CA2026452A1 - Composite material having good thermal conductivity - Google Patents
Composite material having good thermal conductivityInfo
- Publication number
- CA2026452A1 CA2026452A1 CA 2026452 CA2026452A CA2026452A1 CA 2026452 A1 CA2026452 A1 CA 2026452A1 CA 2026452 CA2026452 CA 2026452 CA 2026452 A CA2026452 A CA 2026452A CA 2026452 A1 CA2026452 A1 CA 2026452A1
- Authority
- CA
- Canada
- Prior art keywords
- composite material
- weight percent
- thermal conductivity
- filler
- waxes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/20—Oxides; Hydroxides
- C08K3/22—Oxides; Hydroxides of metals
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/28—Nitrogen-containing compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/34—Silicon-containing compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/38—Boron-containing compounds
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
- H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
- Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A highly heat-resistant composite material is used for electrically insulating and highly thermally-conductive parts in electrical and electronic components and comprises a highly heat-resistant polymer and an electrically-insulating, mineral filler having a high thermal conductivity. The composite material is filled, for example, with 50-90 weight percent sintered ceramic is injectable and extrudable and is well-suited for electrical components at 220 volts and operating temperatures up to 15°C. due to its high thermal conductivity above 1 W/mK, its dielectric strength of > 3 kV/mm and its high thermoforming stability of > 180°C.
A highly heat-resistant composite material is used for electrically insulating and highly thermally-conductive parts in electrical and electronic components and comprises a highly heat-resistant polymer and an electrically-insulating, mineral filler having a high thermal conductivity. The composite material is filled, for example, with 50-90 weight percent sintered ceramic is injectable and extrudable and is well-suited for electrical components at 220 volts and operating temperatures up to 15°C. due to its high thermal conductivity above 1 W/mK, its dielectric strength of > 3 kV/mm and its high thermoforming stability of > 180°C.
Description
- ` ~026~2 BACKGRQ~JND OF THE INVE~NTION
Fleld of the Inve t'on:
The present invention relates to a highly heat-resistant composite material as well as to the use thereof.
Desc~tion o~f the Prior Art The increasing mmiaturization of e]ectronic components and the increase in the packing density of electronic circuits and assemblies that accompanies the miniaturization creates problems due to the stray heat arising during operation of the components. Increasingly-greater quantities of heat is also to be dissipated from the components due to the higher power densi~y in order to protect the components against damage due to overheating.
Given closed envelopes or housings of components, the stray heat arising must be eliminated via the material of the envelope or, respectively, of the housing.
Known envelopes of unfilled thermoplastics, in fact, have good electrical insulation that is likewise required, but have a therrnal conductivity of approximately thnt is often inadequate.
In order to increase this low thermal conductivity, plastics filled with correspondingly thermally-conductive particles are now employed. ~e European patent 167 000 proposed aluminum particles as a filler. ~he filler particles are thereby covered with a closed polyethylene layer in order to guarantee an adequate electrical insulation of the plastic filled therewith. Therrnal conductivities of approximately _-5 W/mK are, in fact, achieved; however, an adequate dielectric strength in order to meet all requirements for utilization given components in 22Q volt operation is not 26~
achieved.
SUMMARY OF THE INYENllON
It is therefore an object of the preseilt invention to provide a material that has a good conductivi~y of at least 1.5 W/mK~ is thereby electrically insulating and has a puncture or breakdown voltage that allows utilization for components effectively operated with 220 volts.
The above object is achieved through a highly heat-resistant composite material composed of:
15 20 weight percent of a highly thermally-resistant thermoplastic polymer having a thermoforming stabllity greater than or equal to 180C.; and 50--85 weight percent of a mineral, crystalline filler baving a thermal conductivity greater than or equal J~K, whereby the extrudable and injectable composite material has a thermal conductivity of at least 1 W/mK, a thermoforming stability of greater than or equal to ~0~. and a dielectric strength of greater than or equal to 3 kV/mm.
According to a particular feature of the invention, the composite material is characterized in that it contains 2~-35 weight percent of the polymer.
According to another feature of the invention9 the composite material is particularly characterized in that the highly he~t-resistant polymer is a thermoplastic and is selected from the group consisting of liquid crystal polymers (LCP), `` 2~2~2 po]yphenylenesulfide ~PPS), polyetherirnide ~PEI), po]yethersulfone (PES)~
po]yetheretherketone (PEEK), polyethyleneterephthalate (PET), polysulfone (PSU), polyaryletherketone, polyarnide/irnide (PA~), polyimides (P~) and poly~mide (PA).
According to another feature of the invention, the eomposite material is characterized in that the filler is a sintered ceramic selected from the group consisting of alurninum nitride, aluminum oxide, boron nitride? silicon carbide, boron carbide and silicon nitride.
According to another feature of the invention, the composite material is characterized in that it is composed of ~ ~ weight percent of a liquid crystal polymer and 65--85 weight percent of a mineral filler having a thermal conductivity above 30 W/mK and an electrical volume resistance of greater than ~oz5 ohm cm.
According to another feature of the invention, the composite material mentioned immediately above is particularly characterized as having and at least sub-aromatic liquid crystal polymer that is selected from the group consisting of copolyester, polyester carbonate and polyester amide.
