WO2013099771A1

WO2013099771A1 - Prepreg, circuit board and semiconductor device

Info

Publication number: WO2013099771A1
Application number: PCT/JP2012/083125
Authority: WO
Inventors: 大輔北原; 孝幸馬塲; 飛澤　晃彦
Original assignee: 住友ベークライト株式会社
Priority date: 2011-12-29
Filing date: 2012-12-20
Publication date: 2013-07-04
Also published as: CN104024312A; TW201336923A; KR20140113665A

Abstract

This prepreg contains a fiber base and a resin composition that is impregnated into the base, and is characterized in that the resin composition has an ammonium ion concentration of 30 ppm or less and contains a thermosetting resin and a curing agent that contains a novolac phenol resin. Consequently, there can be provided a prepreg that is capable of preventing the occurrence of migration and is capable of producing a circuit board that has high electrical connection reliability. The present invention is also able to provide a circuit board that has high electrical connection reliability and a highly reliable semiconductor device which is provided with this circuit board. In this connection, the thermosetting resin is preferably an epoxy resin.

Description

Prepreg, circuit board and semiconductor device

The present invention relates to a prepreg, a circuit board, and a semiconductor device.

Electronic circuit often uses circuit boards on which electrical circuits are formed. When manufacturing this circuit board, a member called a prepreg in which a fiber base material such as a glass fiber base material is impregnated with a thermosetting resin and dried to obtain a semi-cured state is usually used. A copper clad laminate can be produced by heating and pressurizing one or more prepregs and a copper foil or the like. Furthermore, a circuit board can be obtained by processing the copper foil of the copper clad laminate to form an electric circuit including a plurality of wirings.

As such a prepreg, for example, a fiber base made of glass fiber or the like is impregnated with a varnish containing a thermosetting resin such as an epoxy resin or a polyimide resin and dried (for example, , See Patent Document 1).

In recent years, with the downsizing and thinning of electronic parts and electronic devices, circuit boards and the like used therefor are also required to be downsized and thinned. For this reason, it is necessary to form an electric circuit with a higher density pattern on the circuit board.

However, in a circuit board using a conventional prepreg, a phenomenon in which a part of the metal material constituting the electric circuit moves on the circuit board and the wiring of the adjacent electric circuit becomes conductive, so-called migration occurs. There is a problem such as. This causes a reduction in the electrical connection reliability of the circuit board.

JP 2004-216784 A

An object of the present invention includes a prepreg capable of preventing occurrence of migration and manufacturing a circuit board having high electrical connection reliability, a circuit board having high electrical connection reliability, and such a circuit board. Another object is to provide a highly reliable semiconductor device.

Such an object is achieved by the present inventions (1) to (11) below.
(1) a fiber substrate;
A resin composition impregnated in the fiber base material,
The said resin composition contains a thermosetting resin and the hardening | curing agent containing a novolak-type phenol resin, and ammonium ion concentration is 30 ppm or less, The prepreg characterized by the above-mentioned.

(2) The prepreg according to (1), wherein the ammonium ion concentration is 25 ppm or less.
(3) The prepreg according to (1), wherein the ammonium ion concentration is less than 15 ppm.

(4) The prepreg according to (1), wherein the thermosetting resin is an epoxy resin.
(5) The prepreg according to (4), wherein the epoxy resin is a bisphenol type epoxy resin or a derivative thereof.

(6) The prepreg according to (1) above, wherein a reaction rate of the resin composition in the prepreg is 50% or less.
(7) The prepreg according to (1), wherein the fiber base material is made of glass fiber.

(8) The prepreg according to (1), wherein the fiber base is subjected to a fiber opening process.
(9) The prepreg according to (1), wherein the fiber base material is not subjected to a fiber opening process.

(10) A circuit board comprising the prepreg according to (1).
(11) A semiconductor device comprising the circuit board according to (10).

According to the present invention, a phenomenon in which part of the metal material constituting the electric circuit moves on the circuit board and the wirings of adjacent electric circuits become conductive, so-called migration, is prevented, and electrical It is possible to provide a prepreg capable of manufacturing a circuit board with high connection reliability.
Further, according to the present invention, it is possible to provide a circuit board and a semiconductor device with high electrical connection reliability.

FIG. 1 is a longitudinal sectional view showing an embodiment of the prepreg of the present invention. FIG. 2 is a longitudinal sectional view showing an embodiment of the semiconductor device of the present invention and the circuit board of the present invention.

Hereinafter, the prepreg, the circuit board, and the semiconductor device of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

<Prepreg>
First, the prepreg of the present invention will be described.
The prepreg of the present invention has a fiber base material and a resin composition impregnated in the fiber base material. This prepreg is obtained by impregnating a fiber base material with a resin composition and molding (shaping) it into a sheet.

By the way, in a circuit board using a conventional prepreg, a phenomenon in which a part of the metal material constituting the electric circuit moves on the circuit board and the wiring of the adjacent electric circuit becomes conductive, so-called migration occurs. There is a problem such as. This causes a reduction in the electrical connection reliability of the circuit board.

