JP2016204560A - Method for producing low thermal expandable substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate having low thermal expansion properties and good adhesiveness to a copper foil.SOLUTION: There is provided a method for producing a low thermal expandable substrate which comprises: a step of producing a prepreg containing a resin composition layer composed of a thermosetting resin composition and a pair of glass cloth layers containing glass cloth and holding the resin composition layer; and a step of bringing a copper foil into contact with both principal surfaces of the prepreg to press in a reduced-pressure atmosphere. The thermosetting resin composition used for the production of the prepreg contains 70-92 mass% of a filler. In the filler, the ratio of particles having a particle diameter of 1 μm or less is 40 mass% or less. The glass cloth used for the production of the prepreg has a thickness of 80-150 μm and an air permeability of 5 cm/(cms)or less.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for manufacturing a low thermal expansion substrate.

  As a printed wiring board in electrical and electronic equipment, a copper clad laminate having copper foil bonded to both main surfaces is used. Such a copper clad laminated board is manufactured as follows, for example. First, a varnish is manufactured by diluting the thermosetting resin composition with a solvent or the like. Next, a prepreg is produced by impregnating the varnish into a fiber substrate made of a nonwoven fabric or the like. Further, a copper foil is superimposed on this prepreg and heated and pressurized. Thereby, the copper clad laminated board by which copper foil was bonded together on both main surfaces is manufactured.

  However, such a copper clad laminate has a high coefficient of thermal expansion because it contains a thermosetting resin composition. For this reason, when the silicon chip is flip-mounted, stress is generated due to the difference in thermal expansion coefficient from the silicon chip, and sufficient connection reliability cannot be obtained. For this reason, it has been studied to make a thermosetting resin composition contain a large amount of an inorganic filler, impregnate it into a fiber base material to produce a prepreg, and further produce a low thermal expansion substrate (for example, , See Patent Document 1).

JP 2011-111508 A

  However, as described above, when a large amount of inorganic filler is contained in the thermosetting resin composition, the resin component in the prepreg is less likely to penetrate into the roughened surface of the copper foil, and a sufficient anchor effect cannot be obtained. Therefore, the adhesiveness of copper foil falls.

  In order to improve the adhesiveness of the copper foil, for example, it has been studied to provide a resin layer for increasing the adhesion on the surface of the copper foil. However, from the viewpoint of cost and the like, generally, a copper foil provided with a resin layer is not used.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a substrate having low thermal expansibility and good copper foil adhesion.

The method for producing a low thermal expansion substrate of the present invention produces a prepreg having a resin composition layer made of a thermosetting resin composition and a pair of glass cloth layers including a glass cloth and sandwiching the resin composition layer. And a step of bringing the copper foil into contact with both main surfaces of the prepreg and pressurizing in a reduced pressure atmosphere. The thermosetting resin composition used for manufacturing the prepreg includes 70 to 92% by mass of a filler. In the filler, the proportion of particles having a particle size of 1 μm or less is 40% by mass or less. The glass cloth used for manufacturing the prepreg has a thickness of 80 to 150 μm and air permeability of 5 cm ³ / (cm ² · s) or less.

  According to the production method of the present invention, after producing a prepreg having a resin composition layer and a pair of glass cloth layers sandwiching the resin composition layer, the copper foil is brought into contact with both the main surfaces and pressurized in a reduced-pressure atmosphere. As a result, it is possible to produce a substrate having low thermal expansion and good copper foil adhesion.

In particular, a thermosetting resin composition used for the production of prepreg is one containing 70 to 92% by mass filler, and the proportion of particles having a particle size of 1 μm or less is 40% by mass or less as the filler. And having a low thermal expansion by using a glass cloth having a thickness of 80 to 150 μm and an air permeability of 5 cm ³ / (cm ² · s) or less as a glass cloth used for the production of a prepreg, And a board | substrate with favorable adhesiveness of copper foil can be manufactured.

The figure which shows the manufacturing method of the prepreg in embodiment. Sectional drawing which shows the prepreg in embodiment. Sectional drawing which shows the bonding method of the copper foil in embodiment. Sectional drawing which shows the low thermal expansion board | substrate in embodiment.

Hereinafter, an embodiment of a method for producing a low thermal expansion substrate will be described.
A method for producing a low thermal expansion substrate comprises a step of producing a prepreg having a resin composition layer comprising a thermosetting resin composition and a pair of glass cloth layers including a glass cloth and sandwiching the resin composition layer (hereinafter referred to as “a prepreg”). And a prepreg manufacturing step), and a step of bringing the copper foil into contact with both main surfaces of the prepreg and pressurizing in a reduced pressure atmosphere (hereinafter referred to as a molding step).

