does not specifically limit as a reflecting member, For example, a metal plate is used preferably, Iron, aluminum, stainless steel, copper, nickel etc. are used preferably as a metal plate, Among these, copper is used more preferably.

A through hole 41 is formed in the laminated plate 20 by irradiating a laser from the upper surface (FIG. 2C). The hole diameter to be processed is preferably 100 μm or less, more preferably 50 μm or less. Examples of the laser include a CO ₂ laser processing machine, a UV laser processing machine, and an excimer laser processing machine, and a CO ₂ laser processing machine is preferable. The laser processing conditions are preferably a pulse width of 1 to 100 μm and a reference energy of 0.5 to 9.0 mJ, more preferably a pulse width of 1 to 20 μm and a reference energy of 1.0 to 3.0 mJ. The number of shots may be appropriately determined according to the thickness of the substrate. A copper foil having a thickness of 2 μm is laminated as the first metal layer 11 on the upper surface of the insulating substrate 21 which is a laser incident surface. Since the processing is performed by a conformal method, the first metal layer 11 is removed by etching in accordance with the hole diameter to be processed in the first metal layer 11 (FIG. 2B). Since the hole provided on the upper surface of the insulating substrate 21 is located at the incident portion, the maximum diameter of the through hole 41 is easily formed. While the insulating substrate 21 is disassembled, the bottom surface of the insulating substrate 21 is reached. At this time, the diameter of the through hole 41 decreases from the upper surface to the lower surface of the insulating substrate 21. The laser emitted from the lower surface reaches the reflecting member 50. The laser light reaching the reflecting member 50 is simultaneously reflected while processing the reflecting member, and is incident again from the lower surface of the insulating base material 21 to process the insulating base material 21. Laser light incident from the lower surface is processed while the through hole 41 is reduced in diameter toward the upper surface. For this reason, a shape is formed in which the through-hole 41 that is reduced in diameter from the upper surface to the lower surface and the through-hole 41 that is reduced in diameter from the lower surface toward the upper surface are formed. The through hole 41 has a minimum diameter (d1) at a predetermined depth position from the upper surface of the insulating substrate 21 to the lower surface of the insulating substrate. The through hole 41 is reduced in diameter from the upper surface of the insulating substrate 21 toward a predetermined depth, and is expanded from the predetermined depth position toward the lower surface of the insulating substrate 21.

As a result, as shown in FIG. 3A, the diameter of the through hole 41 of the insulating substrate 21 is reduced and has a constricted shape. Therefore, when plating is formed in the through hole 41, first, the through hole is formed. The plating begins to grow on the inner wall surface 41. Next, the platings grown from the through-hole wall surface in the constricted portion stick to each other and begin to be embedded (FIG. 3B). By continuing the plating, the plating grows toward the surface on each side. With respect to the direction in which plating grows, the diameter of the through hole 41 is increased, so that it is possible to provide an insulating substrate 21 that can provide a printed wiring board excellent in embeddability (FIG. 3C).
The position of the minimum diameter (d1) of the insulating substrate 21 can be adjusted by the laser irradiation time. This is because when the laser irradiation time is increased, the reflected laser is processed for a longer time from the lower surface of the insulating substrate, and as a result, the constricted position moves upward. The laser processing conditions can be appropriately selected so that the minimum diameter (d1) is formed substantially at the center with respect to the thickness direction of the insulating substrate. Therefore, it is suitable for the through hole 41 having a thick insulating layer and a small hole diameter, that is, a large aspect ratio.