Therefore, the present inventors, in view of the above problems, as a result of earnest investigation, as a resin composition to be impregnated into the fiber substrate, including a thermosetting resin and a curing agent containing a novolac type phenol resin, and It has been found that the occurrence of migration can be suppressed by using one having an ammonium ion concentration of 30 ppm or less.

Hereinafter, preferred embodiments of the prepreg of the present invention will be described in detail.
FIG. 1 is a longitudinal sectional view showing an embodiment of the prepreg of the present invention.
A prepreg 1 shown in FIG. 1 includes a sheet-like substrate (fiber substrate) 11 and a resin composition 12 impregnated in the sheet-like substrate 11.

<Sheet-like base material 11>
The sheet-like base material 11 is, for example, a glass fiber base material such as glass woven fabric, glass non-woven fabric, glass paper, woven fabric or non-woven fabric made of organic fibers such as paper (pulp), aramid, polyester, fluororesin, and metal fiber. Woven fabrics, nonwoven fabrics, mats and the like made of carbon fibers, mineral fibers, and the like. In addition, these base materials can be used alone, or a plurality of types can be mixed or laminated.

When a glass fiber base material is used as the sheet-like base material 11, the occurrence of migration can be more effectively prevented. Further, when an organic fiber base material (for example, organic fiber nonwoven fabric) is used as the sheet-like base material 11, via prepreg 1 or a circuit board manufactured using prepreg 1 can process vias by laser (via vias). (Ease of processing and processing accuracy) can be improved.

In addition, the sheet-like base material 11 is preferably a woven fabric obtained by braiding a bundle of fibers, particularly a bundle of longitudinal fibers and a bundle of transverse fibers. Such a sheet-like substrate 11 is easily impregnated with the resin composition 12 and, after the resin composition 12 is cured, the resin composition has an anchor effect due to the cured product entering the fiber texture. 12 and the sheet-like base material 11 can be firmly joined.

Note that the sheet-like base material 11 may be either one that has been subjected to fiber opening processing or one that has not been subjected to fiber opening processing. The term “opening process” refers to a process for flattening a bundle of fibers. When the sheet-like base material 11 is a woven fabric, adjacent fibers are arranged substantially without gaps in the warp yarn (bundle of warp fibers) and the weft yarn (bundle of weft fibers) by the fiber opening process. .

Here, when the sheet-like base material 11 is subjected to fiber opening processing, the impregnated resin composition 12 is less likely to drop off from the sheet-like base material 11 and the sheet-like base material 11 is impregnated with the resin composition 12. Can be maintained at a high level (impregnation of the resin composition 12 can be enhanced). As a result, it is possible to suppress generation of voids in the prepreg 1 that are also a cause of migration. Moreover, in the prepreg 1 or a circuit board manufactured using the prepreg 1, laser via processability can be further improved.

On the other hand, by omitting the opening process to the sheet-like base material 11, the manufacturing cost of the sheet-like base material 11 (prepreg 1) can be reduced and the mechanical strength of the prepreg 1 can be prevented from being lowered.

The sheet-like substrate 11 is impregnated with the resin composition 12. This resin composition 12 includes a thermosetting resin and a curing agent containing a novolac type phenol resin, and has an ammonium ion concentration of 30 ppm or less. The resin composition 12 will be described in detail later.

Further, the ammonium ion concentration contained in the prepreg 1 is preferably 25 ppm or less, more preferably 20 ppm or less, and even more preferably less than 15 ppm. Thereby, in the circuit board etc. manufactured using the prepreg 1, generation | occurrence | production of migration can be prevented more reliably and the electrical connection reliability of a circuit board etc. can be improved further.

Next, a method for manufacturing the prepreg 1 will be described.
The prepreg 1 is manufactured by preparing a resin varnish obtained by dissolving the resin composition 12 in a solvent, impregnating the resin varnish into the sheet-like base material 11, and then drying it.

The solvent used in the resin varnish desirably has good solubility in the resin composition 12, but a poor solvent may be used as long as it does not have an adverse effect. Solvents exhibiting good solubility include, for example, alcohols such as methanol and ethanol, toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene glycol, cellosolve System, carbitol system and the like.

Among these, as the solvent, an organic compound that does not contain a nitrogen atom in the chemical formula is preferable, and alcohols, methyl ethyl ketone, and toluene are particularly preferable. When an organic compound that does not contain a nitrogen atom in the chemical formula is used as the solvent, it does not become a source of ammonium ions, so that the ammonium ion concentration in the resin composition 12 can be easily reduced to 30 ppm or less.

The ratio of the solid content in the resin varnish is not particularly limited, but is preferably about 40 to 80% by mass, and more preferably about 50 to 70% by mass. Thereby, the impregnation property to the sheet-like base material 11 of a resin varnish can be improved more.

The resin varnish can be prepared, for example, in an atmosphere in which no nitrogen gas is present (for example, in an oxygen gas atmosphere or an argon gas atmosphere). Thereby, the ammonium ion concentration in the prepreg 1 can be easily reduced to 30 ppm or less.

