JPH11107187A - Nonwoven fabric for highly thermoconductive laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject nonwoven fabric, high in thermal conductivity, excellent in electroinsulating characteristics, thin, low in void fraction, high in density and light by including, as the major ingredients, a heat-resistant high-molecular-weight material, a binder and a specific content of a highly thermoconductive material. SOLUTION: This nonwoven fabric is a sheet made of a highly thermoconductive material (e.g. aluminum nitride), a heat-resistant high- molecular-weight material and a binder, which is compressed in the thickness direction into a printed-wiring board (for producing highly multi-layered circuits). The highly thermoconductive material is included in the nonwoven fabric at 10 wt.% or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

2. Description of the Related Art CPUs, LEDs, power modules and the like are considered as heat-generating components in an electric circuit on a printed wiring board. If these components cause an excessive rise in local temperature, the life of the components will be shortened, leading to a decrease in the reliability of the device. As a countermeasure against this, conventionally, aluminum radiating fins are installed, air is blown by a small fan, and a power circuit is cut off from a control circuit to design.

However, as electronic components have become smaller and more sophisticated,
As high-speed circuits, high-density wiring, and high-density packaging are progressing, heat dissipation of electric circuits is becoming more important than ever. Among the fastest computers equipped with CPUs with high-speed arithmetic processing, which have been increasing in recent years, the highest-speed computers may overheat the chip to around 100 ° C. Crowded and very dangerous. Therefore, a printed wiring board on which a large number of heat-generating components of small size and high performance are mounted cannot obtain a stable operating environment without heat radiation design.

[0003] In addition to notebook computers,
Recent electronic products are also becoming smaller and lighter in packaging. Instead of using many radiating fins, the printed wiring board itself has been required to have high heat radiation characteristics. There is also a movement to integrally design a power system and a control system in order to improve the space utilization rate of an on-board circuit.

[0004] At present, several printed wiring boards characterized by heat radiation characteristics have been developed and marketed to meet these requirements. The main one is a metal base or metal core printed wiring board in which an insulating layer is provided on the surface of a metal plate as a heat sink and a circuit is formed thereon. As the metal, aluminum that is inexpensive and has excellent thermal conductivity is often used. There is also a resin film for a substrate or a laminated board in which a heat conductive filler is mixed into a resin of an insulating layer so that heat of the resin layer is easily conducted to a metal base.

[0005] These improved products can actually cope with high heat dissipation and high-density wiring. However, currently, the insulating layer of the heat dissipation board on the market is mainly made of glass epoxy or polyimide, and the insulating layer in which the heat conductive filler is mixed into the resin is still small, so even if it is used in a circuit consisting of several layers, Often not used for layers.

However, as described above, at present, applications requiring high thermal conductivity in high multilayer circuits tend to increase.
When making a high-density wiring board by increasing the number of layers, the thickness of the board increases as the number of layers increases. Is increased. Therefore, in order to efficiently release the heat generated on the substrate surface, it is necessary to improve the thermal conductivity of both the base material and the resin.

As a remarkable technique relating to this,
The following patents have been proposed. JP-A-60-136298 discloses that by using a prepreg in which a base material is impregnated with a resin containing a heat conductive substance as an adhesive prepreg, excellent heat conductivity or heat dissipation and high density of a wiring board are provided. A method for facilitating multi-layering and multi-layering is described. Japanese Patent Application Laid-Open No. 63-102927 discloses a heat sink and other materials having excellent heat conductivity in which one or more metal layers and a polymer matrix composite material layer based on a heat conductive material such as fibers or whiskers are laminated. There is a description of a laminated plate useful as a heat dissipating plate. Japanese Patent Application Laid-Open No. 63-132045 discloses that a nonwoven fabric sheeted with kraft fiber containing at least 90% of alumina fiber is used as a part or all of the base material, thereby providing a laminate excellent in both heat radiation characteristics and through hole reliability. There is a board. JP-A-6-162855 discloses that epoxy resins, polyimide resins, resins alone such as polyphenylene oxide, and resins modified from these resins, resin varnishes composed of a combination of these resins, have excellent thermal conductivity such as alumina and aluminum nitride. Blended inorganic filler, impregnated into glass, inorganic fiber non-woven fabric such as ceramic fiber, dried,
It is said that it is semi-cured to obtain a sheet having high thermal conductivity.