Next, a method usually performed for clarifying the effect of the present invention will be described.
Usually, as shown in FIG. 4, the laminated plate 30 includes a single-layer insulating layer 25, a second metal layer 11 stacked on the upper surface of the single-layer insulating layer 25, and a second metal layer 12 stacked on the lower surface. The preparation performed by the conformal method is the same as that of the present embodiment. Laser processing is performed on the second metal layer 11 on the upper surface. Since the hole provided in the single-layer insulating layer 25 is located in the incident part, it forms the maximum diameter. Since it is a single layer insulating layer, the laser processing property during the processing does not change and penetrates the single layer insulating layer 25. Since there is no insulating layer that is easy to process even if laser processing proceeds, the single-layer insulating layer 25 is processed without expanding its diameter, and the diameter decreases from the second metal layer 11 on the upper surface toward the first metal layer 12 on the lower surface. A hole 40 is formed. Thereby, the through hole 40 is formed without forming a minimum diameter at a depth position from the upper surface to the lower surface of the single-layer insulating layer.
Since the through-hole 40 is unilaterally reduced in diameter from the second metal layer 11 on the upper surface of the single-layer insulating layer toward the first metal layer 12 on the lower surface, when hole filling through-hole plating is performed, The plating contacts in the vicinity of the interface with the first metal layer 12 on the lower surface of the single-layer insulating layer forming the minimum diameter (FIG. 4B). Next, the plating grows in the direction of expanding the diameter (FIG. 4C). At this time, since the distance at which the plating grows up to the upper surface is long, the bubbles 43 are easily involved in the growth process. This is because the plating time until filling is long, so that excessive plating precipitates due to current concentration in the peripheral portion of the through-hole 40, and air bubbles are easily taken in.

  Next, each component of the insulating substrate 21 of this embodiment will be described in detail.

The insulating substrate 21 may include an inorganic fiber base material. As an inorganic fiber base material, inorganic fiber base materials, such as glass fiber base materials, such as a glass fiber cloth and a glass non-woven cloth, or the fiber cloth or non-fiber cloth which contain inorganic compounds other than glass, for example are mention | raise | lifted. Among these, a glass woven fiber base material is preferable from the viewpoint of rigidity when used as a printed wiring board.
As a material constituting the resin of the insulating substrate 21, for example, a thermosetting resin and a curing agent are preferably included. As the thermosetting resin, an epoxy resin, a cyanate resin, a phenol resin, or the like can be used alone or in combination. Although it does not specifically limit as an epoxy resin, For example, bisphenol type epoxy resins, such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, etc. which are generally used for insulating substrates, phenol Novolak epoxy resins, novolak epoxy resins such as cresol novolac epoxy resins, brominated epoxy resins such as brominated bisphenol A epoxy resins, brominated phenol novolac epoxy resins, and heterocyclic epoxy resins such as triglycidyl isocyanate In addition, alicyclic epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin and the like can be mentioned. These can be used alone or in combination of two or more.
The cyanate resin can be obtained by, for example, reacting a halogenated cyanide compound with a phenol and prepolymerizing it by a method such as heating as necessary. Specific examples include bisphenol type cyanate resins such as novolac type cyanate resin, bisphenol A type cyanate resin, bisphenol E type cyanate resin, and tetramethylbisphenol F type cyanate resin. Among these, novolac type cyanate resin is preferable. Thereby, the heat resistance improvement by a crosslinking density increase and flame retardance, such as a resin composition, can be improved.
As the insulating substrate 21, the following resin film may be used. Examples of the resin film include polyimide resin films such as polyimide resin films, polyetherimide resin films, polyamideimide resin films, polyamide resin films such as polyamide resin films, and polyester resin films such as polyester resin films. . Among these, a polyimide resin film is mainly preferable. Thereby, especially an elasticity modulus and heat resistance can be improved.

  Although it does not specifically limit as a hardening | curing agent, For example, it is a hardening | curing agent which has an amino group generally used for insulating substrates, Comprising: Metaphenylenediamine, paraphenylenediamine, paraxylenediamine, 4,4'- Diaminodiphenylmethane, 4,4′-diaminodiphenylpropane, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylsulfone, 4,4′-diaminodicyclohexane, bis (4-aminophenyl) phenylmethane, 1, 5-Diaminonaphthalene, metaxylylenediamine, paraxylene naphthalene, 1,1-bis (4-aminophenyl) cyclohexane, dicyandiamide, diaminodiethyldimethylphenylmethane, and the like are used. In view of heat resistance, curability and the like, preferred curing agents are 4,4'-diaminodiphenylmethane, dicyandiamide, and diaminodiethyldimethylphenylmethane. Some of these may be used in combination.