According to another feature of the invention, the composite material is characterized in that the filler has grain sizes smaller than ~m.
According to another feature of the invention, the composite material is particularly characterized in that the filler is present in tbe form of short fibers.
According to another feature of the invention, the composite material is particularly characterized in that it contains further, standard additives se]ected from an~i-statics, heat and light stabilizers, pigments, colorants, optical brightness, unmolding 2~2~
a~ iliaries, flame-retardant agents and gliding agents and lubricants, particularly fatty alcohols, dicarboxylic acid ester, fatty acid ester, fatty acids, ~atty acid soaps and fatty acid amides.
According to another feature of the invention, the compos~te rlaterial just mentioned is particularly characterized in that it contains 0!05--10 weight percent of one or more waxes which are selected from the group consisting of montanic acids (having 26--32 C atoms~, synthetic dicarboxylic acids having more than ~Q~ atoms, the esters and soaps thereo~, paraffin waxes, polyethylene waxes and polypropylene waxes and their oxidates, and amide waxes.
According to another feature of the invention, the composite material just mentioned is particularly characterized in that 0.1--5 weight percent waxes are contained therein.
According ~o another feature of the invention, the composite material is used for e]ectrica]]y insu]ating and highly thermally conductive parts in electric and electronic components, particularly as covering, envelope or housing of material.
BR~EF DESCR~PllON OF THE DRAWING
Other objects, features and advantages of the invention, its organization, construction and operation will be best understood from the following detailed description, taken in conjunction with the accompanying drawing, on which there is a single figure showing a cross sectional view of an electronic power component, such as for a motor vehicle, encapsulated for protection against environmental influences with a composite material manufactured in accordance with the present invention.
20~6~2 DESCRlPllON OF THE PREFERRED EMBODIMENTS
Referring to the drawing, an electronic power component (for example, for a motor vehicle) is illustrated that is encapsulated for protection against envirorLmental in~luences. A power transistor 4 is illustrated along with a somponent 3 of an assembly arranged on a printed circuitboard 2. The overall assembly ~2, 3, 4) is extrusion coated with the composite material of the present invention, so that the power component 1 is hermetically shielded from environmental influences, for example moisture, by the encapsulation 7. The electrical contact to the power supply can be produced via a plug-type connector 5.
~ he crux of the present invention is based on the advantageous and likewise surprising properties of the composite material manufactured in accordance with the invention. Mineral and hard fillers could previously be processed on]y with great difficulty since the hardness of the filler particles employed resulted in an increased abrasion of the apparatus employed and therefore made the processing uneconomical. Furthermore, a processing was heretofore possible only up to certain filler contents. Surprisingly, the composite material of the present invention exhibits a good extrudability and can be injected up to a maximum filler content of 85 weight percent. The thermal conductivities achieved in the recited range lie above 1.5 W/mK, whereby a dielectric strength of 3 kVefflmrn and above is simultaneously achieved This makes the composite material excellently suited for manufacturing envelopes, housing, etc, of electrical and electronic components wherein a high heat elirnination and simultaneously good electrical insulation are required.
The high filler contents and the properties of the composite material therefore achieved become possible on the basis of the selection of the polymer employed. The required temperature stability and thermoforming stability is met, for -`" 2~2~2 examp]e, by what is referred to as high^temperature thermoplastics that sirnultaneous]y have other bene~icial properties and are excel]ently suited to the composite materia].
These polymers have highly-ordered structures and thus create adequate space for filler partic]es up to the mentioned high percentage of fillers. These po]ymers thereby exhibit a high flowability under the processing conditions, particularly at high pressures and high processing temperatures, so that no sign~ficantly-higher forces must be exerted for processing the composite material, despite the high content of filler. The premature wear of the processing equ;pment and, thus, a shortening of their service life are ~hereby simultaneously prevented.
Highly heat-resistant thermoplastics that are also suitable for the composite material of the present invention are, in particular, liquid crystal polyrners (LCP~, polyphenylenesulfide (PES), polyetherimide (PE~), polyethersulfone (PES), polyetheretherketone (PEEK), polyethyleneterephthalate (PET), polybutyleneterephthalale (PBT), polysulfone (PSU~, polyaryletherketone, po]yamide/imide (PAI), polyimides (Pl) and various polyamides (for example, PA 46, PA 11 and PA 12).
Liquid crystal polymers whose very name testifies to their highly-or~ered structure, even in the fluid condition, are particularly suitable for the composite material of the present invention.
The highest degrees of filler are achieved with these polymers. Preferred liquid crSstal polymers have at least sub-aromatic structures and are selected from copolyester, polyester carbonate and polyester amide.
Fillers that likewise have a high thermal conductivity and are thereby electrically insulating are required îor a composite rnaterial having good thermal -` . 202~2 conductivity. These are particularly crystalline fillers wherein the thermal conduction arises due to lattice osc;llations (phonons) but not due to an electron contribution The electrically-insulating properties of the filler and, therefore, of the composite material are thereby guaranteed It is not, howevert thç conductivity of the filler that is predominantly decisive for a high thermal conductivity of the composite material; rather, it is the volume portion of the filler in the composite material. The selection criterion for a good filler is therefore the compatibility thereof with the thermoplastic or, respectively, its capability of achieving a high degree of filler in combination with a suitable thermoplastic.