Examples of the method of impregnating the sheet-like substrate 11 with the resin varnish include, for example, a method of immersing the sheet-like substrate 11 in the resin varnish, a method of applying the resin varnish to the sheet-like substrate 11 with various coaters, and a resin varnish by spraying. And the like, and the like. Among these, as a method for impregnating the sheet-like substrate 11 with the resin varnish, a method of immersing the sheet-like substrate 11 in the resin varnish is preferably used. According to this method, the impregnation property of the resin varnish with respect to the sheet-like base material 11 can be improved. In addition, when immersing the sheet-like base material 11 in a resin varnish, a normal impregnation coating equipment can be used.

The sheet-like base material 11 impregnated with the resin varnish can be made into the prepreg 1 by almost completely curing the resin varnish, but it is in an uncured state by drying the resin varnish to such an extent that it does not lead to curing. It can also be set as the prepreg 1, and also it can be set as the prepreg 1 by making it the state (hardened state) between hardening and uncured by hardening a resin varnish a little.

In this case, the reaction rate of the resin composition in the prepreg 1 is not particularly limited, but is preferably 50% or less, more preferably about 0.1 to 40%. Thereby, in addition to the above-mentioned effect, generation | occurrence | production of powder in the prepreg 1 can be prevented. In addition, migration can be more effectively prevented in a circuit board or the like manufactured using the prepreg 1.

In addition, this reaction rate can be calculated | required by differential scanning calorimetry (DSC). That is, by measuring the area of the exothermic peak due to the DSC reaction for both the unreacted resin composition 12 and the resin composition 12 in the prepreg 1, and substituting the measurement result into the following formula (A), The reaction rate can be determined. Note that the area of the exothermic peak is measured in a nitrogen atmosphere at a heating rate of 10 ° C./min.

Reaction rate (%) = (1-exothermic peak area of resin composition 12 in prepreg 1 / exothermic peak area of unreacted resin composition 12) × 100 (A)

In addition, the prepreg 1 including the resin composition 12 in an uncured or semi-cured state is obtained by laminating a metal foil and then curing the resin composition 12 to form a circuit laminate such as a copper clad laminate. Can be manufactured.

<Resin composition 12>
Next, the resin composition 12 will be described in detail.
The resin composition 12 includes a thermosetting resin and a curing agent containing a novolac type phenol resin, and has an ammonium ion concentration of 30 ppm or less.
The ammonium ion concentration can be measured as follows.
The resin composition 12 is immersed in pure water and extracted with hot water to obtain a test solution. By analyzing this test solution using an ion chromatograph, the ammonium ion concentration can be measured.

Hereinafter, each component which comprises the resin composition 12 is demonstrated in detail.
[Thermosetting resin]
The resin composition contains a thermosetting resin.

Examples of thermosetting resins include resins having triazine rings such as epoxy resins, urea (urea) resins, and melamine resins, unsaturated polyester resins, bismaleimide resins, polyurethane resins, diallyl phthalate resins, silicone resins, and benzoxazine rings. And a resin having a cyanate ester resin.

Among the above-mentioned, it is preferable to use an epoxy resin as the thermosetting resin. Thereby, in the circuit board manufactured using the prepreg 1, the occurrence of migration can be more effectively prevented, and the heat resistance of the prepreg 1 (circuit board) formed using the resin composition 12 can be reduced. Can be improved.

Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol E type epoxy resin, bisphenol M type epoxy resin, bisphenol P type epoxy resin, bisphenol Z type epoxy resin and the like. Type epoxy resins or derivatives thereof, novolak type epoxy resins such as phenol novolac type epoxy resins, cresol novolac type epoxy resins, arylalkylene type epoxy resins such as biphenyl type epoxy resins and biphenyl aralkyl type epoxy resins, naphthalene type epoxy resins, anthracene Type epoxy resin, phenoxy type epoxy resin, dicyclopentadiene type epoxy resin, norbornene type epoxy resin, adamantane Epoxy resins, such as epoxy resins and fluorene type epoxy resins. One of these epoxy resins may be used alone, or two or more of them may be used in combination.

Among these, the epoxy resin is preferably a bisphenol type epoxy resin or a derivative thereof. Bisphenol type epoxy resins or derivatives thereof are preferred because of their high reactivity with the novolak type phenol resin contained in the curing agent. Moreover, the bisphenol type epoxy resin or its derivative has a polarized part in its structure, and it is easy to adsorb ammonium ions to the part. For this reason, in the circuit board manufactured using the prepreg 1, the occurrence of migration can be more effectively prevented.

The weight average molecular weight of the epoxy resin is not particularly limited, but is preferably about 300 to 10,000, more preferably about 500 to 5,000. When a weight average molecular weight is less than the said lower limit, there exists a possibility that tackiness may arise in the hardened | cured material of the resin composition 12. On the other hand, when a weight average molecular weight exceeds the said upper limit, depending on the kind of sheet-like base material 11, etc., there exists a possibility that the adhesiveness and heat resistance with respect to the sheet-like base material 11 of the resin composition 12 may fall.