  The insulating substrate 21 may contain an inorganic filler. For example, silicates such as talc, calcined clay, unfired clay, mica and glass, oxides such as titanium oxide, alumina, silica and fused silica, carbonates such as calcium carbonate, magnesium carbonate and hydrotalcite, aluminum hydroxide , Hydroxides such as magnesium hydroxide, calcium hydroxide, sulfates or sulfites such as barium sulfate, calcium sulfate, calcium sulfite, zinc borate, barium metaborate, aluminum borate, calcium borate, sodium borate, etc. Borate, aluminum nitride, boron nitride, silicon nitride, carbon nitride and other nitrides, strontium titanate, titanates such as barium titanate, and the like. As the inorganic filler, one of these can be used alone, or two or more can be used in combination. Among these, aluminum hydroxide and silica are particularly preferable, and fused silica (particularly spherical fused silica) is preferable in terms of excellent low thermal expansion. The shape is crushed and spherical, but in order to reduce the melt viscosity of the resin composition in order to ensure the impregnation property to the substrate, a usage method suitable for the purpose is used such as using spherical silica. The content of the inorganic filler is preferably 30 to 70 parts by weight, more preferably 40 to 60 parts by weight with respect to 100 parts by weight of the resin component.

  The average particle diameter of the inorganic filler is not particularly limited, but is preferably 0.05 to 10 μm, and particularly preferably 0.3 to 5 μm. This average particle diameter can be measured, for example, by a particle size distribution meter (manufactured by HORIBA, LA-500).

  The inorganic filler is not particularly limited, and an inorganic filler having a monodispersed average particle diameter can be used, and an inorganic filler having a polydispersed average particle diameter can be used. Furthermore, one or two or more inorganic fillers having an average particle size of monodisperse and / or polydisperse can be used in combination. The thickness of the insulating substrate 21 is preferably 30 μm to 200 μm, more preferably 40 μm to 120 μm.

  As the metal layers 11 and 12, when a metal thin film is used, a vacuum deposition method or a sputtering method is preferably used as a dry method, and an electrolytic plating method or an electroless plating method is used as a wet method. The film thickness is preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 2 μm. The metal species is preferably a single metal such as nickel, chromium, cobalt, molybdenum, vanadium, tungsten or copper, or an alloy thin film thereof. Moreover, when using ultra-thin metal foil, as a metal seed | species, stainless steel, nickel, aluminum, iron, copper etc. are used, and copper is used more suitably from etching property. The thickness of the metal foil is preferably 2 μm to 12 μm.

  Next, a printed wiring board obtained by processing the insulating substrate 21 will be described.

  As shown in FIG. 2, first, a laminate 20 is prepared in which copper foil having a thickness of 2 μm is laminated on the front and back surfaces as first and second metal layers 11 and 12 (FIG. 2A). Next, as shown in FIG. 2B, the second metal foil 11 on the upper surface of the insulating substrate 21 is removed by etching into a shape corresponding to the hole diameter. Next, the through-hole 41 is formed using a laser (FIG.2 (c)). Next, plating for filling the through holes 41 by plating is performed (FIG. 3). A desired wiring circuit was formed on the insulating substrate in which the through hole 41 was filled by using a photolithography method, and then the first and second metal layers 11 and 12 were etched to form a wiring circuit. Next, an insulating coating layer was formed while leaving a part of the wiring circuit, and a metal surface treatment was performed on the opening not covered with the insulating coating layer to obtain a printed wiring board.

  Next, a semiconductor device in which a semiconductor element is mounted on a printed wiring board will be described.