The thermosetting resin composition used for manufacturing the prepreg includes 70 to 92% by mass of a filler. The ratio of particles having a particle size of 1 μm or less in the filler is 40% by mass or less. The glass cloth used for manufacturing the prepreg has a thickness of 80 to 150 μm and air permeability of 5 cm ³ / (cm ² · s) or less.

  According to such a manufacturing method, it is possible to manufacture a substrate having low thermal expansibility and good copper foil adhesion. The reason why such a substrate can be manufactured is considered as follows.

  That is, the resin component oozes out from between the fillers in the resin composition layer by bringing a copper foil into contact with both main surfaces of the prepreg and pressing in a reduced pressure atmosphere. The oozing resin component passes through the pair of glass cloths and moves to the outside thereof. On the other hand, most of the filler cannot penetrate the glass cloth due to its size and the like. Thereby, it will be in the state in which only a resin component exists in the outer side of a pair of glass cloth. For this reason, it is thought that a resin component contacts the roughening surface of copper foil, and it is easy to permeate, and the adhesiveness of copper foil becomes favorable.

  Moreover, about the part between a pair of glass cloth, a filler is highly filled to the grade which fillers contact by decreasing a resin component. It is considered that low thermal expansion can be obtained by increasing the filling of such a filler.

  Hereinafter, embodiments of the present invention will be specifically described.

[Thermosetting resin composition]
First, the thermosetting resin composition used for manufacture of a prepreg is demonstrated.
The thermosetting resin composition preferably contains a thermosetting resin, a curing agent, a curing accelerator, and a filler. Hereinafter, each component will be described.

(Thermosetting resin)
Examples of the thermosetting resin include thermosetting resins such as epoxy resins, phenol resins, and cyanate resins that are generally used for the production of prepregs. Among these, an epoxy resin is preferable from the viewpoints of insulation, heat resistance, versatility, and high filling of the filler.

  As the epoxy resin, a glycidyl ether type epoxy resin having two or more epoxy groups per molecule is preferably used. These include: biphenyl type epoxy resin; dicyclopentadiene type epoxy resin; phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, bisphenol F novolac type epoxy resin, bisphenol S novolac type epoxy Examples thereof include novolac type epoxy resins such as resins; bisphenol type liquid epoxy resins such as bisphenol A type liquid epoxy resins and bisphenol F type liquid epoxy resins. These epoxy resins may be used alone or in combination of two or more. Among these, a biphenyl type epoxy resin is particularly preferable.

  The epoxy resin preferably contains a crystalline epoxy resin from the viewpoint of workability and the like. Moreover, it is preferable that an epoxy resin contains a solid epoxy resin at normal temperature from viewpoints of workability | operativity. The softening point of the epoxy resin that is solid at room temperature is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, and even more preferably 65 ° C. or higher. Moreover, the softening point of the epoxy resin that is solid at room temperature is preferably 120 ° C. or lower because the viscosity is lowered to such an extent that the filler is sufficiently dispersed by heating. In addition, the softening point in this specification is measured according to JIS K7121.

(Curing agent)
A hardening | curing agent can be suitably selected according to the kind of thermosetting resin. When the thermosetting resin is an epoxy resin, an amine curing agent, a phenol curing agent, a phosphorus curing agent, or the like can be used. Among these, a phenol-based curing agent is preferable from the viewpoints of reactivity, properties of the cured product, and filling property of the filler.

  As a phenol type hardening | curing agent, what has two or more phenolic hydroxyl groups in 1 molecule is used suitably. Examples thereof include novolak resins such as phenol novolak resins and cresol novolak resins; aralkyl type phenol resins such as phenol aralkyl resins and biphenyl aralkyl resins; polyfunctional aromatic phenol resins, and modified resins thereof. These phenol resins may be used alone or in combination of two or more. Among these, an aralkyl type phenol resin is preferable and a phenol aralkyl resin is more preferable from the viewpoints of reactivity, characteristics of a cured product, and filler filling properties.

  The phenolic curing agent preferably contains a phenolic curing agent that is solid at room temperature from the viewpoint of workability and the like. The softening point of the phenolic curing agent that is solid at room temperature is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, and even more preferably 65 ° C. or higher. In addition, the softening point of the phenolic curing agent that is solid at room temperature is preferably 120 ° C. or less because the viscosity is lowered to such an extent that the filler is sufficiently dispersed by heating.