Suitable fillers are selected from the group consisting of oxides, nitrides, and carbides of elements of the third through sixteenth main group. Such components belonging to the group of sintered cerarnics are, for example, aluminum nitride, aluminum oxide, boron nitride, silicon carbide, boron carbide and silicon nitride.
Aluminum nitride is a filler with which especially good properties of the cormposi~e material can be achieved. As a consequence of its high costs, however, the utilization thereof on an industrial scale is not economical. Aluminum oxide is to be preferred from this point of view. Silicon carbide represents a good compromise with respect to economical feasibility and properties. A composite material filled therewith, however, has a somewhat lower dielectric strength since silicon carbide is a weak semieondllctor.
The filler particles advantageously have green sizes below SO L~m. The shape of the particles is thereby arbitrary and ls only dependent on the manufacturing method. Although a composite material that has extraordinarily-good thermal conductivity properties is obtained given the use of short fibers as the filler, the fibers have heretofore not been economically useable because of their high costs. Filler - ` 2 ~ 2 contents of, for example, 5() volume percent are achieved given a filler having approximately spherical particles, this, for example, corresponding to 70 weight percent depelldent on the ~iller and on the polymer. Thermal conductiv~ties of approximately 2 WlmK are thus achieved.
Given the recited thermoplastics and the recited fillers, composite materials are obtained within the mentioned ranges that can already be well processed in this form, i.e. are extmdable and injectable, and that are well-suited for the electrical or, respectively, electronic applications. However, further constituent materials can be contained in the composite material for special purposes. These can be additives which are standard for achieving defined properties and which, for example, are selected from antistatics, heat and light stabilizers, pigments, colorants, optical brighteners, unmoldin~
auxiliaries, ilame-retarding additives or glide agents and lubricants. As already mentioned, no additives are required for the composite materials. In particular, composite materials having LCP as the thermop]astic meet the requirements for the flame retardant c]ass UL94 VO and are also particularly easy to process. Nonetheless, further advantages, particularly an easier workability~ can be achieved by adding, in particular, gliding agents and lubricants. Advantageous additives are therefore fatty alcohols, dicarboxylicacidester, fatty acid ester, fatty acids, fatty acid soaps and fatty acid amines or compounds derlved therefrom. For example, one or more waxes in a proportion of Q.05--10 weight percent can be contained in a composite material, particularly in a proportion of O.I--S weight percent. Such waxes, for example, are selected from montanic acids that have approximately 26--~2 C atoms, synthetic dicarboxylic acid having more than 20 C. atoms, their esters and soaps, parafine-polyethylene wax and polypropylene waxes and their oxidates, as well as amide waxes.
The composite materials are to be worked like standard thermoplastics.
They are extrudable and injectable. A suitable apparatus for processing the component ` 2026~2 materials is disc]osed, for example, in the European patent application 199 340. For producing the composite material, the corresponding thermoplastic ;s extruded a~ a granu]ate together with the filler. The material obtained in such a fashion can be converted into a granulate again and can be processed in this form into corresponding component parts in injection molding systerns. In industrial-scale systems, it is also possible to work the filler into the polymers by kneading.
Three compositions for cornposite material according to the teachings of the present invention will be set forth below as exemplary embodiments, the illustration thereof being illustrated on the drawing.
Examp]e # I
A m~xture that is composed of 70 weight percent aluminum oxide (granu]ation 0--3() lLm and 30 weight percent of a liquid crystal polymer (for example, Vectra C 950, Hoechst/Celanese) is extruded in a double worm extruded as disclosed, for example, in the European patent application 199 340.
Standardized injection molded parts for calculating the elec~rical and physical parameters are manufactured from this extruded mixture. The composite material has a thermal conductivity of 2 W/mK~ a specific volume resistance of above 1012 ohm cm, a puncture volta~e of more than ~e~ and a continuous use temperature of more than 150C. The flame-retardant specifications of UL 94 YQ are met up to a thickness of 2 mm.
The composite material can bç employed for eliminating stray heat in housings, or envelopes, or can be employed as a cooling member.
2~2~2 Examp]e ~2 Corresponding to the first example and first exemplary embodiment, a rr~xture of 60 weight percent silicon carbide (for example, Silcar N, Elektroschmelzwerk Kernpten) and 40 weight percene I CP (for example, Vectra C 950) are extruded.
T~njection-molded parts manufactured therefrom have a thermal conductivity of 1.5 W/mK, a specific volume resistance of more than 10l2 ohm cm, a puncture voltage of 3kVeff/mm and a continuous use temperature of at least one 150C. The flame-retardant specification of UL 94 VO are met up to 2mm.
Example ~3 Correspondlngly, a mixture of 35 weight percent aluminurn nitride (ESK
Company) and 65 weight percent LCP are extruded. ~ Injection-molded parts manufactured therefrom have a puncture voltage of more than 5 kV~,f~, a specific volume resistance of more than 10l2 ohm cm and a continuous use temperature of at least 150C. The flame-retardant specifications of UL 94 VO are likewise rnet up to 2 mm.