Although these conventional techniques will have a great effect on improving the thermal conductivity of a printed wiring board, problems arise when the technique is adapted to a high multilayer circuit. In other words, when a high-layer circuit is manufactured using these conventional techniques and inventions, the thickness of the printed wiring board itself increases as the number of layers increases, so that regardless of whether a metal plate is used as a heat sink, Since the distance from the cooling surface increases, the time required for heat transfer increases, and cooling efficiency decreases.

When only the base material having improved thermal conductivity is used and the matrix resin, which is an ordinary resin which is not particularly improved in thermal conductivity, is used, the heat conductivity of the base material itself becomes important. It is becoming. That is, the heat conduction of the substrate greatly depends on the space factor of the heat conductive substance contained in the base material,
In addition, since the porosity of the substrate is greatly affected, the rate of addition of the thermally conductive substance and the density of the substrate itself are important. For this reason, when a high multilayer circuit is manufactured by a conventional technique or an invention, the resin content is inevitably increased due to the high porosity of the base material, and the thermal conductivity of the substrate is reduced.

[0010]

Therefore, the following items can be considered as conditions required for the nonwoven fabric for a laminate of the present invention. -Good heat conduction characteristics.・ Excellent insulation properties.・ Thin, low porosity, high density, preferably lightweight. An object of the present invention is to provide a nonwoven fabric for a laminate having the above conditions.

[0011]

Means for Solving the Problems The present inventors made a nonwoven fabric by forming a sheet of a high heat conductive substance and a heat resistant polymer material, and further subjected to a compression process in the thickness direction, and this nonwoven fabric was used as a substrate for a printed wiring board. As a result of examining the use as a material, the nonwoven fabric contains a heat conductive substance in a high volume composition ratio, and has a low porosity, high density, and thinness. And found that they had excellent thermal conductivity.

That is, a first invention of the present invention relates to a nonwoven fabric for a laminate mainly comprising a heat-resistant polymer material, a binder and a high thermal conductive material, wherein the high thermal conductive material is a nonwoven fabric.
The present invention relates to a nonwoven fabric for a laminate containing at least wt%. According to a second aspect of the present invention, there is provided a laminated structure according to the first aspect, wherein the thermal conductivity of the high thermal conductive substance is 10 W / mK (W is watt, m is meter, K is absolute temperature). The present invention relates to a nonwoven board. According to a third aspect of the present invention, the high thermal conductive substance according to the first or second aspect is such that aluminum nitride, beryllia, nickel aluminide, silicon carbide, alumina, graphite, boron, titanium diboride, boron nitride, boron nitride, The present invention relates to a nonwoven fabric for a laminate, which is at least one substance selected from aluminum diboride and molybdenum disilicide. The fourth invention of the present invention is the second invention or the third invention.
The highly heat-conductive substance in the invention of (1) relates to a nonwoven fabric for a laminate having any form of filler, whisker, fine fiber, and chopped strand.