  The content of the phenolic curing agent is such that the equivalent ratio of the epoxy group in the epoxy resin and the functional group in the phenolic curing agent is 1: 0.1 to 1.5 from the viewpoint of reactivity, physical properties of the cured product, and the like. Preferably, it is 0.5 to 1.3, more preferably 0.8 to 1.2.

  The total content of the thermosetting resin and the curing agent is preferably 6% by mass or more in the entire thermosetting resin composition from the viewpoint of achieving both low thermal expansion and reliability of the finally obtained substrate. 8 mass% or more is more preferable, and 10 mass% or more is further more preferable. For the same reason, the total content of the thermosetting resin and the curing agent is preferably 25% by mass or less, more preferably 20% by mass or less, and more preferably 16% by mass or less in the entire thermosetting resin composition. Is more preferable.

(Curing accelerator)
The thermosetting resin composition preferably contains a curing accelerator from the viewpoint of curing speed and the like. A hardening accelerator can be suitably selected according to the kind of thermosetting resin.

  When an epoxy resin is used as the thermosetting resin, a known curing accelerator such as an imidazole curing accelerator, an organic phosphorus curing accelerator, an amine curing accelerator, or a thiol curing accelerator can be used. Among these, an imidazole-type curing accelerator is preferable from the viewpoint of reactivity, physical properties of a cured product, and the like. Examples of the imidazole curing accelerator include imidazole, 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, and 2-heptadecylimidazole. These curing accelerators may be used alone or in combination of two or more.

  The content of the curing accelerator is preferably appropriately selected according to the type of the curing accelerator. When an epoxy resin is used as the thermosetting resin and a phenolic curing agent is used as the curing agent, from the viewpoints of reactivity, physical properties of the cured product, etc., the total amount of epoxy resin and phenolic curing agent is 100 parts by mass. 1 mass part or more is preferable, 0.5 mass part or more is more preferable, and 2.0 mass part or more is further more preferable. For the same reason, the content of the curing accelerator is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, and further preferably 2.0 parts by mass or less.

(Filler)
As the filler, known inorganic fillers such as silica, alumina, zirconia, and boron nitride can be used. Further, as the filler, those functioning as a flame retardant such as aluminum hydroxide and magnesium hydroxide can be used. These fillers may be used alone or in combination of two or more. Among these, silica is preferable from the viewpoints of versatility and filling properties.

  The shape of the filler may be spherical, scaly, or indefinite, but spherical is preferred from the viewpoint of filling properties.

  The average particle diameter of the filler is preferably 0.5 μm or more, more preferably 1 μm or more, and further preferably 3 μm or more from the viewpoint of suppressing permeation through the glass cloth. Further, from the viewpoint of filling properties, the average particle size of the filler is preferably 40 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. The average particle size means a particle size (d50) at which the integrated volume from 0 μm becomes 50% in the particle size distribution. The average particle diameter can be measured using a laser diffraction / scattering particle size distribution measuring apparatus.

  The ratio of particles having a particle size of 1 μm or less in the filler is 40% by mass or less. Particles having a particle size of 1 μm or less are likely to pass through the glass cloth, and thereby the adhesiveness of the copper foil is likely to be lowered. When the ratio of the particles having a particle size of 1 μm or less in the filler is 40% by mass or less, the amount of particles that pass through the glass cloth is reduced, thereby improving the adhesion of the copper foil. The proportion of particles having a particle size of 1 μm or less in the filler is preferably 35% by mass or less, and more preferably 30% by mass or less. In addition, although 0 mass% may be sufficient as the ratio of a particle | grain with a particle size of 1 micrometer or less, 5 mass% or more is preferable and 10 mass% or more is more preferable.

  Further, the proportion of particles having a particle size of 0.2 μm or less in the filler is preferably 30% by mass or less. Thereby, the adhesiveness of copper foil becomes further favorable. The proportion of particles having a particle size of 0.2 μm or less in the filler is preferably 25% by mass or less, and more preferably 20% by mass or less. The proportion of particles having a particle size of 0.2 μm or less may be 0% by mass, preferably 1% by mass or more, and more preferably 3% by mass or more. The proportion of particles having a particle size of 1 μm or less and the proportion of particles having a particle size of 0.2 μm or less in the filler can be measured using a laser diffraction / scattering particle size distribution measuring apparatus.

  The content of the filler (including particles having a particle size of 1 μm or less) is 70 to 70% in the entire thermosetting resin composition from the viewpoint of achieving both low thermal expansion and reliability of the finally obtained substrate. 92 mass% is preferable, 76-90 mass% is more preferable, 82-88 mass% is further more preferable.