In a schematic cross-sectional view, the drawing illustrates an envelope for an electronic component manufactured from the composite material of the present invention.
Although we h~ve described our invention by reference to particular illustrative embodiments thereof, many changes and modifications of the imention may become apparent to those shlled in the~ art without departing from the spirit and scope of the invention. We therefore intend to include within the patent warranted hereon all such changes and modifications as may reasonably and properly be included within the scope of our contribution to the art.
Fleld of the Inve t'on:
The present invention relates to a highly heat-resistant composite material as well as to the use thereof.
Desc~tion o~f the Prior Art The increasing mmiaturization of e]ectronic components and the increase in the packing density of electronic circuits and assemblies that accompanies the miniaturization creates problems due to the stray heat arising during operation of the components. Increasingly-greater quantities of heat is also to be dissipated from the components due to the higher power densi~y in order to protect the components against damage due to overheating.
Given closed envelopes or housings of components, the stray heat arising must be eliminated via the material of the envelope or, respectively, of the housing.
Known envelopes of unfilled thermoplastics, in fact, have good electrical insulation that is likewise required, but have a therrnal conductivity of approximately thnt is often inadequate.
In order to increase this low thermal conductivity, plastics filled with correspondingly thermally-conductive particles are now employed. ~e European patent 167 000 proposed aluminum particles as a filler. ~he filler particles are thereby covered with a closed polyethylene layer in order to guarantee an adequate electrical insulation of the plastic filled therewith. Therrnal conductivities of approximately _-5 W/mK are, in fact, achieved; however, an adequate dielectric strength in order to meet all requirements for utilization given components in 22Q volt operation is not 26~
achieved.
SUMMARY OF THE INYENllON
It is therefore an object of the preseilt invention to provide a material that has a good conductivi~y of at least 1.5 W/mK~ is thereby electrically insulating and has a puncture or breakdown voltage that allows utilization for components effectively operated with 220 volts.
The above object is achieved through a highly heat-resistant composite material composed of:
15 20 weight percent of a highly thermally-resistant thermoplastic polymer having a thermoforming stabllity greater than or equal to 180C.; and 50--85 weight percent of a mineral, crystalline filler baving a thermal conductivity greater than or equal J~K, whereby the extrudable and injectable composite material has a thermal conductivity of at least 1 W/mK, a thermoforming stability of greater than or equal to ~0~. and a dielectric strength of greater than or equal to 3 kV/mm.
According to a particular feature of the invention, the composite material is characterized in that it contains 2~-35 weight percent of the polymer.
According to another feature of the invention9 the composite material is particularly characterized in that the highly he~t-resistant polymer is a thermoplastic and is selected from the group consisting of liquid crystal polymers (LCP), `` 2~2~2 po]yphenylenesulfide ~PPS), polyetherirnide ~PEI), po]yethersulfone (PES)~
po]yetheretherketone (PEEK), polyethyleneterephthalate (PET), polysulfone (PSU), polyaryletherketone, polyarnide/irnide (PA~), polyimides (P~) and poly~mide (PA).
According to another feature of the invention, the eomposite material is characterized in that the filler is a sintered ceramic selected from the group consisting of alurninum nitride, aluminum oxide, boron nitride? silicon carbide, boron carbide and silicon nitride.
According to another feature of the invention, the composite material is characterized in that it is composed of ~ ~ weight percent of a liquid crystal polymer and 65--85 weight percent of a mineral filler having a thermal conductivity above 30 W/mK and an electrical volume resistance of greater than ~oz5 ohm cm.
According to another feature of the invention, the composite material mentioned immediately above is particularly characterized as having and at least sub-aromatic liquid crystal polymer that is selected from the group consisting of copolyester, polyester carbonate and polyester amide.
According to another feature of the invention, the composite material is characterized in that the filler has grain sizes smaller than ~m.
According to another feature of the invention, the composite material is particularly characterized in that the filler is present in tbe form of short fibers.
According to another feature of the invention, the composite material is particularly characterized in that it contains further, standard additives se]ected from an~i-statics, heat and light stabilizers, pigments, colorants, optical brightness, unmolding 2~2~
a~ iliaries, flame-retardant agents and gliding agents and lubricants, particularly fatty alcohols, dicarboxylic acid ester, fatty acid ester, fatty acids, ~atty acid soaps and fatty acid amides.
According to another feature of the invention, the compos~te rlaterial just mentioned is particularly characterized in that it contains 0!05--10 weight percent of one or more waxes which are selected from the group consisting of montanic acids (having 26--32 C atoms~, synthetic dicarboxylic acids having more than ~Q~ atoms, the esters and soaps thereo~, paraffin waxes, polyethylene waxes and polypropylene waxes and their oxidates, and amide waxes.
According to another feature of the invention, the composite material just mentioned is particularly characterized in that 0.1--5 weight percent waxes are contained therein.
According ~o another feature of the invention, the composite material is used for e]ectrica]]y insu]ating and highly thermally conductive parts in electric and electronic components, particularly as covering, envelope or housing of material.