In the resin composition 12, the content of the thermosetting resin is not particularly limited, but is preferably about 40 to 60% by mass, and more preferably about 50% by mass of the entire resin composition 12. Thereby, the heat resistance of the prepreg 1 (circuit board) can be improved efficiently, and the occurrence of migration can be prevented in a circuit board manufactured using the prepreg 1.

[Curing agent]
The resin composition 12 includes a curing agent containing a novolac type phenol resin.
By including such a curing agent, crosslinking of the thermosetting resin is promoted, and the mechanical strength of the cured product of the resin composition 12 can be increased. Moreover, since novolak-type phenol resin does not become a generation factor of ammonium ion, generation | occurrence | production of migration can be effectively suppressed in the circuit board manufactured using the prepreg 1.

Examples of the novolak type phenol resin include phenol novolak resin, cresol novolak resin, bisphenol A novolak resin, and the like.
The weight average molecular weight of the novolac type phenol resin is not particularly limited, but is preferably about 400 to 18,000, more preferably about 500 to 15,000. Thereby, the crosslinking reaction of the thermosetting resin can be further promoted, and the mechanical strength of the prepreg 1 (circuit board) can be further increased.

In the resin composition 12, the content of the curing agent is not particularly limited, but is preferably about 0.5 to 50% by mass of the entire resin composition 12, and more preferably about 1 to 40% by mass. preferable. By making content of a hardening | curing agent in the said range, the adhesiveness with respect to the sheet-like base material 11 of the resin composition 12 improves especially.

In addition to the novolak type phenol resin, the curing agent is a resol type phenol resin, an aryl alkylene type phenol resin, a terpene modified phenol resin, another phenol resin such as a dicyclopentadiene type phenol resin, an aliphatic amine, an aromatic. An amine, dicyandiamide, a dihydrazide compound, an acid anhydride, and the like may be contained.

[Other ingredients]
The resin composition 12 may contain, for example, a curing accelerator, an inorganic filler, a coupling agent and the like in addition to the above components.

(Curing accelerator)
The resin composition 12 may contain a curing accelerator. By including a curing accelerator, crosslinking of the thermosetting resin is promoted, and the mechanical strength of the cured product (prepreg 1) of the resin composition 12 can be increased.

Examples of the curing accelerator include organic metal salts such as zinc naphthenate, cobalt naphthenate, tin octylate, cobalt octylate, bisacetylacetonate cobalt (II), trisacetylacetonate cobalt (III), triethylamine, triethylamine, and the like. Tertiary amines such as butylamine, diazabicyclo [2,2,2] octane, 2-phenyl-4-methylimidazole, 2-ethyl-4-ethylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4 Imidazoles such as methyl-5-hydroxyimidazole and 2-phenyl-4,5-dihydroxyimidazole, phenolic compounds such as phenol, bisphenol A and nonylphenol, organic acids such as acetic acid, benzoic acid, salicylic acid, paratoluenesulfonic acid, Triphenylphos Fin, phosphorus compounds such as tri-tolylphosphine and the like, or a mixture thereof.

In the resin composition 12, the content of the curing accelerator is not particularly limited, but is preferably about 0.1 to 5 parts by weight, preferably 0.15 to 3 parts per 100 parts by weight of the thermosetting resin. More preferably, it is about part by mass. By making content of a hardening accelerator into the said range, the adhesiveness with respect to the sheet-like base material 11 of the resin composition 12 improves especially.

(Inorganic filler)
Further, the resin composition 12 may contain an inorganic filler. Thereby, even if the prepreg 1 is thinned (thickness of 35 μm or less), sufficient strength can be secured. Furthermore, the low thermal expansion of the prepreg 1 can be improved, that is, the thermal expansion coefficient of the prepreg 1 can be suppressed low.

Examples of the inorganic filler include talc, alumina, glass, silica, mica, aluminum hydroxide, magnesium hydroxide and the like. Among these, as the inorganic filler, silica is preferable, and fused silica is more preferable. This is because fused silica has excellent low thermal expansion. Further, examples of the shape of the silica include a crushed shape and a spherical shape, but a spherical shape is preferable.

Therefore, spherical silica (particularly spherical fused silica) is preferably used as the inorganic filler. By using such spherical silica as an inorganic filler, the melt viscosity of the resin composition 12 can be reduced, and the impregnation property to the sheet-like base material 11 can be more reliably ensured. Depending on the purpose, other inorganic fillers may be used.

The average particle diameter of the inorganic filler is not particularly limited, but is preferably 0.01 to 5.0 μm, and more preferably 0.2 to 2.0 μm. If the average particle size of the inorganic filler is less than the lower limit, the viscosity of the resin composition 12 (resin varnish) increases, and thus the workability during the production of the prepreg 1 may be affected. When the average particle diameter of the inorganic filler exceeds the upper limit, a phenomenon such as sedimentation of the inorganic filler may occur in the resin varnish.
This average particle diameter can be measured by, for example, a laser diffraction / scattering particle size distribution analyzer (for example, LA-500 manufactured by HORIBA).