(Silane coupling agent)
The thermosetting resin composition preferably contains a silane coupling agent from the viewpoint of improving the dispersibility of the filler. Silane coupling agents include aminosilane coupling agents such as γ-aminopropyltrimethoxysilane, epoxy silane coupling agents such as γ-glycidoxypropyltrimethoxysilane, and mercaptosilane couplings such as γ-mercaptopropyltrimethoxysilane. Agents. These silane coupling agents may be used alone or in combination of two or more. Among these, an epoxy silane coupling agent is preferable from the viewpoint of improving the dispersibility of the filler.

  From the viewpoint of improving the dispersibility of the filler, the content of the silane coupling agent is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, based on 100 parts by mass of the filler. 3 parts by mass or more is more preferable. Further, the content of the silane coupling agent is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and still more preferably 1 part by mass or less.

  In addition to the above-described components, the thermosetting resin composition can contain an antifoaming agent, a leveling agent, and other commonly used additives as required, as long as they do not contradict the spirit of the present invention.

  The total content of the thermosetting resin, curing agent, curing accelerator, and filler is preferably 80% by mass or more, more preferably 90% by mass or more, and 95% by mass in the entire thermosetting resin composition. The above is more preferable. The total content of these components may be 100% by mass in the thermosetting resin composition.

  The thermosetting resin composition preferably contains an epoxy resin as the thermosetting resin, a curing agent for the epoxy resin as the curing agent, and a curing accelerator for the epoxy resin as the curing accelerator. The total content of the epoxy resin, the epoxy resin curing agent, the epoxy resin curing accelerator, and the filler is preferably 80% by mass or more, and more preferably 90% by mass or more in the entire thermosetting resin composition. 95 mass% or more is more preferable. The total content of these components may be 100% by mass in the thermosetting resin composition.

(Method for producing thermosetting resin composition)
The thermosetting resin composition can be produced by mixing the above-described components. As the mixing device, a known mixer such as a roll or a mixer can be used. The mixing temperature is preferably equal to or higher than the softening point of the thermosetting resin or the curing agent. Usually, the temperature during mixing is preferably 50 ° C. or higher, and more preferably 80 ° C. or higher. Further, from the viewpoint of productivity and the like, the temperature during mixing is preferably 160 ° C. or less, and more preferably 140 ° C. or less.

[Prepreg manufacturing process]
Next, the prepreg manufacturing process will be described.
FIG. 1 is a diagram for explaining a method for producing a prepreg. FIG. 2 is a cross-sectional view of a prepreg manufactured by such a method.

  As FIG. 1 shows, the prepreg manufacturing apparatus 10 has a pair of metal rolls 11 and 12, for example. The pair of metal rolls 11 and 12 are configured so that, for example, the temperature can be adjusted and the distance between them can be adjusted. A pair of continuous glass cloths 13 and 14 are supplied between the pair of metal rolls 11 and 12. Moreover, between the pair of glass cloths 13 and 14, for example, a thermosetting resin composition 15 heated to a temperature equal to or higher than the softening point of the thermosetting resin is supplied. Usually, the pair of continuous glass cloths 13 and 14 and the thermosetting resin composition 15 are supplied to the pair of metal rolls 11 and 12 from the upper side in the vertical direction.

  In such a prepreg manufacturing apparatus 10, a prepreg is manufactured as follows. First, when the pair of metal rolls 11 and 12 are rotated, the pair of glass cloths 13 and 14 are drawn between the pair of metal rolls 11 and 12. Accordingly, the thermosetting resin composition 15 is drawn between the pair of glass cloths 13 and 14.

  Thereafter, the pair of glass cloths 13 and 14 and the thermosetting resin composition 15 pass between the pair of metal rolls 11 and 12, so that the pair of glass cloths 13 and 14 and the thermosetting resin composition 15 Are integrated to produce the prepreg 16.

  As shown in FIG. 2, the prepreg 16 includes a pair of glass cloth layers 17 and 18 and a resin composition layer 19 that is disposed between them and adheres them. The pair of glass cloth layers 17 and 18 includes a pair of glass cloths 13 and 14. The pair of glass cloths 13, 14 in the pair of glass cloth layers 17, 18 may be impregnated with the thermosetting resin composition 15, but is usually not impregnated with the thermosetting resin composition 15. It is preferable. The resin composition layer 19 is composed of the thermosetting resin composition 15, preferably in a semi-cured state, and more preferably in a solid state having no adhesiveness at 25 ° C.