BR~EF DESCR~PllON OF THE DRAWING
Other objects, features and advantages of the invention, its organization, construction and operation will be best understood from the following detailed description, taken in conjunction with the accompanying drawing, on which there is a single figure showing a cross sectional view of an electronic power component, such as for a motor vehicle, encapsulated for protection against environmental influences with a composite material manufactured in accordance with the present invention.
20~6~2 DESCRlPllON OF THE PREFERRED EMBODIMENTS
Referring to the drawing, an electronic power component (for example, for a motor vehicle) is illustrated that is encapsulated for protection against envirorLmental in~luences. A power transistor 4 is illustrated along with a somponent 3 of an assembly arranged on a printed circuitboard 2. The overall assembly ~2, 3, 4) is extrusion coated with the composite material of the present invention, so that the power component 1 is hermetically shielded from environmental influences, for example moisture, by the encapsulation 7. The electrical contact to the power supply can be produced via a plug-type connector 5.
~ he crux of the present invention is based on the advantageous and likewise surprising properties of the composite material manufactured in accordance with the invention. Mineral and hard fillers could previously be processed on]y with great difficulty since the hardness of the filler particles employed resulted in an increased abrasion of the apparatus employed and therefore made the processing uneconomical. Furthermore, a processing was heretofore possible only up to certain filler contents. Surprisingly, the composite material of the present invention exhibits a good extrudability and can be injected up to a maximum filler content of 85 weight percent. The thermal conductivities achieved in the recited range lie above 1.5 W/mK, whereby a dielectric strength of 3 kVefflmrn and above is simultaneously achieved This makes the composite material excellently suited for manufacturing envelopes, housing, etc, of electrical and electronic components wherein a high heat elirnination and simultaneously good electrical insulation are required.
The high filler contents and the properties of the composite material therefore achieved become possible on the basis of the selection of the polymer employed. The required temperature stability and thermoforming stability is met, for -`" 2~2~2 examp]e, by what is referred to as high^temperature thermoplastics that sirnultaneous]y have other bene~icial properties and are excel]ently suited to the composite materia].
These polymers have highly-ordered structures and thus create adequate space for filler partic]es up to the mentioned high percentage of fillers. These po]ymers thereby exhibit a high flowability under the processing conditions, particularly at high pressures and high processing temperatures, so that no sign~ficantly-higher forces must be exerted for processing the composite material, despite the high content of filler. The premature wear of the processing equ;pment and, thus, a shortening of their service life are ~hereby simultaneously prevented.
Highly heat-resistant thermoplastics that are also suitable for the composite material of the present invention are, in particular, liquid crystal polyrners (LCP~, polyphenylenesulfide (PES), polyetherimide (PE~), polyethersulfone (PES), polyetheretherketone (PEEK), polyethyleneterephthalate (PET), polybutyleneterephthalale (PBT), polysulfone (PSU~, polyaryletherketone, po]yamide/imide (PAI), polyimides (Pl) and various polyamides (for example, PA 46, PA 11 and PA 12).
Liquid crystal polymers whose very name testifies to their highly-or~ered structure, even in the fluid condition, are particularly suitable for the composite material of the present invention.
The highest degrees of filler are achieved with these polymers. Preferred liquid crSstal polymers have at least sub-aromatic structures and are selected from copolyester, polyester carbonate and polyester amide.
Fillers that likewise have a high thermal conductivity and are thereby electrically insulating are required îor a composite rnaterial having good thermal -` . 202~2 conductivity. These are particularly crystalline fillers wherein the thermal conduction arises due to lattice osc;llations (phonons) but not due to an electron contribution The electrically-insulating properties of the filler and, therefore, of the composite material are thereby guaranteed It is not, howevert thç conductivity of the filler that is predominantly decisive for a high thermal conductivity of the composite material; rather, it is the volume portion of the filler in the composite material. The selection criterion for a good filler is therefore the compatibility thereof with the thermoplastic or, respectively, its capability of achieving a high degree of filler in combination with a suitable thermoplastic.
Suitable fillers are selected from the group consisting of oxides, nitrides, and carbides of elements of the third through sixteenth main group. Such components belonging to the group of sintered cerarnics are, for example, aluminum nitride, aluminum oxide, boron nitride, silicon carbide, boron carbide and silicon nitride.
Aluminum nitride is a filler with which especially good properties of the cormposi~e material can be achieved. As a consequence of its high costs, however, the utilization thereof on an industrial scale is not economical. Aluminum oxide is to be preferred from this point of view. Silicon carbide represents a good compromise with respect to economical feasibility and properties. A composite material filled therewith, however, has a somewhat lower dielectric strength since silicon carbide is a weak semieondllctor.
The filler particles advantageously have green sizes below SO L~m. The shape of the particles is thereby arbitrary and ls only dependent on the manufacturing method. Although a composite material that has extraordinarily-good thermal conductivity properties is obtained given the use of short fibers as the filler, the fibers have heretofore not been economically useable because of their high costs. Filler - ` 2 ~ 2 contents of, for example, 5() volume percent are achieved given a filler having approximately spherical particles, this, for example, corresponding to 70 weight percent depelldent on the ~iller and on the polymer. Thermal conductiv~ties of approximately 2 WlmK are thus achieved.