For these reasons, it is preferable to use spherical silica (especially spherical fused silica) having an average particle size of 5.0 μm or less as the inorganic filler, and spherical fused silica having an average particle size of 0.01 to 2.0 μm is preferably used. More preferably it is used. Thereby, the filling property to the sheet-like base material 11 of an inorganic filler can be improved.

The content of the inorganic filler is not particularly limited, but is preferably 2 to 70% by mass, more preferably 5 to 60% by mass, based on the entire resin composition 12. When the content of the inorganic filler is within the above range, particularly low thermal expansion and low water absorption can be imparted to the prepreg 1.

(Coupling agent)
Moreover, the resin composition 12 may contain a coupling agent.
The coupling agent improves the wettability of the interface between the thermosetting resin and the inorganic filler, thereby uniformly fixing the thermosetting resin and the inorganic filler to the sheet-like base material 11. Heat resistance, particularly solder heat resistance after moisture absorption can be improved.

Any coupling agent can be used as long as it is usually used. Specifically, an epoxy silane coupling agent, a cationic silane coupling agent, an amino silane coupling agent, a titanate coupling agent, and a silicone oil type coupling agent. It is preferable to use 1 or more types selected from among these. Thereby, the wettability of the interface of a thermosetting resin and an inorganic filler can be made high, and, thereby, the heat resistance of the prepreg 1 can be improved more.

The content of the coupling agent is not particularly limited because it depends on the surface area of the inorganic filler, but it is preferably 0.05 to 3 parts by mass, particularly 0.1 to 2 parts by mass with respect to 100 parts by mass of the inorganic filler. Is preferred. If the content of the coupling agent is less than the lower limit, the inorganic filler cannot be sufficiently covered with the coupling agent, and thus the effect of improving the heat resistance of the prepreg 1 may not be sufficiently obtained. On the other hand, when the content of the coupling agent exceeds the upper limit, the reaction of the thermosetting resin is affected, and the bending strength and the like of the circuit board manufactured using the prepreg 1 may be reduced.
In addition to the components described above, the resin composition 12 may contain additives such as an antifoaming agent and a leveling agent as necessary.

<Semiconductor devices and circuit boards>
The circuit board of the present invention is manufactured using the prepreg 1 described above. According to the present invention, occurrence of migration is prevented, and a circuit board with high electrical connection reliability can be obtained.

The semiconductor device of the present invention includes the circuit board of the present invention and a semiconductor element mounted thereon.
FIG. 2 is a longitudinal sectional view showing an embodiment of the semiconductor device of the present invention and the circuit board of the present invention.
A semiconductor device 4 shown in FIG. 2 includes a circuit board 3, a semiconductor element 41 mounted on the circuit board 3, and solder balls 42 bonded to the lower surface of the circuit board 3.

Among these, the circuit board 3 includes the insulating substrate 31 obtained from the prepreg 1 (the prepreg of the present invention), the resin layer 2 laminated on the upper surface and the lower surface of the insulating substrate 31, and the insulating substrate 31 and the resin layer. 2, between the resin layers 2 and between the resin layers 2 and the upper and lower surfaces of the resin layer 2, and conductive bumps 33 that penetrate the insulating substrate 31 and the resin layer 2 and are connected to the circuit pattern 32. have. That is, the circuit board 3 is composed of a multilayer printed wiring board.

The semiconductor element 41 is mounted so as to be electrically connected to a circuit pattern 32 (land) provided on the upper surface of the circuit board 3.
On the other hand, a solder ball 42 for BGA is bonded to a circuit pattern 32 (land) provided on the lower surface of the circuit board 3.
In addition, the resin layer 2 can be comprised with the resin composition 12 as mentioned above.

In such a semiconductor device 4, the occurrence of migration in the circuit pattern 32 is prevented, and a short circuit between adjacent circuit patterns 32 is prevented. As a result, the semiconductor device 4 has high electrical connection reliability. In addition, the semiconductor device 4 has excellent mechanical strength.

Next, a method for manufacturing the circuit board 3 will be described.
First, a resin varnish is applied to a metal foil and dried to produce a resin-coated metal foil.
Next, an electric circuit is formed on the metal foil of the resin-attached metal foil by various patterning methods (such as photolithography and etching).

Next, via holes are formed in the metal foil with resin and the prepreg 1 by laser processing or the like, and a gold plating process is applied to the via holes to form bumps.
Next, three layers of metal foil with resin are laminated on both surfaces of the prepreg 1 and heated and pressed using a flat plate press or the like. Thereby, the resin composition 12 hardens | cures and the circuit board 3 is obtained.

The heating conditions in the heat and pressure molding can be, for example, a temperature of 150 to 250 ° C. and a time of about 60 to 240 minutes. The pressurizing condition is, for example, a pressure of about 1 to 4 MPa.