According to a fifth aspect of the present invention, the heat-resistant polymer material of the first invention is a fluorine-based polymer material, a silicone-based polymer material, an aromatic heterocyclic polymer material, a thermosetting heat-resistant high material. The present invention relates to a nonwoven fabric for a laminate, which is at least one material selected from a molecular material, a thermoplastic heat-resistant polymer material, and the like. The sixth invention of the present invention relates to a nonwoven fabric for a laminate, wherein the heat-resistant polymer material according to the fifth invention has any form of fiber, chopped strand, pulp, or fine fiber. Still further, the seventh invention of the present invention is the non-woven fabric for a laminate, wherein the volume composition ratio of the high thermal conductive substance in the first to sixth inventions is 7 vol% or more of the nonwoven fabric for a laminate. 80% by volume or less.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A high thermal conductive substance used in the present invention is defined as having a lowest thermal conductivity of 10 W / mK or more when the thermal conductivity W / mK is measured in a measurement temperature range of 0 to 100 ° C. The substance refers to, for example, aluminum nitride, beryllia, nickel aluminide, silicon carbide, alumina, graphite, boron, titanium diboride, boron nitride, aluminum diboride, molybdenum disilicide, and the like. These high heat conductive substances are used alone or in combination of two or more. Fillers, whiskers,
There are fine fibers, chopped strands and the like. The filler has various shapes such as a granular shape, a spherical shape, a cylindrical shape, a flake and the like. The amount of high thermal conductive material is 10
It is not less than wt% and not more than 87 wt%. The lower limit of the amount is limited as described above, because if the amount is less than this, the volume composition ratio of the high heat conductive material cannot be sufficiently increased when the sheet is compressed in the thickness direction. If the ratio exceeds the upper limit, the strength is not preferable.

The heat-resistant polymer material used in the present invention is a fluorine-based polymer material, a silicone-based polymer material, an aromatic heterocyclic polymer material, a thermosetting heat-resistant polymer material, a thermoplastic heat-resistant polymer. Fibers, chopped strands, pulp, fine fibers, etc. selected from materials and mixtures thereof. Among these polymer materials, solder resistance temperature is 26
Materials that can maintain sufficient strength for a short time at 0 ° C. correspond to the heat-resistant polymer material of the present invention. Illustrative material names include aromatic polyamide, aromatic polyimide, polybenzimidazole, phenol, polyoxamidrazone, polyphenylene oxide, polyaminobismaleimide, polytetrafluoroethylene, polyphenylene sulfide, melamine, polyphenylene benzobisoxazole , Polyetheretherketone, polyarylate, polyethersulfone, ultrahigh molecular weight polyethylene, flame-resistant acrylic, and the like, and copolymers thereof.

A non-woven fabric is prepared by mixing a heat-resistant polymer material selected from the above and a highly heat-conductive substance, and adding a binder to the non-woven fabric. For example, a chopped strand is used as an aggregate to capture the highly heat-conductive substance. It may be made into a sheet by mixing pulp with the like. Also, if necessary, the highly heat-conductive substance should be aggregated and aggregated as a suitable floc, and if mixed with a heat-resistant polymer material, the highly heat-conductive substance should be contained in the nonwoven fabric very effectively. Is possible.

The nonwoven fabric for a laminate of the present invention is added with an organic binder represented by a phenolic, silicone, epoxy, acrylic or the like in order to impart strength to the nonwoven fabric. The shape of the binder is fiber, powder, emulsion,
An aqueous solution can be used, but any binder can be used by selecting an appropriate addition method. The addition method is a method of adding binder fibers or powder to the slurry of the raw material as an internal addition method, mixing and mixing, and an external addition method, a method of spraying an emulsion or an aqueous solution onto a papermaking wet paper as a spray, or a method of applying the papermaking wet paper to an emulsion or There are a method of impregnating with a binder solution composed of an aqueous solution, a method of coating a papermaking wet paper with a binder solution composed of an emulsion or an aqueous solution, and combinations thereof are also conceivable, and any of them may be used.

The nonwoven fabric of the present invention is subjected to compression processing in the thickness direction of the nonwoven fabric sheet so as to contain a high heat conductive substance in a high volume composition ratio. As a compression method, a calendar process is generally effective, but any other effective method may be used. The pressure depends on the type of fiber and binder used, but it is about 50-500 kg / cm when using a calendar. The compression does not necessarily need to be completed in one treatment, and the target volume composition ratio is 7 vol% or more (preferably 10 vol% or more) of the high thermal conductive substance and 80 vol% or less (preferably 70 vol%).
vol%).

