JP5230059B2 - Prepreg, circuit board and semiconductor device - Google Patents

Description

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

In recent years, with the demand for higher functionality of electronic devices, etc., high density integration and high density mounting of electronic components are progressing. For this reason, printed wiring boards and the like for high-density mounting used for these are smaller and higher in density than conventional ones. As a measure for increasing the density of such printed wiring boards, build-up multilayer wiring boards are often used.
A general build-up multilayer wiring board is formed by laminating a core substrate with an insulating layer having a thickness of 100 μm or less formed only of a resin and a conductor layer.

  Even in such a build-up method, it is necessary to wire the circuit wiring with high density in order to cope with high-density mounting of electronic components. However, the circuit wiring pattern may be restricted due to warpage or the like generated on the substrate.

  Also, in multilayer wiring boards using the build-up method, the interlayer connection is made with fine vias, so the connection strength is reduced, and cracks and disconnections occur due to the stress generated between the insulating resin and the conductor layer when subjected to thermal shock. As a result, connection reliability may be reduced.

  In addition, when a build-up multilayer wiring board is used as a semiconductor element mounting substrate for mounting a semiconductor element, it is necessary to make bumps finer in order to cope with downsizing of the semiconductor element and an increase in the number of pins. However, connection reliability due to insufficient bonding strength between the semiconductor element and the substrate may be reduced due to the miniaturization of the bumps. Therefore, in order to obtain reliability of the bump connection portion, studies are being made to seal and reinforce the bump connection portion by filling the gap between the semiconductor element and the semiconductor element mounting substrate with an insulating resin called underfill. . However, since a process of filling and curing the underfill is required, there is a problem that the manufacturing process becomes complicated and the manufacturing cost increases (see Patent Document 1).

JP 2002-29383A

An object of the present invention is to provide a prepreg, a circuit board, and a semiconductor device using the prepreg capable of expanding the degree of freedom of circuit wiring patterns by improving the performance of the board.
Another object of the present invention is to provide a prepreg, a circuit board, and a semiconductor device using the prepreg that can improve connection reliability without complicating the manufacturing process.

Such an object is achieved by the present invention described in the following (1) to (6).
(1) and a cyanate resin, a resin composition containing an inorganic filler to a prepreg formed by impregnating a fiber base material, the content of the cyanate resin is a 5-5 0% by weight of the total resin composition The content of the inorganic filler is 50 to 80% by weight of the whole resin composition, the main fiber constituting the fiber base material is glass fiber, and the glass constituting the glass fiber is T glass or S. When the X and Y directions are set perpendicular to each other on the surface of the prepreg, the thermal expansion coefficient [Ax] in the X direction at 30 to 150 ° C. of the cured product obtained by curing the prepreg is 3 ppm / ° C. or higher 8 ppm / ° C. or less, and a prepreg, wherein the thermal expansion coefficient of the Y-direction [Ay] is not more than 3 ppm / ° C. or higher 8 ppm / ° C..
(2) The prepreg according to (1) above, wherein the fiber base material is a plain weave of warp and weft.
(3) The prepreg according to (1) or (2) above, wherein the X direction is a warp direction of fibers constituting the fiber base material, and the Y direction is a weft direction of fibers constituting the fiber base material. .
(4) Any one of the above (1) to (3), wherein an absolute value of a difference between the thermal expansion coefficient [Ax] in the X direction and the thermal expansion coefficient [Ay] in the Y direction is 5 ppm / ° C. or less. The prepreg according to Item.
(5) A circuit board having a cured product of the prepreg according to any one of (1) to (4).
(6) A semiconductor device, wherein a semiconductor element is mounted on the circuit board according to (5).

According to the present invention, it is possible to obtain a prepreg, a circuit board, and a semiconductor device using the prepreg capable of expanding the degree of freedom of circuit wiring patterns by improving the performance of the board.
Further, according to the present invention, it is possible to obtain a prepreg, a circuit board, and a semiconductor device using the prepreg that can improve connection reliability without complicating the manufacturing process.
In addition, when a specific glass fiber base material is used as the fiber base material, the coefficient of thermal expansion in the surface direction of the prepreg can be particularly reduced, thereby mounting a semiconductor element on a circuit board obtained using this prepreg. In this case, connection reliability can be improved.

Hereinafter, the prepreg, the circuit board, and the semiconductor device of the present invention will be described in detail.
The prepreg of the present invention is a prepreg obtained by impregnating a fiber base material with a resin composition containing a cyanate resin and / or a prepolymer thereof and an inorganic filler, wherein X is orthogonal to each other on the surface of the prepreg. When the Y direction is set, the thermal expansion coefficient [Ax] in the X direction at 30 to 150 ° C. of the cured product obtained by curing the prepreg is 10 ppm / ° C. or less, and the thermal expansion coefficient in the Y direction. [Ay] is 10 ppm / ° C. or less.
The circuit board of the present invention is composed of a cured product of the prepreg described above.
In the semiconductor device of the present invention, a semiconductor element is mounted on the circuit board described above.

  First, the prepreg will be described.

The prepreg of the present invention is formed by impregnating a fiber base material with a resin composition containing a cyanate resin (cyanate ester resin) and an inorganic filler. Thereby, it is excellent in heat resistance and dielectric characteristics.
The cyanate resin is meant to include both a cyanate resin and a prepolymer of the cyanate resin.
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 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. The novolak-type cyanate resin is considered to have a high proportion of benzene rings due to its structure and easily carbonize.

  As said novolak-type cyanate resin, what is shown, for example by Formula (I) can be used.

