SE531018C2 - Use of a composite material as thermal contact material for microelectronic components - Google Patents

Description

531 018 2 Today's materials for capacitors have become the limiting factor for miniaturization of electronics. As examples of small capacitors such as "01005 size", 0.2 x 0.2 x 0.4 mm, are only available in small capacitance ranges. There is therefore a great need for materials that can increase the capacitance of capacitors and dare to promote miniaturization of electronic equipment. 531 GiB Summary of the invention The aim of this invention is to present a material that has significantly higher thermal conductivity and better mechanical properties than materials available today. This material will be important in thermal regulation of microelectronics today and in the future and to increase the reliability of electronics.

The invention today is related to good thermally conductive nanostructures consisting of polymeric nanobres with mixed thermally conductive nanoparticles (silicon carbide, SiC, boron nitride (BN), silver particles (Ag)), microparticles (copper, (Cu)), carbon nanotubes (Carbon NanoTs) or CNbon NanoTs other particles. The thermal conductivity of the nanostructure of varying thickness is significantly improved in the presence of other thermally conductive particles, either by particle encapsulation in nanometers or by attaching nanoparticles to the surface of nanoparticles during the electrospinning process.

These nanostructure thin materials are attractive as a thermally conductive material in microelectronics due to their properties such as high elasticity, purity, high thermal conductivity and its ability to be formed into thin layers. These properties meet the challenge of continued miniaturization of microelectronics.

Another objective of the invention is to create new high capacitance materials consisting of polymeric nanobres mixed with inorganic nanoparticles (eg BaTiO 3) for capacitors. These thin materials can be used to reduce the size of the capacitors that allow continued miniaturization of electronics.

Yet another object of the invention is to create a simple and inexpensive method for producing thin composite materials consisting of nanobres and other metallic, inorganic or organic particles in the nano- or micro-scale.

BRIEF DESCRIPTION OF DRAWINGS, FIGURES OCI-1 TABLES Figure 1 is a schematic illustration of the electrospinning technique.

Figures 2a and 2b are photographs with scanning electron microscopy of nanoparticles of phenolic resin (2a) with silver nanoparticles (2b).

Figure 3 shows a typical application of the material as thermal contact material.

Figure 4 shows a typical application of the material as a capacitor.

Table 1 shows typical thermal and mechanical properties of some different nanofiber materials compared to conventional materials from 3M. 53% D18 DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION.

Figure 1 shows the electroplating technique, which is used to produce nanofibers mixed with nanoparticles, microparticles and / or nanotubes. In the process, a polymer (preferably a resin with high elasticity, strong cohesion, impact resistance, toughness and extensibility, for example polyurethane and phenolic resins) is dissolved in an organic solvent (for example mixture of tetrahydrofuran, THF, and dimethylformamide, DMF, advantageously by 40-60% by weight THF). For thermal contact materials, nano- or microparticles with high thermal conductivity (eg silicon carbide (SiC), bomitride (BN), silver (A9), copper (Cu) and gold (Au)), carbon nanotubes and / or other particles can be mixed with the viscoelastic polymer solution.

For applications where high capacitance is desired, inorganic nanoparticles can be mixed with the polymer solution. For adhesion, the components of the adhesive (harder and base) can be mixed directly into the polymer solution. To improve the homogeneity of the solution, for example, magnetic stirring can be used.

With the solution placed in a capillary (1) or syringe, an electrostatic field (high voltage, for example between 15-50 kV) is applied between the solution and the collector (3) (for example an aluminum foil). The collector is located at a certain distance from the capillary tube (1). When the electrostatic force (2) overcomes the surface tension of the cone or droplet (4) protruding from the end of the capillary tube (1), a jet of polymer solution (5) is created. By stretching the electrostatic field, the beam creates nano-fragile structures with electrostatic charge. These fragile structures travel through the air down to the collector and during the journey the solvent evaporates. This results in extremely thin fibers (usually less than 100 nm in diameter) accumulating on the collector (3). Nano fi brema has a large surface area (per unit mass) and relatively small pores. Different structures can be fabricated using this method, such as random distributed structures and directed structures.

If desired, the nanoparticles (7) can be encapsulated in the nanoseptic polymeric material or used to cover the surface of polymers and create tennis conductive structures.

Thin layers or foils of different thicknesses consisting of nano-brittle structures, advantageously mixed with nanoparticles, microparticles, carbon nanotubes and / or other 53% G13 particles can be manufactured. Thin layers (a few tens to one hundred micrometers in thickness) with nano-brittle polymer mixed with some of the above-mentioned particles have been made.