It is effective to perform heating by a roll at the same time as necessary during the compression working. This helps deform the fiber using the thermoplastic properties, making it easier to work thinner.However, when using two or more types of fibers with different melting points or softening points, the temperature can be controlled by controlling the temperature. It is possible to increase the strength by using heat fusion of the fiber on the low temperature side.

[0020]

Next, the present invention will be described specifically with reference to the following examples.

Example 1 Copolyparaphenylene / 3,4'oxydiphenylene terephthalamide (para-aramid resin) chopped strand (manufactured by Teijin Limited, trade name: Technora) 20 wt%,
10% by weight of pulp of polyparaphenylene terephthalamide (para-aramid resin) (trade name: Twaron, manufactured by Akzo) and 60% by weight of aluminum nitride (thermal conductivity: 150 W / mK; manufactured by Toshiba Chemical) were mixed by a wet method. An acrylic latex binder (manufactured by Dainippon Ink) was sprayed onto the obtained wet paper at an effective solid content of 10 wt%, dried at 145 ° C., and the fibers were bonded to each other to obtain a nonwoven fabric for a laminate. Next, the nonwoven fabric was pressed at 120 ° C. and 100 kg / cm with a steel-steel calender. Table 1 shows the characteristic values of the nonwoven fabric after the compression treatment.

The compressed non-woven fabric is impregnated with epoxy resin varnish, dried and semi-cured at 150 ° C. to prepare a prepreg, and pressed at a surface pressure of 50 kgf / cm ² and 165 ° C. for 60 minutes to form a 2-ply laminate. Created. The thermal conductivity of the nonwoven fabric and the laminate after the compression processing was measured by a Kemtherm QTM-D3 thermal conductivity meter manufactured by Kyoto Electronics Industry Co., Ltd., and shown in Table 2.

Example 2 50% by weight of chopped strand (manufactured by Teijin Limited, trade name: Technora) of copolyparaphenylene / 3,4'oxydiphenylene terephthalamide (para-aramid resin),
10% by weight of polyparaphenylene terephthalamide (para-aramid resin) pulp (trade name: Twaron, manufactured by Akzo) and 30% by weight of aluminum nitride (thermal conductivity: 150 W / mK; manufactured by Toshiba Chemical) were mixed by a wet method. An acrylic latex binder (manufactured by Dainippon Ink) was sprayed onto the obtained wet paper at an effective solid content of 10 wt%, dried at 145 ° C., and the fibers were bonded to each other to obtain a nonwoven fabric for a laminate. Next, this nonwoven fabric was compressed at 120 ° C. and 100 kg / cm using a steel-steel calender. Table 1 shows the characteristic values of the nonwoven fabric after the compression treatment.

The compressed nonwoven fabric is impregnated with epoxy resin varnish, dried and semi-cured at 150 ° C. to prepare a prepreg, and is pressed at a surface pressure of 50 kgf / cm ² and 165 ° C. for 60 minutes to form a 2-ply laminate. Created. The thermal conductivity of the nonwoven fabric and the laminate after the compression processing was measured by a Kemtherm QTM-D3 thermal conductivity meter manufactured by Kyoto Electronics Industry Co., Ltd., and shown in Table 2.

Example 3 Polyparaphenylene 2,6-benzobisoxazole chopped strand (manufactured by Toyobo Co., Ltd., trade name: PBO) 20w
t%, chopped strand of polymetaphenylene isophthalamide (manufactured by Teijin Limited, trade name: Conex) 10
wt% and chopped strands of alumina (thermal conductivity: 20 W / mK; manufactured by Nichibi Co., Ltd.) were mixed by a wet method. The obtained wet paper was impregnated with an epoxy latex binder (manufactured by Dainippon Ink) to adjust the effective solid content to 10% by weight, and then dried at 145 ° C. to bond the fibers together to obtain a nonwoven fabric for a laminate. Next, the nonwoven fabric was compressed at 120 ° C. and 50 kg / cm using a steel-steel calender. Table 1 shows the characteristic values of the nonwoven fabric after the compression treatment.