Although the repeating unit n of the novolak-type cyanate resin represented by the formula (I) is not particularly limited, 1 to 10 is preferable, and 2 to 7 is particularly preferable. When the repeating unit n is less than the lower limit, the novolak cyanate resin is easily crystallized, and the solubility in a general-purpose solvent is relatively lowered, which may make handling difficult. Moreover, when the repeating unit n exceeds the upper limit, the crosslink density becomes too high, which may cause a phenomenon such as a decrease in water resistance and a cured product becoming brittle.

Although the weight average molecular weight of the cyanate resin is not particularly limited, a weight average molecular weight of 500 to 4,500 is preferable, and 600 to 3,000 is particularly preferable. When the prepreg is produced when the weight average molecular weight is less than the lower limit, tackiness may occur, and when the prepregs come into contact with each other, they may adhere to each other or transfer of the resin may occur. Further, when the weight average molecular weight exceeds the above-described actual value, the reaction becomes too fast, and when it is a printed wiring board, molding failure may occur or the interlayer peel strength may be lowered.
The weight average molecular weight of the cyanate resin or the like can be measured by, for example, GPC.

  Although content of the said cyanate resin is not specifically limited, 5 to 60 weight% of the whole resin composition is preferable, and 10 to 50 weight% is especially preferable. If the content is less than the lower limit value, the heat resistance and the effect of low thermal expansion may be reduced, and if the content exceeds the upper limit value, the crosslink density increases and the free volume increases, which may reduce the moisture resistance.

In the prepreg of the present invention, an inorganic filler is used. Thereby, low thermal expansion and improvement of flame retardance can be achieved.
Moreover, the elasticity modulus of a circuit board can be improved especially by the combination of cyanate resin (especially novolak-type cyanate resin) mentioned above and an inorganic filler.

  Examples of the inorganic filler include talc, alumina, glass, silica, mica and the like. Among these, silica is preferable, and fused silica (particularly spherical fused silica) is preferable in that it has 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 of the fiber substrate, a method of use that suits the purpose, such as using spherical silica, is adopted. .

  The average particle diameter of the inorganic filler is not particularly limited, but is preferably 0.01 to 5.0 μm, particularly preferably 0.2 to 2.0 μm. If the particle size of the inorganic filler is less than the lower limit, the viscosity of the varnish becomes high, which may affect the workability during prepreg production. When the upper limit is exceeded, phenomena such as sedimentation of the inorganic filler may occur in the varnish.

  Furthermore, spherical silica (especially spherical fused silica) having an average particle size of 5.0 μm or less is preferable, and spherical fused silica having an average particle size of 0.01 to 2.0 μm is particularly preferable. Thereby, the filling property of an inorganic filler can be improved.

Although content of the said inorganic filler is not specifically limited, 50 to 80 weight% of the whole resin composition is preferable, and 60 to 70 weight% is especially preferable. If the content is within the above range, low thermal expansion,
Low water absorption can be achieved.

  The resin composition is not particularly limited, but an epoxy resin is preferably used. Examples of the epoxy resin include phenol novolac type epoxy resins, bisphenol type epoxy resins, naphthalene type epoxy resins, arylalkylene type epoxy resins and the like. Among these, aryl alkylene type epoxy resins are preferable. Thereby, moisture absorption solder heat resistance can be improved.

  The arylalkylene-type epoxy resin refers to an epoxy resin having one or more arylalkylene groups in a repeating unit. For example, a xylylene type epoxy resin, a biphenyl dimethylene type epoxy resin, etc. are mentioned. Among these, a biphenyl dimethylene type epoxy resin is preferable. The biphenyl dimethylene type epoxy resin can be represented by, for example, the formula (II).

The repeating unit n of the biphenyldimethylene type epoxy resin represented by the formula (II) is not particularly limited, but 1 to 10 is preferable, and 2 to 5 is particularly preferable. When the repeating unit n is less than the lower limit, the biphenyldimethylene type epoxy resin is easily crystallized, and the solubility in a general-purpose solvent is relatively lowered, which may make handling difficult. On the other hand, if the repeating unit n exceeds the upper limit, the fluidity of the resin is lowered, which may cause molding defects.

  Furthermore, when printed wiring boards are produced using a combination of the above-mentioned cyanate resin (especially novolac-type cyanate resin), phenol resin and arylalkylene-type epoxy resin (especially biphenyldimethylene-type epoxy resin), particularly excellent dimensional stability Sex can be obtained.

  Although content of the said epoxy resin is not specifically limited, 1 to 55 weight% of the whole resin composition is preferable, and 2 to 40 weight% is especially preferable. If the content is less than the lower limit, the reactivity of the cyanate resin may decrease, or the moisture resistance of the product obtained may decrease, and if the content exceeds the upper limit, the heat resistance may decrease.

The weight average molecular weight of the epoxy resin is not particularly limited, but a weight average molecular weight of 500 to 20,000 is preferable, and 800 to 15,000 is particularly preferable. When the weight average molecular weight is less than the lower limit value, tackiness may occur in the prepreg, and when the upper limit value is exceeded, the impregnation property to the base material may be reduced during preparation of the prepreg, and a uniform product may not be obtained. is there.
The weight average molecular weight of the epoxy resin can be measured by GPC, for example.

  Although it does not specifically limit to the said resin composition, It is preferable to use a phenol resin. Examples of the phenol resin include novolak-type phenol resins, resol-type phenol resins, and arylalkylene-type phenol resins. Among these, arylalkylene type phenol resins are preferable. Thereby, moisture absorption solder heat resistance can be improved further.