The prepreg, the circuit board, and the semiconductor device of the present invention have been described above. However, the present invention is not limited to this, and for example, any components may be added to the circuit board or the semiconductor device. .

Next, specific examples of the present invention will be described.
[1] Production of prepreg (Example 1)
1. Preparation of varnish of resin composition In an autoclave, 28.1 parts by mass of brominated bisphenol A type epoxy resin (Mitsubishi Chemical Corporation, 5047, epoxy equivalent 560), bisphenol A type epoxy resin (Mitsubishi Chemical Corporation, 828) 20.0 parts by mass of epoxy equivalent 190), 16.3 parts by mass of phenol novolak resin (DIC, TD-2090, hydroxyl equivalent 105), and 0-phenyl-4-methylimidazole (manufactured by Shikoku Kasei) 0.03 part by weight, 0.8 part by weight of epoxy silane (manufactured by Shin-Etsu Silicone, KBM-403), 1.5 part by weight of fused silica (manufactured by Admatechs, SO-E2, average particle size 0.5 μm), Aluminum hydroxide (manufactured by Nippon Light Metal Co., Ltd., BE-033, average particle size 3.0 μm) was added at 33.3 parts by mass.

Furthermore, 28.0 parts by mass of cyclohexanone was added to these components to obtain a mixture, and the inside of the autoclave was decompressed to 100 mmHg. Then, the mixture in an autoclave was stirred with the high-speed stirring apparatus with which an autoclave was equipped, and the varnish which contains 78 mass% of resin compositions on the solid content basis was obtained. The mixture was stirred by setting the inside of the autoclave to an argon gas atmosphere. The ammonium ion concentration in the resin composition measured in the following manner was below the detection limit (= 1.0 ppm).

(Measurement of ammonium ion concentration / eluted ion concentration in resin composition)
The solvent was volatilized from the varnish using a vacuum dryer, and 2.0 g of the residue was weighed to prepare a sample. This sample was put in an extraction container made of Teflon (“Teflon” is a registered trademark), and 40 g of ultrapure water was further added. Next, after the extraction container was shaken manually, it was put into a thermostat at 125 ° C., extracted with hot water for 20 hours continuously, allowed to cool to room temperature, and the liquid in the extraction container was used as a test solution. .

The test solution and the standard solution obtained above were introduced into an ion chromatograph (manufactured by DIONEX, ICS-2000 ion chromatograph), and each ion concentration was determined by a calibration curve method, and the eluted ion concentration from the sample was calculated. In addition, IonPacAS20 was used for the anion separation column, and IonPacCS12A was used for the cation separation column.

2. Manufacture of prepreg As a fiber base material, a glass woven fabric not subjected to fiber opening processing (thickness 0.16 mm, basis weight 208.0 g / m ² , air permeability 10.1 cm ³ / cm ² / sec, NANAYA GLASS FABRIC The above varnish is impregnated with respect to 208.0 parts by mass of the glass woven fabric so that the amount of the resin composition is 192.0 parts by mass, and then dried in a 180 ° C. drying oven. A prepreg was prepared by drying for 5 minutes. In addition, content of the resin composition in the obtained prepreg was 48.0 mass%.

As for the air permeability of the glass woven fabric, a sample was prepared by cutting the glass woven fabric into 200 mm × 500 mm, and this sample was set in a Frazier measuring instrument (AP-360S manufactured by Daiei Kagaku Co., Ltd.). It was determined by measuring the amount of air passing through 1 cm 2 of the sample per second at 27 cm.

(Example 2)
As a fiber base material, a glass woven fabric not subjected to fiber opening processing (thickness 0.18 mm, basis weight 220.0 g / m ² , air permeability 15.2 cm ³ / cm ² / sec, manufactured by NANAYA GLASS FABRIC) In the same manner as in Example 1, except that 220.0 parts by mass of the glass woven fabric was impregnated with the above varnish so as to be 180.0 parts by mass of the resin composition. A prepreg was produced. In addition, content of the resin composition in the obtained prepreg was 45.0 mass%.

(Example 3)
In the preparation of the varnish of the resin composition, instead of 16.3 parts by mass of phenol novolak resin (DIC, TD-2090, hydroxyl equivalent 105), bisphenol A novolac resin (DIC, VH-4170, hydroxyl equivalent 105) ) A prepreg was produced in the same manner as in Example 1 except that 16.3 parts by mass were added. The ammonium ion concentration in the resin composition was below the detection limit (= 1.0 ppm).

(Example 4)
In the preparation of the varnish of the resin composition, the addition amount of brominated bisphenol A type epoxy resin (Mitsubishi Chemical Co., Ltd., 5047, epoxy equivalent 560) was changed from 28.1 parts by mass to 31.1 parts by mass to obtain bisphenol A type In place of 20.0 parts by mass of epoxy resin (Mitsubishi Chemical Corporation, 828, epoxy equivalent 190), except that 17.0 parts by mass of bisphenol F type epoxy resin (DIC, 830S, epoxy equivalent 170) was added, A prepreg was produced in the same manner as in Example 1. The ammonium ion concentration in the resin composition was below the detection limit (= 1.0 ppm).