The non-woven fabric after the compression treatment is impregnated with epoxy resin varnish, dried and semi-cured at 150 ° C. to prepare a prepreg, and pressed at a surface pressure of 50 kgf / cm ² and 165 ° C. for 60 minutes to form a 2-ply laminate. Created. The thermal conductivity of the nonwoven fabric and the laminate after the compression processing was measured by a Kemtherm QTM-D3 thermal conductivity meter manufactured by Kyoto Electronics Industry Co., Ltd., and shown in Table 2.

Example 4 Copolyparaphenylene / 3,4'oxydiphenylene terephthalamide (para-aramid resin) chopped strand (manufactured by Teijin Limited, trade name: Technora) 20 wt%,
10% by weight of pulp of polyparaphenylene terephthalamide (para-aramid resin) (trade name: Twaron, manufactured by Akzo) and 60% by weight of aluminum nitride (thermal conductivity: 150 W / mK; manufactured by Toshiba Chemical) were mixed by a wet method. An acrylic latex binder (manufactured by Dainippon Ink) was sprayed onto the obtained wet paper at an effective solid content of 10 wt%, dried at 145 ° C., and the fibers were bonded to each other to obtain a nonwoven fabric for a laminate. Table 1 shows the characteristic values of this nonwoven fabric.

This non-woven fabric is impregnated with an epoxy resin varnish, and dried and semi-cured at 150 ° C. to prepare a prepreg.
It was pressed at 0 kgf / cm ² and 165 ° C. for 60 minutes to prepare a 2-ply laminate. Table 2 shows the thermal conductivity of nonwoven fabric and laminates measured with a Kemtherm QTM-D3 thermal conductivity meter manufactured by Kyoto Electronics Industry Co., Ltd.
It was shown to.

Comparative Example 1 70% by weight of chopped strand of copolyparaphenylene / 3,4'oxydiphenylene terephthalamide (para-aramid resin) (trade name Technora, manufactured by Teijin Limited)
20% by weight of pulp (trade name: Twaron, manufactured by Akzo) of polyparaphenylene terephthalamide (para-aramid resin) was mixed by a wet method. An acrylic latex binder (manufactured by Dainippon Ink) is added to the obtained wet paper at an effective solid content of 10 wt%.
And dried at 145 ° C. to bond the fibers together to obtain a nonwoven fabric for a laminate. Next, the nonwoven fabric was pressed at 120 ° C. and 100 kg / cm with a steel-steel calender.
Table 1 shows the characteristic values of the nonwoven fabric after the compression treatment.

The non-woven fabric after the compression treatment is impregnated with epoxy resin varnish, dried and semi-cured at 150 ° C. to prepare a prepreg, and pressed at a surface pressure of 50 kgf / cm ² and 165 ° C. for 60 minutes to form a 2-ply laminate. Created. The thermal conductivity of the nonwoven fabric and the laminate after the compression processing was measured by a Kemtherm QTM-D3 thermal conductivity meter manufactured by Kyoto Electronics Industry Co., Ltd., and shown in Table 2.

Comparative Example 2 Chopped strand of copolyparaphenylene / 3,4'oxydiphenylene terephthalamide (para-aramid resin) (trade name: Technora), 20 wt%,
10% by weight of pulp of polyparaphenylene terephthalamide (para-aramid resin) (manufactured by Akzo, trade name: Twaron) and glass powder (thermal conductivity: 0.89 W / mK; manufactured by Nippon Glass Fiber Co., Ltd., trade name: Microglass Milled) Fiber) 60wt
% Was mixed as a nonwoven fabric by a wet method. An acrylic latex binder (manufactured by Dainippon Ink) was sprayed onto the obtained wet paper at an effective solid content of 10 wt%, dried at 145 ° C., and the fibers were bonded to each other to obtain a nonwoven fabric for a laminate. Next, this non-woven fabric is put on a steel-steel calender at 120 ° C and 100 kg / cm.
Compression processing. Table 1 shows the characteristic values of the nonwoven fabric after the compression treatment.

