CN100496186C - Bulk high thermal conductivity material and method of making thereof - Google Patents

Abstract

The invention relates to a feedstock material for use in making heat spreaders, comprising a sheet of annealed pyrolytic graphite having a thermal conductivity of greater than 1000 watts/m-K, a thickness of at least 0.2 mm, and a size in any other dimension of at least 5 cm. In one embodiment, the feedstock is made by hot-pressing a stack of alternate layers of pyrolytic graphite sheets with flat graphite dies for a finished sheet of annealed pyrolytic graphite comprising a plurality of layers being parallel to each other of at least 0.075 degrees per mm of thickness. In another embodiment, the finished sheet of annealed pyrolytic graphite is made by graphitizing a stack of films comprising a high-carbon polymer.

Description

Bulk high thermal conductivity feedstock and preparation method thereof

The cross reference of related application

Present patent application requires the priority of the U.S. Provisional Application patent 60/504537 of application on September 19th, 2003.

Invention field

The present invention relates to the heat of heat treatment pyrolytic graphite and the large volume sheet (bulksheet) of electrical conductivity compound, in one application as radiator (heat spreader), for example heat is spread from thermal source, the invention still further relates to the formation method of the large volume sheet of heat treatment pyrolytic graphite.

Background of invention

Electronics and/or integrated circuit (" IC ") instrument, for example microprocessor, memory etc. all become more and more littler, and be meanwhile but more and more higher to the requirement of heat radiation.For the heat that these instruments are produced dissipates, radiator and/or fin have been used.

Disclose different materials and design, be used to manage and remove heat from electronic instrument.U.S. Patent number 5,296,310 disclosed a kind of between a pair of dough sheet (face sheet) that comprises metal or matrix-enhancing metal, clip material of high thermal conductivity mix (hybrid) constructional device.Core material can be highly regular pyrolytic graphite, compression annealing pyrolytic graphite (CAPG), synthesizing diamond, the compound that uses these materials or materials similar.United States Patent (USP) 6,215,661 have been disclosed the radiator that comprises L shaped heat treatment pyrolytic graphite (the thermal pyrolytic graphite) sheet that is encapsulated in the aluminium.United States Patent (USP) 5,958,572 have proposed a kind of heat radiating material, and it comprises the plug-in part (insert) of heat treatment pyrolytic graphite (TPG), diamond-like carbon and similar material with a plurality of passages that are formed on wherein, so that by a plurality of channel transfer hot-fluid optimizations.

The pyrolytic graphite of forms more of the prior art, particularly those pyrolytic graphites that make by the chemical vapor deposition (CVD) process (TPG) are because crystal face thickness difference has problem in uneven thickness.Adjacent crystal layer is parallel basically, but is changing in the crystal scale accumulation (crystallographic scale accumulate) on the macroscopic thickness.For example, on 1 mm-scale, natural aspect air spots is capable.Have required thermal conductance the heat treatment pyrolytic graphite " watt " (thermalpyrolytic graphite " tile ") be used to prepare radiator in the prior art.But they have only relatively little size usually, and are wide as 2cm, 0.1cm is thick, can only be used for making relatively little radiator.United States Patent (USP) 6,407,902 provide solution about the radiator with small size pyrolytic graphite watt, and it comprises heat treatment pyrolytic graphite thin slice (theremal pyrolytic graphite flake) is incorporated in the host material.The composite graphite material can be processed into the radiator that needs size, does not re-use a plurality of fixing undersized graphite tile of the prior art.

Exist a kind of like this needs, the high thermal conductivity material that requirement provides quality and size to be improved, with the device that is used for electronics and IC instrument are dispelled the heat, promptly require to provide the material of the raw material (feedstock material) that are suitable for use as preparation radiator, fin etc.Equally also need to make the raw-material method of this high heat conductance.

Summary of the invention

In one aspect of the invention, the raw material that are used to make radiator have been disclosed, this raw material comprise that pyroconductivity is greater than 5cm, the thickness annealing pyrolytic graphite of 0.2mm (the annealed pyrolytic graphite) sheet at least at least of the size on 1000W/m-K, any dimension (dimension), comprising a plurality of graphite planes, each flatness that has (flatness) is less than every millimeter thickness of about 0.075 degree.

The present invention also further relates to the preparing raw material method, these raw material comprise that pyroconductivity is greater than 5cm, the thickness annealing pyrolytic graphite thin slice of 0.2mm at least at least of the size on 1000W/m-K, any dimension, comprising a plurality of graphite planes, each flatness that has is less than every millimeter thickness of about 0.075 degree.

The accompanying drawing summary

Fig. 1 is the perspective view of annealing pyrolytic graphite sheet, thickness T wherein, length of side L, deviation angle P.

