GB2508320A

GB2508320A - Polymer thermal interface material

Info

Publication number: GB2508320A
Application number: GB1403631.3A
Authority: GB
Inventors: Yi Li; Ed Prack
Original assignee: Intel Corp
Current assignee: Intel Corp
Priority date: 2009-12-09
Filing date: 2009-12-09
Publication date: 2014-05-28
Anticipated expiration: 2029-12-09
Also published as: GB2508320B; GB201403631D0

Abstract

A thermal interface material (TIM) comprises a polymer matrix which may be carbon fibre material, a flexible epoxy, a thermoplastic or a phase change material; a matrix additive comprising a fluxing agent or an antioxidant; and a spherical filler material comprising a metallic core with an organometallic polymer solderability preservative coating.

Description

POLYMER THERMAL INTERFACE MATERIAlS

BACK GROUND OF THE INVENTION

Polymer compourds have been used as a thcrraal inteJa mater al TIM to bud, for example, an integrated circuit the with an integrated heat spreader (JHSi However.

the process of curing and reliability stress on the TIM can lead ía problems of delarninaiion arid reduc.ed thermal conductivity.

BRIEF DESflflQEn.DPAW1NGS SVhiIO thc specilication concludes with claims particularly poindig ou and distinctly claiming that winch is regrdcd as the pnent invernion, the advarnages of this tnverdio.1 can be more readily ascertained from the following description of the mvcniion when read ixi conjuncion with flu accompanying drawings in wh!ch: FIG. I represents apd)mer thermal interface material according to an embodIment of the present invenaon.

FRI 2 represents a cross-section of a spherical filler material according to an embodiment of the present inven.ior,.

PIG. 3 reprtsents application of a polymer thermal interfitce material according to an embodiment of the present invention

DETATLED DESCPJPTJON OF THE PRESENT INVENTION

In the following detailed dewription, refrEence is made to the accornpaiying dmv ing.; that show, by way of fflustnttion, sptific embodiments in which the invention may be practiced These embodiments arc de3cribed in sufficient detail to enable those skilled in the art to practice the inve'ttion. It is to be understood that the vaflous etukodimenis of the iavcatioui, although different, aae not necessarily mutually exclusive.

For example, a particular feature. stncture, or characteristic der.cribed herein, in comiectEen with one embodiment, may be implemented withm other emL'adimenls without deparnn from tltciffi anrcope of the mventron. In addition, it is to be understood that the kication or arrdngcment of mdividual elements within each dLcciocd embodiment may be!m;'difed without departing fron'j the.pirit and scope of the iruention. The following detailed description is, therefore, not to be taken in a bmuing sense, and the cecipe of the present invention jq defined only by the appended claims, appropriately inteipreted. along wzth the 6iiI rangc of cquivaknts to which the cktms arc entitled. In the drannga. like numerats refbr ía the same or similar functionalily throughoal the several views.

FIG. 1 represents a polymer thermal interface material according to an embodiment of the present invention. As shown, lIM 100 contains polymer matrix 102, matrix additive 104, spherical filler material 106 and fibrous material l0, though the present invention is not so limited. In one embodiment, TIM 100 may not include all materials shown in Fig. 1, for example, without fibrous material lOS, or may include other materials not shown.

Polymer matrix 102 may provide TIM 100 with adhesion and flexibility properties.

In one embodiment, polymer matrix 102 is a silicone-based gel. In another embodiment, polymer matrix 102 is a flexible epoxy which combines the benefits of higher adhesion of I 0 epoxy and better flexibility of silicones. One example of a flexible epoxy is aliphatic polyglycol di-epoxide. In another embodiment, polymer matrix 102 is a thermoplastic such as acetal, acrylic, cellulose, acetate, polyethylene, polystyrene, vinyl, nylon or combinations thereof In another embodiment, polymer matrix 102 is a phase change polymer such as polyofefin. polyesters, silicones, paraffins or acrylics.

1 5 Matrix additivc 104 may be present to enhance the interface properties between polymer matrix 102 and spherical filler material 106 and/or allow better thermal conduction. In one embodiment, matrix additive 104 is a fluxing agent, for example short chain but low volatile carboxylie acids, amino acids, aldehyde, rosins, and polymeric acid with acid groups in backbone or in side chains. In another embodiment, matrix additive 104 is an antioxidant or thermal stabilizer to prevent the oxidation and degradation of polymer matrix 102 during heating and enhance thermal stability. Some examples of antioxidants or thermal stabilizers include Cyanox, benzoquinone, Cyasorb, 2,4,6-tri-tert-butylphenol, and Diphenylaminc.