The compressed nonwoven fabric is impregnated with epoxy resin varnish, dried and semi-cured at 150 ° C. to prepare a prepreg, and pressed at a surface pressure of 50 kgf / cm ² and 165 ° C. for 60 minutes to form a 2-ply laminate. Created. The thermal conductivity of the nonwoven fabric and the laminate after the compression processing was measured by a Kemtherm QTM-D3 thermal conductivity meter manufactured by Kyoto Electronics Industry Co., Ltd., and shown in Table 2.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

The nonwoven fabric for laminates of the present invention improves the thermal conductivity of the nonwoven fabric to about 1.2 to 1.8 kcal / mh ° C. when, for example, 60 wt% of a high heat conductive substance is blended. this is,
Thermal conductivity of ordinary non-woven fabric for laminated board is 0.3 ~ 0.5 kcal / mh ℃
This is very high as compared with before and after, and it is clear that the effect of the present invention is remarkably exhibited. This effect is also maintained when a laminate is used.

Since the nonwoven fabric for a laminate of the present invention is subjected to compression processing using organic fibers as main fibers, the thickness becomes about 1/2 to 1/3 in comparison with the same rice tsubo. Therefore, the sheet is very thin, has a high density, is advantageous for rapid heat conduction, and has characteristics as a sheet for a high multilayer laminate.

The nonwoven fabric for a laminated board of the present invention can obtain good heat conductivity and reduce the weight even if a printed wiring board without a heat sink is formed only by a base material and a resin having improved heat conductivity. . Alternatively, even when a glass cloth is used as the core material, the heat radiation effect is enhanced when used in combination with a high thermal conductive base material. Of course, the combined use with the heat sink further enhances the heat radiation effect.

Claims (7)

[Claims] 1. A non-woven fabric for a laminate comprising a heat-resistant polymer material, a binder and a high thermal conductive material as main components, wherein the high thermal conductive material contains 10% by weight or more of the non-woven fabric. 2. The nonwoven fabric for laminated boards according to claim 1, wherein the high thermal conductive substance is a substance having a thermal conductivity of 10 W / mK or more. 3. The high thermal conductivity material is aluminum nitride,
The material according to claim 1 or 2, wherein the material is at least one substance selected from beryllia, nickel aluminide, silicon carbide, alumina, graphite, boron, titanium diboride, boron nitride, aluminum borohydride, and molybdenum disilicide. Non-woven fabric for laminates. 4. The nonwoven fabric for a laminate according to claim 2, wherein the high thermal conductive substance has any form of a filler, a whisker, a fine fiber, and a chopped strand. 5. The heat-resistant polymer material includes fluorine-based polymer materials, silicone-based polymer materials, aromatic heterocyclic polymer materials, thermosetting heat-resistant polymer materials, and thermoplastic heat-resistant polymer materials. The nonwoven fabric for a laminate according to claim 1, wherein the nonwoven fabric is at least one selected material. 6. The nonwoven fabric for a laminate according to claim 5, wherein the heat-resistant polymer material has any form of fiber, chopped strand, pulp, or fine fiber. 7. The nonwoven fabric for a laminate according to any one of claims 1 to 6, wherein the volume composition ratio of the high thermal conductive substance is 7 vol% or more of the nonwoven fabric for a laminate, and the volume composition ratio of the void is 80 vol% or less of the nonwoven fabric for a laminate. The nonwoven fabric for a laminate according to the above.