  In the production of the prepreg 16, it is preferable to heat the thermosetting resin composition 15 above the softening point of the thermosetting resin or curing agent. Such heating facilitates the integration of the pair of glass cloths 13 and 14 and the thermosetting resin composition 15 and the adjustment of the thickness of the prepreg 16. Usually, the heating temperature is preferably 80 ° C. or higher. In addition, since the thermosetting resin composition 15 becomes easy to harden when temperature becomes high, 140 degreeC or less is preferable and heating temperature is 120 degrees C or less more preferable. The heating temperature can be adjusted by a pair of metal rolls 11 and 12, for example.

  In order to make the thickness of the prepreg 16 constant, it is preferable to keep the temperature of the thermosetting resin composition 15 constant within the above range. The temperature is maintained by a pair of metal rolls 11 and 12, for example.

It is preferable that the glass cloths 13 and 14 used for manufacturing the prepreg 16 have air permeability of 5 cm ³ / (cm ² · s) or less. Here, the air permeability is a scale representing the degree of air ventilation, and is measured according to the provisions of JIS R 3420: 2013 7.13. When the air permeability is 5 cm ³ / (cm ² · s) or less, the penetration of the filler is easily suppressed, and only the resin component is easily transmitted, so that the adhesiveness of the copper foil is improved. Breathable is ^{preferably 2cm 3 / (cm 2 · s} ) or ^less, and more preferably ^{1cm 3 / (cm 2 · s} ) or less. Usually, air permeability of 0.1 cm ³ / (cm ² · s) is sufficient.

  The glass cloths 13 and 14 are preferably plain weave glass cloths in which twisted yarns made by combining fine filaments are woven as warps and wefts. As the plain weave glass cloth, a plain weave glass cloth generally used for a copper clad laminate or the like can be used. As the glass cloths 13 and 14, those subjected to fiber opening treatment are particularly preferable. When the fiber opening process is performed, the gap between stitches called a basket hole is reduced, and the permeation of the filler is further suppressed.

  The average diameter (average filament diameter) of the filaments constituting the glass cloths 13 and 14 is preferably 13 μm or less, more preferably 10 μm or less, and even more preferably 8 μm or less, from the viewpoint of increasing the permeability of the resin component. Usually, the average filament diameter is preferably 5 μm or more. Here, the average filament diameter is obtained by measuring the filament diameter at an arbitrary position using an optical microscope for 50 arbitrary filaments constituting the glass cloths 13 and 14, and arithmetically averaging the measured filament diameters. It is obtained.

  The thickness of the glass cloths 13 and 14 used for the production of the prepreg 16 is preferably 80 μm or more, more preferably 85 μm or more, and further preferably 90 μm or more, from the viewpoint of suppressing the permeation of the filler. Moreover, from the viewpoint of increasing the permeability of the resin component, the thickness of the glass cloths 13 and 14 is preferably 150 μm or less, more preferably 110 μm or less, and even more preferably 105 μm or less.

  The material of the glass cloths 13 and 14 can be appropriately selected according to the application. For example, E glass is preferable from the viewpoint of cost reduction. Further, from the viewpoint of low thermal expansion, glass having a small thermal expansion coefficient such as S glass or T glass is preferable.

  The softening point of the resin composition layer 19 is preferably 40 ° C. or higher, more preferably 45 ° C. or higher, and further preferably 48 ° C. or higher from the viewpoint of workability and the like. In addition, the softening point of the resin composition layer 19 is preferably 120 ° C. or less from the viewpoint of increasing the filling of the filler.

  The melt viscosity at 100 ° C. of the resin composition layer 19 is preferably 200 Pa · s or less, more preferably 100 Pa · s or less, and even more preferably 50 Pa · s or less, from the viewpoint of increasing the filling of the filler. The melt viscosity at 100 ° C. of the resin composition layer 19 is usually 10 Pa · s or more. The melt viscosity can be measured using, for example, a rheometer (trade name: AEES-G02 manufactured by TA Instruments Japan Co., Ltd.).

  The thickness of the resin composition layer 19 is preferably 300 μm or more, and more preferably 400 μm or more, from the viewpoints of low thermal expansion and copper foil adhesion. Moreover, from a viewpoint of suppressing the thickness of the board | substrate finally obtained, 1200 micrometers or less are preferable, 1000 micrometers or less are more preferable, and 800 micrometers or less are further more preferable.

  The thickness of the prepreg 16 is preferably 350 μm or more, and more preferably 450 μm or more, from the viewpoint of low thermal expansion and copper foil adhesion. Moreover, from a viewpoint of suppressing the thickness of the board | substrate finally obtained, 1300 micrometers or less are preferable, 1100 micrometers or less are more preferable, and 900 micrometers or less are further more preferable.