Given the recited thermoplastics and the recited fillers, composite materials are obtained within the mentioned ranges that can already be well processed in this form, i.e. are extmdable and injectable, and that are well-suited for the electrical or, respectively, electronic applications. However, further constituent materials can be contained in the composite material for special purposes. These can be additives which are standard for achieving defined properties and which, for example, are selected from antistatics, heat and light stabilizers, pigments, colorants, optical brighteners, unmoldin~
auxiliaries, ilame-retarding additives or glide agents and lubricants. As already mentioned, no additives are required for the composite materials. In particular, composite materials having LCP as the thermop]astic meet the requirements for the flame retardant c]ass UL94 VO and are also particularly easy to process. Nonetheless, further advantages, particularly an easier workability~ can be achieved by adding, in particular, gliding agents and lubricants. Advantageous additives are therefore fatty alcohols, dicarboxylicacidester, fatty acid ester, fatty acids, fatty acid soaps and fatty acid amines or compounds derlved therefrom. For example, one or more waxes in a proportion of Q.05--10 weight percent can be contained in a composite material, particularly in a proportion of O.I--S weight percent. Such waxes, for example, are selected from montanic acids that have approximately 26--~2 C atoms, synthetic dicarboxylic acid having more than 20 C. atoms, their esters and soaps, parafine-polyethylene wax and polypropylene waxes and their oxidates, as well as amide waxes.
The composite materials are to be worked like standard thermoplastics.
They are extrudable and injectable. A suitable apparatus for processing the component ` 2026~2 materials is disc]osed, for example, in the European patent application 199 340. For producing the composite material, the corresponding thermoplastic ;s extruded a~ a granu]ate together with the filler. The material obtained in such a fashion can be converted into a granulate again and can be processed in this form into corresponding component parts in injection molding systerns. In industrial-scale systems, it is also possible to work the filler into the polymers by kneading.
Three compositions for cornposite material according to the teachings of the present invention will be set forth below as exemplary embodiments, the illustration thereof being illustrated on the drawing.
Examp]e # I
A m~xture that is composed of 70 weight percent aluminum oxide (granu]ation 0--3() lLm and 30 weight percent of a liquid crystal polymer (for example, Vectra C 950, Hoechst/Celanese) is extruded in a double worm extruded as disclosed, for example, in the European patent application 199 340.
Standardized injection molded parts for calculating the elec~rical and physical parameters are manufactured from this extruded mixture. The composite material has a thermal conductivity of 2 W/mK~ a specific volume resistance of above 1012 ohm cm, a puncture volta~e of more than ~e~ and a continuous use temperature of more than 150C. The flame-retardant specifications of UL 94 YQ are met up to a thickness of 2 mm.
The composite material can bç employed for eliminating stray heat in housings, or envelopes, or can be employed as a cooling member.
2~2~2 Examp]e ~2 Corresponding to the first example and first exemplary embodiment, a rr~xture of 60 weight percent silicon carbide (for example, Silcar N, Elektroschmelzwerk Kernpten) and 40 weight percene I CP (for example, Vectra C 950) are extruded.
T~njection-molded parts manufactured therefrom have a thermal conductivity of 1.5 W/mK, a specific volume resistance of more than 10l2 ohm cm, a puncture voltage of 3kVeff/mm and a continuous use temperature of at least one 150C. The flame-retardant specification of UL 94 VO are met up to 2mm.
Example ~3 Correspondlngly, a mixture of 35 weight percent aluminurn nitride (ESK
Company) and 65 weight percent LCP are extruded. ~ Injection-molded parts manufactured therefrom have a puncture voltage of more than 5 kV~,f~, a specific volume resistance of more than 10l2 ohm cm and a continuous use temperature of at least 150C. The flame-retardant specifications of UL 94 VO are likewise rnet up to 2 mm.
In a schematic cross-sectional view, the drawing illustrates an envelope for an electronic component manufactured from the composite material of the present invention.
Although we h~ve described our invention by reference to particular illustrative embodiments thereof, many changes and modifications of the imention may become apparent to those shlled in the~ art without departing from the spirit and scope of the invention. We therefore intend to include within the patent warranted hereon all such changes and modifications as may reasonably and properly be included within the scope of our contribution to the art.
Claims (16)
1. A high-heat resistant extrudable and injectable composite material comprising:
15---20 weight percent of a highly heat-resistant thermoplastic polymer having a thermoforming stability of > 180°C; and 50---80 weight percent of a mineral crystalline filler having a thermal conductivity of > 10 W/mK, whereby the material has a thermal conductivity of at least 1 W/mK, a thermoforming stability of > 180°C. and a dielectric strength > 3 kV/mm.
15---20 weight percent of a highly heat-resistant thermoplastic polymer having a thermoforming stability of > 180°C; and 50---80 weight percent of a mineral crystalline filler having a thermal conductivity of > 10 W/mK, whereby the material has a thermal conductivity of at least 1 W/mK, a thermoforming stability of > 180°C. and a dielectric strength > 3 kV/mm.