(Example 5)
As a fiber base material, a woven glass fabric (thickness 0.16 mm, basis weight 208.0 g / m ² , air permeability 5.1 cm ³ / cm ² / sec, manufactured by Nittobo Macao Co., Ltd.) is used as a fiber base material A prepreg was produced in the same manner as in Example 1 except that.

(Comparative Example 1)
In the preparation of the varnish of the resin composition, the addition amount of bisphenol A type epoxy resin (Mitsubishi Chemical Co., Ltd., 828, epoxy equivalent 190) into the autoclave was changed from 20.0 parts by mass to 35.9 parts by mass. A prepreg was produced in the same manner as in Example 1 except that the addition amount of -phenyl-4-methylimidazole (manufactured by Shikoku Kasei Co., Ltd.) into the autoclave was changed from 0.03 parts by mass to 0.5 parts by mass. The ammonium ion concentration in the resin composition was 15 ppm.

(Comparative Example 2)
1. Preparation of Varnish of Resin Composition In an autoclave, 36.4 parts by mass of brominated bisphenol A type epoxy resin (Mitsubishi Chemical Corporation, 5047, epoxy equivalent 560), bisphenol A type epoxy resin (Mitsubishi Chemical Corporation, 828) 25.9 parts by mass of epoxy equivalent 190), 2.1 parts by mass of dicyandiamide (produced by DEGUSA, DICYANEDIAMIDE, curing agent equivalent 21), and 0.03 parts by mass of 2-phenyl-4-methylimidazole (produced by Shikoku Chemicals) Parts, 0.8 parts by mass of epoxy silane (manufactured by Shin-Etsu Silicone, KBM-403), 1.5 parts by mass of fused silica (manufactured by Admatechs, SO-E2, average particle size 0.5 μm), aluminum hydroxide (Manufactured by Nippon Light Metal Co., Ltd., BE-033, average particle size 3.0 μm) was added at 33.3 parts by mass.

Furthermore, 28.0 parts by mass of cyclohexanone was added to these components to obtain a mixture, and the inside of the autoclave was decompressed to 100 mmHg. Then, the mixture in an autoclave was stirred with the high-speed stirring apparatus with which an autoclave was equipped, and the varnish which contains 78 mass% of resin compositions on the solid content basis was obtained. The ammonium ion concentration in the resin composition was 85 ppm.

2. Manufacture of prepreg As a fiber base material, a woven glass fabric (thickness 0.16 mm, basis weight 208.0 g / m ² , air permeability 5.1 cm ³ / cm ² / sec, manufactured by Nittobo Macao Co., Ltd.) ) Is impregnated with 208.0 parts by mass of the glass woven fabric so that the above-mentioned varnish is impregnated to 192.0 parts by mass of the resin composition, and then 5 in a drying oven at 180 ° C. The prepreg was prepared by drying for a minute. In addition, content of the resin composition in the obtained prepreg was 48.0 mass%.

(Comparative Example 3)
As a fiber base material, a glass woven fabric not subjected to fiber opening processing (thickness 0.16 mm, basis weight 208.0 g / m ² , air permeability 10.1 cm ³ / cm ² / sec, manufactured by NANAYA GLASS FABRIC) A prepreg was produced in the same manner as in Comparative Example 2 except that was used.

In addition, Table 1 shows the compounding ratios of the resin compositions in each Example and Comparative Example. Moreover, the reaction rate of the resin composition in the prepreg obtained by each Example and the comparative example was 50% or less.

[2] Manufacture of printed wiring board (circuit board) Manufacture of laminates Four prepregs obtained in each example and comparative example were stacked, and 18 μm thick electrolytic copper foil (manufactured by Furukawa Circuit Foil Co., Ltd., GTSMP) was stacked at a pressure of 4 MPa and a temperature of 200 ° C. Heat pressing was performed for 180 minutes. This obtained the double-sided copper clad laminated board of thickness 0.8mm.

2. Manufacture of printed wiring board After performing through-hole processing on the double-sided copper-clad laminate obtained above using a 65 μm drill bit, a swelling solution at 70 ° C. (Swelling Dip Securigant P, manufactured by Atotech Japan) For 5 minutes, and further immersed in an aqueous solution of potassium permanganate at 80 ° C. (Atotech Japan Co., Ltd., Concentrate Compact CP) for 15 minutes, followed by neutralization and desmear treatment in the through hole.

Next, after the surface of the electrolytic copper foil was etched by about 1 μm by flash etching, an electroless copper plating layer was formed with a thickness of 0.5 μm. Thereafter, a resist layer for electrolytic copper plating was formed on the electroless copper plating layer with a thickness of 18 μm, and after forming an electrolytic copper plating layer having a predetermined pattern, it was post-cured by heating at a temperature of 200 ° C. for 60 minutes. Next, after removing the resist layer for electrolytic copper plating, the entire surface including the electroless copper plated layer and the electrolytic copper plated layer was flash etched to form a circuit having a pattern of L / S = 75/75 μm. Finally, a solder resist (PSR4000 / AUS308 manufactured by Taiyo Ink Co., Ltd.) was formed to a thickness of 20 μm on the surface of this circuit to obtain a double-sided printed wiring board.