[Molding process]
Next, the molding process will be described.
In the molding step, for example, as shown in FIG. 3, a pair of copper foils 21 and 22 are arranged in contact with both main surfaces of the prepreg 16. As the copper foils 21 and 22, general-purpose electrolytic copper foils or rolled copper foils generally used for copper-clad laminates and the like can be used. The thickness of the copper foils 21 and 22 is preferably 5 μm or more, and more preferably 10 μm or more, from the viewpoint of ensuring reliability with respect to pinholes and the like. Further, from the viewpoint of suppressing the thickness of the finally obtained substrate, the thickness of the copper foils 21 and 22 is preferably 40 μm or less, and more preferably 30 μm or less.

  On both surfaces of the pair of copper foils 21 and 22, for example, a pair of mirror plates made of stainless steel for pressurizing them is disposed (not shown). Thereafter, the whole is pressurized under a reduced pressure atmosphere to integrate the prepreg 16 and the pair of copper foils 21 and 22. The pressurization under a reduced-pressure atmosphere can be performed using, for example, a press that is generally used for forming a laminated plate and can pressurize under a reduced-pressure atmosphere.

  By pressurization in such a reduced-pressure atmosphere, the resin component oozes out from the resin composition layer 19, that is, the thermosetting resin composition 15, and the oozed resin component is outside the pair of glass cloth layers 17 and 18. To penetrate. The resin component that has passed through the glass cloth layers 17 and 18 contacts the roughened surfaces of the copper foils 21 and 22. On the other hand, most of the filler does not pass through the glass cloth layers 17 and 18 and remains between the pair of glass cloth layers 17 and 18. Thereafter, the resin component, that is, the resin component that has passed through the pair of glass cloth layers 17 and 18 and the resin component remaining between the pair of glass cloth layers 17 and 18 are cured. After curing, the pair of mirror plates used for pressurization are removed.

  With such a manufacturing method, the substrate 23 as shown in FIG. 4 can be manufactured. The substrate 23 has a high filling layer 24 in which a filler is highly filled between the pair of glass cloth layers 17 and 18. The high filling layer 24 is formed of a filler that remains without passing through the pair of glass cloth layers 17 and 18, and has a higher filler content than the resin composition layer 19.

  The substrate 23 has a resin layer 25 between the glass cloth layer 17 and the copper foil 21, and a resin layer 26 between the glass cloth layer 18 and the copper foil 22. The resin layers 25 and 26 are formed by curing the resin component that has passed through the glass cloth layers 17 and 18, and have a higher resin component content than the resin composition layer 19.

  For such a substrate 23, low thermal expansion can be obtained by the high filling layer 24 having a high filler content. Further, high thermal conductivity can be obtained by the high filling layer 24 having a high filler content. Further, the adhesiveness of the copper foils 21 and 22 is improved by the resin layers 25 and 26 having a high resin component content. Further, the glass cloth layers 17 and 18 have high strength.

  The degree of vacuum in the reduced-pressure atmosphere is preferably 50 kPa or less, more preferably 20 kPa or less, and even more preferably 10 kPa or less from the viewpoint of increasing the permeability of the resin component to the glass cloth layers 17 and 18. From the viewpoint of productivity and the like, the vacuum degree of the reduced pressure atmosphere is preferably 1 kPa or more, more preferably 3 kPa or more, and further preferably 5 kPa or more.

  From the viewpoint of increasing the permeability of the resin component to the glass cloth layers 17 and 18, the pressure of the pressurization is preferably 1 MPa or more, more preferably 2 MPa or more, and further preferably 3 MPa or more. From the viewpoint of productivity and the like, the pressure of pressurization is preferably 6 MPa or less, more preferably 5 MPa or less, and further preferably 4 MPa or less.

  The pressurization time in a reduced-pressure atmosphere is preferably 30 minutes or more, more preferably 50 minutes or more, and even more preferably 70 minutes or more from the viewpoint of increasing the permeability of the resin component to the glass cloth layers 17 and 18. From the viewpoint of productivity and the like, the pressurization time in a reduced pressure atmosphere is preferably 150 minutes or less, more preferably 130 minutes or less, and even more preferably 110 minutes or less.