2. The composite material of claim 1, wherein said heat-resistant polymer is further defined as comprising:
a thermoplastic material selected from the group consisting of liquid-crystal polymers, polyphenylenesulfide, polyetherimide, polyethersulfone, polyetheretherketone, polyethyleneterephthalate, polysulfone, polyaryletherketone, polyamide/imide, polyimides and polyamides.
a thermoplastic material selected from the group consisting of liquid-crystal polymers, polyphenylenesulfide, polyetherimide, polyethersulfone, polyetheretherketone, polyethyleneterephthalate, polysulfone, polyaryletherketone, polyamide/imide, polyimides and polyamides.
3. The composite material of claim 2, wherein said filler comprises a sintered ceramic selected from the group consisting of aluminum nitride, aluminum oxide, boron nitride, silicon carbide, boron carbide and silicon nitride.
4. The composite material of claim 1, wherein:
said filler comprises grain sizes smaller than 50 µm.
said filler comprises grain sizes smaller than 50 µm.
5. The composite material of claim 1, wherein:
said filler comprises short fibers.
said filler comprises short fibers.
6. The composite material of claim 1, and further comprising:
additives selected from the group head and light stabilizers, pigments, colorants, optical brighteners, unmolding auxiliaries, flame-retarding agents, and gliding agents and lubricants.
additives selected from the group head and light stabilizers, pigments, colorants, optical brighteners, unmolding auxiliaries, flame-retarding agents, and gliding agents and lubricants.
7. The composite material of claim 1, and further comprising:
additives selected from the group consisting of fatty alcohols, dicarboxylic acid ester, fatty acid ester, fatty acids, fatty acid soaps and fatty acid amides.
additives selected from the group consisting of fatty alcohols, dicarboxylic acid ester, fatty acid ester, fatty acids, fatty acid soaps and fatty acid amides.
8. The composite material of claim 6, and further comprising:
0.05---10 weight percent of at least one wax selected from the group consisting of montanic acids having 26---32 C atoms, synthetic dicarboxylic acids having more than 20 C atoms, the esters and soaps thereof, paraffin waxes, polyethylene waxes and polypropylene waxes and their oxidates, and amide waxes.
0.05---10 weight percent of at least one wax selected from the group consisting of montanic acids having 26---32 C atoms, synthetic dicarboxylic acids having more than 20 C atoms, the esters and soaps thereof, paraffin waxes, polyethylene waxes and polypropylene waxes and their oxidates, and amide waxes.
9. The composite material of claim 7, and further comprising:
0.05---10 weight percent of at least one wax selected from the group consisting of montanic acids having 26---32 C atoms, synthetic dicarboxylic acids having more than 20 C atoms, the esters and soaps thereof, paraffin waxes, polyethylene waxes and polypropylene waxes and their oxidates, and amide waxes.
0.05---10 weight percent of at least one wax selected from the group consisting of montanic acids having 26---32 C atoms, synthetic dicarboxylic acids having more than 20 C atoms, the esters and soaps thereof, paraffin waxes, polyethylene waxes and polypropylene waxes and their oxidates, and amide waxes.
10. The composite material of claim 8, wherein:
said wax is in the range of 0.1---5 weight percent.
said wax is in the range of 0.1---5 weight percent.
11. The composite material of claim 9, wherein:
said wax is in the range of 0.1---5 weight percent.
said wax is in the range of 0.1---5 weight percent.
12. A highly-heat resistant extrudable and injectable composite material comprising:
20---35 weight percent of a highly heat-resistant thermoplastic polymer having a thermoforming stability of > 180° C; and 50---80 weight percent of a mineral crystalline filler having a thermal conductivity of > 10 W/mK, whereby the composite material has a thermal conductivity of at least 1 W/mK, a thermoforming stability of > 180° C. and a dielectric strength of >
3kV/mm.
20---35 weight percent of a highly heat-resistant thermoplastic polymer having a thermoforming stability of > 180° C; and 50---80 weight percent of a mineral crystalline filler having a thermal conductivity of > 10 W/mK, whereby the composite material has a thermal conductivity of at least 1 W/mK, a thermoforming stability of > 180° C. and a dielectric strength of >
3kV/mm.
13. A highly-heat resistant extrudable and injectable composite material comprising:
20---35 weight percent of a highly heat-resistant thermoplastic polymer having a thermoforming stability of > 180°C; and 65---85 weight percent of a mineral crystalline filler having a thermal conductivity of > 30 W/mK, whereby the composite material has a thermal conductivity of at least 30 W/mK, and an electrical volume resistance of > 1015 ohm cm.
20---35 weight percent of a highly heat-resistant thermoplastic polymer having a thermoforming stability of > 180°C; and 65---85 weight percent of a mineral crystalline filler having a thermal conductivity of > 30 W/mK, whereby the composite material has a thermal conductivity of at least 30 W/mK, and an electrical volume resistance of > 1015 ohm cm.
14. A high heat-resistant extrudable and injectable composite material comprising:
15---35 weight percent of a highly heat-resistant thermoplastic polymer having a thermoformal stability of > 180°C; and 50---85 weight percent of mineral crystalline filler having a thermal conductivity of > 10 W/mK, whereby the material has a thermal conductivity of at least 1 W/mK, a thermoforming stability of > 180°C. and a dielectric strength of > 3 kV/mm.