Detailed Description Of The Invention

The applicant has developed a kind of raw material of novel preparation heat management/heat sink applications. In this article, radiator can with the Alternates such as fin, heat pipe, refer to the heat management device or the heat transfer apparatus that comprise for the material of high thermal conductivity of the heat radiation of IC circuit, electronic instrument etc. or heat extraction.

As known in the art, along with the increase of raw material thickness, the collimation of the TPG layer of large-scale production is destroyed. The thickness of TPG can be expressed as in distance L during greater than 25mm, and the deviation angle P of every thickness T is defined as follows and is also shown among Fig. 1:

$p=\frac{1}{T}{\tan }^{-1}\left(\frac{\mathrm{\δT}}{L}\right),$ Wherein δ T is the varied in thickness along the distance L direction.

Know also in this area that the feature of graphite is the layer structure of carbon atom, have two main shafts, one is " c " axle, it is generally acknowledged the axle or the direction that are perpendicular to carbon-coating; An axle in addition is " a " axle, is parallel to the direction of graphite linings, transverse to the c axle.

In one embodiment of the invention, novel raw material comprise that pyroconductivity is that 1000W/m-K, the size on any dimension are that 5cm (being length and width, girth etc.), thickness are the annealing pyrolytic graphite sheet of 0.2mm at least at least at least, and graphite plane or layer are parallel to each other and have and be expressed as the flatness of deviation angle P less than 0.075 every millimeter thickness of degree (on the c direction).In second embodiment of the present invention, deviation angle P is less than every millimeter thickness of 0.07 degree.In the 3rd embodiment, deviation angle P is less than every millimeter thickness of 0.05 degree.

The manufacturing of the raw material annealing pyrolyzing graphite material that conforms to quality requirementsPyrolytic graphite normally is prepared as follows: the gas (carbonaceous) with carbon containing under the low pressure passes through maintenance base material at high temperature, this moment occurs pyrolysis, and the pyrolytic graphite vapour deposition is on exposed wicking surface.

In one embodiment of the present invention, utilize the chemical vapor deposition (CVD) method, hydrocarbon gas such as methane, natural gas, acetylene etc. are led in about 1300-2500 ℃, the heating furnace of about 0.5-500 mmhg pressure.Hydrocarbon gas can have be fit to form as the surface of the base material of graphite (natural or synthetic) on carry out thermal decomposition, use flat base material, formation sheet or tabular pyrolytic graphite.

In the embodiment of a CVD method, with a spot of volatile alloying metal source (as BCl ₃, HfCl ₄, BF ₃Or the halide of other refractory metal) and hydrocarbon gas lead to together in the hot stove and go, can reduce stress level, be increased in the thickness of the TPG layer that deposits on the base material.In another embodiment, to reactant, thermal decomposition product and substrate all the diluent gas of inertia be added in the hydrocarbon feed source.Diluent gas is helium, neon, argon, krypton, xenon, radon, hydrogen, nitrogen etc. normally.The adding of diluent gas helps the speed of control carbon laydown, thus the gained thickness of control pyrolytic graphite sheet or plate.

After pyrolytic graphite sheet and base substrate peeled off, it is carried out thermal anneal process.But in the process of cool to room temperature, the thermal stress of introducing in the material makes that (bow, wrinkle) situation arrive the every 100mm leaf length of 1mm greatly to pyrolytic graphite sheet generation gauffer.

In annealing steps, pyrolytic graphite continues heating about 10-30 minute in the temperature more than 2900 ℃, and the time is formed highly oriented pyrolytic graphite (HOPG) thus or is sometimes referred to as heat treatment pyrolytic graphite (TPG) by the thickness and the volume decision of the product of annealing.In the method, crystalline form taking place change, make the orientation of layer plane make moderate progress, reduced the thickness (reducing) perpendicular to layer plane on the c direction, is increasing (increasing on a direction) on length and the Width.It is the final products of outstanding pyroconductivity of 1000W/m-K at least that the increase of improved orientation and crystal size has obtained.

The applicant finds in annealing process these layers are carried out " healing " that hot extrusion (hot-pressing) can be surprising or handled the gauffer situation, make it possible to prepare TPG raw material like this with required quality, for example large-sized TPG sheet with abundant pyroconductivity and graphite linings collimation can be applied in the heat management field.Hot extrusion process can be used method and apparatus as known in the art, for example uses mould (die), roll shaft preparations such as (roller).

In one embodiment of the invention, pyrolytic graphite is heat-treated in above-mentioned temperature range, and is carrying out hot extrusion on the mould to remove the enclosed mass or the gauffer of the injustice that produces on carbonaceous sheet or base material in chemical vapour deposition (CVD).Mould can be isotropic graphite cake, and size for example covers the surface area of at least 75% graphite flake corresponding to the full-scale or portion size of graphite flake.In a kind of specific embodiments of this treatment step, pyrolytic graphite sheet or sheet material (board) and alternately stack of flat graphite cake (plate), the weight of uppermost graphite briquetting (block) is added to weight on each graphite sheet equably.