  A semiconductor device in which a semiconductor element is mounted on a printed wiring board is not particularly limited. For example, a semiconductor device in which a printed wiring board and a semiconductor element are connected by a bonding wire, or a printed wiring board and a semiconductor element are connected. A flip chip type semiconductor device connected through solder bumps is exemplified. An example of a flip chip type semiconductor device will be described below.

  In a flip chip type semiconductor device, a semiconductor element having a solder bump is mounted on a printed wiring board, and the printed wiring board and the semiconductor element are connected via the solder bump. A liquid sealing resin is filled between the printed wiring board and the semiconductor element to form a semiconductor device. The solder bump is preferably made of an alloy made of tin, lead, silver, copper, bismuth or the like. The method for connecting the semiconductor element and the printed wiring board is to align the connection electrode portion on the printed wiring board and the solder bump of the semiconductor element using a flip chip bonder, etc. In addition, the solder bumps are heated to the melting point or higher by using a heating device, and the printed wiring board and the solder bumps are connected by fusion bonding. In order to improve connection reliability, a metal layer having a relatively low melting point, such as solder paste, may be formed in advance on the connection electrode portion on the printed wiring board. Prior to this joining step, the connection reliability can be improved by applying flux to the solder bumps and / or the surface layer of the connection electrode portion on the printed wiring board.

  Hereinafter, although an example and a comparative example explain the present invention, the present invention is not limited to this.

Example 1
(1) As an insulating substrate, a copper foil having a thickness of 2 μm was laminated as a metal layer on both sides of a prepreg in which a glass fiber base was impregnated with an epoxy resin composition to obtain a laminated plate having a thickness of 100 μm. .

(2) A 45 μm through-hole was formed in the laminate using a carbon dioxide laser processing machine (manufactured by Mitsubishi Electric Corporation, 605GTXIII). Next, electroless plating and electrolytic plating were performed, and the through holes 41 were filled by plating. Next, circuit formation was performed by photolithography. Next, a solder resist (PSR4000 / AUS308 manufactured by Taiyo Ink Manufacture Co., Ltd.) is formed on each surface side, an opening is provided in a circuit portion on which a semiconductor element is mounted, nickel gold plating is applied to the opening, and 50 mm × The printed wiring board was obtained by cutting into a size of 50 mm.

(3) Manufacture of Semiconductor Device A semiconductor element (TEG chip, size 15 mm × 15 mm, thickness 0.8 mm) has a solder bump formed of a eutectic of Sn / Ag composition, and a circuit protective film formed of a positive photosensitive resin (Sumitomo). Bakelite CRC-8300) was used. In assembling the semiconductor device, first, a flux material was uniformly applied to the solder bumps by a transfer method, and then mounted on the package substrate by thermocompression bonding using a flip chip bonder device. Next, after solder bumps were melt-bonded in an IR reflow furnace, a liquid sealing resin (manufactured by Sumitomo Bakelite Co., Ltd., CRP-4152S) was filled and the liquid sealing resin was cured to obtain a semiconductor device. The liquid sealing resin was cured at a temperature of 150 ° C. for 120 minutes.

  Each configuration of the printed wiring board used for the created semiconductor device is as shown in Table 1. Each of the following evaluations was performed on the semiconductor devices obtained in the examples and comparative examples. Each evaluation is shown below together with the evaluation method. The obtained results are shown in Table 1.

1. Evaluation method (1) Plating embedding property Cross section polishing of the via portion was performed at n = 30, and the embedding property in the via was confirmed. The case where there was no void, the case where there was a micro void of 3 μm or less, and the case where a void larger than 3 μm was generated were marked as x.
(2) Temperature cycle continuity test As test conditions, a temperature cycle (−60 ° C. to 150 ° C.), a holding time of 10 minutes, and a temperature change time of 20 minutes were used. A continuity test was conducted until the cycle to confirm the continuity resistance.