  Examples of the aryl alkylene type phenol resin include a xylylene type phenol resin and a biphenyl dimethylene type phenol resin. The biphenyl dimethylene type phenol resin can be represented by, for example, the formula (III).

Although the repeating unit n of the biphenyl dimethylene type phenol resin represented by the formula (III) is not particularly limited, 1 to 12 is preferable, and 2 to 8 is particularly preferable. If the repeating unit n is less than the lower limit, the heat resistance may be lowered. Moreover, since the compatibility with other resin will fall and workability | operativity may worsen when the said upper limit is exceeded, it is unpreferable.

  By combining the above-described cyanate resin (particularly novolac-type cyanate resin) and arylalkylene-type phenol resin, the crosslink density can be controlled and the adhesion between the metal and the resin can be improved.

Although content of the said phenol resin is not specifically limited, 1 to 55 weight% of the whole resin composition is preferable, and 5 to 40 weight% is especially preferable. If the content is less than the lower limit, the heat resistance may be reduced, and if the content exceeds the upper limit, the characteristics of low thermal expansion may be impaired.

The weight average molecular weight of the phenol resin is not particularly limited, but a weight average molecular weight of 400 to 18,000 is preferable, and 500 to 15,000 is particularly preferable. When the weight average molecular weight is less than the lower limit, tackiness may occur in the prepreg, and when the upper limit is exceeded, impregnation into the base material may be reduced during prepreg production, and a uniform product may not be obtained. is there.
The weight average molecular weight of the phenol resin can be measured by, for example, GPC.

Although it does not specifically limit to the said resin composition, It is preferable to use a coupling agent. The coupling agent improves the wettability of the interface between the cyanate resin and the inorganic filler, thereby fixing the cyanate resin and the like and the inorganic filler uniformly on the base material. Later solder heat resistance can be improved.
Any coupling agent can be used as long as it is usually used. Specifically, the coupling agent is selected from epoxy silane coupling agents, titanate coupling agents, aminosilane coupling agents, and silicone oil type coupling agents. It is preferred to use more than one type of coupling agent. Thereby, the wettability with the interface of an inorganic filler can be made high, and thereby heat resistance can be improved more.

  Although content of the said coupling agent is not specifically limited, 0.05-3 weight part is preferable with respect to 100 weight part of inorganic fillers, and 0.1-2 weight part is especially preferable. If the content is less than the lower limit, the inorganic filler cannot be sufficiently coated, and thus the effect of improving the heat resistance may be reduced. If the content exceeds the upper limit, the reaction is affected, and the bending strength is reduced. There is a case.

A curing accelerator may be used in the resin composition as necessary. A well-known thing can be used as said hardening accelerator. For example, organic metal salts such as zinc naphthenate, cobalt naphthenate, tin octylate, cobalt octylate, bisacetylacetonate cobalt (II), trisacetylacetonate cobalt (III), triethylamine, tributylamine, diazabicyclo [2,2 , 2] tertiary amines such as octane, 2-phenyl-4-methylimidazole, 2-ethyl-4-ethylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxyimidazole Imidazoles such as 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, and the like, or a mixture thereof. .

  Although content of the said hardening accelerator is not specifically limited, 0.05-5 weight% of the whole said resin composition is preferable, and 0.2-2 weight% is especially preferable. When the content is less than the lower limit, the effect of promoting curing may not appear, and when the content exceeds the upper limit, the storability of the prepreg may deteriorate.

In the resin composition, in addition to the cyanate resin, epoxy resin and phenol resin, other thermosetting resins such as vinyl ester resin and melamine resin, phenoxy resin, polyimide resin, polyamideimide resin, polyphenylene oxide resin, polyphenylene oxide resin, You may use together with thermoplastic resins, such as ether sulfone resin.
Moreover, additives other than the said components, such as a pigment and antioxidant, can be added to the said resin composition as needed.

  A fiber base material is impregnated with such a resin composition to obtain a prepreg. As the fiber base material, for example, a glass fiber base material such as a glass woven fabric or a glass nonwoven fabric, or an inorganic compound other than glass is used as a component. Examples thereof include inorganic fiber base materials such as woven fabric and non-woven fabric, organic fiber base materials composed of organic fibers such as aromatic polyamide resin, polyamide resin, aromatic polyester resin, polyester resin, polyimide resin, and fluororesin. Among these fiber base materials, glass fiber base materials represented by glass woven fabric are preferable in terms of strength and water absorption.

  Examples of the glass constituting the glass fiber substrate include E glass, C glass, A glass, S glass, D glass, NE glass, T glass, and H glass. Among these, T glass is preferable. Thereby, the thermal expansion coefficient of a glass fiber base material can be made small, and, thereby, the thermal expansion coefficient of a prepreg can be made small.

  Although the thickness of the said fiber base material (especially glass fiber base material) is not specifically limited, 10-300 micrometers is preferable and especially 15-100 micrometers is preferable. When the thickness is within the above range, the anisotropy in the surface direction of the prepreg (difference in thermal expansion in the surface direction) can be reduced even in a relatively thin prepreg.

  The fiber substrate is roughly classified into a woven fabric and a non-woven fabric. Among these, a woven fabric is preferable, and particularly, a fabric composed of a woven fabric in which warp and weft are plain woven (especially a glass fiber substrate). ) Is preferred. Thereby, when setting the X and Y directions orthogonal to each other on the surface of the fiber base material, the thermal expansion coefficient in each X and Y direction can be reduced, and the X and Y of the prepreg obtained thereby The coefficient of thermal expansion in the direction can be reduced.