Spherical filler material 106 is designed to provide TIM 100 with enhanced thermal conductivity and may have a makeup as shown in reference to Fig. 2. While shown as having honiogenous diameters, spherical filler material 106 may have varying diameters. In one embodiment, spherical filler material 106 varies in diameter from about to about 30 micrometers.

Fibrous material 108 may be added to TIM 100 to allow an expandable thermal path during TIM expansion. In one embodiment, fibrous material 108 is a carbon fiber with a high L/D (length/diameter) ratio. In one embodiment, fibrous material 108 has a concentration of up to about 8% by volume of TIM 100.

FIG. 2 represents a cross-section of a spherical filler material according to an embodiment of the present invention. As shown, spherical lifler nateáal 10 may include core 202, rnner 4hell 204 and outer sheH 206, however in ore emhodmients* spheneal tiller material 106 may not include all layers shown, for example, without timer shell 204, Or mu)' (IWIudc additional laycm nor shown.

S Core 202 mprcsents the bulk of spherical filler material 106. In one cmbc4imcnt, core 02 s a solder, metal, low-mefliug alloy, or other highly thermally conductive mareña. In another embodiment, core 202 is an expanding polymer material, such d3vmyl benzene crosslinked-po ncr, with a rela:ively bgh coefuient of thenmal expansion to provide gap tUling durin tItennal exçosurc thereby allowing effective thermal contact throughout the thermal exposure range. Inner shell 04 and(or ouer shell 206 nwy kO\ ide sph&ical filler material 106 with improved Thermal conductivity and/cu oxidation preentnn. in one embodiment, ;hera core 202 is an expan&ng polymer material, inner shell 204 is a conductive metal layer and outer shell 206 is a solder iu)'er In anc,thcr embodiment wherc core 202 is a themially conductive tint oxidative unstable material, such as ow-melting alloy (LMA), otcr shell 206 is an organic soiderability preservative (OSP) coating. In one embodiment, an OSP is composed of organomemihc polymer s a result of The eoordiuauon reaction between OSP active components, perbap r.olc or imidazole based, and the solder atoms at the surthce of core 202 br inner shell 204).

FIG. 3 represents an application of a polymer thermal mierface material according to an embodiment of the present invention. Shown is package structure 300. wherein the T[M 100 may be disposed bdven a We 302 and a heat bprcadcr structure 304, and a,so ma> be disposed between a heat prcader structure 304 and the heat sml structure $06 The TIM 100 may comprise any of 1e e-tbodiments of the pre3eot invention In one embodiment, the die 302 may comprise a silicon die, and the package strt.cture 300 may comprise a ccrar&c package and/or an organic package structure.

Although the foregoing description has specified certain step and materials that may be used in the method of the precen: irivenuon, those skilled in the art will appreciate that itany niodiikadonc and subatituions ma; be made. According, it i u.tended ihat all such modtlications, alterations. subtCtutions and additionr be considered to fall within thein4-tft4scnpe of the mt ention as defined by the appended claims. In adduton, it s appreciated that certain aspects of microelectronic dcvic are well known m the an.

Thedore, li is appreciated that the flgtres provided herein illustrate onl portions of an exemplary microelectronic structure that pertains to the practice of the present invention.

Ihus the present invention is not limited to the structures described herein.

Claims

Claims 1. A thermal interface material (TIM) comprising: a polymer matrix; S a matrix additive, wherein the matrix additive comprises a fluxing agent; and a spherical filler material, wherein the spherical filler material comprises a metallic core with an organometallic polymer solderability preservative coating.
2. The material of claim 1 further comprising carbon fiber material.
3. The material of claim 1 wherein the polymer matrix comprises a flexible epoxy.
4. The material of claim 1 wherein the polymer matrix comprises a thermoplastic.
5. The material of claim 1 wherein the polymer matrix comprises a phase change polymer.
6. The material of claim 1 further comprising wherein the TIM is disposed between a die and a heat sink structure.
7. A thermal interface material (TIM) comprising: a polymer matrix; a matrix additive, wherein the matrix additive comprises an antioxidant and a spherical filler material, wherein the spherical filler material comprises a metallic core with an organometallic polymer solderability preservative coating.
8. The material of claim 7 further comprising carbon fiber material.
9. The material of claim 7 wherein the polymer matrix comprises a flexible epoxy.
10. The material of claim 7 wherein the polymer matrix comprises a thermoplastic.
11. The material of claim 7 wherein the polymer matrix comprises a phase change polymer.
12. The material of claim 7 further comprising wherein the TIM is disposed between a die S and a heat sink structure.