  In pressurization under a reduced pressure atmosphere, it is preferable to heat the prepreg 16 and the pair of copper foils 21 and 22. The heating temperature is preferably equal to or higher than the softening point of the resin composition layer 19 from the viewpoint of increasing the permeability of the resin component to the glass cloth layers 17 and 18. Further, from the viewpoint of curing the resin component, a temperature higher than the curing temperature of the resin component is preferable. Usually, the heating temperature is preferably 150 ° C. or higher, more preferably 160 ° C. or higher, and further preferably 170 ° C. or higher. Further, from the viewpoint of productivity and the like, 210 ° C. or lower is preferable, 200 ° C. or lower is more preferable, and 190 ° C. or lower is further preferable.

Hereinafter, a detailed description will be given with reference to examples.
In addition, this invention is not limited at all by these Examples.

Example 1
<Preparation of thermosetting resin composition>
First, a thermosetting resin composition was prepared as follows. Biphenyl type epoxy resin (trade name: YX4000, epoxy equivalent: 193, solid at normal temperature, softening point: 105 ° C., crystallinity) 5 parts by mass as thermosetting resin, phenol aralkyl resin as curing agent (Mitsui Chemicals, trade name: XL325M, solid at ordinary temperature, softening point: 80 ° C.) 4 parts by mass, 2-heptadecylimidazole (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.15 parts by mass as a curing accelerator, filler As a spherical silica (manufactured by Tatsumori Co., Ltd., trade name: EUF-46V, average particle size: 5 μm, proportion of particles having a particle size of 1 μm or less: 25 mass%, proportion of particles having a particle diameter of 0.2 μm or less: 10 mass% ) 53 parts by mass and 0.4 part by mass of epoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM-402) were blended and further kneaded at 120 ° C. using a hot roll. Thereby, the thermosetting resin composition whose content of a filler is 84.7 mass% was prepared.

<Manufacture of prepreg>
Next, the opened glass cloth (manufactured by Nittobo, IPC spec: 2116 type, air permeability: 0.6 cm ³ / (cm ² · s), plain weave, thickness: 95 μm, average filament diameter: 7 μm) Prepared. As shown in FIG. 1, two glass cloths are conveyed by rotation of two metal rolls through two glass cloths between two metal rolls. At this time, the rotation speed of the metal roll was adjusted so that the conveyance speed of the glass cloth was 1 m / min.

  And the thermosetting resin composition heated at 80 degreeC and softened between the two glass cloths was supplied. Thus, two glass cloths and the thermosetting resin composition were integrated to produce a prepreg.

  The prepreg is composed of 85% by mass of a thermosetting resin composition and 15% by mass of glass cloth, a pair of glass cloth layers, and a resin composition layer composed of a thermosetting resin composition disposed therebetween. Have The thickness of the prepreg is 800 μm. The thickness of the resin composition layer is 550 μm. The resin composition layer is in a semi-cured state and is a solid having no adhesiveness at 25 ° C. The softening point of the resin composition layer is 50 ° C. The melt viscosity at 100 ° C. of the resin composition layer is 50 Pa · s.

<Molding by pressurization under reduced pressure atmosphere>
Copper foil (made by Mitsui Kinzoku Co., Ltd., trade name: 3EC-VLP, thickness: 18 μm) was placed on both sides of the prepreg. Thereafter, a pair of stainless steel plates and a pair of cushion materials were arranged in this order on both sides, and pressure was applied in a reduced pressure atmosphere. At this time, the degree of vacuum in the reduced-pressure atmosphere was 7.5 ka, the pressing pressure was 3.5 MPa, the heating temperature was 180 ° C., and the pressing time was 90 minutes. Thereafter, the pair of stainless steel plates and the pair of cushion materials were removed. Thereby, a substrate having a thickness of 0.7 mm was produced.

(Example 2)
A substrate having a thickness of 0.45 mm was produced in the same manner as in Example 1 except that the thickness of the prepreg was 500 μm and the thickness of the resin composition layer was 270 μm. In addition, the thickness of the prepreg and the resin composition layer was adjusted with the space | interval of the two metal rolls used for manufacture of a prepreg.

Example 3
As a filler, spherical silica (average particle size: 8.5 μm, proportion of particles having a particle size of 1 μm or less: 17% by mass, proportion of particles having a particle size of 0.2 μm or less: 7% by mass, UHR-500S (manufactured by Tatsumori Co., Ltd.) Substrate) was used in the same manner as in Example 1 except that the classified product) was used. The softening point of the resin composition layer is 52 ° C., and the melt viscosity of the resin composition layer at 100 ° C. is 150 Pa · s.