  The glass fiber base material is preferably plain woven. In this case, the weft density of the warp yarn and the weft density of the glass fiber base material are preferably substantially the same. Specifically, the difference between the weft density of the warp and the weave density of the weft is preferably 20 / inch or less, and more preferably 15 / inch or less. Thereby, the difference between the thermal expansion coefficients in the X and Y directions can be particularly reduced.

Thermal expansion coefficient at 30 to 150 ° C. of the fiber base material is not particularly limited, but is preferably 10 ppm / ° C. or less, particularly preferably 0.1~5ppm / ℃. When the thermal expansion coefficient is within the above range, in particular, the thermal expansion coefficient of the prepreg can be reduced, thereby reducing the difference in thermal expansion coefficient with the semiconductor element when the circuit board is formed. When the difference in thermal expansion coefficient between the circuit board and the semiconductor element is reduced, the stress or the like generated at the connection portion can be reduced, thereby improving the connection reliability.

  Examples of the method of impregnating the fiber base material with the resin composition include, for example, a method of immersing the fiber base material in a resin varnish obtained by dissolving the resin composition in a solvent, a method of applying with various coaters, and the resin varnish. The method of spraying with spray is mentioned. Among these, the method of immersing the fiber base material in a resin varnish is preferable. Thereby, the impregnation property of the resin composition with respect to the fiber base material can be improved. In addition, when the said fiber base material is immersed in a resin varnish, a normal impregnation coating equipment can be used.

  The solvent used in the resin varnish desirably has good solubility in the resin composition, but a poor solvent may be used as long as it does not adversely affect the resin varnish. Examples of the solvent exhibiting good solubility include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, dimethylformamide, dimethylacetamide, N-methylpyrrolidone and the like.

The solid content of the resin varnish is not particularly limited, but the solid content of the resin composition is preferably 30 to 80% by weight, and particularly preferably 40 to 70% by weight. Thereby, the impregnation property to the fiber base material of the resin varnish can be improved.
A prepreg can be obtained by impregnating the fiber base material with the resin composition and drying at 80 to 200 ° C., for example.

The thickness of the prepreg thus obtained can be set to a predetermined thickness by adjusting the fiber base to be used, the amount of resin adhered to the fiber base, drying conditions, and the like.
The required prepreg thickness is determined by how much the insulating layer thickness of the circuit board is set.
The thickness of the prepreg is not particularly limited, but is preferably 0.01 to 1 mm, particularly 0.02 to 0.2 mm, and more preferably 0.02 to 0.1 mm. When the thickness is within the above range, the anisotropy in the surface direction of the prepreg can be reduced even in a relatively thin prepreg.

The prepreg thus obtained preferably has a small thermal expansion coefficient anisotropy in the surface direction (FIG. 1). The X and Y directions orthogonal to each other on the surface of the prepreg can be arbitrarily set. Here, a case where the warp direction of the plain weave fiber base material is set to the X direction and the weft direction is set to the Y direction will be described.
The cured product obtained by curing the prepreg has a thermal expansion coefficient [Ax] in the X direction of 10 ppm / ° C. or less at 30 to 150 ° C. and a thermal expansion coefficient [Ay] in the Y direction of 10 ppm / ° C. It is characterized by the following. Thereby, the isotropy of the thermal expansion coefficient in the surface direction of the circuit board using the prepreg can be improved, thereby increasing the degree of freedom of the circuit wiring pattern.
In the conventional circuit board, there is anisotropy (difference in thermal expansion in the plane direction) in the plane direction (two-dimensional direction) of the prepreg constituting the circuit board, and therefore, it is necessary to design the circuit wiring pattern in consideration thereof. there were. For example, when a wiring of a fine circuit having a wiring pitch of 20 μm or less is formed along the direction in which the thermal expansion is large, the circuit may be shifted. Therefore, it is necessary to increase the line width or increase the pitch between wirings.
On the other hand, when the prepreg of the present invention is used, the anisotropy in the plane direction can be reduced. Therefore, no matter how the circuit wiring is designed, the difference in coefficient of thermal expansion is small, so that wiring can be performed freely without considering the circuit shift or the like as in the prior art. Further, it is not necessary to change the pitch between the wirings in consideration of the directionality of the circuit board.
That is, the direction of the circuit wiring can be freely designed as shown in FIGS.

The thermal expansion coefficient [Ax] in the X direction at 30 to 150 ° C. of the cured product obtained by curing the prepreg is more preferably 8 ppm / ° C. or less, particularly 3 to 6 ppm / ° C. Preferably there is.
The thermal expansion coefficient [Ay] in the Y direction at 30 to 150 ° C. of the cured product obtained by curing the prepreg is more preferably 8 ppm / ° C. or less, particularly 3 to 6 ppm / It is preferable that it is ° C.
Furthermore, the thermal expansion coefficient [Ax] in the X direction at 30 to 150 ° C. of the cured product obtained by curing the prepreg is more preferably 8 ppm / ° C. or less, particularly 3 to 3 ° C. preferably 6 ppm / a ° C., and the Y-direction of the thermal expansion coefficient [Ay] is preferably more particularly at most 8 ppm / ° C., it is preferred that particularly 3~6ppm / ℃. Thereby, the difference in thermal expansion between the semiconductor element and the substrate made of the prepreg can be reduced, thereby further improving the connection reliability.