Especially for application as a thermal contact material, in a realization of the invention, 2% by weight of carbon nanotubes with a thermal conductivity of about 2,000 W / (Km) have been used (in a special case, walled carbon nanotubes, MWCNTs, 10 nm - 30 nm in diameter) were used. In another case, 5% by weight of SlC (beta) particles (45 nm - 55 nm in diameter) with a thermal conductivity of about 150 W / (Km) were used. In a further realization, 20% by weight of Ag particles (0.5 μm - 1 μm in diameter) with a thermal conductivity of about 420 W / (Km) were used. Cu (0.5-1.5μm) particles have also been used.

Nanoparticles and microparticles of gold, diamond, silicon nitrate, (SiN), boron nitrate (BN) with fl era can also be used.

With regard to the application of the invention as a thermal contact material, in a realization, silicone oil can advantageously be placed on the collector and / or the fibers in order to facilitate the removal of the nanobrema from the collector. If desired, the produced material can be further soaked in silicone oil. The use of silicone oil further increases the tin conductivity of the thermal contact material of this invention.

It is believed that the increased conductivity is due to the silicone oil filling the small cavities and pores between the fibers and around the particles by capillary force.

Table 1 shows typical thermal and mechanical properties of the slightly different manufactured nano-brittle materials as examples.

Binders (for example conductive adhesives) can, if desired, be included in the above-mentioned mixture to give the thin layers and foils produced adhesive properties and thus facilitate their use as thermal contact materials. Finally, in the realization of the invention, protective adhesive of polyester can be applied on top of the nano-bearing material (for example nano-adhesive tape or tape). The purpose of the protective strap is to protect the product during transport and handling. The protective strap is removed during use.

In particular with regard to the application area of the invention as a material with high capacitance, inorganic nanoparticles (eg BaTIOS) have been used. 531 018 Figure 2a shows a scanning electron microscopy photograph of a piece of material made of polyurethane-based nanoparticles with Ag nanoparticles. Figure 2b shows a photograph of a piece of material made of polyurethane-based nanometers and carbon nanotubes soaked in silicone oil.

Figure 3a shows a possible application of the thermal contact material in this invention.

In Figure 3a, material 2 is placed between the integrated circuit 1 and the heat sink 3.

The direction of heat dissipation is given by arrow 4. In Fig. 3b, the nanofiber material 2 is placed between the integrated circuit (IC) 1 and the substrate 3 to improve the heat dissipation in the so-called "die attach" application.

Figure 4 shows a possible application of the material of this invention for capacitors.

Material 2 is placed between two metal layers, the signal plane 1 and the ground plane 3.

It is to be understood that this invention may be practiced otherwise than as exemplified above without departing from the spirit of the present invention.

The invention is thus not limited to exactly the constructions and methods outlined above. Thus, the examples and realizations shown should in all respects be seen as illustrative, not restrictive, and the invention should not be construed as limited by the details presented. Those familiar with the subject matter of the invention will see further alternatives in terms of material selection and methods for realizing the invention in accordance with the claims set forth below. 53% CVIB 7 Table 1. Measurement data Properties Unit SM material 3M material Phenolic resin based Polyurethane based 5506 5509 nanofiber with nano fibers with CNT impregnated silver particles silicone oil Thermal W / (Km) 4.0-5.2 4.4-6.5 4.39 0.37 -0.93 Conductivity Layer thickness pm 1000 500 100 90 Thermal resistance K / W 0.91-1.17 0.36-0.55 0.11-0.30 0.46-1.17 Working temperature QC 50-130 50-130 70 to 90 50-120 Temperature for QC 500 500 400 410 decomposition Maximum MPa 0.09 0.22 0.55 4.48 stress at break (elongation speed: 8.10 ° / s) Maximum elongation% 54.1 29.5 15 455 at break (elongation speed: 8.10 “° / s) E-module MPa 0.31 0.76 3.67 1, O1 Color Gray Gray Black light gray

Claims (4)

531 018 New Claim Use of a composite material as a thermal contact material for heat transport for microelectrical components of varying thickness which include polymeric nanoubbers and nanoparticles, nanotubes, microparticles or a mixture thereof in the form of organic, inorganic, ceramic and / or metallic materials with high thermal conductivity . In the use according to claim 1, said polymer may be of polyurethane, polysulfones, polyimide, surface crystalline polymer (LCP) and / or other functional polymers or mixtures of these or other polymers with high thermal conductivity, elasticity, compositional strength, impact resistance, toughness and high ductility. In the use according to claim 1, said nanoparticles and inicroparticles may consist of gold (AU), silver (Ag), copper (Cu), lead-free and Sn-based nan solder, diamond, silicon carbide (SiC), silicon nitride (SiN), borninide ( BN), carbon nanotubes or CNT (one or fl wall) and all other subterranean conductive nanoparticles and microparticles and mixtures thereof. In the use of claim 1 wherein said nanoparticles, microparticles and CNT tubes are encapsulated or coated in said nanoparticles or mixtures of these situations.