In another embodiment of the invention, the carbon raw material uses with the form (rather than hydrocarbon gas) of high carbon polymer, is used for producing pyrolytic graphite sheet or sheet material.In an example of this process, the sheet of high carbon polymer (or film) is stacked together, and carries out hot pressing from the direction vertical with sheet under enough temperature, keeps one sufficiently long period, makes the polymeric material charing form graphite.In an example, one folded in one direction at least long, the thickness of 5mm (example comprises the Kapton of E.I.duPont de Nemours company less than 50 microns polyimide film

Upilex with Uniglobe-Kisco company

) be heated to about 2820-3000 ℃ and be used to carry out complete graphitization, forming annealing pyrolytic graphite sheet, graphite plane is parallel to each other, and flatness that promptly has or deviation angle are less than or equal to every millimeter thickness of about 0.075 degree.

In one embodiment of the invention and as European Patent Application No. is EP 432,944 A1 are told about, graphited pyrolytic graphite that makes or TPG handle with inserting agent (intercalating agent) subsequently, make graphited pyrolytic graphite peeling off or separating to become on the c axle be more prone to.After the insertion, promptly with after inserting the agent processing, this treated pyrolytic graphite can be rinsed or purify removes excessive slotting eight doses.

The example that inserts agent comprises organic or inorganic acid, as nitric acid, sulfuric acid, perhalogeno acid (perhalo acid) and their mixture; 7,7,8, the 8-four cyano to the dimethylene benzoquinones (tetracyanoquinomethane, TCNQ), TCNE (TCNE), 1,2,4,5-four cyano benzene (TCBN) etc.; Bromine and (three) iron chloride; The chlorate of nitric acid and potash.

The raw-material application of TPG of the present inventionIn an example of the present invention, finished product product by hot pressing/annealing in process is the TPG raw material (bulk TPG stock) of large volume, its pyroconductivity is 1000W/m-K at least, yardstick (not being thickness) on dimension is 5cm at least, the sheet that for example 5cm is wide, 10cm is long, 0.8cm is thick, comprise multilayer (being similar to shale and mica) graphite, seldom or do not have a fold (layer surperficial inhomogeneous), be parallel to each other between each layer, be defined as the flatness or the deviation angle that have and spend every millimeter thickness less than about 0.075.

In the above-mentioned example, the graphite linings of large volume TPG raw material can resolve into the layer with desired thickness subsequently, and thick 8 layers of 0.1cm for example are processed into independent watt, are used for Application Of Radiator.In an operation, the large volume TPG raw material of 5cm * 10cm of the present invention * 0.8cm can be processed into 64 square tiles that 2.4cm * 0.1cm is thick.

In example as a comparison, the raw material TPG sheet of prior art is used to make TPG watt of same size.The raw material of large volume is typical business-like, and the curvature of 0.1mm is arranged on 0.8cm is thick in the layer plane.This sheet is also peeled off as above-mentioned example, the thick tile of finished product of preparation 0.1cm.But, in order to obtain flat watt, the every side of the small pieces that each sheet is peeled off must have the excessive material of 0.1mm, to be used for processing, be that each stripping film must be that 1.2mm is thick, therefore have only the 6 thick planes of 0.1cm that connect layer can pass through the TPG feedstock production of prior art.This method minimum has 25% waste of material (6 parts with respect to using 8 parts of TPG raw material of the present invention), but also is lost in the course of processing to obtaining the needed time of the thick plain tile of 0.1mm.

Embodiment

Following embodiment is used for demonstrating the present invention, but is not limited to scope of the present invention.

In an embodiment, the TPG sheet makes by the CVD method, carry out thermal annealing in about 2900 ℃ of-3200 ℃ of temperature, arrived in lasting about 10 minutes up to 2 hours, wherein this sheet carries out hot pressing with isotropic graphite plate (isotropic graphite plates), simultaneously to the TPG sheet thermal annealing of the large volume of resulting the following example

Embodiment 1.In this embodiment, the deviation of thickness and thickness with the interval of every approximately 76mm along the TPG sheet along the 356mm linear measure longimetry.Deviation angle is by formula calculated.Find the P value less than every millimeter thickness of 0.075 degree, the result is as follows:

Apart from mm

L

25.4

101.6

177.8

254

356

Thickness difference mm	dT	0.05	0.127	0.228	0.279	0.355
							Thickness mm	T	15.21	15.26	15.26	15.29	15.39
Degree/mm thickness	P	0.007	0.005	0.005	0.004	0.004

Embodiment 2.In second embodiment, thickness and thickness deviation are measured once every 76mm on the long TPG sheet of 380mm.Deviation angle is calculated by formula.Find that the P value is also less than every millimeter thickness of 0.075 degree.