The reason why the connection reliability between the semiconductor element and the substrate can be improved when the thermal expansion coefficient in the X and Y directions of the cured product of the prepreg is set as described above is considered as follows.
The thermal expansion coefficient (both in the X and Y directions) of the semiconductor element is approximately 3.5 ppm / ° C. Therefore, when the difference between the thermal expansion coefficient in the X and Y directions of the circuit board (semiconductor element mounting board) on which the semiconductor element is mounted and the thermal expansion coefficient of the semiconductor element is reduced, the gap between the semiconductor element and the circuit board is reduced. Stress and warpage caused by differences in thermal expansion coefficients are reduced. When the stress or the like is reduced, the thermal shock resistance is improved, and as a result, the connection reliability is improved.

The absolute value of the difference between the thermal expansion coefficient [Ax] in the X direction and the thermal expansion coefficient [Ay] in the Y direction is not particularly limited, but is preferably 5 ppm / ° C. or less, particularly 1 to It is preferably 4 ppm / ° C. When the difference is within the above range, in addition to excellent connection reliability, the degree of freedom in circuit design is particularly improved.

  The thermal expansion coefficient can be measured by a method described in JIS K-7197 using a thermomechanical analysis (TMA) apparatus. Specifically, a measurement sample is set on a stage, a constant load is applied, the temperature is raised at a constant speed, the amount of expansion that occurs is detected as an electrical output by a differential transformer, and the relationship with temperature is examined.

Further possible, the thermal expansion coefficient in a plane direction at 30 to 150 ° C. of a cured product obtained by curing the prepreg is not particularly limited, but is preferably 10 ppm / ° C. or less, in particular 2~5ppm / ℃ Is preferred. When the thermal expansion coefficient is within the above range, the connection reliability between the semiconductor element and the circuit board can be improved.
Here, the surface direction means a longitudinal direction indicating the flow direction of the prepreg (machine direction of the prepreg) and a lateral direction indicating the width direction of the prepreg (anti-machine direction of the prepreg).

The cured product of the prepreg means a state in which the reaction of the functional group of the resin constituting the prepreg is completed, and can be evaluated by measuring the calorific value by DSC, for example. Specifically, it means a state in which the calorific value measured by DSC is hardly detected.
The conditions for obtaining such a cured product of prepreg are not particularly limited, but are preferably heat-treated at 120 to 220 ° C. for 30 to 180 minutes, more preferably 150 to 200 ° C. for 45 to 120 minutes.

The cured product obtained by curing the prepreg as described above has a thermal expansion coefficient [Ax] in the X direction of 30 to 150 ° C. of 10 ppm / ° C. or less and a thermal expansion coefficient [Ay] in the Y direction. By setting it to 10 ppm / ° C. or less, a circuit board having excellent performance can be obtained. Examples of a method for obtaining such a prepreg include a change in the ratio between the cyanate resin and the inorganic filler as described above, and selection of a fiber base material having a small thermal expansion coefficient.

  As described above, the prepreg has been described with reference to an example of a plain weave fiber base material woven with warp and weft. Good. Even in the case of these fiber base materials, it is preferable that the thermal expansion coefficients in the X and Y directions arbitrarily set are within the above ranges.

Next, a circuit board using the above prepreg (FIG. 1) will be described.
FIG. 2 is a side view schematically showing the circuit board before heating and pressurization.
As shown in FIG. 2, a plurality of the above-described prepregs 1 (1a, 1b, 1c, 1d) and a metal layer 2 are laminated on one side of the prepreg 1, and then heated and pressed to form a circuit board as shown in FIG. Get 10. As a result, it is possible to obtain the circuit board 10 having a wide degree of freedom in circuit wiring patterns.

Although the temperature to heat is not specifically limited, 120-220 degreeC is preferable and especially 150-200 degreeC is preferable.
Although the pressure to pressurize is not particularly limited, it is preferably 1.5 to 5 MPa, and particularly preferably 2 to 4 MPa.
Moreover, you may perform post-curing at the temperature of 150-300 degreeC with a high-temperature soot as needed.

  Examples of the metal constituting the metal layer 2 include copper or a copper-based alloy, aluminum or an aluminum-based alloy, and iron or an iron-based alloy.

  And the circuit wiring 21 as shown in FIGS. 4-6 is formed by performing the etching process etc. to the metal layer 2 of the circuit board 10 of FIG.

In the circuit board of FIG. 3, the case where a plurality of prepregs 1 are used has been described. However, the circuit board may be manufactured using a single prepreg.
Further, in the circuit board of FIG. 3, the metal layer 2 is provided only on one side of the prepreg 1, but it may be provided on both sides.

  Although the thickness of such a circuit board 10 is not specifically limited, 0.01-1 mm is preferable, 0.02-0.2 mm is especially preferable, 0.02-0.1 mm is further preferable. When the thickness is within the above range, the anisotropy in the surface direction of the circuit board 10 can be reduced even in the relatively thin circuit board 10.