16
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19893932882 DE3932882A1 (en) | 1989-10-02 | 1989-10-02 | WELL HEAT-CONDUCTING COMPOSITE |
| DEP3932882.1 | 1989-10-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2026452A1 true CA2026452A1 (en) | 1991-04-03 |
Family
ID=6390691
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2026452 Abandoned CA2026452A1 (en) | 1989-10-02 | 1990-09-28 | Composite material having good thermal conductivity |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0421193A1 (en) |
| JP (1) | JPH03126765A (en) |
| CA (1) | CA2026452A1 (en) |
| DE (1) | DE3932882A1 (en) |
| IE (1) | IE903510A1 (en) |
| PT (1) | PT95472A (en) |
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| CN103738022A (en) * | 2014-01-16 | 2014-04-23 | 柯瑞林 | Heat-conducting insulating composite material and preparation method thereof |
| US10377861B2 (en) | 2014-12-31 | 2019-08-13 | Sabic Global Technologies B.V. | Polyetherimide compositions, articles made therefrom, and method of manufacture thereof |
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| TW345667B (en) | 1996-09-09 | 1998-11-21 | Tokiin Corp | High thermal conductivity composite magnetic substance |
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| IT1314160B1 (en) * | 1998-09-30 | 2002-12-04 | Tessa Trading Ltd | METHOD AND APPARATUS FOR THE EXTRUSION OF HIGH INERT PERCENTAGES OF POLYMERS. |
| FR2784261B1 (en) * | 1998-10-05 | 2001-07-27 | Ge Medical Syst Sa | INCREASED ELECTRICAL INSULATION AND COOLING MATERIAL FOR THERMAL CONDUCTIVITY AND APPLICATION TO THE INSULATION OF A HIGH VOLTAGE SUPPLY DEVICE |
| JP4627105B2 (en) * | 2000-07-11 | 2011-02-09 | 電気化学工業株式会社 | High thermal conductive composition and its use |
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| MY136063A (en) | 2001-06-01 | 2008-08-29 | Furukawa Electric Co Ltd | Multilayer insulated wire and transformer using the same |
| DE10320464B4 (en) * | 2003-05-08 | 2008-04-30 | Forschungszentrum Karlsruhe Gmbh | Use of a molding compound for the production of sintered molded parts |
| JP4990148B2 (en) * | 2004-10-04 | 2012-08-01 | ソルヴェイ アドバンスド ポリマーズ リミテッド ライアビリティ カンパニー | Aromatic high glass transition temperature sulfone polymer composition |
| CN101522770B (en) * | 2006-10-12 | 2012-05-23 | 巴斯夫欧洲公司 | Thermally conductive polyester molding materials |
| JP2008214398A (en) * | 2007-02-28 | 2008-09-18 | Nippon Polypenco Ltd | Thermoconductive monomer-cast nylon-molded article |
| TW200900435A (en) | 2007-03-29 | 2009-01-01 | Fujifilm Corp | Organic-inorganic composite composition and fabrication method thereof, molded article and fabrication method thereof and optical component |
| JP2012156434A (en) * | 2011-01-28 | 2012-08-16 | Sumitomo Chemical Co Ltd | Power device and package for power device |
| US8741998B2 (en) | 2011-02-25 | 2014-06-03 | Sabic Innovative Plastics Ip B.V. | Thermally conductive and electrically insulative polymer compositions containing a thermally insulative filler and uses thereof |
| US8552101B2 (en) | 2011-02-25 | 2013-10-08 | Sabic Innovative Plastics Ip B.V. | Thermally conductive and electrically insulative polymer compositions containing a low thermally conductive filler and uses thereof |
| JP5713807B2 (en) * | 2011-06-09 | 2015-05-07 | 三菱エンジニアリングプラスチックス株式会社 | Thermoplastic resin composition and molded body |
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- 1989-10-02 DE DE19893932882 patent/DE3932882A1/en not_active Withdrawn
-
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- 1990-09-19 EP EP90118048A patent/EP0421193A1/en not_active Withdrawn
- 1990-09-28 CA CA 2026452 patent/CA2026452A1/en not_active Abandoned
- 1990-10-01 IE IE351090A patent/IE903510A1/en unknown
- 1990-10-01 JP JP26369490A patent/JPH03126765A/en active Pending
- 1990-10-01 PT PT9547290A patent/PT95472A/en not_active Application Discontinuation
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103738022A (en) * | 2014-01-16 | 2014-04-23 | 柯瑞林 | Heat-conducting insulating composite material and preparation method thereof |
| CN103738022B (en) * | 2014-01-16 | 2015-08-05 | 柯瑞林 | A kind of heat conductive insulating composite and preparation method thereof |
| US10377861B2 (en) | 2014-12-31 | 2019-08-13 | Sabic Global Technologies B.V. | Polyetherimide compositions, articles made therefrom, and method of manufacture thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03126765A (en) | 1991-05-29 |
| DE3932882A1 (en) | 1991-04-11 |
| PT95472A (en) | 1991-06-25 |
| IE903510A1 (en) | 1991-04-10 |
| EP0421193A1 (en) | 1991-04-10 |
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