  As is clear from Table 1, Examples 1 to 4 had good embedding properties. On the other hand, in Comparative Examples 1 and 2, voids occurred when the plating was embedded. In Examples 1 to 4, since the through hole has a constricted shape, when plating is formed in the through hole, the plating first grows on the inner wall surface of the through hole, and then the through hole is formed in the constricted portion. The plating grown from the wall surface sticks to each other and embedding begins. And it is thought that the bubble etc. did not get involved in the growth process of plating because plating grew toward the surface of each surface side by continuing plating. On the other hand, in Comparative Examples 1 and 2, the through-hole has a shape that decreases in diameter from one surface to the other surface, and since the distance that the plating grows to one surface side is long, bubbles are generated during the growth. It is considered that the entrapment is easy and the plating time until embedding is long, so that plating deposition due to current concentration on the peripheral portion of the through-hole is excessively generated and the bubbles are easily held. As a result of the temperature cycle test in the semiconductor device, those in which bubbles were embedded in the embedded plating were defective in 10 cycles even in the cycle test.

11 First metal layer 12 Second metal layer 20 Laminated plate 21 Insulating substrate 25 Single layer insulating layer 30 Laminated plate 40 Through hole 41 Through hole 43 Air bubble 50 Reflective member d1 Minimum diameter d2 Provided on one surface side of the insulating substrate Diameter d3 of the through hole Diameter t1 of the through hole provided on the other surface side of the insulating substrate Thickness of the insulating substrate

Claims (10)

An insulating substrate used for a printed wiring board,
The insulating substrate has a through hole,
The through hole has a minimum diameter at a predetermined depth position from one surface side of the insulating substrate to the other surface side of the insulating substrate;
The through hole is reduced in diameter from one surface side of the insulating substrate toward the predetermined depth position, and is increased in diameter from the predetermined depth position toward the other surface side of the insulating substrate. An insulating substrate characterized by that.   When the diameter of the through hole provided on one surface side of the insulating substrate is (d2) and the minimum diameter of the through hole provided at the predetermined depth position is (d1), (d1) / The insulating substrate according to claim 1, wherein (d2) is 0.5 to 0.9.   When the thickness of the insulating substrate is (t1), (t1) is 200 μm or less, the diameter (d2) of the through hole provided on one surface side of the insulating substrate is 100 μm or less, and (t1 The insulating substrate according to claim 1 or 2, wherein) / (d2) is 2 or more. A method of manufacturing an insulating substrate used for a printed wiring board,
Disposing an insulating substrate and a reflecting member that reflects the laser on the other surface side of the insulating substrate;
A step of forming a through hole in the insulating substrate by performing laser drilling from one surface side of the insulating base;
Further continuing the laser irradiation toward the reflecting member,
The through hole has a minimum diameter at a predetermined depth position from one surface side of the insulating substrate to the other surface side of the insulating substrate, and the through hole is on one surface side of the insulating substrate. The method of manufacturing an insulating substrate, wherein the diameter is reduced from the predetermined depth position toward the predetermined depth position, and the diameter is increased from the predetermined depth position toward the other surface side of the insulating substrate.   In the step of continuing further laser irradiation toward the reflecting member, the reflecting member reflects and reflects the laser from the other surface side of the insulating base material to the one surface side of the insulating base material. The manufacturing method of the insulated substrate of Claim 4 which laser-processes toward.   The method for manufacturing an insulating substrate according to claim 4, comprising a step of embedding the through hole by electroplating.   The method for manufacturing an insulating substrate according to claim 4, wherein the reflecting member is in contact with the other surface side of the insulating substrate.   The method for manufacturing an insulating substrate according to claim 4, wherein the reflecting member is a mirror-finished metal plate.   A printed wiring board obtained by processing a circuit on the insulating substrate according to claim 1.   A semiconductor device comprising a semiconductor element mounted on the printed wiring board according to claim 9.

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