Next, a semiconductor device will be described.
As shown in FIG. 7, the semiconductor device 100 is obtained by mounting the semiconductor element 4 via the solder balls 41 on the circuit wiring 21 provided on the circuit board 10 described above.
In the conventional circuit board, the connection reliability may be insufficient due to the anisotropy of the thermal expansion coefficient in the surface direction. Therefore, an insulating resin called underfill is filled between the semiconductor element and the circuit board to seal and reinforce the connection portion.
On the other hand, when the circuit board 10 of the present invention is used, the anisotropy of the thermal expansion coefficient in the plane direction is small, and the value is also small, so an underfill is filled between the semiconductor element and the circuit board. It is possible to improve connection reliability without doing so. Moreover, even if an underfill is used, it is only necessary to select a material condition by giving priority to the sealing function (that is, it is not necessary to provide a reinforcing effect). The range can be expanded when selecting in consideration.
In FIG. 4, the embodiment in which the semiconductor element 4 and the circuit wiring 21 are connected using the solder ball 41 has been described. However, the semiconductor device of the present invention is not limited to this. A circuit board may be connected.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited to this. First, a printed wiring board (circuit board) will be described.
( Reference Example 1)
(1) Preparation of resin varnish 15% by weight (hereinafter abbreviated as%) of novolak-type cyanate resin (Lonza Japan, Primaset PT-60, weight average molecular weight of about 2,600) as cyanate resin, and biphenyldi as epoxy resin 8% methylene type epoxy resin (Nippon Kayaku Co., Ltd., NC-3000P, epoxy equivalent 275), 7% biphenyldimethylene type phenol resin (Maywa Kasei Co., Ltd., MEH-7785-S, hydroxyl equivalent 203) as a phenol resin, and As a coupling agent, 0.3 part by weight (hereinafter abbreviated as “part”) is dissolved in methyl ethyl ketone at room temperature with respect to 100 parts by weight of an inorganic filler described later as an epoxy silane type coupling agent (Nihon Unicar Co., Ltd., A-187) Spherical fused silica SFP-10X (manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size) 0.3 [mu] m) 20% and spherical fused silica SO-32R (Admatechs Co., was added an average particle size 1.5 [mu] m) 50%, a resin varnish was prepared by stirring 10 minutes using a high speed stirrer.

(2) Manufacture of prepreg The above-mentioned resin varnish is made of glass woven fabric (base material of plain weave made of E glass, thickness 100 μm, weft density of warp 60 / inch, weft density of 58 / inch, Nitto Made by Spinning Co., Ltd., WEA-116E, thermal expansion coefficient from room temperature to 250 ° C. at 6 ppm / ° C.), dried in a heating furnace at 120 ° C. for 2 minutes and solidified varnish (ratio of resin and silica in the prepreg) About 50% of the prepreg was obtained.
The thermal expansion coefficient [Ax] in the X direction (longitudinal direction of the glass woven fabric) at 30 to 150 ° C. on the surface of the cured product obtained by treating this prepreg at 200 ° C. for 30 minutes is 6 ppm. The coefficient of thermal expansion [Ay] in the Y direction (lateral direction of the glass woven fabric) was 8 ppm / ° C. Here, the thermal expansion coefficient was performed as follows. Cut out 4 mm x 20 mm test pieces in the vertical and horizontal directions from the cured prepreg, and use a thermomechanical analyzer (TAMA2940, manufactured by TA Instruments) to obtain a thermal expansion coefficient of 5 in the X (vertical) and Y (transverse) directions. Measured at ° C / min.

(3) Manufacture of printed wiring board (circuit board) One sheet of the above-mentioned prepreg, 18 μm copper foil on both sides, and pressure-molded at a pressure of 4 MPa and a temperature of 200 ° C. for 2 hours for 0.1 mm on both sides A copper-clad printed wiring board was obtained. Printed wiring boards having other thicknesses were obtained by laminating prepregs accordingly.

( Reference Example 2)
Glass woven fabric was made of WEA-05E (plain weave base material made of E glass, thickness 53 μm, weft density 60 / inch, weft density 47 / inch, manufactured by Nitto Boseki Co., Ltd., from room temperature to 250 The same procedure as in Reference Example 1 was performed except that the coefficient of thermal expansion at 6 ° C. was changed to 6 ppm / ° C.
The thermal expansion coefficient [Ax] in the X direction (longitudinal direction of the glass woven fabric) at 30 to 150 ° C. on the surface of the cured product obtained by treating the prepreg with 230 ° C. for 30 minutes is 6 ppm. / ℃
And the coefficient of thermal expansion [Ay] in the Y direction (lateral direction of the glass woven fabric) was 7 ppm / ° C.

(Example 3)
A glass woven fabric is WTX-116E (a plain weave base made of T glass, thickness 100 μm, weft density of 60 yarns / inch, weft yarn density of 58 yarns / inch, manufactured by Nitto Boseki Co., Ltd., from room temperature to 250 The same procedure as in Reference Example 1 was conducted except that the resin varnish was mixed as follows instead of the coefficient of thermal expansion at 3 ° C./° C.).
Novolac type cyanate resin (Primerset PT-60) 20%, biphenyl dimethylene type epoxy resin (NC-3000P) 11%, biphenyl dimethylene type phenol resin (MEH-7851-S) 9% and epoxy silane type coupling agent (A-187) 0.3 part is dissolved in methyl ethyl ketone at room temperature, 10% spherical fused silica SFP-10X (manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 0.3 μm) and spherical fused silica SO-32R (Admatechs) Manufactured, average particle size 1.5 μm) was added.
The thermal expansion coefficient [Ax] in the X direction (longitudinal direction of the glass woven fabric) at 30 to 150 ° C. on the surface of the cured product obtained by treating the prepreg with 230 ° C. for 30 minutes is 5 ppm. The coefficient of thermal expansion [Ay] in the Y direction (lateral direction of the glass woven fabric) was 6 ppm / ° C.