(Comparative Example 1)
Glass cloth not subjected to fiber opening treatment instead of glass cloth subjected to fiber opening treatment (manufactured by Nittobo, IPC spec: 2116 type, air permeability: 7.5 cm ³ / (cm ² · s), plain weave, thickness : 98 μm, average filament diameter: 7 μm) was used in the same manner as in Example 1 to produce a substrate.

(Comparative Example 2)
As a filler, spherical silica (average particle diameter: 0.8 μm, ratio of particles having a particle diameter of 1 μm or less: 46 mass%, ratio of particles having a particle diameter of 0.2 μm or less: 36 mass%, EUF-3 (manufactured by Tatsumori Co., Ltd.) Substrate) was used in the same manner as in Example 1 except that the classified product) was used. The softening point of the resin composition layer was 80 ° C., and the melt viscosity at 100 ° C. was 2600 Pa · s.

  For the substrates of Examples and Comparative Examples, the copper foil adhesion strength and the thermal expansion coefficient were measured as shown below.

(Copper foil adhesive strength)
A 10 mm wide slit was put in the substrate, the copper foil was peeled off at a speed of 50 mm / min in a direction perpendicular to the surface of the substrate, and the strength at that time was measured.

(Coefficient of thermal expansion)
Each thermal expansion coefficient in the surface direction (XY direction) and thickness direction (Z) of the substrate is measured by a TMA method using a thermomechanical analyzer (trade name: TMA / SS6000, manufactured by Seiko Instruments Inc.). The measurement was performed in the range of 25 to 280 ° C. under a temperature increase condition of a load of 5 mN and 10 ° C./min under an atmosphere.

As is clear from the results of Examples 1 to 3, the proportion of the filler contained in the thermosetting resin composition is 70 to 92 mass%, the proportion of particles having a particle size of 1 μm or less in the filler is 40 mass% or less, When the thickness of the glass cloth is 80 to 150 μm and the air permeability is 5 cm ³ / (cm ² · s) or less, it is possible to produce a substrate having low thermal expansion and good adhesion of the copper foil.

On the other hand, as is clear from the results of Comparative Example 1, when the air permeability of the glass cloth exceeds 5 cm ³ / (cm ² · s), the thermal expansibility increases and the adhesiveness of the copper foil also decreases. As is clear from the results of Comparative Example 2, when the proportion of particles having a particle size of 1 μm or less in the filler exceeds 40% by mass, the adhesiveness of the copper foil is lowered.

  Hereinafter, although embodiment was described, these embodiment was shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention.

  DESCRIPTION OF SYMBOLS 10 ... Prepreg manufacturing apparatus, 11, 12 ... Metal roll, 13, 14 ... Glass cloth, 15 ... Thermosetting resin composition, 16 ... Prepreg, 17, 18 ... Glass cloth layer, 19 ... Resin composition layer, 21, 22 ... Copper foil, 23 ... Substrate, 21 ... High filling layer, 22, 23 ... Resin layer.

Claims (6)

Producing a prepreg having a resin composition layer made of a thermosetting resin composition and a pair of glass cloth layers including a glass cloth and sandwiching the resin composition layer;
A step of bringing a copper foil into contact with both main surfaces of the prepreg and pressurizing in a reduced pressure atmosphere;
Have
The thermosetting resin composition used for the production of the prepreg contains 70 to 92% by mass of a filler, and the proportion of particles having a particle size of 1 μm or less in the filler is 40% by mass or less. A method for producing a low thermal expansion substrate, wherein the glass cloth used in the method has a thickness of 80 to 150 μm and air permeability of 5 cm ³ / (cm ² · s) or less.   The method for producing a low thermal expansion substrate according to claim 1, wherein the resin composition layer has a thickness of 300 to 1200 μm, a softening point of 50 to 120 ° C., and a melt viscosity at 100 ° C. of 200 Pa · s or less. .   3. The low thermal expansion according to claim 1, wherein the glass cloth used for producing the prepreg is a plain weave glass cloth, and the average diameter of the filaments constituting the glass cloth is 5 to 13 μm. Of manufacturing a conductive substrate.   The method for producing a low thermal expansion substrate according to any one of claims 1 to 3, wherein the thermosetting resin composition contains a thermosetting resin, a curing agent, and a curing accelerator.   5. The thermosetting resin includes at least one epoxy resin selected from a crystalline epoxy resin, a biphenyl type epoxy resin, and an epoxy resin solid at normal temperature having a softening point of 120 ° C. or less. The manufacturing method of the low thermal expansion board | substrate of description.   The method for manufacturing a low thermal expansion substrate according to any one of claims 1 to 5, wherein the filler includes an inorganic filler.

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