Apart from mm	L	25.4	101.6	177.6	254	356
							Thickness difference mm	dT	0.152	0.127	0.279	0.533	1.066
Thickness mm	T	10.71	10.74	10.76	10.81	11.02
							Degree/mm thickness	P	0.032	0.007	0.008	0.011	0.016

Embodiment 3.The skew of thickness and thickness is measured once every 76mm on the long TPG sheet of 260mm in the present embodiment.Deviation angle is calculated by formula.Find that the P value is equally also less than every millimeter thickness of 0.075 degree.

Apart from mm	L	25.4	101.6	177.6	254
						Thickness difference mm	dT	0.177	0.12	0.076	0.279
Thickness mm	T	13.46	13.58	13.66	13.7
						Degree/mm thickness	P	0.007	0.003	0.001	0.005

Though the invention describes preferred implementation, those of ordinary skills can various corrections can occur on the basis that does not break away from the scope of the invention, and parts are wherein worked as the thing replacement with waiting.Do not plan to limit the invention to the enforcement preferred plan of the present invention that disclosed, all specific implementations in the claim scope all are contained among the present invention.

All references quoting in the present invention all known and is incorporated into herein as a reference.

Claims (15)

1, a kind of annealing pyrolytic graphite raw material comprise annealing pyrolytic graphite sheet material, and the pyroconductivity that described graphite sheet has is greater than 1000W/m-K, and thickness is at least 0.2mm and at least one other dimension is at least 5cm,

Wherein said annealing pyrolytic graphite sheet material comprises the flat graphite flake of a plurality of that be parallel to each other and flatnesses less than every millimeter thickness of 0.075 degree.

2, annealing pyrolytic graphite raw material according to claim 1, length that has and width are 5cm separately at least.

3, according to each described annealing pyrolytic graphite raw material among the claim 1-2, the thickness that has is 0.5mm at least.

4, annealing pyrolytic graphite raw material according to claim 1 are forms of the graphitization sheet material of polyimides.

5, annealing pyrolytic graphite raw material according to claim 4, the graphitization sheet material of wherein said polyimides are included at least about graphited under 2800 ℃ the temperature, the thickness a plurality of polyimide films less than 50 microns.

6, annealing pyrolytic graphite raw material according to claim 1 are forms of the hot extrusion sheet material of pyrolytic graphite.

7, annealing pyrolytic graphite raw material according to claim 6, time wherein by a lamination and pyrolytic graphite sheet are heated the sufficient time section under enough temperature and pressures, hot extrusion sheet material to described pyrolytic graphite carries out hot pressing, so that the pyrolytic graphite in the described pyrolytic graphite sheet is changed into highly oriented pyrolytic graphite.

8, annealing pyrolytic graphite raw material according to claim 6, wherein said pyrolytic graphite sheet material is by a plurality of graphite cake hot pressing.

9, the raw-material method of a kind of manufacturing annealing pyrolytic graphite, this method comprises the following steps:

With one or multi-disc at least the dimension except that thickness be the pyrolytic graphite heating of 5cm at least,

With temperature heating and the extrusion of lip-deep described one or the multi-disc pyrolytic graphite that are stacked to one or more plate at least 2900 ℃;

Thereby form one or multi-disc annealing pyrolytic graphite, comprise that a plurality of that be parallel to each other, pyroconductivities are greater than 1000W/m-K, the thickness graphite plane of 5cm at least of the size on 0.2mm, any other dimension at least in every millimeter thickness of at least 0.075 degree.

10, method according to claim 9, wherein said one or more plates comprise graphite.

11, according to each described method among the claim 9-10, wherein said one or more plates are moulds.

12, a kind of formation is used for making the method for the heat treatment pyrolytic graphite watt of heat management instrument, and described method comprises:

The sheet material of annealing pyrolytic graphite is peeled off into the pyrolytic graphite of stratification, and the pyroconductivity of described sheet material is that size on 0.2mm, any other dimension is 5cm at least greater than 1000W/m-K, thickness at least;

The pyrolytic graphite of described stratification is machined for the heat management instrument enough dimensions watt;

The sheet material of wherein said annealing pyrolytic graphite comprises a plurality of graphite planes that are parallel to each other in every millimeter thickness range of at least 0.075 degree.

13, a kind of goods, it comprises heat treatment pyrolytic graphite that the method for claim 12 makes watt.

14, a kind of goods, it comprises the annealing pyrolytic graphite raw material that the method for claim 9 is made.

15, a kind of goods, it comprises among the claim 1-8 each annealing pyrolytic graphite raw material.

Images