Example 4
WTX-05E (a plain weave base material made of T glass, thickness 53 μm, warp weaving density 60 / inch, weft weaving density 47 / inch, manufactured by Nitto Boseki Co., Ltd., from room temperature to 250 Example 3 was performed except that the coefficient of thermal expansion at 3 ° C. was changed to 3 ppm / ° C.
The thermal expansion coefficient [Ax] in the X direction at 30 to 150 ° C. on the surface of the cured product obtained by treating this prepreg at 200 ° C. for 30 minutes is 5 ppm / ° C. , and Y The coefficient of thermal expansion [Ay] in the direction was 7 ppm / ° C.

( Reference Example 5)
The same procedure as in Reference Example 1 was conducted except that the resin varnish was mixed as follows.
Novolac-type cyanate resin (Primerset PT-60) 5%, biphenyldimethylene-type epoxy resin (NC-3000P) 20%, biphenyldimethylene-type phenolic resin (MEH-7851-S) 15%, and epoxysilane-type coupling 0.3 parts of the agent (A-187) was dissolved in methyl ethyl ketone at room temperature, and 10% spherical fused silica (SFP-10X) and 50% spherical fused silica (SO-32R) were added.
The thermal expansion coefficient [Ax] in the X direction at 30 to 150 ° C. on the surface of the cured product obtained by treating this prepreg at 200 ° C. for 30 minutes is 9 ppm / ° C. , and Y The thermal expansion coefficient [Ay] in the direction was 10 ppm / ° C.

( Reference Example 6)
The same procedure as in Reference Example 1 was conducted except that the glass woven fabric was WTX116E (thickness 100 μm, manufactured by Nitto Boseki Co., Ltd.) and bisphenol A type cyanate resin ( AroCy B-30, manufactured by Sumitomo Chemical Co., Ltd.) was used as the cyanate resin.
The thermal expansion coefficient [Ax] in the X direction at 30 to 150 ° C. on the surface of the cured product obtained by treating the prepreg with 200 ° C. for 30 minutes is 7 ppm / ° C. , and Y The thermal expansion coefficient [Ay] in the direction was 9 ppm / ° C.

( Reference Example 7)
The same procedure as in Example 3 was performed except that the biphenyldimethylene type epoxy resin was changed as follows. In place of the biphenyl dimethylene type epoxy resin, a novolak type epoxy resin (Dainippon Ink Chemical Industries, Epicron N-775, epoxy equivalent 190) was used.
The thermal expansion coefficient [Ax] in the X direction at 30 to 150 ° C. on the surface of the cured product obtained by treating this prepreg at 200 ° C. for 30 minutes is 8 ppm / ° C. , and Y The thermal expansion coefficient [Ay] in the direction was 9 ppm / ° C.

( Reference Example 8)
The same procedure as in Example 4 was conducted except that the biphenyldimethylene type phenol resin and the glass woven fabric were changed as follows. Instead of biphenyldimethylene type phenolic resin, novolak resin (manufactured by Sumitomo Bakelite, PR-51714, hydroxyl equivalent 103) is used, and glass woven fabric (WEA-116E) is used instead of glass woven fabric (WTX-05E). Using.
The thermal expansion coefficient [Ax] in the X direction at 30 to 150 ° C. on the surface of the cured product obtained by treating this prepreg at 200 ° C. for 30 minutes is 8 ppm / ° C. , and Y The thermal expansion coefficient [Ay] in the direction was 9 ppm / ° C.

Example 9
Example 3 was repeated except that the spherical fused silica was changed as follows. Instead of the spherical fused silica SFP-10X and SO-32R, FB-5SDX (manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 5 μm) was used.
The thermal expansion coefficient [Ax] in the X direction at 30 to 150 ° C. on the surface of the cured product obtained by treating the prepreg with 200 ° C. for 30 minutes is 7 ppm / ° C. , and Y The thermal expansion coefficient [Ay] in the direction was 8 ppm / ° C.

(Comparative Example 1)
The same procedure as in Reference Example 1 was conducted except that the resin varnish was mixed as follows.
Biphenyl dimethylene type epoxy resin (NC-3000P) 23%, biphenyl dimethylene type phenol resin (MEH-7851-S) 17%, curing aid 2-methylimidazole (manufactured by Shikoku Chemicals Co., Ltd., 2MZ) 0.4 part In addition, 0.3 part of an epoxy silane type coupling agent (A-187) was dissolved in methyl ethyl ketone at room temperature, and 10% spherical fused silica (SFP-10X) and 50% spherical fused silica (SO-32R) were added.
The thermal expansion coefficient [Ax] in the X direction at 30 to 150 ° C. on the surface of the cured product obtained by treating this prepreg with 200 ° C. for 30 minutes is 14 ppm / ° C. , and Y The thermal expansion coefficient [Ay] in the direction was 16 ppm / ° C.

(Comparative Example 2)
The same procedure as in Example 3 was followed, except that the resin varnish was blended as follows.
Novolac-type cyanate resin (Primerset PT-60) 20%, biphenyldimethylene-type epoxy resin (NC-3000P) 28%, biphenyldimethylene-type phenolic resin (MEH-7851-S) 22%, spherical fused silica (SFP-) 10%) and 10% spherical fused silica (SO-32R) were added.
The thermal expansion coefficient [Ax] in the X direction at 30 to 150 ° C. on the surface of the cured product obtained by treating this prepreg at 200 ° C. for 30 minutes is 16 ppm / ° C. , and Y The thermal expansion coefficient [Ay] in the direction was 18 ppm / ° C.