[3] Evaluation of laminate (prepreg) (1) Ammonium ion concentration / eluted ion concentration in prepreg The copper foil on the front and back of the double-sided copper-clad laminate obtained above is peeled off and cut to 1 × 1 mm to obtain a liquid A powder sample was obtained by freeze grinding in nitrogen. From this powder sample, 2.0 g was weighed and placed in an extraction container made of Teflon ("Teflon" is a registered trademark), and 40 g of ultrapure water was further added. Next, after the extraction container was shaken manually, it was put into a thermostat at 125 ° C., extracted with hot water for 20 hours continuously, allowed to cool to room temperature, and the liquid in the extraction container was used as a test solution. .

(2) Mechanical strength The copper foil of the front and back of the double-sided copper clad laminate obtained above was peeled off and cut into 60 × 10 mm to obtain test pieces. A 20-g weight was attached to the position of 57 mm of this test piece, and it processed in the atmosphere of 150 degreeC. After 15 minutes, the amount of deflection of the test piece was measured, and the creep resistance was evaluated to obtain an index of mechanical strength. Each code is as follows.

[Evaluation criteria]
A: Deflection amount is less than 5 mm B: Deflection amount is 5 mm or more

[4] Evaluation of Printed Wiring Board (1) Solder Heat Resistance Each printed wiring board obtained as described above was cut into 50 mm × 50 mm with a grinder saw to obtain a test piece. After this test piece was treated at 85 ° C. and 85% for 96 hours, the test piece was immersed in a solder bath at 260 ° C. for 30 seconds. Then, the presence or absence of abnormality in the appearance of the test piece was examined.

[Evaluation criteria]
A: No abnormality (no problem)
B: Swelling (there is a swelling part as a whole)

(2) Migration resistance The insulation resistance was measured in a state where a voltage of 32 V was applied to the through-hole portion of each printed wiring board obtained as described above under the conditions of 85 ° C. and 85%. The separation distance between the wall of the through hole and the wall of the through hole was 0.35 μm. Here, the case where the insulation was reduced to 5.0 MΩ or less was defined as “insulation reduction”, and the migration resistance was evaluated based on the time until this “insulation reduction”.

[Evaluation criteria]
A: There is no “decrease in insulation” even after 1500 hours or more. B: “Insulation drop” occurs between 1000 hours and less than 1500 hours. C: “Insulation drop” occurs between 500 hours and less than 1000 hours. D: Less than 500 hours. "Insulation degradation"

(3) Connection reliability With respect to the through-hole portion of each printed wiring board obtained as described above, an operation of holding at −50 ° C. for 10 minutes and holding at 125 ° C. for 10 minutes is one cycle. (TC) A test was conducted. After 1000 cycles of the TC test, the through hole portion was evaluated for the presence of disconnection failure.

[Evaluation criteria]
A: No disconnection failure (no problem)
B: Disconnection failure (problem)
The evaluation results are shown in Table 1.

As is clear from Table 1, the occurrence of migration was suppressed in the printed wiring board using the prepreg of the present invention. On the other hand, satisfactory results were not obtained in the comparative example. In addition, the mechanical strength of the printed wiring board showed the tendency to improve by omitting the opening process with respect to the glass woven fabric.

According to the present invention, when the ammonium ion concentration in the resin composition is 30 ppm or less, it is possible to obtain a prepreg capable of preventing the occurrence of migration and manufacturing a circuit board having high electrical connection reliability. Further, if such a prepreg is used, a circuit board and a semiconductor device having high electrical connection reliability can be obtained. Therefore, the present invention has industrial applicability.

Claims

A fiber substrate;
A resin composition impregnated in the fiber base material,
The said resin composition contains a thermosetting resin and the hardening | curing agent containing a novolak-type phenol resin, and ammonium ion concentration is 30 ppm or less, The prepreg characterized by the above-mentioned.
The prepreg according to claim 1, wherein the ammonium ion concentration is 25 ppm or less.
The prepreg according to claim 1, wherein the ammonium ion concentration is less than 15 ppm.
The prepreg according to claim 1, wherein the thermosetting resin is an epoxy resin.
The prepreg according to claim 4, wherein the epoxy resin is a bisphenol type epoxy resin or a derivative thereof.
The prepreg according to claim 1, wherein a reaction rate of the resin composition in the prepreg is 50% or less.
The prepreg according to claim 1, wherein the fiber substrate is made of glass fiber.
The prepreg according to claim 1, wherein the fiber base material is subjected to a fiber opening process.
The prepreg according to claim 1, wherein the fiber base material is not subjected to a fiber opening process.
A circuit board comprising the prepreg according to claim 1.
A semiconductor device comprising the circuit board according to claim 10.