The following evaluation was performed about the printed wiring board obtained by the Example and the comparative example. The evaluation items are shown together with the evaluation method. The obtained results are shown in Table 1.
1. Warpage amount Printed wiring with a thickness of 0.4 mm was prepared, and 44 TEG chips (side 10 mm, thickness 0.55 mm) were inserted through 44 bumps (0.1 mm diameter, SnAg) at intervals of 0.2 mm. The chip was mounted and the amount of warpage of the chip was measured.

2. Glass transition temperature A printed wiring board having a thickness of 0.6 mm is etched on the entire surface, a test piece of 10 mm × 60 mm is cut out from the obtained laminate, and 3 ° C. using a dynamic viscoelasticity measuring apparatus DMA983 manufactured by TA Instruments. The temperature was increased at a rate of / min, and the peak position of tan δ was defined as the glass transition temperature.

3. Flame retardance According to the UL-94 standard, a 1.0 mm thick test piece was measured by the vertical method.

4). Water absorption: A double-sided printed wiring board having a thickness of 0.6 mm was entirely etched, and a 50 mm × 50 mm test piece was cut out from the obtained laminate and measured according to JIS C6481.

5. Moisture-absorbing solder heat resistance Cut out to 50mm x 50mm from double-sided printed wiring board with a thickness of 0.6mm.
A test piece was prepared by half-etching according to 6481. After processing with a 125 ° C. pressure cooker, the copper foil surface was floated in a 260 ° C. solder bath, and the processing time during which swelling occurred after 180 seconds was measured.

6). Design of circuit wiring The degree of freedom in designing circuit wiring was evaluated by measuring pattern deviation after heat treatment by etching a copper foil to form a test pattern. Each code is as follows.
(Double-circle): The shift | offset | difference of wiring is 1/3 or less of wiring width.
○: The displacement of the wiring exceeds 1/3 of the wiring width and is 1/2 or less.
(Triangle | delta): The shift | offset | difference of wiring exceeds 1/2 of wiring width, and is 2/3 or less.
X: The displacement of the wiring exceeds 2/3 of the wiring width.

As apparent from Table 1, Examples 3 to 4 and Example 9 had a small amount of warpage and a high degree of freedom in designing circuit wiring.
In addition, Examples 3 to 4 and Example 9 had a high glass transition temperature and high flame retardancy.
Further, Examples 3 to 4 and Example 9 had a low water absorption rate and were excellent in moisture absorption solder heat resistance.

Next, examples and comparative examples of the semiconductor device will be described.
A eutectic solder paste of 36% by weight of Pb-64% by weight of Sn was printed on the circuit boards obtained in Examples 3 to 4, Example 9 and Comparative Examples 1 and 2 by a printing method. The connecting portions were arranged in a matrix with a diameter of 0.08 mm and a pitch of 0.16 mm.
Then, TEG chips (side 10mm, thickness 0.55mm) are aligned and placed through eutectic solder balls of 44, 0.16mm spacing, φ0.08mm on one side, and reflow processing is performed. A semiconductor device was manufactured.
When the connection reliability of the obtained semiconductor device was evaluated, excellent connection reliability was confirmed for the semiconductor devices obtained in Examples 3 to 4 and Example 9.

The prepreg of the present invention can be suitably used for a circuit board, and in particular, can be suitably used for a semiconductor element mounting circuit board on which a semiconductor element is mounted.
The semiconductor device of the present invention can be suitably used for applications that require high connection reliability.

It is a perspective view which shows an example of a prepreg typically. It is a perspective view which shows an example of the process which manufactures a circuit board. It is a perspective view which shows an example of a circuit board. It is a perspective view which shows an example of the circuit board in which the circuit wiring was formed. It is a perspective view which shows an example of the circuit board in which the circuit wiring was formed. It is a perspective view which shows an example of the circuit board in which the circuit wiring was formed. It is a side view which shows an example of a semiconductor device.

DESCRIPTION OF SYMBOLS 1 Prepreg 1a Prepreg 1b Prepreg 1c Prepreg 1d Prepreg 2 Metal layer 21 Circuit wiring 4 Semiconductor element 41 Solder ball 10 Circuit board 100 Semiconductor device

Claims (6)

A prepreg obtained by impregnating a fiber base material with a resin composition containing a cyanate resin and an inorganic filler,
The content of the cyanate resin is a 5-5 0% by weight of the total resin composition,
The content of the inorganic filler is 50 to 80% by weight of the entire resin composition,
The main fibers constituting the fiber base material are glass fibers,
The glass constituting the glass fiber is T glass or S glass,
When the X and Y directions orthogonal to each other are set on the surface of the prepreg, the thermal expansion coefficient [Ax] in the X direction at 30 to 150 ° C. of the cured product obtained by curing the prepreg is 3 ppm / ° C. or more. A prepreg characterized by having a thermal expansion coefficient [Ay] in the Y direction of 3 ppm / ° C. or higher and 8 ppm / ° C. or lower.   The prepreg according to claim 1, wherein the fiber base material is a plain weave of warp and weft.   The prepreg according to claim 1 or 2, wherein the X direction is a warp direction of fibers constituting the fiber base material, and the Y direction is a weft direction of fibers constituting the fiber base material.   The prepreg according to any one of claims 1 to 3, wherein an absolute value of a difference between the thermal expansion coefficient [Ax] in the X direction and the thermal expansion coefficient [Ay] in the Y direction is 5 ppm / ° C or less.   The circuit board which has the hardened | cured material of the prepreg as described in any one of Claim 1 thru | or 4.   A semiconductor device, wherein a semiconductor element is mounted on the circuit board according to claim 5.